403 forbidden<br> 403 forbidden<br> ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (2) 175-180 licensed under a creative commons *corresponding author. e-mail: kebelem@gmail.com attribution-noncommercial 4.0 international license. registration of ‘diga-2’ finger millet (eleusine coracana sub.spp. coracana) variety dagnachew lule2, kebede dessalegn1*, chemeda birhanu1, girma mengistu2, gudeta bedada1, megersa debela1, girma chemeda1, geleta gerema1, hailu feyisa1, megersa kebede1, and fufa anbessa1 1bako agricultural research centre, p.o. box 03, bako, ethiopia 2oromia agricultural research institute, p.o. box 81265, addis ababa, ethiopia abstract background: finger millet is an important staple food crop widely grown in ethiopia. the national average yield is far below the potential yield of the crop. limited availability of stable, high yielding and disease tolerant finger millet varieties is one of the major production constraints in the country. objective: the objective of this study was to identify stable high yielding and diseases tolerant genotypes for production. materials and methods: twelve black seeded pipeline finger millet genotypes were evaluated under a regional variety trial at bako and gute research stations from 2014 to 2016 main cropping seasons including the standard (degu) and local checks using randomized complete block design. diga-2 variety is black seeded finger millet (eleusine coracana sub.spp. coracana) with the pedigree of acc. bkfm0010 has been collected from beneshangul gumuz regional state by ethiopian institute of biodiversity. results: the results from additive main effect and multiplicative interaction (ammi) and eberhart and russell regression stability models as well as genotype and genotype by environment interaction (gge) biplot analysis revealed that diga-2 variety was relatively stable and high yielder (2.38 t ha-1) among the tested genotypes. the new variety, diga-2 had a yield advantage of 33.7% over degu, the standard check variety used for multi-environment evaluation. conclusion: among the tested genotypes, diga-2 finger millet variety was selected and released in 2018 for its high grain yield potential, stable and resistant against finger millet blast (magnaporthe oryzea) disease which is the most important finger millet production constraints in ethiopia in general and western oromia in particular. keywords: additive main effect and multiplicative interaction; blast (magnaporthe oryzea); genotype by environment interaction; stability 1. introduction finger millet (eleusine coracana (l.) gaertn) is an allotetraploid (2n = 4× = 36) annual cereal crop that includes two distinct sub-species: coracana (cultivated finger millet) and africana (wild finger millet) (hilu, 1994). finger millet is a climate-resilient (kumar et al., 2017) and highly adapted to adverse agro-ecological conditions with minimal inputs, produced on marginal land where other crops cannot perform, and tolerant to acidic soil (upadhyaya et al., 2007; gull et al., 20014) . finger millet is largely produced and consumed by marginalized inhabitants of semi-arid region of asia and africa; and it helps subsistence farmers with additional income from the grain sales (dida et al., 2007). finger millet is an important staple food crop widely grown in ethiopia. the crop was produced by 1,765,407 farmers on 456,057.31 hectares of land with total production of 1,030,823.15 tons in 2017/18 meher cropping season. finger millet production accounted 3.6% of 80.71% cultivated land for cereal crops and 3.37% of 87.48% cereal crops production (csa, 2018). its grain is gluten-free; rich in calcium, fiber, iron, and has excellent malting qualities (chandrashekar, 2010; pradhan et al., 2010; gupta et al., 2014). research has shown that finger millet diets are rich in protective against several degenerative diseases such as diabetes, cardiovascular diseases, and few types of cancers, metabolic syndrome and parkinson’s disease (fardet et al., 2008). the national average yield is 2.26 t ha-1 (csa, 2018) lower than the potential yield of the crop. limited availability of stable high yielding and disease tolerant finger millet varieties is one of the major production constraints in the country. accordingly, bako agricultural research center evaluated different accessions of finger millets collected from different regions of the country categorized in to seed color class to identify stable, high yielding, and disease-resistant varieties in order to address farmers’ needs. therefore, “diga-2” finger millet variety was released for the test environments (bako and gute) and similar agroecologies of the country. dagnachew et al. east african journal of sciences volume 14 (2) 175-180 176 2. varietal origin and evaluation diga-2 (acc. bkfm0010) finger millet (eleusine coracana sub.spp. coracana) variety was obtained from ethiopian institute of bio-diversity (ebi). originally, it was collected from beneshangul gumuz regional state, western ethiopia. this variety and the other blackseeded genotypes were evaluated against the standard check, degu, for three consecutive years (2014 2016) at bako and gute research stations. 2. agronomic and morphological characteristics the released variety, diga-2 (acc. bkfm0010) is characterized by loose finger type, black seeded, average 1000 seeds weight of 3 grams, an average plant height of 103.61 cm and 104 mean days to flower (table 5). the released black seeded finger millet variety diga-2 is relatively stable with optimum mean grain yield (2.38 t ha-1), (33.7 %) yield advantage over the standard check, degu (tables 1 and 5). 3. yield performance the released black seeded finger millet variety diga-2 (acc. bkfm0010) is relatively stable with optimum mean grain yield (2.38 t h-1) and having (33.7 %) yield advantage over the standard check (1.78 t ha-1) degu. genotypes (bkfm0020 and bkfm0006) among tested genotypes were better in average grain yield but are not stable and had agronomic defects like logging (table 1). table 1. genotypes mean grain yield (ton ha-1) over location across years. mean grain yield (t ha-1) genotype bako gute mean bss 2014 2015 2016 2014 2015 2016 215984 1.136 3.205 1.821 1.841 1.406 2.146 1.93 2 216035 1.301 2.531 2.177 2.557 1.657 2.535 2.13 1 216045 1.042 3.064 1.412 2.304 1.374 2.67 1.98 1 bkfm0001 1.469 3.342 2.184 3.059 1.204 2.427 2.28 1 bkfm0006 1.814 3.263 2.562 2.776 2.015 2.886 2.56 1 bkfm0010 1.196 3.419 2.247 3.228 1.676 2.508 2.38 1 bkfm0014 1.578 2.979 1.748 2.776 1.338 1.813 2.04 2 bkfm0020 2.56 3.549 2.721 2.889 2.446 2.41 2.78 1 bkfm0023 1.617 3.367 1.984 3.327 1.788 1.9 2.33 2 bkfm0024 0.938 2.92 1.669 3.189 1.458 2.44 2.10 2 degu 1.59 2.636 1.926 1.526 1.343 1.628 1.78 2 local 0.972 2.68 2.264 1.723 1.313 2.544 1.92 2 mean 1.435 3.127 2.06 2.6 1.535 2.325 2.18 lsd 0.579 0.794 0.712 0.977 0.7692 0.945 0.796 cv(%) 23.8 15 20.3 22.2 29.2 23.9 f-value ** * * ** ns ns note: bss = blast severity score made at 1-5 scale; cv = coefficient of variation and lsd = least significant difference. 4. stability and adaptability performance eberhart and russell (1966) model anova revealed highly significant for mean square due to variety (table 2). diga-2 (acc. bkfm0010) showed regression coefficient (bi) relatively closer to unity, so that the variety is relatively more stable and widely adaptable than other genotypes (table 3). the gge biplot analysis showed that the variety fell in the second concentric circle away from vertical mean line and closer to the stability line crossing the origin (figure 2), indicating its high yield potential and relative stability compared to the other genotypes (yan, 2001). similarly, the ammi analysis revealed that diga-2 attained ipca values relatively close to zero (table 4) and hence are better stable and widely adaptable genotype across locations with higher yield potential (figure 1). dagnachew et al. ‘diga-2’ finger millet variety registration 177 table 2. analysis of variance for grain yield using the eberhart and russell regression model. source df ss mean square or ms total 215 38.620 variety 11 5.570 0.506** env.+ in var. x env. 60 33.050 0.551 env. in linear 1 25.202 var. x env. (linear) 11 2.029 0.184ns pooled deviation 48 5.819 0.121 note: grand mean = 2.18; r2 = 0.8239; coefficient of variation = 24.51% and ** = *, ** = significant at p < 0.05 and p < 0.01 levels, respectively. table 3. regression coefficient (bi) and squared deviation from linearity of regression (s2di) by the test genotypes revealed using eberhart and russell model. genotype regression coefficient and bi squared deviations from regression or s2di grain yield (t ha-1) local 0.8531 0.1408 1.92 bkfm0020 0.7416 0.0385 2.78 bkfm0023 1.1115 0.0702 2.34 215984 1.0165 0.0095 1.93 bkfm0006 0.8176 -0.0661 2.56 bkfm0024 1.2493 0.0580 2.10 bkfm0010 1.0578 -0.0284 2.38 216045 1.1817 0.1351 1.91 bkfm0014 0.9784 -0.0117 2.05 bkfm0001 1.2590 -0.0387 2.28 216035 0.7171 -0.0184 2.13 degu 0.4956 0.0358 1.78 note: standard error of beta = 0.2403. table 4. analysis of variance for additive main effects and multiplicative interaction (ammi) for yield stability of black seeded finger millet genotypes from 2014-2016 at bako and gute research station. source df ss ms % gxe cumulative interaction explained (%) environment 5 75.606 15.121** genotype 11 16.710 1.519** genotype x envt. interaction 55 23.544 0.428* ipca i 15 11.394 0.760 ** 48.39 48.39 ipca ii 13 6.740 0.518 * 28.63 77.02 ipca iii 11 3.276 0.298ns 13.91 90.93 residual 132 35.702 0.270 note: grand mean = 2.18; r2 = 0.7719; coefficient of variation (cv, %) = 23.98%; *, ** = significant at p < 0.05 and p < 0.01 levels, respectively. 5. reaction to major diseases diga-2 (acc. bkfm0010) finger millet variety showed tolerant to blast (magnaporthe oryzea) which is the major production constraint of finger millet at national level, but much severe in western oromia. 6. conclusion diga-2 (acc. bkfm0010) finger millet (eleusine coracana sub.spp. coracana) variety gave relatively high grain yield, showed wider adaptability and stable performance than the standard check and the other pipeline varieties evaluated. in general, eberhart and russell, gge biplot analysis and ammi model analysis results revealed that diga-2 (acc.bkfm0010) is a stable and high yielding (2.38 ton ha-1) finger millet variety with 33.7% yield advantage over the standard check variety, degu (1.78 ton ha-1) and also tolerant to blast disease. therefore, it was officially released for wider production in west oromia (bako, and gute) and areas with similar agro-ecologies. dagnachew et al. east african journal of sciences volume 14 (2) 175-180 178 table 5. agronomic/morphological characteristics of diga-2 (acc.bkfm0010) finger millet variety. characteristic parameter description of agronomic/morphological characteristics variety name diga-2 (acc.bkfm0010) adaption area: western oromia (bako, gute and similar agro-ecologies altitude (meter above sea level) 1200−2300 rainfall (mm) 1000−1300 seed rate (kg/ha) 15 kg for row planting and 25kg for broadcasting spacing 40 cm between rows planting date early june fertilizer rate (kg ha-1) dap 100 kg ha -1 at planting urea 65 kg ha-1 split application (half at planting and half at 35 days after emergence) days to flowering 104 days days to maturity 164 days finger type loose fingers per ear 7 finger length (cm) 10.6 thousand seed weight (g) 3 plant height (cm) 103.6 seed color black growth habit erect crop pest reactions tolerant to major finger millet diseases (leaf and head blast) yield (t ha-1) research field 2.24−3.42 farmers field 2.32−2.98 year of release 2018 breeder seed maintainer bako agricultural research center (barc/oari) figure 1. ammi biplot showing genotypes grain yield stability and preferential. dagnachew et al. ‘diga-2’ finger millet variety registration 179 figure 2. gge biplot based on grain yield for the 12 genotype showing the relationship among environments. 7. acknowledgments the authors acknowledge oromia agricultural research institute for funding the research. bako agricultural research center management and all staff members of the cereal crops technology generation team members are highly acknowledged for their commitment in implementing the research works, experimental field management, and data collection. 8. references chandrashekar, a. 2010. finger millet: eleusine coracana. advances in food and nutrition research, 59, 215–62. csa (central statistical agency). 2018. ethiopia central statistics agency agricultural sample survey 2017/18 report on area and production of major crops. addis ababa, ethiopia. dida, m., srinivasachary, r.s., bennetzen, j., gale, m. and devos, k. 2007. the genetic map of finger millet, eleusine coracana. theoretical and applied genetics, 114, 321–332. eberhart, s. and russell, w. 1966. stability parameters for comparing varieties. crop sciences, 6, 36–40. fardet, a., rock, e. and remesy, c. 2008. is the in vitro anti-oxidant potential of whole-grain cereals and cereal products well reflected in vivo. journal of cereal science, 48: 258–276. gull, a., jan, r., nayik, g.a., prasad, k. and kumar, p. 20014. significance of finger millet in nutrition, health and value added products. a review. journal of environtal science, computer science and engineering and technology, 3: 1601–1608. gupta, s., gupta, s.m., gupta, a., gaur, v.s. and kumar, a. 2014. fluctuation of dof1/dof2 expression ratio under the influence of varying nitrogen and light conditions: involvement in differential regulation of nitrogen metabolism in two genotypes of finger millet (eleusine coracana l.). genetics, 546, 327–335. hilu, k.w. 1994. validation of the combination eleusine coracana subspecies africana. phytologia, 76(5): 410–411. kumar, s.v, sajeevkumar, v., george, j. and kumar, s. 2017. enhancing properties of polyvinyl alcohol film using sorghum starch nanocrystals – a cost effective filler from natural source, defence life. science journal, 2(2): 169–177. pradhan, a., nag, s. and patil, s. 2010. dietary management of finger millet [eleusine coracana (l). gaerth] controls diabetes. current science, 98(6): 763–765. upadhyaya, h., gowda, c. and reddy, r. 2007. morphological diversity in finger millet germplasm introduced from southern and eastern africa. sat ejournal, 3(1): 1–4. yan, w. 2001. gge biplot a windows application for graphical analysis of multienvironment trial data and other types of two-way data. agronomy journal, 93(5): 1111–1118. dagnachew et al. east african journal of sciences volume 14 (2) 175-180 180 ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (2) 163-168 licensed under a creative commons *corresponding author. e-mail: lemdeb@yahoo.com attribution-noncommercial 4.0 international license. short communication a robust method of computing the annual rate of land use/land covers change in landscapes debissa lemessa ethiopian biodiversity institute, addis ababa, ethiopia abstract background: several earlier studies have used different formulae to compute the annual rates of land use/land covers changes in landscapes. moreover, the magnitudes of the land use changes from two time points (i.e., initial and recent) only have been used to compute the annual rates. however, the use of different formula by itself is confusing and the failure to take into account the instantaneous changes in magnitude of the land use changes from the intermediate time points along the time period may lead to either overestimation or underestimation of the annual rates. objective: a formula to compute the annual rate of change in land use/land cover in a robust method was suggested based on the property of the function of instantaneous change in slope and law of compound interest in economics. materials and methods: the property of instantaneous changes in slope was integrated with the formula of compound interest in economics to derive the formula of calculating the interest rate of change in land use. with the application of this approach, the differential effects of the drivers of land use change along long temporal scale can be taken into account by converting the magnitude of the changes into change factors. here, data are “scaled” to change factors from the ratios of the mid points (tangent lines) to the consecutive intermediate initial time points along the time period and these change factors are again averaged over number of time intervals of change detection to enhance the precision of calculating annual rates. result: the annual rate of change in land use should be computed as, . conclusion: for both short and long time periods, the present formula can be applied as standard and such computation is an ideal input for planning biodiversity conservation and development strategies. keywords: change factors; compound interest; instantaneous changes; time period 1. introduction land or natural landscapes have been altered throughout human history due to the conversions for agricultural production, industrialization and settlements among others (prasad et al., 2010; ganasri et al., 2013). land use/land cover refers to the ecosystem functions and services, while land cover is described based on vegetation cover, wetlands and grass coversthe observed biophysical features in human-modified landscapes (lillesand et al., 2004; feranec et al., 2007). the drivers of the land use/land cover changes are most often categorized as proximate causes including extensive agriculture and over exploitation of forest resources (i.e., wood extraction for timber production, fire wood and charcoal and construction) and underlying causes such as population growth, inappropriate institutional arrangements, weak law enforcements and political instability (geist and lambin, 2002). as a result, the current scenario shows that the human-modified landscapes are heterogeneous, fragmented and comprised of different land use /land cover types and hence we need to understand the rates of changes and the consequences on biodiversity. the changes in land use have both positive and negative impacts on biodiversity conservation and sustainable utilization of the resources and hence, management thereof needs effective land use planning and policies. to this end, understanding of the processes of the land use changes and at what rates these changes are taking place in explicit and implicit ways could be one of the key inputs for policy makers in designing conservation and development strategies (chauhan and shailesh, 2005; papastergiadou et al., 2007; lin et al., 2009). however, different authors have been using different formulae to calculate the annual rate of changes of land use/land covers (see abate shiferaw and singh, 2011; tesfa worku meshesha et al., 2016; krios tsegay deribew and desalegn wana dalacho, 2019). similarly, students who have been studying for their masters and phd in thematic areas of debissa east african journal of sciences volume 14 (2) 163-168 164 the dynamics of landscapes are also using various formulae and report in their theses in either within the same or in different universities (personal observation). besides the confusions emanating from using different formulae, these formulae also yield different values of rates. the nature of the land use change dynamics often take continuous exponential pattern with instantaneous trend and comprise outliers. nevertheless, the previous formulae do not take into account these factors and such failure may cause either overestimations or underestimations and this can lead to wrong conclusions either in area of academia or in planning development and conservation activities. in relation to this, puyravaud (2003) from india has standardized the calculation of the annual rate of deforestation from the formula adapted by fao (1995) which is based on the compound interest law in economics (the formulae were shown in results section for comparison purposes). these two formulae have been widely used, but have shortcomings for substantial reasons: (1) were limited only to two time points (the initial and recent) from the time period and cannot be applied to calculate the annual rate of change from instantaneous changes along time period, (2) the farmers decisions and the associated magnitude of land conversion is continuing process and vary from time to time and as a result the changes are instantaneous in nature along time periods, and (3) computing the annual rate from only two points of land use changes undermines the effects of the outliers and intermediate changes and may not indicate the actual rate of change on the ground due to either overestimation or underestimation of the annual rates. the land use changes are exponential in nature and exhibit a continue change and hence the magnitude of the change factors need to be averaged from various time points and from the midpoints (tangent lines) of the instantaneous changes of slopes (land use/land cover). therefore, the aim of this short communication is to suggest a formula on how to compute the annual rate of land use change in a robust way by take into account the nature of the instantaneous changes in land use and based on the basics of the compound interest rate and average rate of change in slope in geometry. 2. materials and methods in geometry, the slope or rate of change between two points is calculated as , however, when there are several changes in slopes over long time, the formula will be extended to . in this case, the rate of slope change is calculated from one point with the assumption that approaches zero when scant lines become closer to tangent lines in the curve, i.e., . here, the slopes from various tangent lines (mid points) are averaged before converted to change factors or change of slopes. let us assume that we have analyzed change detection for certain land use/land cover types over certain time periods and changes are quantified as . then, the average of changes will be calculated from the intermediate points as . we can easily understand from this method that the annual rate of land use/land covers changes need to be calculated integrating the logic of instantaneous changes with the formula of compound interest in economics ( ), where, is the recent capital, the initial principal capital, , interest rate, the time periods or how many times within a year when interest rates are calculated. unlike the calculation of interest rate ( in financial system, the rate of land use change is rather computed per year than per periods within a year and, hence, contextually, this formula can be adjusted to , where, is a fixed annual interest rate or “annual rate of change” in land use/land cover context and is the total time period of the change detection. thus, = and with integration, this becomes . when the concept of instantaneous rate of changes (i.e., calculating the average rate of slopes) is applied into this formula, the change factor is computed from mid points (the tangent lines) (figure 1) rather than subtracting the initial value from the recent value of change. based on the above example, is computed as = , where, is the number of time points of the time period and the division by is to take the average of the mid points. debissa computing the annual rate of change in land use/land covers 165 figure 1. the hypothetical line graph illustrating how the change of the land use (e.g. forest) vary and the importance of taking into account the instantaneous changes or change factors of the intermediate time intervals over time period (i.e., five decades). 3. results the following formula (eq. 1) is, therefore, suggested to robustly compute the annual rate of land use/land cover change as, (eq. 1) where, =the initial amount of land use change, = the mid points of the amount of land use changes ( =number of mid points), = the recent amount of land use change, the number of time points from the time period for which the change detection is computed, and =total time period of the change detection. the can be computed in r statistical program using the script shown in box a. box a. the script to compute the annual rate of land use/land cover changes in landscapes in r statistical program. computing the annual rate (%) in change of land use in r-statistical program eq. ( a) where, = the initial amount of land use change, = the mid points of the amount of land use changes ( = number of mid points), = the recent amount of land use change, the number of time points from the time period for which the change detection is computed, and = total time period of the change detection. debissa east african journal of sciences volume 14 (2) 163-168 166 4. discussion the present formula can be applied as standard to compute rates of land use/land covers changes over both short and long time periods, and such computation is an ideal input for planning biodiversity conservation and development strategies. the robustness such computations was illustrated using both hypothetical graphs and by taking examples of the actual data. moreover, the rates computed with this present formula are compared for its intuitiveness with the formulae used by puyravaud (2003) and fao (1995). let us assume that we wanted to understand the annual rate of forest land use change over the last five decades from 1980 to 2020 in a certain area. then, to apply the formulae adapted by fao (1995), −1) 100 (eq. 2) and puyravaud (2003), (eq. 3) we have to take the value of the forest land use from the initial time point of 1980 and from the recent time point of 2020. such kinds of calculations assume that the drivers and the associated magnitude of change in forest land use are “constant” in the intermediate time points or over the time period of 40 years, which in reality are not the case. on the contrary, the variation in the changes of the forest land use during these five decades can be supposedly illustrated as shown in figure 1. moreover, these facts can be further elaborated by comparing the rates applying these two formulae and the current formula ( ). as we can see from the hypothetical data in table 1, the rates calculated using higher when compared with rate from most likely, the rates for are overestimated since both do not take the average of the changes from the initial and recent time points before converting to change factors. moreover, as can be clearly observed from figure 2 in which the annual rates were computed for five land use types (see table 2), the annual rates calculated using are less strongly correlated ( = 0.87) with coefficient of variation when compared with that of as a result, at lower coefficient of variation, the annual rates computed are similar for however, when coefficient of variation get higher, significant variations are observed between and (see table 2). here, applying the later formulae, for the effect of the outliers are not minimized and the change factors from the intermediate land use changes are not optimized either underestimations or overestimations may occur in the annual rate of changes in land use. on the contrary, assumes that the landscape variableswhether biological or biophysical, are in dynamic process in mosaic landscapes in spatial and temporal context (sokal and rohlf, 1969; gotelli and ellison, 2004) and does not reach exponential decay as previous formulae assume. 5. conclusion and recommendation altogether, with the application of besides its advantage for computing the annual rate of change in a robust way and avoids wrong conclusions (sambou et al., 2015). moreover, the present formula can be used as a standard and avoids the confusions that arise from using different formulae to compute the annual rates of land use/land cover changes in human modified landscapes. debissa computing the annual rate of change in land use/land covers 167 table 1. comparing the rate of forest land use changes using only the two time periods from the initial (1980) and the recent time period (2020), unit is in percentage per year. land use 1980 1990 2000 2010 2020 1/(t2 −t 1 ) −1)100 area (ha) area (ha) area (ha) area (ha) area (ha) forest 8040 5060 3070 4436 1806 -3.66 -3.73 -2.96 table 2. the annual rate of land use changes are calculated for lr q and r. the land use data analyzed is from the satellite images of 1973, 1986, 2000 and 2018 in southwest ethiopia (resolution = 3030m). no land use 1973 1986 2000 2018 data dispersion (cv) in (%) area (ha) area (ha) area (ha) area (ha) 1 forest 82054 70123 63369 44588 24.09 -1.14 -1.35 -1.36 18.4 19.3 2 shrub land 8785 9581 8364 5955 19.11 -0.73 -0.86 -0.86 17.8 17.8 3 wetland 6316 7224 6929 4886 16.40 -0.55 -0.57 -0.57 3.64 3.64 4 crop land 8170 18542 28567 46440 64.08 1.83 3.94 3.86 115.3 110.93 5 bare land 7 1044 46 65 173.12 8.21 5.08 4.95 313 326 data organized from fikiru belete (2020). debissa east african journal of sciences volume 14 (2) 163-168 168 6. acknowledgements i thank prof. kristoffer hylander (landscape ecologist), dr. fekadu lemessa (mathematical statistician), mr. tariku geda (a gis expert) and anonymous reviewers for their insightful comments which obviously have enhanced the clarity of this short communication. finally, i extend my gratitude to dr. melesse mariyo and mr. fikiru belete for sharing me their land use/land cover data that i used for statistical validation. 7. references abate shiferaw, singh, k.l. 2011. evaluating the land use and land cover dynamics in borena woreda of south wollo highlands, ethiopia. east african journal of sciences, 2(1): 69–104. chauhan, h.b., shailesh, n. 2005. landuse/land cover changes near hazira region, gujarat using remote sensing satellite data. journal of indian society of remote sensing, 33: 220–227. fao (food and agriculture organization). 1995. forest resources assessment 1990. global synthesis, fao, rome. feranec, j., hazeu, g., christensen, s. et al. 2007. corine land cover change detection in europe (case studies of the netherlands and slovakia). landuse policy, 24: 234–247. fikiru belete. 2020. land use/land cover dynamics and perception of the local communities in bita district, southwest ethiopia. m.sc. thesis, kotebe metropolitan university, addis ababa, ethiopia. ganasri, b.p., raju, a., dwarakish, g.s. 2013. 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e.s., retalis, a., kalliris, p., georgiadis, t.h. 2007. land use changes and associated environmental impacts on the meditteranean shallow lake stymfalia, greece. hydrobiologia, 584: 361–372. prasad, r.c.p., rajan, k.s., dutt, c.b.s., roy, p.s. 2010. a conceptual framework to analyze the landuse/land cover changes and its impact on phytodiversity – a case study of north andaman islands india. biodiversity and conservation, 19: 3073–3087. puyravaud, j.p. 2003. standardizing the calculation of the annual rate of deforestation. forest ecology and management, 177: 593-596. sambou, s., lykke, a.m., sambou, h., guiro, i., sambou, b., mbow, ch. 2015. land use-land cover change and drivers of deforestation in the patako protected area of center-west of senegal. american journal of environmental protection, 4: 306−317.https://doi.org/10.11648/j.ajep.201504 06.17. sokal, r.r., rohlf, f.j. 1969. biometry, the principles and practice of statistics in biological research, 2nd edition, w.h. freeman and company, san francisco. tesfa worku meshesha, tripathi, s.k., khare, d. 2016. analyses of land use and land cover change dynamics using gis and remote sensing during 1984 and 2015 in the beressa watershed northern central highland of ethiopia. modeling earth systems and environment 2:1−12, https://doi.org/10.1007/s40808-016-0233-4. ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (2) 169-174 licensed under a creative commons *corresponding author. e-mail: geletarabi@gmail.com attribution-noncommercial 4.0 international license. registration of a new triticale variety: ‘kombolcha’ geleta gerema1*, kassa mamo3, chemeda birhanu1, megersa debela1, kebede dessalegn1, girma chemeda1, megersa kebede1, bodena gudisa1, hailu feyisa1, girma mangistu2, dagnachew lule2, and gudeta bedada1 1bako agricultural research center, p.o. box 03, bako, west showa, ethiopia 2oromia agricultural research institute, addis ababa, ethiopia 3ambo agricultural research center, west showa, ethiopia abstract background: triticale (x-triticosecale wittmack) is a hybrid of wheat (triticum sp.) and rye (secale sp.) it combines yield potential and grain quality of wheat with the diseases and environmental tolerance including adaptability to marginal soils, diseases resistance and low-input requirements of rye. the crop has demonstrated high yield potential under marginal growing conditions and could a very attractive alternative for raising cereal production in the globe, involves ethiopia. objective: to evaluate and release stable high yielding and disease resistant/tolerant triticale variety for the western highland of oromia and other similar agro-ecologies material and methods: twelve triticale genotypes including the standard check “moti” were evaluated across two locations for three years (2015-2017). eventually, two promising genotypes, “acc 2012 ms #51 and acc.2012 ms #59” were selected and promoted to variety verification trail with the standard check ‘’moti” during the 2018/19 cropping season. the national variety release technical committee evaluated the two candidate varieties both at gedo and shambu on research stations and farmers’ fields. results: among the two evaluated varieties, ‘kombolcha’ is well adapted to altitudes ranging between 2244 and 2784 meters above sea level and characterized by amber seed color, longer panicle and gave high seed yield (6184.8 kg ha-1) and stable performance across years and locations. it has about 13% yield advantage over the standard check variety, “moti”. the variety is also resistant to major diseases such as steam rust (pucinia graminis f.sp. tritici), yellow rust (puccinia striiformis f.sp. tritici) and septoria tritici (mycosphaerella graminicola). conclusions: “kombolcha” (acc. 2012 ms #51) is released for the highlands of western oromia and similar agro-ecologies for its stable and high grain yield, and resistant to major diseases. therefore, farmers in western highlands of oromia and similar agro ecologies particularly those inhabiting marginal and acid prone areas can produce “kombolcha” variety with its full management recommendation. keywords: disease resistance; genotype; grain yield; moti; triticosecale wittmack; yield stability 1. introduction triticale (triticosecale wittmack, 2n = 6x = 42; bbaarr.) is a hybrid of wheat (triticum sp.) and rye (secale sp.) which was developed by using conventional plant breeding methods followed by embryo culture (guedes-pinto et al., 2001). wheat was used as the maternal plant and rye was used as the paternal plant. triticale obtained the best characteristics of the two crops. wheat is characterized by high yield and better grain quality (meng, 2009). but rye has greater diseases resistance and better tolerance to environmental stress (crespo-herrera et al., 2017). triticale has high feeding value and superior adaptation to stress conditions such as drought, acidic soils, excess moisture and low soil fertility where other crops produce low yields and/or are poorly adapted (fao, 2004). triticale has a more vigorous root system than wheat, barley or oats. its roots bind light soils and extract more nutrients from the soil. the vigorous root system of triticale make growing this plant attractive soils with low fertility status particularly light-textured where crops are required to outcompete weeds for growth resources (gobeze et al., 2007). triticale has demonstrated high yield potential even under stress environmental conditions in ethiopia and could be a very attractive alternative for increasing cereal production in the country. it was reported that triticale increased farmers’ net benefits compared to wheat and barley in farta district of amhara regional state in ethiopia (mesfin, 2012). in ethiopia, the grain of triticale is used for human food, while the straw is used for animal feed, roof thatching, and as bedding material. in certain areas with marginal and acidic soils in the country in general and western ethiopia in particular, triticale is one of the most promising newly introduced crop species that could show superior adaption. research results in areas with acidic and marginal soils of western ethiopia have shown that triticale can be an excellent alternative crop to wheat and barley (bakoarc, 2019). there is no report in ethiopia that indicates area coverage and production of triticale geleta et al. east african journal of sciences volume 14 (2) 169-174 170 anywhere in the country. however, there have been already improved triticale varieties developed and released for production in different agro ecologists in the country. in the last few decades, bako agricultural research center developed and released two improved triticale varieties (abdissa and moti), which are adapted to marginal and acidic soil areas to which other crops are poorly adapted and produce low yields. in foodinsecure countries like ethiopia, climate change is expected to reduce yields through increased biotic and abiotic stresses. concerns about such effects have prompted widespread efforts to identify varieties that may provide genetic variability for adaptation to climate change. recently, the third variety, ’kombolcha’ has been released, which is well-adapted in the wide agro-ecology of western ethiopia and other areas with similar agroecology of ethiopia. 2. varietal origin and evaluation kombolcha (acc 2012 ms #51) along with 11 genotypes were obtained from debreziet agriculture research center of the ethiopian institute of agriculture research. the genotypes were evaluated along with the standard check variety, “moti”, across two locations (shambu and gedo) from 2015-2017. two genotypes “acc 2012 ms #51 and acc.2012 ms #59” were selected as candidate varieties based on a combined data analysis of variance and mean performances comparison of genotypes. the two most promising candidate varieties and the standard check variety, “moti”, were eventually promoted to a variety verification trial. the candidate varieties and standard check variety were planted in plots with a size of 10 m x 10 and evaluated by the national variety release technical committee at two locations during the 2018/19 cropping season. finally, the national variety release technical committee selected “acc 2012 ms #51” genotype for release. acc 2012 ms #51 has high biomass, long panicle length, better yield advantage, and good resistance to major diseases like steam rust (pucinia graminis f.sp. tritici), yellow rust (puccinia striiformis f.sp. tritici) and septoria tritici (mycosphaerella graminicola). 3. varietal characteristics kombolcha variety significantly out-yielded moti (the standard check variety) and the other candidate (acc. 2012 ms #59) in terms of number of productive tillers, biological yield, and 1000 seeds weight. the new variety has 6.12%, 11.96%, and 12.74% longer panicles, heavier 1000 seed weight, and higher biological yield than moti (the standard check variety), respectively (table 1). number of spikes per unit area, 1000-grain weight, and biological yield are assumed to be the main yield components (mollasadeghi et al., 2011). the agronomic characteristics of the variety are indicated in details below (tables 1 and 3). kombolcha variety could be adapted under stress environments such as acidic soil and low soil fertility where other crops produce low yields and are adapted poorly adapted. hinojosa et al. (2002) and pfeiffer (1994) reported that triticale could be adapted to harsh, low-input, sustainable farming systems and it is rapidly expanding in several production systems. the new variety could be resistance to lodging and have the ability to withstand high fertility/nitrogen input. the newly released variety, ’kombolcha’ produced seed yield ranging between 1906.7 to 8346.7 kg ha-1 over the three years of production at the two locations while “moti” variety produced seed yield ranging between 1730 and 8196.7 kg ha-1 (table 2). the new variety, ’kombolcha’ has a mean seed yield of 6184.78 kg ha-1 which was higher by about 13% and 3.1% than the seed yields obtained from moti (the check variety) and the other candidate variety acc. 2012 ms #59, respectively (table 2). the newly released variety produced 3900 to 5100 kg ha-1 seed yield on farmers field as compared to moti, which produced 2940 to 4167.6 kg ha-1 as well as the newly released variety and the other candidate variety (acc. 2012 ms #59), which produced a seed yield of 3145.5 to 4320.5 kg ha-1 (tables 3). the average grain yield of the ’kombolcha’ variety on farmers’ fields (4500 kg ha-1) is higher compared to the world’s average yield (3660 kg ha-1) (fao, 2018) as well as that of some ethiopian varieties (2466.5 kg ha-1) (aemiro bezabih et al., 2019) . table 1. mean values of agronomic performances of two triticale candidate and standard check varieties in shambu and gedo districts of western ethiopia, during the 2015-2017 cropping seasons. trait genotype acc.2012 ms #51 (bariso variety) acc. 2012 ms #59 moti (standard check variety) maturity (day) 122.2 123.2 122.8 plant height (cm) 117.8 103.5 103.7 panicle length (cm) 10.4 9.7 9.8 1000 grain weight (g) 49.6 47.0 44.3 biomass(kg/ha) 35, 340.4 33, 234.7 31, 345.0 grain yield (kg ha-1) 6108.9 5573.4 5406.7 yield advantage (%) 13.0 3.1 geleta et al. triticale: ‘kombolcha’ variety registration 171 table 2. mean grain yield (kg ha-1) of two triticale candidate and standard check varieties in shambu and gedo districts of western ethiopia, during the 2015-2017 cropping seasons. year location genotype acc. 2012 ms #51 (bariso variety acc. 2012 ms #59 moti (standard check variety) shambu 6107.0 6587.0 4813,0 2015 gedo 8346.7 6250.0 6093.3 mean 7226.9 6418.5 5453.2 shambu 8233.3 5966.7 8196.7 2016 gedo 5830.0 6490.0 5556.7 mean 7031.7 6228.4 6876.7 shambu 6685.0 6040.0 6049.9 2016 gedo 1906.7 2106.7 1730.0 mean 4295.9 4073.4 896.5 mean of three years 6184.8 5573.4 5406.6 sd 2347.53 1715.56 2990.94 cv (%) 27.3 29.7 32.0 note: sd = standard deviation and cv (%) = coefficient of variation. table 3. agronomic and adaptation characteristics of “bariso” triticale variety in comparison with the standard check and other candidate varieties in shambu and gedo districts of western ethiopia, during the2015-2017 cropping seasons. characteristics variety/genotype bariso variety (acc. 2012 ms #51) acc. 2012 ms #59 moti moti (standard check variety) adaptation area altitude (m a.s.l.) 2244–2784 2244–2784 1800–2700 rainfall (mm) > 800 > 800 >600 seed rate (kg ha-1) 150 150 150 fertilizer rate nps (kg ha-1) 100 100 100 urea (kg ha-1) 100 100 100 days to maturity 121–123.4 121.6–125.9 120.7–124.9 1000 seed weight (g) 47.5–51.7 45–49 41.1–47.5 plant height (cm) 113.9–121.7 102.5–105.8 101.5–105.9 panicle length (cm) 8.8–11. 8.6–10.9 8.7–10.9 crop pest reaction tolerant to pests tolerant to pests moderate seed yield research field (kg ha-1) 1906.7–8346.7 2106.7–6587 1730–8196.7 farmers field (kg ha-1) 3900–5100 3145.5-4320.5 2940.4–4167.6 year of release 2019 2012 4. yield stability of the new variety the total variation in grain yield for the gei was 74.56%, with pc1 and pc2 accounting for 49.48% % and 25.10%, respectively (fig1).this shows that most of the grain yield variation was due to genotypes and environments. the result indicates that there was a great variation among the environments in terms of grain yield. consistent with this result, kendal and sayar (2016) reported that there was a considerable variation among the environments in grain yield of triticale genotypes. the gge biplot analysis revealed both candidates (2012 ms #51 and 2012 ms #59) exhibited higher stability for yield across the two locations over the three growing years. mainly, the new variety, ‘kombolcha (acc. 2012 ms #51) represented by the number four was relatively close to the ideal environment in the concentric circle and near average environment axis, suggesting their potential for wider adaptability with better gain yield performances (figure 1). the two principal components accounted for 74.56% of the total variation of which pc1 accounted for 49.48% and pc2 accounted for 25.10% of the total variation. geleta et al. east african journal of sciences volume 14 (2) 169-174 172 figure 1. gge biplot depicting the yield stability of tested genotypes in shambu and gedo districts of western ethiopia, during the 2015-2017 cropping seasons [1 = 2012 ms #110, 2 = 2012 ms #100, 3 = 2012 ms #102, 4 = kombolcha/2012 ms #51, 5 = 2012 ms # 26, 6 = 2012 ms # 85, 7 = 2012 ms # 59, 8 = 2012 ms #62, 9 = 2012 ms #88, 10 = 2012 ms # 81, 11 = 2012 ms #101 and 12 = standard check variety (moti)] over six test environments (two locations over three years). table 4. the accession and origin of the genotypes used for the study in shambu and gedo districts of western ethiopia, during the 2015-2017 cropping seasons. number accessions source 1 2012 ms #110 debreziet arc/cimmyt 2 2012 ms #100 debreziet arc/cimmyt 3 2012 ms #102 debreziet arc/cimmyt 4 2012 ms #51 debreziet arc/cimmyt 5 2012 ms #26 debreziet arc/cimmyt 6 2012 ms #85 debreziet arc/cimmyt 7 2012 ms #59 debreziet arc/cimmyt 8 2012 ms #62 debreziet arc/cimmyt 9 2012 ms #88 debreziet arc/cimmyt 10 2012 ms #81 debreziet arc/cimmyt 11 2012 ms #101 debreziet arc/cimmyt 12 moti (st.check) debreziet arc/cimmyt 6. reaction to major diseases each candidate was evaluated for its response to rusts and septoria leaf blotch in the field. as a result, the new variety, ’kombolcha’ was found to be resistant to moderately resistant to three rust diseases. the variety was resistant to yellow rust (0–5 r) and moderately resistant to stem rust (0–5 mr) while the standards check variety, “moti” was found to be moderately resistant to the diseases. the other candidate variety (acc. 2012 ms #59) was found to be moderately resistant to susceptible to the diseases (table 5). the new variety also showed a low score for septoria tritici, which is comparable with check (moti) and the other candidate (table 5). in general, both candidates have good resistance to major diseases. in comparison to wheat, triticale appears to have good resistance to major wheat diseases and pests including rusts (puccinia sp.) and septoria complex (mohammed and tegegn, 2019). developing resistant triticale varieties to major diseases such steam rust (puccinia graminis), yellow rust (puccina striiformis) and septoria tririci (mycosphaerella graminicola) is one of the major objectives of the geleta et al. triticale: ‘kombolcha’ variety registration 173 breeding program. therefore, release of the new variety ’kombolcha’ for use as a commercial variety in ethiopia is a testament to the progress made in making the breeding program a success. table 5. reaction of the new, the standard check, and the other triticale candidate varieties to stem rust, yellow rust, and septoria tritic in in shambu and gedo districts of western ethiopia, during the 2015-2017 cropping seasons. genotype diseases reaction stem rust yellow rust septoria tritici acc. 2012 ms #51 (“bariso”) 0–5mr 0–5r 14.3 acc. 2012 ms #59 5–10mr 0–15mr 12.5 moti (standard check variety) 10mr–30s 5mr–20s 12.3 table 6. major infection type classes for stem, leaf, and yellow rusts in shambu and gedo districts of western ethiopia, during the 2015-2017 cropping seasons. infection type host reaction symptoms i immune no visible infection r resistance necrotic/chlorotic areas with or without small sporulation mr moderately resistance small pustules surrounded by necrotic areas m moderately (resistance/resistance) combination of both mr and ms ms moderately susceptible medium sized pustules, no necrosis or some necrosis s susceptible a large pustules, no necrosis or chlorosis 6. conclusion “kombolcha” produced high yield, and it had a more stable performance in seed yield over locations and years than the standard check variety. the variety also showed a higher resistance to rusts and septoria tritici. therefore, it was released and recommended for cultivation in western ethiopia, but could be adopted for production in similar agro ecologies in the country. 7. acknowledgements we thank staff members of the cereal technology generation research team, bako agricultural research centers for their unreserved efforts in field trail management and data collection during the experimental period. we are thankful to oromia agricultural research institute for funding the research throughout the varietal development process. we also to thank the debrezeit agricultural research center and international center for agricultural research in the dry areas (icarda) for providing us with the germplasm. 8. references aemiro, b., getawey, g., alemu, l .2019. performance of triticale varieties for the marginal highlands of wag-lasta, ethiopia. cogent food and agriculture, 5:1. bakoarc. 2019. bako agricultural research center annual progress report. crespo-herrera, l.a., garkava-gustavsson, l., åhman, i. a.2017. systematic review of rye (secale cereale l.) as a source of resistance to pathogens and pests in wheat (triticum aestivum l.). hereditas, 154:14. food and agriculture organization (fao). 2004. triticale improvement and production. in: mohamed and gomez-macpherson, h. (eds.). fao plant production and protection paper 179. food and agriculture organization (fao). 2018. faostat yearly statistical book. rome, italy guedes-pinto, h., lima-brito, j., ribeiro-carvalho, c. and gustafson, j.p. 2001. genetic control of crossability of triticale with rye. plant breeding, 120: 27–31. gobeze, l., legese, h., daniel, m. 2007. effect of land preparation methods and spacing in growth and yield of cassava. proceedings of african society of crop sciences. pp.68–72. hinojosa, m.b., hede, a., rajaram, s., lozano del río, j. and valderrabano g.a. 2002. triticale: an alternative forage crop under rainfed conditions in chihuahua, mexico. pp. 22-29. in: arseniuk, e. (ed.). proceedings of the 5th international triticale symposium, radzikow, poland, 30 june5 july 2002. kendal, e. and sayar, m.s. 2016. the stability of some spring triticale genotypes using biplot analysis. the journal of animal and plant sciences, 26(3): 1018–7081. landuber, w., ayalew, h., woldeab, g. and mulugeta, g. 2015. yellow rust (puccinia striiformis) epidemics and yield loss assessment on wheat and triticale crops in amhara region, ethiopia. african journal of crop science, 4(2): 280–285. larter, e., shebeski, l., mcginnis, r., evans, l. and kultsikes, p. 1970. rosner, a hexaploid triticale cultivar. candian journal of plant science, 50: 122– 124. geleta et al. east african journal of sciences volume 14 (2) 169-174 174 meng, e., editor. 2009. economic analysis of diversity in modern wheat. crc press, boca raton. https://doi.org/10.1201/9780429061646. mesfin, a., legesse, b. and zerfu, e. 2012. analysis of economic impacts of triticale (triticosecale wittmack) adoption: the case of farta wereda, ethiopia. journal of scientific research and reviews. mohammedsani, z., tegegn, b. 2019. review on history and achievements of triticale breeding status in ethiopia. international journal of research studies in agricultural sciences. (ijrsas). 5( 9): 8– 13. mollasadeghi, v., imani, a.a. shahryari, r. and khayatnezhad, m. 2011. classifying bread wheat genotypes by multivariable statistical analysis to achieve high yield under after anthesis drought. middle east journal of science research. 7(2): 217– 220. https://doi.org/10.1201/9780429061646 ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(1): 69–76 licensed under a creative commons *corresponding author: yihe300@yahoo.com attribution-noncommercial 4.0 international license. alcohol content of hand sanitizers marketed in selected towns in eastern ethiopia yiheyis bogale*, deribachew bekana, and ayalew temesgen department of chemistry, college of natural and computational sciences, haramaya university, p.o. box 138, dire dawa, ethiopia abstract background: many generic brand hand sanitizers have been flooding the market because of the high surge in the demand for hand sanitizers around the globe due to rising prevalence of the covid-19 and increase in consumer awareness pertaining to personal hygiene worldwide. however, the quality of most sanitizers available on the market is questionable. objective: the purpose of this study was to determine ethanol concentration of commercially available ethanol-based hand sanitizers that are marketed in selected cities in eastern ethiopia (haramaya, dire dawa, and harar) and validate whether they meet the standard concentration recommended by world health organization (who) and recommend food and drug authority of ethiopia to check the quality of hand sanitizers marketed in all corners of the country very seriously and take necessary measures for the poor quality of marketed hand sanitizers. materials and methods: attenuated total reflectance-fourier transform infrared spectroscopy (atrftir) was used to determine the concentration of ethanol in five brand hand sanitizers purchased from haramaya, dire dawa, and harar. results: the results of the study showed that the concentration of ethanol in brand 1, brand 2, brand 3, brand 4 and brand 5 was 58.20, 56.51, 55.02, 51.33 and 93.03%, respectively, and was not in good agreement with the label claim marked as ethanol concentration. the hand sanitizer formulated by the department of chemistry, haramaya university was found to contain 77.2% ethanol, which was in acceptable concentration range recommended by the world health organization (who). conclusion: of the six samples of hand sanitizer tested, four of them fail below the who recommended concentration (80%), while one brand had ethanol concentration exceeding the who standard. the determined ethanol concentration of the analyzed hand sanitizers showed a poor correlation with the claimed label except that of hand sanitizer formulated in the haramaya chemistry department laboratory with a significant deviation from the expected values ranging from 16.25% to 35.87%. the poor quality of these hand sanitizers can contribute to the spread of the virus rather than preventing it. therefore, the continued vigilance is required from all stakeholders and authorities to ensure that the product is formulated in accordance with the guidelines recommended by who. keywords: alcohol-based handrubs; attenuated total reflectance-fourier transform infrared spectroscopy; covid-19; ethanol concentration 1. introduction hand sanitizers are one of the key disinfectants being utilized to control the spread of coronavirus disease 2019 (covd-19) (golin et al., 2020). hand sanitizers, also called hand antiseptic or handrub are agents applied to the hands to remove common pathogens (todd et al., 2010). the best way to prevent the spread of infections and decrease the risk of getting sick is by washing our hands with plain soap and water. however, if soap and water are not available for hand washing, center for disease control and prevention (cdc) recommends consumers mailto:yihe300@yahoo.com yiheyis et al. east african journal of sciences volume 16(1): 69–76 70 to use an alcohol-based hand sanitizer that contains at least 60% alcohol (cdc, 2020). hand sanitizers or the alcohol-based handrubs are consumer products in the form of liquid, spray or gel and are thought to generally be effective in killing microorganisms and decreasing infectious agents on hands. the alcohol-based sanitizers are typically the most popular and effective and claims to kill 99.99% of bacteria within seconds including the most resistant form (mithun et al., 2015; tamimi et al., 2015). the principal component and active ingredient of hand sanitizers that are recommended for coronavirus is alcohol at a concentration of at least 60% (v/v). the two formulations recommended by who should comprise either ethanol or isopropyl alcohol. since covid-19 has become a global pandemic, several guidelines have been published by international organizations, such as cdc and who on personal hygiene including, hand washing and hand sanitization (who, 2009; cdc, 2020). this in turn has increased the demand for alcohol-based sanitizers. the demand of hand sanitizers has been steadily increasing in the past 15 months since the outbreak of the covid-19 virus in the globe (berardi et al., 2020), but a sudden spike in demand has been observed in recent months as the rate of infection has surged across the globe. as the virus has begun to spread widely across the world, people have started to “panicbuy” hand sanitizers as a preventive measure. although hand washing with soap and water is strongly recommended for prevention of covid-19, the cdc and who “lists alcohol-based hand sanitizer (with an alcohol content above 60 %) as an alternate for reducing the spread of the virus (cdc, 2020). from the two formulations recommended by who, the covid-19 pandemic has created a considerable demand for alcohol-based hand sanitizers for personal disinfection as well as for disinfection of hard surfaces that the virus can inhabit. this increased demand has pushed many new manufacturers to produce ethanol and isopropyl alcohol based hand-sanitizing products. in ethiopia, in response to the ongoing effort of the country to control the potential outbreak of covid-19, the federal food and drug authority drafted a new temporary directive that gives an exclusive license to manufacturers, enabling them to make hand sanitizer, disinfectant and face masks (efda, 2020). with the covid-19 infection rate surging in ethiopia and the entire world, the sales of hand sanitizers are becoming popular. as a result, numerous generic brands of hand sanitizers have been flooding the market. however, most of the generic brand hand-sanitizers available in ethiopian and the entire world market were not formulated following the who recommended hand rub formulations, and hence, their quality is questionable (berardi et al., 2020; fonseca et al., 2020). therefore, the objective of the study was to investigate the alcoholic content and quality of five different brands of hand sanitizers available in dire-dawa, harar and haramaya markets in eastern ethiopia against the who recommended formulations. 2. materials and methods 2.1. apparatus and instruments a fourier transform infrared (ft-ir) spectrometer (spectrum 65, perkinelmer, waltham, usa) equipped with attenuated total reflectance (atr) accessory was used for acquisition of ftir spectra of the samples. 2.2. chemicals and reagents h2o2 (30%) and glycerol (99%) were purchased from mulu pharmaceuticals (addis ababa, ethiopia). standard ethanol (99.99%) was purchased from carlo-elba (valde-reuil, france). homemade distilled and sterilized water was used throughout the experimental work. 2.3. sample collection and preparation five different brands of commercially available hand sanitizers, each 100 ml (brand 1, brand 2, brand 3, brand 4 and brand 5) were purchased from supermarkets and local pharmacies at haramaya, and harar, and dire dawa towns in july 2020. an ethanol-based hand sanitizer (approximately 78% ethanol) was formulated as per the who recommendation at the department of chemistry, haramaya university for comparison. 2.4. experimental procedure 2.4.1. formulation of ethanol-based hand sanitizer the ethanol-based hand sanitizer (500 ml) containing ethanol 78% (v/v) was formulated as per the who recommended guideline (who, 2009). in detail, 425.5 ml of ethanol (94%), 7.32 ml of glycerol (99%) and 2.08 ml of hydrogen peroxide (30%) were added to polypropylene plastic tank and mixed gently. then, sterilized distilled water (65 ml) was added to bring to final volume (500 ml). the mixture was mixed well and https://bit.ly/2xbnumn https://phenomenex.blog/2020/03/24/sars-cov-2/ https://phenomenex.blog/2020/03/24/sars-cov-2/ https://phenomenex.blog/2020/03/18/washing-your-hands/ https://phenomenex.blog/2020/03/18/washing-your-hands/ yiheyis et al. alcohol content of hand sanitizers in eastern ethiopia 71 the final solution was transferred into suitable containers and quarantined for 72 hours. 2.4.2. physical identification of ethanol in samples the ethanol-based hand sanitizer formulated as per the who guidelines was labeled as hru chem hand sanitizer. the commercial hand sanitizers purchased from supermarkets and local pharmacies were labeled as brand 1, brand 2, brand 3, brand 4, and brand 5. to confirm that the samples contained ethanol, flammability of the purchased samples were compared to that of homemade ethanol-based hand sanitizer (almengor & monaghan, 2015). for the flammability test, equal amounts of each brand of alcohol-based hand sanitizers purchased from the market and the one formulated in hru chem lab were simply dripped on six different crown corks. then, the sanitizers were lit with lighter to test the presence of alcohol in the samples (qualitative test). 2.4.3. determination of ethanol concentration the ethanol concentrations in the samples were determined using the perkinelmer spectrum 65 ft-ir spectrometer equipped with attenuated total reflectance (atr) accessory. the spectral acquisition was made in the range of 4000–600 cm–1 with 4 scans and resolution of 4 cm-1. an external calibration curve drawn from ten standard solutions (0–80%) of ethanol comprising the same quantity of glycerol and hydrogen peroxide (1.45 and 0.125% w/w, respectively) were used to estimate ethanol concentration from the instrument response. 3. results and discussion 3.1. determination of ethanol concentration the ethanol-based hand sanitizer model was created based on the standard calibration curve derived from the area of a peak at 1043 cm–1, which corresponds to the co stretching frequency in a primary alcohol. the ft-ir spectrum containing 80% ethanol in the region 1150-950 cm-1 is shown in figure 1. figure 1. ft-ir spectrum of 80% ethanol. 1120 1080 1040 1000 960 0.00 0.22 0.44 0.66 0.88 1.10 1.32 1.54 1.76 1.98 a b so rb an ce wave number (cm–1) 80% ethanol concentration yiheyis et al. east african journal of sciences volume 16(1): 69–76 72 the ftir spectra of a series of standard ethanol solutions with ethanol levels ranging from 0–80% (blank, 10, 20, 30, 40, 50, 60, 70, and 80%) in the region 1150-950 cm–1 were acquired and given in figure 2. figure 2. ft-ir spectra of different concentration of ethanol ranging from 0–80% in the region 1150-950 cm–1. the area of the peak at 1043 cm–1 was then used to construct a calibration curve using simple beer’s law. the calibration curve exhibits an excellent linearity with a correlation coefficient of 0.9907. the calibration curve was produced using the peak area at 1043 cm–1 and shown in figure 3. figure 3. calibration curve of ethanol % produced using peak area of 1043 cm–1. 1140 1120 1100 1080 1060 1040 1020 1000 980 960 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 10% ethanol 20% ethanol 30% ethanol 40% ethanol 50% ethanol 60% ethanol 70% ethanol 80 % ethanol blank a b so rb an c e wavenumber (cm-1) 0 20 40 60 80 0 2 4 6 8 10 12 14 y = 0.148x + 0.104 r² = 0.9907 p e ak a re a ethanol concentration (%) yiheyis et al. alcohol content of hand sanitizers in eastern ethiopia 73 the calibration curve was then used to determine the concentration of ethanol in five commercial hand sanitizers and hand sanitizer formulated at chemistry department laboratory of haramaya university. the ftir spectra of the samples were acquired and presented in figure 4. the peak area of 1043 cm–1 was obtained and the percentage of ethanol in each samples were determined against the calibration curve. the corresponding ethanol concentration versus label claim of the hand sanitizer products is given in table 1. the percent error between the label claim and the determined concentration of ethanol in each sample was calculated using the following equation (fonseca et al., 2020): percent error = determined concentration of ethanol − label claim concentration of etahnol label claim concentration of ethanol x 100 figure 4. atr-ftir spectra of the six samples of hand sanitizer. table 1. concentration of ethanol in five brands of commercial ethanol-based hand sanitizers and hand sanitizer hru chem. sample mean ± standard deviation label claim ethanol concentration (%) error (%) brand 1 58.20+0.199 80 27.5 brand 2 56.51+0.090 80 29.37 brand 3 55.02+0.192 80 31.25 brand 4 51.33+0.061 80 35.87 brand 5 93.03+0.071 80 16.25 hru chem 77.17+0.061 80 3.62 the determined ethanol concentration of the sample hand sanitizers showed a poor correlation with the claimed label except that of hru chem hand sanitizer with a significant deviation from the expected values ranging from 16.25% to 35.87%. among the commercial samples of hand sanitizers, the highest and the lowest percent deviations from the claimed label of ethanol concentration were observed for brand 4 and brand 5 hand sanitizers, respectively. among the six samples, brand 5 contained a higher percentage of ethanol than the label claim concentration of ethanol (80%) and hru chem hand sanitizer, which is in a good agreement with the expected value. the antimicrobial activity of alcohols is linked to their ability to denature proteins. the best antimicrobial efficacy can be achieved with solution of ethanol (60 to 1140 1120 1100 1080 1060 1040 1020 1000 980 960 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 hru chem brand 1 brand 2 brand 3 brand 4 brand 5 a b so rb an c e wavenumber (cm -1 ) yiheyis et al. east african journal of sciences volume 16(1): 69–76 74 80%) (kampf and kramer, 2004). the higher percentage of ethanol (>80%) is not a guarantee for better antimicrobial efficacy. higher concentrations are less potent/effective because proteins are not denatured easily in the absence of water, which means proteins requires the presence of water to be easily denatured, whereas solutions with a lower than 60% alcohol concentration may only reduce/slow the growth of germs but not kill them. 3.2. physical properties of commercial hand sanitizers the results obtained showed that the five hand sanitizers, brand 1, brand 2, brand 3, brand 4 and brand 5, purchased from the local market were not formulated as per the who recommended hand rub formulations and hence not effective against coronaviruses. this may have negatively affected the nation's efforts to prevent the spread of the virus, and predisposes communities to unnecessary costs. while brand 5 hand sanitizer seemed to have been distributed in the market simply by bottling the ethanol pure as purchased from the sugar factory without any formulation. 3.2.1. flammability test all the five samples and hru chem hand sanitizer were ignited at a rapid rate. this test indicated that all samples contained ethanol. 3.2.2. evaporation rate test each of the six hand sanitizers was spritzed on palms separately and rubbed over the hand surface. the four generic brand sanitizers named brand 1, brand 2, brand 3 and brand 4 evaporate/dried slowly within 32 seconds while brand 5 dried very quickly within 8 seconds and the hru chem hand sanitizer dried within 13 seconds. this indicate that brand 1, brand 2, brand 3 and brand 4 generic hand sanitizers purchased from the local market contained low levels of the active ingredient (ethanol) compared to brand 5 and hru chem hand sanitizers. 4. conclusion and recommendation in this study, ethanol concentrations of five generic brand hand sanitizers available in eastern ethiopian markets were analyzed using atr-ftir. the results showed that the commercially available hand sanitizers were not formulated as per the who recommended hand rub formulations and their quality is low (in terms of ethanol concentration). this would negatively affect ethiopia’s efforts to prevent the spread of the coronavirus in the country. based on the experimental results, the researchers recommend that the food and drug authority of ethiopia needs to inspect and check the quality of hand sanitizers marketed in all corner of the country very frequently and take the necessary measures to maintain the required quality and effectiveness of marketed hand sanitizers in controlling covid-19 and other contagious respiratory diseases 5. acknowledgments thanks are due to the office of the vice-president for research affairs of haramaya university (hucf-202006-na-01) for funding the research. 6. references almengor, s., and monaghan, w. p. 2015. up in flames: a flammability assessment of alcohol-based hand sanitizers on common perioperative materials. international journal of advanced nursing studies, 4(1): 13. berardi, a., cenci-goga, b., grispoldi, l., cossignani, l., and perinelli, d.r. 2020. analysis of commercial hand sanitisers amid covid-19: are we getting the products that we need? aaps pharmscitech, 21(7): 1–6. berardi, a., perinelli, d.r., merchant, h.a., bisharat, l., basheti, i.a., et al. f. 2020. hand sanitisers amid covid-19: a critical review of alcohol-based products on the market and formulation approaches to respond to increasing demand. international journal of pharmaceutics, 584: 119431. doi: 10.1016/j.ijpharm.2020.119431. cdc (center for disease control). 2020. coronavirus disease 2019 (covid-19): how to protect yourself and others. centers for disease control and prevention. https://www.cdc.gov/coronavirus/2019ncov/prevent-getting-sick/prevention.html. accessed on july 25, 2020. efda (ethiopian food and drug authority). 2020. temporary covid-19 medical product approval and import permit authorization directive. http://efmhaca.hcmisonline.org/wpcontent/uploads/2020/04/temporarycovid-19-medical-product-approval-andhttps://doi.org/10.1016/j.ijpharm.2020.119431 yiheyis et al. alcohol content of hand sanitizers in eastern ethiopia 75 import-permit-authorization-directive.pdf. accessed on april 2020. fonseca, f.s., brito, l.r., pimentel, m.f. and leal, l.b. 2020. determination of ethanol in gel hand sanitizers using mid and near infrared spectroscopy. journal of the brazilian chemical society, 31: 1759–1763. golin, a.p., choi, d. and ghahary, a. 2020. hand sanitizers: a review of ingredients, mechanisms of action, modes of delivery, and efficacy against coronaviruses. american journal of infection control, 48(9): 1062–1067. kampf, g.n. and kramer, a. 2004. epidemiologic background of hand hygiene and evaluation of the most important agents for scrubs and rubs. clinical microbiology reviews, 17(4): 863–893. mithun, a., udugade, b., manoj, b. and pawade, d. 2015. formulation and evaluation of novel herbal hand sanitizer. indo american journal of pharmaceutical research, 5(01): 483–487. tamimi, a., maxwell, s., edmonds, s. and gerba, c. 2015. impact of the use of an alcohol-based hand sanitizer in the home on reduction in probability of infection by respiratory and enteric viruses– erratum. epidemiology and infection, 143(15): 3342–3342. todd, e.c., michaels, b.s., holah, j., smith, d., greig, j.d. and bartleson, c.a. 2010. outbreaks where food workers have been implicated in the spread of foodborne disease. part 10. alcohol-based antiseptics for hand disinfection and a comparison of their effectiveness with soaps. journal of food protection, 73(11): 2128–2140. who (world health organization). 2009. who guidelines on hand hygiene in health care: first global patient safety challenge clean care is safer care. who-recommended handrub formulations. https://www.ncbi.nlm.nih.gov/books/nbk144 054/. accessed on march 25, 2020. https://www.ncbi.nlm.nih.gov/books/nbk144054/ https://www.ncbi.nlm.nih.gov/books/nbk144054/ yiheyis et al. east african journal of sciences volume 16(1): 69–76 76 ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(1): 93–100 licensed under a creative commons *corresponding author: desta.ab12@gmail.com attribution-noncommercial 4.0 international license. registration of ‘pawe-2’ rice variety for upland ecosystem in ethiopia desta abebe1*, mulugeta atnaf2, gedifew gebrie1, abebaw dessie2, desalegn wondifraw1, mulugeta bitew4, atsedemariyam tewachew2, yeshiwas sendekie1, desalegn teshale1 tesfaye gudisa1, and zeynu tahir3 1pawe agricultural research center, p.o. box25, pawe, ethiopia 2fogera national rice research and training center, p.o. box 190, wereta, ethiopia 3gondar agricultural research center, p.o. box 1337, gondar, ethiopia 4debre markos agricultural research center, p.o. box 357, debre markos, ethiopia abstract background: rice (oryza sativa l.) is produced in ethiopia. however, the national average yield is far below the potential of the crop due to, among others, limited availability of stable, high yielding and disease tolerant upland rice varieties. this problem has seriously limited production of the crop in the country. objective: the research was conducted to evaluate and release a stable high yielding and disease resistant/tolerant upland rice varieties for the typical upland rice ecosystems in ethiopia. material and methods: the rice variety (currently named pawe-2) introduced from brazil in 2012 was evaluated along with nerica-4 and fogera-1 as local and standard check varieties, respectively, at pawe and metema (typical upland rice ecosystems) beginning from a 2013. after the evaluation of the variety for six years, verification trials were conducted in 2019 and in 2020. results: pawe-2 had better performances for most agronomic traits than the check varieties. the newly released variety, ‘pawe-2’ had an average grain yield of 5058.93 kg ha–1, and it had yield advantages of 15.68% and 13.52% over fogera-1 and nerica-4 rice varieties, respectively, as shown by the results of the verification trails conducted in 2019. moreover, pawe-2 had a higher biomass yield, larger grain size, white caryopsis color, early maturity and resistance to diseases and pests than the check varieties. conclusions: it is concluded that the variety ‘pawe-2’ is superior to the other varieties in terms of yield, yield stability, and resistance to pests and diseases. therefore, the national variety release committee approved pawe-2 for cultivation in the mid altitude (750–1800 meters above sea level) and similar typical upland rice ecosystems in ethiopia. keywords: early maturing; grain yield; upland rice variety; verification and yield advantage 1. introduction rice (oryza sativa l.) is a cereal commonly used as a staple food crop for a significant part of human population. it provides 27% of the calories in the world’s low and middle-income countries (fukagawa and ziska, 2019). the rice production system is classified into lowland and upland rice. in lowland rice, fields are usually flooded during part or all of the growing season; lowland rice includes rain-fed lowland, irrigated lowland, deep-water and mangrove swamp (saito et al., 2013). upland rice grows on level or sloping, unbunded fields and flooding is rare in this system. in some cases, especially in latin america, supplemental irrigation may be used. upland rice is grown under crop rotation systems with other crops, or under slash-and-burn systems (atlin et al., 2006; pinheiro et al., 2006; saito et al., 2006). recent statistics from 71 countries from asia, latin america, and subsaharan africa show that lowland and upland rice account mailto:desta.ab12@gmail.com desta et al. east african journal of sciences volume 16(1): 93–100 94 for 92 and 8% of total rice cultivation area, respectively (saito et al., 2018). rice is one of the most strategic crops in africa, and particularly in ethiopia (meron abebe, 2016). ethiopia has immense potential for growing rice. in 2019/20 meher season, 178,185 households produced rice on 57,575.72 hectares of land and produced a total of 170, 630.1 tons with average yield of 2.964 t ha–1. the total area cultivated for rice has reduced by 9.13%, but the total yield has reduced only by 0.71% and the national average yield has increased by 0.252 ton (9.29%) than 2018/19 main production season (csa, 2020). the increase of average national yield with a one-season change seems showing the productivity of the crop is fast growing, but it is still low as compared to its potential. this is due to biotic and abiotic stress including limited number of varieties available to withstand major biotic and abiotic stress. in this regard, pawe and metema agricultural research centers have been working on the development of upland rice varieties with high yield potential, early maturity and resistance to major rice diseases (blast, brown spot, sheath blight, bacterial panicle blight and sheath spot) and pests (taye tadesse et al., 2019). evaluation of introduced rice varieties and available genotypes over locations and seasons is one the breeding methods to develop high yielding upland rice varieties in ethiopia. accordingly, the introduced variety from brazil in 2012 was evaluated along with the existing rice varieties over locations and seasons to test the cultivation value of the variety in ethiopia. the introduced variety was found to be superior to the existing rice varieties for yield and other desirable agronomic traits and approved for cultivation by the national variety release committee in 2020 named as pawe-2 upland rice variety. this paper presents the overall performances of the recently released upland rice variety (pawe-2) aiming at providing information for all actors in rice production in ethiopia. evaluation of introduced rice varieties and available genotypes over locations and seasons is one the breeding methods to develop high yielding upland rice varieties in ethiopia. accordingly, the introduced variety from brazil in 2012 along with the existing rice varieties was evaluated over locations and seasons to test its cultivation value in ethiopia. the introduced variety was found to be superior over the existing rice varieties for yield and other desirable agronomic traits and approved for cultivation by the national variety release committee in 2020 named as pawe-2 upland rice variety. this paper presents the overall performances of the recently released upland rice variety (pawe-2) aiming to provide information for all actors involved in rice production in the country. 2. varietal evaluation three varieties having unique characters like high grain yield, long grain size, early maturity, and disease and pest resistance were introduced from brazil in 2012. the varieties are commercially cultivated in brazil. the three introduced varieties and two standard check varieties, nerica-3 and nerica-4 were evaluated during 2013 to 2015 main cropping seasons in northwestern ethiopia specifically at parc (pawe agricultural research center). during a preliminary yield evaluation trial, parc.dat.v-3.2013 was identified as a candidate variety (pawe-2) since it outperformed the standard check varieties and other two introduced varieties. the candidate variety and other genotypes, a total of 17 genotypes were advanced to national variety trial and evaluated across locations for two years. the standard check was nerica-4 released in 2006 in ethiopia. the genotypes were evaluated at major upland rice growing areas, namely, fogera (woreta), gondar (metema), pawe, assosa (kamashi), and shire (mai-tsebri) for two years (2016/2017 to 2017/2018) in a randomized complete block design (rcbd) with three replications. in 2018/2019 cropping season, parc.dat.v-1.2013 as candidate variety-1 and parc.dat.v-3.2013 as candidate variety-2 (pawe-2) along with nerica-4 and fogera-1 as local and standard check varieties, respectively, were evaluated for verification at seven test sites. the national variety release committee evaluated the varieties on the field. pawe-2 consistently outyielded the other tested rice varieties over three years. the average yield of pawe-2 was 5033.01kg ha–1 in 2013 up to 2015 main cropping seasons (table 1). combined years over locations analysis revealed that pawe-2 produced an average yield of 4984.50 kg ha–1 during 2016–2017 cropping season (table 3). pawe-2 also showed superior overall agronomic performances over the standard check (fogera-1) and the local check (nerica-4) varieties under verification trial. likewise, it proved to be more resistant for leaf blast, panicle blast, and brown spot; and scored less damage by different insects like termite and stalk eye fly than the check varieties. the results of the over locations and seasons revealed that, pawe-2 was superior in grain yield performance, protein content, and diseases resistance. thus, the recommendation of pawe-2 for cultivation was reasonable and it is important to register as a commercial desta et al. registration of ‘pawe-2’ rice variety ethiopia 95 variety to promote its production in typical upland rice ecosystems. in the same manner, girma mengistu et al. (2013) were evaluated the pipeline upland rice genotypes against the standard check viz., superica-1, across six environments during the 2012 main cropping seasons and the variety “chewaka” showed superior performance over the other pipelines and recommended by the national variety released committee to be registered as a variety. similarly, famoso et al. (2019) reported the registration of ‘pvl01’ rice as evaluated the rice genotypes across seven environments for resistance to provisia herbicide, containing the active ingredient quizalofop, an aacase (group 1) herbicide. 3. agronomic and morphological characters pawe-2 showed a higher number of tillers per plant, a larger number of field grain per panicle, larger-sized seeds, higher grain yield and better resistance to diseases and pests than the standard check (fogera-1) during the variety verification trial. pawe-2 is distinguished by a white seed color and long seed size, and thousand-grain weight of 12.34 grams. it attained 50% heading, 50% heading, 50% flowering, and 85% maturity in 80, 84 and 118 days, respectively, after emergence. it had panicle length of 21.09 cm and plant height of 97.51 cm (tables 4 and 5) with the average number of fertile tillers per plant of 6.4. harrell et al. (2021) reported the registration of different rice varieties following similar research methods and the rice varieties registered had a higher number of tillers per plant, a larger number of field grain per panicle, largersized seeds, a higher grain yield and better resistance to different rice diseases. 4. yield performance pawe-2 was produced a higher average mean grain yield (5033.01 kg ha–1) than nerica-4 (4405.02 kg ha–1) and nerica-3 (4305 kg ha–1) during the three years (2013– 2015) evaluation (table 1). pawe-2 had a higher yield advantage of 14.26% and 16.89% over nerica-4 and nerica-3 varieties, respectively. it also produced a higher grain yield than the standard check (fogera-1) and local check (nerica-4) during the variety verification trial in 2018/2019 main cropping season at seven sites (table 4). pawe-2 variety had a higher biological yield (55414.29 kg ha–1) than the two check varieties fogera-1 (44214.29 kg ha-1) and nerica-4 (43996.67kg ha–1) (table 4). consistent with these results, harrell et al. (2021) reported the registration of different rice varieties that had higher yield advantages than the standard and the local checks as tested in more year and seasons. 5. reaction to pest and disease pawe-2 was superior in tolerance to diseases (leaf blast, panicle blast and brown spot) and sustained less termite and shoot fly damage compared to the check varieties (fogera-1 and nerica-4). significantly lower termite damage of 21% was recorded to pawe-2 than the fogera1 (43%) and nerica-4(50%) check varieties (tables 2 and 4), and in 2018/2019 cropping season, the four genotypes did not show any symptoms of the disease. consistent with this result, harrell et al. (2021) reported similar findings. rice leaf blast (magnaporthe grisea) is a key concern in combating global food security given the disease is responsible for approximately 30% of rice production losses globally-the equivalent of feeding 60 million people (nalley et al., 2016). these losses increase the global rice price and reduce consumer welfare and food security. even, rice brown spot (helminthosporium oryzae) is a chronic disease that affects millions of hectares of rice every growing season, grown by some of the most resource-poor farmers. brown spot is conventionally perceived as a secondary problem that affects rice crops that experience physiological stresses, e.g., drought and poor soil fertility, rather than a true infectious disease (barnwal et al., 2013). therefore, bs is by far one the strongest yield reducers amongst rice diseases today. the range of reported yield losses to bs, often expressed in relative terms, is variable from 26 to 52% (chakrabarti, 2001). desta et al. east african journal of sciences volume 16(1): 93–100 96 table 1. combined mean grain yield and other agronomic traits for upland rice genotypes in pawe at two locations over three years (2013–2015). s/n variety dh dm ph (cm) pl (cm) ftp fgp gy (kg ha–1) tsw(g) 1 parc dat-v1-2013 78.21 113.11 90.54 22.16 9.52 145.58 4838.16 26.15 2 parc dat-v2-2013 81.5 111.15 91.50 23.26 8.51 139.65 4715.56 26.01 3 parc dat-v-3-2013 82.5 114.20 87.08 23.05 8.05 143.48 5033.01 25.90 4 nerica-3 73.5 112.5 82.5 21.25 7.15 135.8 4305.5 24.8 5 nerica-4 (check) 71.23 109.00 84.30 21.15 8.45 137.78 4405.02 25.00 mean 77.388 111.992 87.184 22.174 8.336 140.458 4659.45 25.572 maximum 82.5 114.2 91.5 23.26 9.52 145.58 5033.01 26.15 minimum 71.23 109 82.5 21.15 7.15 135.8 4305.5 24.8 note: dh = days to 50% heading; dm = days to 85% maturity; pl = panicle length (cm); ph = plant height (cm); ftp = fertile tillers/plant; fgp = filled grains/panicle; gy = grain yield (kg ha–1); and tsw (g) = thousand seed weight. table 2. mean values of different diseases reaction scores (0–9) of the genotypes in pawe at two locations over three years (2013–2015). s/n variety leaf rust panicle blast brown spot sheath rot termite damage (%) seedling tillering dough maturity tillering milk stage 1 parc dat-v1-2013 0 0 1 0 0 0 0 2.0 2 parc dat-v2-2013 0 0 0 0 1 0 1 1.6 3 parc dat-v-3-2013 0 0 0 1 0 0 0 1.5 4 nerica-3 1 1 0 0 1 1 0 4.5 5 nerica-4 (check) 1 0 0 0 0 0 0 3.5 note: 0 = highly resistant and 1 = resistance reactions. desta et al. registration of ‘pawe-2’ rice variety ethiopia 97 table 3. combined mean grain yield and other yield related parameters of 17 upland rice genotypes during 2016-2017cropping season. s/n genotypes (g) code dh dm ph pl ftp fgp gy (kg ha–1) 1 nm1-29-4-b-p-80-8 g1 73 101 93.04 21.38 5.85 130.14 4845.50 2 art16-9-29-12-1-1-2-b-1-1 g2 73 101 102.77 20.91 6.78 120.79 3965.60 3 art16-9-14-16-2-2-1-b-1-2 g3 69 98 93.96 22.24 5.98 117.46 4745.80 4 art16-9-33-2-1-1-1-b-1-2 g4 77 104 98.87 21.13 6.23 127.92 4834.30 5 art16-9-122-33-2-1-1-b-1-1 g5 75 102 97.90 20.73 6.74 117.33 4885.80 6 art15-19-5-4-1-1-1-b-1-1 g6 75 102 96.28 21.34 6.10 110.43 4658.00 7 art16-5-9-22-2-1-1-b-1-2 g7 76 102 95.27 19.99 6.20 126.85 5027.20 8 art16-21-4-7-2-2-2-b-2-2 g8 73 101 94.46 20.95 6.14 125.79 4717.90 9 art16-9-16-21-1-2-1-b-1-1 g9 76 101 102.07 21.64 5.87 114.26 4902.50 10 art15-13-2-2-2-1-1-b-1-2 g10 73 99 92.54 21.61 6.49 114.47 3762.10 11 art15-16-45-1-b-1-1-b-1-2 g11 74 101 96.56 21.53 5.86 189.89 4398.60 12 art16-5-10-2-3-b-1-b-1-1 g12 75 101 102.30 21.98 6.19 122.80 4603.20 13 art16-4-1-21-2-b-2-b-1-2 g13 76 103 97.12 21.23 6.19 130.41 4516.80 14 parc.dat.v-1.2013 g14 78 104 97.64 21.37 7.12 131.74 4528.00 15 parc.dat.v-2.2013 g15 79 104 99.68 22.14 7.00 125.19 4207.40 16 parc.dat.v-3.2013 g16 79 106 99.29 21.92 6.02 129.73 4984.50 17 nerica-4(check) g17 72 101 93.09 20.56 6.99 124.67 4712.70 mean 74.80 101.85 97.26 21.32 6.36 126.42 4617.88 cv (%) 3.76 2.19 7.93 7.92 23.63 27.21 16.67 lsd (5%) 1.97 1.57 5.41 1.18 1.05 24.12 539.91 genotype (g) *** *** *** ** ns ns *** environment (e) *** *** *** *** *** *** *** genotype x environment (g x e) ns ns ns ns ns ns ** note: dh = days to 50% heading; dm = days to 85% heading; pl = panicle length (cm); ph = plant height (cm); ftp = number of fertile tillers per plant; fgp = number of filled grains per panicle; and gy = grain yield (kg ha–1). ** and *** refer to significant level at p < 0.01 and 0.001, respectively, and ns = not significant at p < 0.05. desta et al. east african journal of sciences volume 16(1): 93–100 98 table 4. mean grain yield, other agronomic traits and diseases reaction of parc.dat.v-1.2013 (candidate-1), parc.dat.v-3.2013, pawe-2 (candidate-2) and the check varieties during multi-location evaluation in 2019/2020. traits candidate-1 candidate-2 nerica-4 fogera-1 days to 50% heading 81.57 80.43 71.86 72.00 days to 50% flowering 85.43 84.14 75.14 75.14 days to 85% maturity 121.57 117.86 106.14 105.00 plant height (cm) 94.84 97.51 87.00 89.66 panicle length (cm) 20.31 21.09 19.66 19.57 number of fertile tillers/plants 6.03 6.40 4.83 4.71 number of unfertile tillers/plants 0.06 0.11 0.20 0.14 number of filled grain/panicles 147.53 152.17 137.06 140.8 number of unfilled grain/panicles 4.60 4.59 4.11 3.91 grain yield (kg ha–1) 4727.50 5058.93 4456.24 4372.9 1000 seed weight 12.07 12.34 11.36 11.53 moisture content 27.79 28.04 26.79 26.86 stand count 670571.43 731714.29 600857.14 624857.14 biological yield (kg ha–1) 51885.71 55414.29 43996.67 44214.29 termite damage (%) 0.21 0.21 0.50 0.43 leaf blast at seedling 0.00 0.00 0.00 0.00 leaf blast at tillering 0.00 0.00 0.00 0.00 panicle blast at dough stage 0.00 0.00 0.00 0.00 panicle blast at maturity stage 0.00 0.00 0.00 0.00 brown spot at tillering 0.00 0.00 0.00 0.00 brown spot at milk stage 0.00 0.00 0.00 0.00 sheath rot 0.00 0.00 0.00 0.00 table 5. morpho-agronomic characteristics of pawe-2 upland rice variety. variable description variety name: pawe-2 agronomic and morphological characteristics: adaptation area pawe, fogera, assosa, gondar, maitsebri and other similar agroecologies of ethiopia. • altitude (m.a.s.l.) a 750–1860 • rainfall (mm) 1100–1457 seed rate (kg ha–1) 60 planting date mid-june to early july depending on the onset of rainfall spacing(cm) 25 cm between rows for row drill planting fertilizer rate (kg ha–1) and time of application n = 69 (1/3 at planting, 1/3 at tillering and 1/3 at panicle initiation) and p2o5 = 23 (all at planting) days to heading 80 days to maturity 118 panicle length(cm) 21.1 plant height(cm) 97.5 thresh ability easy lodging incidence none shattering moderately resistant seed size(mm) slender shape [length (9.2): width (2.5) =7.14] growth habit erect no. of grains per panicle 152 1000 seed weight (g) 12.34 caryopsis color white crop pest reaction resistant to major rice diseases grain yield (kg ha–1) research field 5059 farmers field 4847 year of release 2020 breeder/maintainer: pawe agricultural research center /eiar note: a m.a.s.l. = meters above sea level. desta et al. registration of ‘pawe-2’ rice variety ethiopia 99 6. other quality traits in the major rice-consuming countries, grain quality characteristics dictate the market value of the commodity and play an important role in the development and adoption of new varieties. grain quality includes such traits as physical appearance and nutritional values. the rice varieties were mainly developed based on yield and other desirable traits. however, pawe-2 contains has also good nutritional values like protein, fat and ash, and better market-oriented variety than the tested genotypes. the average kernel length of the variety was higher than other tested varieties with a higher protein content (4.79%) (atsedemariyam tewachew et al., 2018). 7. conclusion the results of this study have demonstrated that pawe-2 is a high yielding variety, resistant to major rice diseases such as blast and brown spot. moreover, the variety has a greater number of tillers per plant, a greater number of filled grains per plant, longer grains and white caryopsis color. its grain is also relatively rich in protein, ash and fat. generally, the variety has traits preferred by farmers as confirmed by their positive feedback during the evaluation and verification trials. hence, it is necessary to promote the variety in typical upland rice growing areas of ethiopia. 8. acknowledgements the authors thank the ethiopian institute of agricultural research for providing financial supports to evaluate and release the variety and fogera national rice research and training centre for cooperating and coordinating the evaluation trials across locations. the authors also appreciate the technical staff of rice improvement program of pawe, fogera, gondar-metema research centers for smooth implementation of the trials over the years. 9. references atlin, g.n., lafitte, h.r., tao, d., laza, m., amante, m. and courtois, b. 2006. developing rice cultivars for high-fertility upland systems in the asian tropics. field crops research, 97(1): 43–52. atsedemariyam tewachew, wassu mohammed and alemayehu assefa. 2018. genetic variability, heritability and genetic advance analysis in upland rice (oryza sativa l.) genotypes for yield and yield related traits in benishangul gumuz, ethiopia. international journal of plant breeding and crop science, 5(3): 437–443. barnwal, m., kotasthane, a., magculia, n., mukherjee, p., savary, s., et al. 2013. a review on crop losses, epidemiology and disease management of rice brown spot to identify research priorities and knowledge gap. european journal of plant pathology, 136: 443–457. csa (central statistical agency). 2020. agricultural sample survey 2019/20. statistical report, the federal democratic republic of ethiopian central statistical agency, addis ababa, ethiopia. famoso, a.n., harrell, d.l., groth, d.e., webster, e.p., oard, j.h., et al. 2019. registration of ‘pvl01’ rice. journal of crop registrations, 13(3): 330–333. doi:10.3198/jpr2019.01.0002crc. faostat (food and agriculture organization corporate statistical database). 2017. statistical database. food and agriculture organizations of the united nations. fukagawa, n.k. and ziska, l.h. 2019. rice: importance for global nutrition. journal of nutritional science vitaminology, supplement, 65: s2–s3. doi https://doi.org/10.3177/jnsv.65.s2. girma mengistu, dagnachew lule, kebede desalegn, hailu feyisa, geleta gerema and kasa mamo. 2013. registration of “chewaka” upland rice variety. east african journal of sciences, 7(1): 59–60. grisp (global rice science partnership). 2013. rice almanac, rice almanac. available at https://doi.org/10.1093/aob/mcg189. harrell, d.l., brown, s.a., famoso, a.n., fontenot, k.a., groth, d.e., et al. 2021. rice varieties and management tips. pp. 1–31. available at lsu agcenter’sricewebsiteatwww.lsuagcenter.com /en/crops_livestock/crops/rice/publication-s. meron abebe. 2016. the contributions and challenges of rice value chain development on the livelihood of small holder rice. m.a. theis, addis ababa university, addis ababa, ethiopia. pp. 134. nalley, l., tsiboe, f., durand-morat, a., shew, a. and thoma, g. 2016. economic and environmental impact of rice blast pathogen (magnaporthe oryzae) alleviation in the united states. plos one, 11(12): e0167295.doi: 10.1371/journal.pone.0167295. https://acsess.onlinelibrary.wiley.com/action/dosearch?contribauthorstored=famoso%2c+adam+n https://acsess.onlinelibrary.wiley.com/action/dosearch?contribauthorstored=harrell%2c+dustin+l https://acsess.onlinelibrary.wiley.com/action/dosearch?contribauthorstored=groth%2c+donald+e https://acsess.onlinelibrary.wiley.com/action/dosearch?contribauthorstored=webster%2c+eric+p https://acsess.onlinelibrary.wiley.com/action/dosearch?contribauthorstored=oard%2c+james+h http://dx.doi.org/10.3198/jpr2019.01.0002crc desta et al. east african journal of sciences volume 16(1): 93–100 100 pinheiro, b.da.s., de castro, e.da.m. and guimaraes, c.m. 2006. sustainability and profitability of aerobic rice production in brazil. field crops research, 97(1): 34– 42. https://doi.org/10.1016/j.fcr.2005.08.013. saito, k., linquist, b., keobualapha, b., phanthaboon, k., shiraiwa, t. and horie, t. 2006. cropping intensity and rainfall effects on upland rice yields in northern laos. plant soil, 284: 175–185. https://doi.org/10.1007/s11104-006-0049-5. saito, k., nelson, a., zwart, s.j., niang, a., sow, a., et al. 2013. towards a better understanding of biophysical determinants of yield gaps and the potential for expansion of the rice area in africa. pp. 188–203. in: wopereis, m.c.c., johnson, d.e., ahmadi, n., tollens, e. and jalloh, a. (eds.). realizing africa’s rice promise. doi:10.1079/9781845938123.0188 saito, k., asai, h., zhao, d., laborte, a.g. and grenier, c. 2018. progress in varietal improvement for increasing upland rice productivity in the tropics. plant production science, 21(3): 145–158. doi: 10.1080/1343943x.2018.1459751. taye tadesse, mulugeta atnaf, dawit alemu, tilahun tadesse and shiratori, k., editors. 2019. advances in rice research and development in ethiopia. ethiopian institute of agricultural research, addis ababa, ethiopia. pp. 18. http://dx.doi.org/10.1079/9781845938123.0188 ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(1): 47–56 licensed under a creative commons *corresponding author: germame2004@gmail.com attribution-noncommercial 4.0 international license. genotype x environment interaction and grain yield stability analysis of rice (oryza sativa l.) girma mengistu1*, dagnachew lule1, geleta gerema2, and kebede desalegn2 1oromia agricultural research institute, p.o. box 81265, addis ababa, ethiopia 2cereal research team, bako agricultural research center, p.o. box 3, west shoa, ethiopia abstract background: upland rice has been introduced in to ethiopia recently and widely produced in different parts of the country particularly after it was adopted as the "millennium crop" in 2000. however, limited availability of improved varieties hampers production of the crop. objective: to determine the nature and magnitude of genotype x environment interaction and to identify stable high yielding, blast, and brown spot diseases tolerant varieties for upland rice-growing environments. materials and methods: the experiment was conducted at gutin and bako (2010−2011) and boneya and chewaka districts in the 2011 main cropping seasons. eleven rice genotypes [wab272-b-b-8-h1, yin lu20, irga370-38-1-1-f-b1-1, cnax3031-15-2-1-1, wab502-8-5-1, wabc165(iac165), wab45011-11p31-hb, wab376-b-10-h3 and wab368-b-1-h2-hb] including standard checks (irat 355 and superica 1) were laid out in a randomized complete block design with three replications. grain yield data were collected and analyzed. results: the results showed significant variations among the genotypes in grain yield. the mean grain yield obtained over four environments ranged from 2.36 tons ha–1 (irat 355) to 4.23 tons ha–1 for chewaka variety (yin lu20) and superica-1 produced 2.54 tons ha–1. regression analysis based on eberhart and russell model showed that chewaka variety and wabc165 (iac165) had mean grain yield that were higher than the average for all genotypes. regression coefficient (bi) did not differ significantly from unity and the squared deviations (s2di) approached zero. on the other hand, irga370-38-1-1-f-b1-1, wab450-1111p31-hb and wab376-b-10-h3 had regression coefficient (bi) differ significantly from unity showing that these genotypes are sensitive to different environmental conditions and tend to give higher yield at favorable environments. conclusion: among the tested genotypes, yin lu20 and cnax3031-15-2-1-1 were stable and high yielding and proposed as candidate varieties. in addition, genotype yin lu20 was preferred by farmers for its stability, high seed yield and resistance to rice blast and brown spot diseases and released for cultivation in western ethiopia and other areas in the country with similar agro-ecology, named as chewaka variety. keywords: ammi; genotype; grain yield; regression coefficient; stability; upland rice 1. introduction rice (oryza sativa l.) is an important cereal crop grown for its diverse uses in asia, africa, and australia (dogara and jumare, 2014). the crop ranked third most important cereal crop in the world next to maize (zea mays l.) and wheat (triticum aestivum l.) based on the total grain production (fao, 2017). it is staple food for more than half of the world’s population (muthayya et al., 2014). the rapid increase of the world population also dictates to produce greater quantities of cereal crops such as rice, wheat and maize (kang and priyadarshan, 2007). rice is recently (in 1970s) introduced crop to ethiopia and now mailto:germame2004@gmail.com girma et al. east african journal of sciences volume 16(1): 47–56 48 it has been grown in different parts of the country (tariku et al., 2013, moard, 2010). it ranks second after maize in terms of productivity among other cereal crops, which play a significant role for food security in ethiopia. the national average productivity of rice 2.8 tons ha–1 and it is very low as compared to global mean productivity of 4.4 tons ha-1 (dessie et al., 2018). rice production and productivity is affected by various factors such as lack of improved varieties, diseases, pre and postharvest machineries (moard, 2010). nowadays, the crop has received attention from farmers and investors due to its suitability to make into pancake ethiopian bread locally called ‘injera’. among suitable areas to grow upland rice, western part of oromia, which has suitable climatic and soil conditions. breeders evaluate different genotypes in order to identify high yielding, widely adaptable and stable over the testing environments. genotypes exhibiting fluctuating yield when grown in different environments or agro-climatic zones complicate demonstrating the superiority of a particular variety. multi-environment yield trials are crucial to identify adaptable high yielding cultivars and discover sites that best represent the target environment. the performance of a genotype is dependent on the genetic capacity of the variety, the environment where the variety is grown, and the interaction between the genotype and the environment (yan, 2001; yan and hunt, 2001). genotypes x environment interactions occur when the responses of two genotypes to different levels of environmental factors fail to be parallel (allard and bradshaw, 1964). the regression model proposed by eberhart and russell (1966) allows for the computation of a complete analysis of variance with individual stability estimates and departure from linearity of a regression line. the model considers a stable variety as the one with a high mean yield, bi=1 and s2di = 0. similarly, genotypes with a high s2di deviate significantly from linearity and have a less predictable response for the given environments (eberhart and russell, 1966). additive main effects and multiplication interaction (ammi) model, involves correlation or regression analysis that also relates the genotypic and environmental score derived from a principal component analysis of the genotype x environment interaction matrix to genotypic and environmental covariates (zobel et al., 1988). upland rice has been introduced recently to ethiopia, now it is widely produced in different parts of the country including western oromia. however, limited availability of improved varieties hampers production of the crop. rice genotypes were evaluated and developed in the northern parts of the country (lakew et al., 2017; lakew et al., 2014; tariku et al., 2013; zewdu et al., 2020). however, no study was conducted on stability of rice genotypes in western oromia. therefore, this study was done to determine the nature and magnitude of genotype x environment interaction and identify superior and stable upland rice genotypes for the test environments and similar agro-ecologies. 2. materials and methods 2.1. description of the study areas the study was conducted at gutin [1200–1799 meter above sea level (m.a.s.l.)] and bako (1650 m.a.s.l) during the 2010 and 2011 cropping seasons, and boyena (1300 m.a.s.l) and chewaka (900 to 1400 m.a.s.l) in the 2011 main cropping season. the study was executed under rainfed upland conditions. 2.2. experimental materials, design and procedures eleven rice genotypes including standard checks (irat 355 and superica 1) were used in the study (table 1). at all locations, the experiment was laid out as a randomized complete block design with three replications. seeds of each genotype were sown in six rows of 5 m long with 0.2 m spacing between rows and 1 m between blocks. a seed rate of 80 kg ha−1 was used. fertilizer rate of 100 kg dap ha–1 (46 kg p2o5 ha–1) and 50 kg urea ha–1 (23 kg n ha–1) were used. all rate of the dap fertilizer was applied at planting; however, urea was applied in split twice, i.e., ½ at planting and the other ½ at knee height (panicle initiation) growth stage of the crop. management practices were done according to recommendations. plants in the four middle rows were harvested and grain yield was adjusted at 12% seed moisture content before weighing and data processing for analysis. girma et al. genotype x environment interaction and yield stability in rice 49 table 1. rice genotypes used in the study. s/n genotype name origin 1 wab272-b-b-8-h1 africarice 2 yin lu20 irri 3 irga370-38-1-1-f-b1-1 irri 4 cnax3031-15-2-1-1 unknown 5 wab502-8-5-1 africarice 6 wabc165(iac165) africarice 7 wab450-11-11p31-hb africarice 8 wab376-b-10-h3 africarice 9 wab368-b-1-h2-hb africarice 10 irat-335 standard check 11 superica-1 standard check 2.3. data analysis the combined data across locations and years were used to compute analysis of variance (anova) using r (2016) statistical software. the responses of the genotypes were evaluated based regression coefficients (eberhart and russel, 1966) and additive main-effect and multiplicative interaction (ammi) models in agrobase software (agrobase, 2000). a linear model proposed by eberhart and russell (1966) is: yij = i +biij +s2dij where, yij is the mean performance of ith variety (i = 1, 2, …, n) environment; i is the mean of ith variety over all the environments; bi is the regression coefficient which measures the response of ith variety to varying environments; s2dij is the deviation from regression of ith variety in the jth environment; and ij is the environmental index of jth environment. ammi model (gauch and zobel, 1996): 𝛶𝑔𝑒𝑟 = 𝜇 + 𝛼𝑔 + 𝛽𝑒 + ∑𝑛𝜆𝑛𝛾𝑔𝑛𝛿𝑒𝑛 + 𝜌𝑔𝑒 + 𝑔𝑒𝑟 where, yger is the observed yield of genotype g in environment e for replication r; additive parameters:  the grand mean; 𝛼𝑔the deviation of genotype g from the grand mean; and 𝛽𝑒 the deviation of environment e; the multiplicative parameters: 𝜆𝑛 the singular value for interaction principal component axis (ipca) n, gn  the genotype eigenvector for axis n, and𝛿𝑒𝑛the environment eigenvector; ge pca residuals (noise portion) and ger  error term. 3. results and discussion 3.1. analysis of variance the combined analysis of variance for the two seasons and four locations was performed following shapiro-wilk normality test. the analysis of variance revealed that the main effects, genotype (g), location (l), and year (y) showed significant (p ≤ 0.001) differences for grain yield (table 2). the g x l and g x y also showed highly significant (p ≤ 0.01) differences, whereas g x l x y and l x y showed significant and non-significant differences, respectively. highly significant mean squares due to g x l interaction revealed that the genotypes interacted considerably with environmental conditions. similar trends were reported in previous studies by tariku et al. (2013), waghmode and mehta (2011), akter et al. (2015), oladosu et al. (2017), zewdu et al. (2020) for rice. significant differences were observed for grain yield among the test genotypes across the six environments. this suggests the presence of genetic variability among the genotypes in the tested locations. the mean grain yield over six environments ranged from 2.36 tons ha–1 (irat 355) to 4.23 tons ha–1 (yin lu20) with a grand mean of 2.28 tons ha–1 and the standard check (superica-1) gave 2.54 tons ha–1 (table 3). girma et al. east african journal of sciences volume 16(1): 47–56 50 table 2. combined analysis of variance for eleven upland rice varieties evaluated in western ethiopia. source of variations degrees of freedom mean squares replication 2 5.08*** genotype(g) 10 4.90*** location(l) 3 37.00*** year(y) 1 13.78*** g x l 30 1.19** g x y 10 1.71** l x y 1 0.35 g x l x y 10 1.54* residuals 120 0.63 note: ***, ** and * refer to statistical significance at p < 0.0001, p < 0.001 and p < 0.05 probability level, respectively. table 3. mean seed yield (ton ha-1) of rice genotypes across six environments. s/n genotype mean seed yield in tons ha–1 mean 2010 2011 gutin bako boneya bako gutin chewaka 1 wab272-b-b-8-h1 2.85 1.72 3.70 3.72 2.70 2.84 2.92 2 yin lu20 2.67 2.18 4.56 5.89 4.88 5.17 4.23 3 irga370-38-1-1-f-b1-1 3.66 1.78 4.50 1.82 5.71 3.53 3.50 4 cnax3031-15-2-1-1 3.30 1.74 4.18 3.40 4.61 3.76 3.50 5 wab502-8-5-1 3.42 2.41 3.25 2.82 5.17 2.99 3.34 6 wabc165(iac165) 3.23 1.94 4.47 2.27 4.26 3.26 3.24 7 wab450-11-11p31-hb 2.96 1.94 4.21 2.20 5.40 2.88 3.27 8 wab376-b-10-h3 2.93 2.10 4.80 2.76 5.02 3.56 3.53 9 wab368-b-1-h2-hb 2.43 1.55 3.81 3.10 3.39 2.69 2.83 10 irat-335 1.73 1.29 3.75 2.44 2.79 2.16 2.36 11 superica-1 2.50 1.74 3.72 2.46 2.50 2.29 2.54 mean 2.88 1.85 4.09 2.99 4.22 3.19 3.20 lsd 0.902 0.2383 0.5478 0.7016 0.7968 0.4866 0.6896 note: lsd = least significant difference. 3.2. regression analysis 3.2.1. eberhart and russell model mean square due to genotypes was found to be significant (p < 0.01) (table 4). non-significance of genotypes x environments (linear) showed that there were no differences in yield performance among the genotypes under the different environments. the mean performance, regression coefficient (bi) and squared deviations (s2di) from regression values are presented in table 5. genotypes yin lu20 and wabc165(iac165) showed mean yield higher than average, regression coefficient (bi) did not differ significantly from unity and deviation from regression (s2di) approaching to zero. this suggests these genotypes are stable and widely adaptable to the six environments. genotypes, irga370-38-1-1-fb1-1, wab450-11-11p31-hb and wab376-b-10-h3, had bi value significantly different from unity showing that these genotypes are sensitive to change in environment and tend to give high yield at favorable environment. the results consistent with the earlier reports on rice (panwar et al., 2008; kumar et al., 2010; bose et al., 2012; patel et al., 2015; satoto et al., 2016; shrestha et al., 2020a; shrestha et al., 2020b) girma et al. genotype x environment interaction and yield stability in rice 51 table 4. analysis of variance for grain yield using eberhart-russel regression model. source of variation df mean squares total 43 genotype 10 1.22** environment + genotype x environment 33 0.74 environment in linear 1 16.13 genotype x environment (linear) 10 0.33 pooled deviation 22 0.21 residual 88 0.61 note: ** = significant level at p < 0.001 probability level. table 5. stability analysis for grain yield of rice genotypes grown across six environments in western oromia. genotypes regression slope bi deviation from linearity (s2di) mean grain yield (tons ha–1) wab 272-b-b-8-h1 0.5113 0.1741 2.92 yin lu20 1.0190 1.4531 4.23 irga370-38-1-1-f-b1-1 1.5212 0.4665 3.50 cnax3031-15-2-1-1 1.1060 –0.1963 3.50 wab502-8-5-1 0.8256 0.2445 3.34 wabc165(iac165) 1.0798 –0.0731 3.24 wab450-11-11p31-hb 1.3534 0.1459 3.27 wab376-b-10-h3 1.3007 –0.1594 3.53 wab368-b-1-h2-hb 0.8543 –0.1652 2.83 irat335 0.8707 –0.0569 2.36 superica-1 0.5580 –0.0341 2.54 mean 3.20 note: standard error of beta = 0.3365. 3.2.2. additive main effects and multiplicative interaction (ammi) model analysis of variance revealed significant (p<0.01) differences among environments, genotypes, and genotype x environment. these results are in agreement with the findings of nassir and ariyo (2011), tariku et al. (2013), islam et al. (2020), zewdu et al. (2020) for rice at different locations. interaction principal component analysis (ipca) 1 and (ipca) 2 showed significant (p < 0.01) differences, whereas the remaining ipcas were not significant (table 6). the percentage of g x e interaction explained by ipca 1 was 64.55% of the g x e interaction sum of squares. since ipca 1 (at p  0.01) axis was significant and ammi analysis was performed to identify stable genotypes. the ammi analysis result revealed that cnax3031-15-2-1-1 was the most stable genotype having ipca score closer to zero (table 7 and figure 1). however, yin lu20, irga370-38-1-1-f-b1-1 and wab450-11-11p31-hb with ipca score deviate from zero are suitable for specific adaptation. in agreement with the current finding yan et al. (2007), dewi et al. (2014), and sharifi et al. (2017) explained the importance of ammi and biplots in identification of stable varieties. environments such as gutin, boneya and chewaka, produced higher environmental mean yield than the others. this indicates that the varieties performed well in those environments due to proper agronomic practices and favorable environmental condition. girma et al. east african journal of sciences volume 16(1): 47–56 52 table 6. analysis of variance for additive main effects and multiple interaction (ammi). source of variation df mean squares % g x e interaction explained total 197 environments 5 24.997** reps within env. 12 2.422 genotype 10 4.908** genotype x env. 50 1.361** ipca 1 14 3.138** 64.55 ipca2 12 1.263** 22.26 residual 120 0.634 note: grand mean = 3.204; r2 = 0.7810; cv (%) = 24.84; reps = replications; and env. = environment. ** = significant level at p < 0.01 probability level. table 7. ipca1 scores of genotypes and environments. designation of genotypes genotype ipca 1 score mean grain yield (tons ha–1) a wab 272-b-b-8-h1 0.7227 2.92 b yin lu20 1.0929 4.23 c irga370-38-1-1-f-b1-1 –0.9768 3.50 d cnax3031-15-2-1-1 0.0345 3.50 e wab502-8-5-1 –0.4173 3.34 f wabc165(iac165) –0.3407 3.24 g wab450-11-11p31-hb –0.6955 3.27 h wab376-b-10-h3 –0.3265 3.53 i wab368-b-1-h2-hb 0.3187 2.83 j irat335 0.2937 2.36 k superica-1 0.2944 2.54 environments a gutin2010 –0.4856 2.88 b boneya2011 –0.1066 4.09 c bako2010 –0.0575 1.85 d bako2011 1.4795 2.99 e gutin2011 –1.1372 4.22 f chewaka2011 0.3073 3.19 note: ipca = interaction principal component analysis. girma et al. genotype x environment interaction and yield stability in rice 53 figure 1. biplot with abscissa (x-axis) plotting means from 1.854 to 4.225 and with ordinate (y-axis) plotting ipca1 from -1.137 to 1.480. 4. conclusions the results of this study have demonstrated that, according to eberhart and russell model (regression analysis), genotypes yin lu20 and wabc165 (iac165) were found to be stable and widely adaptable. in addition, genotype yin lu20 was found to be a high yielder in most locations. the regression analysis and ammi models revealed that cnax3031-15-2-1-1 was the most stable genotype. however, genotypes irga370-38-1-1f-b1-1 and wab450-11-11p31-hb with ipca scores deviating from zero are suitable for adaptation to specific locations and sensitive to change of environmental conditions. however, genotypes yin lu20 and cnax3031-15-2-1-1 were found to be stable and high yielding and proposed as candidate varieties. accordingly, yin lu20, which was finally named as chewaka variety was selected by farmers for its high seed yield, stability, and resistance to blast and brown spot diseases and therefore, officially released for production in the test environment and areas in the country with similar agroecology. 5. acknowledgements the authors thank oromia agriculture research institute for funding the research. we also thank all staff members of cereal crops research team of bako agricultural research center for their technical support. 6. references agrobase, t.m. 2000. agronomix software inc., 171 waterloo street winnipeg, manitoba, r3n0s4, canada. akter, a., hasan, m. j., kulsum, m., rahman, m., paul, a., et al. 2015. genotype × environment interaction and yield stability analysis in hybrid rice (oryza sativa l.) by ammi biplot. bangladesh rice journal, 19: 83–90. allard, r.w. and bradshaw, a.d. 1964. implication of genotype x environment interaction in applied plant breeding. crop sciences, 4: 403–507. bose, l.k., nagaraju, m. and singh, o.n. 2012. genotype x environment interaction and stability analysis of lowland rice genotypes. journal of agricultural sciences (belgrade), 57: 1–8. (1.854,1.480) (3.204,1.480) (4.225,1.480) ◼ bako2011 . . yin lu20⬧ . wab 272-b-b-8-h1 ⬧ . . . irat335⬧ ⬧ superica-1 ⬧ wab368-b-1-h2-hb ◼ chewaka2011 . . ⬧cnax3031-15-2-1-1 .................................................................... ◼ bako2010 . ◼ boneya2011 . . wabc165(iac165)⬧ ⬧ wab376-b-10-h3 . ⬧wab502-8-5-1 gutin2010◼ . . . ⬧ wab450-11-11p31-hb . . ⬧irga370-38-1-1-f-b1-1 . gutin2011◼ (1.854,-1.137) (3.204,-1.137) 4.225,-1.137) girma et al. east african journal of sciences volume 16(1): 47–56 54 dessie, a, zewdu, z., worede, f. and bitew, w. 2018. yield stability and agronomic performance of rainfed upland rice genotypes by using gge biplot and ammi in north west ethiopia. international journal of research and review, 5(9): 123– 129. dewi, a.k., chozin, m.a., triwidodo, h. and aswidinnoor, h. 2014. genotype × environment interaction, and stability analysis in lowland rice promising genotypes. international journal of agronomy and agricultural research, 5: 74–84. dogara, a. m. and jumare, a. i. 2014. origin, distribution and heading date in cultivated rice. international journal of plant biology and research, 2: 2–6. eberhart, s.a. and russell, w.a. 1966. stability parameters for comparing varieties. crop science, 6: 36–40. fao (food and agriculture organization). 2017. database of agricultural production. fao statistical databases. http://faostat.fao.org/site/339/default. aspx. gauch, h.g. and zobel, r.w. 1996. ammi analyses of yield trials. pp. 85–122. in: kang, m.s. and gauch, h.g. 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ethiopia. net journal of agricultural science, 1: 10–16. lakew, t., dessie, a., tariku, s. and abebe, d. 2017. evaluation of performance and yield stability analysis based on ammi and gge models in girma et al. genotype x environment interaction and yield stability in rice 55 introduced upland rice genotypes tested across northwest ethiopia. international journal of research studies in agricultural sciences (ijrsas), 3: 17–24. lakew, t., tariku, s., alem, t. and bitew, m. 2014. agronomic performances and stability analysis of upland rice genotypes in north west ethiopia. international journal of scientific and research publications, 4: 1–9. waghmode, b. and mehta, h. 2011. genotype x environment interaction and stability analysis in hybrid. crop improvement, 38: 6–12. yan, w. 2001. gge biplot-a windows application for graphical analysis of multienvironment trial data and other types of two-way data. agronomy journal, 93: 1111–1118. yan, w. and l.a. hunt. 2001. interpretation of genotype x environment interaction for winter wheat yield in ontario. crop science, 41: 19–25. yan, w., kang, m.s., ma, b., woods, s. and cornelius, p. l. 2007. gge biplot vs. ammi analysis of genotype‐by‐environment data. crop science, 47: 643–653. zewdu, z., abebe, t., mitiku, t., worede, f., dessie, a., et al. 2020. performance evaluation and yield stability of upland rice (oryza sativa l.) varieties in ethiopia. cogent food and agriculture, 6: 1842679. https://doi.org/10.1080/23311932.2020.1842679 zobel, r.w., wright, j.j. and gauch, h.g. 1988. statistical analysis of yield trial. agronomy journal, 80: 388–393. https://doi.org/10.1080/23311932.2020.1842679 girma et al. east african journal of sciences volume 16(1): 47–56 56 ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15 (1) 17-24 licensed under a creative commons *corresponding author: sisaywube20@gmail.com. attribution-noncommercial 4.0 international license factors driving the expansion of helichrysum splendidum in menz-guassa community conservation area of the afroalpine ecosystem of ethiopia sisay wube 1,2*, debissa lemessa 1, and bikila warkineh dullo 2 1ethiopian biodiversity institute, addis ababa, ethiopia 2department of plant biology and biodiversity management, addis ababa university, ethiopia abstract background: the rapid expansion of helichrysum splendidum shrub into menz-guassa community conservation area has resulted in the scarcity of guassa grasses and this has threatened the livelihoods of the local community. objective: a field survey was undertaken to examine the effect of human disturbance and soil burrows on the expansion of h. splendidum. materials and methods: two transects were laid out along altitudinal gradient with a 200 m interval and 15 quadrats (5 m  5 m each) were arranged on each quadrat at every 100 m for data collection on the level of human disturbance, number of soil burrows, and the abundance of h. splendidum. in total, 90 composite soil samples were collected from three soil layers (litter, 0–3 cm and 3–6 cm) from the five subplots (size: 1 m x 1 m each) which were established in the four corners and one in the center of each quadrat. the soil seed bank study was undertaken in the greenhouse and the seedlings grown were identified to the species level the density of which was recorded. the general linear model (glm) was employed to test the effects of human disturbance and soil burrows on the abundance and density of seedlings of h. splendidum. results: the results showed that abundance of h. splendidum significantly increased with increasing level of human disturbance, but decreased with the increasing number of soil burrows (p < 0.001). higher germination density was recorded from soil seed bank with moderate and high levels of human disturbance compared to soil banks with very high levels human disturbance. however, the density of seedlings showed an increasing trend with increasing the number of soil burrows. conclusion: our overall results suggest that human disturbances (i.e., grass cutting and wood collections) and soil burrowing by mole rats are the major drivers of the expansion of h. splendidum and hence mechanisms that halt such process need be sought to restore the cover of guassa grass on which the livelihoods of the local community largely depend. keywords: afroalpine ecosystem; conservation; disturbance; seed bank; soil burrows 1. introduction the afroalpine ecosystems are characterized by harsh climatic conditions such as low temperature, high solar radiation and strong wind (white, 1983). in this nexus, earlier studies have revealed that the vicinity to the equator and high elevations fundamentally govern the nature of afroalpine climate and the associated ecological processes (yuan et al., 2016). the afroalpine plant life forms are comprised of the giant rosette plants; tussock forming grasses and sedges; acaulescent rosette plants; cushion plants; and sclerophyllous and dwarfshrubs. the guassa community conserved area is found in afroalpine ecosystem of ethiopia where several indigenous and endemic characteristic species such as h.splendidum (thunb.) less festuca macrophylla hochst. exa. rich, kniphofia foliosa hochst, urtica simensis steudel, lobelia rhynchopetalum hemsl, euryops pinifolius a. rich and cynoglossum densefoliatum chiov are dominantly growing (zelalem tefera et al., 2012; habtamu wodaj et al., 2016). in recent years, a rapid expansion of sclerophyllous and dwarf-shrubs such as h. splendidum into the afroalpine grassland or the changing dominance from grasses such as guassa grass (f. macrophylla hochst. exa) to scrub land has been observed in central highlands of ethiopia (girma nigussie et al., 2019), where this study was conducted. guassa grass is biennially harvested for various purposes, such as, rope making, floor mat, fodder, rain hut, whip (giraf) and income generation from the sale of the grass (gomeje amessie, 2014). at the present time, the expansion of h. splendidum has caused the scarcity of guassa grass and this is a worrisome to the local community for their livelihoods rely on the services that this grass provides them (zelalem tefera, 2004; steger et al., 2020). h. splendidum is a shining sclerophyllous dwarf bushy shrub which commonly grows in erica arborea bush land, and in afroalpine grassland within the altitudinal range of 2500–4300m above sea level (hedberg et al., 2004). it belongs to the family of asteraceae that is famous for high seed production and dispersibility. the plant is widely distributed in sisay et al. east african journal of sciences volume 15 (1) 17-24 18 africa with distributional range extending all the way to south africa (hedberg et al., 2004). it is a fastgrowing shrub capable of reaching 1.5 m in height, has aromatic smell and its flowers have a long-lasting sweet scent (hae, 2016). several reports have denoted that essential oil is extracted from this plant has antifungal and antibacterial properties (bruno et al., 2006; lourens et al., 2008; mashigo et al., 2015). recently, research findings have showed that grassland cover is shrinking in menz-guassa community conservation area while the cover of shrub land is dominated mainly by h. splendidum is increasing (girma nigussie et al., 2019). however, the processes driving the expansions of h. splendidum at the expense of f. macrophylla is not fully understood (girma negussie et al., 2019). in menz-guassa community conservation area, shrews, such as crocidura thalia and c. baileyi, and rodent species including porcupine (hystrix cristata), common mole rat (tachyoryctes splendens), unstriped grass rat (arvicanthis abyssinicus), harsh-furred rat (lophuromys flavopunctatus), abyssinian meadow rat (stenocephalemus grisecauda), and groove-toothed rat (otomys typus) are commonly observed (zelalem tefera et al., 2005). burrowing animals increase the porosity of soil and thereby speed up the decomposition of organic debris (zhang and liu, 2003) and this may lead to changes in shrub-grass coexistence (louw et al., 2019). for example, recently, h. splendidum has colonized f. macrophylla in afroalpine ecosystem (sillero-zubiri and macdonald, 1997; girma nigussie, 2019), but the mechanisms that drives such dynamics is not well understood (aramde fetene et al., 2014). the present study explored the factors driving the expansion of h. splendidum in menzguassa community conservation area of afroalpine ecosystem of ethiopia. based on these background evidences, we hypothesized that anthropogenic disturbance and soil borrows are the factors that drive the expansion of h. splendidum in guassa community conservation area. to our knowledge, this study is the first of its kind in ethiopia and there is no known literature on this topic. from the several workshops we have been organizing with the local community, we learned that the expansion of h. splendidum is one of the major threats to the socio-ecological sustainability of the area. currently, h. splendidum shrub is expanding extensively at the expense of the guassa grass (claudio-sillero et al., 1997; ephrem et al., 2011). the local communities are worried about this expansion of this shrub as they think that it may replace the guassa grass which is highly valuable to their livelihoods (personal communication). in line with this, we examined the factors driving the expansion of h. splendidum shrub. 2. methods 2.1. study area the study was conducted in menz-guassa community conservation area which spans 111 km2 in area (fig. 1). it is located between the geographical coordinates of 10o 15–10o27′ n latitude and 39ᵒ45– 39°49′ e longitude in the central highland of ethiopia, north-east of addis ababa between the elevation range of 3200−3700 meters above sea level. guassa is named after the guassa grass (festuca macrophylla) that has multiple benefits for the local communities including thatch, rope, construction material and forage (steger et al., 2018). the rainfall distribution of the area is characterized by a bimodal pattern where the main rainy season is during june to september and the short rainfall season occurs from february to april (gomeje amessie, 2014). the mean annual rainfall is 1650 mm while the mean monthly temperature is 12.3ºc. sisay et al. human disturbance and soil burrows 19 figure 1. the map of the study area (menz-guassa community conservation area) in relation to the map of amhara region and ethiopia. 2.2. study design and data collection data were collected from two transects laid out along an altitudinal gradient with 200 m interval apart from each other. along each transect, 15 quadrats (size = 5 m  5 m each) were laid at 100 m interval. from both of these two transects, in total, 30 quadrats were used for the survey and assessment. first, the level of human disturbance was visually estimated for each quadrat using categorical scale of low (< 10%), moderate (10–20%), high (20–40%) and very high (40). these categories of human disturbance were estimated based on the status of destruction from cutting of h. splendidum within quadrates. secondly, the stems or abundance of h. splendidum and the number of soil burrows were counted for each quadrat. along with this, five subplots (size = 1m x 1m) were established in each quadrat, four at the corner and one at the center to collect composite soil samples and in total 90 composite soil samples from three soil layers (litter, 0-–3cm and 3–6cm) were collected for the soil seed bank study. a one kg composite soil sample was separately stored in plastic bags for each soil layer and transported to addis ababa university greenhouse for soil seed bank study. these soil samples were dried at room temperature and sieved using a 4 mm sieve to remove debris and transferred to 90 perforated circular plastic buckets with 30 cm diameter at the top and depth of 10 cm. this soil seed bank study was undertaken for four months during december, 2017 to april, 2018. the soils were watered every third day to maintain moisture to initiate seed germination. after two months, identification of the seedlings to the species level was made at national herbarium of addis ababa university. the number of germinated seedlings for each species was recorded for two consecutive months by discarding the counted seedlings at the time of recording. 2.3. data analysis the effects of human and soil burrowing disturbances as explanatory factors on the dependent variables, i.e., abundance and the density of germinated seedlings of h. splendidum from soil seed banks were tested using general linear model (glm) with poisson distribution. since we did not find a significant effect of human disturbance on the density of seedlings germinated from each soil layers (surface litter, 0–3 cm, 3–6cm), the data of density of seedlings were pooled together and accordingly the effect of human disturbance was tested. the analysis was conducted using r statistical program (version 3.5.0). 3. results the results of the general linear model analysis showed that the level of human disturbance is positively related to the abundance of h. splendidum (p < 0.001, figure 2). however, the number of soil burrows was negatively correlated with the abundance of h. splendidum (p<0.001, figure 3). moreover, the pooled density of seedlings of h. splendidum significantly varied with the levels of human disturbance (p < 0.001) and the density was higher at moderate and high disturbance levels and lower at low and very high disturbances categories (figure 4). moreover, the pooled density of seedlings was significantly and positively affected by the soil sisay et al. east african journal of sciences volume 15 (1) 17-22 20 burrows where density increased with increasing number of burrows (p < 0.001, figure 5). figure 2. boxplot showing the abundance (number of stems) of h. splendidum within 25 m2 in relation to the disturbance level. the abundance of h. splendidum is higher at higher human disturbance level in menz-guassa community conservation area. figure 3. line graph showing the abundance of h. splendidum in relation to the number of soil burrows in menzguassa community conservation area. abundance decreases with increasing number of soil burrows. figure 4. boxplot showing the pooled density of seedlings emerged from soil seed bank for h. splendidum in menzguassa community conservation area. the density was higher at moderate and high human disturbance while it was lower at two extremes of lower and very high disturbance levels. sisay et al. human disturbance and soil burrows 21 figure 5. line graph showing the pooled density of seedlings emerged from three soils layers for h.splendidum in relation to the number of soil burrows in menz-guassa community conservation area. the density of seedlings increased with increasing the number of soil burrows. 4. discussion not only human and ecological disturbances but also the type and extent of disturbances in natural ecosystems may differently favor a certain plant species across growth structure at the expense of the coexisting species (james, 1999). here, we showed how human disturbances such as cutting fire wood and grass collection and soil burrowing by shrews and rodents differently affected abundance and regeneration of h. splendidum in afroalpine ecosystem in the central highlands of ethiopia. although the density of soil burrows was negatively correlated with the abundance of h. splendidum (figure 3), the density of seedlings emerged from soil seed bank showed an increasing pattern with increasing density of soil burrows (figure 5). similarly, the expansion of h. splendidum was higher at moderate level of human disturbance, but lower at lower and extreme levels of disturbances (figure 4). this trend corroborates the intermediate disturbance hypothesis that states that moderate level of disturbance favors the expansion unlike the low and extreme level of disturbances (wilkinson, 1999; catford et al., 2012). the increasing trend of the expansion of h. splendidum triggered by the different level of disturbances may be related to the exposure of soil mainly litter layer to sunlight and fast decomposition and nutrient availability to plants, improved air circulation in the soil and seed production and dispersal potential of the plant. firstly, the grass harvesting or cutting of shrubs exposes the ground to sun light and heat, and air circulation (wanga et al., 2005). the significance of this factor in ecological processes in extreme environmental conditions such as in the present study area could be more pronounced in speeding up the decomposition of thick litters and open more space for the germination of seeds and growth of seedlings of h. splendidum (wearne and morgan, 2001). secondly, h. splendidum, an asteraceae family, produces abundant small seeds which can easily be dispersed by animals (gomes et al., 2019) and humans may also serve as a dispersal agent while collecting the plant for its appealing smell during smoking in houses and collecting grasses and shrubs. thirdly, the soil burrowing by animals in cold environments are one of the important ecological functions in emulsifying soils (zhang and liu, 2003; lara et al., 2007) through making nutrients available for plants and thus promoting regeneration of plant species (hagenah and bennett, 2012). even if very high level of human disturbance opens up impervious top layer of the bushes and promotes growth, the recruitment process is disrupted and as a consequence seedlings are exposed to extreme environmental conditions such as extreme cold and heat. moreover, due to cumulative effects of very high human disturbance and intensive burrows, plants are liable to strong run off and as a result roots could be exposed to harsh conditions which affect the abundance of h. splendidum. it is an established fact that disturbances affect plant growth pattern and structure (hansen and clevenger, 2005; hill et al., 2005). consistent with our findings, several previous findings have asserted that disturbances including soil burrows expose the roots of the cushion plants and thereby are damaged by the harsh environmental factors and the cumulative impacts of which may negatively attribute to the decreasing of their abundances (zhang et al., 2003; tort et al., 2004; alvarez-aquino et al., 2005; galiano et al., 2014). however, some studies, such as, zelalem tefera, (2012) indicated that soil burrows by rodents has no effect on abundance of plants. the justification given in this regard is that these soil burrows are not habitat selective and effects on species diversity is not significant. results from soil seed bank analysis showed that very high level of human disturbance had negative impact on the density of seedlings of h. splendidum, in contrary to the abundance of h. splendidum where the density of seedlings from soil seed bank increased with increasing number of burrows. likely, this result may indicate that soil burrows facilitate the sisay et al. east african journal of sciences volume 15 (1) 17-24 22 availability of nutrients, moisture and aeration in the soil that promotes germination and growth of seedlings. related to this, wanga et al., (2005) and zhang et al., (2003) have also found that such disturbances create favorable conditions for the germination of seeds in soils. however, leder et al. (2017) showed similar results but noted that higher levels of disturbance disfavored the initiation of germination from soil seed banks. here, more soil burrows imply more soil mixing, soil aeration and higher chance of seed distribution. however, this was not reflected well in the above ground abundance since germinating seedlings in the field may be eaten by rodents or could die due to uprooting during the time of burrowing. this means that human disturbances and soil burrows differently affect the abundance and regeneration of h. splendidum. the overall results suggest that human disturbances and soil burrows have both positive and negative impacts on the abundance and regeneration of h. splendidum shrub species in menz-guassa community conservation area of afroalpine ecosystem. 5. conclusion our findings showed that moderate human disturbance and the soil burrows have favored the expansion of h. splendidum into f. macrophylla grassland. on the contrary, the abundance of h. splendidum shrub was disfavoured at lower and extreme levels of disturbances. this implies that human disturbances (i.e., grass cutting and wood collections) and soil burrowing by mole rats are the major drivers of the expansion of h. splendidum and overall mechanisms that halt such process need be sought to restore the cover of guassa grass on which the livelihoods of the local community largely depend. however, the present study is limited to exploring the effects of two factors; human disturbance and the number of soil burrows on the expansion of h. splendidum and hence further research is suggested to fully understand the whole process of outcompeting, colonization and coexistence of these species in menz-guassa community conservation area of afroalpine ecosystem of ethiopia. 6. acknowledgments this paper is part of the msc thesis of the first author. we thank round four thematic research projects of addis ababa university, graduate students research grant of addis ababa university, ethiopian biodiversity institute, regional capacity building for sustainable natural resource management, and agricultural improvement under climate change (norhed-capsnac) for their research fund support to undertake the study. we also thank mr. admasu fantahun for assisting us during data collection. finally, we appreciate the local community in the study area for their cooperation and willingness to give us information during the scoping survey. 7. references álvarez‐aquino, c., williams‐linera, g. and newton, a.c. 2005. disturbance effects on the seed bank of mexican cloud forest fragments 1. biotropica: the journal of biology and conservation, 37(3): 337–342. ashenafi, z.t. and leader-williams, n. 2005. indigenous common property resource management in the central highlands of ethiopia. human ecology, 33(4): 539–563. ashenafi, z.t., coulson, t., sillero‐zubiri, c. and leader‐williams, n. 2005. behaviour and ecology of the ethiopian wolf (canis simensis) in a 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f., li, y.h. and kallenbach, r.l. 2016. anthropogenic disturbances are key to maintaining the biodiversity of grasslands. scientific reports, 6(1): 1–8. zhang, y. and liu, j. 2003. effects of plateau zokors (myospalax fontanierii) on plant community and soil in an alpine meadow. journal of mammalogy, 84(2): 644–651. zhang, y., liu, j. and du, y. 2004. the impact of plateau zokormyospalax fontanierii burrows on alpine meadow vegetation on the qinghaixizang (tibetan) plateau. acta theriologica, 49(1): 43–51. zong, s., jin, y., xu, j., wu, z., he, h., du, h. and wang, l. 2016. nitrogen deposition but not climate warming promotes deyeuxia angustifolia encroachment in alpine tundra of the changbai mountains, northeast china. science of the total environment, 544: 85–93. sisay et al. east african journal of sciences volume 15 (1) 17-24 24 ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15(2): 191-198 licensed under a creative commons *corresponding author: gezk2007@yahoo.co.uk attribution-noncommercial 4.0 international license. registration of new alfalfa-1086 and alfalfa-ml-99 (medicago sativa l.) varieties gezahagn kebede1*, getnet assefa1, fekede feyissa2, muluneh minta1, mamaru tesfaye1, solomon mengistu1, aschalew tsegahun1, berhanu megersa3, yibrah yacob4, aklilu mekasha5, tekalign yirgu6, worknesh seid3, mezgeb workiye4, and asheber tegegn5 1holetta agricultural research center, p.o. box 31, holetta, ethiopia 2ethiopian institute of agricultural research, p.o. box 2003, addis ababa, ethiopia 3werer agricultural research center, p.o. box 2003, addis ababa, ethiopia 4kulumsa agricultural research center, p.o. box 489, asella, ethiopia 5melkassa agricultural research center, p.o. box 436, melkasa, ethiopia 6wondo-genet agricultural research center, p.o. box 198, wondo-genet, ethiopia abstract background: ethiopia has the highest livestock population in africa. however, the productivity of livestock and the role it plays in the economy of the country is very low. this is mainly because of the inadequate availability of quality feed. enhancing the production of alfalfa could contribute to overcome the shortage of feed in the country and enhance the productivity of all classes of livestock in the country. objective: to evaluate performances of high-yielding and disease-tolerant alfalfa varieties. materials and methods: six introduced alfalfa varieties were tested against a standard check (dzf552) and an old introduction of alfalfa (hairy peruvian) varieties for biomass yield, quality attributes, disease and pest reactions, and other agronomic traits at holetta, kulumsa, debrezeit, melkassa, werer, and pawe agricultural research centers during the 2013 and 2014 cropping seasons. three superior alfalfa varieties (alfalfa-1086, alfalfa-ml-99 and alfalfa-998) were selected from multi-location evaluation trials and the candidate varieties with recently released alfalfa variety (dzf-552) were evaluated under verification trial at kulumsa, melkassa, werer, and wondo-genet agricultural research centers in 2015. results: alfalfa-1086, alfalfa-998, and alfalfa-ml-99 had dry matter (dm) yield advantages of 30, 27, and 23% over hairy peruvian variety, respectively. alfalfa-1086, alfalfa-ml-99 and alfalfa-998 also had crude protein (cp) yield advantages of 109, 89, and 73% over the hairy peruvian variety, respectively. more importantly, alfalfa-1086, alfalfa-ml-99, and alfalfa-998 varieties had cp yield advantages of 55, 41, and 28%, respectively, over the recently released (dzf-552) check variety. the in vitro dry matter digestibility (ivdmd) yield advantages were 66% and 23% for alfalfa-1086; 58 and 17% for alfalfaml-99 and 57 and 16% for alfalfa-998 over the hairy peruvian and recently released standard check variety, respectively. the results revealed that the candidate varieties had better ash, cp, and ivdmd but lower fiber contents when compared to the check varieties. conclusions: the released varieties had advantages of cp and ivdmd yields over hairy peruvian and standard check varieties. moreover, the released varieties had advantages of leaf to stem ratio, cp content, and ivdmd over the two checks. due to the better nutritional quality and yields of cp and ivdmd, the released varieties are very important to improve the livestock production and productivity of smallholder farmers. therefore, the two alfalfa varieties (alfalfa-1086 and alfalfa-ml-99) were approved for cultivation in the low to high altitude areas of ethiopia due to their better yield performance, quality attributes, disease and pest reactions, and other agronomic traits. keywords: adaptation; dry matter yield; quality attributes; reaction; yield stability 1. introduction despite the enormous contribution of livestock to the livelihood of farmers, the availability of poor quality feed resources remains to be the major bottleneck to livestock production in ethiopia (seyoum bediye and zinash sileshi, 1995; zinash sileshi et al., 1995; fekede feyissa et al., 2015a). the traditional livestock production system mainly depends upon poor pasturelands and crop residues, which are usually inadequate to support reasonable livestock production (tsige yohannes, 2000; assefa admassie, 2005). these feed resources are high in fiber, with low to moderate digestibility and low levels of nitrogen (preston, 1995; tsige yohannes, 2000). their crude protein and neutral detergent fiber content ranges gezahegn et al. east african journal of sciences volume 15(2): 191-198 192 between 2.5 to 2 7.5% and 72.6 to 77.8%, respectively. such low-quality feeds are associated with a low voluntary intake, thus resulting in insufficient nutrient supply, low productivity, and even weight loss (hindrichsen et al., 2004). the available feed resources are utilized to support the maintenance requirement of the animals with little surplus left for production. poor animal nutrition and productivity arising from the inadequate supply and low-quality feed are among the major constraints facing livestock production in developing countries (fekede feyissa et al., 2015b). the livestock master plan of ethiopia indicated an estimated national annual feed availability of 81.3, million tons dm in bad weather conditions (shapiro et al., 2015). however, the national annual feed requirement is estimated to be 130 million ton of dm, indicating a negative feed balance of 48.7 million ton of dm is recorded in bad weather conditions (shapiro et al., 2015). forage legumes contribute significantly to livestock production in all crop-livestock production systems. they generally lead to higher intakes and animal production than the grass of comparable digestibility (dewhurst et al., 2003). alfalfa (medicago sativa l.) is often recognized as one of the most important perennial forage legumes worldwide and used as a feed for all classes of domestic animals (barnes et al., 1988). it is widely known as the “queen of the forages” due to its ability to consistently produce high forage yield and quality feed as well as its adaptability to different climatic conditions (kamalak et al., 2005; turan et al., 2009). ruminants fed on alfalfa have higher nutrient intake and digestibility than when fed on other forage legumes and grasses (frame, 2005). alfalfa also provides higher amounts of minerals (mainly calcium, magnesium, potassium, sulfur, iron, cobalt, manganese, and zinc) and vitamins (beta-carotene) than other fodders (frame, 2005). alemayehu mengistu (2002) noted that because of its very high feed value, alfalfa can be used as a supplement for crop residues and natural hay in a mixture of 30% alfalfa and 70% other roughages. to improve the availability of livestock feed in terms of quantity and quality, it is better to cultivate alfalfa forage that has better biomass yield and nutritional quality. the number of alfalfa varieties, which produce better yield and quality, is low in ethiopia. so far, only one alfalfa variety (dzf-552) is officially recommended for cultivation by debrezeit agricultural research center in 2014 (moa, 2014). therefore, to alleviate the existing feed shortage problems, there is a need to introduce and evaluate alfalfa varieties that produce high biomass yield and quality feed to different agro-ecologies of the country. accordingly, two alfalfa varieties (alfalfa-1086 and alfalfa-ml-99) with better dry matter yield, crude protein yield, and in vitro dry matter digestibility yield and nutritive value have been selected and recommended for cultivation from six alfalfa varieties introduced by elfora agro-industries private limited company to bridge the feed shortage problem in ethiopia. thus, this paper presented the description of the two newly released varieties and data on their forage yield performance, nutritional quality, agroecological adaptation, disease reaction, and other morpho-agronomic traits and management recommendations. 2. varietal origin and evaluation six alfalfa varieties (alfalfa-1086, alfalfa ml-99, alfalfa998, alfalfa-cw-830, alfalfa mirage, and alfalfa-fast grow ii) were introduced from abroad by elfora and one adapted but not registered alfalfa variety (hairy peruvian) as a check was used to conduct the national variety trial at holetta, kulumsa, debrezeit, melkassa, werer, and pawe agricultural research centers for two years (2013 and 2014) under supplemental irrigation conditions. but, due to disease and adaptability problems, data from the three varieties (alfalfa-cw-830, alfalfa mirage, and alfalfafast grow ii) were not generated for evaluation. so, only three varieties (alfalfa-1086, alfalfa ml-99, and alfalfa-998) were considered. the varieties were uniformly irrigated at field capacity every 15 days during the dry season of the year. the experiment was laid out in randomized complete block design (rcbd) and replicated three times per treatment. the introduced alfalfa varieties with the check (hairy peruvian) were sown on well-prepared seedbeds in rows of 20 cm apart using a seed rate of 20 kg ha–1. di-ammonium phosphate (dap) fertilizer was applied at the rate of 100 kg ha–1 at planting at each location. plots were hand-weeded during the establishment during the subsequent years of evaluation. based on the overall performances, the three betterperforming alfalfa varieties (alfalfa-1086, alfalfa-ml99, and alfalfa-998) were promoted to a variety verification trial with a recently released check (alfalfadzf-552) at holetta, kulumsa, melkassa, werer, and wondo-genet agricultural research centers during the main cropping season in 2015 (table 1). the varieties were planted in rows of 20 cm apart on a plot size of 10 m by 10 m with a seeding rate of 20 kg ha– 1. at sowing, the recommended rate of dap fertilizer was uniformly applied on the plots at each location. other recommended cultural practices were also applied. the national variety release committee (nvrc) evaluated the varieties at field conditions and based on their evaluation result, the two varieties (alfalfa-1086 and alfalfa-ml-99) were approved for cultivation in april 2016 to be utilized by various endusers. http://www.feedipedia.org/node/4223 gezahegn et al. : registration of alfalfa varieties 193 3. agronomic and morphological characteristics the hairy peruvian variety was the tallest plant (71.8 cm) followed by alfalfa-dzf-552 (65.1 cm). the newly released varieties, alfalfa-1086, and alfalfa-ml99 had average plant height of 64.2 and 63.1 cm, respectively, while alfalfa-998 was the shortest (61.7 cm) plants over the growing seasons and locations (table 1). table 1. average plant height of alfalfa varieties tested at holetta, kulumsa, debrezeit, melkassa, werer, and pawe research centers in 2013 to 2015 cropping seasons. variety location of varietal evaluation mean holetta kulumsa debrezeit melkassa werer pawe alfalfa-1086 70.7b 65.4a 64.1 64.4ab 69.0 51.8b 64.2b alfalfa-ml-99 72.9b 66.5a 59.1 74.5a 59.6 46.2b 63.1b alfalfa-998 76.0ab 55.3b 64.1 55.2b 68.7 50.7b 61.7b check: hairy peruvian 81.9a 69.5a 68.0 71.1a 74.0 66.5a 71.8a mean 75.4 64.2 63.8 66.3 67.8 53.8 65.2 cv (%) 5.5 4.7 8.4 8.2 8.2 7.1 9.3 lsd (5%) 8.3 6.0 10.7 10.9 11.1 7.7 4.1 check variety dzf-552 – – 79.3 45.3 67.8 – 65.1 note: means followed by different letters within a column are significantly different from each other at p< 0.05. cv = coefficient of variation (%); and lsd = least significant difference at 5% probability level. the released alfalfa varieties are perennial herbaceous legumes characterized by their agro-morphological characteristics. the maximum plant height at the forage harvesting stage (50% flowering) was 75 and 70 cm for alfalfa-1086 and alfalfa-ml-99 varieties, respectively. alfalfa-1086 variety was relatively early for the forage harvesting stage when compared to the alfalfa-ml-99 variety. the leaf to stem ratio, crude protein yield, digestible yield, and crude protein (cp) were relatively higher for the alfalfa-1086 than the alfalfa-ml-99 variety. on the other hand, the higher ash, neutral detergent fiber (ndf), acid detergent fiber (adf), acid detergent lignin (adl), and in vitro dry matter digestibility (ivdmd) were recorded for alfalfa-ml-99 variety when compared to the alfalfa1086 variety. however, both released varieties per cut produced a mean of 4 t ha–1 dry matter yield at the forage harvest stage. the varieties adapted to lower to higher altitudes ranging from 750-3000 meters above sea level with an annual rainfall ranging from 850-1200 mm. both varieties had good performance under nitosol and clay loam soil types. the varieties should be sown with a seeding rate of 10-20 kg ha–1 at 20 cm row spacing in early june. at planting, the application of the recommended rate of dap fertilizer enhances the establishment performance of alfalfa varieties. a summary of agronomical and morphological characteristics of the released two alfalfa varieties is presented in table 2. 4. yield performances of varieties over locations the varieties produced different forage dry matter (dm) yields across the test environments during the experimental years (table 3). the highest mean dm yield was recorded at werer (6.1 t ha–1) followed by melkassa (4.8 t ha–1), kulumsa (4.1 t ha–1), and pawe (3.5 t ha–1) while the lowest yield of 2.2 t ha–1 was obtained from holetta agricultural research center. the mean dm yields performance of alfalfa varieties ranged from 3.0 to 3.9 t ha–1 with a mean of 3.6 t ha–1 across the test environments. the highest mean dm yield was recorded for alfalfa-1086 followed by alfalfa998 and alfalfa-ml-99, while hairy peruvian gave the lowest dm yield across the environments. the rank of the varieties for dm yield changed across the test environments indicating the effect of genotype x environment interaction on dm yield performances of the varieties (figure 1). yields advantage of the new varieties over the two check varieties is presented in table 4. the result showed that the candidate varieties had advantages of dm yield, crude protein yield, and digestible yield over unregistered alfalfa check variety (hairy peruvian). on the other hand, the varieties showed crude protein yield and digestible yield advantages over the recently released alfalfa variety (dzf-552) but the candidate varieties did not have dm yield advantages over the recently released variety. the highest dm yield advantage was recorded for alfalfa-1086 (30%) followed by alfalfa-998 (27%) and alfalfa-ml-99 (23%) over hairy peruvian variety. the highest crude protein yield advantage was obtained from alfalfa1086 (109%) followed by alfalfa-ml-99 (89%) and alfalfa-998 (73%) over hairy peruvian variety. similarly, crude protein yield advantages of 55, 41, and 28% were recorded for alfalfa-1086, alfalfa-ml-99, and alfalfa-998 varieties over recently released variety, respectively. the in-vitro dry matter digestibility yield advantages were 66 and 23% for alfalfa-1086; 58 and 17% for alfalfa-ml-99 and 57 and 16% for alfalfa-998 over hairy peruvian and recently released check varieties, respectively. gezahegn et al. east african journal of sciences volume 15(2): 191-198 194 table 2. agronomic and morphological characteristics of alfalfa-1086 and alfalfa-ml-99 varieties. characteristic alfalfa-1086 alfalfa-ml-99 species medicago sativa l. medicago sativa l. variety alfalfa-1086 alfalfa-ml-99 adaptation lower to higher altitude lower to higher altitude altitude (m.a.s.l.) 750–3000 750–3000 rainfall (mm) 850–1200 850–1200 soil type nitosol and clay loam nitosol and clay loam seeding rate (kg ha–1) 10–20 10–20 inter-row spacing (cm) 20 20 planting date early june early june fertilizer rate (kg ha–1) dap 100 dap 100 dap plant height at forage harvest (cm) 60–75 60–70 days to harvesting (50% flowering) 80–90 85–95 leaf to stem ratio 1.10 1.04 yield per cut (t ha–1) forage dry matter: 3–5 3–5 crude protein yield 1.15 1.04 digestible yield 2.88 2.74 fodder quality (%) ash 12.61 13.63 crude protein 29.39 28.19 ndf 44.49 44.56 adf 33.43 33.75 adl 4.63 4.87 ivdmd 73.82 74.07 year of release 2016 2016 breeder/maintainer elfora/harc/eiar elfora/harc/eiar note: m.a.s.l. = meters above sea level; dap = diammonium phosphate; ndf = neutral detergent fiber; adl = acid detergent lignin; adf = acid detergent fiber; ivdmd = in vitro dry matter digestibility; harc = holetta agricultural research center; and eiar = ethiopian institute of agricultural research. table 3. average forage dry matter yield (t ha–1) of alfalfa varieties tested at holetta, kulumsa, debrezeit, melkassa, werer, and pawe research centers in 2013 to 2014 cropping seasons. variety location of varietal evaluation mean holetta kulumsa debrezeit melkassa werer pawe alfalfa-1086 2.2 4.6ab 3.8a 4.3 4.4b 4.3 3.9a alfalfa-ml-99 2.4 4.7a 3.0a 5.9 3.5bc 3.0 3.7a alfalfa-998 2.4 3.7a 3.1a 4.4 5.9a 3.5 3.8a check: hairy peruvian 1.9 3.5c 2.0b 4.7 2.8c 3.1 3.0b mean 2.2 4.1 3.0 4.8 6.1 3.5 3.6 cv (%) 17.0 10.9 17.3 15.3 16.9 21.0 22.0 lsd (5%) 0.8 0.9 1.0 1.5 1.4 1.5 0.5 check variety dzf-552 – – 4.4 3.0 4.2 – 3.9 note: means followed by different letters within a column are significantly different from each other at p< 0.05. cv = coefficient of variation (%); and lsd = least significant difference at 5% probability level. gezahegn et al. : registration of alfalfa varieties 195 figure 1. overall mean dry matter yield performances of the candidate varieties across the test environments. table 4. percent advantages of dry matter, crude protein, and in vitro dry matter digestibility yields of alfalfa varieties over unregistered and recently released standard check varieties. % advantage trait alfalfa varieties alfalfa-1086 alfalfa-ml-99 alfalfa-998 over hairy peruvian dm yield 30.0 23.3 26.7 cp yield 109.1 89.1 72.7 ivdmd yield 65.5 57.5 56.9 over check variety dzf552 dm yield 0.0 –5.1 –2.6 cp yield 55.4 40.5 28.4 ivdmd yield 22.6 16.6 16.2 note: dm = dry matter; cp = crude protein; and ivdmd = in vitro dry matter digestibility. 5. reaction to diseases and pests the released alfalfa varieties (alfalfa-1086 and alfalfaml-99) were tested for their diseases and pests reaction starting from the initial stage of evaluation to verification stage and found to be resistant/moderately resistant to major diseases and pests which can affect the varieties (figures 2 and 3). the diseases and pest effects on the performance of alfalfa varieties were recorded as 0-10% resistant, 1130% moderately resistant, 31-60% moderately susceptible, and 61-100% susceptible. accordingly, the released varieties were found to be resistant to moderately resistant to the recorded major diseases (downy mildew, common leaf spot, aphanomyces root rot, and bacterial wilt) and pests (aphids) in the test locations during the experimental periods. the resistance reaction of the varieties could be integrated with other diseases and pest management strategies for better results. generally, the released varieties are superior in tolerance to major diseases and pests to the standard check. 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 holetta kulumsa d/zeit melkassa werer pawe d ry m at te r y ie ld t / h a locations alfalfa-1086 alfalfa-ml-99 alfalfa-998 gezahegn et al. east african journal of sciences volume 15(2): 191-198 196 figure 2. overall mean response of alfalfa varieties for common diseases. figure 3. overall mean response of alfalfa varieties for aphids. 6. quality attributes the chemical composition and in vitro dry matter digestibility of alfalfa varieties are presented in table 5. the candidate varieties had higher ash, cp, and ivdmd but lower fiber contents than the check varieties. the highest ash content (13.63%) was recorded for alfalfa-ml-99 followed by alfalfa-99 (13.49%) and alfalfa-1086 (12.61%). the released alfalfa varieties (alfalfa-1086 and alfalfa-ml-99) produced the highest cp content. the lowest ndf content was recorded for alfalfa-998 while alfalfa-1086 produced the lowest fiber (adf and adl) contents when compared to other varieties. the highest ivdmd (74.1%) was obtained from alfalfa-ml-99 followed by alfalfa-1086 (73.8%) and alfalfa-998 (71.8%). the candidate varieties had advantages over the check varieties in terms of leaf to stem ratio (lsr), cp, and ivdmd (table 6). alfalfa-1086, alfalfa-ml99 and alfalfa-998 varieties had lsr advantages of 9, 3, and 1% over hairy peruvian, respectively. similarly, lsr advantages of 24, 17, and 15% were recorded for alfalfa-1086, alfalfa-ml-99, and alfalfa-998 varieties, respectively, over the standard check. on the other hand, alfalfa-1086, alfalfa-ml-99, and alfalfa-998 varieties had cp advantages of 60, 54, and 36% over hairy peruvian and 55, 49, and 32% cp advantage over recently released (dzf-552) alfalfa variety, respectively. alfalfa-ml-99 had the highest ivdmd advantages (28.1 and 22.5%) followed by alfalfa-1086 (27.6 and 22.1%) and alfalfa-998 (24.2 and 18.8%) over hairy peruvian and recently released alfalfa varieties, respectively. 0 5 10 15 20 25 downy mildew common leaf spot aphanomyces root rot bacterial wilt d e se as e i n c id e n c e ( % ) common diseases alfalfa-1086 alfalfa-ml-99 alfalfa-998 alfalfa-dzf-552 gezahegn et al. : registration of alfalfa varieties 197 table 5. chemical compositions (%) and in vitro dry matter digestibility (%) of alfalfa varieties. variety ash cp ndf adf adl ivdmd alfalfa-1086 12.61 29.39 44.99 33.43 4.63 73.82 alfalfa-ml-99 13.63 28.19 44.56 33.75 4.87 74.07 alfalfa-998 13.49 25.00 44.38 33.78 4.86 71.84 check: hairy peruvian 11.28 18.37 46.31 38.11 9.44 57.84 check variety dzf-552 11.18 18.98 41.92 35.66 6.75 60.45 note: cp = crude protein; ndf = neutral detergent fiber; adl = acid detergent lignin; adf = acid detergent fiber; and ivdmd = in vitro dry matter digestibility. table 6. percent leaf to stem ratio, crude protein, and in-vitro dry matter digestibility advantages of alfalfa varieties over unregistered and recently released standard check varieties. % advantage trait alfalfa varieties alfalfa-1086 alfalfa-ml-99 alfalfa-998 over: hairy peruvian lsr 8.9 3.0 1.0 cp 60.0 53.5 36.1 ivdmd 27.6 28.1 24.2 over check variety: dzf-552 lsr 23.6 16.9 14.6 cp 54.8 48.5 31.7 ivdmd 22.1 22.5 18.8 note: lsr = leaf to stem ratio; cp = crude protein; and ivdmd = in vitro dry matter digestibility. 7. conclusion the agro-morphological performance and nutritive value of alfalfa varieties varied across the test environments due to the differential response of the varieties to various biotic and abiotic factors. the released alfalfa varieties (alfalfa-1086, and alfalfa-ml99) had better dry matter yield and medium plant height compared to the check varieties and other candidate variety included in this study. the released varieties had advantages of dry matter yield, crude protein yield, and in vitro dry matter digestibility yield over hairy peruvian variety. similarly, the released varieties had advantages of crude protein yield, and in vitro dry matter digestibility yield over the standard check. the nutritional qualities indicated that the released varieties had advantages over the two check varieties in terms of leaf to stem ratio, crude protein content, and in vitro dry matter digestibility. due to the better nutritional quality and yields of cp and ivdmd, the released varieties are very important to improve the livestock production and productivity of ethiopia. based on the yield and nutritional quality performances, both alfalfa varieties (alfalfa-1086 and alfalfa-ml-99) have been released for production in the low and high-altitude areas. the breeder and prebasic seeds of both alfalfa varieties (alfalfa-1086 and alfalfa-ml-99) are maintained by elfora agroindustries pvt. ltd. co. and the feed and nutrition research section of holetta agricultural research center. 8. acknowledgements the authors acknowledge the ethiopian institute of agricultural research for funding the research and elfora agro-industries pvt. ltd. co. for importing the varieties and financial support for the research to develop and release the varieties. special thanks are also due to the staff of the feeds and nutrition research program working in the respective research centers for their smooth implementation of the experiment over years. the animal nutrition research staff of holetta agricultural research center is duly acknowledged for assisting with laboratory analysis. 9. references alemayehu mengistu. 2002. forage production in ethiopia: a case study with implications for livestock production. ethiopian society of animal production, addis ababa, ethiopia. pp. 1–111. assefa admassie. 2005. farm management in mixed crop livestock systems in the northern highlands of ethiopia. phd dissertation, wageningen agricultural university, wageningen, the netherlands. barnes, d.k., goplen, b.p. and baylor, j.e. 1988. highlights in the usa and canada. pp. 124. in: hanson, a.a., barnes, d.k. and hill, r.r. (eds.). alfalfa and alfalfa improvement. vol. 29. madison, academic press. dewhurst, r.j., fisher, w.j., tweed, j.k.s. and wilkins, r.j. 2003. comparison of grass and legume silages for milk production. production responses with different levels of concentrate. journal of dairy science, 86: 2598–2611. gezahegn et al. east african journal of sciences volume 15(2): 191-198 198 fekede feyissa, getnet assefa, gezahagn kebede, alemayehu mengistu, and diriba gelti. 2015a. cultivated forage crops research and development in ethiopia. pp. 89–118. in: alemu yami, getnet assefa and lemma gizachew (eds.). 2015. pasture and rangeland research and development in ethiopia. proceedings of a workshop organized by ethiopian society of animal production (esap), 03 february 2014, eiar, addis ababa, ethiopia. fekede feyissa, gezahagn kebede and getnet assefa. 2015b. dynamics in nutritional qualities of tef and wheat straws as affected by storage method and storage duration in the central highlands of ethiopia. african journal of agricultural research, 10: 3718–3725. frame, j. 2005. medicago sativa l. grassland index. a searchable catalogue of grass and forage legumes. fao, rome, italy. hindrichsen, i.k., osuji, p.o., odenyo, a.a., madsen, j. and hvelplund, t. 2004. effect of supplementation of maize stover with foliage of various tropical multipurpose trees and lablab purpureus on intake, rumen fermentation, digesta kinetics and microbial protein supply of sheep. animal feed science and technology, 113: 83–96. kamalak, a., canbolat, o., erol, a., kilinc, c., kizilsimsek, m., et al. 2005. effect of variety on chemical composition, in vitro gas production, metabolizable energy and organic matter digestibility of alfalfa hays. livestock research for rural development, 17(77):1–9. moa (ministry of agriculture). 2014. crop variety register. issue no 17, 2014. addis ababa, ethiopia. preston, t.r. 1995. tropical animal feeding. a manual for research workers. fao animal production and health paper 126. fao, rome, italy. pp. 305. seyoum bediye and zinash sileshi. 1995. chemical composition, in vitro digestibility and energy value of ethiopian feedstuffs. proceedings of the 3rd annual conference of the ethiopian society of animal production, 27–29 april 1995, addis ababa, ethiopia. pp. 307–311. shapiro, b.i., getachew gebru, solomon desta, asfaw negassa, kidus nigussie, et al. 2015. ethiopia livestock master plan. ilri project report, nairobi, kenya, international livestock research institute (ilri). pp. 129. tsige yohannes. 2000. livestock feed security and associated impacts on sustainable agricultural development. proceedings of the 7th annual conference of ethiopian society of animal production (esap), 26-27 may 1999, addis ababa, ethiopia, pp. 51–61. turan, m., kiziloglu, f.m. and ketterings, q.m. 2009. phosphorus management of lucerne grown on calcareous soil in turkey. journal of plant nutrition, 32: 516–535. zinash sileshi, seyoum bediye, lulseged gebrehiwot and tadesse tekletsadik. 1995. effect of harvesting stage on yield and quality of natural pasture in the central high lands of ethiopia. proceedings of 3rd national conference of the ethiopian society of animal production, 2729, april 1995, addis ababa, ethiopia. pp. 316– 322. ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15 (2) 95-102 licensed under a creative commons *corresponding author. kebede123@yahoo.de attribution-noncommercial 4.0 international license. using principal component factor scores in multiple linear regression models to predict body weight of indigenous chickens from morphometric traits in bench maji zone, southwestern ethiopia kefelegn kebede1*, getachew bekele2, and negassi ameha1 1school of animal and range sciences, haramaya university, p.o. box 138, dire dawa, ethiopia 2department of animal sciences, gambella university, ethiopia abstract background: there is a rich genetic resource base of indigenous chickens in ethiopia. however, the productivity of indigenous chicken in the country and their generic base has not been explored sufficiently through characterization using multivariate analysis. objective: the objectives of this study were to understand complex interrelations among morphometric traits of indigenous chickens and predict body weight using principal component (pc) factor analysis. materials and methods: a total of 660 (180 males and 480 females) randomly selected chickens of age six months and above were used for the study. data were collected on body weight and morphometric traits. results: in factor solution of the pca with varimax rotation of the transformation matrix, two principal components (pcs) were extracted (pc1 and pc2) explaining 75.76% of the total variation in the original variables. pc1 had the largest share (62.43%) of the total variance and had its loadings on comb length, wattle length, wingspan, comb height, shank length, and keel length while the pc2 shared only 13.33% of the total variance with positive loadings on body length, back length, and neck length. prediction model based on pc factor scores accounted for 48% of the variation in the body weight and was more valid than the inter-dependent based models (which accounted for 49% of the variation in the body weight) as it removed multi-collinearity which was present as inter-dependent traits were used in the model. conclusion: according to the findings of this study, body weight can be estimated more accurately from pc factor scores than inter-dependent original morphometric traits (i.e. comb height, comb length, wattle length, neck length, back length, body length, wingspan, shank length, and keel length) and the results obtained could be used by chicken producers and researchers for selection, management purposes and estimating market values of the chickens, since weight is the pivotal point on which animal production thrives. keywords: body weight; correlation; morphometric traits; multivariate analysis; principal component factor analysis 1. introduction ethiopia is endowed with many livestock species with an estimated population of 62.6 million cattle, 31.7 million sheep, 33.0 million goats, and 61.5 million poultry (faostat, 2018). the country has poultry species that have lived, adapted and produced for many years in the country (tadelle et al., 2003; halima, et al., 2007; aberra and tegene, 2011). these poultry species contain a highly conserved genetic reservoir, with a high level of heterozygosity, which may provide the biological material for the development of genetic stocks with improved productivity and adaptability. the commonest is the indigenous chicken genetic resources in the hands of resource-poor farmers who rear these birds under the traditional husbandry system of extensive management. rural backyard poultry production plays a vital role in the rapidly growing economy of the country. it contributes in multiple ways to the livelihood and food security of the rural family (solomon et al., 2008). in any livestock enterprise, body weight is a crucial piece of information that a producer needs to know to make proper management decisions (feeding and breeding management, marketing, health care, choosing replacement males and females etc.). without an accurate measurement of body weight, making sound management decisions is daunting, if not impossible (seifemichael et al., 2013; newton et al., 2019). the increasing need to estimate the body weight of animals to study their growth pattern has led to the development of multiple linear regression (mlr) equations which were designed to predict the body weight of animals from morphometric traits (peters et al., 2007; ajayi et al., 2008; mendes, 2011; khan et al., 2014). however, the biological mailto:kebede123@yahoo.de kefelegn et al. east african journal of sciences volume 15 (2) 95-102 96 interpretation of results obtained from mlr analysis may be misleading because of the existence of a high correlation (multi-collinearity problem) between the predictors that yields a deficiency in the regression model formed (camdeviren et al., 2005; mendes, 2009; eyduran et al., 2010). in the presence of multicollinearity problem, the standard errors of the parameter estimates could be quite high, resulting in unstable estimates of the regression model. in extreme cases, this problem can cause the least-squares parameter estimates to be far from the true values, resulting in incorrect conclusions about relationships between the response and predictor traits. one of the approaches used to avoid this problem is the application of principal component (pc) factor analysis (ogah et al., 2009; yakubu et al., 2009). pc factor scores derived from pc factor analysis offers the opportunity to estimate body weight with a high degree of accuracy and solving the problem of multicollinearity. despite the rich genetic resource base of indigenous chickens in ethiopia, there is dearth of information on multivariate analysis on body weight and morphometric measurements of the animals. specifically, the estimation of body weight from morphometric traits of chickens using pc factor analysis has not been exploited. the main purpose of this study was to understand complex interrelationships among the morphometric traits, investigate relationships between morphometric traits and body weights of indigenous chickens by using orthogonal conformation traits derived from the pc factor scores. the information obtained will aid the management, conservation and selection of indigenous chickens towards improved productivity. 2. materials and methods 2.1. description of the study area this study was conducted in bench maji zone (bmz) which is located in the southwestern part of ethiopia. bmz is found at a distance of about 561 km from addis ababa. it is bordered by kaffa zone in the north, debub omo zone in the north east, sheka zone in the south west, and gambela and the south sudan republic in the southern direction. agroecologically, bmz, consists of 52% lowland (500– 1500 m.a.s.l.), 43% intermediate highland (1500–2300) meters above sea level and 5% highland (>2300 m.a.s.l.). it has an altitude ranging from 500–2500 meters above sea level. the mean annual temperature varies from 15.1 0c–27.5 0c. the mean annual rainfall ranges from 400 mm–2000 mm (figure 1). figure 1. map of the study area. 2.2. methods of sampling and data collection a rapid field survey was made before the actual survey was conducted to explore the available knowledge about the type, distribution, and utility of chicken types. bench maji zone has 10 districts, from which data on distribution and numbers of indigenous chickens were taken. a multi-stage sampling procedure (purposive and random) was applied and hence three districts, namely, north bench, sheko, and south bench were purposively selected based on the information gathered on indigenous chicken population size through a rapid field survey and consultations with woreda (district) agricultural experts and extension agents. kefelegn et al. principal component factor scores to predict weight of chickens 97 2.3. study chickens and traits measured a total of 660 indigenous chickens aged six months and above [220 chickens (60 males and 160 females] from north bench, 220 chickens (60 males and 160 females) from sheko and 220 chickens (60 males and 160 females from south bench) were sampled randomly. body weight and morphometric traits (comb height, comb length, wattle length, neck length, back length, body length, wingspan, shank length, and keel length) were recorded following the recommended fao descriptors for chicken genetic resources (fao, 2012). measuring tapes and a digital balance of 1g precision were used to measure the respective morphometric traits and bodyweights of the sampled chickens. 2.4. data management and statistical analysis all statistical analyses were performed using the sas 9.4 software (version 9.4; sas institute inc., nc, 2014). the analyses were carried out on the females in order to avoid potential sampling bias due to the low number of males (bene et al., 2007; ndumu et al., 2008; and traore’ et al., 2008). 2.4.1. exploratory data analysis the body weight and morphometric traits were subjected to exploratory data analysis to get results of descriptive statistics and correlation coefficients using the proc univariate and proc corr procedures of sas (version 9.4; sas institute inc., nc, 2014). 2.4.2. principal component (pc) factor analysis estimating the number of pcs in this study, the criteria kaiser–guttman rule, the scree test, and parallel analysis plot were used for determining the number of pcs to be extracted. kaiser–guttman rule: this rule states that the number of pcs to be extracted should be equal to the number of pcs having an eigenvalue greater than one. eigenvalues measure the amount of variation explained by each pc and will be largest for the first pc and smaller for the subsequent pcs. scree test: plotting the eigenvalues against the corresponding pc produces a screen plot that illustrates the rate of change in the magnitude of the eigenvalues for an increasing number of pcs. the rate of decline tends to be fast first and then levels off. the “elbow,” at which the curve bends, is considered to indicate the maximum number of pcs to extract. parallel analysis: to support the decision making in the selection of the number of pcs extracted, a graphical method known as parallel analysis is used to enhance the interpretation. the correct number of pcs is selected at the cut-off point, where the scree plot and the parallel analysis curve intersect. pc loading: these are correlation coefficients between the original traits and the pc scores. a high positive correlation between pc1 and a trait indicates that the trait is associated with the direction of the maximum amount of variation in the dataset. a strong correlation between a trait and pc2 indicates that the trait is responsible for the next largest variation in the data perpendicular to pc1, and so on. 2.4.3. multiple linear regression (mlr) models multiple linear regression procedure was used to obtain models for predicting body weight from morphometric traits (i), and pc factor scores (ii) bw = b0 + b1x1 + … + bkxk (i) bw = b0 + b1pc1 + … + bkpck (ii) where, bw is the body weight, „bo‟ is the intercept, b1 is the ith partial regression coefficient of the ith morphometric trait, xi or the ith pc. 3. results and discussion 3.1. exploratory data analysis the means and coefficients of variation calculated for the evaluated traits (table 1) were consistent with those reported in the literature for chicken by by eskindir (2012) and hailemichael (2014). however, the values for chest shank length, body length, wing span, comb length and body weight were higher than the findings of melaku (2016). these differences found in the different region might be connected with the high influence of the environment on these traits such as temperature, feed supply and health challenges. as observed in table 1, according to the coefficient of variation (cv), there were two groups of traits. the first group consisted of traits with cvs < 10%, and the second group consisted of traits with cvs > 10%. wattle length was observed to be the variable of greatest instability. the correlation coefficients varied from 0.17 (between body weight and back length) to 0.89 (between wattle length and comb length). among the 45 possible pairs of correlations, all pairs of correlations were found to be significant at p<0.001 (table 2), indicating that the data is suitable for performing pca. such positive and very highly significant correlation coefficient values have also been reported in chickens by the studies of eskindir (2012) and hailemichael (2014). high positive correlations suggest that selection for a trait may lead to a correlated response in the other trait, thus providing a basis for the genetic manipulation and improvement of the native stock. kefelegn et al. east african journal of sciences volume 15 (2) 95-102 98 table 1. descriptive statistic results of body weight and morphometric traits. s/n trait label mean ± se std cv min. max. 1 comb height (cm) ch 1.29±0.03 0.66 51.21 0.10 4.50 2 comb length (cm) cl 3.19±0.05 1.34 41.89 1.00 7.00 3 wattle length (cm) wl 1.65±0.04 1.14 69.05 0.10 6.00 4 neck length (cm) nl 16.79±0.06 1.49 8.86 13.00 21.00 5 back length (cm) bal 20.32±0.05 1.33 6.54 17.00 23.00 6 body length (cm) bl 37.11±0.09 2.19 5.90 32.00 44.00 7 wingspan (cm) ws 58.78±0.19 4.86 8.27 50.00 69.00 8 shank length (cm) sl 8.82±0.04 1.10 12.47 6.00 12.00 9 keel length (cm) kl 10.69±0.04 1.02 9.54 8.00 13.00 10 body weight (kg) bw 1.30±0.01 0.24 18.44 0.70 2.00 note: se = standard error of mean; std = standard deviation; cv = coefficient of variation; min.= minimum; and max. = maximum. table 2. phenotypic correlations and their statistical significance levels among body weight and morphometric traits of chickens in bench maji zone, southwestern ethiopia. trait ch cl wl nl bal bl ws sl kl bw ch 1.00 cl 0.79 1.00 wl 0.79 0.89 1.00 nl 0.44 0.47 0.45 1.00 bal 0.31 0.30 0.35 0.21 1.00 bl 0.49 0.51 0.53 0.79 0.73 1.00 ws 0.69 0.79 0.81 0.52 0.36 0.58 1.00 sl 0.66 0.75 0.76 0.49 0.41 0.58 0.79 1.00 kl 0.49 0.61 0.60 0.32 0.31 0.42 0.60 0.68 1.00 bw 0.61 0.66 0.66 0.39 0.17 0.38 0.61 0.54 0.47 1.00 note: ch = comb height; cl = comb length; wl = wattle length; nl = neck length; bal = back length; bl = body length; ws = wingspan; sl = shank length; kl = keel length; and bw = body weight. 3.2. pc factor analysis anti-image correlations computed (not given here) showed that partial correlations were low, indicating that true factors existed in the data. this result is consistent with that of kaiser-meyer-olkin (kmo) measure of sampling adequacy studied from the diagonal of partial correlation, revealing the proportion of the variance in the body measurements caused by the underlying factor (khan et al., 2010). the kmo measure of sampling adequecy was found to be sufficiently high with a value of 0.782. eyduran et al. (2010) reported that a kmo measure of 0.60 and above is considered adequate. bartlett’s sphericity test for testing the null hypothesis that the correlation matrix is an identity matrix was used to verifying the applicability of pca. the value of bartlett’s sphericity test was significant (p-value = 0.001), implying that the pca is applicable to the data set. 3.2.1. eigenvalues, percentage of total variance with rotated component matrix and communalities the eigenvalue of the total variance, the rotated component matrix and communalities of the traits investigated are presented in table 3. table 3 shows how much of the total variance of the observed traits was explained by each of the pcs after varimax rotation of the component matrix. two pcs were identified with eigenvalues of 5.62 (pc1) and 1.20 (pc2). pc1 explained 62.43% of the total variance while pc2 explained only 13.33%. accordingly, the first two pc factors combined accounted for 75.76% of the total variability present in the parameters measured. the communalities are the proportion of variance that each variable has in common with other variables. thus if communality of a trait is high, it means that the extracted factors explained a big proportion of the variance of the trait. the communality values ranged from 0.568 (nl) to 0.977 (bl) indicating that the data are conformable to pc factor analysis. pc loadings presented in table 3 are the correlation coefficient between the first two pc scores and the original traits. they measure the importance of each morphometric trait in accounting for the variability in the pc. that is, the larger the loadings in absolute terms, the more influential the variables are in forming the new pc and vice versa. the first factor (pc1) loaded heavily on comb length (0.909), wattle length (0.901), wingspan (0.831), comb height (0.820), shank kefelegn et al. principal component factor scores to predict weight of chickens 99 length (0.807), and keel length (0.713) while the second factor (pc2) loaded heavily on body length (0.930), back length (0.810), and neck length (0.662). the loading classification found in this study is somewhat similar to those reported by uda (yakubu et al., 2009), and immature uda (salako, 2006). table 3. eigenvalues and shares of the total variance of indigenous chickens along with factor loadings after varimax rotation and communalities in bench maji zone, southwestern ethiopia. trait pc1 pc2 communalities comb height 0.8197 0.2269 0.7234 comb length 0.9090 0.2134 0.8719 wattle length 0.9010 0.2445 0.8716 neck length 0.3599 0.6620 0.5678 back length 0.1225 0.8098 0.6708 body length 0.3347 0.9301 0.9770 wing span 0.8311 0.3370 0.8043 shank length 0.8067 0.3620 0.7819 keel length 0.7127 0.2044 0.7819 eigenvalue 5.6188 1.1996 % of total variance 62.43 13.33 75.76 a scree-parallel analysis plot of eigenvalues against their pcs is shown in figure 2 below. the plot demonstrates the distribution of variance among the components graphically. for each pc, the corresponding eigenvalue is plotted on the y-axis. by definition, the variance of each component is less than the preceding one. here there appears to be a marked decrease in downward slope after the second pc implying that we can summarize the nine morphometric traits by the first two pcs. figure 2. scree and parallel analysis plots. 3.2.2. mlr models used for body weight prediction of chickens the interdependent original morphometric traits and their independent pc factor scores were used to the predict body weight of chickens. table 4 presents the regression coefficient, their standard errors, t-value, pvalues, variance inflation factor (vif) values, and r2 obtained from mlr analysis. the regression of body weight on ch, cl, wl, ws, and kl was significant, while it was not significant for nl, bal, bl, and sl. the present findings are consistent with the submissions of peters et al. (2007) in chickens and teguia et al. (2008) in ducks. 0 1 2 3 4 5 6 0 1 2 3 4 5 6 7 8 9 e ig e n v a lu e number of pcs eigenvalues kefelegn et al. east african journal of sciences volume 15 (2) 95-102 100 table 4. mlr of body weight on original morphometric traits of indigenous chickens and their pc factor scores in bench maji zone, southwestern ethiopia. model coefficient se t-value p-value vif original morphometric traits as predictors intercept 0.6972 0.17 4.14 <0.0001 – comb height 0.0592 0.02 3.38 0.0008 3.03 comb length 0.0370 0.01 3.03 0.0025 6.00 wattle length 0.0510 0.01 3.48 0.0005 6.31 neck length 0.0185 0.02 1.15 0.2520 13.05 back length –0.0082 0.02 –0.50 0.6143 10.64 body length –0.0078 0.01 –0.49 0.6269 27.64 wingspan 0.0060 0.00 2.21 0.0277 3.93 shank length –0.0127 0.01 –1.10 0.2738 3.68 keel length 0.0209 0.01 2.29 0.0221 1.96 r2 = 0.49; r2 adjusted = 0.49 orthogonal morphometric traits as predictors intercept 1.296 0.01 192.70 <0.000 – pc1 0.185 0.01 24.33 <0.000 1.0 r2 = 0.36; r2 adjusted = 0.36 intercept 1.296 0.01 192.70 <0.000 – pc1 0.185 0.01 24.33 <0.000 1.0 pc2 0.278 0.02 12.44 <0.000 1.0 r2 = 0.48; r2 adjusted = 0.48 to increase meat and egg yields from chicken production, the genetic improvement of body weight is necessary and this requires adequate knowledge of correlated traits that can be considered when selection is to be applied. however, the use of inter-dependent predictors should be treated with caution, since multicollinearity is associated with unstable estimates of regression coefficients (ibe, 1989; malau-aduli et al., 2004; yakubu, 2009) rendering the estimation of unique effects of these predictors impossible. this is evident in the present study, where beak length, neck length, and back length had vif values greater than 10. rook et al. (1990) stated that vif values above 10 indicate severe collinearity which leads to unstable estimation of the associated least square regression coefficient. to overcome this limitation, the pc factor scores are used as predictors for the prediction of body weights (keskin, 2007; ogah et al., 2009; yakubu et al., 2009). these pcs are orthogonal to each other and are more reliable in weight estimation. in the present study, the use of pc1 as a single predictor explained 38% of the total variability in body weight. however, pc1 and pc2 together accounted for 48% of the variation in body weight of the chickens. the two factors selected were found to have a significant (p < 0.0001) positive linear relationship with body weight (table 4). in other words, body weight is expected to increase as the values of factor 1 and 2 scores increase. similarly, shahin and hassan (2000) derived regression equations for estimating the body weight of rabbits using independent factor scores. in another related study, mccracken et al. (2000) obtained a regression model for body weight prediction using principal component scores of musk ducks; while keskin et al. (2007) used factor scores derived from ten body measurements to predict the carcass weight of sheep. 4. conclusions in this study, pc factor analyses were explored in identifying patterns and determine the interdependence in nine morphometric traits of indigenous chickens to eliminate redundancy and predict body weight. according to the results of this study, it could be concluded that using inter-dependent morphometric traits as predictors in mlr analysis resulted in a multi-collinearity problem. on the other hand, when independent orthogonal indices (pc factor scores) were used as predictors, problem of multi-collinearity was removed. the results of this study imply that body weight can be estimated more accurately from principal component (pc) factor scores and the results obtained could be used by poultry producers and researchers for selecting, managings, and estimating market values of chickens. this is because body weight is the pivotal determinant for thriving animal production. however, further research is needed to investigate the relationship between body weight with morphometric traits in the same and other ecotypes of chickens in the different region of the country with a larger number of observations. kefelegn et al. principal component factor scores to predict weight of chickens 101 5. acknowledgements haramaya university is acknowledged for supporting the research financially. moreover, the authors are grateful to the district and kebele office authorities and data collectors and respondents involved in this study. 6. references aberra, m. and tegene, n. 2011. phenotypic and morphological characterization of indigenous chicken populations in southern region of ethiopia. animal genetic resources, 49: 19–31. ajayi, f., ejiofor, o. and ironke, m.o. 2008. estimation of body weight from linear body measurements in two commercial meat-type chickens. global journal of agricultural sciences, 7: 57–59. bene, s., nagy, b., nagy, i., kiss, b., polgár, 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using body measurements. revista udo agricola, 9: 963–967. yakubu, a. 2009. fixing collinearity instability in the estimation of body weight from morphobiometrical traits of west african dwarf goats. trakia journal of sciences,7: 61–66. http://www.fao.org/avianflu/en/farmingsystems.html http://www.fao.org/avianflu/en/farmingsystems.html https://hdl.handle.net/10568/4072 ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15(2): 183-190 licensed under a creative commons *corresponding author: gezk2007@yahoo.co.uk attribution-noncommercial 4.0 international license. registration of new napier grass varieties: zehone-02 and zehone-03 gezahagn kebede1*, fekede feyissa2, getnet assefa1, muluneh minta1, mamaru tesfaye1, solomon mengistu1, aschalew tsegahun1, yibrah yacob3, tekalign yirgu4, and mezgeb workiye3 1holetta agricultural research center, p.o. box 31, holetta, ethiopia 2ethiopian institute of agricultural research, p.o. box 2003, addis ababa, ethiopia 3kulumsa agricultural research center, p.o. box 489, asella, ethiopia 4wondo-genet agricultural research center, p.o. box 198, wondo-genet, ethiopia abstract background: napier grass is a pioneer perennial forage crop and performs well in diverse environments. it produces a high biomass yield and could be also categorized as high-quality forage, which is highly palatable when young and leafy. objective: to register and release high yielding, stable, and disease tolerant napier grass varieties. materials and methods: ten napier grass varieties including a standard check (ilri-16984) were tested for forage dry matter yield, herbage quality, pest and disease reaction, and other agromorphological characteristics across three locations (holetta, debrezeit, and hawassa agricultural research centers) during the main cropping seasons of 2011–2014. based on the overall performance, three superior varieties (16791, 15743, and 16819) were selected and verified with the standard check at holetta, kulumsa, and wondo-genet agricultural research centers during the main cropping season of 2016. results: the results indicated that the candidate varieties had significant forage dry matter yields, crude protein contents, and digestible yields advantages over the standard check. among the varieties, zehone-02 (16791) had the highest advantages of forage dry matter yield, crude protein content, and digestible yield over the standard check and other candidate varieties. moreover, the candidate varieties had advantages of leaf to stem ratio, crude protein content, and in vitro organic matter digestibility over the standard check. based on the criteria of the eberhart and russell regression model, zehone-02 (16791) and zehone-03 (16819) varieties had better mean forage dry matter yield but less stable when compared to the standard check. conclusions: among the tested candidate varieties, zehone-02 (16791) variety was released for its better forage dry matter yield, while zehone-03 (16819) variety for its thin-stemmed nature stature. therefore, both napier grass varieties (zehone-02 and zehone-03) were released in 2017 for production in the mid and high altitude areas and similar agro-ecologies in the country. keywords: adaptation; agro-morphological characteristics; dry matter yield; quality attributes; reaction; yield stability 1. introduction napier grass [pennisetum purpureum (l.) schumach], also known as elephant grass, originated in subsaharan tropical africa (clayton et al., 2013) and occurs naturally throughout tropical africa and particularly in east africa (lowe et al., 2003; mwendia et al., 2006). it is a pioneer forage crop species and performs well in low, mid, and highland areas of ethiopia (tessema zewdu, 2005). according to fekede feyissa et al. (2005), napier grass grows best at high temperatures but can tolerate low air temperatures under which the yield can be reduced and ceases to grow at a temperature below 10 °c. napier grass is propagated vegetatively by using stem cuttings, root splits, or shoot tips (tessema zewdu, 2008) which usually vary across agro-ecologies (getnet assefa and gezahagn kebede, 2012). for best establishment and productivity, it should be planted at the distance of 1 m between rows and 0.5 m between plants (tessema zewdu, 2008). however, the spacing could vary based on the climatic conditions of the area. narrower spacing is often used for moisturestressed areas when compared with high moisture areas (gezahagn kebede et al., 2017). amongst the improved forage crops promoted in ethiopia, napier grass could play an important role in providing a significant amount of biomass yield of 20 to 30 t dm ha–1 year–1 with good agronomic and management practices (farrell et al., 2002). napier grass can provide a continual supply of green forage throughout the year and best fits all intensive small-scale farming systems (alemayehu mengistu, 1997). the yield performance of napier grass genotypes is heavily influenced by agro-ecology, climatic gezahegn et al. east african journal of sciences volume 15(2): 183-190 184 conditions, management practices, and edaphic factors. genotypic variation in growth characteristics of napier grass has also been reported (mwendia et al., 2006) and growth and morphological characteristics are correlated with dry matter yield and nutritional quality (tudsri et al., 2002). the cultivation of highquality forages with high yielding ability and adaptability to biotic and abiotic environmental stresses is one of the possible options to increase livestock production under smallholder farmers’ conditions (tessema zewdu, 1999). despite the huge livestock population in the country, the productivity of animals in ethiopia is lower than the regional and continental average. among the factors contributing to low productivity, the availability of poor-quality feed resources remains to be the major bottleneck to livestock production. because most smallholder livestock producers predominantly own small and fragmented pieces of land, grasses such as napier grass offer a best-fit alternative to other feed options, as these are high-yielding forage plants that require a minimum amount of inputs and acreage. the yield of napier grass mainly depends on the type of cultivar used which in turn is influenced by both the environment and management practices employed. to improve livestock production, sustainable solution to seasonal deficiencies in feed availability and quality are required through proper management and utilization of developed forage crops. the number of released napier grass varieties is too small in the country. so far, only one napier grass variety (ilri-16984) has been released by holetta agricultural research center in 1984 (moa, 2017) which produces low yield and quality when compared to the yields and quality of the current released varieties. livestock production is highly constrained by the low quantity and quality of feed in ethiopia particularly in the drier seasons. napier grass variety, which produces better forage yield and quality per unit area, is a prerequisite to reduce the feed shortage problem of the country. so, testing the adaptability and yield potential of napier grass varieties across various agro-ecological zones is very important to identify the best-bet varieties for efficient utilization. accordingly, two napier grass varieties, named zehone-02 (16791) and zehone-03 (16819) have been officially released owing to their better yield potential and quality to address the feed demand of mixed croplivestock farming systems. therefore, this paper presents the forage yield performance, herbage qualities, agro-ecological adaptation, reaction to major diseases and pests, and other morpho-agronomic and management recommendations for the recently developed and released napier grass varieties (zehone-02 and zehone-03) in ethiopia. 2. varietal evaluation ten napier grass varieties including the standard check (ilri-16984) were considered to select the best performing varieties for release. the experiment was conducted under field conditions at holetta, debrezeit, and hawassa during the main cropping seasons of 2011 to 2014. the varieties were planted at the beginning of the main rainy season in three agricultural research centers. the varieties were planted in a 4 m x 4 m plot using a randomized complete block design (rcbd) with three replications and the varieties were assigned randomly to plots within the block. root splits at holetta and stem cuttings at debrezeit and hawassa were planted in four rows per plot. stem cuttings with three nodes were planted to the depth of 15 to 20 cm at an angle of 45°. a total of 32 root splits/stem cuttings were planted per plot with the intra and inter-row spacing of 0.5 and 1 m, respectively. there was an alleyway of 2 m width between blocks and 1m width between plots. a blanket basal fertilize was uniformly applied to all plots in the form of diammonium phosphate (dap) at the rate of 100 kg ha–1. after every harvest, the plots were top-dressed with 50 kg ha–1 n in the form of urea, of with one-third applied at the first shower of rain and the remaining two-third applied during the active vegetative growth stage of the plant. plots were hand-weeded during the establishment and subsequent years. based on the overall performance, three best performing napier grass varieties (16791, 15743, and 16819) were selected for a variety verification trial with a standard check (ilri-16984) at holetta, kulumsa, and wondo-genet agricultural research centers in the 2016 cropping season. the varieties were planted per plot with the intra and inter-row spacing of 0.5 and 1 m apart, respectively on a plot size of 10 m x 10 m. at planting, the recommended fertilizer rate was uniformly applied on the plots at each location. the national variety release committee (nvrc) evaluated the varieties under field conditions in october 2016 and based on the results of their evaluation, two varieties (16791 and 16819) were released in april 2017 to be used by various end-users. the mean plant heights of the varieties over locations are shown in table 1. gezahegn et al. registration of napier grass 185 table 1. average plant height (cm) of napier grass varieties as compared to the standard check tested at holetta, debrezeit, and hawassa in the 2013–2014 cropping seasons. variety location for varietal evaluation mean holetta debrezeit hawassa 16791 124.8a 172.8a 158.8a 152.1a 15743 115.8a 132.8b 149.5ab 132.7b 16819 88.3b 124.3b 139.5c 117.4c ilri-16984 (standard check) 106.6ab 125.0b 144.7bc 125.4bc mean 108.9 138.7 148.1 131.9 cv (%) 10.7 5.4 3.3 7.9 lsd 23.3 14.9 10.0 10.1 note: means followed by different letters within a column are significantly different from each other at p< 0.05. cv = coefficient of variation (%); and lsd = least significant difference at 5% probability level. 3. agro-morphological characteristics the registered varieties are well adapted to mid and highland areas ranging in altitude from 1500 to 2500 meters above sea level. the varieties performed very well in the areas with annual rainfall ranging from 700 to 1200 mm. the released varieties, named zehone-02 (16791) and zehone-03 (16819), have better performance when planted in red nitosol areas. napier grass is propagated vegetatively by using stem cuttings, root splits, or shoot tips, which usually vary across agro-ecologies. for best establishment and productivity, it should be planted at the distance of 1m between rows and 0.5 m between plants, giving a population of 20,000 plants ha–1. stem cuttings with three nodes are planted to the depth of 15 to 20 cm at an angle of 45o. application of the recommended dap fertilizer rate at planting and split application of urea fertilizer using the recommended rate after every harvest is very important to boost the yield and quality of napier grass varieties. the released varieties should be harvested at 1 to 1.5 m height to get optimum biomass yields and herbage quality. the recorded numbers of tillers are 32 and 38 and the leaf to stem ratio is 1.12 and 1.17 for zehone02 and zehone-03 varieties, respectively. the mean forage dry matter (dm) yield (14 and 10 t ha–1), crude protein (cp) yield (0.9 and 0.7 t ha–1), and digestible yield (6.8 and 4.9 t ha–1) are recorded for zehone-02 and zehone-03 varieties, respectively. zehone-03 variety has lower neutral detergent fiber (ndf), acid detergent fiber (adf), and acid detergent lignin (adl) indicating better in vitro organic matter digestibility (ivomd) when compared to zehone-02 variety. generally, both released varieties (zehone-02 and zehone-03) have similar crude protein (cp) content but zehone-02 variety has relatively higher ash content. a summary of agro-morphological characteristics of the released two napier grass varieties is indicated in table 2. 4. yield performance and stability combined analysis indicated that forage dm yield varied significantly among the tested varieties (table 3). forage dm yield ranged from 8.0 to 13.0 t ha–1 with a mean of 9.9 t ha–1. generally, zehone-02 variety produced the highest forage dm yield followed by 15743 and zehone-03 while the standard check (ilri16984) gave the lowest dm yield. forage dm yield differences occurred due to variations among the tested varieties and testing environments. the rank of the varieties for forage dm yield did not vary across the test environments indicating nonoccurrence of the varietal interaction for this trait across the test environments (figure 1). when genotypes perform consistently across locations, breeders can effectively evaluate genotypes with a minimum cost in a few locations for the ultimate use of the resulting varieties across wider geographic areas. however, with high genotype by location interaction effects, genotypes selected for superior performance under one set of environmental conditions may perform poorly under different environmental conditions. the result indicated that the candidate varieties have forage dm yield, cp yield, and digestible yield advantages over the standard check (table 4). generally, zehone-02 variety gave the highest forage dm yield, cp yield, and ivomd yield advantages over the standard check followed by 15743 and zehone-03 varieties. gezahegn et al. east african journal of sciences volume 15(2): 183-190 186 table 2. agronomical and morphological characteristics of 16791and 16819 varieties of napier grass. characteristics 16791 16819 species pennisetum purpureum pennisetum purpureum variety name zehone-02 zehone-03 adaptation for red nitosol areas for red nitosol areas altitude (m.a.s.l.) 1500–2500 1500–2500 rainfall (mm) 700–1200 700–1200 seeding rate (number ha–1) 20,000 plants 20,000 plants intra row spacing (cm) 50 50 inter row spacing (cm) 100 100 planting materials root splits/ stem cuttings root splits/ stem cuttings planting date mid-june to mid-july mid-june to mid-july fertilizer rate (kg ha–1) dap 100 kg dap or 46/18 kg n/p2o5 100 kg dap or 46/18 kg n/p2o5 urea 108.7 kg urea or 50 kg n 108.7 kg urea or 50 kg n time of fertilizer application dap at planting at planting urea 1/3 at the start of rain and 2/3 at active growth stage 1/3 at the start of rain and 2/3 at active growth stage plant height at forage harvest (cm) 100–150 100–150 number of tillers per plant 32 38 leaf to stem ratio 1.12 1.17 yield per cut (t ha–1) forage dry matter 12–16 8–12 cp yield 0.79–1.05 0.54–0.85 digestible yield 6.63–7.05 4.56–5.25 fodder quality (g kg–1 dm) ash 149.5 147.9 cp 60.5 60.5 ndf 778.4 728.5 adf 492.8 461.4 adl 67.3 67.2 ivomd 510.3 512.0 year of release 2017 2017 breeder/maintainer harc/eiar harc/eiar note: m.a.s.l. = meters above sea level; dap = diammonium phosphate; ndf = neutral detergent fiber; adl = acid detergent lignin; adf = acid detergent fiber; ivomd= in vitro organic matter digestibility; harc = holetta agricultural research center; and eiar = ethiopian institute of agricultural research. table 3. average forage dry matter yield (t ha–1) of napier grass varieties as compared to the standard check tested at holetta, debrezeit hawassa in the 2013–2014 cropping seasons. variety location for varietal evaluation mean holetta debrezeit hawassa 16791 10.5 14.9a 13.5a 13.0a 15743 8.9 11.9b 8.6b 9.8b 16819 7.4 11.3bc 8.0b 8.9bc ilri-16984 (standard check) 7.0 9.4c 7.6b 8.0c mean 8.5 11.9 9.4 9.9 cv (%) 18.4 8.1 10.1 14.5 lsd 3.1 1.9 1.9 1.4 note: means followed by different superscript letters within a column are significantly different from each other at p< 0.05. cv = coefficient of variation (%); and lsd = least significant difference at 5% probability level. gezahegn et al. registration of napier grass 187 figure 1. forage dry matter yield performance of candidate varieties across the test environments. according to eberhart and russell's (1966) model, genotypic performance is generally expressed in terms of three parameters; mean yield, regression coefficient (bi), and the deviation from regression (s2di). according to this model, a genotype should have a high mean yield, bi = 1 and s2di = 0 to decide its stability. according to finlay and wilkinson (1963), bi approximating close to 1.0 indicates average stability, but always be associated and interpreted with the genotype mean yield to determine adaptability. when the regression coefficients for genotypes are approximate to 1.0, deviation from regression close to zero, and are associated with high mean yield, genotypes are adapted to all environments. however, when associated with low mean yield, genotypes are poorly adapted to all environments. the standard check (ilri-16984) has a minimum deviation from regression and regression coefficient close to 1.0. based on the criteria of the eberhart and russell (1966) regression model, the standard check variety can be considered as more stable but gave the lowest forage dm yield. on the other hand, varieties zehone02 (16791), 15743, and zehone-03 (16819) have high mean forage dm yield but less stable when compared to the standard check. table 4. forage dry matter, crude protein, and in vitro organic matter digestible yields advantage of napier grass varieties over the standard check. variety dm yield % increase cp yield % increase ivomd yield % increase 16791 13.0 62.5 0.79 71.7 6.63 66.6 15743 9.8 22.5 0.57 23.9 5.02 26.1 16819 8.9 11.3 0.54 17.4 4.56 14.6 ilri-16984 (standard check) 8.0 – 0.46 – 3.98 – note: dm = dry matter; cp = crude protein; and ivomd = in vitro organic matter digestibility. 5. reaction to diseases and pests the varieties (16791, 15743, 16819, and standard check) were tested for their diseases and pests reaction starting from the initial stage of evaluation to verification stage and found to be resistant/moderately resistant to major diseases which can affect the varieties (figure 2). the diseases' effect on the performance of napier grass varieties were recorded as 0-10% resistant, 11-30% moderately resistant, 31-60% moderately susceptible, and 61100% susceptible. accordingly, the released varieties (zehone-02 and zehone-03) were found to be resistant to the recorded major diseases (rust, and root rot diseases) as compared to the standard check variety and other candidate variety during the experimental periods. generally, no pests’ problem was recorded during the experimental periods. the resistance reaction of the varieties could be integrated with other diseases management strategies for better results. 0 2 4 6 8 10 12 14 16 holetta debrezeit hawassa d ry m at te r y ie ld t / h a locations 16791 15743 16819 gezahegn et al. east african journal of sciences volume 15(2): 183-190 188 figure 2. overall mean response of napier grass varieties for rust and root rot diseases. 6. quality attributes the chemical compositions and in vitro organic matter digestibility of napier grass varieties are presented in table 5. the ash content of the candidate napier grass varieties showed a difference, ranging from 133.7 to 149.5 g kg–1 dm. high ash contents in forage plants could be an indication of high mineral concentration. the concentration of minerals in forage varies due to factors like plant developmental stage, morphological fractions, climatic conditions, soil characteristics, and fertilization regime. the crude protein (cp) content of the candidate varieties ranged from 57.7 to 60.5 g kg– 1 dm. under high temperatures in the tropics, there is rapid growth and development of grasses resulting in a high rate of decline in the proportion of leaves than stems, which reduce cp content and digestibility. the in vitro organic matter digestibility (ivomd) content of the tested candidate varieties ranged from 510.3 to 512.0 g kg–1 dm. the decline in digestibility as napier grass matured may be attributed to the observed declines in cp content, and an increase in detergent fibers and degree of lignification. the neutral detergent fiber (ndf) content ranged from 728.5 to 778.4 g kg–1 dm. the decline in digestibility may, therefore, have been mainly due to the fiber chemistry and anatomical structure of the cell wall rather than its content. the candidate varieties had advantages over the standard check variety in terms of leaf to stem ratio, cp, and ivomd (table 6). the result showed that zehone-03 variety had the highest leaf to stem ratio (23.2%) advantage followed by zehone-02 (17.9%) and 15743 (16.8%) over the standard check. similarly, zehone-03 and zehone-02 varieties had the same highest cp (6.0%) content while zehone-03 and 15743 varieties had the same highest ivomd (2.9%) content advantages over the standard check. table 5. chemical compositions and in vitro organic matter digestibility of napier grass varieties. variety dm (g kg–1) ash cp ndf adf adl ivomd 16791 149.5 60.5 778.4 492.8 67.3 510.3 15743 133.7 57.7 767.7 479.5 66.6 512.0 16819 147.9 60.5 728.5 461.4 67.2 512.0 ilri-16984 (standard check) 149.4 57.1 785.5 464.0 85.1 497.4 note: dm = dry matter; cp = crude protein; ndf = neutral detergent fiber; adf = acid detergent fiber; adl = acid detergent lignin; and ivomd = in vitro organic matter digestibility. table 6. leaf to stem ratio, crude protein, and in vitro organic matter digestibility advantages of napier grass varieties over the standard check. variety lsr % increase cp % increase ivomd % increase 16791 1.12 17.9 60.5 6.0 510.3 2.6 15743 1.11 16.8 57.7 1.1 512.0 2.9 16819 1.17 23.2 60.5 6.0 512.0 2.9 ilri-16984 (standard check) 0.95 – 57.1 – 497.4 – note: lsr = leaf to stem ratio; cp = crude protein; and ivomd = in vitro organic matter digestibility. 0 1 2 3 4 5 6 7 16791 15743 16819 ilri-16984 d is e as e i n c id e n c e ( % ) variety rust root rot gezahegn et al. registration of napier grass 189 7. adaptation the released napier grass varieties, zehone-02 (16791) and zehone-03 (16819), are adapted to mid and high-altitude areas of the country. the varieties performed very well in areas with altitudes ranging from 1500 to 2500 meters above sea level, which have an annual rainfall of 700 to 1200 mm. it could also be possible to extend the production of both varieties to other areas with similar agro-ecologies after doing adaptation trials. both varieties produce higher dry matter yield when recommended fertilizers are applied at the appropriate rates. for better performance, the varieties should be planted in mid-june to mid-july under rain-fed conditions and any time when irrigation water is available. the released varieties have fast growth and better forage dry matter yield performances in the mid-altitude areas when compared to high altitude areas of the country. 8. conclusion the new napier grass varieties performed differently in terms of agronomic performance, yield stability, and nutritive values across the test environments. this may be attributed to variations in edaphic, climatic, and biotic factors across the locations. measured agronomic traits such as tillering performance, plant height, leaf to stem ratio, forage dm yield showed variations among the tested varieties and the environments. the varieties also showed variations in forage dm yield stability across the test environments during the experimental periods. different stability parameters and models indicating that the standard check (ilri-16984) variety is considered more stable when compared to other varieties evaluated in the study. on the other hand, varieties such as zehone-02 and zehone-03 were found to be less stable varieties across the test environments but gave better dm yield performance. the crude protein (cp) and in vitro organic matter digestibility (ivomd) were higher in the high-altitude area while cp yield, digestible yield, and most fiber components were relatively higher in the mid-altitude areas indicating that temperature and amount of rainfall and its distribution hurt the feed quality of napier grass varieties. generally, zehone-02 and zehone-03 varieties have better mean dm yield performance but less stable when compared to other varieties included in the study. therefore, zehone-02 (16791) variety was released for its better forage dm yield while zehone-03 (16819) variety for its thinstemmed stature, which could be considered as different merit, which varies, from the candidate varieties and other varieties released so far. generally, thin-stem varieties have better nutritional qualities and conserved as hay when compared to bold-stem varieties. however, bold-stem varieties can be conserved in the form of silage for efficient utilization. therefore, both napier grass varieties (zehone-02 and zehone-03) have been released in 2017 for production in the mid and high-altitude areas and similar agroecologies in the country. the planting materials of both napier grass varieties are maintained by the feed and nutrition research section of holetta agricultural research center. 9. acknowledgements the authors acknowledge the ethiopian institute of agricultural research for funding the research; staff of feeds and nutrition research program working in the respective research centers for their smooth implementation of the experiment over years; animal nutrition research staff of holetta agricultural research center for assisting in laboratory analyses. 10. references alemayehu mengistu. 1997. conservation based forage development for ethiopia. self help development international and institute for sustainable development. berhanena selam printing press, addis ababa, ethiopia. pp. 197. clayton, w.d., govaerts, r., harman, k.t., williamson, h. and vorontsova, m. 2013. world checklist of poaceae. royal botanic gardens, kew, richmond, uk. eberhart, s.a. and russell, w.a. 1966. stability parameters for comparing varieties. crop science, 6: 36–40. farrell, g., simons, s.a. and hillocks, r.j. 2002. pests, diseases and weeds of napier grass, pennisetum purpureum: a review. journal of pest management, 48(1): 39–48. fekede feyissa, getnet assefa, lulseged g/hiwot, muluneh minta and tadesse tekletsadik. 2005. evaluation of napier grass-vetch mixture to improve total herbage yield in the central highlands. proceedings of the 13th annual conference of the ethiopian society of animal production (esap), august 25–26, 2005, addis ababa, ethiopia. finlay, k.w. and wilkinson, g.n. 1963. the analysis of adaptation in a plant breeding program. australian journal of agricultural research, 14: 742–754. getnet assefa and gezahagn kebede. 2012. seed research and development of perennial forage crops in the central highlands. pp. 95– 109. in: getnet assefa, mesfin dejene, jean hanson, getachew anemut, solomon mengistu, and alemayehu mengistu (eds.). forage seed research and development in ethiopia. proceedings of workshop held on 12–14 may, 2011 at eiar, addis ababa, ethiopia. gezahagn kebede, fekede feyissa, getnet assefa, mengistu alemayehu, alemayehu mengistu, et al. 2017. agronomic performance, dry matter yield stability and herbage quality of napier grass (pennisetum purpureum (l.) schumach) accessions in different agro-ecological zones of gezahegn et al. east african journal of sciences volume 15(2): 183-190 190 ethiopia. journal of agricultural and crop research, 5(4): 49–65. lowe, a.j., thorpe, w., teale, a. and hanson, j. 2003. characterization of germplasm accessions of napier grass (pennisetum purpureum and p. purpureum x p. glaucum hybrids) and comparison with farm clones using rapd. genetic resources and crop evolution, 50: 121–137. moa (ministry of agriculture). 2017. crop variety register. issue no 20, 2017. addis ababa, ethiopia. mwendia, s.w., wanyoike, m., nguguna, j.g.m., wahome, r.g. and mwangi, d.m. 2006. evaluation of napier grass cultivars for resistance to napier head smut. proceedings of the 10th kari biennial scientific conference, kari, nairobi, kenya. pp. 85–97. seyoum bediye, zinash shelishi, tadesse tekletsadik and liyusew ayalew. 1998. evaluation of napier grass (pennisetum purpureum) and pennisetum hybrids (pennisetum purpureum x pennisetum typhoides) in the central highlands of ethiopia. proceedings of the 5th national conference of ethiopian society of animal production. 15–17 may, 1997, addis ababa, ethiopia. tessema zewdu. 1999. napier grass adapts well in north western ethiopia. agritopia, earo 14(1), january–march 1999. tessema zewdu. 2005. variation in growth, yield, chemical composition and in-vitro dry matter digestibility of napier grass varieties (pennisetum purpureum). tropical sciences, 45: 67–73. tessema zewdu. 2008. effect of plant density on morphological characteristics, yield and chemical composition of napier grass (pennisetum purpureum (l.) schumach). east african journal of sciences, 2: 55–61. tudsri, s., jorgensen, s.t., riddach, p. and pookpakdi, a. 2002. effect of cutting height and dry season date on yield and quality of five napier grass cultivars in thailand. tropical grassland, 36: 248–252. ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15 (1) 51-60 licensed under a creative commons *corresponding author: murt.stat@gmail.com attribution-noncommercial 4.0 international license. short-run and long-run relationships between economic growth, inflation, exchange rate and remittance in ethiopia: application of vector error correction model approach murad mohammed1* and beyan ahmed2 1department of statistics, haramaya university, p.o. box 138, dire dawa, ethiopia 2school of agricultural economics and agribusiness, haramaya university, p.o. box 138, dire dawa, ethiopia abstract background: economic growth is the central aim of countries worldwide. sustaining economic growth is among the main challenges in ethiopia. this could be attributable to the fluctuations in domestic inflation and exchange rate. objective: the objective of this study was to analyze the short-run and long-run relationships between economic growth, inflation, exchange rate and remittance in ethiopia. materials and methods: the yearly time series data from 1990 to 2020 (30 years) was used. the augmented dickey fuller (adf) and phillips-perron (pp) tests of unit root were employed to examine whether the series became stationary or not at level. the johanson co-integration test was performed to determine the co-integration of the variables in the long-term. after stationarity and integration tests were performed, the vector error correction model (vecm) was employed to estimate the model. results: the trace statistic and the maximum eigen-value test of co-integration showed that at least one co-integrating vector (r>1) exists in the system at 0.05 level of significance. the results provided that for economic growth, the system corrects its previous period disequilibrium at the speed of 27.34% yearly in the long-run. for inflation rate, exchange rate and remittance, the system corrects its previous period disequilibrium at a speed of 3.58%, 5.38% and 9.84% yearly in the long-run, respectively. economic growth was negatively affected by inflation rate and positively affected by remittance in the shot-run. inflation rate was negatively affected by remittance in the short-run. the exchange rate was negatively affected by economic growth and inflation and remittance was negatively affected by economic growth in the short-run. conclusion: the short-run changes in inflation and remittance had a strong and significant effect on the changing economic growth in the long-run. the study recommended that a monetary policy be formulated with the objective of achieving and maintaining price stability, as opening the market for receiving remittance through increasing investment and human capital and to ensure inflation rate stability as well as enhance local production and export trade. keywords: co-integration; long run; short run; stationarity; vector error correction 1. introduction economic growth is the main target for countries all over the world. among other things, gross domestic product (gdp) increment is a good indicator of economic growth; higher gdp implies higher income and better standard of living. one of the important ingredients of gdp is saving. therefore, most efforts to increase gdp and economic growth rely on savings (karen and louise, 2018). for various developing countries including ethiopia, the inflow of remittance shows increment and imperative rising of gdp, which has a building effect on the economy. according to the data of world bank, from the entire remittance the country received in the previous three decades, more than 87% of the inflow was gained in the last two decades (ratha, 2016). while the emerging economies increased, the general inflow of foreign direct investment (fdi) declined the inflow of remittance remained increasing and sustaining the people’s livelihood via reducing poverty and meeting their demands (tassew and nandeeswar, 2016). remittance has increased in ethiopia which constitute 300 billion dollars in 2007, 538 million dollars in 2011, 833 million dollars in 2013 and its increased to 1,796 million dollars in 2014 and 1,087 million dollars in 2015 while its decline to 393 million dollars in 2017 and raised to 531 million dollars in 2019 (wb, 2015). there are different contradictory perspectives regarding the impact of remittance on economic growth. these are optimists (with a view that mailto:murt.stat@gmail.com murad and beyan east african journal of sciences volume 15 (1) 51-60 52 remittances have a positive effect on economic growth for the countries receiving remit through increasing investment and human capital) and pessimists (remittances negatively affect economic growth through inflation and moral hazards resulting from reduced labor supply) (haas, 2007; tassew and nandeeswar, 2016). the study done by jemma et al, (2019) found that remittance affects economic growth positively (increment in remittance would increase foreign investment thus, gdp should increase) and on the other hand, the remittance affects the economic growth negatively in long-run (increase in remittance increase domestic inflation so that gdp would decline) (tassew and nandeeswar, 2016). a stable long-term economic growth requires stable trade and foreign exchange markets to ensure a stable exchange rate system and favorable terms of trade. different papers present the relationship of exchange rate and economic growth in different ways; razzaque et al. (2017) found that the exchange rate affects economic growth negatively in the long-run and in the short-run in bangladesh. correspondingly, kogid et al. (2012) found that both exchange rates, nominal and real, are considered to have positive effects on economic growth. the study adopted autoregressive distributed lag by using the data from 1971-2009. as reported in the study undertaken in ethiopia, real effective exchange rates, broad money supply and trade openness have a positive impact on economic growth in the long-run (nigussie, 2016). similarly, the real effective exchange rate has a positive effect on economic growth in short-run through depreciation in the value of the domestic currency and it has negative effect on economic growth in the long-run (fentahun, 2011). in developing countries like ethiopia, double digit inflation has become problematic for policy makers as well as the society. emrta (2013) found the optimal level of inflation in ethiopia around which inflation affect economic growth optimally. the study has applied threshold approach. by doing so on the data from 1971-2010, inflation level of about 10% is optimal for ethiopia. the most important approach that claims the existence of a positive relationship between inflation and growth is the phillips curve approach. this approach assumed that a high inflation causes low rates of unemployment thereby affect economic growth positively (emrta, 2013). according to the annual report of national bank of ethiopia, the annual average headline inflation at the end of the fiscal year 2019/20 was rose to 19.9 percent from 12.6 percent a year ago. this was largely owing to 10.2 percent rise in food & non-alcoholic beverages inflation from 13.1 percent to 23.3 percent and 3.9 percent increase in non-food inflation from 11.9 to 15.8 percent (nbe, 2019/20). in general, the overall inflation has increased by 13.6 percent in november 2017 as compared to the one observed in november 2016. the food inflation has increased by 18.1 percent in november 2017 as compared to the one observed in november 2016. the non-food inflation also increased i.e. by 8.6 percent in november 2017 as compared to the one observed in november 2016 (rajesh, 2018). inflation undermines the confidence of domestic and foreign investors about the future route of monetary policy (international monetary fund, 2019). some researchers have studied the linkage between inflation and economic growth using different approaches. there exists a positive relationship between inflation and economic growth in ethiopia (demile, 2015). another study confirmed that the linkages between inflation and economic growth are negative (yabu and kessy, 2015; mamo, 2012). tadele (2014) found that the relationship between inflation and economic growth was positive in ethiopia in the long-run and short-run; but for uganda there is negative relationships between inflation and growth. wambui (2013) found a positive relationship between inflation and economic growth in kenya. this study was intended to examine the relationships between inflation, exchange rate, remittance and economic growth in the shortand long-run. it also assessed the extent to which inflation, exchange rate and remittance affect economic growth in ethiopia. accordingly, the main objective of this study is to see the shortand long-run relationship between economic growth, inflation, exchange rate and remittance in ethiopia by employing 30-year time series data and using econometric analysis. 2. material and methods 2.1. data source the study employed the yearly data from 1990 to 2020 to determine the short-run dynamics and long-run relationship between economic growth, inflation, exchange rate, and remittance in ethiopia. the data on gdp in us dollar was obtained from the international monetary fund (imf) and the world economic outlook databases. data on remittance in us dollar, inflation and exchange rate were extracted from world bank database. 2.2. econometric model specification the stationarity test of the time series data can be determined by applying the unit root test such as augmented dickey-fuller (adf) test, philips peron (pp) test, kwiatkowski–phillips–schmidt–shin (kpss) tests, adf-gls test and soon. among these unit root tests, in this study augmented dickey-fuller (adf) test and philips peron (pp) test were applied. a time series data is said to be stationary when its mean and variance are similar over the given time and the covariance that exists between the two variables was invariant in the observed time. murad and beyan economic growth, inflation, exchange rate and remittance in ethiopia 53 2.2.1. the augmented dickey–fuller (adf) test the adf test builds a parametric adjustment for higher order correction by assuming that the series y𝑡 follows autoregressive, ar(p) process with order of lag p (dickey and fuller, 1979). thus, the test has been done adding p lagged difference terms of the dependent variable as an independent variable on the right-hand side of the test regression. the adf test estimating the following regression:  = −− ++++= p 1i titi1t21t εδyαytββδy  (1) where, β1, β2, δ and α are coefficients, t is the stochastic time-trend, ℇt is a white noise error term and ,yyδy,yyδy 3t2t2t2t1t1t −−−−−− −=−= etc. 2.2.2. philips peron (pp) tests the phillips-perron test is an alternative technique for unit root tests which ignores any serial correlation in the error-term without adding lagged difference terms and they use the standard df or adf test but adjust the t-ratio so that the serial correlation does not affect the asymptotic distribution of the test statistic. 2.2.3. co-integration test in the entirely particular regression model ttt εβxy += , there is a presumption that the disturbances tε are stationary, white noise series. but this presumption is unlikely to be true if ty and tx are integrated series. generally, if two series are integrated to different orders, then linear combinations of them will be integrated to the higher of the two orders. if ty and tx are each drifting upward with their own trend, then unless there is some relationship between those trends, the difference between them should also be growing, with yet another trend. there must be some kind of inconsistency in the model. intuitively, if the two series are both ( )1i , then the difference between them might be stable around a fixed mean. the implication would be that the series are drifting together at roughly the same rate. two series that satisfy this requirement are said to be co-integrated vector. in such a case, it can be differentiated between a long-run relationship between ty and tx that is, the manner in which the two variables drift upward together, and the short-run dynamics, that is, the relationship between deviations of t y from its longrun trend and deviations of t x from its long-run trend. if this is the case, then differencing the data would be counterproductive, since it would obscure the long-run relationship between ty and tx . studies of co-integration and a related technique, error correction, are concerned with methods of estimation that preserve the information about both forms of covariation. 2.2.4. vector error correction model (vecm) the vector autoregressive (var) model is a common framework used to express the dynamic interrelationship among stationary variables. so, the first step in time series analysis should be to decide whether the levels of the data are stationary. if not stationary, take the first differences of the series and try again. if the time series are not stationary at level, then the var framework needs to be modified to allow consistent estimation of the relationships among the series. the vector error correction model (vecm) is just a special case of the var for variables that are stationary in their differences (i.e., i(1)). if the series are co-integrated, the series move together in the long-run. a var of the first differences does not capture the long-run relationship. therefore, it is appropriate to use vecm rather than var in order to reveal the short and long-term tendencies between the series. the vecm can also take into account any co-integrating relationships among the variables. consider a var with p lags tptp2t21t1t εya......yayaby +++++= −−− (2) where, ty a kx1 vector of variables, b is kx1 vector of parameters, p1 a....a are kxk matrix of parameters and t is kx1 vector of disturbances. the vec model is specified as follows:  − = −− +++= 1p 1i titi1tt εδyγπybδy here,  = +−= p 1i in aiπ , (3) and n i is an identity matrix, a’s are kxk matrix of parameters. specifically, when we use our variables the vecm can be specified as follows: murad and beyan east african journal of sciences volume 15 (1) 51-60 54 )4(εecηδremαδexrαδinrαδgdpααδgdp 1p 1j t11t1 1p 1l 1tl5 1p 1k 1tk41tj3 1p 1i 1ti21t   − = − − = − − = −− − = − ++++++= )5(εecηδremβδexrβδinrβδgdpββδinr 1p 1j t21t2 1p 1l 1tl5 1p 1k 1tk41tj3 1p 1i 1ti21t   − = − − = − − = −− − = − ++++++= )6(εecηδremθδexrθδinrθδgdpθθδexr 1p 1j t31t3 1p 1l 1tl5 1p 1k 1tk41tj3 1p 1i 1ti21t   − = − − = − − = −− − = − ++++++=   − = − − = − − = −− − = − ++++++= 1p 1j t41t4 1p 1l 1tl5 1p 1k 1tk41tj3 1p 1i 1ti21t )7(εecηδremγδexrγδinrγδgdpγγδrem  where, tδgdp is the difference of economic growth at time t, tδinr is the difference of inflation rate at time t, t δexr is the difference of exchange rate at time t, tδrem is the difference of remittance at time t, ec is the error correction term which is the estimated residual from the co-integration regression and tε is the random disturbance term at time t. here, gross domestic product is the major indicator of ethiopian economic growth. therefore, the study tried to find the short-run dynamics and long-run relationship between economic growth and other macroeconomic variables considered. 3. results and discussion 3.1. descriptive statistics to accomplish the research objectives, the yearly data span from 1990 to 2020 in ethiopia was investigated. in this study, different econometric models were employed to analyze the relationship between gross domestic product (proxy for economic growth) and inflation, exchange rate and remittance. some descriptive statistics including mean, standard deviation, minimum and maximum values of the series under study were computed (table 1). the result presented that the average gross domestic product covering the year from 1990 to 2020 in ethiopia was 30.54 billion dollars whereas the minimum and maximum values were 6.92 billion dollars and 95.91 billion dollars over 31 years, respectively. the reason for the minimum gdp was that, ethiopia experienced political instability, poverty and drought. furthermore, the average inflation rate was 10.98% and exchange rate was 12.62 dollars over the year from 1990 to 2020. on average, the remittance over 31 years was 0.315 million dollars whereas the minimum and maximum remit money from abroad were 0.005 million dollars and 1.796 million dollars, respectively. table 1. descriptive statistics. variables obs mean std. dev. min max gdp in billion dollars 31 30.544 29.353 6.928 95.91 inflation rate 31 10.979 11.378 -8.484 44.391 exchange rate 31 12.619 8.843 2.07 33.25 remittance in million dollars 31 0.315 0.400 0.005 1.796 note: gdp = gross domestic product, obs = observations, std.dev. = standard deviation, min = minimum value, and max = maximum value. the trends of the selected macroeconomic variables were displayed as shown in figure 1 and suggested that the series of all the variables were non-stationary at their level and shows increasing trend except inflation rate and remittance. murad and beyan economic growth, inflation, exchange rate and remittance in ethiopia 55 figure 1. plots of economic growth, inflate rate, exchange rate and remittance. 3.2. unit root test the time series under contemplation should be checked for stationary before one can endeavor to fit an appropriate model. that is, the variables have to be tested for the presence of unit root(s) thereby the order of integration of each series was determined. the stationarity of the series was tested by using an augmented dickey-fuller test and a phillips and perron test. the results of adf and pp tests, with constant and trend both at level and first difference for each series were presented in table 2. the results indicated that the null hypothesis that the series in levels contain unit root could be accepted for all series. that is, the respective p-values were greater than conventional significance levels α = 0.05 and 0.01. since the null hypothesis cannot be rejected, in order to determine the order of integration of the nonstationary time series, the same tests were applied to their first differences. the order of integration is the number of unit roots that should be contained in the series so as to be stationary. this implies that all variables were stationary at first difference i(1), hence proving argument sustained for further estimating the long-run relationship. table 2. unit root test results. variable adf test pp test at level at first difference at level at first difference pvalue pvalue pvalue pvalue gdp 1.76 0.000 -0.16 0.000 inflation rate 1.93 0.000 -0.76 0.000 exchange rate 0.68 0.000 -1.39 0.000 remittance -1.54 0.000 -2.03 0.000 note: adf is augmented dickey-fuller test and pp is phillips and perron test. 3.3. co-integration analysis it was possible to proceed for co-integration test since the variables were integrated of order one. the existence of potential short-run dynamics and long-run equilibriums among the variables in the model was determined using the co-integration test. test of johansen (1992) co-integration was applied to the variables under study to test for co-integration based on the trace statistic test and maximum egien-value test. the trace tests and maximum eigen-value test were made consecutively based on the first hypothesis of no co-integration to a rising number of co-integrating vectors. the results of co-integration tests for economic growth, inflation, exchange rate and remittance were described in table 3. results of cointegration test revealed that the trace statistic and the maximum eigen-value test indicated that at least one co-integrating vectors (r>1) exists in the system at the 95% confidence level. the result was consistent with that of dufera and desa (2020). murad and beyan east african journal of sciences volume 15 (1) 51-60 56 table 3. co-integration test results. hypothesis trace statistic maximum eigenvalue h0 h1 trace statistic 5% critical value p-value max-eigen value 5% critical value p-value r ≤ 0 r > 0 59.4569 48.8743 0.0033 31.3564 28.5843 0.0054 r ≤ 1 r > 1 30.2546* 29.7854 0.0512 20.5532* 21.1316 0.0636 r ≤ 2 r > 2 8.6963 15.5479 0.3654 8.5769 14.2654 0.4258 r ≤ 3 r > 3 0.0864 3.8698 0.9810 0.0985 3.8415 0.9562 note: * denotes rejection of null hypothesis at 5% level of significance. ho: there is no co-integration among variables h1: there is cointegration. decision: reject the null hypothesis (ho) which was no co-integration among variables and therefore, it can be concluded that there is co-integration among variables. from the johansen co-integration test, it was determined that the rank of co-integration matrix to be equal to one. consequently (table 5), the co-integrating vector is given by β= (1, -1.62584, 1.52529, -1.26247). the values correspond to the co-integrating coefficients of gdp (normalized to one), inflation, exchange rate and remittance, respectively. thus, the vector above can be expressed as follows: ttt1 rem262471.exr1.52529inr1.62584gdpcte −+−= − where, ect is error correction term, inr is inflation rate, exr is exchange rate, and rem is remittance. 3.4. lag length selection results preferring an appropriate lag length had strong inferences for successive modeling. choosing too few lags could result in systematic variation in the residuals whereas if too many lags were selected, it came with the penalty of fewer degrees of freedom. the likelihood ratio (lr), akaike information criterion (aic), bayes information criterion (bic), and hannan-quin information criteria (hqic) were used to determining a suitable lag length (table 4). lag two was selected to be the appropriate lag length, as these were selected by the majority of the criterion. table 4. lag selection criteria for co integration. lag ll lr df p fpe aic hqic bic 0 -65.73 .000804 4.23 4.28688 4.40724 1 92.03 315.52 16 0.000 1.5e-07 -4.37 -4.06 -3.46* 2 138.24 51.19* 16 0.000 7.6e-08* -5.23* -4.43* -2.87 3 112.64 41.22 16 0.001 1.2e-07 -4.64 -4.09 -3.01 4 149.57 22.66 16 0.123 1.3e-07 -4.94 -3.91 -1.86 note: ll is lag length, lr is likelihood ratio, df is degrees of freedom, p is probability, fpe is final prediction error, aic is akaike information criterion, hqic is hannan-quinn information criterion, bic is bayes information criterion, and *indicates lag order selected by the criterion. 3.5. vector error correction model (vecm) estimation co-integration and non-spurious regression were the basic requirements of vecm. there was adequate substantiation on the long-run relationship between the variables under consideration according to the results of co-integration test (table 3) as there was a cointegration relationship. result of adf and pp tests provides adequate verification of stationarity of the variables (table 2) at first difference. since the series were co-integrated and non-spurious, it was possible to estimate vec model. the estimation results of vecm given in (table 5). murad and beyan economic growth, inflation, exchange rate and remittance in ethiopia 57 table 5. vector error correction model estimation results. variable coef. std. err. z-stat p-value t δgdp 1-t ec -0.27345 0.11911 2.295 0.000* 1t δgdp − 0.32728 0.19459 1.681 0.193 1t δinr − -0.10834 0.03344 -3.239 0.003* 1t δexr − -1.53016 0.25902 -5.907 0.536 1t δrem − 0.43237 0.36947 1.170 0.001* _cons 0.51481 0.39018 1.319 0.187 t δinr 1-t ec -0.03582 0.01645 -2.177 0.000* 1t δgdp − 3.03171 0.85604 3.541 0.089 1t δinr − -0.12970 0.21557 -0.602 0.885 1t δexr − 5.64983 0.61595 9.172 0.100 1t δrem − -5.13618 0.82301 -6.240 0.002* _cons 0.24039 0.39818 0.603 0.920 t δexr 1-t ec -0.05382 0.20653 -0.261 0.003* 1t δgdp − -0.18448 0.05638 -3.240 0.005* 1t δinr − -0.13703 0.11003 -1.245 0.000* 1t δexr − 0.51876 0.16768 3.093 0.132 1t δrem − 0.27442 0.20081 1.366 0.172 _cons 0.16066 0.11703 1.372 0.170 t δrem 1-t ec -0.09845 0.04658 -2.113 0.000* 1t δgdp − -0.10587 0.04617 -2.293 0.001* 1t δinr − -0.63225 0.49693 -1.272 0.432 1t δexr − 0.05531 0.13264 0.416 0.677 1t δrem − -0.36933 0.15885 -2.325 0.000* _cons 0.069226 0.09258 0.747 0.455 note: ec = error correction, gdp = gross domestic product, inr = inflation rate, exr = exchange rate, rem = remittance, _cons = constant value, coef = coefficients, std.err. = standard error, z-stat = z-statistic, and * indicates that significance level at 5% level of significant. normalization form of co-integrating coefficients (p-values in parentheses) gdp inr exr rem 1.00 -1.625842 1.52529 -1.26247 (0.000) (0.016) (0.008) murad and beyan east african journal of sciences volume 15 (1) 51-60 58 the vecm estimates indicated that in the economic growth (δgdp) equation, the lagged error correction (ec) term was negative and significant at 5% level meaning that the system corrects its previous period disequilibrium at a speed of 27.34% yearly. it implied that the model identified the substantial speed of adjustment by 27.34% of disequilibrium correction yearly for reaching long-run equilibrium steady state position. the coefficient of the lagged ec term for inflation rate ( 2 η = -0.03582, p= 0.000) was negative and significant meaning that the system corrects its previous period disequilibrium at a speed of 3.58% yearly. the coefficient of the lagged ec term for exchange rate ( 3 η = -0.05382, p=0.003) was negatively significant at 5% level indicating that system corrects its previous period disequilibrium at a speed of 5.38% yearly and the coefficient of lagged ec term for remittance ( 4 η = -0.09845, p=0.000) were negative and significant at 5% level implying that the system corrects its previous period disequilibrium at a speed of 9.84% yearly. this result was inconsistent with the finding of abis (2014). as indicated in table 5, the short-run dynamics were hold throughout the individual coefficients of the difference terms. the examination of the short-run relationship between the variables confirmed that economic growth was negatively affected by the first lag of inflation rate and positively affected by the first lag of remittance in shot-run. in this equation, the short-run coefficients of first lag of exchange rate and past values of gdp were insignificantly different from zero. this implies that the values of exchange rate and previous values of economic growth had no short-run effects on the economic growth. this result is consistent with some other studies (jemma et al, 2019; mamo, 2012; yabu and kessy, 2015). in the inflation rate regression, the effects of the first lag of remittance were negatively significant, but the other short-run coefficients in this equation were insignificantly different from zero. this implied that inflation was negatively affected by remittance in ethiopia, but gdp and exchange rate had no short-run effects on inflation. this result was in contrast with the finding by gizaw (2016), but similar with the finding of lim and sek (2015). for the exchange rate equation, the short-run coefficient of the first lag of gdp and first lag of inflation rate were negatively significant, but the shortrun coefficients of remittance were insignificantly different from zero. this implied that remittance had no short-run impact on exchange rate. this result is inconsistent with the finding of fentahun (2011) who found that the real effective exchange rate had a positive effect on economic growth in the short-run. in the remittance regression, the effects of the first lag of gdp and its own past values were negatively significant and the other coefficients were insignificantly different from zero. this implied that economic growth of previous year negatively affected the remittance in the short-run. furthermore, values of remittance in previous years inversely affected the current values of remittance. thus, as economic growth of previous year was raised, the demand of people for remitting money from abroad in the current year was decreased. but, inflation and exchange rate had no relationships with remittance in the short-run. 4. conclusion and recommendations the main objective of this study was to analysis the short-run and long-run relationships between inflation, remittance, exchange rate and economic growth in ethiopia. the study used the world bank’s and international monetary fund databases spanning from 1990 to 2020 periods as sources of data or information. the study employed vector error correction model data analysis methods. economic growth, inflation, exchange rate and remittance were stationary at first difference and there is at least one co-integration between them. the results of the study showed that the system corrects its past period disequilibrium at a specified speed of adjustment in long-run for economic growth, inflation, exchange rate and remittance. the inflation rate and remittance had strong impacts on economic growth in the short run. furthermore, remittance affects inflation negatively in the short-run while gdp and inflation rate have strong impact on exchange rate in the short-run. economic growth strongly and negatively affected remittance in the shortrun. however, exchange rate had no short-run effect on gdp while gdp and exchange rate had no impacts on inflation in the short-run. the results also indicated that in a case of shock and disequilibrium, the model converges to its equilibrium position in the long-run. the estimated results revealed that 27.34% of the disequilibrium in economic growth adjusted each year. based on the finding of this study, it is recommended that a monetary policy be formulated with the objective of achieving and maintaining price stability, as opening the market for receiving remittance through increasing investment and human capital and to ensure inflation rate stability as well as enhance local production and export trade. in addition, the implication of a holistic program of economic reform is essential to complement the inflation rate and remittance policy to encourage economic growth. 5. acknowledgements the authors express sincere gratitude to all colleagues working at haramaya university for giving constructive idea for the success of this study. murad and beyan economic growth, inflation, exchange rate and remittance in ethiopia 59 6. references abis, g.m. 2014. the relationship between inflation and economic growth in ethiopia. university of south africa, pretoria. available on: http://hdl.handle.net/10500/13633. demile, a. 2015. inflation-growth nexus in ethiopia: evidence from threshold auto regressive model. ethiopian journal of economics, 24(1): 1–30. dickey, d.a. and fuller, w.a. 1979. distribution of the estimators for auto-regressive time series with a unit root. journal of the american statistical association, 74: 427–431. dufera, t. and desa, d. 2020. econometric analysis of retail prices of major agricultural food commodities in dire dawa city administration, ethiopia. world journal of agricultural research, 8(1): 6–11. emrta, a. 2013. inflation and economic growth: an estimate of the threshold level of inflation for ethiopia. ethiopian economic association, addis ababa, ethiopia. fentahun, b. 2011. the impact of real effective exchange rate on the economic growth of ethiopia. ma thesis, addis ababa university, ethiopia. pp. 21–34. gizaw, b.t. 2016. an empirical investigation on the relationship between inflation and economic growth in ethiopia. addis ababa, ethiopia. available on: http://repository.smuc.edu.et/handle/12345678 9/1260. jemma, d., tunc, g., hector, p.s. and mounir, b. 2019. the impact of remittances on economic activity: the importance of sectoral linkages. imf working papers, avaliable on: https://www.imf.org/en/publications/wp/iss ues/2019/08/16/the-impact-of-remittanceson-economic-activity-the-importance-ofsectoral-linkages-47091. johansen, s. 1992. a representation of vector autoregressive processes integrated of order 2. econometric theory, 8(2): 188–202. karen, d. and louise, s. 2018. gdp as a measure of economic well-being. hutchins center working paper #43, available on: https://www.brookings.edu/wpcontent/uploads/2018/08/wp43-8.23.18.pdf. kogid, m., asid, r., lily, j., mulok, d. and loganathan, n. 2012. the effect of exchange rates on economic growth: empirical testing on nominal versus real. iup journal of financial economics, 10(1): 1–13. lim, y.c. and sek, s.k. 2015. an examination on the 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outlook. the world bank, washington, dc. available at https://doi.org/10.1596/978-1-4648-09132. razzaque, m. a., bidisha, s. h. and khondker, b. h. 2017. exchange rate and economic growth: an empirical assessment for bangladesh. journal of south asian development, 12(1): 42–64. tassew, d. and nandeeswar, r. 2016. the impact of remittances on economic growth in ethiopia. indian journal of commerce and management studies, 7(2): 01–15. tadele, a. 2014. inflation and growth relationships: a comparative study of ethiopia and uganda, addis ababa, ethiopia. available on: http://localhost:80/xmlui/handle/123456789/3 020. wambui, v.t. 2013. effects of government expenditure, taxes and inflation on economic growth in kenya: a disaggregated time series analysis. university of nairobi. available at http://erepository.uonbi.ac.ke:8080/xmlui/han dle/123456789/58657. wb (world bank). 2015. migration and remittances: recent developments and outlook. migration and development brief 24. world bank. pp. 27. international monetary fund. 2019. world economic outlook: global manufacturing downturn, rising trade barriers. washington dc. pp. 2018. yabu, n. and kessy, n.j. 2015. appropriate threshold level of inflation for economic growth: evidence from the three founding eac countries. applied economics and finance, 2(3): 127–144. http://hdl.handle.net/10500/13633 http://repository.smuc.edu.et/handle/123456789/1260 http://repository.smuc.edu.et/handle/123456789/1260 https://www.imf.org/en/publications/wp/issues/2019/08/16/the-impact-of-remittances-on-economic-activity-the-importance-of-sectoral-linkages-47091 https://www.imf.org/en/publications/wp/issues/2019/08/16/the-impact-of-remittances-on-economic-activity-the-importance-of-sectoral-linkages-47091 https://www.imf.org/en/publications/wp/issues/2019/08/16/the-impact-of-remittances-on-economic-activity-the-importance-of-sectoral-linkages-47091 https://www.imf.org/en/publications/wp/issues/2019/08/16/the-impact-of-remittances-on-economic-activity-the-importance-of-sectoral-linkages-47091 https://www.brookings.edu/wp-content/uploads/2018/08/wp43-8.23.18.pdf https://www.brookings.edu/wp-content/uploads/2018/08/wp43-8.23.18.pdf https://doi:10.7763/joebm.2015.v3.265 https://nbebank.com/wp%20content/uploads/pdf/annualbulletin/annual%20report%202019-2020.pdf https://nbebank.com/wp%20content/uploads/pdf/annualbulletin/annual%20report%202019-2020.pdf https://nbebank.com/wp%20content/uploads/pdf/annualbulletin/annual%20report%202019-2020.pdf https://ethiopia.opendataforafrica.org/rocbuue/country-and-regional-level-consumer-price-indices-november-2017 https://ethiopia.opendataforafrica.org/rocbuue/country-and-regional-level-consumer-price-indices-november-2017 https://ethiopia.opendataforafrica.org/rocbuue/country-and-regional-level-consumer-price-indices-november-2017 https://doi.org/10.1596/978-1-4648-0913-2 https://doi.org/10.1596/978-1-4648-0913-2 http://localhost/xmlui/handle/123456789/3020 http://localhost/xmlui/handle/123456789/3020 http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/58657 http://erepository.uonbi.ac.ke:8080/xmlui/handle/123456789/58657 murad and beyan east african journal of sciences volume 15 (1) 51-60 60 ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (2) 141-150 _____________________________________________________________________________________________ licensed under a creative commons *corresponding author. e-mail: hussenebrahim199@gmail.com attribution-non-commercial 4.0 international license. effects of nitrogen fertilizer rate and cutting height on morphological characteristics and yield of elephant grass (pennisetum purpureum l.) hussen ebrahim1*, fasil negussie1, and getachew animut2 1department of animal production and technology, woldia university, p.o. box 400, woldia, ethiopia 2ethiopian agricultural transformation agency (ata), addis ababa, ethiopia abstract background: elephant grass (pennisetum purpureum l.) is a forage grass with high potential to improve livestock production. however, the dry matter yield of the forage crop is low because of poor agronomic and soil fertility management practices. objectives: this study was, therefore, conducted to evaluate the effects of nitrogen fertilizer rate and cutting height on morphological characteristics and yield of elephant grass (p. purpureum l.). materials and methods: treatments were arranged in a 3 x 4 factorial arrangement in a randomized complete block design with three replications (3 cutting heights i.e., 7.5, 15, and 22.5 cm; and 4 nitrogen fertilizer rate i.e., 0, 69, 115, and 161 kg n ha-1). data on morphological characteristics and yield of elephant grass (p. purpureum l.) were collected and subjected to the analysis of variance using the general linear model procedure of the statistical analysis system version 2004. results: most morphological characteristics of elephant grass increased (p < 0.05) as cutting height and nitrogen fertilizer rate increased, except for weight per tiller, tiller diameter, and internode length. forage dry matter yield was in the order of 0 < 69 < 115 = 161 kg n ha-1 and 7.5 < 15 = 22.5 cm. looking at the combination of the two factors 115 kg n ha-1 x 22.5 cm and 161 kg n ha-1 x 15 cm treatments resulted in greater dry matter yield of 6.25 and 6.45 ton dm ha-1 cut-1, respectively, and 115 kg n ha-1 was economically feasible. conclusions: this study suggests that the rate of 115 kg n ha-1 x 22.5 cm cutting height is optimum for intensive cultivation of the forage crop with high dry matter yield at reduced nitrogen fertilizer cost. keywords: forage dry matter; internode length; tiller diameter; tiller weight 1. introduction one of high yielding potential improved forage to increase the productivity of animals, which can be cultivated both in the dry and wet seasons of ethiopia, is elephant grass (feleke assefa et al., 2015). in spite of the potential for high yields, on-farm yields of elephant grass are much lower and variable depending on management factors such as the application of manure and/or fertilizer, cutting management, and weed control (rahetlah et al., 2014; feleke assefa et al., 2015). furthermore, soil fertility, environmental factors, disease and pest, planting method, and variety largely determine the biomass yield and nutritive value of elephant grass (kabirizi et al., 2015). appropriate nitrogen fertilizer rate and cutting management are also essential for high production and quality of elephant grass (jorgensen et al., 2010; tessema zewdu et al., 2010b). the rate of nitrogen fertilizer application determines the cost and biomass production of elephant grass where inhibition of plant growth and unprofitability are the main results caused by the deficit and excessive use of nitrogen fertilizer (sant’ana et al., 2018). nitrogen fertilizer at the doses of 200 to 600 kg ha-1 tended to increase the harvested herbage of elephant grass by 30 to 50% (singh et al., 2013). on the other hand, as documented by na et al. (2014), this grass removed about 183 kg n ha-1 year-1 when cutting to a 12 cm stubble height. therefore, there is a need to find the appropriate rate of n fertilizer that provides greater efficiency in dry matter production and quality of elephant grass as animal forage. information on the effects of cutting height on elephant grass is either scarce or lacking in different parts of ethiopia (tessema zewdu et al., 2010a). applying appropriate cutting height is among the major agronomic practices to maximize the yield of elephant grass (wijitphan et al., 2009; jorgensen et al., 2010). cutting of elephant grass close to the ground level may negatively affect the re-growth ability by reducing tiller development. the optimal cutting height of this grass reported for higher dry matter yield and leaf content is 30 cm and 20 cm, respectively (jørgensen et al., 2010). even though little information is available about the hussen et al. east african journal of sciences volume 14 (2) 141-150 142 separate effect of n fertilizer as well as cutting height, the combined effects of nitrogen fertilizer rate and cutting height on morphological characteristics and yield of elephant grass are not well understood. hence, this study was carried out to evaluate the effects of nitrogen fertilizer rate and cutting height on morphological characteristics and yield of elephant grass (p. purpureum l.) and determine economically feasible n fertilizer rate to produce the forage crop. 2. materials and methods 2.1. description of the study area the experiment was conducted at mersa college of agriculture campus, woldia university, northeastern ethiopia, from june to november 2018. the campus is located at an altitude of 1600 meters above sea level between 11°40′n–11°66.7′n latitude, and 39°39.5′e– 39°65′e longitude. the area has a bimodal rainfall pattern (long summer and short autumn seasons) which ranges between 650 to 700 mm with an average annual temperature of 21 oc. the soil classification of the experimental area is clay loam. 2.2. description of experimental materials the source of the plant material, elephant grass, was mersa college of agriculture campus where the grass is well adapted. nitrogen fertilizer was used in the form of urea (46% nitrogen). 2.3. experimental design and treatments the experiment consisted four levels of nitrogen fertilizer (0, 69, 115, and 161 kg n ha-1), and three cutting heights (7.5 cm, 15 cm, and 22.5 cm) above the ground, resulting in 12 treatment combinations per block (5 x 41.5 = 207.5 m2). the experimental plot was laid out as a randomized complete block design in a factorial arrangement and replicated three times per treatment. the plot size was 5 m x 3 m (15 m2) and there were 36 plots. the spacing between plots and blocks were 0.5 and 1 m, respectively. while the spacing between rows and plants was 1 m and 0.5 m, respectively (tessema zewdu, 2008) and hence each plot accommodated 30 stems or plants (5 rows per plot). the required land was plowed by using a tractor once and bullock twice and the experimental plots were prepared after the land was smoothened. the parent plants were cut into stems with three nodes as equal to the pits and were planted (20 cm depth) at an angle of about 45o to bury two nodes into the soil. then treatment plots were fertilized with half of the nitrogen at the rate of 0, 69, 115, and 161 kg ha-1 in the form of urea (46% n) after 7 days of the first harvest (90 days of planting) and the other half was applied after 35 days of the first harvest. the entire plot area was kept weed-free with hand hoeing at the time of land preparation, and the weed was removed manually at 30 and 60 days after planting, 5, and 35 days after the first harvest. 2.4. data collection all samples were taken from the net plot area of 2 m x 3 m (6 m2) (three middle rows) a day before the second harvest to minimize the effect of border rows. a sample of five plants was randomly selected from the net plot area of each plot and used for the evaluation of all morphological parameters, except for tillers per plant, the basal circumference of the plant, and tiller weight, which were measured from other five representative tillers of plant samples. plant height was determined by measuring the plant beginning from its base to the longest leaf with a steel tape. tiller number was determined by direct counting of the tillers from five plants that were randomly selected. the basal circumference of the plant is the circumference of a collection of tillers per plant and was measured using meter around the base of elephant grass. the number of nodes per plant and internodes length (cm) was taken from those randomly selected stems or tillers per plot. the tiller diameter was measured with a caliper approximately 10 cm above the soil surface. since elephant grass stems are oval-shaped, stem diameter was measured at its widest point. green forage yield per hectare was estimated from the net plot area at 60 days after the first harvest based on green herbage cut with a sickle (wangchuk et al., 2015). then the harvested green forage was weighted using a balance, recorded and about 400 gram subsamples were taken from each plot for the determination of dry matter yield (dmy). the samples were oven-dried at 65 0c for about 72 hours in an air circulating electric oven (aoac, 1990) and were used to calculate the total dmy in terms of tons per hectare. 2.5. data analysis data were analyzed using analysis of variance (anova) of the general linear model (glm) procedure of the statistical analysis system (sas, 2004). treatment means were separated using turkey hsd (honestly significant difference) test at p < 0.05. the anova model for data analysis consisted of the effects of the block, n fertilizer rate, cutting height, and interaction of fertilizer rate and cutting height. the model used for the analysis was: yijl = μ + bl + fi + cj + fcij + eijl where; yijl =individual observations μ = overall mean bl = effect of the lth block fi = effect of nitrogen fertilizer rate cj = effect of cutting heights fcij =interaction effect of nitrogen fertilizer rate and cutting heights eijl = standard error of the mean hussen et al. morphology and yield of elephant grass 143 2.6. partial budget analysis partial budget analysis for this experiment was performed according to upton (1979) to evaluate the profitability of the treatments. it was assessed by the variable costs of fertilizer and labor. the sale price of elephant grass was estimated using local market observations. the difference in the sale and purchase of all inputs in each treatment was considered as a total return (tr). the net return (nr) was calculated by subtracting the total variable cost (tvc) from the total return (tr): nr = tr – tvc the change in net return (∆nr) was calculated as the difference between the change in total return (∆tr) and the change in total variable cost (∆tvc) as: ∆nr = ∆tr – ∆tvc the marginal rate of return (mrr) measures the increase in nr and is associated with each additional unit of expenditure (∆tvc), which was the difference among the three rates of nitrogen fertilizer excluding positive control and normally expressed as a percentage. mrr = ∆nr/∆tvc*100. 3. results and discussion 3.1. effects of nitrogen fertilizer and cutting height on morphological characteristics the number of tillers per plant of elephant grass was significantly (p < 0.05) affected by cutting height, rate of n fertilizer, and their interaction effects (table 1). generally, the number of tillers per plant increased with increasing n fertilizer rate and cutting height. this may be attributed to a consequence of higher nutrient synthesis and reserve in the stem of the plant at higher n fertilizer application that might have promoted more tiller production per plant. the effect of n fertilizer on the number of tillers per plant of elephant grass in previous studies was not consistent. while some reported increases in the number of tillers per plant due to the n fertilizer rate (oliveira et al., 2015; stida et al., 2018), others noted no effect (norsuwan et al., 2014). contrary to the results of this study, jørgensen et al. (2010) and tessema zewdu et al. (2010a) reported no effect of cutting height on the number of tillers per plant. the numbers of tillers per plant noted in this study were within the range of 20.9 to 47.6 obtained by sollenberger et al. (2014), although others noted higher tiller number per plant ranging from 50 to 125 with dwarf varieties (rengsirikul et al., 2013; wangchuk et al., 2015). cutting height and rate of n fertilizer application had a significant (p < 0.05) effect on tiller weight of elephant grass, and tiller weight decreased as the cutting height and rate of n fertilizer increased (table 1), which might be attributed to the higher tiller density per plant that tended to have thinner stems of tillers. the interaction effect of n fertilizer application rate and cutting height was also significant (p < 0.05) but with no apparent particular trend. the significant decline in mean tiller weight with increased cutting height agrees with other reports (wadi et al., 2004; wijitphan et al., 2009). however, jorgensen et al. (2010) observed no statistical differences in the mean weight per tiller among cutting heights of 0 and 20 cm. the interaction of cutting height and rate of n fertilizer had a significant (p < 0.05) effect on tiller diameter. the thicker tiller (2.93 cm) was obtained from 22.5 cm x 161 kg n ha-1 followed by (2.67 cm) at 7.5 cm x 69 kg n ha-1 while the thinnest (1.13 cm) tiller was obtained from 15 cm x 69 kg n ha-1 (table 1). similar to the results of the current study, stida et al. (2018) reported that the tiller diameter was not affected by the dose of n fertilizer. however, oliveira et al. (2015) observed differences in stem diameter among levels of n fertilizer of 100 to 1600 kg n ha-1). sollenberger et al. (2014) and wangchuk et al. (2015) reported that tiller diameter ranging from 1.1 to 1.9 cm, which was within the range reported in the current study. however, sinaga et al. (2016) found a thicker tiller (3.5–7 cm) without n fertilizer application, which was 146% thicker than the mean results of the current study. plant height was increased with increasing cutting height and the rate of n fertilizer (p < 0.05). the tallest plant was recorded for the combined treatment of 22.5 cm x 161 kg n ha-1 (2.81 m) which was more than threefold than the height of plants obtained from the combined treatment of 7.5 cm x 0 kg n ha-1 (0.8 m). this could be due to the high decapitation and death of the plants at 7.5 cm cutting height (sousa et al., 2010). the grass fertilized with 161 kg n ha-1 produced 2.6 times taller plants than the control treatment, and the grass harvested at the cutting height of 22.5 cm produced 1.3 times taller plants than the 7.5 cm cutting height, indicating that plant height is influenced more by n fertilizer rate than cutting height (na et al., 2014). a similar observation was made for the effects of cutting height (jørgensen et al., 2010) and n fertilizer rate (iica, 2016) on plant height. however, norsuwan et al. (2014) and oliveira et al. (2015) found a nonsignificant difference in plant height of napier grass due to the rate of n fertilizer. plant height of elephant grass ranging from 186.7 to 275.8 cm was reported when fertilized with 50 kg n ha-1 and cut at a height of 5 cm (mamaru tesfaye, 2018), which was within the range of values observed in the current study. the interaction effect of the rate of n fertilizer and cutting height had a significant (p < 0.05) effect on internode length. generally, internode length was in the hussen et al. east african journal of sciences volume 14 (2) 141-150 144 order of 0 < 69 < 115 = 161 kg n ha-1. on the contrary, mamaru tesfaye (2018) obtained lower internode length at a 5 cm cutting height with a mean value ranging from 6.7 to 12.9 cm, which could be attributed to the acidity of the soil (ph 4.2) and agroecological zone. the number of internodes was affected (p < 0.05) by cutting height, the rate of n fertilizer application as well as their interaction. the highest number of internodes per tiller was at the highest cutting height and the rate of n fertilizer, and vice versa. this could be because of the fastest growth in higher cutting height and n fertilizer rate. mamaru tesfaye (2018) noted a similar observation. however, tessema zewdu et al. (2010a) observed no significant difference among cutting heights for napier grass with a relatively lower number of internodes per tiller of 2.4 to 2.9. the basal circumference of the plant increased significantly (p < 0.05) as cutting height and the rate of n fertilizer increased but the interaction effect was not significant (p > 0.05; table 1). the increment in basal circumference per plant with an increase in n fertilizer rate and cutting height was in line with the report of wangchuk et al. (2015). the basal circumference of the grass in the current study (90 to 161 cm) was lower than the value reported by tessema zewdu (2008) (125–198.7 cm), which could be due to the difference in the agro-ecological zone and soil fertility. hussen et al. morphology and yield of elephant grass 145 table 1. effects of cutting height, rate of nitrogen fertilizer, and their interaction on morphological characteristics of elephant grass. parameter cutting height nitrogen fertilizer rate in kg n ha-1 cutting height in cm p-value 0 69 115 161 sem 7.5 15 22.5 sem c n c x n tn 7.5 21c 30b 35a 37a 0.67 30.8c 33.8b 37.8a 0.33 <.0001 <.0001 0.0041 15 24d 31c 38b 42a 22.5 29c 33b 43a 46a mean 24.7d 31.3c 38.7b 41.7a 0.39 tw 7.5 109.5b 93.0c 122.3a 102.1bc 2.20 106.7a 102.3b 91.8c 1.10 <.0001 <.0001 <.0001 15 109.9b 131.2a 81.3c 86.6c 22.5 123.0a 83.7b 92.8b 67.7c mean 114.1a 102.7b 98.8b 85.5c 1.27 td 7.5 2.27ab 2.67a 1.57b 1.40b 0.208 1.98 1.92 2.18 0.104 0.2066 0.0782 <.0001 15 1.53ab 1.13b 2.53a 2.47a 22.5 1.63b 2.40ab 1.73b 2.93a mean 1.81 1.94 2.07 2.27 0.12 ph 7.5 0.8d 1.3c 1.9b 2.1a 0.013 1.53c 1.84b 2.03a 0.007 <.0001 <.0001 <.0001 15 0.95d 1.5c 2.3b 2.6a 22.5 1.1d 1.7c 2.5b 2.81a mean 0.95d 1.5c 2.23b 2.5a 0.008 inl 7.5 14.3c 16.0bc 20.9a 20.2a 0.67 18.6 18.4 17.8 0.33 0.269 <.0001 0.0305 15 14.0c 16.3bc 21.7a 21.7a 22.5 13.3c 19.3ab 21.5a 20.2a mean 13.9c 17.2b 21.4a 20.7a 0.39 nn 7.5 5.33c 7.63b 8.40b 9.80a 0.233 7.79c 9.00b 9.85a 0.116 <.0001 <.0001 0.0008 15 6.00d 8.60c 10.00b 11.40a 22.5 7.00d 8.40c 11.00b 13.00a mean 6.11d 8.21c 9.8b 11.4a 0.135 bc 7.5 90 114 129 136 2.47 117c 126b 136a 1.24 <.0001 <.0001 0.1060 15 101 119 140 145 22.5 108 123 150 161 mean 100d 119c 140b 147a 1.43 note: means in a row within a category with different superscripts differ (p<0.05); tn = tiller numbers per plant; tw = tiller weight (g dm per tiller); td = tiller diameter (cm); ph = plant height (m); inl = internode length (cm); nn = number of internodes per tiller; bc = basal circumference (cm); sem = standard error of the mean; c = cutting height; n = nitrogen fertilizer rate. hussen et al. east african journal of sciences volume 14 (2) 141-150 146 3.2. green forage and dry matter yield of elephant grass cutting height, rate of n fertilizer application, as well as their interaction had a significant effect (p < 0.05) on green forage yield (gfy) and dry matter yield (dmy) of elephant grass (table 2). both gfy and dmy were lower (p < 0.05) for the 7.5 cm cutting height than the other cutting height that had similar values (p > 0.05). this could be associated with the higher tiller number and plant height with an increase in cutting height. wadi et al. (2004) reported that a higher dmy at 0 cm than at 30 cm cutting height. the application of a higher rate of n fertilizer resulted in double gfy and dmy over the unfertilized group, which could be attributed to the higher number of tillers along with the taller grass (ansah et al., 2010). however, there was no statistical difference between the n fertilizer rate of 115 and 161 kg n ha-1 in dmy. the current result revealed that the combination of 22.5 cm and 161 kg n ha-1 and 15 cm and 161 kg n ha-1 produced 2.4 and 2.6 times gfy and dmy, respectively as compared to the combined effect of the lowest cutting height and no fertilizer. the current result on gfy was in line with other studies conducted on different accessions of napier grass (oliveira et al., 2015; mamaru tesfaye, 2018). oliveira et al. (2015) reported that the dmy increased as the n fertilizer increased from 100 to 1600 kg n ha-1. norsuwan et al. (2014), on the other hand, reported that 240 kg n ha-1 application was sufficient to produce the highest dry matter yield. 3.3. partial budget analysis of elephant grass growing under four nitrogen fertilizer rates the rate of n fertilizer application determines the cost and biomass production of elephant grass (sant’ana et al., 2018) so that partial budget analysis is very vital to evaluate its’ economic feasibility (oliveira et al., 2015). in the current experiment, the partial budget analysis was done to evaluate the smallholder farmers’ profitability by producing elephant grass fertilized with different rates of n (table 3). the result of the partial budget analysis revealed that fertilizing elephant grass with n resulted in a relatively higher return over the control group. although the change in net return was positive across all the rates of n fertilizer, it was higher for elephant grass fertilized with 115 kg n ha-1 (7501.4 etb) compared to the other rate of n fertilizer. the result of this study showed that per unit of expenditure could result in a return of 0.648, 0.862, and 0.644 etb per unit of investment for 69, 115, and 161 kg n ha-1, respectively. therefore, fertilizing the elephant grass at 115 kg n ha-1 was economically feasible because it resulted in a high net return than the other rate of n fertilizer and hence it could be recommended for smallholder elephant grass producers as a fodder crop. hussen et al. morphology and yield of elephant grass 147 table 2. effects of cutting height, rate of nitrogen fertilizer, and their interaction on green forage and dry matter yield of elephant grass. parameter cutting height nitrogen fertilizer rate in kg n ha-1 cutting height in cm p-value 0 69 115 161 sem 7.5 15 22.5 sem c n c x n gfy 7.5 17.28b 20.94b 22.50b 25.11a 1.318 21.46b 30.38a 31.75a 0.659 <.0001 <.0001 <.0001 15 18.61d 27.22c 34.19b 41.50a 22.5 16.83c 31.37b 37.03ab 41.79a mean 17.56d 26.51c 31.24b 36.13a 0.761 tdmy 7.5 2.45b 2.98b 4.36a 4.33a 0.25 3.53b 4.85a 4.7a 0.125 <.0001 <.0001 <.0001 15 2.80c 5.51ab 4.65b 6.45a 22.5 2.95c 4.38b 6.25a 5.24ab mean 2.73c 4.29b 5.09a 5.34a 0.144 note: means in a column and within a category with different superscripts differ at p<0.05; gfy = green forage yield (ton ha-1); tdmy = total dry matter yield (ton dm ha-1); sem = standard error of the mean; c = cutting height; n = nitrogen fertilizer rate. table 3. partial budget analysis of elephant grass fertilized with different nitrogen rates. descriptions treatments control group 69 kg n ha-1 115 kg n ha-1 161 kg n ha-1 dry matter yield in ton dm ha-1 2.73 4.29 5.09 5.34 selling price in etb ha-1 18741.5 29450.9 34942.9 36659.1 purchasing price of urea fertilizer in etb ha-1 0.0 3300.0 5500.0 7700.0 cost of labor for land and pit preparation in etb ha-1 6000.0 6000.0 6000.0 6000.0 cost of labor for planting, harvest, and supplementary irrigation in etb ha-1 5250.0 5250.0 5250.0 5250.0 cost of labor for fertilizer application in etb ha-1 0.0 3200.0 3200.0 3200.0 cost of labor for weed management in etb ha-1 5000.0 5000.0 5000.0 5000.0 tvc 0.0 6500.0 8700.0 10900.0 tr 2491.5 13200.9 18692.9 20409.1 nr 2491.5 6700.9 9992.9 9509.1 δtvc 6500.0 8700.0 10900.0 δtr 10709.4 16201.4 17917.6 δnr 4209.4 7501.4 7017.6 mrr 64.8 86.2 64.4 note: tvc = total variable cost (etb ha-1); tr = total return (etb ha-1); nr = net return (etb ha-1); δtvc = change in total variable cost (etb ha-1); δtr = change in total return (etb ha-1); δnr = change in net return (etb ha-1); mrr = marginal rate of return (%) and etb = ethiopian birr. hussen et al. east african journal of sciences volume 14 (2) 141-150 148 4. conclusions this study demonstrated that both cutting height and n fertilizer rate had a significant effect on the morphological characteristics and on forage yield of elephant grass. forage yield and morphological characteristics increased in response to increasing the rate of n fertilizer and cutting height. however, the dry matter yield for 115 (5.09 ton dm ha-1) and 161 (5.34 ton dm ha-1) kg n ha-1 fertilizer rate and 15 (4.85 ton dm ha-1) and 22.5 (4.7 ton dm ha-1) cm cutting heights were similar. looking at the combination of the two factors 115 kg n ha-1 x 22.5 cm and 161 kg n ha-1 x 15 cm treatments resulted in greater dmy and 115 kg n ha-1 was observed as an economically feasible n fertilizer rate, suggesting 115 kg n ha-1 x 22.5 cm to be recommended for farmers to grow as it may lead to economical forage production due to reduced n fertilizer cost. 5. acknowledgments the authors thank the ethiopia ministry of science and higher education for financing the study and woldia university for facilitating the research. thanks are also due to dr. solomon tsegaye for his immense help during experimental plot preparation and data collection. 6. references ansah, t., osafo, e.l.k. and hansen, h.h. 2010. herbage yield and chemical composition of four varieties of napier (pennisetum purpureum) grass harvested at three different days after planting. agriculture and biology journal of north america, 1(5): 923–929. aoac (associations of official analytical chemists). 1990. official methods of the analysis. 15th edition. arlingston, virginia, usa. feleke assefa, tsegaye ano, teshale aba and zehara ebrahim. 2015. assessment of improved forage types and their utilization in shashogo woreda, hadiya zone, southern ethiopia. global journal of animal science, livestock production, and animal breeding, 3(6): 227–230. iica (inter-american institute for cooperation on agriculture). 2016. feasibility study of the commercial production of biofuels from dedicated biomass crops on mined-out bauxite lands in moengo, suriname. final report. iica, moengo, suriname. jorgensen, s.t., pookpakdi, a., tudsri, s., stolen, o., ortiz, r. and christiansen, j.l. 2010. cultivar-bycutting height interactions in napier grass (pennisetum purpureum schumach) grown in a tropical rain-fed environment. acta agriculturae scandinavica, section bsoil and plant science, 60: 199– 210. kabirizi, j., kawube, g., mulaa, m., namazzi, c., mugerwa, g., et al. 2015. screening napier grass (pennisetum purpureum) accessions for dry matter yield and tolerance to napier stunt disease in uganda. pp. 236–242. in: kabirizi, j., muyekho, f., mulaa, m., msangi, r., pallangyo, b., kawube, g., zziwa, e., mugerwa, s., ajanga, s., lukwago, g., wamalwa, n.i.e., kariuki, i., mwesigwa, r., nannyeenyantege, w., atuhairwe, a., awalla, j., namazzi, c. and nampijja, z. 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g.d.a., augusto, j., et al. 2015. variation of morpho-agronomic and biomass quality traits in elephant grass for energy purposes according to nitrogen levels. american journal of plant sciences, 6: 1685–1696. rahetlah, v.b., randrianaivoarivony, j.m., andrianarisoa, b. and ramalanjaona, v.l. 2014. yield response of elephant grass (pennisetum purpureum) to guano organic fertilizer in the highlands of madagascar. livestock research for rural development, 26(1). rengsirikul, k., ishii, y., kangvansaichol, k., sripichitt, p., punsuvon, v., et al. 2013. biomass yield, chemical composition, and potential ethanol yields of 8 cultivars of napier grass (pennisetum purpureum schumach.) harvested 3-monthly in central thailand. journal of sustainable bioenergy systems, 3: 107–112. sant’ana, j.a.a., daher, r.f., ponciano, n.j., santos, m.m.p., viana, a.p., et al. 2018. nitrogen and phosphate fertilizers in elephant-grass for energy use. african journal of agricultural research, 13(16): 806–813. sas 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value of napier grass (pennisetum purpureum (l.) schumach). grass and forage science, 65(4): 421–430. upton, m. 1979. farm management in africa: the principle of production and planning. oxford, uk: oxford university press. wadi, a., ishii, y. and idota, s. 2004. effects of cutting interval and cutting height on dry matter yield and overwintering ability at the established year in pennisetum species. plant production science, 7(1): 88–96. wangchuk, k., rai, k., nirola, h. and dendup, c. 2015. forage growth, yield, and quality responses of napier hybrid grass cultivars to three cutting intervals in the himalayan foothills. tropical grasslands – forrajes tropicales, 3: 142–150. wijitphan, s., lorwilai, p. and arkaseang, c. 2009. effect of cutting heights on productivity and quality of king napier grass (pennisetum purpureum cv . king grass ) under irrigation. pakistan journal of nutrition, 8(8): 1244–125. hussen et al. east african journal of sciences volume 14 (2) 141-150 150 ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15 (1) 41-50 licensed under a creative commons *corresponding author: zalemu56@gmail.com attribution-noncommercial 4.0 international license. sequential application of various insecticides for the management of cotton bollworm (hubner) helicoverpa armigera (lepidoptera: noctuidae) in cotton production zemedkun alemu 1*, ferdu azerefegne 2, and geremew terefe 3 1werer agricultural research center, eiar, p.o. box 2003, addis ababa, ethiopia 2college of agriculture, hawassa university, p.o. box 770, hawassa, ethiopia 3sesame business network ethiopia abstract background: cotton bollworm (hubner) (helicoverpa armigera) (lepidoptera: noctuidae) is a major constraint to cotton production and productivity in ethiopia. objective: to determine the best spray sequence of various insecticides as a strategy of resistance management of the pest. materials and methods: field experiments were conducted during the 2017 and 2018 main cropping season at werer agricultural research center. eight different insecticides (chlorantraniliprole, deltamethrin, chlorfenapyr, lufenuron+profenofos, chlorpyriphos, lambdacyhalothrin, profenofos, and alphacypermethrin) belonging to five major insecticide classes were systematically arranged in six treatments and three spraying sequences along with a control treatment. the experiment was laid out as a randomized complete block design and replicated four times per treatment. data were collected on bollworm population, damaged squares, flowers, and bolls at pre and post insecticide application, boll number per plant, and seed cotton yield. using the modified abbott’s formula, the percent efficacy was computed. results: significant differences (p<0.05) were observed among the treatments for post spray larvae count, damaged squares, and boll counts in the 2017 and 2018 cropping seasons. sequential and rotational application of a cocktail of the insecticides, namely, chlorantraniliprole, chlorfenapyr, profenofos, and chlorfenapyr, chlorantraniliprole, lufenuron+profenofos resulted in the best control with 81.8% and 76.4% of h. armigera larvae controlling efficacy. the lowest average cotton boll number (9.69/plant) and cotton yields (2.24 ton/ha) were obtained from the unsprayed treatment. conclusion: applying the insecticides in sequence increased seed cotton yield by 36.2% and 33.9% compared to the yields obtained from the unsprayed plots. the results imply that rotational use of insecticides with different modes of action is the best strategy to control the pest. keywords: bolls; bollworm; flowers; mode of action; pyrethroids; squares; yield 1. introduction in ethiopia, cotton is one of the most widely cultivated crops both by small and large-scale cotton producers. presently, production of the cotton crop has become an attractive trade for foreign and local investors which could help the country in terms of providing job opportunities and as a source of foreign exchange earnings (belay, 2012 cited by eiar, 2016). however, the pest spectrum of cotton is quite complex among which insect pest problem has become the major one. a total of seventy species of insects and mites have been known to attack cotton at different growth stages in ethiopia (ermias et al., 2009) out of which bollworm complex (helicoverpa armigera, pectinophora gossypiella, diparopsis watersi, and earias spp) is a great menace. cotton bollworm, helicoverpa armigera (hubner) (lepidoptera: noctuidae) is a polyphagous insect damaging diverse crops, such as beans, chickpea, peas, sorghum, cotton, tomato, pepper, sunflower, safflower, flax, and niger seed (tsedeke abate, 1982; waktole sori, 1996). in ethiopia, bollworm complexes cause 36–60% yield losses among which h. armigera is a major culprit (tsedeke abate, 1982; waktole sori, 1996; geremew terefe and ermias shonga, 2006). all parts of the cotton plant are vulnerable to attack by the pest. the larva feeds on cotton young leaves, squares, flower buds, flowers, and bolls (geremew and ermias, 2006; deguine et al., 2008). in china, cotton bollworms caused about 50– 60% yield reduction each year from 1980–1990 on cotton (xiao et al., 2002). cotton pest management is the most important task in the total production cost of cotton in most years. cotton farms can lose the whole production when correct pest managements are not taken. among production control costs, 43 % is spent on pesticide purchase, and 33 % on weed control efforts (eiar, 2016). in ethiopia, for decades, a wide range of insecticides have been used for the control of cotton insect and mite pests, particularly cotton bollworm (ermias shonga et al., 2009). control of pests with insecticides from a single chemistry group is mailto:zalemu56@gmail.com zemedkun et al. east african journal of sciences volume 15 (1) 41-50 42 common in most cotton farms and such a practice for an extended period results in the development of resistance as in the case of lambda-cyhalothrin for cotton bollworm species at dubti (germew terefe, 2004), dimethoate for aphid species at the middle awash (iar, 1990), and carbamate group (carbosulfan, furathiocarb and pirimicarb) for aphid species resistance at arbaminch, dubti and werer (ermias shonga, 2006). additionally, studies on the screening of different insecticides for cotton bollworm control showed a declining efficacy of endosulfan at werer agricultural research center (warc) (warc, 1998) and commercial farms in ethiopia (geremew terefe and surachate, 2005). application of different insecticides sequentially resulted in significant reductions in larval population as compared with repeated applications of the same insecticide (salama et al., 2013). helicoverpa armigera is a multi-resistant insect species; it can express more than one resistance mechanism to a particular insecticide group (muhammad, 2007). accordingly, designing an insecticide resistance management strategy for h. armigera is very crucial. the use of insecticide mixtures or mode of action rotation and sequential application is an important approach for managing insecticide resistance, which could delay or mitigate the onset of resistance development in arthropod pest populations (cloyd, 2010). pyrethroid insecticides are important in relation to other management options due to low tendency to accumulate in organism and short biodegradation period, and economic value led to overuse of pyrethriods with unavoidable consequences (bhardwaj et al., 2020). therefore, the present study was conducted to study the effectiveness of selected insecticide application sequences against h. armigera on cotton under field conditions. 2. materials and methods the experiment was conducted at werer agricultural research center (warc), amibara district, gebresu zone of afar national regional state during the 2017 and 2018 cropping seasons under field conditions using irrigation. warc is located at an altitude of 750 meter above sea level, at the latitude of 9o 20' 31"n, and longitude of 40o10' 11" e. the study areas is characterized by a mean annual rainfall of 540 mm which is erratic and mean maximum and minimum temperatures of 34.4 oc and 19.6 oc, respectively. the soil is vertisol with porosity and bulk density (0– 25cm depth) of 49.06% and 1.35 g cm–2, respectively (wendmagen chekole and abere mnalku, 2012). 2.1. description of the materials used for the research 2.1.1. planting material the popular cotton variety used for the study was deltpine-90, which was obtained from werer agricultural research center (warc). 2.1.1. insecticides eight different insecticides were used for the experiment. these insecticides are recommended for the control of cotton bollworm on cotton by warc (table 1). table 1. description of insecticides used in the experiment. common name trade name chemical group rate/ha chlororfenapyr tutan 36 sc pyrole 225 ml chlorantraniliprole coragen 200 sc diamide 125 ml deltamethrin decis 2.5 ec pyrethroid 600 ml lambda-cyhalothrin karate 5 % ec pyrethroid 400 ml alpha-cypermethrin fastac 100 g/lt pyrethroid 300 ml chlorpyriphos pyriban 48 % ec organophosphate 2000 ml profenofos proof 720 g/lt organophosphate 900 ml lufenuron+profenofos curador 55 ec igr+organophosphate 650 ml note: ec = emulsifiable concentrate, sc = soluble concentrate, igr = insect growth regulators. 2.2. treatments and experimental design the eight insecticides were systematically arranged in to six treatments (including one untreated check) and three spraying sequences (table 2). the experiment was laid out as a randomized complete block design (rcbd) with four replications per treatment. an individual total plot size was 63 m2. the distance between the row to row and plant to plant was 90 cm and 20 cm, respectively. zemedkun et al. sequential application of insecticides for cotton bollworm management 43 2.3. experimental procedures 2.3.1. planting date and methods the land was prepared by a tractor operated machine. planting was done on 26 may 2017 and 21st may 2018 by hand. the plots were irrigated eight times by giving a 10-day interval after first irrigation and then watering every at the interval of 15 days up to the time of 65% boll opening period. plots were weeded twice by hoeing and hand-weeded two times. all other recommended agronomic practices were applied to the plots. on each plot inspecting h. armigera infestation was started three weeks after germination and continued until the cotton plants matured. ten plants per plot were randomly taken and tagged for the assessment of h. armigera infestation by checking leaves, squares, flowers, and bolls. from the tagged plants data were recorded on h. armigera eggs and larvae, square, flower, and boll damage of h. armigera. on an experimental plot, a total of three rounds of spray were applied using a hand-operated knapsack sprayer based on natural infestation when the economic threshold level was 10 larvae per 100 plants (warc, 2015). the evaluated insecticide sprays were prepared according to the company’s recommended doses in a water application volume of 200 liters/hectare. 2.3.2. dates of spraying the first round spray application was made on july 6th, 2017, and june 28th, 2018 coinciding with the period of formation of the squares and flowers of the plant, and the subsequent two sprays were applied at a 15-day interval. the second round spray application coincided with the pick square and flower formation period and the third round application coincided with the boll formation and boll opening period of the cotton plant. ten plants were tagged in each plot and young shoot leaves, squares, flowers, and bolls were examined for data collection. cotton bollworm egg and larvae, damaged squares, flowers, and bolls; non-target and beneficial insects on pre and postspray count of 3, 5, 7, and 10 days were recorded. data were collected on the number of days after treatment. at crop maturity and just before cottonpicking, healthy bolls per plant were counted from the ten predetermined plants including on plants from the control plots. finally, seed cotton was harvested and weighed. 2.2. data analysis all data were analyzed using proc glm (sas version 9.0, sas institute, 1999). proc univariate was used to test data for normality and homogeneity of variance based on the shapirowilk statistic. to satisfy the assumptions of anova, the pre and post-spray count mean data were square root transformed (√x+0.5). when fvalues were significant (p < 0.05), means were compared by fisher's least significant difference (lsd) test. percent efficacy for each treatment was computed based on the modified abbotte’s formula by fleming and retenkarna, (1985). % efficacy = [1 − (ta ∗ cb) / (tb ∗ ca)] where, ta = post-treatment population in treatment, cb = pre-treatment population in check, tb = pretreatment population in treatment, ca = posttreatment population in check. zemedkun et al. east african journal of sciences volume 15 (1) 41-50 44 table 2. insecticide treatments for spray sequence in field experiments during the 2017 and 2018 cropping seasons at werer agricultural research centre, middle awash valley, ethiopia. treatment name sequence of treatment 1st spray 2nd spray 3rd spray t1 chlorantraniliprole 200 sc @ 150 ml/ha chlorfenapyr 36 sc @ 225 ml/ha profenofos 720 g/l @ 900 ml/ha t2 deltamethrin 2.5 ec @ 600 ml/ha lufenuron + profenofos 55 ec @ 650 ml/ha chlorfenapyr 36 sc @ 225 ml/ha t3 chlorfenapyr 36 sc @ 225 ml/ha chlorantraniliprole 200 sc @ 150 ml/ha lufenuron+profenofos 55 ec @ 650 ml/ha t4 lufenuron+profenofos 55 ec @ 650 ml/ha chlorfenapyr 36 sc @ 225 ml/ha alphacypermethrin 100 g/l @ 300ml/ha t5 chlorpyriphos 48 % ec @ 2l/ha lufenuron+profenofos 55 ec@650 ml/ha lambda-cyhalothrin 5% ec @ 480ml/ha t6 lambda-cyhalothrin 5 % ec @ 480ml/ha lambda-cyhalothrin 5 % ec @ 480 ml/ha lambda-cyhalothrin 5% ec @ 480ml/ha t7 unsprayed unsprayed unsprayed 3. results the results of the first round spray revealed that, the post spray larval and damaged square counts were significantly (p < 0.05) different among the treatments both in 2017 and 2018 cropping seasons (tables 3). in both cropping seasons, the highest larval count, square numbers, and numbers of damaged flowers were recorded from control treatment and the lowest were recorded from chlorfenapyr treated plots (tables 3). the results of the second round spray in the 2017 and 2018 cropping seasons revealed that the postspray mean larvae count, damaged squares, flowers, and bolls revealed significant (p < 0.05) variations among the different insecticides applied (tables 4). in both cropping years, among the tested insecticides, the highest larval controlling efficacy was obtained from spraying chlorfenapyr, while the lowest was from spraying lambda-cyhalothrin (tables 4). the third round spray showed a significant (p < 0.05) difference for the post-spray larvae counts and damaged boll counts among the treatments in the 2017 cropping season (table 5). in the 2018 cropping season, the post spray larval count, damaged squares, and boll count per plant revealed significant (p < 0.05) differences among the treatments (table 5). there was a significant difference (p < 0.05) in the number of boll per plant among the treatments in both cropping years (table 6). the highest numbers of boll per plant and seed cotton yield were obtained from the treatment with the rotation of chlorantraniliprole, chlorfenapyr, profenofos. however, the lowest numbers of boll per plant and seed cotton yield were obtained from the control treatment in both seasons (table 6). the rotation of chlorantraniliprole, chlorfenapyr resulted in cotton yield advantages of 0.72 and 0.75 ton/ha in the 2017 and 2018 seasons compared to the commonly and repeatedly used lambda-cyhalothrin (table 6). mailto:2.5ec@600ml/ha mailto:2.5ec@600ml/ha zemedkun et al. sequential application of insecticides for cotton bollworm management 45 table 3. means of pre and post-spray larva counts, damage square and damage flower, and efficacy of different insecticide tested at the 1st round spray application in a field experiment, werer, during the 2017 and 2018 cropping seasons. 2017 cropping season treatment name no. of larvae count/plant no. of damage squares/plant no. of damage flowers/plant % efficacy pre-spray post-spray pre-spray post-spray pre-spray post-spray t1:chlorantraniliprole 200 sc 0.15(0.81) 0.03(0.73)c 0.28(0.87) 0.06(0.75)c 0.03(0.72) 0.02(0.72) 79.89 t2:deltamethrin 2.5% ec 0.18(0.82) 0.13(0.79)ab 0.30(0.89) 0.14(0.80)b 0.08(0.75) 0.03(0.72) 31.04 t3:chlorfenapyr 36sc 0.20(0.83) 0.04(0.73)c 0.50(0.10) 0.04(0.74)c 0.08(0.76) 0.04(0.73) 81.90 t4:lufenuron+profenofos 55% ec 0.15(0.81) 0.04(0.74)c 0.28(0.88) 0.09(0.77)bc 0.03(0.72) 0.01(0.71) 71.84 t5:chlorpyriphos 48 % ec 0.20(0.84) 0.09(0.77)bc 0.30(0.89) 0.11(0.78)bc 0.08(0.75) 0.04(0.74) 54.74 t6:lambda-cyhalothrin 5 % ec 0.18(0.82) 0.08 (0.76)bc 0.28(0.87) 0.11(0.78)bc 0.10(0.77) 0.04(0.73) 55.17 t7:unsprayed 0.18(0.82) 0.18(0.82)a 0.15(0.81) 0.34(0.92)a 0.03(0.72) 0.06(0.74) lsd ( 0.05) ns 0.050 ns 0.051 ns ns cv (%) 8.15 4.44 12.47 4.34 10.43 4.96 2018 cropping season treatment name no. of larvae counts/plant no. of damage squares/plant no. of damage flowers/plant % efficacy pre-spray post-spray pre-spray post-spray pre-spray post -spray t1:chlorantraniliprole 200 sc 0.58(1.03) 0.06(0.77)c 0.85(1.12) 0.02(0.72)c 0.0(0.71) 0.03(0.73) 80.43 t2:deltamethrin 2.5% ec 0.33(0.90) 0.12(0.78)b 0.38(0.92) 0.68(1.07)ba 0.0(0.71) 0.08(0.76) 26.92 t3:chlorfenapyr 36sc 0.75(1.09) 0.09(0.77)b 0.95(1.18) 0.18(0.82)bc 0.05(0.74) 0.08(0.76) 75.00 t4:lufenuron+profenofos 55% ec 0.33(0.91) 0.04(0.73)b 0.30(0.89) 0.03(0.72)c 0.0(0.71) 0.02(0.72) 76.92 t5:chlorpyriphos 48 % ec 0.50(0.99) 0.02(0.81)b 0.50(0.96) 0.48(0.98)bac 0.05(0.74) 0.04(0.73) 40.00 t6:lambda-cyhalothrin 5 % ec 0.30(0.89) 0.09(0.77) b 0.18(0.81) 0.30(0.89) cb 0.0(0.71) 0.01(0.71) 41.67 t7:unsprayed 0.58(1.03) 0.29(0.88)a 0.78(1.08) 1.16(1.23)a 0.0(0.71) 0.09(0.77) lsd ( 0.05) ns 0.07 ns 0.29 ns ns cv (%) 11.9 6.34 20.5 21.7 2.9 4.1 note: means followed by the same letter(s) within a column are not significantly different from each other at a 5% level of significance. values in parentheses preand post-spray mean data were square-roottransformed. % efficacy = percent efficacy. zemedkun et al. east african journal of sciences volume 15 (1) 41-50 46 table 4. means of pre and post-spray counts of larvae counts, damage square, flower, bolls, and efficacy of different insecticides tested at the 2nd round rotation spray application, werer, during the 2017 and 2018 cropping seasons. 2017 cropping season treatment name no. of larvae count/ plant no. of damage square/ plant % efficacy no. damage flowers/ plant no. damage bolls/plant pre-spray post-spray mean pre-spray post-spray mean pre-spray post-spray mean pre-spray post-spray mean t1:chlorfenapyr 36 sc 0.40(0.95) 0.07(0.75)d 0.55(1.02) 0.13(0.79)d 85.61 0.23(0.85) 0.07(0.75) 0.08(0.76) 0.06(0.75) t2:lufenuron+profeno 55 ec 0.45(0.97) 0.15(0.81)bcd 0.73(1.11) 0.31(0.90)bcd 68.82 0.20(0.83) 0.12(0.79) 0.15(0.81) 0.12(0.79) t3:chlorantraniliprole 200 sc 0.38(0.93) 0.09(0.77)cd 0.50(0.99) 0.16(0.81)cd 76.61 0.15(0.80) 0.13(0.79) 0.18(0.82) 0.13(0.79) t4:chlorfenapyr 36 sc 0.40(0.95) 0.11(0.78)cd 0.95(1.16) 0.38(0.93)bcd 75.15 0.33(0.91) 0.14(0.80) 0.18(0.82) 0.11(0.78) t5:lufenuron+profeno 55 ec 0.50(0.10) 0.18(0.83)bc 1.23(1.30) 0.43(0.96)bc 66.09 0.23(0.85) 0.17(0.81) 0.23(0.84) 0.15(0.81) t6:lambdacyhalothrin 5%ec 0.48(0.99) 0.23(0.85)b 1.18(1.28) 0.58(1.03)b 55.69 0.33(0.91) 0.13(0.79) 0.28(0.88) 0.18(0.82) t7:unsprayed 0.55(1.02) 0.78(1.13)a 0.98(1.21) 1.13(1.27)a 0.25(0.86) 0.24(0.86) 0.05(0.74) 0.19(0.83) lsd ( 0.05) ns 0.06 ns 0.15 ns ns ns ns cv (%) 8.32 4.96 16.74 10.68 9.83 8.12 9.51 5.14 2018 cropping season treatment name no. of larvae count/plant no. of damage square/plant % efficacy no. damage flowers/plant no. damage bolls/plant pre-spray post-spray pre-spray post-spray pre-spray post-spray pre-spray post-spray t1:chlorfenapyr 36 sc 0.23(0.84) 0.05(0.74)b 0.28(0.88) 0.13(0.794)c 80.85 0.0(0.71) 0.03(0.73)c 0.03(0.72) 0.06(0.75)c t2:lufenuron+profeno 55 ec 0.55(1.61) 0.213(0.84)ba 0.98(1.19) 0.49(0.99)ba 66.71 0.10(0.77) 0.13(0.79)ba 0.30(0.89) 0.19(0.83)ba t3:chlorantraniliprole200sc 0.33(0.91) 0.113(0.78)b 0.60(1.03) 0.36(0.92)bac 70.18 0.15(0.80) 0.06(0.75)bc 0.23(0.85) 0.15(0.81)bac t4:chlorfenapyr 36 sc 0.20(0.84) 0.063(0.75)b 0.33(0.89) 0.27(0.87)bc 73.08 0.03(0.72) 0.07(0.75)bc 0.13(0.79) 0.09(0.77)bc t5:lufenuron+profeno 55 ec 0.50(0.99) 0.213(0.84)ba 0.83(1.13) 0.34(0.92)bac 63.38 0.03(0.72) 0.10(0.77)ba 0.30(0.89) 0.23(0.85)a t6:lambdacyhalothrin5%ec 0.43(0.96) 0.231(0.85)ba 0.73(1.10) 0.53(1.00)ba 53.12 0.10(0.77) 0.07(0.75)bc 0.28(0.88) 0.21(0.84)a t7:unsprayed 0.35(0.92) 0.406(0.95)a 0.50(0.99) 0.56(1.02)a 0.08(0.76) 0.16(0.81)a 0.20(0.84) 0.23(0.85)a lsd ( 0.05) ns 0.12 ns 0.14 ns 0.05 ns 0.06 cv (%) 9.22 9.50 15.41 10.14 8.64 3.94 7.47 5.29 note: means followed by the same letter(s) within a column are not significantly different from each other at a 5% level of significance. % efficacy = percent efficacy. values in parentheses of pre and post spray means data were square-root-transformed. zemedkun et al. sequential application of insecticides for cotton bollworm management 47 table 5. means of pre and post-spray larva counts, damage square, flower, bolls, and efficacy of different insecticides tested at the 3rd round rotation spray application, werer, 2017 and 2018 cropping seasons. 2017 cropping season treatment name no. of larvae count/plant no. damage squares/plant % efficacy no. damage flowers/plant no. damage bolls/plant pre-spray post-spray pre-spray post-spray pre-spray post-spray pre-spray post-spray t1:profenofos 72%ec 0.15(0.80) 0.03(0.73)b 0.28(0.87) 0.04(0.74) 79.89 0.13(0.79) 0.03(0.72) 0.18(0.82) 0.11(0.78)b t2:chlorfenapyr 36sc 0.25(0.86) 0.04(0.74)b 0.38(0.93) 0.03(0.73) 83.10 0.15(0.80) 0.03(0.73) 0.15(0.81) 0.09(0.77)b t3:lufenuron+profenofos 0.30(0.89) 0.08(0.76)b 0.33(0.90) 0.05(0.74) 76.86 0.15(0.81) 0.03(0.73) 0.25(0.86) 0.10(0.77)b t4:alphacypermethrin 100%ec 0.20(0.84) 0.04(0.73)b 0.25(0.86) 0.08(0.76) 81.90 0.10(0.77) 0.02(0.72) 0.28(0.87) 0.12(0.79)b t5:lambda-cyhalothrin 5%ec 0.18(0.82) 0.07(0.75)b 0.25(0.87) 0.07(0.75) 62.07 0.08(0.75) 0.03(0.72) 0.13(0.79) 0.10(0.77)b t6:lambda-cyhalothrin 5%ec 0.23(0.85) 0.10(0.77)b 0.30(0.894) 0.11(0.78) 57.09 0.28(0.88) 0.05(0.74) 0.23(0.85) 0.21(0.84)a t7:unsprayed 0.18(0.82) 0.18(0.86)a 0.25(0.86) 0.26(0.86) 0.25(0.86) 0.09(0.77) 0.25(0.86) 0.24(0.86)a lsd ( 0.05) ns 0.06 ns ns ns ns ns 0.048 cv (%) 7.98 5.28 8.71 8.98 8.71 4.11 12.18 4.00 2018 cropping season treatment name no. of larvae count/plant no. damage squares/plant % efficacy no. damage flowers/plant no. damage bolls/plant pre-spray post-spray pre-spray post-spray pre-spray post-spray pre-spray post-spray t1:profenofos 72%ec 0.30(0.89) 0.06(0.75)b 0.38(0.93) 0.03(0.72)b 84.27 0.10(0.77) 0.03(0.72) 0.20(0.84) 0.07(0.75)b t2:chlorfenapyr 36sc 0.33(0.91) 0.07(0.75)b 0.38(0.92) 0.04(0.74)b 82.26 0.15(0.80) 0.03(0.73) 0.18(0.82) 0.13(0.79)b t3:lufenuron+profenofos 0.28(0.88) 0.07(0.75)b 0.26(0.87) 0.08(0.76)b 79.03 0.15(0.80) 0.02(0.73) 0.28(0.88) 0.14(0.79)b t4:alphacypermethrin100%ec 0.33(0.91) 0.09(0.77)b 0.33(0.89) 0.08(0.76)b 75.82 0.08(0.76) 0.03(0.72) 0.25(0.87) 0.21(0.84)b t5:lambda-cyhalothrin 5%ec 0.30(0.89) 0.14(0.79)b 0.50(0.99) 0.13(0.79)b 61.56 0.08 (0.76) 0.04(0.74) 0.10(0.77) 0.16(0.81)b t6:lambda-cyhalothrin 5%ec 0.33(0.90) 0.16(0.81)b 0.38(0.93) 0.16(0.81)b 59.68 0.15(0.81) 0.03(0.72) 0.25(0.86) 0.19(0.82)b t7:unsprayed 0.33(0.91) 0.39(0.93)a 0.30(0.89) 0.36(0.92)a 0.08(0.76) 0.11(0.78) 0.25(0.87) 0.43(0.96)a lsd ( 0.05) ns 0.06 ns ns ns ns ns 0.05 cv (%) 7.98 5.28 8.71 8.98 8.71 4.11 12.18 4.00 note: means followed by the same letter(s) within a column are not significantly different from each other at 5% level of significance. % efficacy = percent efficacy. values in parentheses of pre and post spray mean data were square-root-transformed. zemedkun et al. east african journal of sciences volume 15 (1) 41-50 48 table 6. means of bolls number per plant and seed cotton yield in a field experiment, werer, during the 2017 and 2018 cropping seasons. treatment no. spray sequence of treatment 2017 cropping season 2018 cropping season healthy boll/plant seed cotton yield (t ha-1) healthy boll/plant seed cotton yield (t ha-1) 1st spray 2nd spray 3rd spray 1 chlorantraniliprole 200 sc @150ml/ha chlorfenapyr 36 sc @225ml/ha profenofos 720 g/l @900ml/ha 16.53a 3.84a 20.85a 3.17a 2 deltamethrin 2.5ec @600ml/ha lufenuron + profenofos 55ec @650ml/ha chlorfenapyr 36 sc @225ml/ha 12.85b 3.35bc 12.68b 2.48b 3 chlorfenapyr 36 sc @225ml/ha chlorantraniliprole 200 sc @150ml/ha lufenuron+profenofos 55ec @ 650ml/ha 14.08b 3.68ab 15.53ab 3.08a 4 lufenuron+profenofos 55ec @650ml/ha chlorfenapyr 36 sc @225ml/ha alphacypermethrin 100g/l @300ml/ha 14.15b 3.51abc 14.05b 2.42b 5 chlorpyriphos 48% ec @2l/ha lufenuron+profenofos 55ec @650ml/ha lambda-cyhalothrin 5% ec @480ml/ha 12.63b 3.39bc 10.5b 2.31bc 6 lambda-cyhalothrin 5% ec @480ml/ha lambda-cyhalothrin 5% ec @480ml/ha lambda-cyhalothrin 5% ec @480ml/ha 12.40bc 3.12c 10.13b 2.26bc 7 unsprayed unsprayed unsprayed 10.38c 2.56d 9.0b 1.91c lsd ( 0.05) 2.05 0.44 6.78 5.08 cv (%) 10.39 8.87 15.37 13.57 se 0.69 0.15 2.28 0.15 note: means followed by the same letter (s) within a column are not significantly different from each other at 5% level of significance. mailto:2.5ec@600ml/ha mailto:2.5ec@600ml/ha zemedkun et al. sequential application of insecticides for cotton bollworm management 49 4. discussion the present study indicated application of chlorantraniliprole 200sc and chlorfenapyr 36 sc resulted in a better control of h. armigera larva on cotton. the results is consistent with the findings of cordova et al. (2006) and bheemanna et al. (2008) who found that chlorantraniliprole 20 sc @40 g a.i. ha-1 effectively controlled h. armigera on cotton by causing impaired regulation, paralysis, and ultimately death of sensitive species. similarly, aslam et al. (2004) and perini et al. (2016) also reported that due to knockdown chemical nature, chlorfenapyr effectively controlled h. armigera. for the long time, year to year and repeated application within a season of lambda-cyhalothrin and deltamethrin had resulted effective for controlling of h. armigera in cotton. that lufenuron insect growh regulator insecticide also resulted in an effective control of the pest by forming abnormal new cuticle and death of the insect was earlier reported by gopal and tarikui (2014) and tarikul et al. (2015). confirming the results of this study, vittozzi et al. (2001) reported that profenophos insecticide toxicity can occur in two ways: inhibition of acetylcholine esterase, and cytotoxic effects on immune cells. sequential application of chlorantraniliprole, chlorfenapyr, profenofos insecticides resulted in the lowest h. armigera larvae population due to high controlling efficacy. however, the lowest controlling efficacy was from conventional insecticides lambdacyhalothrin applied in three sequences. the results this study revealed that sequential application of a mixture of insect growth regulator and organophosphate insecticides provided a good control of the h. armigera larva pest. the results confirmed that in both cropping seasons during the experiment, inclusion of deltamethrin in the rotation reduced the insecticide efficacy in controlling cotton bollworm. the results of this study agrees with the findings of salama et al. (2013) who reported that the sequential application of conventional insecticides in rotation with biocides, igrs, and anti-molting compounds provided a good average reduction in the larval population of cotton bollworms. similarly, rabia et al. (2016) suggested a rotational scheme of application of insecticides with different modes of action to reduce the onset of development insecticide resistance in h. armigera. many studies have evaluated the effects of insecticide mixtures in suppressing populations and damage of h. armigera insect pests (martin et al., 2003; hamed et al., 2006; nayak and daglish, 2007; borude et al., 2018). pesticide mixture has been recommended for use as a resistance management strategy based on the assumption that insects will not develop resistance to multiple modes of action simultaneously (warnock and cloyd, 2005). 5. conclusion the results of this study have revealed that application of deltamethrin and lambda-cyhalothrine reduced their efficacy for controlling helicoverpa armigera; thus, there is a need to replace them with the new insecticides chlorfenapyr for providing good control against h. armigera on cotton. application of insecticide with a different mode of action in rotations resulted in a significantly higher cotton yield than the convectional way of spraying lambda-cyhalothrin repeatedly. future studies are needed to monitor the level of insecticide resistance and design insecticide resistance management strategies. 6. acknowledgments the authors acknowledge the ethiopian institute of agricultural research for providing research facilities and financial supports for the study. 7. references abbott, w.s. 1925. a method of computing the effectiveness of an insecticide. journal of economic entomology, 18: 265–267. aslam, m., razaq m., rana, s. and faheem, m. 2004. efficacy of different insecticides against bollworms on cotton. journal of reseach science, 15(1): 17–22. bhardwaj, k., sharma, s., abrham, j. and sharma, p. 2020. natural bioactive products in sustainable agriculture. springe, 113–130. bheemanna, m., hosamani, a.c., sharanabasappa and patil, b.v. 2008. bioefficacy of new insecticide chlorantraniliprole 20 sc against bollworm in the cotton ecosystem. pestology, 32(10): 37–40. borude, b.s., bhalkare, s.k., undirwade, d.b. and rathod, p.k. 2018. ready mix insecticides for cotton bollworm complex. international journal of current microbiology and applied science, 6: 1974– 1984. cloyd, r.a. 2010. pesticide mixtures and rotations: are these viable resistance mitigation strategies? pest technology, 4(1): 14–18. cordova, d., benner, e.a., sacher, m.d., rauh, j.j., sopa, j.s., lahm, g.p., selby, t.p., stevenson, t.m., flexner, l. and gutteridge, s. 2006. anthranilic diamides: a new class of insecticides with a novel mode of action, ryanodine receptor activation. pesticide biochemistry and physiology, 84: 196–214. deguine, j.p., ferron, p. and russell, d. 2008. sustainable pest management for cotton production. a review. agronomy for sustainable development, 28(1): 113–137. eiar (ethiopian institute of agricultural research). 2016. national cotton research program strategy for fifteen years (2016-2030). developing national cotton commodity long term (15 years) research strategy consultative workshop by cotton research core team zemedkun et al. east african journal of sciences volume 15 (1) 41-50 50 members. october 24-29, 2016. addis ababa, ethiopia. pp. 26–33. ermias shonga, geremew terefe, zeraye mehari and mesfin wondafrash. 2009. pp. 93–116. in: abraham tadesse. 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(lepidoptera: noctuidae). pakistan journal of zoology, 38(1): 39–42. iar (institute of agricultural research). 1990. progress report of melka werer research center for the period 1988–1990 (unpublished). iar, addis ababa, ethiopia. muhmood, a. 2007. insecticide resistance mechanisms and their management in helicoverpa armigera (hübner) – a review. journal of agricultural research, 45(4): 319–335. martin, t., ochou, g.o., vaissayre, m. and fournier, d. 2003. organophosphorus insecticides synergize pyrethroids in the resistant strain of cotton bollworm helicoverpa armigera (hu¨bner) (lepidoptera: noctuidae) from west africa. journal of economic entomology, 96(2): 468–474. nayak, m.k. and daglish, g.j. 2007. combined treatments of spinosad and chlorpyrifos-methyl for management of resistant psocid pests (psocoptera: liposcelididae) of stored grain. pest management science, 63:104–109. perini, r.c., arnemann, a. j., melo, a.a., pes, p.m., valmorbida, i., beche, m. and guedes, c.j. 2016. how to control helicoverpa armigera on soybean in brazil? what we have learned since its detection. african journal of agricultural research, 11(16): 1426–1432. rabia, s., muhammad, r., muhammad, r. and muhammad, n. 2016. evaluating insecticide spray regimes to manage cotton leafhopper, amrasca devastans (distant): their impact on natural enemies, yield and fiber characteristics of transgenic bt cotton. pakistan journal of zoology, 48(3): 703–711. salama, m., abd el-mohsen, m.a., abd el-baki, b.a. and el-nagar, e.y. 2013. the efficiency of some insecticides sequence on cotton bollworms and histopathological effects of some biocides on pink bollworm larvae. egyptian journal of agricultural research, 91(2): 429–447. sas (statistical analysis software). 1999. statistical analysis systems sas/stat users guide version 8e cary nc: sas institute inc. usa. tarikul, i., gopal, s. and mokshead, a. 2015. efficient of luferon, a chitin synthesis inhibitor on the mortality of spodoptera litura (fabricius) under laboratory condition. journal of entomology and zoology studies, 3(3): 480–483. tsedeke abate. 1982. cotton pest problems and their control in ethiopia. proceedings of the symposium on cotton production under irrigation in ethiopia. october 1982, iar, melka werer, ethiopia. pp. 111–127. vittozzi, l., fabrizi, l., consigliko, e. and testai, e. 2001. mechanistic aspects of organo phosphorothionate toxicity in fish and humans. environmental entomology, 26(3): 125–129. waktole sori. 1996. management of cotton insect pests in ethiopia: a review. proceedings of integrating biological control and host plant resistance. cta/iar/iibc, addis ababa, ethiopia. pp. 224–252. warc (werer agricultural research center). 1998. progress report for the period january to december 1998 (unpublished). eiar, werer, ethiopia. warc (werer agricultural research center). 2015. progress report for the period january to december 1998 (unpublished). eiar, werer, ethiopia. warnock, d.f. and cloyd, r.a. 2005. effects of pesticide mixtures in controlling western flower thrips (thysanoptera: thripidae). journal of entomological science, 40: 54–66. wendmagen chekole and abere mnalku. 2012. selected physical and characterstics of soil of middle awash irrigated farm lands, ethiopia. journal of agriculture science, 22: 127–142. xiao, c., gregg, p., hu, w., yang, z. and zhang, z. 2002. the attraction of the cotton bollworm, helicoverpa armigera (hübner) (lepidoptera: noctuidae), to volatiles from wilted leaves of a non-host pant, pterocarya stenoptera. applied entomology and zoology, 37: 1–6. https://www.cabdirect.org/cabdirect/search/?q=au%3a%22rabia+saeed%22 https://www.cabdirect.org/cabdirect/search/?q=au%3a%22muhammad+razaq%22 https://www.cabdirect.org/cabdirect/search/?q=au%3a%22muhammad+rafiq%22 https://www.cabdirect.org/cabdirect/search/?q=au%3a%22muhammad+naveed%22 ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15 (2): 103-114 licensed under a creative commons *corresponding author: gezahegnabebe8@gmail.com attribution-noncommercial 4.0 international license. physiological races of colletotrichum lindemuthianum, the cause of bean anthracnose in major bean growing regions of southern and central ethiopia abebe gezahegn1*, alemayehu chala2, and getachew ayana3 1,3melkassa agricultural research center, p.o. box 436, adama, ethiopia 2hawassa university, p.o. box 05, hawassa, ethiopia abstract background: bean anthracnose (colletotrichum lindemuthianum (sacc. & magnus) briosi & cavara) is one of the major diseases of common bean (phaseolus vulgaris l.) in ethiopia causing up to a 63% yield loss. however, information regarding the race variability of the pathogen in ethiopia is limited. objectives: the current study was initiated with the objective of characterizing races of c. lindemuthianum prevailing in major bean producing areas in southern and central ethiopia. materials and methods: thirty isolates of c. lindemuthianum, collected from potential bean growing districts of damot gale, halaba special, melkassa, hawassa zuria, and boricha in 2017 were inoculated on to 12 differential cultivars in a greenhouse using a completely randomized design. results: the results revealed the presence of 17 physiological races (pathotypes) of the pathogen, of which only three were previously reported from ethiopia. race 9 was found to be the most dominant one across the surveyed areas. four races (2073 from halaba special, 2225 from damot gale, 2260 from melkassa, and hawassa zuria, and 3047 from boricha districts) were able to infect the highly resistant differential cultivar g2333, indicating that the ethiopian c. lindemuthianum populations might be composed of highly virulent races. the cultivars michelite, mexico 222, and pi 207262 showed the most susceptible reaction to the tested races, while no cultivar was immune to the pathogen races. the results have demonstrated the existence of highly variable isolates of c. lindemuthianum that cause bean anthracnose in ethiopia. conclusions: the ethiopian bean anthracnose pathogen (colletotrichum lindemuthianum) has high variability. the pathogen seems to be widely distributed in all studied bean growing areas with highly virulent as well as less virulent races. it is also suggested that the c. lindemuthianum population in ethiopia could possibly be composed of highly virulent races that can cause much damage even to resistant/tolerant germplasm. the results provides important useful insights into future breeding programs for developing host resistance against bean anthracnose in the country. identifying the race should continue using techniques that are more advanced and by including additional isolates across different agro-ecological settings in the country. keywords: colletotrichum lindemuthianum; differential cultivars; phaseolus vulgaris; physiological races; virulent 1. introduction bean anthracnose caused by colletotrichum lindemuthianum (sacc. & magnus) briosi & cavara, is one of the most important seed borne diseases of common bean (phaseolus vulgaris l.) in the world (amin mohammed, 2013; amin mohammed et al., 2014; fitsum sileshi et al., 2014). depending on the cultivar and environmental conditions, anthracnose infections can drastically reduce crop yields (perseguini et al., 2016). fernandez et al. (2000) reported that infection of susceptible cultivars, like mexican-142 and awash-1, under favorable environmental conditions leads to 100% grain yield loss. in africa, the disease is common in burundi, democratic republic of congo, ethiopia, kenya, rwanda, tanzania and uganda (batureine, 2009). in ethiopia, the disease is a major production constraint in potential bean-growing regions (fitsum sileshi et al., 2014), causing a yield loss of up to 63% (tesfaye beshir, 1997). colletotrichum lindemuthianum exists in many physiological forms in all bean-growing regions of the world and infects bean genotypes from both bean gene pools, i.e. andean and mesoamerican (mahuku and riascos, 2004). according to ciat (1997), the fungus is known to have races that vary across countries, regions, locations and varieties. the highest diversity and variation have been reported from latin america, which is the center of origin of common beans (pastorcorrales et al., 1995). east african regions are considered as the secondary center of diversity for common bean, and due to co-evolution of the c. lindemuthianum abebe et al. east african journal of sciences volume 15 (2): 103-114 104 pathogen and its host, the regions are expected to have a high variability of c. lindemuthianum (moses et al., 2016). the existence of a high pathogenic variability and emergence of new pathogen races results in continuous breakdown in host resistance (bigirimana and hofte, 2001). knowledge on race variability of the pathogen population is a prerequisite for developing durable resistance in bean varieties (batureine, 2009). coevolution of the pathogen and its host in the andean and mesoamerican gene pools provides a useful means of identifying appropriate sources of resistance, since common bean genotypes originating from one gene pool are more likely to express resistance to pathogenic races than another gene pool (allen et al., 1998; pastorcorrales, 2004). different race characterization has been carried out in africa and the rest of the world. for example (alzate marin et al., 2000 and mahuku and riascos, 2004) identified a total of 50 and 90 races of colletotrichum lindemuthianum pathotypes, respectively, in brazil between 1994 and 2002 from andean and mesoamerican bean varieties. to date about 1590 isolates of c. lindemuthianum inoculated on 12 bean differential cultivars have resulted in the identification of 182 races worldwide (padder et al., 2017). in africa, from the 12 isolates collected from the major bean-growing areas in burundi nine races were identified (bigirimana et al., 2000). on the other hand, out of the 50 isolates collected from potential bean agro ecological zones of tanzania, 42 races were identified (masunga et al., 2020). but in ethiopia, although some works have been done on c. lindemuthianum variability and the race identification, information is still limited and also the work was done long ago. in 1992, race studies were initiated and isolates characterized from different bean-growing regions in the country bako, ambo, ziway, awassa, areka, adami tulu, meki, jimma and alem tena and fifteen races of c. lindemuthianum were identified (tesfaye beshir, 2005). studies of pathogenic variation among 20 isolates of the anthracnose pathogen led to the identification of at least nine races (tesfaye beshir, 1995). tesfaye beshir (2003) identified eight races of c. lindemuthianum and compared them to six races brought from southern africa. however, for breeding anthracnose resistant varieties, studying and identifying the available races of c. lindemuthianum on major bean growing areas of the country, which is helpful in planning suitable breeding strategies for varieties with durable resistance over time and space is very important. therefore, this research was aimed at studying variability in c. lindemuthianum and identifying races of the pathogen occurring in major bean growing regions in southern and central ethiopia. 2. materials and methods 2.1. disease survey a field survey was conducted in 2017 main cropping season to isolate colletotrichum lindemuthianum in selected districts of oromia national regional state (central) and southern nations, nationalities, and people’s region (snnpr) (southern) ethiopia. based on production potential and importance of bean anthracnose, five representative districts, namely damot gale, halaba special, melkassa, hawassa zuria, and boricha were selected for the study (figure 1). the surveyed areas have elevations ranging between 1436 and 1958 meters above sea level. during the survey, two to three farmers’ fields were randomly selected from each district. in each sample field, five quadrats (each 1 m2) were sampled and disease incidence and severity were assessed for every quadrat by moving diagonally across each field from one end to the other in an ‘x’ pattern. from each quadrat (plot), the number of plants assessed and number of plants with anthracnose symptom were counted. disease incidence was recorded as the percentage of plants showing anthracnose symptoms in each quadrat, and the averages of the five quadrats were calculated for each field. disease incidence (%) = number of anthracnose infected plant(s)per quadrat total number of plants assessed per quadrat x 100 severity of bean anthracnose was recorded on the symptom of the disease on the leaves based on ciat (1987) standard system for evaluation of bean anthracnose scoring scales (table 1). abebe et al. physiological races of bean anthracnose 105 table 1. symptom evaluation of common bean anthracnose severity scale according to ciat (1987). disease scale description of common bean plant parts affected 1 no visible disease symptom 3 presence of very few and small lesions, mostly on the primary vein of the leaf's lower side or on the pod, that covers approximately 1% of the surface area 5 presence of several small lesions on the petiole or on the primary and secondary veins of the leaf's lower side. on the pods, small (less than 2 mm diameter) round lesions, with or without reduced sporulation, cover approximately 5% of the pod surface areas 7 presence of numerous enlarged lesions on the lower side of the leaf. necrotic lesions can also be observed on the upper leaf surface and on petioles. on the pods the presence of medium sized (>2 mm in diameter) lesions are evident but also some small and larger lesions generally with sporulation and that cover approximately 10% of pod surface area may be found 9 severe necrosis on 25% or more of the plant tissue is evident as a result of lesions on the leaves, petioles, stem, branches, and even on the growing point which often results in death of the plant tissues. the presence of numerous, large, sporulating and sunken cankers can result in pod malformation, low seed number, and death of the pod figure 1. map showing survey districts for bean anthracnose in oromia (central) and snnp region (southern) ethiopia. 2.2. sample collection sample collection was conducted at flowering and grain filling stage. in each location, samples depicting typical bean anthracnose symptoms were randomly considered, and from each identified representative plants, three leaves were collected. the leaves collected were immediately wrapped up in paper towels to blot excess moisture and placed in paper bags after labeling with necessary information in pencil. finally, specimens were kept in a refrigerator at 4 oc until processing for analyzing the races of the pathogen. 2.3. isolation of the pathogen isolation of the pathogen was conducted at melkassa agricultural research center (marc) plant pathology laboratory. leaf samples were washed under running tap water and 2–5 mm long leaf pieces or patches were cut using a pair of scissors that was surface-sterilized with 2.5% sodium hypochlorite (naocl) solution for 2– 3 minutes and rinsed three times with sterile distilled water. since collected samples could possibly carry more than one strain of the pathogen or even more pathogens, abebe et al. east african journal of sciences volume 15 (2): 103-114 106 efforts were made to spatially resolute a spot with the typical anthracnose symptom from a single leaf, and then pieces were cut out to maintain the genetic purity of c. lindemuthianum isolates. then, the pieces were placed on sterilized paper towel for 5–10 minutes; five such pieces were aseptically transferred into a 9 cm petri dish with potato dextrose agar (pda). the cultures were incubated for 10 days at 20 °c under continuous fluorescent light. sub-culturing was done by taking a 3 mm mycilial plug from the pda, which was visually free from any contamination, and transferring it into new petri dishes containing fresh pda. then continuous sub-culturing was made until pure cultures with no contamination were obtained (bean pathogens practical guide for laboratory). finally, 30 isolates were purified and obtained from the survey areas for race identification. 2.4. inoculum preparation for race identification inoculum was prepared following the methods described by batureine (2009). two-week-old pure cultures were flooded with 50 ml of sterile distilled water and the spores scraped-off using a fine brush. flooding was repeated three times, each time using fresh sterile distilled water to get most of the conidia from the culture. then the suspension was poured into a beaker and mixed thoroughly. spore suspensions from all cultures of the same isolate were mixed and passed through double layer cheesecloth to remove fragments of mycelia and culture medium. the standard concentration of the spore suspension for each obtained isolate was adjusted to 1.2x106 spores per ml of sterile distilled water using hemocytometer (batureine, 2009). one drop of tween 20 was added per 100 ml spore suspension as surfactant and mixed thoroughly before inoculation. 2.5. planting common bean differentials differentials are sets of plant cultivars used to define race/pathotypes of pathogens based on known susceptible and resistant reactions. common bean seeds of 12 differential cultivars (table 2) obtained from the international center for tropical agriculture (ciat) were surface-sterilized with 0.1% naocl solution for three minutes, washed or rinsed thoroughly with sterile distilled water and dried at room temperature (25 + 2 oc). then the seeds were sown in plastic pot filled with 3 kg mix of sun-dried sterile top soil, manure and sand in 2:1:1 ratio, respectively, and pots placed in greenhouse. five seeds were sown per pot in completely randomized design, and each plant was considered as a replicate for each common bean differential cultivars and for each isolate of the pathogen. 2.6. inoculation fourteen-day-old common bean seedlings were used for inoculation. all the 12 differential cultivars were inoculated separately with the prepared separate isolate suspension using a hand sprayer on both the abaxial and adaxial surfaces of the leaves until suspension runoff at a time. a control (plants inoculated with sterile distilled water) was included for each set of the differentials inoculated with an isolate. in order to maintain the relative humidity of approximately 95% for the infection to take place, each inoculated plants were covered with transparent polythene sheets for five days after inoculation. after removal of polythene sheet, pots were kept in the greenhouse and maintained at the temperatures of 18–33 oc and relative humidity ranging from 72 to 95%. 2.7. race analysis the reaction [susceptible reaction (+) and resistant reaction (-)] of each common bean differential cultivar to each isolate was assessed 15 days after inoculation, i,e. 30 days after planting. for the purpose of consistency, only the primary leaves of each plant were evaluated. after evaluation of all differential cultivars, race identification was done as the sum of binary numbers of all differential cultivars showing susceptible reaction to the particular isolate. a binary number is equal to 2n, where n is equivalent to the place of the cultivar within the differential series order as presented in table 2. the sum of all binary numbers of cultivars with susceptible reactions (i.e., y = 2n + 2(n+1) + 2(n+2) +……. + 2(n+11); where n = 0) gives a specific race number or name (y) (kelly and vallejo, 2004). abebe et al. physiological races of bean anthracnose 107 table 2. standard differential cultivars of common bean used to characterize colletotrichum lindemuthianum, their binary codes, resistance genes, growth habit and gene pool. differential cultivar seed type notation binary code resistance gene gene pool growth habit michelite s 0 1 co-11 ma ii mdrk l 1 2 co-1 a i perry marrow l 2 4 co-13 a ii cornell 49-242 s 3 8 co-2 ma ii widusa l 4 16 co-15 a i kaboon l 5 32 co-12 a ii mexico 222 s 6 64 co-3 ma i pi 207262 s 7 128 co-43, co-9 ma iii to s 8 256 co-4 ma i tu s 9 512 co-5 ma iii ab 136 s 10 1024 co-6, co-8 ma iv g2333 s 11 2048 co-42, co-52, co-7 ma iv note: s = small seeded; l = large seeded; ma = middle american; a = andean; i = determinate; ii = indeterminate bush; iii = indeterminate bush with weak main stem and prostrate branches; and iv = indeterminate climbing habit (awale et al., 2007). abebe et al. east african journal of sciences volume 15 (2): 103-114 108 3. results and discussions 3.1. disease survey bean anthracnose incidence in the study areas ranged from 33 to 67% (figure 2). the highest anthracnose incidence (67%) was recorded for hawassa zuria and boricha districts, followed by damot gale (59%), while the lowest (33%) was recorded for melkassa. the results are in contrast to the finding of habtu assefa et al. (1996) who reported high level of bean anthracnose in the rift valley region including melkassa and low level of bean anthracnose in sidama areas where hawassa zuria is located. the change in climate and the change in the type of varieties produced in the area may have led to such deviations in bean anthracnose incidence. the mean anthracnose severity scores across the surveyed areas ranged from 2.5 to 6.0. the highest (6.0) severity was recorded for damot gale and boricha districts and the lowest (2.5) was recorded for melkassa. these results are not in accord with the result of tesfaye beshir (2005) who reported higher anthracnose severity in the western zone and rift valley areas of the country, suggesting a possible shift in bean anthracnose intensity across the country. seed born nature of the disease (genchev et al., 2010) and uncontrolled exchange of common bean seeds for planting across the country might lead to such deviations in the incidence and severity of bean anthracnose. figure 2. incidence and severity of common bean anthracnose in the surveyed areas, southern and central ethiopia. 3.2. race analysis in the study area, the reactions of bean differential cultivars to the selected isolates varied. out of the 30 isolates of c. lindemuthianum collected, a total of 17 physiological races (pathotypes) were identified based on race designation (table 4), which was reported as an indicator of the presence of variability of the pathogen (batureine, 2009). out of 17 races identified, only three races, races 128, 898 and 1011 were earlier reported from ziway, bako and areka district in ethiopia, respectively (tesfaye beshir, 2005). race 9, which was identified from boricha, hawassa and halaba districts, was the most frequently isolated physiological race, followed by the races 272, 1011 and 2260. similarly, it was also reported to be the most widespread race in argentina (ansari et al., 2004). moreover, the same authors indicated that race 9 was isolated from four different countries. on the other hand, gonçalves et al. (2008) stated that race 73 was the most common and widespread race in santa catarina state in brazil. geographically, four (385, 3047, 9 and 587), two (2260 and 272), 12 (272, 321, 9, 1172, 898, 128, 465, 73, 1250, 34, 1011 and 2260), two (2225 and 1011), and two (2073 and 9) races were identified from boricha, melkassa, hawassa, damot gale, and halaba areas, respectively (table 3). this suggests an abundance of c. lindemuthianum race variability in the southern and central bean producing regions in the country. the differences among the pathogen populations in different areas might reflect the differences in the agricultural practices employed and common bean germplasm used, which would affect the selection and adaptation processes in the different agro-ecologies (batureine, 2009). of the 17 c. lindemuthianum races identified, four races 2073, 2225, 2260 and 3047 were able to infect the highly resistant differential cultivar g2333. susceptibility of this cultivar to the isolates of c. lindemuthianum has been rarely reported (mahuku et al., 2002). thus, the result 0 10 20 30 40 50 60 70 80 damot gale halaba melkassa hawassa boricha in c id e n c e a n d s e v e ri ty ( % ) surveyed areas incidence severity abebe et al. physiological races of bean anthracnose 109 strongly suggests that c. lindemuthianum populations in ethiopia could possibly be composed of highly virulent races that may cause much damage even to resistant/tolerant bean cultivars. beside the differential cultivar g2333, race 3047 (isolate from boricha) also successfully infected the differential cultivars tu, to, pi 207262, mexico 222, kaboon, perry marrow, mdrk and michelite. hence, this c. lindemuthianum race is a very aggressive isolate in the area. furthermore, race 2260 managed to break the resistance of the differential cultivars perry marrow, widusa, mexico 222 and pi 207262. while race 2225 managed to break the resistance of the differential cultivars michelite, widusa, kaboon and pi 207262, and race 2073 managed to break the resistance of the differential cultivars michelite, cornell 49-242 and widusa (table 4). table 3. the number of isolates and races of colletotrichum lindemuthianum identified in each district using bean anthracnose differentials. region (zone) district no. of isolates identified races southern nations, nationalities and people’s region (snnpr) boricha 5 4 hawassa zuria 19 12 damot gale 2 2 halaba 2 2 oromia national regional state melkassa 2 2 none of the differential cultivars was resistant to all of the isolates tested. nevertheless, the differential cultivar ab 136 was a relatively more resistant cultivar than the other, considering the number of races, only two races, i.e. 1172 and 1250 that infected it. this observation is similar with findings of sicard et al. (1997) and gonzalez et al. (1998) who reported that the differential cultivar ab 136, containing resistance genes co-6 and co-8 as resistant to many isolates of c. lindemuthianum originating from different parts of the world. the differential cultivars perry marrow, g 2333 and tu were susceptible to three, four and four races, respectively, and ranked second and third most resistant cultivars to the pathogen races in the current experiment (figure 3). a similar result was reported by cláudia et al. (2002), where the cultivars ab 136 and g 2333 were found resistant to races collected from paraná state of brazil. likewise, the differential cultivar tu also reported to be susceptible to four isolates of c. lindemuthianum in another study (ansari et al., 2004). on the other hand, the differential cultivars michelite and pi 207262 were found to be the most susceptible differential cultivars showing susceptible reaction to 59% of all c. lindemuthianum races, followed by mexico 222, to and widus, which were susceptible to 53%, 41% and 41% of all collected races, respectively (figure 3). consistent with the results of this study, cláudia et al. (2002) and ansari et al. (2004) reported that michelite, mexico 222, widusa and cornell 49242 cultivars were the most susceptible differential cultivars. the differential cultivars michelite and mexico 222 showed susceptible reactions to all of the 10 isolates collected from grosso state, brazil (gonçalves et al., 2010). gonzaz (2016) also reported that, the bean differential cultivar michelite was susceptible to all c. lindemuthianum isolates collected from arumeru, karatu, mbulu and babati rural areas in tanzania. abebe et al. east african journal of sciences volume 15 (2): 103-114 110 table 4. reaction of 12 common bean differential cultivars to colletotrichum lindemuthianum isolates under greenhouse conditions. isolates common bean differential cultivars race name michelite mdrk perry marrow cornell 49242 widusa kaboon mexico 222 pi 207262 to tu ab 136 g 2333 boricha205 + + 9 block 2(2) + + 9 halaba p-2 + + 9 hrc 318 + + 34 hrc 8 + + 34 hrc 308 + + 34 hrc 9 + + + 73 hrc 12 + + + 73 hrc 315 + 128 seed multi + + 272 block 1(2) + + 272 block 1(3) + + + 321 block 1(1) + + + 321 boricha207(1) + + + 385 boricha207(3) + + + 385 hrc 314 + + + + + 465 hrc 319 + + + + + 465 boricha204 + + + + + 587 hrc 305 + + + + 898 wolaita p-7 + + + + + + + + 1011 hrc 6 + + + + + + + + 1011 block 2(3) + + + + 1172 hrc 7 + + + + + 1250 hrc 1 + + + + + 1250 hrc 310 + + + + + 1250 halaba p-3 + + + + 2073 wolaita p-6 + + + + + 2225 kechachule 2 + + + + + 2260 hrc 2 + + + + + 2260 boricha207(2) + + + + + + + + + 3047 note: (+) = susceptible reaction, and (-) = resistant reaction. abebe et al. physiological races of bean anthracnose 111 figure 3. reaction of 12 common bean differential cultivars to 17 races of colletotrichum lindemuthianum tested under greenhouse conditions. of the 17 c. lindemuthianum races identified in the current work, race 3047 and race 1011 were the most ‘cosmopolitan’ races, infecting nine and eight differential cultivars, respectively, whereas race 9, 34 and 128 were ‘narrow host ranged’, infecting only two cultivars, out of the total 12 differential cultivars (figure 4). figure 4. virulence of races of colletotrichum lindemuthianum collected from south and central ethiopia as evaluated using common bean differential cultivars under greenhouse conditions. with reference to bean gene pool, among the 17 identified races, 11 races (272, 465, 587, 898, 1011, 1172, 1250, 2073, 2225, 2260 and 3047) were pathogenic to the common bean differential cultivars having gene pool from both mesoamerican and andean origin. it is common to see races infecting differential cultivars having both gene pools as reported by gonzaz (2016). race 34 was pathogenic only to the differential cultivars from andean gene pool, whereas races 9, 73, 128, 321 and 385 were pathogenic only to mesoamerican gene pool. in line with this result, race 73, which infected only the mesoamerican origin in this study, was also shown to be pathogenic to the differential cultivars from mesoamerican origin (cláudia et al., 2002). most of the isolates collected from argentina and central america were predominantly pathogenic to the mesoamerican cultivars, while isolates collected from africa, europe, the dominican republic and south america showed a higher frequency of pathogenicity to the andean 0 2 4 6 8 10 12 n u m b e r o f ra c e s common bean differential cultivars 0 1 2 3 4 5 6 7 8 9 10 128 34 9 385 321 272 73 1172 2073 898 587 2260 2225 1250 465 1011 3047 n o . d if fe re n ti al s in fe c te d identified races abebe et al. east african journal of sciences volume 15 (2): 103-114 112 cultivars than to the mesoamerican differential cultivars (ansari et al., 2004). 4. conclusions the results of the study have demonstrated that the ethiopian bean anthracnose pathogen (colletotrichum lindemuthianum) has high variability in major bean growing areas of south and central ethiopia. the pathogen seems to be widely distributed in all studied bean growing areas with highly virulent as well as less virulent races. the results also suggest that the c. lindemuthianum population in ethiopia could possibly be composed of highly virulent races that can cause much damage even to resistant/tolerant germplasm. the differential cultivar ab 136 showed a relative high resistance as it was found to be susceptible only to two races. however, michelite and pi 207262 were found to be the most susceptible differential cultivars, both showing susceptible reactions to 10 races. race 34 was the only race that was pathogenic only to differential cultivars from andean gene pool, whereas races 9, 73, 128, 321 and 385 were pathogenic only to differential cultivars from mesoamerican gene pool. it is suggested that the ethiopian population of colletotrichum lindemuthianum should be regularly monitored for emergence of new races, and race identification studies need to be continued with advanced techniques like molecular method by including more isolates across different agro-ecologies of ethiopia. 5. acknowledgements authors thank the ethiopian institute of agricultural research for financially supporting the study. we also acknowledge dr. berhanu amsalu for facilitating acquisition of the different differential cultivars of common bean from the international centre for tropical agriculture (ciat). we further extend our thanks to ciat for the supply of initial seeds. 6. references allen, d.j., buruchara, r.a. and smithson, j.b. 1998. diseases of common bean. the pathology of food and pasture legumes. cab international. pp. 179–265. alzate-marin a.l., menarim h., josé m.c., everaldo g.b. and maurilio a.m. 2000. identification of a rapd marker linked to the co-6 anthracnose resistant gene in common bean cultivar ab 136. genetics and molecular biology, 23(3): 633–637. amin mohammed. 2013. an overview of distribution, biology and the management of common bean anthracnose. journal of plant pathology and microbiology, 4: 1–4. amin mohammed, amare ayalew and nigusie dechassa. 2014. effect of integrated management of bean anthracnose (colletotrichum lindemuthianum) through soil solarization and fungicide application on epidemics of the disease and seed health in hararghe highlands, ethiopia. journal of science and sustainable development, 4: 182– 182. ansari, k.i., palacios, n., araya, c., langin, t., egan, d. and doohan, f.m. 2004. pathogenic and genetic variability among colletotrichum lindemuthianum isolates of different geographic origins. plant pathology, 53: 635–642. batureine, m.j. 2009. diversity of colletotrichum lindemuthianum and reaction of common bean germplasm to anthracnose disease. msc. thesis, makerere university, uganda. bigirimana, j., fontaine, r. and höfte, m. 2000. bean anthracnose: virulence of colletotrichum lindemuthianum isolates from burundi, central africa. plant disease, 84(4): 491. http://hdl.handle.net/1854/lu-133099. bigirimana, j. and hofte, m. 2001. bean anthracnose: inoculation methods and influence of plant stage on resistance of phaseolus vulgaris cultivars. journal of phytopathology, 149: 403–408. ciat (international center for tropical agriculture). 1997. bean program annual report 1995. working document no. 163. centro internacional de agriculture tropical, cali, colombia. cláudia, t., maria celeste, g.v., pedro soares, v.f., william mário de, c.n. and joão batista, v. 2002. characterization of colletotrichum lindemuthianum races in paraná state, brazil. crop breeding and applied biotechnology, 2(1): 55–60. fernandez, m., casares, a., rodr´ıguez, r. and fueyo, m. 2000. bean germplasm evaluation for anthracnose resistance and characterization of agronomic traits: a new physiological strain of colletotrichum lindemuthianum infecting phaseolus vulgaris l. in spain. euphytica, 114: 143–149. fitsum sileshi, amin mohammed, thangavel, s. and mulugeta negeri. 2014. field management of anthracnose (colletotrichum lindemuthianum) in common bean through foliar spray fungicides and seed treatment bioagents. science, technology and arts research journal, 3(2): 19–25. genchev, d., christova, p., kiryakov, i., beleva, m. and batchvarova, r. 2010. breeding of common bean for resistance to the physiological races of anthracnose identified in bulgaria. biotechnology, 24(2): 1814–1823. gonçalves-vidigal, m.c., thomazella, c., elias, h.t. and vidigal filho, p.s. 2008. characterization of http://hdl.handle.net/1854/lu-133099 abebe et al. physiological races of bean anthracnose 113 colletotrichum lindemuthianum isolates using differential cultivars of common bean in santa catarina state, brazil. department of agronomy, university of maring, brazil 43–44. gonçalves-vîdigal, m.c., nunes, m.p.b.p., cruz, a.s., alves, m.a., sousa, l.l. and vidigal filho, p.s. 2010. characterization of colletotrichum lindemuthianum isolates from matogrosso state, brazil. usda publications, reports of bean improvement cooperative and national dry bean council research conference. http://handle.nal.usda.gov/10113/ind442070 99. gonzalez, m., rodriguez, r., zavala, m.e., jacobo, j.l., hernandez, f., acosta, j., martinez, o. and simpson, j. 1998. characterization of mexican isolates of colletotrichum lindemuthianum by using differential cultivars and molecular markers. journal of phytopathology, 88: 292–299. gonzaz, k.k. 2016. identification of colletotrichum lindemuthianum and introgression of its resistance gene(s) to common bean (phaseolus vulgaris l.) adapted in tanzania. msc. thesis. sokoine university of agriculture, morogoro, tanzania. habtu assefa, sachet, i. and zadoks, j.c. 1996. a survey of cropping practices and foliar diseases of common beans in ethiopia. crop protection, 15(2): 179–186. kelly, j.d. and vallejo, v.a. 2004. a comprehensive review of the major genes conditioning resistance to anthracnose in common bean. hortscience, 39: 1196–1207. mahuku, s.g., jara, c.e., cajiao, c. and beebe, s. 2002. sources of resistance to colletotrichum lindemuthianum in the secondary gene pool of phaseolus vulgaris and in crosses of primary and secondary gene pools. plant disease, 86: 1383– 1387. mahuku, s.g. and riascos, j.j. 2004. virulence and molecular diversity within colletotrichum lindemuthianum isolates from andean and mesoamerican bean varieties and regions. european journal of plant pathology, 110: 253–263. masunga m., nchimbi-msolla s., robert m. and luseko a. 2020. races of colletotrichum lindemuthianum (sacc. & magnus) briosi & cavara in major bean growing regions in tanzania. african journal of plant science, 4(8): 308–314 moses, j.k., aston, e., vincent, k., stanley, t.n., pamela, p., clare, m., and phinehas, t. 2016. pathogenic variation of colletotrichum lindemuthianum causing anthracnose of beans (phaseolus vulgaris) in uganda. international journal of phytopathology, 05(03): 89–98. padder b.a., sharma p.n., awale h.e. and kelly j.d. 2017. colletotrichum lindemuthianum, the causal agent of bean anthracnose (offered review). journal of plant pathology, 99(2): 317–330. pastor-corrales, m.a., otoya, m.m. and molina, a. 1995. resistance to colletotrichum lindemuthianum isolates from middle america and andean south america in different common bean races. plant disease, 79: 63–67. pastor-corrales, m.a. 2004. review of co-evolution studies between pathogens and their common bean hosts: implication for the development of disease-resistant beans. annual report of bean improvement cooperative 47: 67–68. perseguini, j.m.k.c., oblessuc, p.r., rosa, j.r.b.f., gomes, k.a., chiorato, a.f. and carbonell, s.a.m. 2016. genome-wide association studies of anthracnose and angular leaf spot resistance in common bean (phaseolus vulgaris l.). plos one, 11(3): e0150506. sicard, d., michalakis, y., dron, m. and neema, c. 1997. genetic diversity and pathogenic variation of colletotrichum lindemuthianum in the three centers of diversity of its host phaseolus vulgaris. journal of phytopathology, 87: 807–813. tesfaye beshir. 1995. studies on the importance, pathogenic variation and management of bean anthracnose in ethiopia. ciat african workshop series (ciat); no. 37, pp. 33–43. tesfaye beshir. 1997. loss assessment study on haricot bean due to anthracnose. pest management journal of ethiopia, 1: 69–72. tesfaye beshir. 2005. colletotrichum lindemuthianum on beans in ethiopia. geographical distribution, importance, pathogenic variation, and management. pp. 176-181. in: pabra millennium workshop, 2001, arusha, tanzania. https://naldc.nal.usda.gov/?f%5bcollection%5d%5b%5d=reports+of+bean+improvement+cooperative+and+national+dry+bean+council+research+conference https://naldc.nal.usda.gov/?f%5bcollection%5d%5b%5d=reports+of+bean+improvement+cooperative+and+national+dry+bean+council+research+conference https://naldc.nal.usda.gov/?f%5bcollection%5d%5b%5d=reports+of+bean+improvement+cooperative+and+national+dry+bean+council+research+conference http://handle.nal.usda.gov/10113/ind44207099 http://handle.nal.usda.gov/10113/ind44207099 abebe et al. east african journal of sciences volume 15 (2): 103-114 114 ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15 (1) 71-78 licensed under a creative commons *corresponding author: getademe12@gmail.com attribution-noncommercial 4.0 international license. evaluation of desho (pennisetum pedicellatum) grass varieties for dry matter yield and chemical composition under irrigation in two districts of south omo zone, southwestern ethiopia denbela hidosa and demerew getaneh* livestock research directorate, jinka agricultural research center, p.o. box, 96, jinka, ethiopia abstract background: productivity and reproductive performances of livestock in ethiopia is low mainly due to scarcity and quality of feed. the desho grass is indigenous to ethiopia and belongs to the family poaceae and has high biomass production potential that could be used to tackle the problem of scarcity and quality of feed. objectives: this study was initiated to evaluate dry matter yield and chemical composition of four desho grass varieties grown in irrigated lowland of dassench and hamer districts of south omo zone in southwestern ethiopia. material and methods: the sermemiret kebele from dassench district and eribore kebele from hamer district were selected for a participatory on-farm experimental trial with active involvements of district pastoral office experts and kebele development agents. four desho grass varieties, namely, areka-dzf#590, kulumisa-dzf#590, kindokisha-dzf#591 and areka local were evaluated in a randomized complete block design with three replications per variety. data on dry matter yield (dmy), cutting height, number of tillers per plant (ntpp) and leaf to stem ratio (ltsr) were analyzed using the generalized linear model (glm) procedures of sas. results: the highest (p < 0.05) dry matter yield (35.09 t ha-1) and crude protein (cp) (129.50g kg-1, dm) were recorded for areka-dzf#590 whereas the lowest dry matter yield (16.96 t ha-1) and cp (90.60g kg-1, dm) were obtained from areka local check. conclusion and implication: we conclude that areka-dzf#590 desho grass variety was found to be the highest in dry matter and crude protein production. pastoralists, agro-pastoralists, and farmers in the area could enhance feed availability for increased livestock production. keywords: acid detergent fiber; crude protein; cutting height; neutral detergent fiber; number of tillers per plant 1. introduction ethiopia has the largest livestock population in africa possessing 61 million cattle, 33.02 million sheep, 38.96 million goats, 1.93 million horses, 9.66 million donkeys, 0.37 million mules, camels 1.76 million and 59.42 million poultry population (csa, 2018/19 ). however, the overall production and productivity of livestock in ethiopia are generally very low due to many factors (fao, 2018). the poor feed quality and inadequate feed supply especially during the dry season are the top urgent factors that seriously reduce livestock production (fao, 2018). likewise, in the study districts, the livestock feeding system is extensively based on natural pasture (denbela hidosa et al., 2017; berhanu tekelyohannes et al., 2017). it is obvious that the natural pasture-based livestock feeding system is greatly influenced by feed supply and nutritional dynamics of range forages (hidosa and tesfaye, 2018). moreover, these feed resources could not satisfy the nutritional requirement of animals particularly in the dry seasons with the supply being inconsistently distributed over the seasons in the study districts. furthermore, feeds from natural pasture are characterized by high fiber (>55%) and low crude protein (cp) (< 7%) (diriba geleti et al., 2014). as a result, the total dry matter intakes are limited and barely satisfy even the maintenance requirements of animals. this triggers high mortality, longer calving intervals and substantial weight loss of livestock (denbela hidosa et al., 2017; berhanu tekelyohannes et al., 2017; hidosa and tesfaye, 2018; admasu teferi et al., 2010). therefore, testing and identifying adaptable forage species to improve natural pasturebased feeding system is the only way out to overcome the problem of feed shortage in the study districts (denbela hidosa et al., 2017; shapiro et al., 2015). desho (pennisetum pedicellatum) grass is an indigenous perennial grass of ethiopia belonging to the family poaceae. it has an extensive root system that well anchors the soil with high biomass production potential (leta gerba et al., 2013). the previously reported dry matter yields results for different varieties of this grass under irrigation were found to be 28.35, 26.52, 23.37 and 21.95 tons/hectare for areka-dzf#590, kulumisa-dzf#592, kindokishamailto:getademe12@gmail.com denbela and demerew east african journal of sciences volume 15 (1) 71-78 72 dzf#589 and kindokisha-dzf591 respectively (tekalegn yirgu et al., 2017). moreover, gadisa birmaduma et al. (2019) reported dry matter yields of 28.74, 26.14 and 23.59 ton/hectare for arekadzf#590, kulumisa-dzf#592 and kindokishadzf#591 varieties, respectively under rain fed condition. in addition, desho grass is currently being utilized as a means of soil conservation practices, rehabilitation of degraded land, as animal feeds as well as provision of a small business opportunity for the people in the country (foa, 2010; shiferaw abebe et al., 2011; leta gerba et al., 2013; yakob getahun et al. 2015; bimrew asmare et al, 2016; worku bedeka et al., 2017). pertaining to the feeding value of desho grass used as a basal diet, an increasing proportion of the hay from 0 to 100% for washera lambs supplemented with a concentrate mixture showed improvement in total dry matter intake, nutrient digestibility and average daily weight gain performances as compared to sheep fed on pasture hay as basal diet (bimrew asmare et al., 2016). however, different desho grass varieties have not been evaluated for forage dry matter yield and their chemical composition in irrigated lowland areas in south omo zone. therefore, the current study was initiated with the objectives of evaluating dry matter yield and chemical composition of four desho grass varieties grown under irrigation in dassench and hamer districts in south omo zone. 2. material and methods 2.1. description of study area this study was conducted in agro-pastoral areas of the hamer and dassench districts of south omo zone. dassench district is situated at a geographical location of 5014' “0”n latitude, 36044' 01”e longitude with an elevation range of 350 to 900m above sea level and an average temperatures ranging from 25 to 40oc. the annual rainfall of the district ranged from 350 to 600mm having a bimodal rainfall with erratic distribution and soil type is silty alluvial. according to the population projections for 2016/17 based on the population and housing census conducted in 2007 (central statistical agency, 2008), the dassench district has a total human population of 70, 133 and whereas, the population of livestock are estimated to be 1, 014, 403 cattle, 753, 568 sheep, 1, 013971 goats, 23, 412 poultry and 17, 228 donkeys. according to the estimate of csa (2010), the total population of hamer district is 79, 419 and the population is composed of three ethnic groups. these are hamer, erborie and kara with a population of 54,583 (81.4 %), 10,333 (15.4%) and 2,129 (3.2%), respectively. annual rainfall is an average of 764 mm per annum. the climate of the district is a mix of dry woyina dega (8%), dry kola (54%), semi dry kola (37.5%) and desert (0.5%). the highest temperature in the district ranges between 32 oc to 38 oc and while the lowest temperature ranges between 290c to 310c. livestock production is the main stay of the majority of the hamer district and there are about 324,000 cattle, 714,000 goats and 332,000 sheep (sofedb, 2014). 2.2. experimental site selection and preparation based on availability and accessibility of irrigation schemes, the sermemiret kebele (lowest administrative sub-unit) from dassench and eribore kebele from hamer district were selected for onfarm experimental trials after communication with livestock and fisher resource development offices of the two districts. the land ploughed, disked, harrowed and ridges by using tractor and corrected by labors. 2.3. experimental design and treatments in the current study, a randomized completed block design in factorial arrangement having two locations and four varieties level with three replications per variety was used to evaluate the desho grass varieties. a total of 12 plots were used in the experiment with three replications in which each of the plots having an area of a 4m x 3m = (12 m2). each plot had 4 rows with the spacing between rows and plants within a row being 1meter and 0.5 m, respectively (denbela hidosa et al., 2020). the spacing between plots was 1 meter and the total area of the experimental site was 13 x 16 m (208 m2). the three desho grass varieties; areka-dzf#590, kulumisadzf#590 and kindokisha-dzf#591 were collected from debre zeit agricultural research center, whereas one areka local variety obtained from jinka agricultural research center. the planting materials were the root splits which were planted without fertilizer application neither at planting nor in the growing period. furrow irrigation method was used with all plots being irrigated uniformly after a threeday interval. 2.4. data collection and measurement the agronomic data such as cutting height above ground, leaf to stem ratio (ltsr) and number of tillers per plant were recorded at the age of 65 days after planting by harvesting the two middle rows using sickle. fresh samples were recorded in the field immediately after harvest using spring balance. fivehundred-gram sample per plot was brought to jinka agricultural research center. samples were chopped into pieces and 300-gram sub-sample was taken to be dried in an oven set at a temperature of 105°c for 24 hours. dry matter yield was determined using the following formula described by james et al. (2008). dry matter yield (t/ha) = tfw x ( dwss ha x fwss) x 100; where, tfw = total fresh weight kg/plot; dwss = dry weight of sub-sample in grams; fwss = fresh weight of sub-sample in grams, ha = harvest plot area in square meters and 10 is a constant for conversion of yields in kg/m2 to t/ha. cutting height above ground was measured from the ground level to the tip of five randomly selected plants per plot using a steel tape. to determine the fresh weight of leaf to stem ratios, samples were denbela and demerew dry matter yield and chemical composition of desho grass 73 categorized into leaf and stem first and then the weights of each component was measured separately. the samples were oven dried for 24 hours at a temperature of 105°c and separately weighed to estimate the proportions of these parts. accordingly, the leaf to stem ratio (ltsr) was estimated based on the dry matter of each component. 2.5. chemical analysis the laboratory analysis was done at debre birhan agricultural research center, ethiopia. three forage sample of each variety was allowed to be oven dried set at a temperature of 65°c for 48 hours and ground to pass through a 1mm sieve size for chemical analysis (aoac, 1990). dry mater yield (dmy), crude protein (cp) and ash were analyzed according to the procedures of (aoac, 1990). the neutral detergent fiber (ndf) values were calculated using the procedure of van soest et al. (1991) and whereas the acid detergent fiber (adf) value was analyzed using the procedures described by van soest and robert (1985). 3.2. data analysis the data such as cutting height, number of tillers per plant, dry matter yield and nutritional parameters were subjected to analysis of variances (anova) using the generalized linear model (glm) procedure of statistical analysis system software (sas, 2002). the significant differences among the means of varieties were declared significant at p ≤ 0.05 and means were separated using least significant difference (lsd). the model employed was, yijk = μ + ri +vj+ lk + (vl)jk + eijk where, yijk = is the dependent variables; μ = overall mean; r = replication; vi = the effect of variety; lj = the effect of locations; vilj = the interaction effects of variety by location and eijk = random error. 3. results and discussion 3.1. dry matter yield, cutting height, number of tillers per plant and leaf to stem ratio the dry matter yield, cutting height, number of tillers per plant and leaf to stem ratio (ltsr) of desho grass varieties under irrigation in the lowland of dassench and hamer districts are presented in table1. the result of the current study revealed that areka-dzf#590 variety gave the higher (p<0.05) dry matter yield than kindokisha-dzf#591 and areka local check varieties but it was comparable to kulimisa-dzf#590 variety. however, the dry matter yield was insignificant (p>0.05) among the kulimisadzf#590, kindokisha-dzf#591 and areka local varieties. the cutting height above ground obtained from this study was not significantly (p>0.05) varied among the varieties but kindo kisha-dzf#590 gave taller cutting height above ground and whereas, areka local gave shortest cutting height above ground. moreover, areka-dzf#590 variety produced significantly (p < 0.05) higher branches per plant than kulimisa-dzf#590, kindokishadzf#591 and areka local but it was insignificant (p>0.05) among the kulimisa-dzf#590, kindokisha-dzf#591 and areka local varieties. on the other hand, kulimisa-dzf#590 had higher (p<0.05) ltsr than areka-dzf#590 and areka local varieties but it was comparable (p>0.05) to the kindo kisha-dzf#591 variety. conversely, arekadzf#590 desho grass variety gave significantly (p<0.05) higher number of tillers per plant than kulimisa-dzf#590, kindokisha-dzf#591 and areka local desho grass varieties but it was insignificant(p>0.05) among the latter of three grass varieties. the higher dry matter yield for arekadzf#590 variety from this study is due to the higher genetic potential of the variety to adapt to the tested environment than the other varieties. table 1. dry matter yield, cutting height, number of tillers per plant and leaf to stem ratio of desho grass variety grown in irrigated lowland of dassench and hamer districts in south omo in 2019 year. tested variety dry matter yield (t ha-1) cutting height (cm) number of tillers per plant ltsr kulumisa-dzf#591 25.42ab 123.83 51.83b 0.97a kindo kisha-dzf#592 22.86b 124.33 49.17b 0.90ab areka-dzf#590 35.09a 115 69.83a 0.72b areka local 16.79b 98.77 48.00b 0.68b sem 5.77 21.41 7.82 0.10 lsd 12.13 45.92 16.77 0.22 note: means with the same letter(s) are not significantly different at p>0.05. sem = standard error of mean and lsd = least significance difference. the previous studies reported by different scholars were demonstrated that the wider range of dry matter yield difference between desho grass varieties could be attributed due to differences in genetic potential of varieties (tekalegn yirgu et al., 2017; gadisa birmaduma et al., 2019; bimrew asmare et al, 2016; denbela hidosa et al., 2020). the result obtained on dry matter yield from this study for areka-dz#f590 variety is higher than previously reported values of 27.99, 28.35 and 28.74t ha-1 by denbela hidosa et al. (2020), tekalegn yirgu et al. (2017) and gadisa birmaduma et al. (2019), respectively. however, the dry matter yield obtained from this study for kulumsa-dzf#590 and kindokisha-dzf#591 was higher than reported value of (20.77 and 15 t ha-1) by denbela hidosa et al. denbela and demerew east african journal of sciences volume 15 (1) 71-78 74 (2020), respectively under rain fed condition but relatively similar to previously reported values of (26.52 and 23.37 t ha-1) by tekalegn yirgu et al. (2017) and 26.14 and 23.59t/ha by (gadisa birmaduma et al. (2019). furthermore, finding from our study for cutting height above ground was higher for arekadz#f590, kulimsa-dzf#591 and kindokishadzf#591 varieties to previously reported values which ranged from 71.27 96.30cm by gadisa birmaduma et al. (2019) and tekalegn yirgu et al. (2017), respectively. the difference in number of tillers produced per plant among the varieties of desho grass from our study could be attributed due to varietal differences. the variation in number of tillers per plant in different varieties of desho grass was also reported in ethiopia under different agroecologies due to varietal genetic makeup (denbela hidosa et al., 2020; tekalegn yirgu et al., 2017; bimrew asmare et al., 2016). the results on number of tillers per plant for all tested desho grass from our study is lower than previously reported value of 78 by demeke et al. (2017) and however, it was higher than reported value of 50 by asmare bimrew et al. (2017) for kulimisa-dzf#592 and areka-dzf#590 but lower kindokisha-dzf#591 and areka local desho grass varieties. the leaf fraction is associated with high nutritive value of the forage because leaf is generally of higher nutritive value (fekede feyissa et al., 2005). the result for leaf to stem fraction for tested desho grass varieties from our study was higher than reported values for kulumisa-dzf#592 and kindokisha-dzf#592 varieties (tekalegn yirgu et al., 2017) and (gadisa et al., 2019), but it was comparable to results reported by same authors for arekadzf#590 variety. generally, inconsistency in dry matter yield, cutting height, number of tillers per plant and leaf to stem ratio from our study as compared to previously reported studies by different scholars for tested desho varieties might be due to difference in soil parameters, harvesting age, irrigation effect, management and agro ecological differences where this was conducted. 3.2. effect of location on dry matter yield, cutting height, number of tillers per plant and leaf to steam ratio the effects of location on dry matter yield, cutting height above ground, number of tillers per plant and leaf to stem ratio are shown in table2. the results from this study demonstrated that the dry matter yield and cutting height above ground were not significantly (p>0.05) affected by tested locations. however, better dry matter and longer cutting height above ground obtained from dassench location than hamer location. conversely, significantly higher (p<0.05) number of tillers per plant and leaf to stem ratio were obtained from dassench location than hamer location. the higher dry matter yield, cutting height above ground, number of tillers per plant and leaf to stem ratio from dassench location than hamer is might be due to suitability of temperature and favorable soil parameters for plant which make faster plant growth and triggering more leaves per plats which are responsible for more dry matter yield, longer cutting height and number of tillers per plant. moreover, the highly significant environment effect and its high variance component could be attributed to the large differences between the two test location in altitude, physic-chemical properties of the soil, temperature, differences in both amount and distribution of annual rainfall, and other agro-climatic factors. in supports to the findings from our study the previous study reported by different scholars had confirmed that dry matter yield of forage species greatly influenced by weather conditions such as rainfall, temperature and precipitations (eshetie alemu et al., 2018; usman semman et al., 2018). moreover, the previously reported studies from ethiopia had demonstrated that the higher yield of forage could also be attributed to the favorable rainfall, temperature and available nutrient in the soil (denbela hidosa et al., 2020; asmare bimrew et al., 2017; gezahagn kebede et al., 2016; kebede gezahagn et al., 2016; yasin muhammad et al., 2003). table 2. the effects of location on dry matter yield, cutting height, number of tillers per plant and ltsr in irrigated lowland of dassench and hamer districts in south omo in 2019 cropping year. parameter measured tested locations dassench hamer mean sem lsd dmy( t ha-1) 27.42 22.66 25.04 4.39 9.42 cutting height (cm) 124.80 106.17 11.48 15.14 32.47 tillers per plant 61.00a 48.42b 54.70 5.53 11.86 ltsr 1.12a 0.52b 0.82 0.07 0.15 note: means with the same letter across row for dry matter yield, cutting height, tillers per plant and ltsr at 65 days are not significantly different at p>0.05. sem = standard error of mean and lsd = least significance difference. denbela and demerew dry matter yield and chemical composition of desho grass 75 3.3. effect of location by variety on dry matter yield, cutting height, number of tillers per plant and leaf to stem ration the effect of location by variety on dry matter yield, cutting height, number of tillers per plant and leaf to stem ratio are presented in table3. the result for effect of location and variety revealed higher (p>0.05) dry matter yield was observed in dassench location than hamer for all tested desho grass varieties. likewise, significantly taller (p<0.05) cutting height above ground was obtained from dassench location than hamer for kindokisha-dzf#592 when compared to areka-dzf#590 and areka local check but it was comparable (p>0.05) to kulumisadzf#591 variety. moreover, significantly (p>0.05) more number of tillers per plant were observed at dassench location than hamer location for all varieties except areka-dzf#590 variety which gave higher (p<0.05) number of tillers per plant but it was insignificant to other varieties for both locations. furthermore, the result on ltsr for location by variety interaction effect revealed the higher (p<0.05) ltsr obtained from the hamer location than dassench for kulumisa-dzf#591variety except areka-dzf#590 variety which is gave higher ltsr at dassench location but is similar (p > 0.05) to kindokisha-dzf#592 variety. the differences for tested parameters over location for tested varieties are might be due to variability in climatic and soil condition which indicated that the genetic make-up of tested desho grass varieties were influenced by environmental factors which shows to us different varieties have differential response to different planting locations. the previous study showed that variety by environment interaction is the result of changes in cultivar's relative performance across environments due to differential responses of the genotypes to various edaphic, climatic and biotic factors and this is help to identifying suitable genotype for specific location (yasin muhammad et al., 2003). table 3. effect of location by variety on dry matter yield, cutting height, number of tillers per plant and ltsr grown in irrigated lowland of dassench and hamer districts in south omo in 2019 cropping year. tested variety location parameter measured dmy (t ha-1) cutting height (cm) ntpp ltsr kulumsa-dzf#591 dassench 27.80ab 126.33ab 48.67b 0.56bc hamer 23.03ab 121.33ab 49.67b 1.39a kindokisha-dzf#592 dassench 22.93ab 168.00a 49.00b 0.85bc hamer 22.78ab 116.67ab 43.00b 1.30a areka-dzf#590 dassench 38.82a 101.00b 96.67a 0.93b hamer 31.35ab 113.33ab 47.00b 0.51d areka local dassench 20.1c 96.53b 49.67b 0.52d hamer 13.51c 80.67b 54.00b 0.50d sem 4.39 30.28 11.06 0.15 lsd 9.42 64.95 23.72 0.31 note: means with the same letter(s) across column for forage dry matter yield, cutting height, tillers per plant and ltsr at 65 days are not significantly different at p>0.05. sem = standard error of mean and lsd = least significance difference. 3.4. chemical composition of desho grass varieties the chemical compositions of tested desho grass varieties grown in irrigated lowland of dassench and hamer districts are presented in table4. the findings from this study for dm%, ash, cp, ndf and adf were not significantly (p>0.05) varied for all tested varieties. however, the areka-dzf590 variety had higher (p>0.05) cp content as compared to areka local variety used as local check. the variety used as local check had higher (p<0.05) ndf than arekadzf#590 and kulumisa-dzf#590 varieties but it was comparable (p>0.05) to the kindokishadzf#591 variety. on the other hand, arekadzf#590, kulumisa-dzf#590 and kindokishadzf#591 varieties had similar (p>0.05) ndf contents. the similarity in crude protein, ash and adf for all tested desho grass varieties is due to similarity in genetic make-up of varieties to accumulate similar nitrogen contents in a given environment. the result obtained from our study for cp value for all tested desho grass varieties were higher than previously reported values by different authors. accordingly, the cp values which ranges from 6.93-9.38% under different spacing and harvesting stages (asmare bimrew et al., 2017); the reported cp values was also ranges from 7.868.84% and 3.97-7.81% under different agro-ecologies respectively by bimrew asmare et al. (2018) and genet tilahun et al. (2017), respectively. generally, the previously reported studies by leng (1990) and smith(1993) indicated that crude protein content of about 60-70 g/kg, dm is required for maintenance of ruminant livestock and whereas, the cp content of 80-130g/kg, dm is required for moderate milk production (10-15kg/cow/day) for dairy cows reported by arc (1984) and humphreys (1991). therefore, the cp content obtained from our study for all tested desho grass varieties is above the maintenance requirement for ruminant livestock and denbela and demerew east african journal of sciences volume 15 (1) 71-78 76 enough to satisfy protein requirement for dairy cow to produce 10-15kg milk/ cow/day. the ndf and adf are frequently used as standard for forage quality testing. the ndf approximates the total cell wall constituents and is used to predict intake potential in livestock and whereas, adf primarily represents cellulose and lignin, and is often used to calculate digestibility of feeds (van soest, 1994). the value obtained from our study for ndf is lower than previously reported value which ranged 72.78-77.68% by asmare bimrew et al. (2017). but it was relatively comparable to values which ranged from 58.82-63% reported by bimrew asmare et al. (2018). moreover, the adf value obtained from out study was higher than the previous reported values which ranged from 45.0654.27% and 16.63-36.14% respectively by asmare bimrew et al. (2017) and genet tilahun et al. (2017). generally, the feeds containing ndf values of less than 45% could be classified as high quality, those with values ranging from 45% to 65% as medium and those with values higher than 65% as low quality (singh and oosting, 1992). based on this classification all tested desho grass varieties except areka local which used as check variety can be classified as medium quality forages class. table 4. the chemical compositions of desho grass variety grown in irrigated lowland of dassench and hamer districts in south omo in 2019 cropping year. tested variety dm (%) ash (g kg–1) cp (g kg–1) ndf (g kg–1) adf (g, kg–1) kulumisa-dzf#592 90 108.70 115.50 615.20b 448.40 areka-dzf#590 90 101.70 129.50 609.40b 479.80 kindo kisha-dzf#591 90 97.20 101.10 656.70ab 497.20 areka local 89 91.80 90.60 691.50a 505.20 sem 1.82 1.31 3.74 3.02 2.54 lsd 4.46 3.20 9.14 7.39 6.22 note: means with the same letter(s) across column for dm, ash, cp, ndf and adf at 50% flowering stage are not significantly different at p>0.05. dm = dry matter; cp = crude protein; ash = ash percentage; ndf = neutral detergent fiber; adf = acid detergent fiber; sem = standard error of mean and lsd = least significance difference. 4. conclusion the areka-dzf#590 variety gave higher (p < 0.05) dry matter yield and whereas, the areka local which used as check gave lowest dry matter yield. however, the kulimisa-dzf#591 and kindokisha-dzf#592 had higher (p<0.05) leaf to stem ratio and whereas, areka local desho grass variety used as check gave lower leaf to stem ratio. pertaining to testing location, higher (p<0.05) dry matter yield, cutting height, number of tillers per plant and leaf to stem ratio obtained from dassench location than hamer for all tested desho grass varieties. the dm%, ash, cp and ndf were not significantly (p > 0.05) varied for all tested varieties and however, areka-dzf590 variety had higher (p > 0.05) cp content as compared to areka local variety. based on results from this study we concluded that pastoralists and agro-pastoralists communities could be planted areka-dzf#590 desho grass variety followed by kulumisa-dzf#591 for higher dry matter yield and cp content. the future research should focus on the effect of planting space and cutting interval on forage dry matter yield and chemical compositions and feeding effect of superior candidates on livestock production. 5. acknowledgements this study was made possible with funding from regional agricultural growth program ii (agpii) to jinka agricultural research centre for the enhancing the pastoral livelihoods in south omo zone through improving livestock feed and feeding. therefore, we are extremely thankful the regional pastoral livelihood resilience project (rplrp) for providing fully fund support for research activity. also, we are grateful to acknowledge the jinka agricultural research center at jinka, in south omo zone for providing logistical support and debre zeit agricultural research center for provision of planting material (splits). finally, we are grateful to acknowledge the laboratory technician mr ashenafi kebede hailemariam from debre birhan agricultural research center for his wonderful cooperation in laboratory forage sample analysis. denbela and demerew dry matter yield and chemical composition of desho grass 77 6. references admasu teferi, abule ebro and tessema zewudu. 2010. livestock-rangeland management practices and community perceptions towards rangeland degradation in south omo zone of southern ethiopia. livestock research for rural development, 22(5):1–17. aoac (association of official analytical chemists). 1990. official methods of analysis, 15th ed. association of official analytical chemists. arlington, usa. arc (agricultural research council). 1984. the nutrient requirement of ruminant livestock. supplement no. 1 (common wealth agricultural bureau: faraham royal, uk. asmare bimrew, demeke solomon, tolemariam taye, tegegne firew and jane wamatu. 2016. determinants of the utilization of desho grass (pennisetum pedicellatum) by farmers in ethiopia. tropical grasslands-forrajes tropicales, 4(2): 112– 121. asmare bimrew, demeke solomon, tolemariam taye, tegegne firew, jane wamatu, et al. 2017. effects of altitude and harvesting dates on morphological characteristics, yield and nutritive value of desho grass (pennisetum pedicellatum trin.) in ethiopia. agriculture and natural resources journal, 50(1):1–20. berhanu tekleyohannes, girma abebe, jameroen, t., sayan, t. and somkiert, p. 2017. availability of feed resources for goats in pastoral and agropastoral districts of south omo zone, ethiopia.” international journal of research – granthaalayah, 5 (3): 154–160. bimrew asmare, yeshambel mekuriaw and lamrot tekliye. 2018. desho grass (pennisetum pedicellatum trin.) evaluation based on plant characteristics, yield and chemical composition under irrigation in northwestern ethiopia. journal of agriculture and environment for international development, 112(2): 241–251. bimrew asmare. 2016. evaluation of the agronomic, utilization, nutritive and feeding value of desho grass (pennisetum pedicellatum). phd dissertation, jimma university, ethiopia. pp. 90. csa (central statistical agency). 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1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15 (1) 61-70 licensed under a creative commons *corresponding author: jelaluk@gmail.com attribution-noncommercial 4.0 international license. antibiotic susceptibility of staphylococcus aureus isolated from chicken eggs, eastern ethiopia jelalu kemal1*, wakene beji2, and gebregeorgis tesfamariam2 1college of veterinary medicine, haramaya university, p.o. box, 138, dire dawa, ethiopia 2college of veterinary medicine, jigjiga university, ethiopia abstract introduction: staphylococcus aureus is responsible for a variety of infections in humans and animals that can pose a major public health burden in many countries, including ethiopia. objectives: this study was aimed to isolate staphylococcus aureus present on the shell surfaces and in the contents of chicken eggs, and determine antibiotic susceptibility patterns. material and methods: one hundred seventy-four (174) egg samples were obtained from open market and 161 from poultry farm. the surfaces of eggs were sampled using a sterile cotton swab. after sterilizing the shells, the egg contents were sampled. identification of staphylococcus aureus was done based on culture characteristics, and biochemical tests. the isolates were subjected to antibiotic susceptibility testing using disc diffusion method. results: a total of 93 (27.8%) staphylococcus aureus samples were isolated. from these, 28 (17.4%) were from haramaya university poultry farm while 65 (37.4%) were from market. in addition, 63 (18.8%) were from the shell while 30 (8.9%) were from the egg content. the occurrence of staphylococcus aureus in the egg shell from open markets was significantly higher than the content from the egg shells obtained from farms (p = 0.021). the level of staphylococcus aureus content was also significantly higher in the market (p = 0.003). all 76 staphylococcus aureus isolates were resistant to at least one of the antimicrobials tested with the overall value 3.9–92.0% level of resistance pattern showing higher resistant to penicillin (92%) and ampicillin (89.5%). a lower level of resistance was observed to chloramphenicol, gentamycin and ciprofloxacin with complete susceptibility to vancomycin. multiple drug resistance was detected in 86.8% of the staphylococcus aureus isolates. conclusion: the study showed a significant level of staphylococcus aureus with considerable antibiotic resistant pattern. further studies are needed to better define bacterial resistance to antibiotic agents with emphasis on surveillance of multiple drug resistance. keywords: antimicrobials; egg shell; egg content; open market; poultry farm; resistance to antimicrobials 1. introduction staphylococci are among the most common causative agents of food-borne outbreaks of infections worldwide and constitute a major public health burden and represent a significant cost in many countries (cdc, 2013; yang et al., 2016). reports demonstrate that staphylococcus aureus is responsible for a variety of infections in humans and animals (petrovski et al., 2006; hata et al., 2008). in humans, it is responsible for a variety of conditions ranging from superficial skin infections to life-threatening diseases, such as hemolytic pneumonia as well as endocarditis (lindsay and holden, 2004). the presence of the pathogen in food is one of the most common causes of staphylococcal food poisoning and toxic shock syndrome worldwide (becker et al., 2015). in animals, s. aureus causes mastitis, which is responsible for significant financial losses to dairy farmers (fitzgerald, 2012). some studies conducted in ethiopia found the occurrence of s. aureus from animal derivative food at various proportions such as 35.8% in adama (hailemariam mekonnen and tesfaye ali, 2010), 12% in jimma (haimanot tassew et al., 2010) and 24% in bishoftu (mekonnen addis et al., 2011). misuse of antimicrobials in animal foods can generate genomic selective pressures that enable microbes to adapt and acquire resistance (kohinur et al., 2010) that could globally become an increasing public health issue (michael et al., 2014). antimicrobial resistance, especially of pathogenic bacteria, has been partly attributed to the misuse of antimicrobial agents in medicine and agriculture (michael et al., 2014). antimicrobial agents have been used widely in both human and veterinary medical practices that are widely used by the poultry industry to enhance growth and feed efficiency (landers jelalu et al. east african journal of sciences volume 15 (1) 61-70 62 et al., 2012). incorporation of these agents into poultry feed poses the emergence of some resistant bacteria either through genetic or non-genetic mechanisms (ivanov, 2008). this and the husbandry practice such as feeding and watering used in the poultry industry made poultry a major reservoir of antimicrobial resistant pathogen (hedman et al., 2020). the reservoir of antibiotic resistant bacteria in poultry and poultry products including eggs implies a potential risk for transfer of antibiotic resistant bacteria, or resistant genes to humans (odwar et al., 2014). high level of resistance to antibiotics in s. aureus isolates has been documented by several authors from countries such as brazil (costa et al. 2000), united states (de oliveira et al., 2000), lebanese (zouhairi et al., 2010) and portugal (soares et al., 2011). it is a common belief in ethiopia that antimicrobials can be obtained without prescription (serawit deynu et al., 2017). to our knowledge, the extent of s. aureus contamination of eggs sold at retail outlets and farms, and the antimicrobial profile of the s. aureus isolates has not been adequately studied. there is no information from eastern ethiopia at all. therefore, this study was conducted to investigate the occurrence and antimicrobial resistance patterns of s. aureus isolated from chicken eggs collected from haramaya university poultry farm and nearby retail open market outlets. 2. materials and methods 2.1. description of the study site and study population the study was conducted at haramaya university poultry farm and local market at haramaya district. haramaya district is located in eastern hararge zone of oromia regional state. it is found at the distance of 508 km from addis ababa to the easterly direction at the elevation of about 2006 meters above sea level, 9∘26’n latitude and 42∘3’e longitude. the mean annual minimum temperature is 8.5∘c and with the maximum temperature of 24.4∘c. haramaya university poultry farm is located at 9∘26’n latitude, 42∘3’e longitude, and an altitude of 1980 meters above sea level and 513 km away from addis ababa. the annual average minimum and maximum temperature of the area are 8∘c and 24∘c, respectively (csa, 2012). haramaya university poultry farm practices intensive management system with exotic breed chickens. the farm aims to supply live chickens, eggs and three-month-old chicks to the surrounding farms, farmers, and private poultry farmers. the farm supplies antibiotics and other feed additives aimed to stimulate egg production, enhance growth performance, and for growing healthier chicks. some of these antibiotics and additives include egg stimulant (medion, bandung, indonesia), oxytetracycline 20% power (chengdu qiankun veterinary pharmaceutical co.,ltd., china), trisulpha forte (jordan vet and agr. med. ind., co., amman, jordan), amprolium 20% powder (chengdu qiankun veterinary pharmaceutical co., ltd., china), aminovit (medion, bandung, indonesia), laprovet (tours cedex 2, france) and vita chicks (medion, bandung, indonesia). 2.2. study design and sample size a cross-sectional study was conducted from december 2017 to april 2018 which was aimed at isolating s. aureus present on the shell surfaces and in the internal parts of chicken eggs, and determine antibiotic susceptibility patterns. a total of 335 chicken eggs from haramaya university poultry farm (n = 161) and local market (n = 174) in haramaya district were collected. 2.3. egg collection and transportation on average, ten eggs from haramaya university’s white leghorn caged birds and similarly 10 eggs from the retail market were collected once a week using a simple random sampling technique. each egg sample was collected separately using sterile plastic bags and transported in an ice box for analysis in the veterinary microbiology laboratory of haramaya university within a few hours of collection. 2.4. sample processing the sampled eggs contained in the sterile plastic bags were opened using scissors and processed. the entire surface areas of the egg shell were swabbed with sterile cotton swabs which were dipped into sterile buffered peptone water (bpw: oxoid ltd, hampshire, uk; lab m ltd., quest park, uk). a test tube that contained 10 ml bpw was used to incubate the egg shell swab samples separately. the egg contents were sampled from the same eggs from which the shell samples were collected after sterilizing the egg surfaces by immersing in 70% alcohol for at least 2 minutes; the eggs were then dried with air in a sterile chamber for 10 minutes, after which they were cracked with a sterile scalpel blade. stomacher bags containing 225 ml sterile bpw were used to homogenize the egg contents for around 1 minute in a stomacher and incubated at 37°c for 18–24 h (iso, 2002). the samples were then transferred onto blood agar plates containing 5% sheep blood (oxoid ltd, hampshire, uk; lab m ltd., quest park, uk) and then incubated under aerobic conditions at 37°c for 24-48 h, depending on the rate of growth of the bacteria. an initial bacteriological characterization was performed by evaluating the morphology of the colonies and the presence and type of haemolysis. s. aureus identification was done based on gram staining, morphology, and conventional biochemical tests, including catalase, coagulase, and mannitol fermentation tests as described by quinn et al. (2002). 2.5. antibiotic susceptibility test the s. aureus isolates were tested for antimicrobial susceptibility by the kirby-bauer disc agar diffusion method on mueller-hinton agar medium (oxoid ltd, jelalu et al. antibiotic susceptibility of staphylococcus aureus isolates 63 hampshire, uk; lab m ltd., quest park, uk), according to the guidelines of the clinical and laboratory standards institute (clsi) (clsi, 2013). the antimicrobial discs (oxoid ltd., cambridge, uk) were selected in line with the recommendation of clsi 2013; ampicillin (10µg/disc), amoxicillin (20µg/disc), chloramphenicol (30µg/disc), penicillin g (10iu/disc), tetracycline (30µg/disc), gentamicin (10µg/disc), cefoxitin (30µg/disc), erythromycin (15µg/disc), streptomycin (10µg/disc), kanamycin (30µg/disc), ciprofloxacin (5µg/disc), and trimethoprimsulfamethoxazole (sxt, 25µg), vancomycin (30µg/disc). the antimicrobials used were selected from the currently available and commonly used chemotherapeutic agents for the treatment of s. aureus infection in humans and animals. the results were read and interpreted based on the diameter of the zone of inhibition. the strains were designated as resistant (r), intermediate resistant (i), or susceptible (s) to a particular antibiotic based on the cutoff value (table 1). multiple drug resistant (mdr) were recorded for isolates showing resistance to more than two antimicrobials (rota, 1996). 2.6. quality control all the media and reagents were subjected to quality control using standard bacteria. staphylococcus aureus atcc 29213 and s. aureus atcc 25923 were used as quality control during the test. table 1. zone diameter interpretive standards chart for staphylococci species (clsi, 2013). antibiotic agent disc code potency (𝜇g) zone diameter nearest whole mm r i s amoxicillin aml 25µg ≤19 ≥20 ampicillin amp 10 ≤13 14–16 ≥17 chloramphenicol c 30µg ≤12 13-17 ≥18 penicillin g p 10iu ≤28 ≥29 tetracycline te 30µg ≤14 15-18 ≥19 gentamicin cn 10µg ≤12 13-14 ≥15 cefoxitin fox 30µg ≤21 ≥22 erythromycin e 15µg ≤13 14-22 ≥23 streptomycin s 10µg ≤11 12-14 ≥15 kanamycin k 30µg ≤13 14-17 ≥18 ciprofloxacin cip 5µg ≤15 16-20 ≥21 sulphamethoxazole trimethoprim sxt 25µg ≤10 11-15 ≥16 vancomycin va 30µg ≤15 ≥15 note: r = resistance, i = intermediate, and s = susceptible. 2.7. data management and analysis the data were entered into excel databases and analyzes using stata version 11.0 statistical software package programs. descriptive statistics such as percentages and frequency distribution were used to describe the nature and the characteristics of the data. comparisons between sample source and sample type were done by chi-square (χ2). logistic regression was used to reveal the strength of the association of the potential risk factors with positivity of the samples. in this line, the degree of association between risk factors and the prevalence of s. aureus was analyzed using test odds ratio (or). in all the analysis, the level of significance was set at 5% and the 95% confidence interval. 3. results 3.1. occurrence of s. aureus spp. in raw chicken egg shell and egg contents from the total 335 chicken eggs sample examined for bacteriological status, 93 (27.8%) of the samples harbored s. aureus. the occurrences of s. aureus varied among the sampling types and sources. out of the 93 (27.8%) eggs that tested positive for s. aureus, 63 (18.8%) were from the shell while 30 (8.9%) were from the internal content of the eggs. of the 93 positive samples, 28 (17.4%) were the ones sampled from the poultry farm while 65 (37.4%) were from the open market (retail outlets). the occurrence of s. aureus in the egg shell collected from the local market was significantly higher than the level of s. aureus in the egg shells obtained from the poultry farm (ci = 0.2904 0.9078; p = 0.021). the level of s. aureus in the egg contents from the open market was also significantly higher than the level of s. aureus in the egg contents from the poultry farm (ci = 0.09620.6085; p = 0.003). similarly, the overall proportion of s. aureus from the eggs sampled in the open market was significantly higher than the level of s. aureus from the eggs obtained from the poultry farm (ci = 0.25910.7585; p = 0.003) (table 2). jelalu et al. east african journal of sciences volume 15 (1) 61-70 64 table 2. occurrence of s. aureus in egg shell and content of raw chicken eggs from local markets and poultry farm in eastern ethiopia. sample source poultry farm open market total or(95% ci) pvalue no. examined no. +ve (%) no. examined no. +ve (%) examined positive (%) egg shell 161 22 (13.7) 174 41 (23.6) 335 63 (18.8) 0.5 (0.2904 0.9078) 0.021 egg content 161 6 (3.7) 174 24 (14.9) 335 30 (8.9) 0.25 (0.0962 0.6085) 0.003 total 161 28 (17.4) 174 65 (37.4) 335 93 (27.8) 0.5 (0.2591 0.7585) 0.003 note: or = odds ratio. 3.2. antibiotic susceptibility testing in the antimicrobial resistance trials, out of 93 s. aureus isolates, 76 (81.7%) were subjected to antimicrobial resistance test. all the isolates showed resistance to at least one of the antimicrobials tested. the percentage of isolates susceptible, intermediate, and resistant to each antimicrobial agent is outlined in table 2. overall, s. aureus isolates revealed 3.9–92.0% level of resistance pattern to the antimicrobials tested. a large proportion of the isolates were resistant to penicillin (92%), ampicillin (89.5%), amoxicillin (55.3%) and erythromycin (51.3%). a lower level of resistance was observed against chloramphenicol, gentamycin and ciprofloxacin with a resistance level of about 3.9% each. all the s. aureus isolates were susceptible to vancomycin (100%) (table 3). the level of multiple resistance patterns in s. aureus isolates is given in table 4. multiple drug resistance to more than two antimicrobial agents was detected in 66 (86.8%) of the total 76 s. aureus isolates. three isolates (4.5%) were resistant to ten antimicrobials tested. fourteen isolates were resistant to 4 antimicrobials tested. multiple drug resistance was defined as resistance exhibited to more than two antimicrobials tested. among the s. aureus isolates, 19.7%, 21.2%, and 18.2% exhibited resistance to three, four, and five antimicrobials, respectively. table 3. antimicrobial resistance patterns of s. aureus isolates (n = 76) from chicken eggs sampled from a poultry farm and open local markets in haramaya district, eastern ethiopia. antimicrobial agent disc potency (𝜇g/disc) resistant n (%) intermediate 𝑁 (%) susceptible 𝑁 (%) ampicillin 10 68 (89.5) 0 (0.0) 8 (10.8) amoxicillin 20 42 (55.3) 5 (6.6) 29 (38.1) cefoxitin 30 8 (10.5) 0 (0.0) 68 (89.5) chloramphenicol 30 3 (3.9) 2 (2.6) 71 (93.4) ciprofloxacin 5 3 (3.9) 2 (2.6) 71 (93.4) erythromycin 15 39 (51.3) 0 (0.0) 37 (48.7) gentamycin 10 3 (3.9) 2 (2.6) 71 (93.4) kanamycin 30 16 (21) 3 (3.9) 57 (75) penicillin 10 iu/disc 70 (92) 2 (2.6) 4 (5.3) streptomycin 10 27 (35.5) 4 (5.3) 45 (59.2) tetracycline 30 26 (34.2) 3 (3.9) 46 (60.5) trimethoprim sulfamethoxazole 25 7 (9.2) 0 (0.0) 69 (90.8) vancomycin 30 0 (0.0) 0 (0.0) 76 (100%) jelalu et al. antibiotic susceptibility of staphylococcus aureus isolates 65 table 4. resistance profiles of s. aureus isolates (n = 76) against 13 antimicrobial agents from chicken eggs sampled from a poultry farm and open local markets in haramaya district, eastern ethiopia. drugs developed resistance antimicrobial resistance pattern multiple drug resistance of s. aureus isolates with same pattern percentage 3 aml, amp, p 13 19.7 4 aml, amp, p, e 14 21.2 5 aml, amp, p, e, fox 12 18.2 6 aml, amp, p, te, s, c 7 10.6 7 aml, amp, p, e, te, k, sxt 6 9.9 8 amp, aml, p, e, te, k, fox, s 6 9.9 9 aml, amp, p, e, s, c, sxt, fox, k 5 7.6 10 aml, amp,p, e, cn, sxt, k, cip, fox 3 4.5 total 66 100% 4. discussion the presence of pathogenic bacteria in food, including table chicken eggs, may pose a serious health problem (baumann and sadkowska, 2011; pyzik and marek. 2012). eggs are food with high nutritive values for humans. similarly, they are an excellent source of nourishment for many pathogens. bacteria can infect eggs through diverse means such as during development in the reproductive system, directly after hatching, during storage and transport, or even while preparing the eggs as food for consumption (stępień et al., 2009). among the most widespread foodborne infections directly connected with egg consumption are s. aureus infections. our study revealed high level of s. aureus contamination of table chicken eggs accounting for 27.8% of isolates. comparable with the results of this study, stępień et al. (2009) found 19.8% s. aureus from table eggs. the available literature shows that while these bacteria are isolated from eggs with varying frequency depending on geographical location, they can pose a serious threat to consumer health by inducing food poisoning. in france, for instance, a fairly high percentage (11%) of cases of food poisoning in 1999–2000 resulted from eating eggs and egg products contaminated with staphylococci (haeghebaert et al. 2002). in 2009, analysis of the epidemiological situation of food poisoning and foodborne infections in poland showed that 25% of food poisoning cases were induced by s. aureus. this was caused by consumption of table eggs (baumann and sadkowska, 2011). in our study, although most of the s. aureus were isolated from shells, a considerable number of the pathogen was isolated from the contents. corroborating the results of this study, pyzik and marek (2012) reported a fairly higher rate of s. aureus isolates on the shells of the eggs (55.5%) than the contents (27.8%) from poland. in contrast to our results, however, stępień et al. (2009) reported less isolates of s. aureus from egg shells (10.4%) than from egg contents (35.2%) that were collected from largeand small-scale poultry farms and eggs purchased from supermarkets. these variations might be due to different sampling techniques, areas, time, storage practice and the low isolation rate of culture methods compared to more sensitive immunological and molecular methods. in this study, significantly higher numbers of s. aureus isolates were detected in the egg samples collected from the open markets than from eggs sampled from haramaya university poultry farm. this variation might be attributed to differences in the level of care given and sanitation practiced at the two egg sample collection sources. this may imply that a higher care is given to eggs and better sanitation is practiced at the poultry farm of the university than at poultry farmers from which the farmers sell eggs in the open market. eggs collected from hens kept in a cage system have been less likely exposed to the pathogens than those kept in litter system and retail outlets or open markets. there are several critical points that contribute to the contamination of eggs with microorganisms in the pathways of reaching the consumers such as the environment, storage condition, transport and handling practices (stępień et al., 2009). another important point that has a serious threat to consumer health with a global concern is antimicrobial resistance of s. aureus isolated from eggs. in this study, all the isolates showed resistance to at least one of the antimicrobials tested. the proportion of amoxicillin resistant isolates found in this study is supported by the report of serawit deynu et al. (2017) who reported 90.9%. fikre gizaw (2014) reported a comparable proportion of penicillin resistant s. aureus to the present study who detected 90.2%. this higher rate of resistance to penicillin could be due to their frequent use in ethiopia (gebretekle gebremedhin and mirgissa kaba, 2016). all (100%) of the s. aureus isolates showed susceptibility to vancomycin. this higher susceptibility rate to vancomycin in the present study is comparable to the global estimate (zhang et al., 2015). serawit deyno et al. (2017) reported that 74.2% of s. aureus isolates jelalu et al. east african journal of sciences volume 15 (1) 61-70 66 showed resistance against vancomycin in ethiopia. meseret guta et al. (2014) reported high vancomycin resistant s. aureus which is inconsistent with our study. can et al. (2017) reported a similar finding that all isolates of s. aureus were susceptible to vancomycin followed by chloramphenicol (97.5%), penicillin (95%) and ampicillin (92.5%). similarly, yang et al. (2016) displayed a 100% susceptibility to vancomycin and cefoxitin with a higher rate to chloramphenicol. vancomycin has been considered the best drug for the treatment of staphylococci related infections. it has been known as the last line of defense against gram-positive cocci infections (micek, 2007). susceptibility of the isolates to vancomycin and gentamicin that we found in this study is in agreement with the findings of other researchers from different countries (gündoğan et al., 2006; normanno et al., 2007; pesavento et al., 2007; hanson et al., 2011; can and çelik, 2012; hu et al., 2013). consistent with the results of this study, pyzik et al. (2014) reported that all s. aureus isolates tested were susceptible to chloramphenicol and gentamicin. among the isolates of s. aureus, the most frequently observed resistance patterns were observed against amoxicillin, ampicillin, penicillin g, erythromycin and tetracycline. the higher resistance frequency against beta-lactams, penicillin, ampicillin and amoxicillin, among the isolates from chicken eggs could be attributed to the extensive and uncontrolled use of these groups of antibiotics in the agriculture sector. in agreement with the present finding, rasoul et al. (2015) reported a susceptibility rate of s. aureus isolates to be 94.9% and 83.7% for cefoxitin and trimethoprim sulfamethoxazole, respectively. however, our finding is distantly related to the finding of rasoul et al. (2015) who reported that 69.4% of s. aureus isolates were susceptible to tetracycline. in some other studies s. aureus showed varied resistance level against erythromycin (1.7%– 100%), tetracycline (5%–84%), ciprofloxacin (0%–42%) and vancomycin (9%–46%) (attien et al., 2013; adegoke and okoh et al., 2014; gharsa et al., 2015; schaumburg et al., 2015). high penicillin resistance of s. aureus isolates was also identified in other parts of the world (gharsa et al., 2015; chairat et al., 2015). multidrug resistance was detected in 66 (86.8%) of the total 76 s. aureus isolates. the most frequently observed resistance pattern was resistance to ampicillin in combination with penicillin, erythromycin and amoxicillin. similar findings were reported by fikru gizaw (2014) with multiple drug resistance of 89.3% of the total isolates tested. barena and fetene (2003) and chao et al. (2007) reported a similar rate of multi-drug resistant s. aureus (80%) and (79%) with the present investigation respectively. the resistance against antimicrobial observed in this study is slightly higher than reported by sharma et al. (2011) who indicate that 60–70% of the s. aureus isolates showed multiple drug resistance. such a high incidence of multi-drug resistance may apparently have occurred due to indiscriminate use of antimicrobial agents which enhance the development of drug resistance (van den bogaard and stobberingh, 1999). the multiple drug resistance observed in the current study might also be mediated by genetic mobile elements such as plasmids, transposons, and integrons as seen in other studies (macrina and archer, 1993; firth and skurray, 2006; shearer et al., 2011; li and zhao, 2018; partridge et al., 2018). 5. conclusion the results of this study have revealed that a considerably high percentage of the chicken eggs were contaminated with s. aureus. egg shells harbored a significantly considerable level of s. aureus compared to egg contents. a significantly higher rate of contamination was recorded for eggs sampled from the open market than those sampled from haramaya university poultry farm. detection of the high prevalence of s. aureus in this study indicates a potential risk of food poisoning. the results have also demonstrated the existence of an alarming level of resistance of s. aureus to antimicrobial agents commonly used in veterinary and human practices such as ampicillin, amoxicillin, penicillin and erythromycin. the majority of s. aureus isolates showed multiple resistances to drugs, ranging from three to nine of the antimicrobials tested. the high prevalence of s. aureus and isolates with multiple drug resistance is alarming because this could pose a significant risk to public health if the microorganisms are transmitted to humans through food chains. therefore, additional research is required with continuous surveillance and monitoring of pathogens to better define this bacterial resistance to antimicrobial agents with emphasis on surveillance of multiple drug resistant s. aureus isolates. 6. acknowledgements we acknowledge haramaya university for providing material supports for the research. we also thank mr. dereje regassa, haramaya university college of veterinary medicine, for his support during the laboratory tests. 7. references adegoke, a.a. and okoh, a.i. 2014. species diversity and antibiotic resistance properties of staphylococcus of farm animal origin in nkonkobe municipality, south africa. folia microbiologica (praha), 59: 133–140. attien, p.s., moussaoui, w., dadié, t., chabi, s.k., djéni, t., bankole, h.s., kotchoni, s.o., edoh, v., prévost, g., djè, m. et al., 2013. prevalence and antibiotic resistance of staphylococcus strains isolated from meat products sold in jelalu et al. antibiotic susceptibility of staphylococcus aureus isolates 67 abidjan streets (ivory coast). african journal of microbiology research, 7: 3285–3293. barena, b. and fetene, d. 2003. nasal carriage of methicillin resistant staphylococcus aureus strains among inpatients of jimma hospital, south western ethiopia. ethiopian journal of health science, 13: 30–40. baumann, p.a. and sadkowska, m. 2011. foodborne infections and intoxications in poland in 2009. przegla ̧d epidemiologiczny, 65: 227–234. becker, k., skov, r.l. and von eiff, c. 2015. staphylococcus, micrococcus, and other catalasepositive cocci. pp. 354–382. in: jorgensen, j.h., carroll, k.c. funke, g., pfaller, m.a. landry, m.l. richter, s.s. and warnock, d.w. 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hassenmohammed2008@gmail.com attribution-noncommercial 4.0 international license. estimating surface water inflow into lake lego, a closed basin in northeastern ethiopia hassen mohammed department of natural resource management, wollo university, p.o. box 1145, dessie, ethiopia abstract background: a surface water hydrologic characteristic of closed drainage basin of lake lego is not yet well-known amid constant reductions in depth and area over the last 72 years. objective: predicting the amount of surface water inflow into the terminal lake lego and evaluating its impacts on lake morphometric parameters. materials and methods: weather (daily precipitation, minimum and maximum temperature), geospatial image (digital elevation model and land use and cover), physical and chemical soil characteristics and existing land management data were used. soil and water assessment tool and arcgis computer models were used for the analyses. results: the basin generated 304.3 mm of average annual surface runoff while the contribution of the baseflow was only 91.8 mm of water. in aggregate, the basin contributed an average surface water inflow of 21,984,159 m3 y–1 during the simulation period. the trend in precipitation was insignificant for the duration of analysis while the lake water volume has been reducing at the rate of 2,817,680 m3 y–1 for the same period. the declining lake water was affecting lake morphometric parameters. the depth, surface area, and volume of the lake were shrinking at the rate of 0.128 m y–1, 3.8 ha y–1 and 0.29% y–1, respectively. the water residence time of the lake was estimated as 45 years. conclusion: the results of the study revealed the contribution of surface water inflow into the lake and its impacts on depth, area and volume of the lake. the findings provide valuable information for policy development and decision making for implementation of integrated water resource management in the watershed and enhance streamflow into the lake. keywords: ankerkah river; baseflow; ethiopia; lake lego; swat 1. introduction mountain lake lego (‘lego’ is also locally named and spelled as ‘hayq’, haik or ‘hayk’, as stated in some literature), lying in a closed hydrological basin, is a highland freshwater body that provides a visually scenic look to northeastern part of south wollo region. lake lego, which is an extremely productive nile tilapia (o. niloticus) fishing environment, has become a source of livelihoods for thousands of people from the lake community and nearby towns. basic morphometric parameters of lake lego had not been known until 1940. morandini in 1941 (baxter and golobitch, 1970) explored the maximum depth and surface area of the lake for the first time as 88.2 m and 2,302 ha, respectively. late bathymetric and land use and land cover studies carried out by hassen mohammed et al. (2013, 2015) indicated that the lake experienced reductions in depth and surface area by 6.8 m and 56.3 ha, respectively over the last 72 years. lake floor pollen and charcoal analyses (darbyshire et al., 2003) provided evidence that the vegetation of the lake drainage basin shrunk due to human influence during the last 3000 years. lamb et al. (2007) investigated the oxygen and carbon isotope compositions of sedimentary carbonates, which formed in lake lego for a 2000-year period. the result demonstrated the isotopes were mainly influenced by evaporative enrichment rather than surface and groundwater inflows due to reduced rainfall (lamb et al., 2007; ghinassi et al., 2012). stratigraphical, geomorphological, and geochronological dating analyses reconstructed the late holocene lake-level fluctuations and paleohydrological history of lake lego. the result mailto:hassenmohammed2008@gmail.com hassen east african journal of sciences volume 16(2): 101-114 102 highlighted the presence of shoreline fluctuations during the last 3500 years and three main droughts occurred during the little ice age (ghinassi et al., 2012). studies conducted in the past 80 years are largely morphometric conducted on lake dimensions. streamflow studies on the lake have mostly lagged behind. research findings show ecohydrologic condition of lake basins related to their streams or rivers falls within the realm of limnology, is now understood (schäfer et al., 2016). although the traditional perception of freshwater degradation has been usually linked to pollution, increasing human activities in a watershed have more profound effects on environmental quality. most river basins in the world have been dramatically modified due to unsustainable development of agriculture, grazing, deforestation, and urbanization (united nations environmental protection (unep), 2004). lake lego has been increasingly declining in depth, area and volume (molla demlie et al., 2007; hassen mohammed et al., 2013). there has not been water abstraction for municipal consumption, industrial use, irrigation, or power generation from the lake. in reality, for a lake watershed where 26% of its geographical area is occupied by water (watershed to surface area ratio = 2.9), the source of water to the lake is dominated by precipitation falling on the lake. however, inflows through a river, streams and overland are the second sources of lake water. ankerkah river, which drains 50.1% of the landscape of the lake basin, was used to permanently feed the lake until sometime in the 1960s (hassen mohammed et al., 2013) by receiving overflow from upstream lake hardibo. the river is now intermittent where the channel is empty in the driest months of may and june. no gaging station at the river and no lake level recorder is installed to monitor streamflow and observe lake level variations. in the face of continuous lake surface area decline, the quantity of inflow of water from its closed watershed into the downstream lake was not yet systematically predicted with mathematical models, either. methods used to estimate surface water inflow for sites where no streamflow data are monitored include drainage-area ratio method, regional statistics, regression and watershed hydrologic modeling (emerson and dressler, 2002; douglas et al., 2005). examination of the magnitude and quantitative changes in surface water inflow entering into the lake provides information about the persistent modification of lake morphometric parameters, which is necessary for planning use of the water resources as well as sustainable use of lake water. according to the concept of ecohydrology and its scientific foundations towards lake basin management (zalewski and robarts, 2003), the possibility of augmenting ecosystems resilience to anthropogenic changes can be achieved through the manipulation of biota and hydrologic interactions in a lake landscape. in this study, a connection among the lake and its watershed was established by examining the intimate link between what happens in the lake with what is happening in its watershed as a manifestation of ecohydrologic principle. the objectives of this study were, therefore, to predict the amount of surface water inflow occurring on the basin and evaluate what has been going on the lake morphometric parameters due to streamflow position. 2. materials and methods 2.1. general description of the study area lake lego watershed forms the uppermost part of the awash river basin with a hydrological area of 8623 ha. geographically, it is bounded between 39.6816°– 39.8108° e longitudes and 11.2374°–11.3855° n latitudes in the northeast escarpment of south wollo zone, northeastern ethiopia at the western margin of the afar triangle (figure 1). the lake is centripetal with an area of 2246 ha and a maximum depth of 81.4 m (hassen mohammed et al., 2013, 2015). physiographically, the basin is situated in woyna dega (mid-land) and dega (highland) agro-ecological zones (aezs) (1500–2300 and 2300–3200 meters above sea level, respectively), where the lake and adjacent low-lying plains in the basin are surrounded by an elongated block of graben mountains, which descends downwards to provide a space for the lake. the dega section, in the upstream 11.8% of the basin, is dominated by very steep mountains with a pronounced stream dissection and high local relief. the fluvial ankerkah river that starts in the upper farmlands underlies this section. ankerkah river is the primary tributary of lego lake, although the lake also receives nominal flows overland and through a series of thirty tributaries all-round the lake. the lake used to drain to the millie river, which flows east into awash river before it descends in depth and is converted into a closed drainage basin with no outlet (molla demlie et al., 2007). relatively plain land, with some hill slopes in the middle, is the 88.2% woyna dega section in the downstream of the basin. this land occupies the water body and is less dissected landscape than the dega section with low local relief. the moisture regime of the site comprises four-rainfall hassen estimating surface water inflow into lake lego 103 patterns: the small rainy season, very dry spell, big rainy season, and dry season. the mean annual precipitation is 1135.8 mm and the mean annual minimum and maximum temperatures are 10.5 and 25.9 oc, respectively averaged over 56 years (1962 to 2017) data record at hayq town station. the farming system of the study area comprises rainfed agriculture and small livestock holdings. figure 1. location map of the study watershed. 2.2. data, methods and analyses gathering a combination of input information that actually has been occurring in the basin was done to accurately predict the movement of water. shuttle radar topographic mission (srtm) digital elevation model (dem) with a resolution of 30 m was obtained from open access site (http://dds.cr.usgs.gov/srtm/). national meteorological service agency (nmsa) supplied the climatic elements (daily precipitation, maximum and minimum air temperature), covering a span of 10 years (2008 to 2017), from hayq and kombolcha class 2 and 1, respectively climate stations. the data from kombolcha station were used to build weather generator database file using wgnmaker macro and pcpstat computer algorisms to fill in missing rainfall and temperature data of hayq town station. hargreaves method (hargreaves et al., 1985) was used to calculate the potential and actual evapotranspiration. historical records of precipitation data, in parallel with this study simulation period, was used for annual rainfall trend analysis. trend analysis of rainfall time series were evaluated with graphical method. land cover data were obtained by visually interpreting google earth image captured in 2017 on-screen. the spatial land cover interpretation was improved with global positioning system (gps) receiver assisted groundwork by collecting ground control points. generally, seven land use/land cover classes were identified (figure 2) based on land cover classification system (lccs) (food and agriculture organization (fao), 2000). the seventh land use/cover class, orchard, is pieces of enclosed land planted with fruit trees where 99% of it covers stimulant perennial crop called khat (catha edulis). it is sorted and portrayed here on the map to show its aggressive expansion from 0.27% in 2007 to 4.0% in this study at a cost of annual cropland. http://dds.cr.usgs.gov/srtm/ hassen east african journal of sciences volume 16(2): 101-114 104 figure 2. land use/land cover distribution of lake lego basin captured in 2017. physical and chemical soil characteristics were collected from: (1) secondary data review (eastern amhara soil study corridor conducted in 2015) and (2) in situ description of soil surface characteristics and other primary soil parameters according to the guidelines of fao (2006). information from the two sources was used to identify five primary soil-mapping units. the third source of soil data was laboratory analyses of soil samples. six soil profile pits were dug on soil types of representative sites (figure 3), apparent horizons were identified on which undisturbed, and disturbed soil samples were taken on each layer for laboratory analyses. texture (pipette method), organic carbon (walkley and black method), hydrologic soil group based on natural resource conservation service (nrcs) (2007), bulk density (core ring method), field capacity (sand box method), hydraulic conductivity (constant head method) and organic matter, permanent wilting point, available water capacity, porosity, soil albido, soil erodibility (k) and soil crack volume (pedo transfer function) were determined according to the standards set by different researchers (williams, 1995; sahlemedihn sertse and taye bekele, 2000; saxton and rawls, 2006; nrcs, 2007). hassen estimating surface water inflow into lake lego 105 figure 3. soil types and profile locations of lake lego basin. land management operations, such as bunds constructed within lake basin were located spatially. other management operations, like vegetative filter strip along streamlines and around the lake, strip cropping, residue management, contouring, etc., were recorded in the field. support practice factor (pusle) were estimated for all land use/covers based on land management status and slope ranges according to wischmeier and smith (1978), haan et al. (1994), hurni (1986), and neitsch et al. (2011). main channels’ geometry (width and depth) and characteristics (bed and bank material and cover condition) were exhaustively measured in the field. all outlets of defined streams and ankerkah river were captured and manually added during modeling process to quantify streamflow movement through the channel network of the lake basin, via their exits that enter into the lake. in addition, landscapes with no defined channels bordering the lake, which directly supply overland flow to the lake, were clipped from the surface runoff map to estimate the net runoff entering the lake from these polygons. streamflow (inflow) and other water balance components of the lake watershed were predicted with soil and water assessment tool (swat) model for monthly time-step using comprehensive data input mentioned above. swat model was chosen for various reasons: first, swat has been already successfully applied for streamflow for a wide range of scales and environmental conditions around the globe (gassman et al., 2007). second, swat has been effectively calibrated and validated in various hydrometric watersheds of ethiopia for streamflow (shimelis gebriye et al., 2010a, 2010b; degefie tibebe and woldeamlak bewket, 2011; lemann et al., 2016). third, swat can model watersheds with no monitoring data (e.g. stream gaging data) (neitsch et al., 2011). fourth, swat model was calibrated, validated and underwent uncertainty analyses at maybar gaging station for streamflow by hassen mohammed et al. (2016). soil conservation research project (scrp) watersheds have the longest and most accurate record of rainfall, runoff, soil loss, and sediment yield and streamflow data available in ethiopia. maybar is one of the sites located in the upper awash river basin (scrp, 2000). maybar instrumental watershed and lake lego basin are neighborhood, located within the same upstream awash river basin (figure 1). both watersheds are dominated by agriculture, with soil and water conservation structures built to control soil erosion to assist the rainfed subsistence farming. in swat, surface runoff was simulated using a modified curve number method (soil conservation service (scs), 1972) at hydrologic response unit (hru) level. the mean annual watershed value of water balance hassen east african journal of sciences volume 16(2): 101-114 106 components averaged over the whole simulation period (2012 to 2017) was calculated with the following equation (neitsch et al., 2011): 𝑆𝑊𝑓 = 𝑆𝑊𝑖 + ∑ (𝑅𝑑𝑎𝑦 − 𝑄𝑠𝑢𝑟𝑓 − 𝐸𝑇𝑎 − 𝑊𝑠𝑒𝑒𝑝 − 𝑄𝑔𝑤) 𝑡 𝑖=1 (1) where, 𝑆𝑊𝑓is final soil water content (mm); 𝑆𝑊𝑖is initial soil water content on the day i (mm); t is time (days); 𝑅𝑑𝑎𝑦is amount of precipitation on day i (mm); 𝑄𝑠𝑢𝑟𝑓is amount of surface runoff on day i (mm); 𝐸𝑇𝑎is amount of actual evaporation on day i (mm); 𝑊𝑠𝑒𝑒𝑝 is the amount of percolation and bypass flow exiting the soil profile bottom on a day i (mm); and 𝑄𝑔𝑤 is the amount of return flow on a day i (mm). streamflow was routed through the drainage channel system using a variable storage method (williams, 1969). the lake morphometric parameters were estimated using a combination of methods. the present lake surface area was updated using detailed interpretation of goggle earth image as mentioned in section 2.2. the lake area was used to estimate present lake depth using regression equation (eq. 2) and this depth was used to estimate present volume using established bathymetric data (3d grid file) by hassen mohammed et al. (2013) for lake lego. 𝐴 = −0.09𝑑2 + 362.5𝑑 − 3608.2 (2) where, a is an area of lake surface in ha and d is depth in m. for an enhanced modeling outcome, the watershed was partitioned into a number of subwatersheds and hrus. a total of 375 subwatersheds and 3963 hrus were created by discretizing the basin at 15 ha very fine critical source area to benefit the simulation, because different areas of the watershed were dominated by land uses, soils and slopes dissimilar enough in variety to impact hydrology. precipitation is the most dominant factor among climate variables in affecting surface water inflow in the lake basin. annual trend analysis of rainfalls observed at hayq town station, which covered from 1962 to 2017 years, where this study period falls into, were carried out with graphical method (sen, 2012). 3. results and discussion 3.1. the hydrologic variables of lake lego basin the results of hydrologic variables aggregated at the lake basin level are shown in table 1. these constituents are mean annual water balance components of the watershed averaged over the whole simulation period (2012 to 2017). the data gives an image of how basin annual rainfall was converted into different hydrologic components while moving through the continuum of the soil, vegetation and atmosphere. table 1. mean annual values of water balance components of lake lego basin. variable f sw i sw yearr surfq et seep w gw q fsw isw amount (mm) 36.4 33.8 1135.8 313.5 574.4 37.7 207.6 2.7 rainfall (%) − − − 27.6 50.6 3.3 18.3 0.2 almost half of the total rainfall (𝑅𝑦𝑒𝑎𝑟) (50.6%) released through evapotranspiration (et) is a significant water loss from the drainage basin, which characterizes 88.2% woyna dega and 11.8% dega aezs with a mean elevation of 2,199 m a.s.l. and relatively warm climate (mean annual temperature = 18.2 ℃). the bimodal rainfall regime of the area enables the growing of annual crops twice a year that increases transpiration and surface runoff. the rainfallrunoff link of the basin accounted for 27.6%, which is relatively low because 25.6% of the basin is water body, which does not generate runoff and 43% of the area is under slope class of 0–8%. the runoff coefficient is analogous to similar study carried out in neighboring maybar instrumental watershed by hurni et al. (2005) who obtained surface runoff of 27% of rainfall. groundwater contribution ( gw q ) (18.3%) and deep percolation to the shallow and deep aquifer ( seep w ) (3.3%) are also small proportions, which does not maintain plant water requirement in dry weather condition. the initial soil water content (𝑆𝑊𝑖) is less by 0.2 mm than the final soil water content (𝑆𝑊𝑓), which indicated that the soil moisture status right away before simulation was comparatively drier than soil moisture condition at the end of the simulation. 3.1.1. surface runoff and baseflow of the landscape component of the lake basin the landscape part of the lake basin generated 304.3 mm of annual average surface runoff, which varied from 17.9 https://en.wikipedia.org/wiki/drainage_basin hassen estimating surface water inflow into lake lego 107 mm on forest fields to 708.1 mm on degraded lands over the entire simulation period. runoff is the major (76.8%) streamflow component, while it accounts the second largest proportion (27.6%) of rainfall. catchments that are smaller than 1000 km2 have runoff coefficients of less than 30% (nyssen et al., 2004; hurni et al., 2005). high runoff is generated in july and august (figure 4) in major rainy seasons where agricultural soils are denuded and are easily detached by raindrop impact and transported with runoff to the receiving lake. figure 4. monthly rainfall and simulated surface runoff in lake lego basin. baseflow is fed by 30 ephemeral stream channels and ankerkah periodic river that link the watershed and the lake hydrologically. with respect to location, runoff is high in the northern, southwestern, central west and along ankerkah river below tibina bridge (figure 5), because these areas are degraded lands characterized by 80% of hydrologic soil group “d”. the baseflow contribution (23.2%) to the downstream lake water is generally low. baseflow is extremely low in degraded lands and farmlands (0.0‒13.0%) as compared to vegetated areas (13–44%) where runoff is taken place in reverse. generally, landscape part of the lake basin generate low cumulative annual water inflow due to high but short-lived runoff during rainfall seasons and low groundwater flow during the rest of the year. analogues to this study, tibebe tigabu et al. (2018), in his work of streamflow time series in the lake tana basin, resulted in decadal mean water level decrease due to surface water inflow reduction between the 1990s and 2000s. however, there was significant variation in mean annual streamflow and lake water level from decade to decade. figure 5. surface runoff and baseflow spatial distribution in the lake basin. 0 100 200 300 400 500 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 m o n th ly ra in fa ll a n d s u rf ac e r u n o ff (m m ) time in month (2012 to 2017) precipitation surface runoff hassen east african journal of sciences volume 16(2): 101-114 108 lake lego watershed size (small and fan-shaped) and degradability may make baseflow liable to shrink. in addition, change in streamflow (runoff and baseflow) could link to land use types and constant transformation (for e.g., farmlands constituted 45% and increased at the rate of +19.2% in 2017). information on surface runoff or baseflow of lakes is important to improve land use condition and agricultural water management that alleviate decreasing trends of surface water inflows (international lake environment committee foundation (ilec), 2005). in doing so, figure 5 can provide insight into the availability and distribution of surface runoff and baseflow situations, and can be used to plan and implement intervention measures that enhance hydraulic properties of the soil (bulk density and hydraulic conductivity) which improve streamflow into the downstream lake eventually. 3.1.2. routed streamflow through the stream network in the lake basin the annual average routing of water flows from the lake basin landscape to the lake through 31 outlets marked with red spots (figure 6) were predicted for the simulation period, as depicted in table 2. the mean annual routed streamflow amount into lake lego via the 31 defined stream channels was 21,508,821 m3. moreover, field-slope polygons with no defined channels bordering the lakeshore were clipped (figure 6) and overland runoff generated from them into the lake was calculated. the mean annual overland runoff volume from these polygons was estimated as 475,338 m3. the total mean annual quantity of surface water inflow during the simulation period generated from contiguous landscape of the basin was then 21,984,159 m3 entering each year into the lake, which is equivalent to the mean annual flow of 0.7 m3s–1. figure 6. drainage network, inlet points and field-slope polygons of lake lego basin. hassen estimating surface water inflow into lake lego 109 table 2. average annual streamflow entering lake lego through defined streams. id outlet number sub-basin area (ha) flow (m3 s–1) volume (m3) 1 1 15.6 0.00173 54,639 2 2 27.9 0.00417 131,531 3 3 18.9 0.00306 96,651 4 8 42.7 0.00757 238,851 5 11 15.8 0.00163 51,324 6 19 67.3 0.01186 374,358 7 23 41.9 0.00765 241,471 8 27 23.6 0.00397 125,375 9 31 18.5 0.00347 109,404 10 37 148.6 0.02299 725,675 11 38 20.8 0.00253 79,954 12 39 23.1 0.00397 125,218 13 43 16.6 0.00274 86,488 14 46 16.1 0.00205 64,708 15 105 25.5 0.00306 96,525 16 128 19.6 0.00287 90,528 17 145 26.0 0.00316 99,776 18 150 65.6 0.00816 257,537 19 151 22.8 0.00442 139,453 20 166 16.0 0.00182 57,479 21 169 (ankerkah river) 3216 0.3891 12,281,863 22 188 25.7 0.00265 83,741 23 189 16.5 0.00199 62,814 24 195 42.0 0.00593 187,116 25 206 98.7 0.01168 368,677 26 210 146.1 0.01686 532,182 27 216 (gido stream) 557.8 0.06556 2,069,388 28 217 70.2 0.00734 231,749 29 218 57.9 0.00782 246,805 30 221 (fecha stream) 445.7 0.04955 1,564,036 31 228 (ulaula stream) 178.0 0.02007 633,505 total/average 5,527.4 0.02198 21,508,821 mean monthly simulated streamflow time series graph produced during the simulation period, 2012 to 2017, is drawn in figure 7. hydrographs generated in july, august and september occurred during the main rainy season, were the highest peaks where the 2015 flow peak was relatively low due to drought occurrence. the lowest hydrographs were generated in may and june dry season. figure 7. simulated monthly streamflow time series graph of lake lego basin. 0 100 200 300 400 500 600 700 800 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 s im u la te d st re am fl o w (m 3 ) x 1 0 0 0 0 time in month (2012 to 2017) hassen east african journal of sciences volume 16(2): 101-114 110 3.2. precipitation of the lake basin annual rainfall of the 56-year record (1962−2017) observed at hayq town station was analyzed for a trend. ninety-five percent of rainfall time series were in between +5% and –5% trend boundary lines or very close too (figure 8). five percent of the data scatter was placed above +5% and below -5% trend margin lines due to intraannual variability. for example, in march during the small rainy season and in august in the major rainy season of the 1984 drought year, only 14.4 and 33.6 mm of rainfall were received, respectively. likewise, 2015 was a drought year, and 1962, 1964, 1998 and 2010 were years with abundant rainfall in the basin. figure 8. graphical trend of annual rainfall for lake lego basin. the rainfall trend analysis revealed that there was no distinct tendency in annual rainfall change, except seasonal variability within the observation years. a similar study conducted by tibebe tigabu et al. (2018) in the lake tana basin showed that there was no significant trend in the seasonal and annual basin-wide average rainfall at all observation stations while the mean annual streamflow and lake water level were varying significantly from decade to decade. in aggregate, no trend occurred in rainfall that affected surface water inflow entering the lake during the simulation period of this study. 3.3. implications of low flow regime on lake morphometric parameters the lake is intimately connected with its drainage basin; consequently, the declining flow regime in the lake basin has been affecting the lake size (depth, area and volume). in this study, land use and land cover extent was updated after 10 years of the first land cover analyses carried out by hassen mohammed et al. (2015) (table 3). the long-term study discovered that lake lego surface area was continuously diminishing by 225 ha at the rate of 3.8 ha y– 1 in a 60-year period. table 3. trend in surface area extent of lake lego. year of survey area (ha) number of years between surveys change in area (ha) rate of change (ha y–1) 1957 2430 na na na 1986 2324 29 –107.0 –3.7 2007 2246 21 –78.0 –3.7 2017 2205 10 –41.0 –4.0 total/average − 60 –225.0 –3.8 by substituting the present lake planar area, 2205 ha, into equation 2, which is displayed on figure 9, the current maximum depth (80.4 m) of the lake was estimated. the present lake volume (984,848,192 m3) was calculated with 500 700 900 1100 1300 1500 1700 1900 500 700 900 1100 1300 1500 1700 1900 s e c o n d h al f o f ra in fa ll t im e s e ri e s (m m ) first half of rainfall time series (mm) rainfall time series linear (1:1 line) linear (+5%) linear (-5%) hassen estimating surface water inflow into lake lego 111 surfer golden software using the estimated present depth and past echo-sounder generated three-dimensional grid file built by hassen mohammed et al. (2013). the mean annual surface water inflow (21,984,159 m3) has been primarily causing the volume of the lake to dwindle from 1,007,389,635 m3 surveyed by hassen mohammed et al. (2013) to 984,848,192 m3 in present-day estimate (figure 9), provided that there was no subsurface outflow in the form of seepage through tectonic faults. there are few springs emanating from the same mountain wall the lake water is stored in the west but facing the other side of the lake basin. therefore, the rate of volume reduction was 2,817,680 m3y–1 during the last six successive years (2010 to 2017) of prediction. in other words, the mean annual surface water inflow of 21,984,159 m3 was insufficient to maintain the previous lake water capacity and was affecting morphometric parameters. apportioning the present lake volume decline (2,817,680 m3) by the present lake surface area (22,050,000 m2) at an elevation of 1901.7 m a.s.l would give a depth reduction rate of 0.128 m y–1. consequently, the lake has been constantly shrinking in surface area (3.8 ha y–1) and volume (0.29% y–1). if this scenario continues with the same status and other variables affecting lake basin remain constant, the lake will vanish in 350 years. the water residence time was calculated as the present volume of the lake divided by mean annual water inflow to provide an indication of the average time water spend in the lake. the residence time of lake lego was 45 years, where the longest is 440 years for lake tanganyika and the world average for lakes is 17 years (ilec, 2005). * figure 9. capacity curves – volume and area versus elevation (depth) of lake lego. the amount of annual surface water inflow, 21,984,159 m3, into the lake was generally low when compared to the amount of annual precipitation, 25,047,287 m3, falling over the lake. similar to this result, winter (1995) reported that the inflow of some lakes, with small upstream catchment, is dominated by the precipitation on the lake. studies of tibebe tigabu et al. (2018) and ye et al. (2018) revealed that annual streamflow series of most stations in lake tana and poyang lake, respectively show ‘weaker’ or ‘very weak’ persistence, i.e., the lakes’ basins seem to enter into an increasing process under interdecadal scale, while decreasing under the inter-annual scale. a study by walling and fang (2003) reported that approximately 22% and 9% of the world’s rivers have shown a statistically significant decrease in baseflow and an increase in annual runoff, respectively, where most rivers maintain the status quo. likewise, the lake lego drainage system was generating a nearly constant inflow of water for this mid-term length of analyses period although the inflow amount could not keep the lake morphometric status measured eight years ago. 4. conclusion in this study, the well-established semi-distributed swat model, in combination with geospatial processing tools, was successfully applied to predict surface water inflow into lake lego for the period of six years (2012 to 2017). field measurements, soil laboratory results, climate elements, and geospatial input datasets were used. the major findings were generation of 21,984,159 m3y–1 mean surface water inflow from lake basin into the lake with no 2205 ha 9 8 4 ,8 4 8 ,1 9 2 , m 3 a = –0.09d2 + 362.5d – 36082 r² = 0.9986 0 200 400 600 800 1000 1200 0 500 1000 1500 2000 2500 1821 1826 1831 1836 1841 1846 1851 1856 1861 1866 1871 1876 1881 1886 1891 1896 1901 1906 1911 l ak e v o lu m e i n 1 0 6 m 3 l ak e s u rf ac e a re a (h a) lake depth (m) area volume poly. (area) poly. (volume) d=80.4 m hassen east african journal of sciences volume 16(2): 101-114 112 long-term trend for the simulation period while the lake water volume has been reducing at the rate of 2,817,680 m3y–1. the mean annual water inflow is insufficient to maintain the existing lake volume capacity and affecting lake morphometric parameters such as its depth, surface area, and volume to shrink at the rate of 0.128 m y–1, 3.8 ha y–1 and 0.29% y–1, respectively. the results indicated the need for integrated participatory lake basin management to increase annual streamflow into the lake to maintain its storage capacity. hydrogeologic studies need to be conducted in the future to bridge the remaining knowledge gaps by investigating subsurface outflow losses from the lake through tectonic faults and other outflows. 5. acknowledgements the author is grateful to wollo university for covering soil laboratory expenses. the author thanks the ministry of water, irrigation and energy and wollo 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(eds.). physics and http://directives.sc.egov.usda.gov/ hassen east african journal of sciences volume 16(2): 101-114 114 chemistry of lakes. 1stedition, springer, berlin, heidelberg, germany. wischmeier, w.h. and smith, d.d. 1978. predicting rainfall‒erosion losses: a guide to conservation planning. agriculture handbook no 282. usdaars, washington dc. pp. 66. ye, x., xu, c.y., li, x. and zhang, q. 2018. comprehensive evaluation of multiple methods for assessing water resources variability of a lake–river system under the changing environment. hydrology research, 48: 332−343. zalewski, m. and robarts, r. 2003. ecohydrology – a new paradigm for integrated water resources management. sil news, supplement, 40: 1–5. ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(1): 77–92 licensed under a creative commons *corresponding author: atinkut947@gmail.com attribution-noncommercial 4.0 international license. genotype x environment interaction and grain yield stability of improved teff [eragrostis tef (zucc.) trotter] varieties in northwestern ethiopia atinkut fentahun1*, tiegist dejene2, and kebebew assefa3 1adet agricultural research center, amhara regional agricultural research institute, p.o. box 08, bahir dar, ethiopia 2college of agriculture and environmental science, bahir dar university, p.o. box 79, bahir dar, ethiopia 3debre zeit agricultural research center, ethiopian institute of agricultural research, p.o. box 32, debre zeit, ethiopia abstract background: teff is an important staple cereal crop in northwestern ethiopia. however, the yield of the crop is very low due to, among others, lack of stable and high yielding varieties under varying environmental conditions because of genotype x environment interaction effect. objective: the study was conducted to assess the effect of genotype by environment interaction, identify mega environments, and select high yielding and stable teff genotypes that interact less with the changing environment. materials and methods: twenty improved teff varieties were evaluated using a randomized complete block design with three replications at adet, motta, bichena, debre-tabor and takussa districts for two consecutive years. data were collected on days to heading and maturity, plant height, grain filling period, panicle and culm length, dry plant biomass and grain yield. the data were analyzed using a combined analysis of variance and genotype main effect plus genotype by environment interaction biplot. results: the combined analysis of variance for grain yield revealed highly significant (p < 0.001) effects for genotype (16%), environment (54%) and genotype x environment interaction (23%). the effect of environment was three times higher than that of genotype, indicating significant and undesirable influence of the environment on genotype stability. the mean grain yield across the environments ranged from 1.65 to 2.77 tons ha–1 for debre-tabor and takussa, respectively. the genotype mean yield ranged from 1.68 to 2.51 tons ha–1 for simada and hiber-1, respectively. genotype by environment interaction biplot analysis grouped the ten test environments and twenty genotypes into three mega-environments and four genotype groups. besides, adet district and bichena district had relatively the longest vector length and the smallest angles with the average environmental axis, thus being the most representative of all environments. regarding genotypes, hiber -1 followed by kora, etsub and dukem were identified as the best yielding and relatively stable genotypes to increase teff productivity in the region. conclusion: the biplot analysis of the genotype by environment interaction resulted in the identification of adet and bichena districts as the most favorable locations for teff production and as well as hiber-1 as the most productive teff variety for cultivation in the study area. this implies that farmers in the two districts could be advised to take up this variety for enhancing yield of the crop and income from its production. keywords: combined analysis; environmental axis; genotypes; genotype main effect; genotype x environment interaction; grain yield stability atinkut et al. east african journal of sciences volume 16(1): 77–92 78 1. introduction teff is an important staple cereal crop in ethiopia as well as in amhara national regional state, particularly in northwestern ethiopia. in ethiopia, the crop covers 3.02 million hectares per year and accounts for 30% of the total land allotted to cereals. it is second in total production (5.28 million tons) accounting for 20% of grain production among all cereals grown, while its national average productivity is 1.75 tons ha–1 (central statistical agency (csa), 2018). in amhara national regional state (anrs), teff productivity (1.8 tons ha–1) is slightly more than the national average (csa, 2018). amhara region (northwestern part of ethiopia) is one of the major teff growing areas in the country. according to csa (2018), the contribution of the region in terms of area coverage and total production is about 38% and 39%, respectively. in spite of the importance of the crop, both the national and regional average yields are very low as compared to other cereals grown in ethiopia as well as the crop’s genetic potential. a study conducted under non-lodging condition has demonstrated that yield potential of the crop can further be increased up to 4.6 tons ha–1 (yifru teklu and hailu tefera, 2005). this shows there is higher difference between the potential of the crop and the actual yield, which is less than half. some of the factors contributing to the low yield of teff include low soil fertility, lack of high yielding and widely adaptable varieties, weeds, erratic rainfall distribution in lower altitudes, lodging, waterlogging, and low moisture (fufa hundera, 1998). among these factors, scarcity of stable and high yielding teff varieties under varying environmental conditions due to gei effect is the main factor. the occurrence of genotype by environment interaction is the basic cause for differences among genotypes in terms of grain yield stability. stability analysis can help to characterize the response of varieties to the changing environments and to determine the best and representative locations of the environmental diversity (mohammed et al., 2008). hence, conducting experiments in several locations and seasons are needed to determine stable and high yielding varieties of the crop. multi-environment trials (met) are carried out to evaluate grain yield stability performance of genetic materials under varying environmental conditions (delacy et al., 1996; farshadfar et al., 2012). consequently, genotype x environment effects can be revealed by multienvironment trial experiments. the presence of a significant genotype x environment interaction for quantitative traits such as grain yield can lead to the failure of genotypes to achieve the same relative performance in different environments (fekadu gurmu et al., 2009). information on genotype x environment interaction (gei) leads to successful identification of stable genotypes, which could be used for wider cultivation. yield is a complex quantitative character greatly influenced by environmental fluctuations; hence, the selection of superior genotypes based on grain yield performance at a single location in a year would not be very effective (shrestha et al., 2012). thus, evaluation of genotypes for stability of performance under varying environmental conditions for yield has become an essential part of any plant breeding program. moreover, understanding of genotype x environment interaction enables us to effectively allocate resources and to characterize genotypic responses to diverse crop productivity levels (tiruneh kefyalew et al., 2000). thus, it enables to eliminate unnecessary spatial and temporal replications of yield trails as well as to establish additional testing environments when the existing ones are under represented (basford and cooper, 1998). even though some studies have been conducted to elucidate the g x e interaction of teff in other parts of the country, there is little information on the g x e interaction of teff varieties in diverse environmental conditions of north western ethiopia. the importance of conducting more studies across major teff growing environments has been suggested by mathewos ashamo and getachew belay (2012), so as to enable breeders to identify adaptable, stable, and high yielding teff genotypes. therefore, the objectives of the present study were to assess the effect of gei and identify megaenvironments, and to select high yielding and stable teff genotypes that interact less with the changing environment in northwestern ethiopia. atinkut et al. genotype x environment interaction and yield stability of teff 79 2. materials and methods 2.1. description of the study area a field experiment was conducted in five locations during the 2018 and 2019 main cropping seasons under rain-fed condition. the test locations were adet (yilmana-densa), motta (hulet-eju-enesie), bichena (enemay), debretabor, and takusa districts (figure 1). the climatic, edaphic and geographic descriptions of the locations are different and presented in table 1. figure 1. map of amhara national regional state showing the testing sites. table 1. description of the locations and seasons. test environments altitude (m.a.s.l.) geographical location soil type weather data code name latitude longitude rainfall (mm) temperature (°c) max. min. e1 debre-tabor-2018 2591 11051'n 38001'e luvisol 1609.5 22.5 9.5 e2 adet –2018 2240 11016' n 37029' e nitosol 1432.0 25.6 10.8 e3 motta–2018 2470 11020'n 37088' e nitosol 1334.0 23.8 10.5 e4 bichena–2018 2541 10046'n 38019'e vertisol 1186.0 24.4 11.1 e5 takussa–2018 1840 12010'n 37006' e vertisol 870.0 15.0 28.0 e6 debre–tabor-2019 2591 11051'n 38001'e luvisol 1926.1 22.7 10.0 e7 adet–2019 2240 11016' n 37029' e nitosol 1591.8 25.9 11.1 e8 motta–2019 2470 11020'n 37088' e nitosol 1457.5 24.1 11.4 e9 bichena–2019 2541 10046'n 38019'e vertisol 1126.4 23.5 10.7 e10 takussa–2019 1840 12016'n 37006' e vertisol na na na note: m.a.s.l. = meter above sea level; e = east; n = north; max. = maximum; min. = minimum; and na = not available for the specified periods. weather data were collected from west amhara meteorological cervices center (2018 and 2019), and edaphic information’s were obtained from the respective research centers. 2.2. plant materials twenty teff varieties released for cultivation in ethiopia were used in this study (table 2). the varieties were deliberately collected based on their phenology, adaptation, yield performance, and seed color, to select high yielding and stable teff genotypes that interact less with the changing environment in north western ethiopia (table 2). atinkut et al. east african journal of sciences volume 16(1): 77–92 80 2.3. treatments and experimental management the treatments consisted of 20 genotypes (table 2) and ten environments (locations) (table 1). the experiment was laid out as a randomized complete block design and replicated three times per treatment. each plot consisted of six rows with 2 m length and 0.2 m spacing between rows. the spacing between blocks and plots were 1.5 m and 1 m, respectively. land was prepared according to the conventional practice. it was ploughed five times using oxen before planting and the plot after the last ploughing was used for sowing. planting was done from the beginning to end of july depending on the recommendations for the different test locations. sowing was done by hand drilling using seeding rate of 15 kg ha– 1. a blanket recommendation rate of urea and di ammonium phosphate (dap) were applied to the plots at the rate of 40/60 n/p2o5 ha–1 for nitisols and luvisols and 60/60 n/p2o5 ha–1 for vertisols. all of the dap was applied at planting but urea was top dressed at tillering stage. all other pre-and post-planting management practices were made as per the recommendations for teff husbandry in all test locations. 2.4. data collection data were collected on plant, row and plot basis. five randomly taken plants were selected from the central four rows for plant-based parameters. the entire six rows in the plot were used for plot-based data scoring whereas four central rows were used for row-based data scoring. plant height, panicle length, and culm length were recorded on plant basis. shoot dry biomass and grain yield were recorded on row basis whereas days to heading and days to maturity, grain filling period were recorded on whole-plot basis. table 2. descriptions of teff genotypes used for the study. genotype id year of release suitable environment seed color breeding center grain yield (tons ha–1) research station farmers’ field wellenkomi (dz-01-787) g1 1978 hp pale white debre-zeit 2.4-3.0 2.0-2.4 tsedey (dz-cr-37) g2 1984 lw white debre-zeit 1.8-2.5 1.4-2.2 dukem (dz-01-974) g3 1995 hp pale white debre-zeit 2.4-3.4 2.6-2.7 ziquala (dz-cr-358) g4 1995 hp white debre-zeit 17-24 16-22 ambo toke (dz-01-1278) g5 2000 hp white holeta 2.4-3.5 na dega-tef (dz-01-2675) g7 2005 hp pale white debre-zeit 1.5-2.2 1.6-2.0 quncho (dz-cr-387ril355) g8 2006 hp very white debre-zeit 2.0-3.2 1.8-2.6 etsub (dz-cr-3186) g9 2008 hp white adet 1.9-2.7 1.6-2.2 simada (dz-cr-285ril295) g10 2009 lw white debre-zeit 1.9-2.8 1.6-2.5 boset (dz-cr-40ril-50d) g11 2012 lw very white debre-zeit 1.8-2.0 1.4-1.8 kora (dz-cr-438ril-133b) g12 2014 hp very white debre-zeit 2.5-2.8 1.8-2.2 were-kiyu (acc.21476a) g13 2014 lw white sirinka 2.22 na abola (dz-cr-438(ril7) g14 2015 hp white adet 2.0-2.8 1.46-1.68 dagim (dz-cr-438-ril91a) g15 2015 hp white debre-zeit 2.5-2.8 1.8-2.3 areka-1(dz-01-974*dz-012788) g6 2017 lw white areka 1.6-1.87 1.6-1.75 negus (dz-cr-429ril125) g16 2017 hp very white debre-zeit 2.8 na felagot (dz-cr-442ril77c) g17 2017 hp brown debre-zeit 2.54 na tesfa (dz-cr-457-ril181) g18 2017 hp very white debre-zeit 2.5 na hiber-1 (dz-cr-419) g19 2017 lw white adet 1.7-2.7 1.46-2.08 abay (acc#225931) g20 2018 hp white adet 2.5-3.5 1.8-2.2 note: id = identification; hp = high potential; lw = low moisture; and moa = ministry of agriculture. na = not available. genotypes were obtained from moa (2006–2018) and variety releasing centers. atinkut et al. genotype x environment interaction and yield stability of teff 81 2.5. data analysis analysis of variance for grain yield and yield related traits was carried out for each location separately using proc glm model of sas computer program (sas institute, 2002). duncan’s multiple range tested was used for mean separation. the combined analysis of variance across locations was done using proc glm with mixed procedure of sas software which corresponds to the statistical model. genotype effects were assumed to be fixed and environmental effects as random. to determine the validity of the combined analysis of variance, the homogeneity of error variance between environments were performed based on the ratio of the larger mean square of error (mse) from the separate analysis of variance to the smallest mean square of error as: f– ratio = large mse small mse if the larger error mean square was not three-fold larger than the smaller error mean square, the error variance was considered homogeneous (gomez and gomez, 1984). genotype by environment interaction was quantified using pooled analysis of variance, which partitions the total in to its component parts (genotype, environment, genotype x environment interaction and pooled error). the following statistical model was used for anova of data of the individual environments: yij = μ + gi + bj + ɛij where, yij = observed value of genotype i in block j; µ = grand mean of the experiment; gi = effect of genotype i; bj = the effect of block j; and, ɛij = error effect of genotype i in block j. in performing the combined analysis of variance, genotypes were assumed to be fixed while replications with in environments were assumed random. the following statistical model was used for combined analysis of variance over locations: yijk = μ + gi + ej + geij +bkj+ ɛijk where, yijk = observed value of genotype i in block k of environment (location) j, µ = grand mean, gi = effect of genotype i, ej= environment or location effect, geij = the interaction effect of genotype i with environment j, bkj = the effect of block k in location (environment) j, and ɛijk = error (residual) effect of genotype i in block k of environment j. the combined analysis of variance was carried out to estimate the additive main effects of environment, genotype and gei. significance levels of these components were determined by using f-tests. whenever the f-test was found significant, genotype x environment interaction was described using gge biplot analysis (yan et al., 2000) using genstat analytical software version 18 (vsn international, 2015). genotype main effect plus genotype x environment interaction biplot model (yan et al., 2000) is the most commonly used and more efficient in determining the most stable and high yielding genotypes in multi-environment trials as compared to the earlier procedure (eberhart and russell, 1966; ammi model, guach and zobel, 1988). the gge biplot allows visual examination of the relationships among the test environments, genotypes and genotype x environment interactions. thus, the first two principal components (pc1 and pc2) were used to graphically represent the gei, and to identify the rank of the test genotypes and environments (yan et al., 2000). gge biplot analysis was based on the simplified model with two principal components (yan et al., 2000). the model was: yij–yij + l1xi1hj1 + l2xi2hj2 + εij in which, yij is the productivity mean of cultivar i in environment j, yij is the general mean of the cultivars in environment j, l1 xi1 hj1is the first principal component (pca1), l2 xi2 hj2 is the second principal component (pca2), l1 and l2 are the eigenvalues associated with pca1 and pca2, respectively, xi1and xi2 are the values of the first and second principal components, respectively, for cultivar i, hj1 and hj2 are the values of the first and second principal components, respectively, for environment j, and εij is the error ij associated with the model. atinkut et al. east african journal of sciences volume 16(1): 77–92 82 3. results and discussion 3.1. analysis of variance variance of homogeneity from results of the quick bartlett test revealed that the mean squares of individual locations were homogenous for grain yield. thus, the combined analysis of variance for gain yield of 20 improved teff varieties at ten environments showed highly significant (p < 0.001) effects of genotypes, environments and genotype x environment interaction (table 3). environments accounted for 54% of the total variation followed by the gei (23%) whereas the genotype alone accounted 16% (table 3). habte jifar et al. (2019) reported similar findings in teff multi-environment trials, where the largest proportion of total variation was attributed to locations and relatively smaller effects were noted due to genotype and genotype and environment interaction (gei). sewagegne tariku et al. (2018) also found similar results in which environments contributed about 91% of the total variation in grain yield of teff, while genotypes and gei accounted for about 0.87% and 3.63%, respectively. the high percentage of the environment sum squares is an indication that the major factor that influence yield performance of teff genotypes is the environment. besides, the environmental effect was found to be highly significant. this may indicate presence of significant differences among testing locations due to variation in temperature, soil type, rainfall, and other environmental factors as also reported by legesse kassa et al. (2006). table 3. combined anova for grain yield (ton ha–1) of genotypes tested at five environments during 2018 and 2019 cropping seasons. source of variation degrees of freedom sum of squares percent of total explained mean squares pr > f blocks (environments) 20 1.4323 0.925 0.072 <.0001 environment 9 82.75 53.47 9.194 <.0001 genotype 19 25.39 16.41 1.336 <.0001 genotype × environment 171 35.58 22.99 0.20807 <.0001 residuals 380 9.61 6.21 0.02529 total 599 154.76 100 mean 2.16 coefficient of determination (r2) 0.94 coefficient of variation (%) 7.36 the large sums of squares associated with the environment in the present study indicate that the selected test environments were agro-ecologically diverse. this signifies the importance of site selection for teff cultivation. the mean grain yield across environments ranged from 1.65 tons ha–1 for debre-tabor to 2.77 tons ha–1 for takussa. on the other hand, the grain yield means of the genotypes ranged from 1.68 to 2.51 tons ha–1 for simada and hiber-1, respectively. takusa and bichena were relatively high yielding environments compared to debre-tabor, motta and adet. the variety hiber-1 performed best in most of the environments (locations) followed by the varieties etsub and kora. apart from this, the teff varieties with higher grain yield at specific location respectively, were: hiber-1, dagim and etsub at adet; kora, hiber-1 and dukem at bichena; etsub, hiber-1 and kora at takussa; worekiyu, wellenkomi and filagot at motta; and etsub, dukem and wellenkomi at debre-tabor (table 4). the high variability in grain yield among the twenty teff varieties at the ten environments might be due to wide variability in climatic and soil conditions. similarly, inconsistent grain yield performances of teff varieties have been found across locations (solomon chanyalew et al., 2009; ayalneh tilahun et al., 2012; mathewos ashamo and getachew belay, 2012; wendwosen shiferaw et al., 2012; sewagegne tariku et al., 2018; habte jifar et al., 2019). atinkut et al. genotype x environment interaction and yield stability of teff 83 table 4. mean grain yield ton ha–1 of twenty teff genotypes for individual environments during the 2018 and 2019 main cropping seasons. variety 2018 2019 overall mean rank d/t adet motta bichena takusa d/t adet motta bichena takusa wellenkomi 2.18bc 2.38cde 2.12 a 2.93bc 2.36de 1.99bc 1.77fg 2.21ab 2.53abc 2.31defg 2.28 5 tsedey 1.25h 1.95fg 1.98abc 2.35e 2.55cd 1.32j 2.03cde 1.94cdef 1.72f 2.29defg 1.94 17 dukem 2.29b 2.29cde 1.78cde 3.13b 3.03ab 2.10ab 2.21abcd 1.78efg 2.85a 2.33def 2.38 4 ziquala 1.62efg 2.24def 1.59e 2.53de 2.46cde 1.48fghi 2.00de 1.70g 1.92ef 2.28defg 1.98 15 ambotoke 1.85de 2.59bc 1.94abcd 2.80bcd 3.05ab 1.53fgh 2.02de 2.01cbd 2.34bcd 2.22efg 2.24 7 areka-1 1.72ef 2.12efg 1.67de 1.75f 2.90ab 1.89c 1.73gh 1.71g 1.86f 2.36cde 1.97 16 dega-tef 2.18bc 2.19ef 1.94abcd 2.82bcd 1.87f 1.93c 2.08cde 1.96cdef 2.72ab 1.89i 2.16 9 quncho 1.96cd 2.53bcd 1.80bcde 2.96bc 3.03ab 1.60def 2.11bcd 1.89cdefg 2.61abc 2.10ghi 2.26 6 etsub 2.52a 2.81ab 1.79bcde 2.94bc 3.20a 2.23a 2.20abcd 1.87cdef 2.60abc 2.64a 2.48 2 simada 1.27h 1.57h 1.65e 1.96f 2.93ab 1.36ij 1.63gh 1.24h 1.08g 2.12fgh 1.68 19 boset 1.49fgh 2.29cde 1.93abcd 2.88bc 2.88ab 1.39hij 2.00de 1.74fg 2.35bcd 2.57abc 2.15 10 kora 1.99cd 2.56bcd 1.97abc 3.46a 3.03ab 1.70de 2.26abc 1.96cdef 2.91a 2.46abcd 2.43 3 werekiyu 1.71ef 2.38cde 2.16a 2.77cd 2.13ef 1.56ef 2.00def 2.27a 2.36bcd 2.15efgh 2.15 11 abola 1.68ef 2.29cde 1.97abc 2.88bc 2.37de 1.41ghij 1.99def 1.83defg 2.62abc 2.11fghi 2.12 13 dagim 1.58fg 2.80ab 1.74cde 2.72cd 2.72bc 1.55fg 2.32ab 1.89cdefg 2.58abc 2.45abcd 2.24 7 negus 1.52fg 2.82ab 2.00abc 2.91bc 2.39cde 1.52fgh 2.15bcd 2.02bcd 1.86f 2.17efgh 2.13 12 felagot 1.39gh 2.12efg 2.06ab 2.93bc 3.12a 1.72d 2.20abcd 1.88cdefg 2.26cde 2.37bcde 2.21 8 tesfa 1.27h 1.86g 1.82bcde 2.29e 3.08ab 1.34ij 1.51h 1.81defg 1.32g 1.99hi 1.83 18 hibir-1 1.97cd 2.94a 1.99abc 3.15b 3.17a 1.97bc 2.39a 2.08abc 2.89a 2.58ab 2.51 1 abay 1.41gh 2.11efg 1.98abc 2.86bcd 3.07ab 1.36ij 1.84efg 1.97cde 2.02def 2.21efgh 2.08 14 mean 1.74 2.34 1.89 2.75 2.77 1.65 2.02 1.89 2.27 2.28 2.16 sem (+) 0.076 0.098 0.084 0.105 0.108 0.0523 0.082 0.078 0.133 0.244 cv (%) 7.59 7.23 7.71 6.63 6.73 5.49 703 7.15 10.17 5.85 note: means in the same column followed by the same letters are not significantly different at p < 0.05 using duncan’s multiple range test. d/t = debre-tabor. cv = coefficient of variation and sem =standard error of the mean. atinkut et al. east african journal of sciences volume 16(1): 77–92 84 3.3. stability analysis and mega-environment classification using gge biplot 3.2.1. the “which-won-where” pattern the analysis of variance showed the presence of highly significant g x e mean squares for grain yield across the test environments. this result indicates that the use of the gge biplot would be pertinent to decompose the g x gei effects. the principal component axis1 (pc1) and axis 2 (pc2), are cumulatively, explained 68% of the total variation for grain yield (figure 2). this result suggests that the biplot graphics explained most of the sums of squares for genotype by environment interaction. this outcome made it possible to have a safe genotype selection based on the multivariate analysis as per the suggestions of yan (2001). the varieties and the environments found inside the polygon were less responsive to environment stimuli (figure 2). environments grouped inside the same polygon had similar influence on the genotypes. environment groups deriving from the ten assessed environments revealed three mega-environments. the first one encompassed takusa and debre-tabor areas with genotypes etsub and hiber-1 presented in the vertex. the second mega-environment contains adet and bichena areas and the third mega-environment contains only one location which is motta with the vertex genotype werkiyu (figure 2). related to this result, karimizadeh et al. (2013), yirga belay (2016) and sewagegne tariku et al. (2018) identified different lentil, sesame and tef varieties, respectively, growing on mega environments. in the polygon view of the biplot analysis, the genotypes and test environments fell into four and three sectors, respectively. varieties from the polygon vertex that did not group in any one of the environments were not fit varieties for the tested environment. the vertex variety simada (g10) and tesfa (g18) had no corresponding environment and hence have the lowest mean grain yield across environments (figure 2). habte jifar et al. (2019) similarly reported non fit varieties for the tested environments in teff gge biplot analysis. figure 2. polygon views of the gge-biplot based on symmetrical scaling for the which-won-where pattern analysis for varieties and environments (e1 = debre-tabor year-1, e2 = adet year-1, e3 = motta year-1, e4 = bichena year-1, e5 = takusa year-1, e6 = debre-tabor year-2, e7 = adet year-2, e8 = motta year-2, e9 = bichena year-2, e10 = takusa year-2, g1 = wellenkomi, g2 = tseday, g3 = dukem, g4 = ziquala, g5 = ambotoke, g6 = areka-1, g7 = dega-tef, g8 = quncho, g9 = etsub, g10 = simada, g11 = boset, g12 = kora, g13 = werekiyu, g14 = abola, g15 = dagim, g16 = negus, g17 = flagot, g18 = tesfa, g19 = hiber-1, and g20 = abay). atinkut et al. genotype x environment interaction and yield stability of teff 85 3.2.2. evaluation of genotypes relative to ideal genotypes a genotype which is found at the center of the concentric circle is considered as an ideal genotype for teff grain production with its high mean yield and consequently stable characteristics, and genotypes that are close to the ideal genotype are considered as good genotypes (figure 3). accordingly, hiber-1 (g19) being at the center of the concentric circle can be considered as an ideal genotype for teff grain production with high mean yield and stable characteristics. likewise, kora (g12), etsub (g9) and dukem (g3) that were close to the ideal genotypes are considered as good genotypes based on their yield performance as well as stability. on the other hand, simada (g10), tesfa (g18), tseday (g2) and areka1(g6) which are located farther from the first concentric circle are undesirable and low yielding genotypes (figure 3). these results are confirmed by the mean separation test discussed earlier in table 4. similarly, sewagegne tariku et al. (2020) identified variety hebir-1 is the most ideal genotype for teff grain production in teff variety verification trials. the relative contribution of stability and grain yield for identifying desirable genotype found in this study by the ideal genotype procedure of gge biplot were also similar to fan et al. (2007) maize hybrids stability studies. figure 3. gge-biplot based on genotype-focused scaling for comparison the genotypes with the ideal genotype (e1 = debre-tabor year-1, e2 = adet year-1, e3 = motta year-1, e4 = bichena year-1, e5 = takusa year-1, e6 = debre-tabor year-2, e7 = adet year-2, e8 = motta year-2, e9 = bichena year-2, e10 = takusa year-2, g1 = wellenkomi, g2 = tseday, g3 = dukem, g4 = ziquala, g5 = ambotoke, g6 = areka-1, g7 = dega-tef, g8 = quncho, g9 = etsub, g10 = simada, g11 = boset, g12 = kora, g13 = werekiyu. g14 = abola, g15 = dagim, g16 = negus, g17 = flagot, g18 = tesfa, g19 = hiber-1, and g20 = abay). 3.2.3. interrelationship among environment in gge biplot, the cosine of the angle between any environment vectors stands for correlation intensity. less than 90° indicates a positive correlation, more than 90° indicates a negative correlation and close to 90° indicates no correlation (yan and kang, 2003). the angle between the vectors of two environments has a meaningful relation with the correlation coefficient between them (yan, 2002; yan and kang, 2003) and such a relationship is used to group the test environments. thus, if two environments are positively correlated, the best yielding genotypes in one environment will perform best in the other environments. in contrast, if two environments are negatively correlated, the best yielding genotypes in one atinkut et al. east african journal of sciences volume 16(1): 77–92 86 environment perform the least in the other environment and vice versa (yan, 2002; yan and kang, 2003). in the present study, as shown on figure 4, adet, debretabor and bichena with an angle less than 90o are positively correlated with each other. on the other hand, takussa and motta environments had greater than 90o angle and hence have negative correlations. figure 4. gge-biplot based on environment-focused scaling for environments (e1 = debre-tabor year-1, e2 = adet year-1, e3 = motta year-1, e4 = bichena year-1, e5 = takusa year-1, e6 = debre-tabor year-2, e7 = adet year-2, e8 = motta year-2, e9 = bichena year-2, e10 = takusa year-2, g1 = wellenkomi, g2 = tseday, g3 = dukem, g4 = ziquala, g5 = ambotoke, g6 = areka-1, g7 = dega-tef, g8 = quncho, g9 = etsub, g10 = simada, g11 = boset, g12 = kora, g13 = werekiyu. g14 = abola, g15 = dagim, g16 = negus, g17 = flagot, g18 = tesfa, g19 = hiber-1, and g20 = abay). 3.2.4. evaluation of environments relative to ideal environments an ideal environment should satisfy two conditions at the same time. these distinctly differentiate and discriminate the genotypes, and the representativeness for the target environments (yan, 2010). discriminating refers to an environment’s ability to maximize the variance among candidate genotypes in a study (blanche and myers, 2006). an ideal trial site can effectively screen genotypes that have high and stable yields. in gge biplot graph, the small circle stands for an ideal environment, which depends on the mean coordinates of all test environments. there has been a positive correlation between the environment vector length and the environment discriminating ability while there has been negative correlation between the angle existing in environment vector with the ideal environment and the environment’s representativeness of the target environment (yan, 2010). accordingly, figure 5 shows that the discriminating ability and the best representative environments for teff varieties was in declining order e2 (adet year-1), followed by e7 (adet year-2), e9 (bichena year-2), e4 (bichena year-1), e1 (debre-tabor year-1), e6 (debre-tabor year-2), e8 (motta year-2), e3 (motta year-2), e10 (takusa year-2), and e5 (takusa year-1). a test environment having a small angle with the average environmental axis is said to be more representative of other test environments (yan and tinker, 2006). in the present study, therefore, adet (e2) which fell into the center of concentric circle and had the longest vector length and the smallest angle with the average environmental axis was identified to be the most atinkut et al. genotype x environment interaction and yield stability of teff 87 representative of all test environments. hence, adet and bichena are relatively ideal locations for teff cultivation among the test environments. in agreement with this finding, habite jifar et al. (2019) reported that adet and axum are relatively representative environments among test environments for teff production, but on the contrary, same researchers reported that they were not discriminative environments. mahdieh et al. (2016) also reported that a testing environment has less power to discriminate genotypes when located far away from the center concentric circle or to an ideal environment. hence, in connection to our result, motta and takusa testing locations, which are located far away from the center concentric circle, are considered as less powerful to discriminate genotypes. figure 5. gge-biplot based on environment-focused scaling for comparison of environment with the ideal environments (e1 = debre-tabor year-1, e2 = adet year-1, e3 = motta year-1, e4 = bichena year-1, e5 = takusa year-1, e6 = debretabor year-2, e7 = adet year-2, e8 = motta year-2, e9 = bichena year-2, e10 = takusa year-2, g1 = wellenkomi, g2 = tseday, g3 = dukem, g4 = ziquala, g5 = ambotoke, g6 = areka-1, g7 = dega-tef, g8 = quncho, g9 = etsub, g10 = simada, g11 = boset, g12 = kora, g13 = werekiyu. g14 = abola, g15 = dagim, g16 = negus, g17 = flagot, g18 = tesfa, g19 = hiber-1, and g20 = abay). 3.3.5. mean grain yield and stability performance of genotypes ranking of twenty teff varieties based on mean yield performance and stability is presented in figure 6. the single arrow line passing through the biplot origin and the average environment indicated by the small circle is the average environments coordinate (aec) axis, which is defined by the average pc1 and pc2 scores of all environments (yan and kang, 2003). this line points towards higher mean yield across environments. hence, in the present biplot, g19 gave the highest mean yield followed by g9, g12, g3, g1, g8, g5, g15 and g17. the remaining genotypes had bellow grand mean yield (figure 6). in lien with this result sewagegne tariku et al. (2020) reported that hiber-1 is the highest mean grain yield and relatively stable variety in teff variety verification trial. the line which passes through the biplot origin and perpendicular to the aec axis shows the measure of stability. either direction away from the biplot origin, on this axis, indicates greater genotype x environment interaction and poor stability or vice versa (kaya et al., 2006). thus, in terms of stability the genotypes ranked as g17 > g12 > g18 > g8 > g5 > g19 > g11 > g20 > atinkut et al. east african journal of sciences volume 16(1): 77–92 88 g2 > g15 > g4 > g14 > g3 > g16 > g1 > g7 > g9 > g6 > g10 > g13 (figure 6). stability was reported to have lower heritability than mean performance (eskridge, 1996) hence; it is useful only when considered jointly with mean performance. yan and tinker (2006) also noted that stability refers to the relative performance of a genotype and it is meaningful only when associated with mean performance. figure 6. gge-biplot based on environment-focused scaling for comparison of environment with the ideal environments (e1 = debre-tabor year-1, e2 = adet year-1, e3 = motta year-1, e4 = bichena year-1, e5 = takusa year-1, e6 = debretabor year-2, e7 = adet year-2, e8 = motta year-2, e9 = bichena year-2, e10 = takusa year-2, g1 = wellenkomi, g2 = tseday, g3 = dukem, g4 = ziquala, g5 = ambotoke, g6 = areka-1, g7 = dega-tef, g8 = quncho, g9 = etsub, g10 = simada, g11 = boset, g12 = kora, g13 = werekiyu. g14 = abola, g15 = dagim, g16 = negus, g17 = flagot, g18 = tesfa, g19 = hiber-1, and g20 = abay). atinkut et al. genotype x environment interaction and yield stability of teff 89 4. conclusions analysis of gei is necessary to determine the stability and performance of varieties across different environments. the results of the combined analysis of variance in this study have demonstrated that teff grain yield and plant height, panicle length, dry biomas, days to heading and maturity were significantly affected by environment (e), followed by g x e interaction and genotype (g) effects, respectively. the results of the research revealed that the varieties hiber-1 (g19), kora (g12), etsub (g9) and dukem (g3) were found to be good genotypes based on their yield performance as well as stability. on the other hand, simada (g10), tesfa (g18), tseday (g2) and areka-1(g6) were found as unstable and low yielding genotypes. thus, hiber-1 could be recommended for wide cultivation across the areas of north western ethiopia because of its high yield potential and yield stability. the results have also demonstrated that the variety kora for bichena, etsub for debre-tabor and takusa and werekiyu for motta could be potentially productive for specific adaptation to boost grain production of the crop. furthermore, the present study revealed the existence of three megaenvironments and four teff genotype groups in north western parts of ethiopia. environment, adet, and bichena have the longest vector length and the smallest angle with average environmental axis was the most discriminating and representative of all test environments, respectively. it could, thus, be concluded that adet and bichena districts are the best locations for teff production and hiber-1 is the best teff variety to be produced in the region. 5. acknowledgements the authors are grateful to adet agricultural research center for providing financial supports and teff breeding staff of adet and debre-tabor research sub-center for technical supports. 6. references ayalneh tilahun, habtamu zeleke and amsalu ayana. 2012. genetic variability, heritability and genetic advance in tef [eragrostis tef (zucc.) trotter] lines in sinana and adaba. international journal of plant breeding and genetics, 6(1): 40–60. basford, k.e. and cooper, m. 1998. genotype x environment interactions and some considerations of their implications for wheat breeding in australia. australia journal of agricultural research, 49(2): 153–174. blanche, s.b. and myers, g.o. 2006. identifying discriminating locations for cultivar selection in louisiana. crop science, 46 (2): 946–949. csa (central statistical agency). 2018. central statistical agency, agricultural sample survey 2017/2018 (2010 e.c.). report on area and production of major crops (private peasant holdings, meher season), volume i. statistical bulletin 586. addis ababa, ethiopia. pp. 14–18 delacy, i.h., basford, k.e., cooper, m. and bull, j.k. 1996. analysis of multi environment trials and historical perspective. in: cooper, m. and hammer, g.l. eds.). plant adaptation and crop improvement. cab international. eberhart, s.a. and russell, w.a. 1966. stability parameters for comparing varieties. crop science, 6 (1): 36–40. eskridge, k.m. 1996. analysis of multiple environment trials using the probability of outperforming a check. pp. 273–307. in: kang, m.s. and gauch jr. h.g. 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1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (2) 151-162 licensed under a creative commons *corresponding author. e-mail: mitikuguya@yahoo.com attribution-noncommercial 4.0 international license. producing, processing, marketing and hygiene of cow milk in the supply chain of girar jarso district of oromia regional state, ethiopia alemnesh yirda1, mitiku eshetu2*, and firew kassa3 1department of animal sciences, selale university, p.o. box 245, fitche, ethiopia 2school of animal and range sciences, haramaya university, p.o. box 138, dire dawa, ethiopia 3holetta agricultural research center, p.o. box 31, holetta, ethiopia abstract background: production and productivity of dairy is very low in ethiopia. this problem is exacerbated by high contamination with microorganisms and other contaminants during production, procurement, processing and distribution. to tackle the problem, understanding the production, processing and microbial load of raw milk and measuring its hygiene quality is necessary. objectives: the study was conducted with the objective of assessing milk production, handlings, constraints of milk production and marketing, and its hygiene in urban and peri urban areas of girar jarso district of oromia regional state, ethiopia. materials and methods: a total of 150 respondents were interviewed using pretested questionnaire to collect data on dairy cattle management, milk production, hygienic conditions, milk production constraints and marketing. moreover, 60 milk samples were collected and analyzed for mean aerobic mesophilic bacterial count (ambc), total coliform count (tcc), and spore forming bacterial count (sfbc). results: the major feed resources were communal grazing land, crop residues, grass hay, concentrate feeds and non-conventional feed such as atella. the mean estimated daily milk yield/day/cow was 12.15 ± 0.26 and 2.69 ± 0.04 liters for crossbred and local cows, respectively. average lactation lengths of local and crossbred dairy cows were 6.58 ± 0.22 and 9.19 ± 0.11 months, respectively. shortage of feed, lack of clean water, appropriate utensils and adequate markets during fasting season were the major constraints to dairy production in the study area. the mean ambc, tcc and sfbc for milk samples collected from producers at farm gates were 6.42 ± 0.07, 4.49 ± 0.09 and 2.59 ± 0.05 log10 cfu ml-1, respectively. conclusion: it is concluded that dairy productivity in the study area is low and of poor quality as a result of different constraints and therefore good dairy husbandry and hygienic milk handling practices should be promoted to improve milk productivity and milk quality in the study area. keywords: feed; hygienic handling; microbial quality; milk yield; production constraints. 1. introduction dairy production is an important component of livestock farming in ethiopia (azage et al., 2013). ethiopia is endowed with diverse topographic and climatic conditions favorable for dairy production that support the use of improved, high milk yielding dairy breeds, and offer relatively disease-free environments for dairy production (berhanu, 2012). cattle milk constitutes the larger proportion of the milk produced nationally (83%) (pongruru and nagalla, 2016). however, this potential has been hampered by different challenges such as lack of improved breeds, poor performance of local breeds, and shortage of feed in terms of quality and quantity (pongruru and nagalla, 2016). microorganisms may contaminate milk at various stages including production, procurement, processing and distributions. there is a steady challenge to those involved in milk production to prevent or minimize the entry and subsequent growth of microorganisms in milk (o'connor, 1994). therefore, an understanding of the microbial load of raw milk is important to measure its hygienic quality as high microbial load and presence of harmful pathogenic microorganisms in the milk samples are evidences of unhygienic milk production practices (abrahamsen et al., 2007). the intention of flourishing quality control is not routinely employed at individual farm level, and there is scarcity of data pertaining to the level of spoilage microorganisms and pathogens in commercially available raw cow’s milk. there is a steady challenge to those involved in milk production to prevent or minimize the entry and subsequent growth of microorganisms in milk (o'connor, 1994). teshome et al. (2014) reported an average total coliform count (tcc) of 4.99 ± 0.081log cfu ml-1 for milk marketed in shashemene town. similarly, amistu et al. (2015) also reported 5.42 ± 1.735 to 5.78 ± 0.985 log 10 cfu ml-1 in alemnesh et al. east african journal of sciences volume 14 (2) 151-162 152 special zone of oromia and asaminew et al. (2011) 4.84 log10 cfu ml-1 for milk samples collected from bahir dar milk shed. according to quality and standards authority of ethiopia (ethiopian standards, 2008), tcc of good quality raw milk should not exceed 3 log10 cfu ml-1. the presence of high tcc in milk indicates unsanitary conditions of milk production, processing and storage. there was no formal quality control system in place to monitor and control the quality of milk produced and sold in the girar jarso district. therefore, studying the production practice, quality of cow milk along the milk market chain is important. therefore, the objective of this study was to assess milk production and handling practices, marketing system, production constraints and hygienic quality of raw cow milk along the milk market chain in urban and peri-urban areas of girar jarso district of oromia regional state, ethiopia. 2. materials and methods 2.1. description of the study area the study was conducted in urban and peri urban areas of girar jarso district which is one of the thirteen districts of north shewa zone of oromia regional state, ethiopia. the district is geographically located at 09°45’121’’n latitude and 038°46’728’’e longitude and at an altitude of 2,677 meters above sea level. the district is located at a distance of about 112 km from addis ababa. the mean maximum and minimum temperatures of the area are 22.13 °c and 10.26 °c, respectively and average long-term annual rainfall is 1000 mm (nsmolf, 2016, unpublished). 2.2. design of the study this study had two parts (survey and laboratory experiment). for this study, urban (fitche town) and peri-urban (rural kebeles adjacent to fitche town) of girar jarso district were purposively selected based on their milk production and marketing potential. 2.3. survey study a two-stage sampling technique was used for this study. in the first stage, urban and peri urban areas of the district were selected purposively based on milk production potential and participation in marketing. in the second stage, two kebeles from urban and two kebeles from peri-urban areas of the district were randomly selected. the list of all milk producers was obtained from agriculture and rural development office of the district. then the respondents were selected proportionally using random sampling techniques. in addition, 30 milk collectors (15 from urban and 15 from peri-urban areas) were selected to assess milk hygiene across the milk market chain. 2.4. milk sampling techniques a total of 60 samples of raw cow milk (250 ml) were randomly collected based on the lottery method from the previously surveyed dairy farmers at farm gate and milk collection centers during january to march 2016. morning milk was taken from the containers of each of the producer and bulk milk samples were collected from collection centers. the cow milk samples were collected aseptically using sterile bottles and immediately kept in an ice box and transported to dairy technology and microbiology laboratory of holetta agricultural research center for analysis. the milk samples were kept in a refrigerator at 4 °c upon arrival. the samples were analyzed within 24 hours as described by american public health association (apha, 1992) and all laboratory analyses were conducted in duplicates. 2.5. microbiological analysis the microbiological analysis was done through enumeration of major microorganisms namely total aerobic mesophilic bacterial count (ambc), total coliform count (cc), and spore-forming bacterial count (sfbc). to determine ambc, 1 ml milk sample was diluted in 9 ml sterile peptone water (oxoid, cm0009) and serial dilutions were made in sterile peptone water diluents until the expected level of 30300 count was obtained. one of the milk samples from a chosen dilution was placed on the sterile plate. then, plate count agar media (oxoid, cm0325) of 15−20 ml was poured on to the plate and thoroughly mixed with the sample and allowed to solidify for 15 minutes. then the plates were incubated for 48 ± 2 hours at 35 °c in an inverted position. finally, colonies were counted manually (fda, 2003). total coliform count was determined using sterile violet red bile agar (vrba) (oxoid, cm0107). one ml of raw milk sample was added into a sterile test tube containing 9 ml of sterile peptone water (oxoid, cm0009). after thoroughly mixing, the sample was serially diluted up to 10-9 and duplicate samples (each with 1 ml) were pour plated using sterile 15−20 ml vrba. after gently mixing, the resulting plates were allowed to solidify and then incubated at 32 ± 1 oc for 24 hours (murphy, 1996). following incubation, typical dark red or purplish red or pink colonies appearing on the plates, measuring 0.5 mm or more in diameter on un-crowded plates and with bile precipitation around them were counted as coliforms (fda, 2003). to determine sfbc, milk samples were first heat treated in a water bath (chifton, uk) at 80 oc for 10 minutes. appropriate dilutions of the milk samples (1 ml) were plated on duplicate solid plate count agar (oxoid, cm0325) media. then, colonies were counted after 3 days of incubation at 30 oc (roberts and greenwood, 2003). alemnesh et al. ‘producing, processing, marketing and hygiene of cow milk 153 2.6. data analysis the survey data were analyzed using descriptive statistics (mean and percentage) of spss (statistical package for social sciences) software, version 20 (spss, 2011). microbiological data were subjected to analysis of variance (anova), sas procedure, version 9.0 (sas, 2009). tukey's studentized range (hsd) test was employed to detect mean differences among sample sources. the numbers of microorganisms (colony forming units) per milliliter of milk samples were expressed using the following mathematical formula (fda, 2003): where, n = number of colony forming units per milliliter of milk ∑c = sum of all colonies counted on plates n1 = number of plates in the first dilution counted n2 = number of plates in the second dilution counted d = dilution factor of lowest dilution used microbial count data were first transformed to logarithmic values (log10) before statistical analysis. the log10 transformed values were analyzed using the general linear model (glm) procedure of analysis of sas software. yij = µ + li+ sj + eij; where, yij = the dependent variables; µ =overall mean; li = location effect (periurban and urban); sj = collection sites (farm gate and collection center) and eij = random error. 3. results and discussion 3.1. household and farming practices in the study area the majority of the respondents (80%) in the study area were married and male-headed households (table 1). the educational levels of household heads varied between urban and peri-urban areas. about 60% of the household heads in urban areas completed high school education and above, whereas the majority of the household heads (56.7%) in peri-urban areas never went to school. low level of education may have a direct impact on milk production, quality and safety of milk and milk products. education is perceived as one of the prerequisites for the development of market oriented dairy farming and understanding determinants of market channel choices among smallholder dairy farmers (zewdie, 2010). table 1. marital and educational status and farming system of respondents in the study area. variable category urban (n = 60) peri urban (n = 60) overall mean (n = 120) n % n % n % marital status single 7 11.7 1 1.7 8 6.7 married 47 78.3 50 83.3 97 80.8 divorced 5 8.3 8 13.3 13 10.8 widowed 1 1.7 1 1.7 2 1.7 educational status illiterate 12 20.0 34 56.7 46 38.3 read and write 3 5.0 12 20.0 15 12.5 elementary school 0 0 4 6.7 4 3.3 junior school 9 15.0 5 8.3 14 11.7 high school 20 33.3 3 5.0 23 19.2 above high school 16 26.7 2 3.3 18 15.0 farming system livestock only 51 85.0 6 10.0 57 47.5 mixed crop-livestock 9 15.0 54 90.0 63 52.5 note: n = number of respondents. mixed crop-livestock farming system was found to be the major practiced farming system as reported by 90% of the respondents in peri-urban area of the study district (table 1). on the contrary, intensive livestock rearing was the sole farming activity in urban areas, which could be attributed to shortage of land. among the livestock species, cattle are the most important component of the mixed crop-livestock farming system. 3.2. dairy cattle management 3.2.1. feed resource and feeding communal grazing land (64%), crop residues (of barley, teff, wheat and oat straw) (90.8%), grass hay (100%), concentrate feeds (64%) and non-conventional feed (atella) were the major feed resources of dairy cattle in the study area (figure 1). in line with this result, kibru et al. (2015) reported that communal gazing, private grazing and stall feeding were major feeding system in aleta chuko district, southern ethiopia. about 82% of dairy producers in urban area of the district were using purchased concentrate feed as supplement. however, only 47% of the respondents were using purchased supplement feeds in the periurban areas. hay making was the most commonly used means of feed preservation technique in the study area. this was used to mitigate livestock feed shortage during dry alemnesh et al. east african journal of sciences volume 14 (2) 151-162 154 periods of the year and to avoid wastage of feed in times of surplus production during rainy season. in urban areas, grazing land was hardly available except in the backyards and some open communal fields. as a result, the majority of the cattle are kept indoor and fed on purchased hay, crop residues, concentrate and nonconventional feeds (figure 1). figure 1. the major feed resources available in the study area (%). 3.2.2. dairy cattle breeding about 38% of the respondents were used artificial insemination (ai) to breed dairy cows. however, nearly 24% and 20% of the respondents depended on natural mating system using genetically improved bulls and combination of both methods, respectively (table 2). in the absence of ai and improved bull services, some of the farmers were compelled to use (17.2%) local bulls. both ai and veterinary services were delivered by the district livestock agency in both urban and peri urban areas. the ai service was delivered at the cost of 12.00 birr per service and respondents reported that the price was affordable. similarly, a study conducted by kibru et al. (2015) indicated that the majority of the farmers (91%) practiced natural mating system using local bulls available in the area while some of the farmers used both natural and artificial mating system (7%) and only 2% of them used ai in aleta chuko district of southern ethiopia. the present finding agreed with the findings of zewdie (2010) who reported that ai, crossbred and local bulls were the most commonly used methods to breed dairy cows in the central highlands of ethiopia. table 2. breeding system used and available services in the study areas. variables urban (n = 60) peri urban (n = 60) overall mean (n = 120) n % n % n % breeding system ai 33 55 13 21.7 46 38.3 local breed bull 2 3.3 19 31.7 21 17.6 crossbred bull 13 21.7 16 26.6 29 24.1 ai and crossbred bull 12 20 12 20 24 20 available breeding service providers government (ai) 39 65 14 23.3 53 44.1 own bull 0 0 17 28.3 17 14.1 neighbors’ bull 21 35 29 48.4 50 41.8 note: ai = artificial insemination and n = number of respondents. 3.3. family labor division for dairy production members of the households have a range of responsibilities for different dairy farm operations. milking, cleaning of milk containers and barns, animal health management, milk processing and marketing, heat detection and feeding of dairy animals was the major dairy farm activities identified. wives were highly engaged in milking and cleaning of milk containers and barns while husbands were mainly responsible for marketing of milk, feeding, heat detection and animal health management (table 3) in the urban area of the alemnesh et al. ‘producing, processing, marketing and hygiene of cow milk 155 district. children assist in herding activities after and before school times. in the peri-urban area of the district, husbands were most often involved in feeding, watering, health management, milking cows and milk marketing. money earned from sale of milk was exclusively controlled by the husband. kibru et al. (2015) reported that milking, milk processing, barn cleaning and sale of dairy products were mainly performed by wives while live animal marketing and stall feeding were performed by husband in aleta chuko district, southern ethiopia. table 3. family labor division for milk production related activities in the study area. activities location responsibility sharing among family members (%) men women children hired labor feeding and watering of dairy animals urban 8.3 31.7 33.3 26.7 peri urban 28.3 8.4 53.3 10.0 overall mean 18.4 20.0 43.3 18.3 barn cleaning urban 0.0 45.0 36.7 18.3 peri urban 1.7 66.7 20.0 11.6 overall mean 0.9 55.8 28.3 15.0 cleaning of milk container urban 15.0 38.3 25.0 21.7 peri urban 0.0 71.7 21.7 6.6 overall mean 7.5 55.0 23.4 14.1 milking of cow urban 20.0 38.4 8.3 33.3 peri urban 6.7 70.0 5.0 18.3 overall mean 13.4 54.2 6.6 25.8 milk marketing urban 41.7 15.0 40.0 3.3 peri urban 40.0 16.6 36.7 6.7 overall mean 40.9 15.8 38.4 4.9 3.4. daily milk yield and lactation length the overall average number of lactating crossbred and local breed cows owned per household in the study area were 1.92 ± 0.12 and 1.86 ± 0.15, respectively (table 4). the number of lactating crossbred cows varied significantly (p < 0.05) between urban and peri urban areas of the study district. the difference could be attributed to relatively better access to ai service and market opportunities of the urban farmers. the mean estimated daily milk yield/liter/cow obtained from crossbred cows (12.15 ± 0.26) was four times higher than that of the local cows (2.69 ± 0.04). the current report on milk yield of local cows was slightly higher than the earlier report by asaminew et al. (2011) (average of 2 liter/day/cow) and zewdu (2004) (1.8 liters/day/cow) in the first and second lactations in north gonder zone. the overall average lactation length of local and crossbred cows was 6.58 ± 0.22 and 9.19 ± 0.11 months, respectively. the average lactation length of the local cows and crossbred cows observed in this study is only slightly shorter than that reported by debir (2016) in sidama zone, southern ethiopian which were 7.38 ± 10 and 9.79 ± 11 months for local and crossbred cows, respectively. table 4. daily milk yield and lactation length of crossbred and local cows in the study area. variable urban peri-urban overall mean sl n mean± se n mean± se n mean± se number of lactating cows local breed 6 1.16 ± 0.66 37 1.973 ± 0.17 43 1.86 ± 0.15 ns crossbred 59 2.12 ± 0.85a 41 1.63 ± 0.12b 100 1.92 ± 0 .12 * milk yield of cows (liters/day) local breed 6 2.83 ± 0.16 37 2.66 ± 0.20 43 2.69 ± 0.04 ns crossbred 59 13.14 ± 0.34a 41 11.52 ± 0.35b 100 12.15 ± 0.26 ** lactation length (months) local breed 6 6.14 ± 0.26a 37 6.66 ± 0.11b 43 6.58 ± 0.22 * crossbred 59 9.28 ± 0.13a 41 9.04 ± 0.21b 100 9.19 ± 0.11 * note: n = number of respondents. means with different superscripts in the same rows for the same parameter are significantly different at p < 0.05; ns = non-significant; sl = significance level. alemnesh et al. east african journal of sciences volume 14 (2) 151-162 156 according to the report of nsmolf (2016), the total numbers of households using local cows for milk production were about 13,566 with about 2998 households using crossbred dairy cows. a total of 34,638,240 and 23,160,480 liters of milk were produced per annum from crossbred and local cows, respectively. high proportion of households in the district (80%) is engaged in selling raw milk. 3.5. milk hygienic practices 3.5.1. dairy cattle housing almost all of the respondents (99.2%) had separate barn for dairy cattle. most of the cattle houses had roofs made of corrugated iron sheet. some of the households also used crop residue and grasses for thatching roofs (table 5). table 5. daily milk yield and lactation length of crossbred and local cows in the study area. variable urban (n = 60) peri-urban (n = 60) overall mean (n = 120) n % n % n % house type separate house 60 100.0 59 98.3 119 99.2 inside family house 0 0.0 1 1.7 1 0.8 floor material concrete/cement 37 61.7 3 5.0 40 33.4 mud/earthen 0 0.0 20 33.4 20 16.6 stone 23 38.3 37 61.7 60 50.0 type of roof tin/corrugated iron 52 86.7 27 45.0 79 65.8 thatched 8 13.3 23 55.0 41 34.2 note: n = number of respondents. in the urban area, dairy producers built the floor with concrete and stone whereas 95% of the respondents in peri urban area used stone and earthen floor as bedding material. in contrast to this finding, abebe et al. (2012), berhanu (2012) and kibru et al. (2015) reported that cattle share the same house with the family member during the night time in the southern ethiopia. asaminew (2007) also found that some of the households keep cattle in the same room with family members at bahir dar zuria and macha districts. in line with the findings of this study, mustefa (2012) reported for sululta and welmera districts that about 94% of the dairy herd owners used earthen and stone floors. 3.5.2. dairy animal health the major dairy cattle diseases reported in the study area were anthrax (abba sangaa), foot and mouth disease (fmd) (manse), pasteurollosis (gororsiisaa), blackleg (abba gorbaa), mastitis (muchaa dhiitessaa) and metabolic disorder due to imbalance feeding rations (kirkirsiisaa). most of dairy herd owners (93%) encountered cow udder infection. table 6. udder health problems of dairy cattle and treatments practiced in the study area. variable urban (n = 60) peri-urban (n = 60) overall mean (n =120) n % n % n % encounter udder problem yes 16 26.7 14 23.3 30 25.0 no 44 73.3 46 76.7 90 75.0 milk animals with udder problem yes 16 100.0 11 84.6 27 93.1 no 0 0.0 3 15.4 3 6.9 milk from infected udder dispose 11 68.7 3 27.3 14 51.8 use as animal feed 5 31.3 8 72.3 13 48.1 udder disease treatment veterinary treatment 15 93.8 12 92.3 27 93.1 veterinary and traditional treatment 1 6.2 2 7.7 3 6.9 note: n = number of respondents. as a result, milk obtained from infected udders was either discarded (52.8%) or fed to animals (48%) (table 6). in agreement with the current finding, zewdie (2010) reported occurrence of anthrax, fmd, blackleg and mastitis as major diseases in the central highlands and central rift valley of ethiopia. the same author also stated that these diseases usually occurred during the short rainy season (march to may) when animals are in poor body condition due to inadequate feed availability in the preceding dry period. about 93% of alemnesh et al. ‘producing, processing, marketing and hygiene of cow milk 157 dairy herd owners reported udder infection but they had access to veterinary services for udder infection from the nearby government veterinary clinics. milk produced from infected udders of milking cows were either discarded (52.8%) or fed to animals (48%). 3.5.3. milking and milk hygienic practice in the study area, milking was practiced twice a day, in the morning and the evening. about 87.5% of the respondents used a wide-necked plastic vessel for milking whereas only 12.5% of the respondents used an aluminum milking can (table 7). similar studies by teshome et al. (2014) and teklemichael (2012) reported that 84.62% of the surveyed small-scale milk producer in shashemane town and 75% of the surveyed farmers in dire dawa town, respectively used plastic utensils. this might be due to the fact that aluminum made vessels are very expensive, not affordable and are hardly available for most the farmers in the local markets. table 7. milk hygiene practices during milking in the study area. variable urban (n = 60) peri-urban (n = 60) overall mean (n = 120) n % n % n % utensil used for milking wide necked-aluminum can 10 16.6 5 8.3 15 12.5 wide-necked plastic can 50 83.4 55 91.7 105 87.5 cleaning cow’s shed before milking yes 28 46.7 23 38.3 51 42.5 no 32 53.3 37 61.7 69 57.5 wash hand before milking yes 59 98.3 55 91.7 114 95.0 no 1 1.7 5 8.3 6 5.0 wash udder before milking yes 34 56.7 18 30.0 52 43.3 no 26 43.3 42 70.0 68 56.0 use of towel while cleaning udder individual towel 10 16.7 4 6.6 14 11.7 collective towel 17 28.3 5 8.3 22 18.3 not at all 33 55.0 51 85.0 84 70.0 note: n = number of respondents. milking was usually done under poor hygienic conditions where milking rooms were contaminated with cow dung and urine. more than half of the sample households (57.5%) did not clean barn before milking. the influence of dirty cows on total bacteria counts depended on the extent of soiling of teat surface and cleaning procedures, followed immediately before milking (teshome et al., 2015). about 43% of the respondents washed udder of milking cows before milking; however, 70% of these respondents did not use towel to dry up the udder after washing. only 22% of the respondents used common towel to dry up udder after washing. haile et al. (2012) and amistu et al. (2015) also reported that 70−82.5% of smallholder farmers in ethiopia did not practice drying up of udders using individual towel. the results of this study are consistent with the findings of teshome et al. (2015) who reported that 71.79% of the household milk producers washed the teats and udder of the cows before milking, but without using detergents for cleaning udder and teats. 3.6. milk handling practices at collection center milk collection in the study area usually takes place in the morning time for both evening and morning milk. milk was usually sold only in the morning times and hence milk producers store the evening milk in cold water to keep milk temperature lower until the next morning to reduce microbial multiplication. about 86.7% of milk was directly collected from dairy producer, while 13.3% of milk collectors buy milk from milk venders. all dairy farmers deliver milk to milk collection center by themselves (table 8). the majority of milk collectors in the study area practiced milk quality test (table 8). the common quality tests in the study areas were lactometer reading and alcohol test. however, 6.6% of milk vendors did not apply milk quality test. the major dairy processing plants (96.7) such as lame dairy plc (shola milk enterprise), mb plc (family milk), sebeta agroindustry (mama dairy) and elemtu integrated milk industry were the formal customers that buy milk from those private milk collectors in the study area. hotels and restaurants in fitche town were also customers of the milk collectors. the equipment used to store and transport milk at collection centers was plastic container (80%) and only 20% of the collectors used stainless steel. alemnesh et al. east african journal of sciences volume 14 (2) 151-162 158 table 8. milk handling practices at collection centers of the study area. variable urban (n = 15) peri-urban (n = 15) overall (n = 30) n % n % n % source of milk farmers 12 80.0 14 93.3 26 86.7 milk vender 3 20.0 1 6.7 4 13.3 mode of delivery farmer deliver the milk 15 100.0 15 100.0 30 100.0 milk quality test methods upon delivery organoleptic test 42 6.7 74 6.7 11 36.7 lactometer and alcohol test 11 73.3 6 40.0 17 56.7 no test 0 0.0 2 13.3 2 6.6 type of costumer milk processing plant 14 93.3 15 100.0 29 96.7 hotel and restaurant 1 6.7 0 0 1 3.3 milk transportation utensils stainless steel 5 33.3 1 6.7 6 20.0 plastic water bottles 10 66.7 14 93.3 24 80.0 milk cooling facility yes 3 20.0 0 0 3 10.0 no 12 80.0 15 100.0 27 90.0 note: n = number of respondents. 3.7. milk marketing out of the total milk produced per day, the biggest share was supplied to the market. producers also processed milk into butter and cottage cheese (table 9). the total milk (tm) produced per day per household was significantly (p < 0.05) higher for urban (24.63 liters) than that of the peri urban (16.86 liters) households. all dairy producers who sell milk in the study area entered contractual agreements with milk collectors to deliver milk on daily bases and to collect milk money every fortnight. table 9. quantity of milk produced, processed, consumed and marketed in the study area. variable urban peri urban over all mean mean ± se mean ± se mean ± se tm produced/hh/day (liters) 24.63 ± 1.67a 16.86 ± 1.32b 20.75 ± 1.19 tm processed hh/day (liters) 2.33 ± 0.22 1.26 ± 0.19 1.80 ± 0.15 tm consumed hh/day (liters) 1.72 ± 0.10 0.97 ± 0.09 1.35 ± 0.77 tm sold/hh/day (liter) 20.57 ± 1.51a 14.77 ± 1.19b 17.67 ± 0.99 time to arrive at market place (in min) 12.15 ± 1.07b 20.61 ± 1.68a 16.38 ± 1.6 note: tm = total milk and hh = house hold. means with different superscripts in the same rows are significantly different (p <0.05). private milk collectors and cooperatives/union buy milk from the producers on credit basis. establishment of milk groups and milk-collection centers gave dairy farmers a broader choice of milk marketing instead of being dependent on local traders and neighborhood buyers. thus, one entry point for intervention to improve the dairy sector could be the formation of new dairy cooperatives as well as strengthening the existing dairy cooperatives (birhanu, 2013). 3.8. constraint of milk production, quality and marketing the major constraints affecting dairy production in the study area were shortage of feed, lack of land, lack of productive dairy breeds, lack of clean water and presence of poor animal health services (table 10). the current finding was in line with the result of tsegaye et al. (2015) who reported feed shortage, animal health as well as water and labor scarcity problems being the major challenges which affect dairy cattle production and productivity in selected district of sidama zone, southern ethiopia. moreover, limited awareness on hygienic handling, lack of appropriate materials used for milking and milk handling, shortage of capital and hygiene of the milker were found to be the other important constraint to the dairy sector. with regard to market related problems, majority of the respondents reported the absence of adequate milk markets during fasting seasons, high feed prices, and low milk and milk product prices. on the other hand, price regulatory mechanisms were not in place to make such important food item easily available with an affordable price to the large segment of the consumers. alemnesh et al. ‘producing, processing, marketing and hygiene of cow milk 159 table 10. milk production, quality and marketing constraint in the study area. production constraints 1st 2nd 3rd index rank poor quality and quantity feed 80 38 2 0.45 1st lack of land 37 63 0 0.34 2nd lack of productive dairy breeds 0 0 61 0.09 3rd lack of clean water 0 20 16 0.08 4th poor animal health 0 20 8 0.04 5th milk and milk product quality related constraints 1st 2nd 3rd index rank limited awareness on hygienic milk handling 56 55 0 0.37 1st lack of appropriate utensils for milking and milk handling 46 49 9 0.33 2nd shortage of capital 16 34 8 0.17 3rd poor hygiene of the milker 6 23 32 0.13 4th marketing related constraints 1st 2nd 3rd index rank lack of adequate markets during fasting season 62 16 37 0.39 1st increased feed prices 35 59 13 0.36 2nd low price of milk and milk products 23 26 11 0.20 3rd discarding of milk delivered to milk collector 0 8 19 0.05 4th note: index = the sum of (3 times first order + 2 times second order +1 times third order) for individual variables divided by the sum of (3 times first order + 2 times second order +1 times third order) for all variable. 3.9. the microbial quality of raw cow milk in the study area the mean value of aerobic mesophilic bacterial count (ambc) of raw milk samples collected from producers (6.42 ± 0.07) was significantly (p <0.05) lower than that of the milk collectors (7.49 ± 0.10) (table 11). however, significantly (p <0.05) lower bacterial counts of raw milk were observed in both sampling sources of urban areas of the district. the differences in the overall mean of bacterial counts observed in the study area might be attributed to the time elapsed after milking which is longer for collection centers. similar values of ambc 7.28 log10 cfu ml-1 was report by haile et al. (2012) for milk samples collected from different farm sizes in hawassa, southern ethiopia. solomon et al. (2013) also reported 7.08 log10 cfu ml-1 for raw milk samples obtained from the selected largescale dairy farms in debre-zeit town. table 11. bacterial counts of raw cow milk produced and marketed in study area. parameters milk sampling sources location overall mean urban peri-urban ambc farm gate 6.22 ± 0.10c 6.62 ± 0.13b 6.42 ± 0.07 collection center 6.99 ± 0.15b 7.99 ± 0.15a 7.49 ± 0.10 tcc farm gate 3.87 ± 0.13d 5.10 ± 0.13c 4.49 ± 0.09 collection center 6.96 ± 0.18 b 7.13 ± 0.18 a 7.05 ± 0.10 sfbc farm gate 2.42 ± 0.74d 2.77 ± 0.10c 2.95 ± 0.05 collection center 3.27 ± 0.10b 4.13 ± 0.10a 3.7 ± 0.07 note: ambc = aerobic mesophilic bacteria count; tcc= total coliform count and sfbc = spore forming bacteria count. means in all columns and rows bearing with different superscripts letters for the same parameter are significantly different from each other (p <0.05). however, the results obtained in this study are lower than the findings of haile et al. (2012) and teklemichael (2012) who reported a total bacterial count of 9−10 log10 cfu ml-1. according to quality and standards authority of ethiopian (ethiopian standards, 2009), good quality milk should not contain a total bacterial count of more than 5 log10 cfu ml-1 which indicated that the milk produced and marketed in the study area did not meet the quality standards set by the same authority. the majority of the households in the study area reported the use of plastic containers for milking, transporting and storage. but these types of containers are not easy to clean with locally available cleaning methods and hence the milk residue may favor microbial multiplication that ultimately leads to having poor quality milk. the overall mean total coliform count (tcc) observed from farm gate (4.49 ± 0.09) is lower than the result of teshome et al. (2014) who reported an average tcc of 4.99 ± 0.081log10 cfu ml-1 for milk marketed in shashemene town. however, the current study showed higher tcc values than the finding of abebe et al. (2012) who report 4.18 ± 0.01 log10 cfu ml-1 for raw milk samples in the ezha districts of the gurage zone. in the current study, the tcc of raw milk sampled from collection centers (7.05 ± 0.10) were significantly (p < 0.001) higher than that of milk samples taken from the farm gate. according to es (2008), the tcc alemnesh et al. east african journal of sciences volume 14 (2) 151-162 160 of good quality raw milk should not exceed 3 log10 cfu ml-1. the presence of high tcc in milk indicates unsanitary conditions of milk production, processing and storage. moreover, presence of large number of tcc in dairy products is an indicator of potential hazard to consumer’s health due to possible presence of other enteric pathogens (godefay and molla, 2000). the spore forming bacteria count (sfbc) found from the samples of peri urban producers and collectors was significantly (p < 0.0001) higher than that of milk samples from urban producers and collector (table 11). this result is lower than the report of teshome et al. (2014) who indicated 4.703 ± 0.069 log10 cfu ml-1 in shashemene town. 4. conclusion the results of the current study have demonstrated that the major feed sources for cattle in the study area were a combination of grazing, grass hay, crop residues, concentrate and non-conventional feed resources like atella and bean hull. the overall average numbers of lactating local and crossbred cows per household in the study area were 1.86 ± 0.15 and 1.75 ± 0.16, respectively. about 99.2% of the farmers used separate house type barn for cows of which about 65.8% used corrugated iron sheet covered barns and the rest used grass thatched roof barns. mean aerobic bacterial count (ambc), coliform count (cc) and spore forming bacterial count (sfbc) for milk samples collected from milk collection center were significantly higher (p <0.05) than milk samples obtained from farm gates. generally, the overall microbial count increased during milking at on-farm to collection centers, reflecting poor hygiene at milking, milk handling and transportation. this is mainly due to poor hygienic condition of the feeding system, milking environment, poor udder and teats cleaning practices, failure to use separate towel for each cow and the poor personal hygiene of the milkers. therefore, awareness should be created on the importance of adequate udder preparation, hygienic milking environment, and use of appropriate milk equipment to produce and supply wholesome milk to the market. moreover, milk collection centers should be equipped with cold chains, the necessary dairy equipment and quality water supply to minimize milk contamination. 5. acknowledgements the authors would like to acknowledge dilla university for financial support and holleta agricultural research center for technical support and laboratory facilities to conduct microbiological analysis. we also give special thanks to girar jarso agriculture and rural development office workers and the community for their support during data collection. 6. references abebe, b., zelalem, y. and ajebu, n. 2012. hygienic and microbial quality of raw whole cow’s milk produced in ezha district of the gurage zone, southern ethiopia. journal of agricultural biotechnology and sustainable development, 5(6): 91−98. abrahamsen, r.k., borg, g.i., harstad, o.m., haug a. and wetlessen, a. 2007. milk quality-future approach from a researcher’s point of view. norwegian food research institute (matforsk), osloveien, norway. journal animal and feed science 16(1): 209−226. amistu, k., degefa, t. and melese, a. 2015. assessment of raw milk microbial quality at different critical points of oromia to milk retail centers in addis ababa. food science and quality management, 38: 1−9. apha (american public health association). 1992. standard method for the examination of dairy products. 16th edition. apha, washington, dc, u.s.a. pp. 213−223. asaminew, t. 2007. production, handling, traditional processing practices and quality of milk in bahr dar milk shed area, ethiopia. msc thesis, haramaya university, ethiopia. asaminew, t. and eyassu, s. 2011. microbial quality of raw cow’s milk collected from farmers and dairy cooperatives in bahir dar zuria and mecha district, ethiopia. agriculture and biology journal of north america, 2(1): 29–33. azage, t., berhanu, g., dirk, h., berhanu, b. and yoseph, m. 2013. smallholder dairy production and marketing systems in ethiopia: ipms experiences and opportunities for marketoriented development. improving productivity and market success of ethiopian. farmers project working paper 31. ilri, nairobi. berhanu, k. 2012. market access and value chain analysis of dairy industry in ethiopia: the case of wolaita zone. phd dissertation, alemaya university, ethiopia. birhanu, m. 2013. the impact of market-oriented dairying on the socio-economic position of women farmers in selale areas, oromia national regional state, ethiopia. pp. 157−171. in: prah, m. (ed.). insight into gender equality and power relations in sub-saharan africa. african books collective, uganda. debir, l. 2016. assessment of breeding practice and evaluation of estrus synchronization of dairy cattle in sidama zone, southern ethiopia. msc thesis, hawassa university, ethiopia. ethiopian standards. 2008. unprocessed whole/raw cow milk specification. es: 1st ed., 3460:2008. ethiopian standards. 2009. unprocessed whole/raw cow milk specification. 2nd ed., es: 3460:2009. alemnesh et al. ‘producing, processing, marketing and hygiene of cow milk 161 fda (food and drug administration). 2003. bacteriological analytical manual online. u.s. food and drug administration, center for food safety and applied nutrition. pp. 1–14. godefay, b. and molla, b. 2000. bacteriological quality of raw milk from four dairy farms and milk collection center in and around addis ababa. berl munch tierarztl wochenschr, 113 (7-8): 276−8. haile, w., zelalem, y. and yosef, t. 2012. hygienic practices and microbiological quality of raw milk produced under different farm size in hawassa, southern ethiopia. agricultural research and review. 1(4): 132−142. kibru, b., brihan, t. and teka, f. 2015. characterization of smallholder cattle milk production system in aleta chukko district, southern ethiopia. journal of advanced dairy research, 3: 132. doi:10.4172/2329-888x.1000132. murphy, s.c. 1996. sources and causes of high bacteria count in raw milk: abbreviated review. cornell university, ithaca, n.y. pp1−4. mustefa, a. 2012. value chain and quality of milk in sululta and welmera weredas, oromia special zone surrounding addis ababa, oromia, ethiopia. msc thesis, addis ababa university, ethiopia. o’connor, c.b. 1994. rural dairy technology. ilri training manual no.1. 1995. international livestock research institute, addis ababa, ethiopia. pp. 133. pongruru, c.s. and nagalla, v. 2016. agribusiness review on milk and milk products in ethiopia. international journal of economics and business management, 2(1): 143−152. roberts, d. and greenwood, m. 2003. practical food microbiology. 3rd edition. blackwell publishing ltd, osney mead, oxford ox2 0el, uk. sas (statistical analysis system). 2009. users guide. version 9.2 institute, inc. carry, nc. solomon, m., mulisa, m., yibeltal, m., desalegn, g. and simegnew, k. 2013. bacteriological quality of bovine raw milk at selected dairy farms in debre zeit town, ethiopia. comprehensive journal of food sciences and technology research, 1(1): 1−8. spss (statistical package for social sciences). 2011. statistical packages for social sciences. version 20. spss corporation. teklemichael, t. 2012. quality and safety of raw and pasteurized cow milk produced and marketed in dire dawa town. msc thesis, haramaya university, ethiopia. teshome, g., fekadu, b. and mitiku, e. 2014. handling practices and microbial quality of raw row's milk produced and marketed in shashemene town, southern ethiopia. international journal of agriculture and soil sciences, 2: 153−162 teshome, g., fekadu, b. and mitiku, e. 2015. physical and chemical quality of raw cow's milk produced and marketed in shashemene town, southern ethiopia. journal of food and agricultural science, 5(2): 7−13. tsegay, l., agengew, a. and ashenafi, s. 2015. dairy cattle production at small holder level in sidama zone selected districts, southern ethiopia. food science and quality management. 40(online). available at www.iiste.org. zewdie, w. 2010. livestock production systems in relation with feed availability in the highlands and central rift valley of ethiopia. msc thesis, haramaya university, haramaya, ethiopia. zewdu, w. 2004. indigenous cattle genetic resources, husbandry practices and breeding objectives in north western ethiopia. msc. thesis, haramaya university, ethiopia. alemnesh et al. east african journal of sciences volume 14 (2) 151-162 162 ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15(2): 115-128 licensed under a creative commons *corresponding author: tesfayebecon@gmail.com attribution-noncommercial 4.0 international license. multi-criteria based watershed prioritization for soil and water conservation: the case of gotu watershed, awash river basin, ethiopia tesfaye wasihun abro department of geography and environmental studies, dire dawa university, dire dawa, ethiopia abstract background: in ethiopia, soil and water conservation has often been implemented haphazardly through community mobilization during dry seasons. however, in the process, the question “which part of the watershed should be conserved first considering different criteria and which one should be the last?” is never been answered. objective: this study was undertaken to prioritize sub-watersheds on the basis of myriad of parameters: morphometric, soil loss, socioeconomic and related criteria for soil and water conservation activities in five catchments in gotu watershed, awash river basin, ethiopia. materials and methods: advanced space borne thermal emission and reflection radiometer digital elevation model, revised universal soil loss equation (rusle), socioeconomic and related data like population density, share of cultivated land, economic status, land pressure, potential labor force for conservation, conservation work performance, and share of unirrigated land were used for prioritization exercise. results: it was found that gotu watershed has seven order streams with a mean bifurcation ratio of 2.1; higher stream frequency = 6.4–7.9 streams km–2; low drainage density (0.52–2.85 km km–2) and moderate drainage texture (3.7–5.7); elongated shape (form factor = 0.16–0.23; elongation ratio = 0.45–0.53; circulatory ratio = 0.17–0.24). using rusle model, the soil loss of the study catchments ranged from 0 t ha–1yr–1in the plain area up to 197.2 t ha–1 yr–1 in the steeper, and fragile part of the watershed which made catchment two an area of severe soil erosion. considering socioeconomic parameters, catchment five and catchment two have been shown with low and high status, respectively. therefore, the combined result showed that catchment five that measures about 17.77 km2 out of 160.56 km2 of the total area of the study watershed requires the first priority for soil and water conservation measures. conclusion: it is concluded that catchments with high soil loss may not usually guarantee primary attention for conservation unless the condition of socioeconomics, morphometry of catchments and related parameters simultaneously contribute to the decision-making process of conservation planners. this implies that land conservation planners should reconsider prioritization criteria of resource flows to soil and water conservation initiatives. keywords: morphometric parameter; rusle model; socioeconomics; gis and rs 1. introduction a watershed is an area of land and water bounded by a drainage divide within which the surface runoff collects and flows out of the watershed through a single outlet into a larger river or other water bodies (russo et al., 2008; rahman et al., 2015). a watershed is an ideal unit that enables interactions among various natural resources, humans, and animals as they all make a unique geo-hydrological entity. hence, any disruption caused to a watershed is the disturbance of the whole aspects of socioeconomic development and environmental sustainability (woldeamlak bewket, 2003). in countries like ethiopia, where a major part of the population primarily depends on natural resources for livelihoods, the prevailing form of agricultural land use, and the geomorphology of the country makes them susceptible to watershed resources stress. land degradation in the form of soil erosion (woldeamlak bewket, 2003; temesgen et al., 2017) is a common problem in the highlands of ethiopia. for example, in awash river basin alone, up to 259 mt year– 1 total erosion occurs contributing to high sedimentation (awba, 2017); and the country is losing 2 to 6.75% of agricultural gdp annually from its basins (sonneveld, 2002). these demands conservation and or development of watershed, for sustainable production of food, fodder, and other agriculture and forest resources for immediate and long-term benefits to the farmers, community, and the basin as a whole. however, watershed development requires financial, human, organizational and other resources which may not be achieved at a time especially in larger watersheds (mulatie mekonnen and assefa melesse, 2011) making prioritization imperative. yet, prioritization criteria need to be framed in consideration of the actual reality on the watershed. because a watershed may be higher in soil loss but the socioeconomic condition of the society may be better off. for example, sharma and thakur (2016) found out that micro-watersheds with mailto:tesfayebecon@gmail.com tesfaye east african journal of sciences volume 15 (2): 115-128 116 severe soil loss were prioritized least based on socioeconomic and demographic prioritization criteria for conservation. unfortunately, consideration of these variables in soil and water conservation prioritization is lacking in ethiopia, much emphasis has been given to severity of soil loss as a criterion (ermias teferiet al., 2009; woldeamlak bewket and ermias teferi, 2009; temesgen gashaw et al., 2017) and community mobilization during dry season haphazardly. therefore, this study was intended to prioritize gotu watershed in consideration of relatively many parameters (physical, rusle indices, socio-ecodemographic and related). the study area was selected for multiple reasons. first the area is prone to soil erosion problems due to overgrazing, over-cultivation, over-exploitation of the vegetation cover; and due to expansion of crop land to steep slopes. besides, since resource managers have made significant efforts to conserve the area, it is still better to convey prioritization scientifically. the findings of this study could serve as hands on checklist for conservation planners in making knowledge-based decision or for financial and human resource flow in soil and water conservation programs. 2. material and methods 2.1. study area the study area, gotu watershed, is part of the awash river basin and administratively found in north habru woreda (district), north wollo zone of the amhara national regional state, ethiopia. geographically, it lies between 11°34'44″ and 11°45'4″n latitude, and 39°34'11″ and 39°45'2″e longitude (figure 1). the area is 160.56 km2 wide, covering 9% of habru woreda (1671.83 km2). the present complex topography of the area has been formed by a large-scale tectonic and volcanic activity and covered by cenozoic volcanic rocks (mohr 1971). it is composed of a rugged topography and relatively vast plain areas with elevations ranging between 1364 to 3508 meters above sea level. figure 1. location map of the study area: bottom left—awash basin, top left—ethiopia watersheds right—gotu watershed with catchments and elevation information. according to the traditional agro climatic classification, the study area dominantly lies within dega (2300– 3300masl), weyna dega (1500–2300masl), and kola (1364– 1500masl) zones. based on a data set from five meteorological stations from the year 2000–2017 the mean annual temperature was 24.5 °c; and characterized by bi-modal pattern of rainfall with a mean annual rainfall of 935.7mm for the years from 2007–2017. the major soil types in the study area are vertisols, cambisols, and regosols (amhara design and supervision works enterprise, 2011). the study watershed is inhabited by a total population of 48108 with a density of 299 persons/km2, which is far higher than the average for amhara regional state (108.2 persons km–2) (csa, 2007). agriculture is the main economic activity with mixed crop-livestock production on a subsistence level. 2.2. input data and methodology for the analysis of morphometry of gotu watershed, aster dem 30 meter resolution (http://earthexplorer.usgs.gov/) was used to delineate and generate the value of different parameters like bifurcation ratio (rb), stream frequency (fs), drainage density (dd), drainage texture (dt), elongation ratio (re), circulatory ratio (rc), form factor (ff), compactness coefficient (cc), basin relief (h), relief tesfaye multi-criteria watershed prioritization for soil and water conservation 117 ratio (rh), and ruggedness number (rn). identification of smaller geohydrological units is needed for more efficient and better targeted resource management programs (sharma and thakur, 2016). based on this, gotu watershed has been classified in to five catchments using arcswat in arcgis 10.4 which were coded as: catchment one = ci; catchment two = cii; catchment three = ciii; catchment four = civ and catchment five = cv. then, after creating shape file of watersheds, dem of each catchment was masked and filled the sink; flow accumulation threshold value of 1000 was used and the result stream networks were cross checked with toposheet (1:50,000 scale) of mersa to have approachable results and generated streams of five catchments (figure 4). on the other hand, for soil loss estimation using rusle model, input data like rainfall data (2008–2017) from national meteorological agency, soil data, aster dem 30 m, and lulc were used. erdas 9.2 was used for layer stacking of landsat 8 bands for lulc classification but other rusle indices outputs were generated using arcgis 10.4 software. table 1. parameters and prioritization scheme as adapted from sharma and thakur (2016). morphometric parameter definition/formula priority condition references bifurcation ratio (rb) rb = nu/nu+1 higher the value, more the priority schumm (1956) stream frequency (fs) fs = nu/a higher the value, more the priority horton (1932) drainage density (dd) dd= lu/a higher the value, more the priority horton (1932) drainage texture (dt) dt = nu/p higher the value, more the priority horton (1945) compactness coefficient (cc) cc = 0.2821p/a0.5 higher the value, more the priority horton (1945) form factor (ff) ff=a/lb2 lower the value, more the priority horton (1932) elongation ratio (re) re=2/lb*(a/ π)0.5 lower the value, more the priority (schumm ( 1956) circulatory ratio (rc) rc = 4 * π* a/p2 lower the value, more the priority miller (1953) basin relief (h) he-le higher the value, more the priority hadley and schumm (1961) relief ratio (rh) rh = h/lb higher the value, more the priority schumm (1956) ruggedness no. (rn) rn = h * d higher the value, more the priority melton (1957) soil loss a=r.k.l.s.c. p higher the average annual soil loss risk, more the priority wischmeier and smith (1978) economic demographic parameters* population density (pd) low, medium, high the higher the density, higher the priority badar et al., (2013) average economic status (es) low, medium, high the lower the status, higher the priority badar et al., (2013) cultivated land (cl) calculated from the generated lulc the lower the percentage, higher the priority satellite image analysis (http://earthexplorer.us gs.gov/) unirrigated land (unirr.) very low, moderate, high, very high higher the unirrigated land, more the priority land pressure (lp) low, medium, high higher the pressure, more the priority training received (tr) number of trained farmers the lower the number in relative to other catchment, the higher the priority badar et al., (2013) potential labor force (plf) low, medium, high the lower the productive age group, the higher the priority badar et al., (2013) wsd performance rank (pr) 1st, 2nd, 3rd, 4th, 5th the lower the rank, the more the priority other parameters ground cover low, moderate, high higher the ndvi, lower the priority rouse (1973) sti (flow acc./22.13)0.6 *(sin β/0.0806)1.3 higher the value, more the priority spi (flow acc. + 1)* (tan β) higher the value, more the priority moore et al., (1991), florinsky (2012) twi ln (facc/ tan β) lower the value, more the priority beven and kirkby, (1979), florinsky (2012) note: a = average annual soil loss potential; r = rainfall erosivity; k = soil erodibility; l = slope length; s = slope steepness; c = land cover management factor; p = conservation practices factors; ndvi = normalized difference vegetation index; wsd = watershed; and plwsdd = potential labor force for watershed development. *analyzed on the basis of secondary data from habru woreda agriculture and rural development office and woreda socioeconomic development and finance office (2017). tesfaye east african journal of sciences volume 15 (2): 115-128 118 moreover, socio-eco-demographic data regarding the various parameters like population density, economic status, cultivated land, unirrigated land, participation in watershed conservation, training received related to watershed development, potential labor force, and land pressure for all the catchments of study watershed were collected from the habru woreda agricultural office and personal interviews with natural resource and rural development experts. furthermore, other parameters such as ground cover condition, sediment transport index (sti), stream power index (spi) and topographic wetness index (twi) were also considered for prioritization exercise. das et al. (2012) indicated that criteria for watershed prioritization are subjective in nature. therefore, in this study, the basis for assigning weightage to different themes (morphometric, socio-eco-demographic, and mixedrusle factors) was in consideration of which parameter need more attention in relation to prioritization for soil and water conservation. based on this, soil loss using rusle model has given more weight (5) because human interventions (c and p factors) have more influence on soil loss plus physical indices are also embedded in the model. then, the compound value of all the parameters was generated using the following weighted mean formula. wx− = w1∗x1+w2∗x2+w3∗x3…wnxn w1+w2+w3…wn where, wx– = weighted mean; w1 = weight one; w2 = weight two ….; and x’s = parameters. finally, based on average value of these parameters, catchments having the least rating value were assigned the highest priority; the next value was assigned second priority and so on. figure 2. flow chart of methodology. 3. results and discussion 3.1. morphometric analysis using strahler (1957) system of stream ordering, gotu watershed has seven order main streams, each order streams in each catchment having a varying number of streams (figure 3). the study area has a total of 1127 streams, of which 562 were first order; 278 were second order; 130 were third order; 84 were fourth order; 38 were fifth order; 34 were sixth order; and 1 was seventh order streams with the corresponding stream length (km) of 123.5, 50.4, 30.42, 10.07, 4.68, 4.92 and 5.04, respectively (table 2). tesfaye multi-criteria watershed prioritization for soil and water conservation 119 figure 3. stream orders of gotu sub-watersheds produced from aster dem. the study watershed has an area of 160.56 km2 with 675 total streams with a total stream length of 219.12 km. this means that there are about 7.04 streams in each km2 area and an average of 1.36 km stream length per km2 area. catchment (c) wise, catchment four and catchment two are the highest in terms of stream length with 58.29 km, and 51.35 km, respectively (table 2). the morphometric parameters (table 1) have been used for prioritizing watersheds. the linear parameters such as bifurcation ratio, stream frequency, drainage density, and drainage texture have a direct relationship with soil loss; the higher the value, the more is the soil loss. in contrast, shape parameters such as circularity ratio, elongation ratio, form factor, and compactness coefficient have an inverse relationship with erodibility. the intensity of dissection (expressed as bifurcation ratio) influences the discharge and flooding. in the present study, out of the five catchments, only catchment one has bifurcation ratio (rb) of 3.0 (table 2) that qualify horton’s (1945) natural drainage characteristics of rb value (3.0 to 5.0). horton (1945) noted that the value of stream frequency depends on the total number of streams and the corresponding basin area. in the present study, stream frequency varies from 6.4 to 7.9 streams per square kilometer. in general, the higher the drainage density, the less the density of vegetation cover (table 3 and figure 6) and the more impermeable soil and rock surface which lets the movement of overland flow of runoff and hence reflecting the presence of enhanced soil erosion. the drainage density varies from 0.52 to 2.85 km km–2 reflecting comparatively high permeable surface and lower soil erosion rate. 3.2. estimating soil loss the soil loss in gotu sub-watershed was estimated using rusle model–an efficient and quite reliable method of predicting soil loss as it considers both the physical and anthropogenic factors which are responsible for causing soil erosion (wischmeier and smith, 1978). catchment wise, a moderate soil loss was observed in three catchments (cv, ciii and civ) while the remaining two catchments experienced a severe soil erosion (figure 5). tesfaye east african journal of sciences volume 15 (2): 115-128 120 table 2. linear aspects of morphometrical parameters. catchment parameter stream order 1st 2nd 3rd 4th 5th 6th 7th 1 no. of streams 134 62 31 34 5 stream length/km 18.8 11.52 1.49 5.75 0.12 ave. length/km 0.99 0.96 0.37 1.15 0.12 basin length (km) 11.24 mean rb 3 2 no. of streams 133 68 33 26 stream length/km 30.45 7.69 11.15 2.06 ave. length/km 1.12 0.64 0.85 1.03 basin length (km) 13.02 mean rb 1.7 3 no. of streams 125 65 32 15 13 1 stream length/km 13.61 2.8 0.13 0.012 4.56 0.35 ave. length/km 1.04 0.93 0.07 0.012 0.41 basin length (km) 10.49 mean rb 1.8 4 no. of streams 105 55 23 9 13 11 stream length/km 32.28 18.54 7.47 4.92 ave. length/km 1.19 1.09 0.93 basin length (km) 13.88 mean rb 1.7 5 no. of streams 65 28 11 7 23 stream length/km 28.41 9.85 10.18 2.25 4.69 ave. length/km 1.05 0.98 0.78 2.25 basin length (km) 14.34 mean rb 2.4 tesfaye multi-criteria watershed prioritization for soil and water conservation 121 figure 4. streams in gotu catchments derived from aster dem. tesfaye east african journal of sciences volume 15 (2): 115-128 122 table 3. morphometric parameters. catchment a (km2) p (km) fs dd dt ff re rc cc h (km) rh rn ci 40.08 46.07 6.6 0.94 5.7 0.23 0.53 0.23 2.05 1.88 0.14 2.41 cii 27.41 42.71 7.9 1.87 5.1 0.21 0.52 0.19 2.30 0.7 0.060 0.96 ciii 40.44 45.69 6.4 0.52 5.6 0.21 0.50 0.24 2.02 2.02 0.145 2.9 civ 34.9 45.88 7.1 1.67 5.4 0.17 0.46 0.20 2.19 2.19 0.063 1.32 cv 17.77 35.44 7.5 2.85 3.7 0.16 0.45 0.17 2.37 0.61 0.05 0.73 note: a = area; p = perimeter; fs = stream frequency; dd = drainage density; dt = drainage texture; ff = form factor; re = elongation ratio; rc = circulatory ratio; cc = constant of channel maintenance; h = basin relief; rh = relief ratio; and rn = ruggedness number. the later may be attributed to the physical relief (average of h, rh and rn is highest) (table 3) which was consistent with previous studies by woldeamlak bewket and ermias teferi (2009); mulatu mekonnen and assefa melese (2011); temesgen et al. (2017); birhan asmame and assefa abegaz (2017), and gezahegn et al. (2018). however, ciii showed higher physical relief but moderate soil loss. this may be due to better land use and land cover conditions (figure 5). figure 5. soil loss computed using rusle model. tesfaye multi-criteria watershed prioritization for soil and water conservation 123 table 4. soil loss (t ha–1year–1) of each catchment. catchment soil loss (t ha–1yr-1) area (km2) ci <3.5 19.0 3.6–22 7.0 22.7–69.9 14.08 cii <10.8 13.6 10.9–64.2 6.0 64.3–197 7.81 ciii <2.09 19.0 2.09–7.25 13.4 7.26–19.07 8.04 civ <2.7 21.8 2.7–10.2 4.6 10.3–32 8.5 cv <0.58 10.1 0.58–2.19 6.2 2.2–7.79 1.4 note: ci = catchment one; cii = catchment two; ciii = catchment three; civ = catchment four; and cv = catchment five. 3.3. socio-economic and demographic analysis the socioeconomic and demographic data (table 5) revealed that catchment four and catchment five were the highest and the lowest in terms of population density and economic status, respectively. the higher population density is attributed to the presence of congested town (girana) largest market center pulling the surrounding population, suitable climate, and much irrigable land and thus the population has relatively better economic status. conversely, the lowest population density and economic status is found in the eastern part of the watershed i.e. catchment five which lies near to afar region in an area of hot temperature and low rainfall amount, low irrigation access, and relatively steep terrain. according to a report of habru woreda agriculture office (2017), potential labor force for working to develop the watershed was identified from all 35 rural kebeles in the woreda, and training was offered to farmers in relation with watershed development activities. based on this, the greater the number of trained farmers in a catchment, the lower the priority for soil and water conservation expecting that the trained farmers may mobilize other farmers for participation in conservation activities. table 5. socioeconomic and demographic data with respect to different catchments. criterion catchment ci cii ciii civ cv population density 224 273 280 296 199 economic status 4th 2nd 3rd 1st 5th potential labor force 1820 3206 3102 3312 1815 cultivated land (%)* 38.9 47.8 30.9 42.7 43.6 unirrigated land low medium high very low very high land pressure high vh low low high number of farmers received training 305 313 281 432 190 wsd conservation performance rank 8 1 12 16 22 note: ci = catchment one; cii = catchment two; ciii = three; civ=catchment four; and cv= catchment five. analyzed on the basis of secondary data from habru woreda agriculture and rural development office and woreda socioeconomic development and finance office (2017). *analyzed from landsat 8 image. thus, the results in table 5 showed that catchment five has lower number of trained farmers (190) relative to other catchments. concerning cultivated land, the analyzed image of landsat 8, the analysis showed that about 64.0161 km2 (39.87%) area of total land is under cultivation in the five catchments of gotu watershed (figure 6). catchment wise, almost half (47.8%) of the total area is under crop cultivation in cii. it observed that crop cultivation is a dominant activity and has a significant share as an economic pursuit in the remaining catchments. the woreda agriculture and rural development office (2017) report revealed that watershed development work performance of each kebele is usually evaluated quarterly by experts using field observations in each tesfaye east african journal of sciences volume 15 (2): 115-128 124 catchment area and by releasing performance ranking. accordingly, population in catchment two and catchment one has a better record in watershed development activities and catchment five with the lowest performance (table 5). catchment two and catchment one are the leading ones in terms of pressure exerted on the land due to the presence of cross over main asphalt road in these catchments. farmers usually sell fuelwood collected from the available bush lands in the highlands to make ends meet. figure 6. land use land cover of gotu catchments derived from landsat 8. 3.4. other parameters sediment transport index value ranged from 1.88 in cv to 5.22 in ciii. the highest value was associated with steep slope and ridges which may contribute to sediment transportation and consequent soil erosion and degradation. the sediment transport index result has relative similarity with the relief parameters i.e. the higher sediment transport index value is found in areas with steep slopes (tables 3 and 6). table 6. other parameters (derived from dem and landsat-8 oli). parameter catchment ci cii ciii civ cv sediment transport index 4.86 2.03 5.22 2.30 1.88 stream power index 31.58 26.78 35.71 14.07 64.91 topographic wetness index 15.53 16.93 15.09 15.68 18.04 ndvi as a proxy for ground cover condition 0.37 0.43 0.38 0.35 0.45 note: ci = catchment one; cii = catchment two; ciii = three; civ = catchment four; and cv = catchment five. similarly, high stream power index values represent areas on the landscape where high slopes and flow accumulations exist and thus areas where flows can concentrate with erosive potential. the higher the power of stream, the greater the probability of vulnerable topsoil washing down and contributing strongly to the land degradation process, and then transporting soil material and sediment to the plain areas. so, in the present study, the western and eastern parts of the watershed (cv = 64.91) have high stream power which may be associated with more inflow of water from the upper areas (increase in the stream orders i.e. seventh order stream is entirely found in cv). this implies that more attention should be given to soil conservation due to high probability of erosion. topographic wetness index, on the other hand, was used to show wetness of an area and related to slope of the area i.e. water tend to accumulate in flat area than steep slope area and hence the more the topographic wetness index, the flatter the slope and hence more flow accumulation and wetness (beven and kirkby, 1979). tesfaye multi-criteria watershed prioritization for soil and water conservation 125 3.5. prioritization of catchments all catchments in gotu watershed have been prioritized by considering the weighted average of different parameters–morphometric, soil loss, socio-ecodemographic and others (table 7). the value of the comprehensive weightage of all the parameters varied from 2.71 (lowest) to 3.3 (highest). out of the five catchments, cv was assigned as high priority while civ as low priority. catchments with high priority indicate the need of soil and water conservation attention to them before other catchments. the least prioritized catchment, i.e., civ has better socio-economic status, and lower aggregate morphometric ranking with medium soil loss priority (table 7) whereas cv– given high priority which was characterized as lower relative soil loss and lower socio-eco-demographic condition. however, in terms of individual parameters, catchments with high priority in soil loss ranked the second least in terms of priority in aggregate morphometric indices. but hlaing et al. (2008) has found sub watersheds with high priority in soil erosion also ranked in the morphometric parameters. table 7. comprehensive ranking of catchments. aspect parameter s weight (w) ranking c i w*c i ci i w*ci i cii i w*ci ii ci v w*ci v c v w*c v morphometric rb 3 1 3 4 12 3 9 4 12 2 6 fs 3 4 12 1 3 5 15 3 9 2 6 dd 3 4 12 2 6 5 15 3 9 1 3 dt 3 1 3 4 12 2 6 3 9 5 15 ff 3 5 15 3 9 3 9 2 6 1 3 re 3 5 15 4 12 3 9 2 6 1 3 rc 3 4 12 2 6 5 15 3 9 1 3 cc 3 2 6 4 12 1 3 3 9 5 15 h 3 4 12 3 9 1 3 2 6 5 15 rh 3 3 9 1 3 4 12 2 6 5 15 rn 3 3 9 1 3 4 12 2 6 5 15 soil soil loss 5 2 10 1 5 4 20 3 15 5 25 socio-ecodemographic pd 4 4 16 3 12 2 8 1 4 5 20 es 4 2 8 4 16 3 12 5 20 1 4 cl 4 2 8 5 20 1 4 3 12 4 16 unirr 4 4 16 3 12 2 8 5 20 1 4 lp 4 2 8 1 4 4 16 4 16 2 8 plf 4 2 8 4 16 3 12 5 20 1 4 wpr 4 4 16 5 20 3 12 2 8 1 4 tr 4 3 12 4 16 2 8 5 20 1 4 others ndvi 4 4 16 2 8 3 12 5 20 1 4 sti 3 2 6 4 12 1 3 3 9 5 15 spi 3 3 9 4 12 2 6 5 15 1 3 twi 3 2 6 4 12 1 3 3 9 5 15 sum 83 247 252 232 275 225 wx 2.9 3.0 2.79 3.3 2.71 rank 3rd 4th 2nd 5th 1st note: pd = population density; es = economic status; cl = cultivated land; unirr = un-irrigated land; lp = land pressure; plf = potential labor force; wpr = watershed conservation activities performance rank; and tr = training received related to conservation. in the present study, it was also observed that catchments with high soil loss, low economic status, high population density, low potential labor force, high unirrigated land, high land pressure, and low watershed conservation performance were prioritized first against catchments with lower soil loss and better socioeconomic condition. this result is consistent with the findings of sharma and thakur (2016). in their finding micro watersheds with high soil loss risk, high population size, low agricultural land, high relief ratio, lower economic status was given high priority for soil and water conservation planning while watersheds with low lying area, less areas under steep slope, and low drainage density were assigned to low priority. similarly, vittala et al. (2008) found out that sub watersheds having population with low economic status were given high priority while sub watersheds with better natural resource base were given prioritized least. the aggregate results of prioritization may have their own limitation and, in some cases, inconsistent results may be observed because of the subjective nature of weight assignment to the parameters. therefore, the author acknowledges that the methodology has inherent tesfaye east african journal of sciences volume 15 (2): 115-128 126 limitations and may result in assignment of erroneous weight to the parameters. again, this study was not able to include other important variables affecting prioritization for soil and water conservation. finally, there may also be some overlapping parameters. 4. conclusion this study has demonstrated that gotu watershed has seven order streams with a mean rb of 2.1; low drainage density (0.52–2.85 km km–2) and moderate drainage texture (3.7–5.7); elongated shape (ff = 0.16–0.23; re = 0.45–0.53) and 74.81% of gotu watershed have a less than 0.145 and 2.9 of relief ratio and ruggedness number, respectively. these proved that the watershed has relatively less dissected terrain features; low and extended flood flow and dominance of low sloped terrain. soil erosion was very severe (64.2–197.2 t ha– 1yr–1) in cii as per rusle model. the results of socioeconomic and demographic characteristics, on the other hand, showed that out of the five catchments of gotu watershed, cv was characterized by low economic status, labor force, watershed work and related training participation which made this catchment feasible for primary conservation. finally, the compound results have revealed that relatively cv having an area of 17.77 km2 (11.06%) of gotu watershed, should get the first priority for soil and water conservation. the results of this study could be useful for watershed planners and managers towards implementing various water and soil conservation measures in the study area. it is deduced that catchments with high soil loss may not usually guarantee primary attention for conservation unless the condition of socioeconomics, morphometry of catchments and related parameters are considered simultaneously and contribute to the decision making process of conservation planners. similar studies should be made to understand the condition of different watersheds in ethiopian highlands versus resource flow for soil and water conservation work. 5. acknowledgments the author thanks the amhara national regional state – bureau of agriculture and rural development, ethiopian metrological agency, and habru woreda agricultural bureau for providing soil, meteorological, and annual report data, respectively. also, the author thanks the united states (usa) geological survey for providing remote sensing data free of charge. 6. references awba (awash basin authority). 2017. awash river basin integrated participatory watershed management strategic and 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(ed.). handbook of applied hydrology. mcgraw hill book company, new york. temesgen gashaw, taffa tulu and mekuria argaw. 2017. erosion risk assessment for prioritization of conservation measures in geleda watershed, blue nile basin, ethiopia. environmental system research, 6(1) https://doi.org/10.1186/s40068016-0078-x. vittala, s.s, govindaiah, s. and gowda, h.h. 2008. prioritization of sub-watersheds for sustainable development and management of natural resources: an integrated approach using remote sensing, gis and socio-economic data. current science, 95(3): 345–354. wischmeier, w.h. and smith, d.d. 1978. predicting rainfall erosion losses–a guide to conservation planning. agricultural handbook, number 537 usda. woldeamlak bewket. 2003. towards integrated watershed management for resource conservation in chemoga watershed, northwestern highlands of ethiopia. tropical resource management papers, no. 44. isbn 906754-708-5. woldeamlak bewket and ermias teferi. 2009. assessment of soil erosion hazard and prioritization for treatment at the watershed level: case study in the chemoga watershed, blue nile basin, ethiopia. land degradation and development, 20(6): 609–622. https://doi.org/10.1186/s40068-016-0078-x https://doi.org/10.1186/s40068-016-0078-x tesfaye east african journal of sciences volume 15 (2): 115-128 128 ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15 (2): 141-154 licensed under a creative commons *corresponding author. yirgamasresha@gmail.com attribution-noncommercial 4.0 international license. genetic diversity of coffee (coffea arabica l.) collections for morpho-agronomic traits in southwestern ethiopia masreshaw yirga 1*, wosene gebreselassie 2, and abush tesfaye 3 1jimma agricultural research center, eiar, p.o. box 192, jimma, ethiopia 2college of agriculture and veterinary medicine, jimma university, p.o. box 307, jimma, ethiopia 3international institutes of tropical agriculture, oyo road, p.m.b. 5320, ibadan, nigeria abstract background: information on the genetic variability of plants on the basis population is important for conservation and utilization of genetic resources. however, information on such genetic diversity is not still yet available at individual level in yayu coffee germplasm, southwestern ethiopia. objective: the study was conducted to estimate the genetic variability among coffee collections with respect to morpho-agronomic traits. materials and methods: sixty-two coffee (coffea arabica l.) collections with two standard check varieties (74110 and 74112) were evaluated using 8 x 8 simple lattice design at metu agricultural research sub center. the experiment was conducted on six-year old coffee trees during the 2018 main cropping seasons. the coffee trees were managed as per the recommendation for coffee production practices. results: cluster analysis was employed using 19 quantitative traits and 64 coffee collections grouped into seven clusters. significant inter cluster-distance was found between most of the paired clusters. the results revealed the chance of developing hybrids by crossing coffee collections from cluster-v and vi followed by cluster-iv and vi. principal component analysis revealed that, the first seven principal components with eigen values exceeding one were responsible for about 74.94 % of the observed variation among the coffee collections. out of the entire variations, the first and the second principal components accounted for more than one-third of the total variation (35.32 %). conclusion: the information and genetic variability obtained in the present study could be used to plan conservation, effective pure line selection, and crossing of coffee germplasm in future coffee improvement programs. keywords: germplasm; cluster; genetic divergence; principal component 1. introduction coffee (coffea arabica l.) belongs to the genus coffea, in the family rubiaceae. coffea arabica is one the most important commercial species in the world market (gray et al., 2013). it is the most widely drunk beverages in the world due to its best cup quality and source of income for million people in coffee growing countries (lashermes et al., 2011; mishra and slater, 2012). ethiopia is the fifth major exporter of arabica coffee in the world next to brazil, vietnam, colombia and indonesia; while it is the highest producer among african country. coffee plays significant role in ethiopian cultural and socio-economic life of the nation. it contributes about 35% of the country’s foreign currency earnings and about 25%, the population directly or indirectly drives their income from coffee value chain (usda, 2020). ethiopia is also the origin and center of genetic diversity for coffee arabica species. there is a high genetic diversity of coffee in the country, which is confirmed by several phenotypic and molecular studies (sylvain, 1958; meyer, 1965; kassahun testate, et al., 2013; mesfin kebede and bayetta belachew, 2005; tadesse benti et al., 2021). the entire genetic diversity of indigenous (wild) arabica is confined mainly in the afromontane rain forest located in the west and east of great rift valley (kassahun et al., 2013). hence, the existence of wide genetic variability is expected to safeguard coffee production from dangers posed by possible biotic and abiotic stresses (tadesse woldemariam, 2003). regardless of the presence of substantial genetic diversity in the crop species, the country is still not yet fully utilizing its coffee genetic resources as expected in terms of improving coffee masreshaw et al. east african journal of sciences volume 15 (2): 141-154 142 productivity and the livelihood of the rural community (paulos and teketay, 2000). consequently the national productivity of coffee per unit area remains very low (0.7 t ha–1) (csa, 2018). major contributing factors for low production are uses of unimproved local landrace, conventional husbandry and processing practices (taye, 2010), and the direct and indirect potential impact of climatic variability (davis et al., 2012). arabica coffee gene pool has threatened by genetic erosion mostly attributed to deforestation of its natural habitat, establishment and expansion of modern plantation with illegal and legal settlements (woldemariam et al., 2002). since 1973, considerable coffee germplasm collections have made to capture the available coffee genetic variability for the purpose of selecting and developing adaptable coffee varieties. hence, about 12,452 indigenous and exotic coffee germplasm were collected and ex-situ conserved at the ethiopian biodiversity institute (ebi) (5731 collections) (taye, 2010) and jimma agricultural research center (6721 collections) field gene banks (tadesse, 2017). however, some germplasm died in their maintenance fields due to climate change and adaptation problem, as they are forced to be grown outside of their original environment. it has been well understood that, varieties belonging to one region adapt differently when grown in another region (bayetta et al., 1993). bearing in mind this fact, the national coffee breeding strategy has currently designed location specific adaptation for local landrace variety development and promotion under diverse coffee growing agro ecologies (fikadu et al., 2008). information on the nature and magnitude of genetic variability present in any crop species is a key resource for developing effective crop improvement program through selection or crossing of different parental lines (dabholkar, 1996). these genetic variations can be enumerated at species, populations and individuals. genetic variability is genetic differences among individuals within a population. this is the vital information for plant breeding activities, because proper management of diversity can produce permanent gain in the performance of plant and can safeguard against seasonal fluctuations (sharma, 1998). therefore, the studies on coffee diversity are vital for conservation of genetic resources and improvement of crops. multivariate analysis is a useful tool in quantifying the degree of genotypic divergence among biological populations and to assess the relative contribution of different components to the total divergence levels (murty and arunachalam, 1966; das and gupta, 1984). such a study also permits to select the genetically diverse parents to obtain the desirable recombinant in the segregating populations upon crossing. in the hybridization programs, inclusion of more diverse parents has been observed to increase the chance for obtaining strong heterosis and giving broad spectrum of variability in segregating generations (joshi and dhawan, 1966). yayu forest is one of the afromontane rainforest biosphere reserves, primarily designated for in situ conservation of wild coffea arabica gene pool in southwestern highlands of ethiopian (,dereje likissa, 2014). some morpho-physiological and molecular diversity assessment studies at population level suggested the existence of genetic variability in yayu coffee gene pool (tadesse woldemariam and feyera senebeta, 2008; taye kufa, 2006; esayas aga, 2005; kassahun testate, et al.2013). therefore, systematic and detail characterization of coffee collections at individual level is very important for effective conservation and efficient exploitation of its germplasm through selection and crossing in coffee variety development prorgam. considering these facts, the study was conducted to estimate the extent of genetic variability among collected coffee germplasm in this region using multivariate analysis with respect to quantitative traits. 2. materials and methods 2.1. description of the experimental site the experiment was conducted at metu agricultural research sub-center during the 2018 cropping season. metu is located 600 km away from addis ababa in the southwesterly direction in illubabor zone of the oromia regional state. the sub center is situated at a distance of 3 km from metu town. the geographical location of the sub center is 8°19' 0" n latitude 35°35' 0"e longitude and altitude of 1558 meters above sea level. the mean annual temperature ranges from 12.7 and 28.9 0c with annual rainfall of 1829 mm/annum. the major soil type is nitosols with ph of 5.24 (paulos dubale, 2001). 2.2. experimental materials, design and field management sixty-two coffea arabica germplasm collected from yayu woreda of illubabor zone and two commercially grown check varieties were used for this study (table 1). the study was conducted on six-year old coffee trees during the 2018 main cropping seasons. experiment was laid down in an 8 x 8 simple lattice design. each collections was planted in a single row of six trees using spacing of 2 x 2 m. collections were established under a fast growing sesbania sesban legume shade tree. all other management practices were also uniformly applied for the coffee trees as per the jima agriculture research center recommendation for coffee production. file:///c:/users/user/desktop/diff%20file/coffee%20article/variability%20of%20quantitative%20traits%20in%20limmu%20coffee%20((i)coffea%20arabica(_i)%20l.)%20in%20ethiopia.htm%2320265_bc masreshaw et al. genetic diversity of coffee collections from southwestern ethiopia 143 table 1. description of coffea arabica germplasm collections used in the study. collection district specific collection site collection district specific collection site y63 yayu dogi y95 yayu geri geba y64 yayu dogi y96 yayu geri geba y65 yayu dogi y97 yayu geri geba y66 yayu dogi y98 yayu geri geba y67 yayu dogi y99 yayu geri geba y68 yayu sembo y100 yayu geri geba y69 yayu sembo y101 yayu geri geba y70 yayu sembo y102 yayu geri geba y71 yayu sembo y103 yayu geri geba y72 yayu sembo y104 yayu geri geba y73 yayu sembo y105 yayu gordeya y74 yayu sembo y106 yayu gordeya y75 yayu sembo y107 yayu gordeya y76 yayu sembo y108 yayu gordeya y77 yayu sembo y109 yayu gordeya y78 yayu sembo y110 yayu gordeya y79 yayu sembo y111 yayu gordeya y80 yayu sembo y112 yayu gordeya y81 yayu geba y113 yayu degitu y82 yayu geba y114 yayu degitu y83 yayu geba y115 yayu degitu y84 yayu geba y116 yayu degitu y85 yayu geba y117 yayu degitu y86 yayu geba y118 yayu degitu y87 yayu achebo y119 yayu degitu y88 yayu achebo y120 yayu degitu y89 yayu achebo y121 yayu degitu y90 yayu achebo y122 yayu degitu y91 yayu achebo y123 yayu degitu y92 yayu achebo y124 yayu degitu y93 yayu achebo 74110 metu bishari y94 yayu achebo 74112 metu bishari 2.3. data collection during the course of this study data on 25 quantitative traits, included: height up to first primary branch (cm), total tree height (cm), number of main stem node, average inter-node length on orthotropic branch (cm), main stem diameter (mm), canopy diameter (cm), number of primary branches, number of secondary branches, percentage of bearing primary branches (%), number of nodes on primary branches, length of primary branches (cm), average inter-node length on primary branches (cm),leaf length (cm), leaf width (cm), leaf area (cm2), fruit length (mm), fruit width (mm), fruit thickness (mm), bean length (mm),bean width (mm), bean thickness (mm), hundred bean weight(gm), yield per tree (kg), coffee berry disease and rust severity (%) were recorded on tree basis from each coffee collection using the standard procedures of the international plant genetic resources institute (ipgri, 1996) coffee descriptor. 2.4. data analysis 2.4.1. analysis of variance (anova) anova of 8 x 8 simple lattice design was subjected using sas software for each trait. the simple lattice design analysis of variance as structured is stated in table 2 (cochran and cox, 1957). masreshaw et al. east african journal of sciences volume 15 (2): 141-154 144 table 2. analysis of variance (anova) for simple lattice design. source of variations df ss ms f-valus replications (r–1) ssr msr msr/mse genotype (adjusted) (k2–1) ssg msg msg / mse blocks with in replication (adj.) r (k–1) ssb msb msb/mse intra block error (k–1)(rk–k–1) sse mse note: r = number of replication; g = number of genotypes; df = degrees of freedom; k = block sizes; ss = sum squares; ms = mean squares; ssr = sum squares of replication; ssg = sum square of genotypes; ssb = sum square of block; sse = sum square of error; msr = mean of square due to replication; msg = mean of square due to genotypes; msb = mean square of block within replication; and mse = mean of square due to error. simple lattice design anova was computed using the following model: yijk = µ + ti + β j+ χ k (j) + σijk where, yijk = response of y trait from the ith collection under jth replication and kth level of incomplete blocks within replications; µ = overall mean effects; ti = effects of ith level of collections; βj = effects of jth level of replication; χk(j) = effects of kth level of incomplete blocks within replications; and σijk = the residual or random error component. 2.4.2. multivariate analysis multivariate analysis techniques viz. cluster analysis and principal component analysis (pca) was employed using sas statistical package software. the numbers of clusters were determined by looking into three statistical approaches, namely, pseudo-f, pseudo-t2 and cubic clustering criteria which is suggested by copper and miligan (1988). accordingly, the number was decided where local peaks of pseudo-f statistics and cubic clustering criteria combined with small values of pseudo-t2 statistics followed by a larger pseudo-t2 statistics for the next cluster fusion. divergence analysis (d2) was used to estimate the genetic distance/divergence of the coffee germplasm collections or to classify the divergent collections into different groups and it also measures the forces of differentiation at inter-cluster levels and determines the relative contribution of each component trait to the total divergent (sharma et al., 1998). genetic divergence between clusters was determined using the generalized mahalanobis’s d2 statistics (mahalanobis, 1936) formula: d2ij = (xi-xj) s-1 (xi-xj); where, dij2 = the distance between class i and j; xi-xj = the difference in the mean vectors of the two populations (class i and j); and s–1 = the inverse of pooled variance covariance matrix. the d2 values obtained for pairs of clusters were considered as the calculated values of chi-square (χ2) and tested for significance both at 1% and 5 % probability levels against the tabulated value of (χ2) for 'p' degree of freedom, where p is the number of traits considered (singh and chaudhary, 1987). the principal components analysis (pca) was employed in order to minimize the traits into a new set of linearly combined measurements and to identify the traits contributing large part of the total variation among the collections. the analysis was performed using sas software. in this analysis, only principal components with eigen values greater than one were considered as important for the total variations. 3. results and discussion 3.1. analysis of variance analysis of variance (anova) revealed the existence of significant (p<0.05) variation among coffee germplasm collections for most of the quantitative traits studied except for height up to first primary branch, number of main stem nodes, percentage of bearing primary branches, leaf width, leaf area and fruit length (table 3). the existences of sufficient variability among the evaluated materials create immense opportunity to bring considerable improvement through selection and cross breeding in the future coffee improvement program. therefore, the possible reason for the existence of considerable genetic diversity in the present study will be attributed to either out crossing nature of the crop through different pollinators (meyer, 1965; gezahegn berecha, et al., 2014), or to the gene flow through dissemination of seeds and seedlings from place to place by means of wild animal and human being (esayas aga, et al. 2005; feyera senbeta, 2006). the significant difference observed for measured quantitative traits in this investigation were in agreement with the finding of earlier authors who reported considerable genetic variability within the arabica coffee germplasm for yield, disease resistance and growth characters (bayetta belachew, 1997; olika kitila et al., 2011; getachew weldemichael et al., 2013; ermias h/mariam, 2005; yigzaw desalegn, 2005; lemi beksisa and ashenafi ayano, 2016; tadesse benti et al., 2021; lemi et al., 2021). file:///c:/users/user/desktop/diff%20file/coffee%20article/variability%20of%20quantitative%20traits%20in%20limmu%20coffee%20((i)coffea%20arabica(_i)%20l.)%20in%20ethiopia.htm%23t2 masreshaw et al. genetic diversity of coffee collections from southwestern ethiopia 145 table 3. analysis of variance for 25 traits of 64 coffee collections studied at metu during 2018. trait mean squares re (%) cv (%) replication (1) treatment (adjusted)(63) blocks within rep.(adj.)(14) error (49) hup 162.00 12.23 ns 13.97 9.35 103.38 11.46 tph 182.41 603.20* 287.13 321.80 97.60 8.61 nmsn 328.64 8.00 ns 7.28 6.40 100.29 7.84 ailm 7.41 0.48** 0.52 0.17 111.01 7.12 sd 582.68 17.05** 9.24 2.15 101.24 3.10 cd 264.21 212.84** 350.75 63.65 135.14 4.80 npb 498.49 25.12** 27.02 9.45 123.49 6.44 nsb 506.02 1469.03** 671.90 155.13 100.23 8.65 pbpb 2195.53 164.22ns 133.71 130.6 100.01 34.75 nnpb 14.99 3.03** 5.68 0.34 145.75 3.27 alpb 834.36 66.18* 173.39 39.57 149.5 8.21 ailpb 8.30 0.38** 0.49 0.04 122.00 4.48 ll 2.95 0.52** 0.46 0.18 105.44 3.47 lw 5.61 0.15 ns 0.44 0.10 151.16 5.37 la 690.99 23.41 ns 35.72 17.13 111.25 8.70 fl 28.69 0.90 ns 1.54 0.58 120.16 4.57 fw 23.14 0.70** 1.31 0.36 136.86 4.14 ft 24.61 0.50** 1.24 0.28 150.11 4.30 bl 2.91 0.56** 0.24 0.13 98.46 3.31 bw 0.66 0.09** 0.07 0.03 109.27 3.00 bt 0.13 0.04** 0.03 0.02 100.78 3.70 hbw 20.08 4.34** 1.93 0.98 101.56 5.60 cbd 45.55 165.48** 153.72 86.54 106.87 89.45 clr 129.38 61.14** 49.25 26.21 108.29 49.21 yld 0.045 0.010* 0.007 0.006 100.420 21.00 note: hup = height up to first primary branches; tph = total plant height; nmsn = number of main stem nodes; ailms = average inter-node length of main stem; sd = stem diameter; cd = canopy diameter; npb = number of primary branches; nsb = number of secondary branches; pbpb = percentage of bearing primary branches; nnpb = number of nodes of primary branches; alpb = average length of primary branches; ailpb = average inter node length of primary branches; ll = leaf length; lw = leaf width; la = leaf area; fl = fruit length; fw = fruit width; ft = fruit thickness; bl = bean length; bw = bean width; bean thickness; hbw = hundred bean weight; cbd = coffee berry disease; clr = coffee leaf rust; df = yld = yield per tree; and re = relative efficiency. ** = highly significant at p<0.01; * = significant at p<0.05; and ns = non-significant. cv = coefficient of variation. 3.2. cluster analysis out of the 25 study traits, 19 were significantly different among coffea arabica collections. therefore, cluster analysis was employed using 19 quantitative traits to categorized 64 coffee collections into seven clusters (table 4 and figure 1).the distribution pattern revealed that, cluster-i contained the highest number of collections (19) followed by cluster-iii (16), cluster-ii (13), cluster-iv (7), cluster-v (4), cluster-vi (4) and cluster-vii (1). in cluster analysis, if the categorization is successful, individuals within (homogenous) shall be closer and different clusters (heterogeneous) shall be farther apart. cluster-i contained two coffee collections collected from each of dogi and gerigeba site, five from sembo, three collections from each of geba, achebo and degitu collection sites and one collection from gordiya. cluster–ii consisted of four collections from degitu, three collections from achebo, two collections each from gerigeba and sembo, one collection from each of geba and gordiya. similarly, cluster-iii was comprised of two standard check varieties (74110 and 74112) masreshaw et al. east african journal of sciences volume 15 (2): 141-154 146 originated from metu and one collection collected from each dogi, geba and achebo sites, three collections from each geri geba, degitu and goridya and two collections from each sembo and goridya. on the other hand, cluster-iv had seven collections collected from dogi, sembo, achibo and degitu, each with one collection and geri geba with three collections. moreover, cluster-v and vi each possessed four collections collected from dogi, sembo, geba and degitu. however, the last cluster (vii) was unique to single collection, which was collected from degitu site. in this clustering pattern, there were coffee collections collected from the same area of collection sites grouped in to different clusters; the possible cause might be difference in their genetic back ground and gene flow through exchange of seeds or seedlings. there were also collections collected from different site grouped in the same cluster, which was also probably due to originally from the same sources. therefore, most of the collections were grouped together both from their source and outsource area of collection site, which might be due to selection pressure and genetic drift (amsalu ayana and endashaw bekele, 1999). this is almost certainly attributable to the continuous movement of coffee seed and seedlings from one site to another by humans or animals. from this finding, it can be concluded that the selection of coffee collections for hybridization should be based on genetic diversity. this is more under lined by bayeta belachew (2001), who suggested as morphological variation is more considerable than collection area as an indicator of genetic diversity in coffee. the current finding is in agreement with mesfin and bayetta (2005) who grouped 100 hararghe coffee accessions in to six clusters. olika kitila et al. (2011) and getachew weldemichael et al. (2013) each grouped 49 limu coffee collections into four and five clusters, respectively.moreovere, lemi et al.(2021) also grouped another set of limu coffee collections in to three clusters. table 4. the distribution of 64 coffee collections in seven clusters based on d2 analysis evaluated at metu in 2018. cluster no. no. acc. % collections i 19 30 y101, y77, y67, y72, y91, y88, y63, y68, y107, y94, y82, y114, y83, y76, y112, y84, y79, y122, and y103 ii 13 20 y111, y115, y87, y106, y121, y81, y90, y71, y100, y116, y89, y104, and y80 iii 16 25 y69, y86, y105, y66, y108, y97, y78, y117, y98, y93, y109, 74112, 74110,y99, y110, and y120 iv 7 11 y96, y124, y95, y75, y102, y92 and y64 v 4 6 y70, y85, y65 and y123 vi 4 6 y119, y113, y73 and y74 vii 1 2 y118 3.2.1. cluster characterization using quantitative traits mean performance of different clusters for the 19 traits (table 5) reflected that the coffee collections in clusteriv were the high yielder (0.39 kg per tree) followed by cluster-ii and iii each produced the same yield (0.38 kg per tree). besides, collections in cluster-vi exhibited the highest total plant height, stem diameter, canopy diameter, number of primary branches, number of secondary branches, number of nodes of primary branches, average length of primary branches, average inter-node length of primary branches, leaf length and bean width. interestingly, collections in this cluster showed the lowest coffee berry disease severity level, which is an advantage for coffee breeder to develop improved varieties through making use of these collections. furthermore, collections in this cluster also gave medium values for the rest of traits. collections in cluster-i showed medium mean values for all the traits except for number of primary branches, which had the lowest, mean values. similarly, the highest cluster mean was found for fruit width, fruit thickness, bean thickness and hundred bean weights in cluster-ii and number of nodes of primary branches in cluster-iii, while all the rest of the traits produced medium cluster mean value in these two clusters (cluster-ii and iii). cluster-iv had the highest cluster mean for yield per tree and coffee leaf rust severity, while the remaining traits scored medium mean values except lowest in stem diameter. even though, the collections in cluster-iv had relatively highest coffee leaf rust severity level, unfortunately the score value (13 %) lays in moderately resistant level, which will not be difficult for future improvement of those collections in disease-resistant point of view. cluster-v possessed collections with longest bean length, but with shortest total plant height, average internode length of main stem node, average length of primary branches, average inter-node length of primary branches, narrow canopy diameter, lowest number of masreshaw et al. genetic diversity of coffee collections from southwestern ethiopia 147 secondary branches and number of nodes of primary branches, while the remaining traits showed medium values. in contrast, cluster-vii which comprised of only one collection was mainly characterized by shortest leaf length and bean length, narrow fruit width, fruit thickness, bean width and bean thickness, lowest for hundred bean weight, coffee leaf rust severity and yield per tree, in contrast the remaining traits had moderate values except having the longest average internodes length of main stem node and highest coffee berry disease severity level. the highest value of coffee berry disease severity in this collection will be difficult to breeders for future improvement of traits in coffee. table 5. mean values of 19 traits for seven clusters of 64 coffee collections evaluated at metu in 2018. traits cluster i ii iii iv v vi vii tph 197.7 214.07 222.29 201.81 171.44* 226.83** 223.35 ailms 5.79 5.81 6.13 5.74 5.16* 6.03 6.30** sd 48.92 50.3 47.87 47.79* 47.96 51.96** 50.25 cd 167.01 168.62 166.72 161.12 153.79* 181.72** 170.35 npb 45.31* 49.54 50.38 45.62 43.08 50.52** 49.14 nsb 143.14 172 128.27 105.39 125.91* 194.28** 193.15 nnpb 17.65 17.83 18.22** 17.57 17.26* 18.01 18.1 alpb 75.51 76.92 77.58 73.58 72.80* 85.72** 77.67 ailpb 4.46 4.48 4.41 4.36 4.31* 4.95** 4.39 ll 12.3 12.03 12.24 12.12 12.36 12.77** 11.02* fw 14.48 14.64** 14.56 14.06 14.25 14.25 13.70* ft 12.32 12.52** 12.38 11.91 12.16 12.09 11.56* bl 10.96 10.99 10.87 10.69 11.03** 10.85 9.94* bw 6.51 6.61 6.52 6.54 6.51 6.65** 6.28* bt 3.93 4.00** 3.96 3.94 3.92 3.92 3.69* hbw 17.67 18.30** 17.6 17.04 17.63 17.83 14.25* cbd 9.31 10.37 10.06 8.59 15.19 6.23* 60.87** clr 9.06 11.73 9.74 13.00** 10.6 12.53 8.22* yld 0.37 0.38 0.38 0.39** 0.34 0.35 0.25* lowest mean 0.37 0.38 0.38 0.39 0.34 0.35 0.25 highest mean 197.70 214.07 222.29 201.81 171.44 226.83 223.35 overall mean 42.23 45.32 43.17 40.07 39.25 48.29 49.08 note: tph = total plant height; ailms = average inter-node length of main stem; sd = stem diameter; cd = canopy diameter; npb = number of primary branches; nsb = number of secondary branches; nnpb = number of nodes of primary branches; alpb = average length of primary branches; ailpb = average inter-node length of primary branches; ll = leaf length; fw = fruit width; ft = fruit thickness; bl = bean length; bw = bean width; bt = bean thickness; hbw = hundred bean weight; cbd = coffee berry disease; clr = coffee leaf rust; and yld = yield per tree. **,* represents maximum and minimum values, respectively. 3.2.2. genetic divergence (d2) the values of pair wise average intra and inter-cluster divergence (d2) among 64 coffee collections in seven clusters based on their 19 quantitative traits are presented in table 6. accordingly, the inter-cluster distances in all the cases were greater than the intracluster distances suggesting wider diversity among the collections of the distant clusters. the intra-cluster degree of diversity was relatively maximum in cluster v and vi (5.55), indicating that the collections in cluster v and vi were a little bit heterogeneous as compared to those in other clusters. generally, the range of intracluster values indicated homogeneous nature of the genotypes within the clusters. the chi-square test revealed the existence of highly significant differences among the paired inter cluster distance except cluster i and ii, i and iii, i and iv, i and v, ii and iii, ii and vi, iii and iv and vi and v. the maximum inter-cluster distance was found between cluster-iv and vii (396.99) followed by cluster-v and vii (374.31), cluster-i and vii (260.90), and clusteriii and vii (245.11); while, the lowest inter-cluster distance was recorded between cluster-i and iii (12.13) followed by cluster-ii and vi (20.55), cluster-iv and v (22.01), and clusters-i and v (23.70). the highest value of intercluster distance indicated that the accessions belonging to these cluster were far diverged. on the other hand, the lowest cluster distance indicates a close relationship between the accessions. masreshaw et al. east african journal of sciences volume 15 (2): 141-154 148 cluster-iv was found divergent from cluster-vii chiefly due to number of secondary branch, coffee berry disease, coffee leaf rust, plant height and yield per tree, indicating maximum contribution of these traits towards the divergence. similarly, cluster-v was divergent from cluster-vii mainly for total plant height, average internode length of main stem node, bean length, and coffee berry disease severity. on the other hand, intra cluster mean performance for most of the traits in cluster-vi was maximum and greater than the mean of cluster-vii except for average inter-node length of main stem node. the highest mean value in cluster-vi indicates the role of those traits towards the divergence between clustervi and vii. in this perspective, jagadev et al. (1991) stated that the traits contributing maximum towards the divergence should be given greater emphasis for deciding the type of cluster for the purpose of further selection and choice of the parents for hybridization. the collections of distant clusters could be used in hybridization program to obtain a higher heterotic response in the hybrids and a wide range of variation among the segregate. the highest inter-cluster distance is found between clusters-iv and vii, suggesting that superior hybrids or recombinants can be realized by crossing between the desirable lines of these clusters. however, the progenies will be high yielder, but they might be susceptible to cbd, because the mean performance of collections in cluster-vii exhibited the highest cbd severity level. hence, the possible alternative to develop superior hybrids or recombinants would be mating between collections found in clusterv & vi followed by cluster-iv and vi. moreover, the heterosis could also be exploited by crossing between collections with moderate diversity like cluster-ii and v, followed by clusterii and iv, i and vi, iii and vi and iii and v. the present result is in support of bayeta belachew (2001) who reported the significance of genetic diversity among parents with respect to geographical origin or morphological traits for maximum heterosis to occur in certain hybrid traits of coffee germplasm. similar reports were also made by szamosi et al. (2010) who found heterosis by crossing between melon genotypes with higher inter cluster distance. table 6. pair wise average intra (bold) and inter cluster divergence values (d2) among 64 coffee collections in seven clusters based on their 19 quantitative traits tested at metu in 2018. cluster i ii iii iv v vi vii i (2.43) 24.23 12.13 25.05 23.10 73.07** 260.90** ii (3.19) 23.70 77.40** 81.23** 20.55 172.74** iii (2.77) 29.14 49.84** 61.63** 245.11** iv (4.43) 22.01 141.41** 396.99** v (5.55) 160.73** 374.31** vi (5.55) 160.86** vii (0.00) note: ** = highly significant at p<0.01, 2 = 34.80, p<0.05, 2 = 28.87. masreshaw et al. genetic diversity of coffee collections from southwestern ethiopia 149 figure 1. dendrogram depict 64 coffee accession in seven clusters. 3.3. principal component analysis (pca) the principal component analysis was done using 19 quantitative traits with the intention of minimizing the dimensionality of large number of interrelated traits in a given data set and retaining maximum information about the genetic variation. accordingly, the first seven principal components with eigen values exceeding one were responsible for about 74.94 % of the total variation among the coffee collections. out of the entire variations, the first two principal components accounted for the maximum variation (35.32%) among the coffee collections (table 7 and figure 2). the first principal component that accounted the highest total variation (21.99%) was due to the chief contribution of positive discriminatory traits like the average length of primary branches, fruit width, fruit thickness and hundred bean weights. the considerable variation observed in the second principal component (13.33% of the total variation) was attributed to average inter-node length of primary branches, average length of primary branches, canopy diameter, bean width and bean thickness. quantitative traits, which had substantial contribution to the third principal component that accounted for 12.99% total variation, were total plant height, number of primary branches, and number of nodes of primary branches, leaf length and bean length. similarly, variation in total plant height, coffee leaf rust, average inter-node length of main stem node and stem diameter had a great deal of contribution to the fourth principal component. the variation in the fifth principal component was also, attributed to traits like number of secondary branches, number of nodes of primary branches, bean length and yield per tree. on the other hand, average inter-node length of main stem node, number of nodes of primary branches, average length of primary branches, fruit width and fruit thickness were predominantly influenced the variation in the sixth principal component. moreover, quantitative traits like coffee berry disease, leaf length and number of nodes of primary branches had influenced the seventh principal component. consistent with this finding many investigators also found comparable result from different arabica coffee germplasm (mesfin kebede and bayetta belachew, 2005; olika kitila et al., 2011; getachew weldemichael et al., 2013; lemi beksisa and ashenafi ayano, 2016;lemi et al.,2021) the first and second principal components accounted for more than one third of the total variations (35.32%). chahal and goal (2002) inferred that characters with the largest absolute values closer to unit within the first principal component influence the clustering more than those with lower absolute values closer to zero. therefore, in the current investigation discrimination of the coffee collections into different cluster was mainly due to average inter-node length of primary branches, average length of primary branches, canopy diameter, fruit width, fruit thickness, bean width, bean thickness and hundred-bean weight. vii vi iv i ii i ii v masreshaw et al. east african journal of sciences volume 15 (2): 141-154 150 table 7. eigenvectors and eigen values of the first seven principal components for 19 quantitative traits of 64 coffee collections evaluated at metu in 2018. quantitative traits pc 1 2 3 4 5 6 7 tph 0.27 0.18 0.32 0.37 –0.06 –0.22 –0.03 ailms 0.21 0.19 0.15 0.31 –0.27 –0.40 0.12 sd 0.05 0.23 0.28 –0.40 0.22 –0.16 –0.06 cd 0.24 0.31 0.15 –0.25 0.10 –0.18 0.08 npb 0.18 0.09 0.32 0.28 0.02 0.06 –0.19 nsb 0.13 0.25 0.19 –0.32 0.34 0.15 0.12 nnpb 0.10 –0.12 0.31 0.24 0.29 0.35 –0.31 alpb 0.33 0.30 –0.07 0.03 –0.02 0.33 –0.03 ailpb 0.24 0.34 –0.28 –0.14 –0.25 0.07 0.16 ll 0.12 0.26 –0.30 –0.17 –0.06 0.00 –0.44 fw 0.36 –0.23 0.04 –0.04 –0.16 0.33 0.08 ft 0.34 –0.22 0.06 –0.11 –0.18 0.32 0.13 bl 0.20 0.00 –0.43 0.14 0.36 –0.10 –0.07 bw 0.29 –0.31 0.01 –0.17 0.14 –0.05 0.19 bt 0.27 –0.34 –0.01 –0.06 0.23 –0.28 0.08 hbw 0.32 –0.16 –0.26 0.13 0.22 –0.29 0.05 cbd –0.15 0.17 0.03 0.17 0.15 0.15 0.73 clr 0.02 0.21 –0.31 0.37 0.24 0.23 0.04 yld 0.15 –0.08 –0.08 –0.06 -0.45 0.00 0.01 eigen values 4.18 2.53 2.30 1.69 1.31 1.16 1.06 total variance (%) 21.99 13.33 12.09 8.91 6.9 6.13 5.58 cumulative variance (%) 21.99 35.32 47.42 56.33 63.23 69.35 74.94 note: pc = principal component; tph = total plant height; ailms = average inter-node length of main stem; sd = stem diameter; cd = canopy diameter; npb = number of primary branches; nsb = number of secondary branches; nnpb = number of nodes of primary branches; alpb = average length of primary branches; ailpb = average inter node length of primary branches; ll = leaf length; fw = fruit width; ft = fruit thickness; bl = bean length; bw = bean width; bt = bean thickness; hbw = hundred bean weight; cbd = coffee berry disease; clr = coffee leaf rust; and yld = yield per tree. figure 2. biplot of the first two principal components for 64 arabica coffee collections. masreshaw et al. genetic diversity of coffee collections from southwestern ethiopia 151 4. conclusions characterization of the coffee collections using a multivariate technique revealed the availability of sufficient genetic variability among coffee collections. the distribution pattern of the coffee collections into seven clusters demonstrated the presence of considerable genetic divergence among the tested collections. hence, crossing of these collections in a breeding program would result in superior hybrids. principal component analysis revealed that the first seven principal components were responsible for about 74.94 % of the total variation. average internode length of primary branches, average length of primary branches, canopy diameter, fruit width, fruit thickness, bean width, bean thickness and hundred bean weights contributed to the observed variability among collections. the results imply that these traits could be used for selection of collections and crossing in coffee improvement program. moreover, future evaluation of these coffee collections with respect to coffee quality traits would be indispensable using biochemical and molecular techniques. 5. acknowledgments the author acknowledges jimma agricultural research center and ethiopian institute of agricultural research for availing the resources and facilities for conducting the research. special appreciation also goes to metu agricultural research sub-center for material support, technical assistance and cooperation in the field during the entire period of data collection. 6. references amsalu ayana and endashaw bekele. 1999. multivariate analysis of morphological variation in sorghum (sorghum bicolor (l.) moench) germplasm from ethiopia and eritrea. genetic resources and crop evolution, 46: 273–284. bayetta belachew, ashenafi ayano and tadesse benti. 1993. screening of arabica coffee collection for bebeka environment. 21st international conference on coffee science, 11th–15th september 2006. montpelier, france. bayetta belachew. 2001. arabica coffee breeding for yield and resistance to coffee berry disease (colletotrichum kahawae). phd dissertation, university of london, britain. csa (central statistical authority 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15–25. tadesse benti, endale gebre, kassahun tesfaye, gezahegn berecha, lashermes, p., et al. 2021. genetic diversity among commercial arabica coffee (coffea arabica l.) varieties in ethiopia using simple sequence repeat markers. journal of crop improvement: 35(2): 147–168. tadesse woldemariam, denich, m., demel teketay and vlek, p.l.g. 2002. human impacts on coffea arabica l. genetic pools in ethiopia and the need for its in situ conservation. engels, j., rao, m., brown, v.r. and jackson, m.t. (eds.). managing masreshaw et al. genetic diversity of coffee collections from southwestern ethiopia 153 plant genetic diversity, ipgri publication, rome. pp: 237–247. tadesse woldemariam. 2003a. vegetation of yayu forest in sw ethiopia: impacts of human use and implications for in situ conservation of wild coffea arabica l. populations. phd dissertation, ecology and development series, no.10, cuvillier verlag, gottingen. tadesse woldemariam and feyera senebeta. 2008. sustainable management and promotion of forest coffee in bale, ethiopia. bale eco-region sustainable management programme sos sahel/ farmafrica, addis ababa, ethiopia. taye kufa. 2006. ecophysiological diversity of wild arabica coffee populations in ethiopia: growth, water relations and hydraulic characteristics along a climatic gradient. phd dissertation, ecology and development series, no.46.cuvillier verlag, gottingen. pp. 305. taye kufa, 2010. environmental sustainability and coffee diversity in africa. ico world coffee conference, guatemala city. http://dev.ico.org/event_pdfs/wcc2010/presen tationswcc-2010-kufa-notese-pdf. accessed on 10 november 2011. united states department of agriculture (usda). 2020. coffee annual report: global agricultural information network, usda foreign agricultural service report number: et20200004. yigzaw desalegn, 2005.assessment of genetic diversity of ethiopian arabica coffee accessions using morphological, biochemical and molecular markers. a phd dissertation, university of the free state, south africa. pp. 197. http://dev.ico.org/event_pdfs/wcc2010/presentationswcc-2010-kufa-notese-pdf http://dev.ico.org/event_pdfs/wcc2010/presentationswcc-2010-kufa-notese-pdf masreshaw et al. east african journal of sciences volume 15 (2): 141-154 154 ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(1): 57–68 licensed under a creative commons *corresponding author: galatasitota@yahoo.com attribution-noncommercial 4.0 international license. adaptation of the “brief family relationship scale” for measuring perceived quality of family relationship in the ethiopian context galata sitota1* and belay tefera2 1college of education and behavioral sciences, haramaya university, p.o. box 138, dire dawa, ethiopia 2college of education and behavioral studies, addis ababa university, p.o. box 33617, addis ababa, ethiopia abstract background: family psychology is in its infancy in ethiopia mainly because local tools that assist in research and intervention are non-existent. as a result, family issues, which are vital to human development, are understudied in this context. objective: this paper presents an adaptation study of the “brief family relationship scale” (bfrs) that purports to measure perceived quality of family relationship. three specific issues were addressed in the validation process: establishing scale reliability, identifying the underlying factor structures, and evidence for validity. materials and methods: in the study, a sample of 101 (46 males and 55 females) who are working in government offices in addis ababa participated. procedures involved forward and backward translation of the english version of the scale into the local (amharic) language, establishing content validity through expert ratings, administration of the scale to the target groups and then successive validation measures employing “satisfaction with family life scale” as an anchor variable. results: the findings indicated that the full-scale (α = 0.70) as well as the three sub-scales (cohesion α = 0.86, expressiveness α = 0.69, and conflict resolution α = 0.60) have an acceptable reliability index. validity of the scale was checked through correlation analysis between the anchor variable and brief family relationship scale (bfrs) yielded a significant value. exploratory factor analysis has confirmed the three original factor structure of the scale, explaining a total of 48.2% of the variance. following exploratory factor analysis (efa), confirmatory factor analysis (cfa) was made to cross-check the obtained three dimensions. the modified index of cfa confirmed that, the comparative fit index (cfi), goodness of fit index (gfi) (gfi) and root mean square error of approximation (rmsea) are within the desired minimum range. these values suggest that, after the removal of 3 items from the initial 16-items, the previously established domains were confirmed. conclusion: it is concluded that the scale has reasonable psychometric properties; as a result, it could be useful for studies and interventions for family relationship issues in ethiopian context. a further adaption process could be done on adolescents to make the scale valid for other age groups. keywords: cohesion; conflict; ethiopia; expressiveness; family relationships 1. introduction family is an active whole, comprised of constantly changing interrelationships in which each person in the family impacts the others across a generation (segrin and flora, 2018). for example, according to family system theory, a family is made up of interrelated individuals, and each individual has an expected and recurrent impact on the other members of the family, where the process of influencing each other never ends even as most of families behaviors are passed down to their children (johnson and ray, 2016). according to family system theory, an individual's behaviors should be understood in mailto:galatasitota@yahoo.com galata and belay east african journal of sciences volume 16(1): 57–68 58 the context of family relationships. beliefs, values, emotional warmth, organization, and communication among family members all appear to be intertwined. that is to say, an individual's behavior cannot be explained separately from his or her family environment; thus, each family member's positive and negative behavior is a mirror of his or her family environment(johnson and ray, 2016). healthy family relationships foster trust and respect, which is shown in each family member's warmth, love, affection, support, and care. the quality of family interactions, for example, in terms of closeness between parents, parents and children, and among children themselves, has a significant impact on each family member's life (olanrewaju et al., 2015). supportive and nurturing family relationships contribute to wellbeing while abusive and tense family relationships deter family stability and health (thomas et al., 2017). evidences indicate that togetherness, acceptance, commitment, resilience, affection, support, communication, sharing activities, appreciation, and conflict management skills are the qualities that promote healthy relationships within a family (triana et al., 2019). because a family cannot be described without considering the relationships among its members, understanding family relationships and quality of life requires use of family functioning measures having proper psychometric properties. there are different measures of family relationship scale today that are with good psychometric properties and, hence, widely used for diagnosing family dynamics including the “brief family relationship scale” (bfrs). the “brief family relationship scale (fes)” was adapted from the ‘relationship dimension’ of the “family environment scale” that was developed by moos and moos in1986 and consisted of 90 true/ false sorts of items that are organized into ten subscales. of the ten dimensions of the scale, one is the ‘relationship dimension’ component that in turn is composed of three subscales: cohesion, expressiveness, and conflict (oliver et al., 1988). out of the 90 items that make up the ‘family environment scale’, 27 items represent family relationship dimension. from adolescence through adulthood, the scale has been used to assess the family environment from the views of several informants inside the family, as well as from a single individual among respective family members (charalampous et al., 2013). that is, among the particular family members an individual over 11/12 years old can fill out the questionnaire representing his/her families. this also explains why the present instrument validated on adults though it was adapted on individuals from 12 to 18 years old. in sum, the scale can be utilized on both adolescents and adults. the scale was designed using the family systems theory (fst) as framework, which views a family as a small group of interconnected and interdependent individuals. despite the widespread use of fes in family environment research, there has long been a debate about the instruments' psychometric qualities, including reliability and validity. for example, oliver et al. (1988) stated that because scores on the family environment scale have been shown to vary as a function of age, socioeconomic status of respondents and family size, there is a good reason to suppose that its factor structure is not necessarily stable across samples and varies as a function of characteristics of samples. with the same token, from its origin the scale has low to high reliability scores for different dimensions of the scale especially expressiveness/ communication and conflict. for example in terms of reliability, the originally reported alpha coefficients for each subscale ranged from .64 to .79 with the acceptable benchmark to be generally above .60 (charalampous et al., 2013). due to this and other factors, fok et al. (2014), have adapted the ‘brief family relationship scale’ having 16 items with three dimensions (cohesion, expressiveness, and conflict) from the relationship dimension of the family environment scale. the brief family relationship scale got the present name after the family relationship dimensions of 27 items were tried out on alaska native youth, usa. alaska native communities are indigenous people living in alaska, usa, barnhardt (2018). the common ethnic groups in alaska include eskimos, indians, and aleuts, together known as alaska natives. the large majority of non-native people are migrants from the lower 48 states, along with increasing numbers of asian and latin. rural alaska is primarily populated by alaska natives who live in settlements with populations ranging from 25 to 5,000 people. despite the fact that an increasing number of native people dwell in the state's urban areas, the labels "rural" and "native" are commonly interchanged. alaska natives that live in rural locations have a distinct and distinct way of life (barnhardt, 2018). hence, brief family relationship scale was tested for psychometric properties and internal structure with participants aged 12 to 18 years old; predominately alaska native adolescents from rural, remote communities in usa (fok et al., 2014). results demonstrated that a subset of the adapted items function satisfactorily, a threegalata and belay brief family relationship scale for measuring quality of family relationship 59 response alternative format (“not at all” “somewhat’’ and “a lot’’) provided meaningful information, and the subscales’ underlying structure is best described through three distinct first-order factors, organized under one higher-order factor. convergent and discriminant validity of the brief family relationship scale was assessed through correlational analysis. the scale with 16-items has acceptable cfa fit, χ2 (101) = 164.9, χ2 /df = 1.63, gfi = 0.93, cfi = 0.95, and rmsea = 0.05. internal consistency was acceptable for cohesion (α = 0.83) and conflict (α = 0.80) and for the full-scale bfrs (α = .88) and expressiveness (α = 0.65) (fok et al., 2014). the scale has also good relationship with anchor variables communal mastery family scale scores (r = 0.51, p < 0.01), the reasons for life scale scores (r = 0.48, p < 0.01) (fok et al., 2014). despite the strong psychometric properties of bfrs, evidence is lacking as to how far it would persist with these features in contexts like ethiopia. ethiopia retains a culture in which marriage and family are highly valued, extended family is the norm, the different religions, widely articulate divergent views regarding matrimonial issues, the status of women and the roles each family members purport to play. the climatic and ecological conditions are quite varied and variations in ethnic and cultural makeup of the country, too, are equally high. besides this, ethiopia is also among the countries that follow collectivist cultural orientations (nsamanang, 2010). given all these diversities in ethiopia, it is not feasible to use imported instruments without validating them against the ethiopian context. basically, the scale was developed and being used in the western context where the culture of the society appreciate independence over interdependence, competition over cooperation, better technological advancement, better economic development and etc. whereas in ethiopia context things are different. for example, the value family put to its members’ interaction, communication, supporting each other, providing sympathy to each other, when need be, to mention a few. hence, it is worthy then to conduct this validation because of two major reasons. firstly, even though the scale has met the statistical qualities of a standardized instrument, to the best knowledge of the researchers the present instrument has not been validated in the ethiopian context particularly in amharic language. incase if validated so far, given the nature of ethiopian diversity in terms of language and culture, it is no doubt that further research needs to be conducted until established knowledge will be obtained as regards the scale. secondly, since its adaptation in 2014, in usa, there is no data base review evidence that indicate the validation of the brief family relationship scale in another context in general and in ethiopian context in particular specifically in amharic language. therefore, the scale is worth validating in the ethiopian context. ultimately, the following specific objectives were forwarded for the scale validation: 1. examine the internal consistency of the brief family relationship scale; 2. assess the evidence for the (content, construct, divergent and discriminant) validity of the brief family relationship scale and 3. explore the underlying structure of the brief family relationship scale by employing exploratory and confirmatory factor analysis model employed for scale adaptation process in fact, there is no globally agreed-upon procedure for validating instruments in a different cultural context. however, during the current validation exercise, (gjersing et al., 2010)'s model for the adaptation of research instrument in diverse cultures was used. according to this model, the instrument/scale validation process should at least include checking item equivalency, back-and-forth instrument translation, synthesizing the translated version, expert evaluation, and finally employing exploratory and confirmatory factor analysis. 2. materials and methods 2.1. design a cross-sectional research design was employed to facilitate the present instrument validation study. the selected design was found to be appropriate because it allowed involving participants from a wider spectrum of age ranges; which in the present case is 2060 years. the design is also relatively inexpensive and takes little time to conduct. in an event where participants of different age groups like the present study and one-time data collection is planned, the appropriate research design is cross sectional research design (levin, 2006). 2.2. study area addis ababa, the capital city of ethiopia, was the study area where different international organizations are based. since addis ababa is the capital city of ethiopia, it is possible to find diversity of adults working in government offices who came from different corners of the country in such way that it is possible to deduce that the present galata and belay east african journal of sciences volume 16(1): 57–68 60 adaption process reflects the inclusive features of the ethiopian situation. 2.3. participants addis ababa has ten sub-cities of which kirkos and nefas-silk are amongst them. kirkos sub-city has a population of 235,441 (male: 110,069, female: 125,372) while nefas-silk has an estimated population of 335, 74 (male: 158,126, female: 177,614) (aklilu and necha, 2018). concerning sample size determination, suggestion from some validation experts was taken into account. for example, comrey (2013) suggested a range of minimum sample sizes, from 50 (very poor) to 1,000 (excellent) and advised researchers to obtain sample sizes larger than 500. gorsuch (1988) characterized sample sizes above 200 as large and below 50 as small. however, tabachnick and fidell (2007) suggested 5 people for 1 item ratio. keeping in view the recommendations of these experts, the present study considered a total sample of 101 adults (46 males and 55 females). the data for this study were obtained from the aforementioned sub cities, kirkos and nefas silk. there were only ten sub cities in addis ababa before data for this study was collected, and one sub city was added only after the data for the study was collected. accordingly, the two sub cities were chosen using a lottery method among the city's ten sub cities then. consequently, from the government employers in the kirkos sub city 44, and from nefas silk sub city 57 employees were selected randomly balancing both sexes respectively. as a reminder, the researchers did not choose to be careful in selecting the sub cities for the current study because government employers' economic and living statuses in addis ababa are virtually identical, and this is why the lottery method was used to select the previously mentioned sub cities. 2.4. measures two measures were employed for the validation purpose: the main scale (the brief family relationship scale, bfrs) and the anchor scale (satisfaction with family life scale). the ‘brief family relationship scale’ (bfrs) was adapted from family environment scale in 2014 by (fok et al., 2014) to measure family relationship. the scale has a total of 16 items and three factors namely, cohesion (7 items), expressiveness (3 items), and conflict (6) items respectively. the scale has an overall internal consistency reliability of (α = 0.88). for cohesion factor (α = 0.83), conflict factor (α = 0.80), and for expressiveness (α = 0.65). the brief family relationship scale was scored using a 3-point likert scale and the participants are then required to rate the degree of how much they agree with each of the statements on a scale of 1-5 (with ‘1’ being ‘not at all’, ‘3’being ‘somewhat’ and ‘5’ being ‘alot’). from adolescence through adulthood, the scale has been used to assess the family relationship from the views of several informants inside the family, as well as from a single individual among respective family members (charalampous et al., 2013). that is, among the particular family members an individual over 11/12 years old can fill out the questionnaire representing his/her families. this also explains why the present instrument validated on adults. as regards the meanings of the scale, high score on cohesion dimensions represents better bonding and interaction among family members and vice versa. for expressiveness dimension, high score on expressiveness dimension represents better sharing of ideas and understanding each other among family members and vice versa. items on conflict dimensions will be reverse coded. the ‘satisfaction with family life scale’ (swfl) (zabriskie and mccormick, 2003) is a modified version of the ‘satisfaction with life scale’ used to measure life satisfaction. the swfl scale is composed of five items that require respondents to agree or disagree with global statements about family life on a 7-point likert-type scale ranging from 1 = strongly disagree to 7 = strongly agree. scores are calculated by summing all items and producing satisfaction with family life score with a possible range of 5 to 35. descriptive data for the swfl scale were collected from a variety of family populations and from multiple perspectives, including a parent and young adolescent child (11 to 15 years old) within each family (zabriskie and ward, 2013). the swfl scale appears to measure a single dimension. the consistency of the swfl factor analyses suggests the scale is accurately capturing family satisfaction across time, place, and culture, which supports its possible use as a universal instrument in measuring family satisfaction. across all samples, a consistent unidimensional factor structure was maintained, with cronbach’s alpha ranging from 0.94 to 0.79. evidence of usability, criterion, and construct validity were also established (zabriskie and ward, 2013). the reason for selecting ‘satisfaction with family life scale’ as an anchor scale/ variable is that: (1) similarity of the anchor scale to the main scale in terms of purpose (e.g. both focus on family functioning; that refers to galata and belay brief family relationship scale for measuring quality of family relationship 61 relationship, interaction, communication etc.), content (similarity of some of the contents of the both measures) and approach; (2) robust psychometric properties of this anchor variable, (e.g., very high reliability indices, content and construct validity of the scale); (3) recommendation by experts used in the previous study about content, context, and purposerelevance of the tool to the research setting; for example, brief family relationship scale and family satisfaction scale are theoretically related constructs (devellis, 2003); and (4) its simplicity and feasibility of use. 2.5. procedures validation of the present instrument went through different stages beginning from checking the face and content validity of the scale using three experts in the field. concerning face and content validity of the scale, two phd holders in psychology and one professor from the same discipline were requested to check the scale’s feasibility in light of relevance, likely effectiveness, appropriateness, clarity and conceptual scope where they endorsed the two scales along these criteria. accordingly, the expertise came to agreement that the scales were considered appropriate for use in the stipulated age groups from 12 years onwards confirm to the scale’s original guideline. once decision was reached to use the scales as it is, the scales were then translated forward from english to the native language (amharic) and then backward from the amharic version to english by bilingual language experts, one of whom was a phd in english as a foreign language and the other an ma in amharic language. differences noted in the two english versions were continuously inspected until such time that full congruence was achieved. once equivalence was established in the translations through successive adjustments of phrasing, the scale was administered to the participants of the study. procedure of data collection: after participants of the study were identified, they were asked for the consent of participation to the study and oriented about the purpose and confidentiality of their response. following this, convenient time for participants to fill out the questionnaire was identified. hence, almost all participants were expressed their willingness to fill out the survey questionnaire during their tea break time on weekdays at their work place. in addition, the respondents were encouraged to respond honestly to all items. accordingly, data collection was made as needed. ethical consideration: the data were collected after the consent of the respondent was achieved. confidentiality of the data collected from the participants was assured and guaranteed and the results would be used for academic purposes and nothing more. 2.6. data analysis instrument validation was begun with describing demographic characteristics of participants followed by exploring the internal consistency of the brief family relationship scale and its subscales along with anchor variable (satisfaction with family life scale) using cronbach alpha internal consistency test. to assess the evidence for the validity of the brief family relationship scale, pearson productmoment correlation coefficient was carried out to check the relationship between being validated variable (brief family relationship scale) and anchor variable (satisfaction with family life scale) and explain its relationship to the validity of the scale being validated. principal factor analysis with a varimax rotation was used to explore the structure underlying the 16 items and construct validity of the scale. the inclusion or exclusion of an item in a construct was determined by examining factor loadings and cronbach alpha to identify whether the scale sufficiently measures the same underlying construct. the inclusion or exclusion of an item in a construct was determined by factor loadings. items with pearson’s correlation coefficient <0.40 were excluded from further analysis following the suggestion of souza et al. (2017) confirmatory factor analysis was carried out to test the factor structures identified in the exploratory factor analysis. the completed data were analyzed using a statistical package for social science (spss) version 24 and (amos) version 24. 3. results in this section, demographic characteristics of the participants and the obtained results are presented respectively based on the specific objectives. 3.1. demographic characteristics of the study participants in the study, a total of 101 (46 males and 55 females) individuals were participated. out of the total participants’, 70.3% of them were married whereas the rest 29.7% of them were single. concerning the ages of participants, from the ages of 20 to 60 was participated. participants who had the educational level of certificate to second degree holders were involved in the study. galata and belay east african journal of sciences volume 16(1): 57–68 62 3.2. reliability of the scales internal consistency measure was applied to estimate reliability indices of the two scales and sub-scales. as indicated in table 1, the internal consistency reliability of the scales and subscales were within the acceptable range. for example, according to griethuijsen et al. (2014) there is no universally agreed rule for determining alpha level as acceptable or not, however, alpha level above 0.60 is acceptable and useful. in support of this notion, mun et al. (2015) argued that, while different scholars have suggested different alpha levels as acceptable, alpha levels greater than 0.60 are acceptable and useful. the same token, excellent reliability (0.90 and above), high reliability (0.70–0.90), moderate reliability (0.50–0.70), and low reliability (0.50 and below) are the four cut-off values proposed by taherdoost (2016). furthermore, hajjar (2018) stated that alpha level between 0.6 and 0.8 is acceptable. though it appears old source, hulin et al. (2001), suggested that the general recommendation of acceptance is α values of 0.60–0.70, while α value of 0.80 or above is a very good level. however, values higher than 0.95 are not necessarily good, since this may be an indication of redundancy. some differences between the original cronbach alpha results and the present obtained results were reported (table 1). this could be attributed to such factors as sample size, nature of participants that participated in the study, situations in which participants fill out the scale others. level of education, motivational factors (existence of a reward for questionnaire completion, relevance of the study for the investigated population, gender of the survey operator); and environmental factors (type of administration, level of noise, intimacy during questionnaire completion) are some of the factors that influence the level of cronback alpha results ursachi et al. (2015). in connection to the present argument, taber (2018) after reviewing different research article on reliability of the scales urged that despite many authors following a rule-of-thumb that alpha should reach 0.70 for an instrument to have an acceptable level of internalconsistency, there are limited grounds for adopting such a heuristic. that is, it is not always the case that an extremely high alpha value is a positive thing. a high value does not necessarily suggest that an instrument or scale is one-dimensional, and in some circumstances, a very high value may indicate inefficient item redundancy. the current instrument validation did not, in fact, end with reliability assessment. exploratory and confirmatory factor analysis was used in addition to cronbach alpha internal consistency reliability test. according to (taherdoost, 2016) to run for exploratory factor analysis, reliability of the scale should be equal to or above = 0.60, which the current obtained reliability of each dimension of the scale was qualified for and recommended for further analysis (i.e., running exploratory and confirmatory factor analysis) which the present researchers did. table 1. internal consistency reliability cronbach alpha results for bfrs, subscales and anchor variable. variables no. of items original cronbach α current cronbach α brief family relationship scale (bfrs) 16 0.88 0.70 • family cohesion 7 0.83 0.86 • expressiveness 3 0.65 0.69 • conflict resolution 6 0.80 0.60 satisfaction with family life (swfl) 5 0.94 to 0.79 0.82 3.3. validity of the scale convergent and discriminant evidence for validity of bfrs were reported below in the table 2. 3.3.1. convergent validity convergent validity of brief family relationship scale was established after examining the relationship between bfrs with an anchor variable, satisfaction with family life scale (swfls) which is also theoretically related constructs with bfrs (devellis, 2003). hence, a statistically significant relationship between bfrs and satisfaction with family life scale (swfls) was achieved (r = 0.187*, p < 0.01). in the same table, a significant relationship between cohesion dimension of brief family relationship scale with an anchor variable i.e., satisfaction with family life scale was reported (r = 0.220**, p < 0.01). in tune with this finding, the factorial galata and belay brief family relationship scale for measuring quality of family relationship 63 loads obtained from exploratory factor analysis for all items of the scale proved that the scale has strong convergent validity where all items have loaded above .40 on the scale. in light with souza et al. (2017) suggestion in which they stated that at convergent validity, the items that indicate a specific construct must have a high proportion of variance in common and high factorial loads indicate that they converge to a common point, that is, there is convergent validity. in tune with souza et al. (2017) suggestion, each item of the present validating scale was loaded more than 0.60 variance on the scale that clearly depicts convergent validity of the scale. 3.3.2. discriminant validity the scale has also high discriminant validity such that the correlation between swfls and family conflict dimension is almost zero (r = 0.004, p > 0.05). table 2. convergent and discriminant evidence for validity of bfrs. variables bfrs expressiveness conflict cohesion swfls bfrs 1 expressiveness 0.379** conflict 0.558** –0.190 cohesion 0.853** 0.134 0.226* swfrs 0.187* 0.085 0.004 0.220** 1 note: * and ** refer to correlation, which is significant at 0.05 and 0.01 probability level (2-tailed), respectively. 3.4. exploratory factor analysis (principal component analysis) exploratory factor analysis was employed to check the underlying structure of bfrs. originally the scale has three dimensions as follows: cohesion with 7 items (in our family we really help and support each other, in our family we spend a lot of time doing things together at home, in our family we work hard at what we do in our home, in our family there is a feeling of togetherness, my family members really support each other, i am proud to be a part of our family, in our family we really get along well with each other). expressiveness with 3 items (in our family we can talk openly in our home, in our family we sometimes tell each other about our personal problems and, in our family, we begin discussions easily) and conflict with reversely coded 6 items (in our family we argue a lot, in our family we are really mad at each other a lot, in our family we lose our tempers a lot, in our family we often put down each other, my family members sometimes are violent and, in our family, we raise our voice when we are mad). the 16 items of the brief family relationship scale (bfrs) were subjected to principal components analysis (pca) using spss version 24. before performing pca, the suitability of data for factor analysis was assessed. inspection of the correlation matrix revealed the presence of many coefficients of 0.30 and above. the kaiser meyer-olkin value was 0.681, exceeding the recommended value of 0.60 (revelle, 2016) and bartlett’s test of sphericity reached statistical significance, supporting the factorability of the correlation matrix. principal components analysis revealed the presence of the following three components with eigenvalues exceeding 1, explaining 22.08%, 16% and 10.50% of the variance, respectively. component 1 (cohesion dimension) involves four items: • in our family, we really help and support each other, • in our family, we spend a lot of time doing things together at home, • in our family, we work hard at what we do in our home, and • in our family, there is a feeling of togetherness. component 2 involves the following ‘expressiveness dimension’ items: • in our family, we can talk openly in our home, • in our family, we sometimes tell each other about our personal problems and • in our family, we begin discussions easily. component 3 involves conflict dimension with six items: • in our family, we lose our tempers a lot, • in our family, we often put down each other, • my family members sometimes are violent, • in our family, we raise our voice when we are mad, • in our family, we argue a lot, and • in our family we are really mad at each other a lot. galata and belay east african journal of sciences volume 16(1): 57-68 64 an inspection of the scree plot revealed a clear break after the third component. using catell’s scree test, it was decided to retain three components for further investigation. the three-component solution explained a total of 48.20% of the variance. confirmatory factor analysis was employed to cross validate the factor structure identified by the exploratory analysis. this analysis was carried out to determine if the factor model identified by the exploratory analysis was a good fit for the hypothesized factor model. the goodness of fit for the competing models was evaluated through fit indices: root mean square error of approximation (rmsea); comparative fit index (cfi); chi-square test, bic and goodness-of-fit index (gfi). the results are presented in table 3. table 3. model fit indexes of first-order confirmatory factor analysis. no of items χ2 (df) bic gfi cfi rmsea 16 1.989 362.399 0.792 0.763 0.099 first round confirmatory factor analysis was made to examine the fitness of the model such that the obtained result was not fit to the existing model suggested by the developer of the brief family relationship scale (bfrs) χ2 (101) = 200.869, χ2/df = 1.989, gfi = 0.792, cfi = 0.763, and rmsea = 0.099. the figure of first round confirmatory analysis presented as follows: figure 1. first order confirmatory factor analysis. as can be seen from the model, originally, the scale has three dimensions such as cohesion (seven items), expressiveness (communication) (three items) and conflict (six items). however, while confirmatory factor analysis was made, the model fails to fit to the originally suggested model. this unfitness of the first-order model gave rise to running for post hoc modification presented (table 4). post hoc modification indices were conducted employing confirmatory factor analysis such that great improvement to fit the existing model was observed χ2 (98) = 144.95, χ2 /df = 1.479, gfi = 0.851, cfi = 0.889, and rmsea = 0.069. rmsea values ranging from 0.05 to 0.08 are indicative of a reasonable fit (maccallum et al., 1996; tabachnick and fidell, 2007). galata and belay brief family relationship scale for measuring quality of family relationship 65 table 4. post hoc modification indexes. no. of items χ2 (df) bic gfi cfi rmsea 16 1.479 320.331 0.851 0.889 0.069 as can be seen from figure 2, to make a model modification, after correlation of three items of the same factor (cohesion) that seems to be redundant in measuring the same construct such as, “my family members really support each other, i am proud to be a part of our family and in our family, we really get along well with each other”, were made, post hoc model modification analysis was found to be reasonably fit. owing to the incompatibility of these three items, they were removed from the scale and following the removal of these three items from the cohesion dimension of the scale, the cronbach alpha result of the factor improved from α 0.79 to 0.86. in a nutshell, the original three subscales of the scale (cohesion, expressiveness, and conflict resolution) are retained in the current adaption process of the brief family relationship scale to our setting, with the exception of the three items retracted from the cohesion dimension of the scale. hence, in the present adaptation, the total obtained cronbach’s alpha result of the scale is α = 0.70 whereas for each dimension of the scale (cohesion (4 items) α = 0.86, expressiveness (3 items) α = 0.69 and conflict resolution (6 items) α = 0.60) were reported and suggested to use in the ethiopian context for the same purpose. the current obtained result may be challenged with new research findings that would be conducted by other interested researchers in the ethiopian context. hence, until the current conclusion is convincingly contested by the results of future study, the three retracted items from the cohesiveness dimension are proposed to be deleted from the scale when collecting data in the ethiopian context while using the scale for the intended purpose. figure 2. post hoc confirmatory factor analysis. 4. discussion it is common in ethiopia that the tools used to measure different family concerns have been developed in english-speaking countries that could influence the effective use of the scales to the ethiopian local context. owing to cultural nonequivalence, some items of the scales may not accurately measure the domains of the construct under consideration. because, in ethiopian context, family psychology is in its infancy stage, validated instrument set to measure family relationship is hardly found. thus, a validated tool designed to measure family relationship is needed. instruments that are aimed to measure family relationship are required to be validated prior to being administered to other populations, while maintaining the context of the original assessment tool. having this information in mind, an attempt was made to adapt brief family relationship scale to the ethiopian galata and belay east african journal of sciences volume 16(1): 57-68 66 context. consequently, in the present study three specific issues were addressed in the validation process: reliability, underlying factor structures, and evidence for validity. adequate internal consistency was found for each of the subscales as well as the overall scale. thus, the obtained result proved that the brief family relationship scale has a reasonable internal consistency with overall cronbach alpha result of (α = 0.70) as well as the three sub-scales of the scale: cohesion (α = 0.86), expressiveness (α = 0.69), and conflict (α = 0.60) in the ethiopian context. in support of the present findings griethuijsen et al. (2014), urged that although there is no universally agreed rule for determining alpha level as acceptable or not, alpha level above 0.60 is acceptable and useful. consistent with griethuijsen his associates’ statement, mun et al., (2015) argued that while different scholars have suggested different alpha levels as acceptable, alpha levels greater than 0.60 are acceptable and useful. with the same token, (paiva et al., 2014) urged scales with internal consistency 0.6-0.7 indicates an acceptable level of reliability, and 0.8 or greater a very good level. furthermore, hajjar (2018) stated that alpha level between 0.6 and 0.8 is acceptable. a high value does not necessarily suggest that an instrument or scale is onedimensional, and in some circumstances, a very high value may indicate inefficient item redundancy. indeed, according to paiva et al. (2014), divergences in internal consistency could be attributed to the influence of cultural and social contexts of participants. alpha level can be fluctuated owing to different factors including, but not limited to, cultural differences, number of items, sample size, psychological readiness of participants while filling out the questionnaire. hence, it is not striking if the alpha level difference between the original instrument and the current validated instrument obtained as there is clear and visible cultural difference between the setting where the instrument was originally developed, alaska, usa and ethiopian cultural context. however, the most important and promising thing is that although slight alpha level difference was reported between the original scale and the present scale, the original dimensions of the scale were maintained in the ethiopian context. that it means, originally the scale has three dimensions (cohesion, expressiveness and conflict) and again in the ethiopian context it maintains its three dimensions as it is. in the present adaptation process of the brief family relationship scale three dimension factors that explained 48.20% of the overall variability in the data was reported. the percentage of explanation of the overall variability was reasonable. after confirmatory factor analysis was employed to cross validate the factor structure identified by the exploratory factor analysis, three items from the initial cohesion dimension of brief family relationship scale were removed. the removed items were; my family members really support each other, i am proud to be a part of our family and in our family, we really get along well with each other. following the removal of the mentioned items from the model, the previously established dimensions of the scale were confirmed. after the elimination of the three items, the present modified model confirmed to the original/ established model of brief family relationship scale developed by (fok et al., 2014). the incompetence of the three items could be attributed to different factors such that cultural and language nonequivalence, poor fitness of the items to non-western context are some of them. in support of the present argument (charalampous et al., 2013) in their attempts to validate family environmental scale in greek culture, they came up with low reliabilities with the conflict dimension of the scale where they stated concerns that some items may not have equivalent meaning across cultures which also hold true for some of the dimensions of brief family relationship scale in the present adaptation process to the ethiopian context. similarly, omar et al. (2010) in their effort to validate family environmental scale in malaysian culture they came to conclude that for all dimensions of the scale cronback alpha result between 0.61–0.70 were reported. this indicates how the scale has also a history of low reliability status in malaysian culture as well. this could be explained such that in the sense that malaysians follow collectivist cultural orientation like ethiopians (nsamanang, 2010), this could be served as a justification for the reason why low cronback alpha score were reported for the some of the dimensions of the scale though the total cronback alpha result of the scale is within acceptable range. 5. conclusion and recommendations this study used statistical analyses and a review of the literature to discover a construct validity of brief family relationship scale (bfrs) in the ethiopian context. the principal findings of this study confirmed that the bfrs is comprised of three sub-factors, with acceptable internal consistency for the full-scale as well as the three subscales: cohesion, expressiveness and conflict. the cohesion dimension of the scale has also a good relationship with anchor variable (i.e., satisfaction with galata and belay brief family relationship scale for measuring quality of family relationship 67 family life scale). convergent and discriminant validity of the sub-factors was demonstrated in the process of adaptation. based on the present study, three items of cohesion dimension such as “my family members really support each other, “i am proud to be a part of our family, and in our family, we really get along well with each other” are proved to be retracted from the original cohesion dimension of the scale through both exploratory and confirmatory factor analysis. after performing a factorial analysis, our findings offer evidence of the validity and reliability of a final 13item to measure the three dimensions of brief family relationship scale (cohesion, expressiveness and conflict). given the psychometric features of the scale, we can deduce that this scale is a valid tool to measure status of family relationship in the ethiopian context. therefore, the scale can be helpful for the research and interventions regarding family relationship affairs in the ethiopian context. this is, therefore, until the present finding proved wrong may be with a large sample size more than the number of samples involved in the present study by other interested researchers, the mentioned three items are suggested to be removed from the cohesion dimension. similar research with a large sample size, inclusive of all age groups, and diversity that entertain the real ethiopia picture need to be conducted to further affirm or disprove the present obtained findings. the validation of the brief family relationship scale is hoped to stimulate the advance of studies in the field of family relationship in the ethiopian context. 6. acknowledgments the authors thank all participants in this 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benishangul-gumuz region of ethiopia ebisa olika keyata1,2*, yetenayet b. tola2, geremew bultosa3, sirawdink fikreyesus forsido2, and assefa gidesa4 1department of food science and nutrition, wollega university, p.o. box 38, shambu, ethiopia 2department of post-harvest management, jimma university, p.o. box: 307, jimma, ethiopia 3department of food science and technology, botswana university of agriculture and natural resources, private bag 0027, gaborone, botswana 4assosa agricultural research center, ethiopian institute of agriculture research, p.o. box 265, assosa, ethiopia abstract background: in ethiopia, particularly in the benishangul-gumuz region, there are numerous underutilized plants like figl (raphanus sativus), girgir (eruca sativa) and karkade (hibiscus sabdariffa) which are cultivated and consumed only by the local communities. however, information on production practices, postharvest handling, and utilization trends of these plants is limited. objective: assess the production, handling, and utilization pattern of figl, girgir, and karkade in the benshangul-gumuz region of ethiopia. methodology: a cross-sectional household survey was used to collect primary data from 274 producers and 30 users using a semi-structured questionnaire. the data were analyzed using spss (version 20.0) software package. results: the results showed that about 46% of farmers produce figl and girgir for food, medicine, and income generation. more than half of the farmers produce karkade for beverage and medicine. about 93% of the respondents showed that, edible parts of figl and girgir could attain commercial maturity within 15– 35 days. however, calyces of karkade takes 121–150 days. most of the farmers consume leaves and roots of figl and leaves of girgir as local salads while 84.31% use dried calyces of karkade for making a beverage. about 94% of the farmers allocated less than 0.25 hectares of land for the production of figl and girgir while 81% of them allocated this amount of land for the production of karkade. the majority (80%) of them are not getting extension services for the production of figl, girgir and karkade, and 53% lament that there is no market linkage for these crops. conclusions: figl and girgir play significant roles in mitigating food insecurity because they reach commercial maturity within a short period and the possibility of cropping about five cycles throughout the year, particularly in marginal lands with agronomic practices accessible to farmers. therefore, future research should incorporate packages of farming technology including propagating the crops at research centers, adaptation trial across different agro-ecology, improving of agronomic practices, variety registration and promotion. keyword: calyces; figl; girgir; karkade; leaves; roots 1. introduction the global population depends entirely on a few staple crops for food, medicine and other associated purposes. even though globally there are a lot of various edible plant species that can be used as fruits, leaves, whole plants, flowers, seeds, pods, tubers, roots, shoots, bulbs, gums, rhizomes, barks and stems (kiran et al., 2019). dependence on a limited number of plant species is not adequate to sustainably feed the rapidly increasing population of the world, which is estimated to reach 10 billion by 2050 (un, 2017). the over-dependence on staple crops coupled with the global population increase exerts pressure on land, water, natural resources and energy for food production to attain food and nutrition security. current crop production levels have decreased due to the lack of investments in agricultural inputs, degradation of natural resources, high postharvest losses, climate change effects, disease, and pest infestations (stathers et al., 2013). ultimately, this has led to food and nutrition insecurity in developing countries. a food system-based intervention that encompasses diversification of food resources has high potential to mailto:ebisaolika20@gmail.com ebisa et al. east african journal of sciences volume 15 (1) 79-94 80 offer an affordable, reliable, and sustainable strategy for promoting food and nutrition security. the promotion of diversified cropping systems in poverty-stricken and drought-prone farmer communities are helpful for the betterment of livelihoods. one way of providing food diversity and supply of relatively less-costly food alternatives is to commercialize the production and utilization of underutilized indigenous plant species. neglected and underutilized plant species further offer an inexpensive source of essential nutrients and bioactive compounds with antioxidant capacity vital for human health and wellbeing (dias and ryder, 2011). underutilized indigenous plant species continue to play an important role in the subsistence and economic resource poor people throughout the developing world, particularly in the agrobiodiversity-rich tropics. despite their potential for dietary diversification and the provision of micronutrients such as vitamins and minerals, they continue to attract little research and development attention. alongside their commercial potential, many of the underused crops also provide important environmental services, as they are adapted to marginal land and climate conditions. the western part of ethiopia, particularly benishangul-gumuz region, is one of the least developed and food insecure hot spots (guyu and muluneh, 2016) but, endowed with many underutilized plants such as figl (raphanussativus l.) and girgir (eruca sativa l.) categorized under vegetable of brassicaceae (cruciferae) family. the karkade (hibiscus sabdariffa l.) is classified under herb of the malvaceae family, in addition to use as foods and beverages, as industrial food color (dye) is underutilized crop in ethiopia (keyata et al., 2021). originally, these underutilized plants come from the border of sudan and their names are derived from arabic sudanese language and named as figl, girgir and karkade in berta, amhara and oromo ethnic groups. the english language name of figl, girgir and karkade are radish, rocket and roselle, respectively. since the benishangul-gumuz region of ethiopia is bordered to the sudan, the cultivation of these vegetables are expanded through this border. currently, these crops are adapted to some parts of benishangul-gumuz region, ethiopia. the 2017 reports of benishangul gumuz regional government of agriculture office highlighted that these plants have unique properties in terms of high climate adaptability, as evidenced by their early commercial maturity and ability to grow and produce high yields in marginal soils (bgrgao, 2017). the report also showed that these plants are tolerant of pests, diseases, and drought incidences as compared to other indigenous plants consumed in the region. furthermore, the report also indicated that the dried calyx of karkade is used to make hot and cold beverages commonly consumed during festival seasons, family, religious celebrations, and medicinal purposes. the leaves of girgir are used as a vegetable whereas the leaves and roots of figl are used in salad or cooked vegetable preparations (keyata et al., 2020). research report from other countries showed that calyces are significant sources of β-carotene, vitamin c, iron, carbohydrates, and fiber (chinatu et al., 2016). the seed of karkade is rich in fats, protein, fiber, calcium, and potassium (keyata et al., 2020). the calyces of karkade have the potential for use as a natural food colorant (shruthi et al., 2016). the girgir leaves are noted for isothiocyanates, flavonoids, antioxidants, calcium, iron, potassium, and sodium (elsadek, 2014). the leaves of figl are significant sources of calcium, vitamin c and phenolic antioxidants (goyeneche et al., 2015). the production practices, post-harvest handling and utilization trends of figl, girgir and karkade are unique in the region because they can be cultivated on marginal lands and are used for food, beverage as traditional medicine and for income generation. due to these properties, the three plants are considered as future plants for climate-smart agriculture to contribute to the food and nutrition security efforts of the country (keyata et al., 2020). it is, therefore, imperative to study and promote the production and consumption of these underutilized plants. due to a lack of sufficient scientific data about the production practices, postharvest handling and utilization trends of the unexploited plants of figl, girgir and karkade the crops are not widely cultivated for consumption in the country. in view of this, in this paper, the documentation on indigenous knowledge on production, postharvest handling and use of the three crops in homosha, kurmuk, and sherkole districts of assosa zone, benishagul gumuz region, ethiopia is reported. finding of this research will contribute knowledge on the many functions/benefits of these crops for consumers, biodiversity conservation, nutritionists, and for the scientific community. the finding will help to create awareness among the scientific community for wider consumption of underutilized edible plants in a versatile way in the recipe development of traditional foods and industrially processed products to contribute to the household and national food security in the country. the policy makers will use the information as an input to develop the crops in the country. 2. materials and methods 2.1. description of the research areas a survey was conducted in homesha, kurmuk, and sherkole districts of assosa zone, benishangul-gumuz regional state, ethiopia (figure 1). assosa zone is located at 10.07°n and 34.53° e, 1417m above sea level, and receives an average annual rainfall of 1316 mm. the area experiences annual minimum and maximum temperatures of 19°c and 35°c (nmsa, 2018). the three districts (homesha, kurmuk, and sherkole) were selected purposely as focus study sites from the seven rural districts of the zone based on more extensive productions and utilization of figl, girgir, and karkade. ebisa et al. production, handling and utilization trends of some neglected plants 81 the total human population in homesha, kurmuk and sherkole districts are 27,616, 21,140 and 31,260, respectively (csa, 2017). the number of households in the homesha, kurmuk and sherkole districts are 3,336, 5,914 and 4,382, respectively (benishangul gumuz regional governmental agricultural office, 2017). data from the district agricultural offices showed that the total households involved in the production of the three plants were estimated 140 in homesha, 350 in kurmuk, and 380 in sherkole. figure 1. map of the research areas. 2.2. sample size determination for users, ten respondents were selected based on a snowball sampling technique from each district of the study area. thirty respondents were also randomly selected as targeted users. however, the total number of producers considered for this study was calculated according to yamane (1967) method with 95% confidence level and ± 5% precision, as shown below. 𝑛 = 𝑁 1 + 𝑁(𝑒)2 = 870 1 + 870(0.05)2 = 274 where, e = precision, n = total number of farmers who produce figl, girgir, and karkade, n = total sample size obtained from total producers. 2.3. research design and sampling techniques a cross-sectional survey was carried out from november 2018 to january 2019 at the selected districts to assess the production, handling, and utilization practices of the underutilized plants. in a multi-stage sampling technique, a specific one was selected purposely based on the production trends of the plants. in the first stage, the snowball sampling technique was used in selecting users who are purchasing and using the edible parts of the crops from the market. in the second stage, a simple random sampling technique was applied to select producers who produce and use the three plants. finally, based on the proportion ratio needed in each district, a random proportional sampling technique was used. 2.4. data collection procedures 2.4.1. individual interview a semi-structured questionnaire was developed to study producers' socio-demographic, production and postharvest handling practices, and utilization trends of the plants. enumerators with fluent in understanding of the local language were selected and trained before data collection. the questionnaire was pre-tested using pilot interviews with producers and users. 2.4.2. focus group discussion a total of three focus group discussions (fgds), each having ten members, were held. producers with extensive expertise in the production, handling, and utilization practices of the three plants were included in the fgds. the discussions were focused on production, post-harvest handling, and utilization procedures. 2.5. data analysis the data were analyzed using simple descriptive statistics (including frequency, mean, and percentage) using spss (version 20.0) software package. ebisa et al. east african journal of sciences volume 15 (1) 79-94 82 3. results and discussions 3.1. socio-demographic characteristics of the participant the socio-demographic characteristics of the participants showed that most of the participants were male and in the age range of 31–60 years. almost half of the respondents had no formal education, and nearly all were married (table 1). table 1. demographic characteristics of respondents who produce figl, girgir and karkade. variable frequency percentage sex male 254 93 female 20 7 age <20 4 2 20-30 23 8 31-40 61 22 41-50 88 32 51-60 72 26 >60 26 10 educational level no formal education 116 42 grade 1–6 132 48 grade 7–12 25 9 college certificate and above 1 0.4 marital status married 254 93 single 7 2 widowed 13 5 family size <3 19 7 3–5 38 14 5–7 67 24 >7 150 55 3.2. production practices in terms of production, about half of the respondents were producing figl and girgir for use as food, medicinal plant, and as an income source (table 2). the studies conducted elsewhere shows that figl is produced for food and medicine (banihani, 2017) whereas girgir is produced for food (siomos and koukounaras, 2007). the findings of this study also indicate that more than half of the respondents use karkade for making beverage and medicine. consistent with these results of this study a study conducted in sudan revealed that karkade is widely cultivated for beverage, medicine, flavoring and as a coloring agent for food and drinks (mohamed et al., 2012). as an underutilized plant, the land allocated for producing figl, girgir, and karkade was small. about 94% of the respondents allocated less than 0.25 ha of land to produce figl and girgir. the size of land allocated for this purpose is lower than the land allocated for the production of cabbage in gurage (0.94ha), hadiya (1.49ha) and west showa zone (3.83ha) of ethiopia (emana et al., 2015). most of the respondents allocated less than 0.25 ha of land for the production of karkade. this finding is somewhat similar to the size of land allocated for the production of karkade, which ranged between 0.04 ha to 3.45 ha (ogunsola et al., 2018). concerning production experience, more than half of the respondents practiced production of both figl and girgir for more than ten years. most of the respondents indicated they produced karkade for more than ten years. farmers in nigeria have more experience (20 and 68 old) with 10 to 54 years of farming of the crop (ogunsola et al., 2018). most of the producers responded that they planted figl and girgir under both rain-fed and irrigation schedules. however, all the farmers reported that they practice the cultivation of karkade only during the rainy seasons. the study conducted in sudan indicated that karkade is grown mainly by traditional farming methods, exclusively under rain-fed conditions (el naim and ahmed, 2010). most of the respondents indicated that they produce figl and girgir from three to five times per year. however, in the focus group discussion, it was indicated that figl and girgir could be produced more than five times per year. all the farmers responded that karkade could be cultivated only once a year during the rainy season. a similar result was reported in the karkade plant elsewhere (ansari et al., 2013). ebisa et al. production, handling and utilization trends of some neglected plants 83 table 2. production of figl, girgir and karkade among surveyed housed hold in the study area. variable n (%) figl and girgir (n = 274) karkade (n = 274) purposes of production food 19(7) food and cash crop 83(30) food and medicine 40(15) food, medicine and cash crop 125(46) food, medicine, cash crop and cultural ceremonies 7(3) beverage and medicine 150(55) beverage, medicine and cash crop 20(7) beverage, medicine and cultural ceremonies 28(10) beverage, medicine, cash and cultural ceremonies 76(28) estimated land allocated for the production <0.25 ha 275(94) 222(81) 0.25 ha 14(5) 48(18) 0.75 ha 3(1) 4(1) production experience 1–3 years 26(9) 17(6) 3–5 years 40(15) 31(11) 5–10 years 61(22) 31(15) >10 years 147(54) 186(68) the production system rain-fed 32(12) 274(100) irrigation 62(23) rain-fed and irrigation 180(66) production frequency 1 274(100) 2 65(24) 3 83(30) 4 51(19) 5 75(27) note: n = frequency. 3.3. challenges of production and marketing concerning the production problems of figl, girgir and karkade (figure 2), most of the farmers indicated that there is no extension service from zone, regional and federal levels during the production of these underutilized plants. in addition to this, the lack of improved varieties and unavailability of seeds were reported to pose problems. the focus group discussion also confirmed that there is no government support regarding the production of the crops. the seed is not readily available like seeds of other staple crops, which are widely cultivated in the study area such as sorghum, maize and groundnut. ebisa et al. east african journal of sciences volume 15 (1) 79-94 84 -40 -20 0 20 40 60 80 100 120 r e sp o n se s (% ) problems during production figure 2. challenges during the production of figl, girgir and karkade among the surveyed households in the study area. regarding the marketing problems of figl, girgir and karkade (figure 3), more than half of the farmers reported that there is no market linkage. furthermore, lack of access to market information, transportation problem and distance from the rural market center were also reported. the results obtained from the focus group discussion also indicated that there is no market linkage across zonal, regional and federal levels. 0 10 20 30 40 50 60 70 r e s p o n s e ( % ) problems during marketing figure 3. challenge during the marketing of figl, girgir and karkade among the surveyed households in the study area. 3.4. harvesting and postharvest handling practices most of the respondents indicated that figl and girgir, attains commercial maturity within 15-35 days (table 3). similarly, a study conducted in romania showed that the leaves of girgir reached commercial maturity within 25 days (varga et al., 2012). in brazil, figl is harvested within three to six weeks (lima et al., 2015). the early commercial maturity in the study area may be associated with the warm weather of the region as compared to other production areas in the country. most of the respondents reported that the commercial maturity for calyces and seeds of karkade were from 121 to 150 days after sowing. in iran, edible parts of karkade were reported to be harvested in 180 days (ansariet al., 2013). the variations in the duration of maturity of the plants may be influenced by plants' genetic difference, agronomic, and climatic differences of the growing areas. the high percentage of the farmers witnessed that the maturity of figl is determined by the color of leaves (dark green) and roots (whitish). similar results were reported for the maturity of roots and leaves of radish grown in korea, when the roots became white while the leaves remained green in color (chandra et al., 2018). similarly, the maturity of the leaves of girgir is determined based on the color and the size of leaves. a study conducted in italy also showed that the leaves of girgir (eruca sativa) reached commercial maturity when ebisa et al. production, handling and utilization trends of some neglected plants 85 the leaves showed a dark or bright green color (mastrandrea et al., 2015). the majority (58%) of the producers asserted that the maturity of calyces and seeds of karkade is determined when the pod becomes dry and open, and then calyx part is separated from the pods and seeds. consistent with this suggestion, castro et al. (2004) highlighted that harvesting calyces of karkade commences when the seed capsules are ready to open, approximately 15–20 days after blossoming. more than half of the respondents indicated that edible parts in figl and girgir are harvested in the morning hours to avoid wilting and withering of the leaves. similarly, reports were documented in korea, where figl harvesting is done in the early morning when the atmospheric conditions are cold (chandra et al., 2018). most of the respondents revealed that calyces and seeds of karkade are harvested any time of the day. however, the results obtained from the focus group discussions (fgds) depict that the harvesting of calyx parts of karkade takes place in the morning to minimizes breakage and shattering losses, which can be incurred due to direct exposure to sunlight. regarding the storage method of edible parts of the three plants, all the respondents showed that there was no storage mechanism for the edible parts of figl and girgir for future utilization. however, respondents from fgds stated that the raw roots of figl could stay two to three days without any deterioration. on the other hand, the fresh leaves are easily spoiled after one day of storage. the leaves of figl and girgir wilt very fast and show changes in coloration from green to yellow, mainly because of the degradation of chlorophyll. lack of adequate cooling facilities reduces the storage potential of the harvest that prompts immediate cooking after harvesting. a study conducted in italy also indicated that after the leaves of girgir were harvested, color changes occurred from dark or bright green into yellow, due to loss of chlorophyll, which leads to yellowing, and a general loss of visual quality (mastrandrea et al., 2015). table 3. post-harvest handling practices of figl, girgir and karkade among surveyed household. variable figl (n = 274) n (%) girgir (n = 274) karkade (n = 274) duration of maturity 15-35 254(93) 255(93) 36-55 20(7) 19(7) 90-120 112(41) 121-150 162(59) determination of maturity edible parts color 120(44) 64(23) 158(58) size 105(38) 130(48) width and length 49(18) 80(29) pod become dry and open 116(42) harvesting methods manual 274(100) 274(100) 274(100) harvesting period of the edible parts anytime 115(42) 115(42.0) 236(86) morning (before noon) 155(57) 155(57) 35(13) afternoon 4(1) 4(1) 3(1) storage of edible parts after harvest home consumption 274(100) 274(100) store sometimes for further use 274(100) packing materials basket 14(5) 14(5) 19(7) plastic 79(29) 79(29) sack 108(39) 108(39) 164(60) basket and sack 73(27) 73(27) 56(20) plastic and sack 35(13) note: n = frequency. calyx of karkade has relatively low moisture content upon harvesting that can favour long-term storage. the data showed that most of the respondents indicated dried calyces of karkade could be stored for seven to twelve months at ambient temperature (figure 4). a response from fgd shows that the dried calyces of karkade can be stored for up to 24 months at room temperature under good storage conditions. the respondents indicated that they store calyx of karkade in anticipation of better market prices and upcoming cultural and religious purposes. similar observations were reported in niger, where calyx of karkade is stored for one to two years with limited insect infestations ebisa et al. east african journal of sciences volume 15 (1) 79-94 86 (boureima et al., 2015). producers also indicated that, after the content is extracted from the calyces of karkade, the product can be kept safe for three to five days at ambient temperature. the delay of the spoilage might be attributed to the presence of antimicrobial and antioxidant agents in the calyces. -10 0 10 20 30 40 50 < 6 month 16 month 7 -12 month 13 18 month 19 24 month r e s p o n s e ( % ) duration of storage figure 4. storage duration of karkade calyces among the surveyed households in the study area. concerning the packaging materials of three plants, most of the respondents use sack bags during transportation of consumable parts of figl and girgir, whereas few of the respondents used both baskets and sacks. the focus group discussion revealed that edible parts of figl and girgir are packed using plastic bags, baskets, and sacks. the packaging materials used for figl and girgir are like the ones used in the northern part of ethiopia to pack leafy vegetables such as cabbage, lettuce, spinach, and swiss chard a basket, plastic materials, and nets (rahielet al., 2018). also, in the studies it was reported that fruits, root and tuber crops were packed in sacks, wooden boxes, and polyethylene bags. most of the respondents used sack bags for the packaging calyces of karkade. in brazil, it was reported calyces of karkade can be packed in glass and polypropylene plastic bags (piovesana and noreña, 2019). more than half of the respondents used human labour to transport figl, girgir, and karkade, and a few of the study participants use both human labour and donkey carts (figure 5). similar results were reported from dire dawa, in the eastern part of ethiopia, where the mode of transport for horticultural crops from farm to temporary storage or the market rely on human labour, donkey, mule, and horse carts, camel, three-wheel vehicle, and trucks (kasso and bekele, 2018). -20 -10 0 10 20 30 40 50 60 70 r e s p o n s e ( % ) means of transportation of three plants figure 5. types of transportation used for figl, girgir and karkade among the surveyed households in the study area. ebisa et al. production, handling and utilization trends of some neglected plants 87 3.5. utilization trends of the plants all (100%) of the respondents indicated that they consume the leaves and root parts of figl, but girgir is preferred for consumption as leaves (table 4 and figure 6). the same was confirmed during fgd with producers of the plants. studies in india also showed that respondents preferred leaf and root parts of figl (dongarwar et al., 2018). in greece, girgir leaves are used in popular dishes to make salad (doulgeraki et al., 2017). figure 6. edible parts of figl and girgir growing in benishangul gumuz region; figl leaves (a), figl roots (b) and girgir leaves (c). a b c ebisa et al. east african journal of sciences volume 15 (1) 79-94 88 figure 7. edible parts of karkade growing in benishangul gumuz region; karkade brown seeds (a), karkade brown red seeds (b), karkade brown calyx (c) and karkade brown red calyx (d). most of the respondents indicated that they used the calyx of karkade to make beverages. some of the producers stated that they used both the calyx and seeds of karkade (figure 7). similar results were reported from indonesia (aryanti et al., 2019). most of the respondents reported that leaves and roots of figl and leaves of figl were used as a source of food and medicine. similar results were reported in china that edible parts of both roots and leaves are used for both food and medicine (dongarwar et al., 2018). most of the respondents used calyces of karkade for beverage, medicinal purposes, and cash crop. the users also confirmed that edible parts of the calyces of karkade are used for a drink on cultural ceremonies (during wedding), new year and religious (mewulid, eid al-fitr and arefa) celebrations, and for medicinal purposes. a report from sudan shows that the dried calyces could be soaked in water to prepare a colorful cold drink or boiled in water for a hot drink or tea (mohamed et al., 2012). the same responses were recorded from both focus group discussions, which indicated that the seeds of karkade are used to make a stew or directly consumed after boiling. the oil content of the seeds could add more flavor and taste to the stew. the seeds of karkade are used for the extraction of edible oils in saudi arabia (shaheen et al., 2012). however, in the study area, some respondents indicated that they used it as an ingredient to make local stew or used it after boiling, but there is no practice of edible oils production indicated. in future, the experience from other countries can be used for the b a c d ebisa et al. production, handling and utilization trends of some neglected plants 89 extraction of edible oils from seeds of karkade in ethiopia. all the respondents indicated that the leaves of figl along with other leaves, roots, tomato and onion by mixing with oil and salts) or in roasted or cooked vegetable form are consumed. besides, the leaves also are cooked together with onion, tomato, beans, groundnut, okra, and meat with the addition of different spices. similar observations were reported from studies conducted in iran, which showed that roots and tender leaves of figl are eaten raw in salads (ghasemian et al., 2016). this report also indicated that edible parts of both leaves and roots could be used in a cooked form and even pickled in brine. most of the respondents use dried calyces of karkade for tea and juice preparation (figure 8). the same result was obtained from the fgd and interview of users. figure 8. traditional tea and juice beverage from calyces of karkade in the benishagul gumuz region; tea (a) and juice (b). the response from users also showed that calyx part of karkade is used by newly delivered pregnant mothers and peoples with cough infections. calyces and seeds part of karkade is an industrial raw material commonly used in different forms for beverages and foods, respectively. the extract from calyces is frequently used in the production of jelly, jam, juice, wine, syrup, gelatin, pudding, cake, ice cream, and flavoring (mohamed et al., 2012). the experiences from other countries are good input to produce a variety of calyces of karkade products in ethiopia. the traditional processing methods of edible parts of the three plants, most of the respondents indicated that they slice and chop the leaves and roots before they mix with a brine solution for 30 min. the prepared slices are consumed with the addition of onion, sliced tomato, and oil. similar practices were reported from iran (ghasemian et al., 2016). however, some of the respondents indicated they use both raw and mildly cooked forms. all the respondents indicated that the same traditional processing methods are used for both hot and cold beverage preparation (table 4). the same was confirmed during fgd with producers and users of the plants. b a ebisa et al. east african journal of sciences volume 15 (1) 79-94 90 table 4. utilization trend of figl, girgir and karkade among surveyed household. variables n (%) figl (n = 274) girgir (n = 274) karkade (n = 274) edible parts roots and leafs 274(100) leafs 274(100) calyx 165(60) calyx and seeds 109(40) uses of edible parts food 43(16) 48(18) food and medicine 118(43) 116(42) food, medicine and cash crop 113(41) 110(40) beverage 82(30) beverage and medicine 75(27) beverage, medicine and cash crop 117(43) food/beverage prepared from edible local salad(leaves+roots+tomato+oil+salt) 274(100) 274(100) cold drink (juice) 13(5) hot drink (tea) 30(11) hot and cold drink 231(84) food/ beverage processing steps from edible parts raw 229(84) 229(84) both raw and blanched (mild heat) 45(16) 45(16) hot drink (tea) (boil the water first and then add boiled water to calyx for few minutes and then filter it and add one or two spoons of sugar to one cup of tea). 274(100) cold drink (juice) (adds the dried calyx into water for one day and filters it. add sugar to make sweet and drink it) 274(100) note: n = frequency. 3.6. medicinal values the traditional medicinal benefits of the three plants are presented in table 5. all the respondents believe that the plants have high medicinal values. respondents indicated that figl could be used to treat abdominal and liver problems, malaria, and typhoid fever and used as an appetizer and cough suppressor. in addition to these, a few of the respondents believe the use of the plants offers a remedy against gastric ulcers, headache and improves blurred eye vision. for girgir, most of the respondents showed that the plant is used to treat malaria and typhoid fever. it cures abdominal and liver associated diseases. some of them believed that the plant is used to treat headache, eye vision, and gastric problems. the study reported from india showed that leaves of figl (raphunus sativus) is the traditionally medicine plant used to treat pain and inflammatory disease. whereas leaves of girgir (eruca sativa) reported from saud arabia have anti-secretory, cytoprotective, and anti-ulcer activities (alqasoumi et al., 2009). most of the respondents believed that karkade calyx of the plant species also helps in preventing anaemia. a few of the study participants indicated that the beverage could be used as an energy drink. contrary to this finding, in indonesia, consumption of roselle (hibiscus) extract combined with iron tablets showed significant increases in haemoglobin levels in pregnant women compared to the use of iron tablets alone. the study conducted in ghana also revealed that hibiscus sabdariffa meal improves women's iron status of child-bearing age with time and is protective of stunting among toddlers during the dry/lean season (kubuga et al., 2019). a study conducted in india showed that drinking beverage made from karkade calyx protects from cold and cough (suresh and ammaan, 2017). this may be attributed to the fact that calyx of karkade consists of vitamin c, which helps to boost the immune system of the body, and facilitates the absorption of iron and thus strengthens the body’s resistance to infection (khalid et al., 2012). anthocyanins and pro-anthocyanidins in the clayx are the two main bioactive compounds that might be responsible for lowering blood pressure (wahabi et al., 2010). ebisa et al. production, handling and utilization trends of some neglected plants 91 table 5. medicinal values of figl, girgir and karkade among surveyed household. variable n (%) figl (n = 274) girgir (n = 274) karkade (n = 274) do you know the medicinal value yes 274(100) 274(100) 274(100) types of diseases treat it abdomen 100(36) 44(16) abdomen and hepatic 74(27) 75(27) abdomen, appetizer and cough 30(11) 20(7) gastric, headache, eye vision 24(9) 41(15) malaria and typhoid fever 46(17) 94(34) anaemia (deficient blood) 249(91) anaemia and energy drink 25(9) edible part used to treat disease leaves 2(1) 274(100) roots 5(2) leaves and roots 267(97) calyx 274(100) dose for male, female, children and adult unknown 274(100) 274(100) 274(100) note: n = frequency. 4. conclusions the potential of underutilized plants figl, girgir and karkade in line with production practices, post-harvest handling and utilization trends towards food and nutrition security in the benishangul gumuz regional state of ethiopia were assessed. the survey result showed that figl and girgir are mainly produced for food, medicine and income generation, while karkade is used for beverage and medicine. the result also indicated that the leave and roots of figl and leaves of girgir reach maturity within one month for household consumption and market purpose. based on this context, the findings imply that figl and girgir can help in mitigating the problems of food and nutritional insecurity mainly because the two crops reach commercial maturity within a short period and can provide more than five cropping cycles throughout the year, particularly in marginal lands with affordable agronomic practices. calyces and seeds of karkade are harvested between four to five months for beverage and local stew preparation, respectively. besides, the seeds of karkade are mostly used by farmers for seedling purposes except in some communities for stew preparation. but the reports in other countries show that the plant seed is a potential source of protein and fat, which is used to complement low energy density to mitigate protein energy malnutrition. these unexploited plants (figl, girgir and karkade) are not widely cultivated for consumption in the country. it could be concluded that these neglected and underutilized species offer the potential to diversify not only the human diet, but also increase food production levels, and, thus, enable more sustainable, resilient agriculture and horticulture-food systems. to exploit the potential of neglected plant species, harmonized attitudes on the national level have to be assimilated that consequently demand the involvement of numerous multi-stakeholders. therefore, stakeholders at different levels should take part in conducting research in agronomy, breeding, protection, ecology and extension activities synergistically in order to boost the production and productivity, handling practices, utilization and commercialization of the three neglected plant species. future research should incorporate packages of farming technology including propagating the crops at research centers and promote their cultivation by farmers in areas where the agro-ecology is suitable. also, it is important to note that these plant species are adapted well in areas with high precipitation and humidity as well as marginal lands. finally, it is required to have strategies to bring neglected plants out of their niche role. thus, development of policies for the promotion of neglected plants and their barriers against mainstreaming of these plants should be primarily well known and then analyzed. 5. acknowledgments authors acknowledge jimma university, college of agriculture and veterinary medicine (jucavm) for financial support. we also thank wollega university and asosa agricultural research center for arrangement logistics during data collection and supports from staffs of the benishangul gumuz region agricultural office. we thank mr. alemayehu oljirra for his support and guidance during the preparation of the research article. ebisa et al. east african journal of sciences volume 15 (1) 79-94 92 6. references alqasoumi, s., al-sohaibani, m., al-howiriny, t., alyahya, m. and 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author: wossen.tarekegne@yahoo.com attribution-noncommercial 4.0 international license. seed system of finger millet [eleusine coracana (l.) gaertn] in yilmana-densa and mecha districts, northwestern ethiopia wossen tarekegne 1*, firew mekbib 2, and yigzaw dessalegn 3 1department of plant sciences, bahir dar university, p.o. box 5501, bahir dar, ethiopia 2school of plant sciences, haramaya university, p.o. box 138, dire dawa, ethiopia 3snv-netherlands development organization, horti-life project, addis ababa, ethiopia abstract background: finger millet is one of the major crops grown in amhara regional state particularly in west gojjam administration zone in maintaining food and nutrition security. however, farmers in the study area grow limited number of finger millet varieties due to inadequate efforts of variety development, seed production, distribution and marketing. objective: the survey was conducted to assess the existing finger millet seed system, variety development, seed production and to suggest options for effective finger millet seed system development. materials and methods: the survey included 120 sample households from four farmers’ associations of yilmana-densa and mecha districts, west gojam zone, northwestern ethiopia. a structured questionnaire was employed to collect primary data through individual interviews and focus group discussions as well as secondary data from relevant organizations and analyzed using spss software version 20. results: the farmers allocate relatively the highest share of their farmland to finger millet. farmers used multiple seed sources, but gift from parents were found to be a predominant seed source at initial time. in both study areas, on-farm saved seeds accounted 83.6 to 88.1% and borrowed or purchased locally seeds accounted 11.9 to 16.4%. this showed the informal seed system accounted 100% of the seeds used, and the use of seed-fertilizer package did not get attention by extension organization. few farmers’ cultivars are grown in the study area due to inefficiency of informal seed system with poor promotion and poor seed quality. conclusion: finger millet producing smallholder farmers have not access to seeds of improved varieties of the crop and informal seed system was inefficient. therefore, it is suggested to strengthen both the formal and informal seed systems to enhance the yield of the crop. keywords: formal seed system; informal seed system; seed production; seed source 1. introduction finger millet (eleusine coracana) is the tropical and subtropical regions crop cultivated in dry areas with limited rainfall and can adapt to different agro-climatic conditions (gull et al., 2014). it is extensively cultivated in semi-arid regions of africa and india and is known to save the lives of poor farmers from starvation at times of extreme drought (kotschi, 2006). one of the important features of millet is its ability to adjust itself to various agro-climatic conditions and serves as a food security crop because it is low input crop and grown mainly by subsistence farmers with high nutritional value and excellent storage qualities (dida et al., 2007). finger millet is a source of dietary fiber, minerals, phenolics and vitamins that have nutritional and health benefits. these substances with nutritional values are found in the outer layer of the grain or the seed coat (antony et al., 1996). the availability of these nutrients can protect against the risk of cardiovascular diseases, type ii diabetes, gastrointestinal cancers and a range of other disorders due to regular consumption of whole grain cereals and their products (mckeown, 2002). however, finger millet in ethiopia does not have history of intensive research and the productivity of the crop is low due to shortage of improved varieties, absence of seed supplying seed companies, poor adoption of improved technologies and local practices dominated cultivation of crop, diseases and moisture stress (degu erenso et al., 2009). modern technology has been the major driving force for increasing agricultural productivity and promoting agriculture development. generation and transfer of improved technologies are a critical prerequisite for https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4033754/#cr4 https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4033754/#cr72 wossen et al. east african journal of sciences volume 15(2): 155-166 156 agricultural development in ethiopia (dawit alemu et al., 2008). enhancing the productivity finger millet requires to utilize improved technologies. in ethiopia, finger millet is considered a minor crop and has received far less research and development recognition than other crops with regard to crop improvement, cultivation practices and utilization as the idea supported by global facilitation unit for underutilized species (2014). the largest producer of finger millet is amhara regional state, which has 53.5, 53.56% and 20.18 kg ha-1 share from national finger millet area, production, and productivity, respectively. west gojam from amhara regional state has a substantially larger shares of 35.21%, 28.97% and 16.61 kg ha–1 area coverage, production and productivity, respectively (csa, 2015). it is used as food and feed crop in west gojam; however, the yield of the crop is low as compared to other cereal crops. this is due to the limited access to improved finger millet varieties and less attention given to agronomic packages in extension services as compared to other cereal crops (wossen tarekegne et al., 2019). dida and devos (2006) also described that the yield of finger millet can reach up to 5 t ha-1, if provided optimal growing condition, but usually, with low emphasis of the crop its productivity is much lower. limited availability and access to improved seeds is regarded as one of the main obstacles to increasing agricultural productivity in ethiopia (ojiewo et al., 2015). improved seed, chemical fertilizers, and extension services to supply the available inputs are important to increase the productivity of crops (araya mebrhatu and sung-kyu, 2019). the sustained increase of crop production and productivity is dependent largely on the development of improved varieties and an efficient seed system for the timely supply of these seeds to farmers (girma abebe and amanuel alemu, 2017). however, limited number of finger millet improved variety coupled with poor seed quality, unavailability of a given variety at the right place, time and required amount; which support with poor extension system observe in the northwest ethiopia. these issues are new point to consider for finger millet and in the northwest ethiopia also. in the other way the farmers’ seed obtained and planted is saved, selected and exchanged among farmers themselves through informal seed system only. however, it is critical to preserving the germplasm and cultivar improvement, it delays the farmers to accessing modern technology for the crop improvement. this implies increasing its productivity by penetrating with application of improved technology to improve the livelihood of the farmers’ is weak through formal seed system; and then all these challenges are hold true to reflect the existence of in efficient seed system of finger millet. therefore, understanding seed system is crucial particularly for crops like finger millet. thus, the objective of this study was to assess the existing finger millet seed system, finger millet varieties used for cultivation, and to suggest effective seed production and supply option in yilmana-densa and mecha districts of west gojam, northwestern ethiopia. 2. materials and methods 2.1. description of the study areas the survey was conducted in two adjacent districts; yilmana-densa and mecha of west gojam zone, northwestern ethiopia. the districts are major finger millet producing and located at about 30 km and 45 km in southwest and southeast of bahir dar city, respectively. rainfall in the areas is bimodal; the short rainy season (belg) in march to april followed by more substantial rainfall between june and september (kremt). during the study period, mecha district received annual rainfall of 1454.5 mm, with maximum and minimum temperatures of 28.1 oc and 9.4 oc, respectively. yilmana-densa district also received an annual rainfall of 1164.1 mm and the maximum and minimum temperatures were 26.9 oc and 10.9 oc, respectively (wamsc, 2013). the geographical descriptions of the experimental area are presented (table 1). table 1. geographical description. location elevation (m.a.s.l.) latitude longitude mecha 1960 11o25’20” n 37o10’20” e adet 2240 11o16’19’’n 37o28’38’’e note: geographical data were organized from berhanu et al., 2014; and nsrc, 2006. 2.2. sampling procedures and participants the study was based on the data that were obtained through a multi-stage sampling technique. three stagesampling techniques were used to select sites and to draw sample farmers. the administrative levels were selected from higher to lower level purposively. first, west gojam zone and two districts were selected on the basic of larger area coverage and production potential through purposive sampling techniques. second, four farmers’ associations were selected purposively based on their potential for finger millet production. third, a total of one hundred twenty finger millet growing farmers were selected based on the list from sample farmers’ associations with random sampling techniques. sample size in each farmer’s association was determined wossen et al. seed system of finger millet in northwestern ethiopia 157 according to the proportion to farmers’ population in each farmer’s associations. in addition, four focus group discussions and individual interviews were conducted using 44-key informants (70.5% males and 29.5% females) who had in depth knowledge about the areas, the farms, crops and local conditions and problems in the farmers’ associations. selection of this group was done in consultation with development agents and a farmers’ associations’ leader who resided in the area and had knowledge of the farmers around. key-informants consisted of male and female, as well as young and old farmers who were growing finger millet varieties. additional information collected from relevant governmental organizations to back up information captured through individual interview and group discussion. 2.3. data collection interview schedule: a questionnaire was designed to gather information on: household characteristics, farmers’ awareness and source of information of new agricultural technologies, farmers’ perception and adoption and diffusion of finger millet varieties, number and types of finger millet varieties, important variety characteristics, seed source and seed selection criteria’s. primary data were collected through focus group discussion and individual interviews on household characteristics (household type, distribution of household by educational status, age, and family size), household resource base characteristics, farmers’ adoption and seed source, farmers’ agronomic practices and perceptions, contractual seed production practices, partners’ involvement and coordination. 2.4. data analysis the data were subjected to statistical analyses using spss (version 21) computer package (ibm, 2012), and relationships were explored through frequencies and descriptive statistics. 3. results 3.1. household socio-economic and land allocation characteristics the result in yilmana-densa and mecha districts among the respondents was found to be 59 and 54 maleheaded households; two and five were female-headed households, respectively. the ratio of male and female family members was close to 1:1 (table 2). the average age of male household members in yilmana-densa and mecha districts was 43.9 (std = 10.5) and 45.04 (std = 8.6) years, respectively. the corresponding value for female household members was 37.5 (std = 3.5) and 46.4 (std = 4.2) years, in the same order. the age of the respondents also ranged from 20 to 66 years at yilmanadensa and 28 to 67 years at mecha districts. nearly half of the total family sizes of sample finger millet producing households in both districts were found to be in the age range below 15 years. the mean number of male and female family members below the age of 15 years in yilmana-densa was found to be 1.34 (std = 1.05) and 1.12 (std = 0.82), respectively. the corresponding values for mecha district was 1.48 (std = 1.18) and 1.56 (std = 1.12) respectively. in contrast, the average number of male and female family members who were above 15 years old in yilmana-densa district were 1.75 (std = 1.07) and 1.54 (std = 0.87) while in mecha district 1.76 (std = 1.07) and 1.78 (std = 0.74), respectively (table 2). both male and female family members in this age range were found to be actively involved in crop production. the contribution of family members even in this age group to farm work and cattle herding is not negligible. among the respondents, 36.1% and 52.5% were found to be illiterate in yilmana-densa and mecha districts, respectively (table 2). this indicated the presence of variation in education level between study areas and large number of farmers who cannot read and write. education improves access to information and raises the capacity to understand agricultural instructions provided by extension workers. hence, it is expected to determine the level of technology adoption. some studies have found evidence that support this prediction (rahman, 2008; hassen beshir et al., 2012). the area of farmland allocated for finger millet production as compared to other crops ranked first at mecha and third at yilmana-densa districts. the average finger millet production farmland sizes per household were 0.26 ± 0.098 ha and 0.54 ± 0.25 ha in yilmana-densa and mecha districts, respectively. the average farmland sizes owned by the farmers were 1.2 ha in yilmana-densa and 1.24 ha in mecha. farmers who grew cereal crops ploughed their land using oxen only. farmers, who do not have oxen, cultivated their land by hiring some from neighboring farmers who did have oxen or would rent out their farmland. the types of livestock found are cows, calves, heifers, bulls, sheep, goats, donkeys, horses, and mules. sample farmers of yilmana-densa and mecha districts owned on average 9 (std 4.6) and 7.6 (std 7.1) heads of livestock. the number of oxen owned were 1.9 (std 0.7) and 1.93 (std 1.03), respectively (table 2). wossen et al. east african journal of sciences volume 15(2): 155-166 158 table 2. household socio-economic and land allocation characteristics of respondent’s farmers in 2013 main cropping season in mecha and yilmana-densa districts. variable mecha district yilmana-densa district number mean % sd number mean % sd number of respondents 59 61 mhh head 54 45.04 91.5 8.6 59 43.9 96.7 10.5 fhh head 5 46.4 8.5 4.2 2 37.5 3.3 3.5 hh size males (>15 years) 104 1.76 26.8 1.07 107 1.75 30.5 1.07 hh size females (>15 years) 105 1.78 27.1 0.74 94 1.54 26.8 0.87 hh size males (< 15 years) 87 1.48 22.4 1.18 82 1.34 23.3 1.05 hh size females (<15 years) 92 1.56 23.7 1.12 68 1.12 19.4 0.82 total family size 388 6.58 100 1.66 351 5.75 100 1.73 respondents age range 20 – 66 – – 61 100 28 – 67 59 100 – – education read & write 2 3.4 3 5 grade 1–4 10 17 10 16.4 grade 5–8 1 1.7 1 1.6 above 1 1.7 1 1.6 illiterate 31 52.5 22 36.1 land holding (ha) < 1 15 25.5 19 31.1 1 to 2 39 66 38 62.3 > 2 5 8.5 4 6.6 average land holding (ha) 1.24 0.62 1.2 0.57 average land area rent (ha) 0.49 0.5 0.57 0.54 average finger millet (ha) 0.54 0.25 0.26 0.098 oxen ownership hh–1 1.93 1.03 1.9 0.7 cattle ownership hh–1 7.6 7.1 9 4.6 household oxen ownership 0 5 8.5 1 1.6 1 11 18.6 14 23 2 32 54.2 36 59 3 6 10.2 10 16.4 4 4 6.8 – – 5 1 1.7 – – total 59 100 61 100 note: mhh = male household; fhh = female household; hh = household; and std = standard deviation. 3.2. farmers’ selection criteria for adopting finger millet cultivars cultivars grown by the farmers during the time of study were, angedi, abate necho, abate tikur, tikur dekie and nech dekie. of all the criteria, most respondents selected cultivars based on seed yield, food quality, early maturity, marketability, thresh-ability and disease resistance. angedi is the most preferred cultivar by farmers for yield and grain color for making injera; medium for brew quality, marketability, lodging and disease resistance; but less preferred for biomass quality, to poor soil fertility (ability to grow on soil with low inherent fertility), thresh-ability and early maturity. abate necho is preferred for food quality (injera making), marketability (seed color), seed yield, making a brew; and less for other criteria. however, more farmers preferred abate tikur for food quality (injera and brew) and yield; medium required for biomass quality, marketability, disease and lodging resistance; but less preferred or thresh-ability and early maturity. the above three local cultivars were grown in both study areas. but at mecha farmers additionally grew widely other local landraces namely tikur and nech dekie but small number of farmers in yilmana-densa district grew tikur dekie. tikur dekie was uniquely appreciated by farmers because of its high yield, good food and biomass quality, marketability, early maturity, thresh-ability and grow the on low soil fertility, disease resistance and lodging tolerance. however, the variety was noted to be low in biomass yield and less preferred for seed color. nech dekie was not widely grown and popular, though it was rated as high in seed yield, seed color, marketability, wossen et al. seed system of finger millet in northwestern ethiopia 159 early maturity and food quality (injera and bread), but it was found to be less preferred for brew making and disease resistance. more than 80% of farmers in yilmana-densa district selected abate tikur. in mecha district, more than 78% of farmers selected tikur dekie, tikur dekie, and nech dekie, which are early maturing and appropriate for late sowing, and they are replaced by abate tikur, angedi and abate necho when there were early onset and enough rainfall. the second selected crop is abate tikur as compared to other cultivars in all selection criteria except marketability, for which abate necho is preferred (table 3). table 3. selection criteria of farmers for finger millet cultivars in 2013 main cropping season in yilmana-densa and mecha districts. selection criteria angedi % abte tikur % abte ncho % tikur deki % nech deki % yd mecha yd mecha yd mecha yd mecha yd mecha seed yield 24.6 22.0 80.3 39 4.9 23.7 4.9 86.4 – 3.4 ingera 27.9 37.3 91.8 67.8 6.6 40.7 4.9 89.8 – 5.1 brew (local) 19.7 11.9 91.8 66.1 1.6 8.5 4.9 91.5 – – bread 23.0 23.7 91.8 66.1 3.3 27.1 4.9 89.8 – 3.4 marketability 11.5 20.3 39.3 28.8 6.6 39.0 4.9 50.8 – 5.1 early maturity 3.3 – 19.6 3.4 – 1.7 3.3 89.8 – 1.7 thresh ability 4.9 – 6.6 8.5 – 3.4 4.9 78.0 – – disease resistance 11.5 3.4 29.5 23.7 – 8.5 4.9 59.3 – 1.7 poor fertility tolerance – 1.7 24.6 1.7 – 1.7 – 37.3 – – lodging tolerance 19.7 5.1 26.2 11.9 – 6.8 4.9 45.8 – – stover – – 14.8 5.1 – – – 15.3 – – note: yd = yilmana-densa. until 2013, sixteen improved finger millet varieties were released by agricultural research institutes in the country; among them, two varieties were released in adet agricultural research center. table 4. description of finger millet varieties released in adet agricultural research center at survey period in 2013 main cropping season. s/n variety year of release seed color maintainer center 1 degu 2005 black adarc/arari 2 necho 2011 white adarc/arari note: adarc = adet agricultural research center; and arari = amhara region agricultural research institute. 3.3. seed sources, purchasing and exchange seed of finger millet the farm-saved varieties obtained by the sampled farmers during the initial time of sourcing the seed was largely found from parents, but later they used their own stock and later purchased certain amounts of seeds from other farmers in the market. farmers’ seed source of finger millet was initially obtained as a gift from parents and later dominated by own seed stock. the norms that have existed for long in the society has contributed to serve as a seed source because parents provide seed for their daughters/sons when they start life independently. exchange for better seed is common to all farmers, but no one requests seed freely in the study areas as the requester could be regarded as lazy. the main advantage of farmers’ uses of their own stock/saving seed were on availability and convenience, quality, save money to buy seed during sowing time, to maintain preferred varieties and increase confidence in abundance of seed at planting time. parents, neighbors, relatives and market were the sources of seed and purchase (farmers, traders); exchange (exchange of labor and other seed), gift and loan are the bases of seed flow. in the context of both study areas, the informal system was only important for the bulk of the seed supply. the seed used by smallholder farmers are shown at decreasing and increasing order at yilmana-densa and mecha, respectively, from our data source (table 5). therefore, the informal seed system accounts for 100% of the seed used during the survey period. finger millet seed flow happens both within and outside the village. farmers use different seed sources for reasons of crop loss, unfavorable weather, to obtain other/new varieties. except those few farmers who received seed from organizations for the demonstration purpose, there is no formal finger millet supply system in the study areas wossen et al. east african journal of sciences volume 15(2): 155-166 160 (table 5 and table 6). the survey result on the major initial sources of seed illustrated that farmers obtained seed as a gift from parents (78.7%) and purchase from farmers (18%) in yilmana-densa and correspondingly in mecha (81.4%) and (10.2%) gift from parents and purchase, respectively (table 5). about 88.5% and 83.6% respondents of yilmana-densa district used own seed stock during 2012 and 2013, respectively, and 76.3% and 88.1% respondents of mecha district used own seed stock in 2012 and 2013, respectively (table 5). table 5. initial finger millet seed source during the 2012–2013 cropping seasons for farmers’ in yilmana-densa and mecha districts. seed source yilmana-densa mecha is 2012 2013 is 2012 2013 n % n % n % n % n % n % purchase from farmer 11 18 7 11.5 10 16.4 6 10.2 8 13.6 7 11.9 gift from parents 48 78.7 0 0 0 0 48 81.4 0 0 0 0 own stock 0 0 54 88.5 51 83.6 0 0 45 76.3 52 88.1 others 2 3.3 0 0 0 0 5 8.4 6 10.1 0 0 total 61 61 61 59 59 59 note: is = initial source; and n = number of farmers. number of farmers involved for purchased and exchanged seeds of finger millet for reasons of absence of own stock seed, replace old seed and to obtain better quality seed at increasing order in both yilmana-densa and mecha districts (table 6). only very small portion of farmers in both districts purchased seed due to absence of own stock seed. about 96.2% and 90.9% farmers, in yilmana-densa replace their seed in average after three years by purchasing and exchange, respectively. similarly, about 74.3% and 80.2% numbers in mecha district renewed their seed after three years in the same order. large number of farmers, about 80.8% and 91.4% buy local cultivar with market distance located less than 11 km radius for yilmana-densa and mecha districts, respectively. table 6. purchasing and exchange reason for local source seed by sample farmers in 2013 main cropping season in yilmana-densa and mecha districts. reason for yilmana densa mecha reasons for yilmana densa mecha purchasing exchange finger millet seed n % n % finger millet seed n % n % replace old variety 9 17.3 8 22.9 replace old variety 4 9.1 9 17.6 better seed quality 39 75 24 68.5 better seed quality 35 79.5 41 80.4 no own seed 4 7.7 3 8.6 no own seed 5 11.4 1 2 frequency seed frequency of purchase exchange of seed every year 0 0 4 11.4 every year 0 0 3 6 every other year 1 1.9 1 2.9 every other year 0 0 1 2 every 3/more year 50 96.2 26 74.3 every3/more years 40 90.9 41 80.2 first time 1 1.9 4 11.4 first time 4 9.1 6 11.8 distance to buy seed 1 to 4 km 22 42.3 17 48.6 5 to 10 km 20 38.5 15 42.8 11 to 15 km 10 19.2 3 8.6 note: farmers may use two alternatives. wossen et al. seed system of finger millet in northwestern ethiopia 161 3.4. source of information and agronomic practices for finger millet production farmers used different sources of information, among them formal extension system has been considered as main source of information and followed by from other farmers’ in both study areas. the most important institutional factor identified to obtain information on availability of agronomic packages was agricultural extension in bureau of agriculture. the data shown 100% of the respondents have access to information on availability of fertilizers and herbicides at both locations as compared to pesticide, storage and agronomy practices (table 7). table 7. farmers’ sources of information for agronomic packages for local finger millet production (n = 120) in 2013 main cropping season in yilmana-densa and mecha districts. sources of fertilizer (%) herbicide (%) pesticide (%) storage (%) agronomy %) information yd mecha yd mecha yd mecha yd mecha yd mecha boa 78.1 80.3 77.8 81.2 40 76.6 0.0 3.1 3.3 5.0 relatives/friends 4.2 1.4 4.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 neighbors 0.0 5.6 0.0 7.2 0.0 0.0 0.0 2.0 0.0 6.9 farmers’ 16.5 9.9 13.8 8.7 0.0 7.8 0.0 0.0 0.0 5.0 traders 1.2 0.0 4.2 0.0 0.0 0.0 3.3 0.0 0.0 0.0 local leaders 0.0 2.8 0.0 2.9 0.0 2.0 0.0 0.0 0.0 0.0 note: boa = bureau of agriculture; yd = yilmana-densa; and same farmers practiced more than one response. land preparation is undertaken using oxen in the study areas. the land plough frequency, such as three, four and five times coincide at increasing order with the number farmers involved in both yilmana-densa and mecha districts (table 8). most farmers plough their farmland five times for finger millet production. the seed rate utilized by farmers’ can be grouped into three as 15, 25 to 50 and 51 to 75 kg ha–1. about 75.4% and 100% of the respondents in yilmana-densa and mecha districts, respectively, used seed rate above the recommendation (15 kg ha–1). the majority (> 50%) of farmers used broadcasting of 25 to 50 kg ha–1 seed rate (table 8). table 8. agronomic practices used for finger millet production in 2013 main cropping season in yilmana-densa and mecha districts. agronomic practice yilmana-densa mecha fertilizer type and rate yilmana-densa mecha n % n % n % n % time of plow artificial fertilizer use three time 7 11.5 0 0 yes 61 100 59 100 four time 17 27.9 7 11.9 no 0 0 0 0 five time 29 47.5 40 67.8 compost above five 8 13.1 12 20.3 yes 4 6.6 3 5.1 seed rate kg ha–1 no 57 93.4 56 94.9 15 15 24.6 0 0 dap kg ha–1 25–50 31 50.8 34 57.6 50 1 1.6 0 0 51–75 15 24.6 25 42.4 100 31 50.8 20 33.9 row planting 0 0 0 0 150 1 1.6 8 13.6 broadcast 61 100 59 100 200 28 45.9 31 52.5 soil fertility status urea kg ha–1 good 5 8.2 8 13.6 25 0 0 1 1.7 medium 33 54.1 30 50.8 50 31 50.8 18 30.5 poor 23 37.7 21 35.6 100 4 6.6 4 6.8 total 35 58.4 23 39.0 note: n = number of farmers’. all of the farmers’ in both districts applied dap, but only 58.4% and 39.0% farmers in yilmana-densa and mecha applied urea, respectively. only about 6.6% in yilmana-densa and 5.1% in mecha districts applied compost. about 50.8% in yilmana-densa and 30.5% in mecha districts, farmers have used the recommended fertilizer rates of dap 100 kg ha–1 and urea 50 kg ha–1; wossen et al. east african journal of sciences volume 15(2): 155-166 162 however, the remaining farmers used fertilizer above the recommended rates (table 8). 3.5. farmers’ contractual seed production as per the key informants and focus group discussion, the contractual seed production (csp) on finger millet was not implemented. however, all interviewed farmers showed interest to participate in contractual seed production in finger millet except some due to shortage of land. in mecha district particularly in the sampled peasant association there was no contractual seed production, but 64.4% of the sample farmers showed interest to participate in contractual seed production due to information obtained in the nearest peasant association. however, at yilmana-densa district, 98.4% of farmers showed interest to participate in contractual seed production since some farmers participate in tef seed production others observed the field during field visit. farmers has shown an interest in contractual seed production to obtain improved input, higher yield, good quality seed, training and higher selling price (table 9). table 9. farmers’ contractual seed production in 2013 main cropping season in yilmana-densa and mecha districts. csp yd mecha csp yd mecha n % n % n % n % farmers liked to 60 98.4 38 64.4 reasons for participation have csp better input 47 77 26 44.1 farmers do not 1 1.6 21 35.6 higher yield 52 85.2 36 61 like to have csp good quality seed 47 77 27 45.8 total 61 100 59 100 training 28 45.9 2 3.4 higher selling price 49 80.3 18 30.5 reasons for not participation shortage of land 1 1.6 11 18.6 un exposure to see csp 0 0 1 1.7 shortage of labor 0 0 3 5.1 no suitable land 0 0 6 10.2 note: csp = contractual seed production; and yd = yilmana-densa. 3.6. partners involvement and linkage public institutions and individuals which have been involved in crop production extension service, technology generation and seed multiplication and supply are amhara region bureau of agriculture and rural development offices at different levels, adet agricultural research center, ethiopian seed enterprise, amhara region seed enterprise, amhara region seed agency, and farmers’. the above institutions and farmers were involved at different level during focus group discussion and interviewee. 3.6.1. agriculture offices and research center bureau of agriculture and rural development has different departments that are responsible for production, quality control and marketing of seed produced by farmers. bureau of agriculture and rural development support farmers based on seed multiplication activity. however, except the major cereal crops, finger millet did not get attention by government in providing improved varieties, promotion work, even though the crop has been grown in wide agro-ecologies and has important role for food security in the region. development agents are providing technical support to the farmers based on present croppackages. there are manuals prepared for cereal seed production, which contain guidelines from seed production to distribution. however, there was no finger millet package like other crops at hand of the development agents to guide improved production. adet agricultural research center is one of the research centers in the amhara region agricultural research institute and working on in the improvement of cereal, pulse and horticultural crops. the center has developed a number of finger millet varieties through selection. however, these varieties did not reach to farmers mainly due to low effort of promotion and scale up work of the center and the extension institutions. 3.6.2. seed enterprises and farmers the formal sectors play minor roles in supplying finger millet seed. the parastatal ethiopian seed enterprise only produces a limited amount of finger millet seed previously. the formal system is now ceased because of poor extension and promotion system in improvement, seed multiplication, distribution and marketing. the stakeholders have very weak linkage in doing their responsibilities. amhara region seed enterprise was participated in multiplication of finger millet seed, in limited area of land, but because of low attention by extension organization to reach farmers; and sale it as grain for wossen et al. seed system of finger millet in northwestern ethiopia 163 consumption. the formal sector is not functioning due to absence of coordination in stakeholders. amhara region seed agency has not multiplied finger millet seed and has not information on farmers’ demand and availability of basic seeds. this formal sector needs promotion work that could be undertaken in an organized manner to access and ensure availability of improved varieties to increase productivity of finger millet. during individual interview and focus group discussion, farmers in four peasant association have reported the importance of improved varieties and use certified seed of maize and tef. they have also mentioned the storage problem of maize compared to finger millet. especially farmers in mecha district reported the superiority of finger millet over other crops in terms of its tolerance to drought and risk minimizing capacity, long life in storage, use of its straw for animal feed and its medicinal value. they finally stated that “you people living in a town have interest on crops like tef, maize and wheat white crops, and do not give enough attention to crops which are very important to us (farmers) such as finger millet “dagusa yehele-anbesa”. 4. discussion sex, age, family size and education level were the factors, which influenced the status and intensity of seed system of finger millet. male-headed households predominantly produced finger millet. the age of most household heads were within the age range considered as productive ages. the national average of 4.6 persons per household (edhs, 2012; csa, 2017) was also lower than the average family sizes of the study areas. all age groups of farmers (young and old) were generally involved in most of the farming activities. this indicated the presence of enough family labor that contributed to farm operations. the education level between study areas had variation and there are large numbers of farmers who cannot read and write. education improves access to information and for the capacity to understand agricultural instructions provided by the extension workers. hence, it is expected to determine the level of technology adoption to give emphasis to establish elder school by government. this result is consistent to findings of (hassen beshir et al., 2012; takahashi et al., 2020). farmland allocated was large for finger millet from farmer land holding as compare to other crops, but they are found in low productivity. according to oduori and kanyeji (2007), girma abebe and amanuel alemu (2017) finger millet production and productivity increase when work should be done on the availability of improved seed, improved extension services, establish efficient system for the timely supply of these seeds. the amount of land owned by the farmers’ had a positive effect on the extent of crop diversification. this implies that relative large farm size in an area may enable households to allot their land for multiple crops, thereby, minimize production costs and risks than small land holders. this result supports by the finding of (wondimagegn mesfin et al., 2011; rehima mussema et al., 2013; abebe birara et al., 2019). farm animals are a source of draught power, means of transport, food and cash, in the study areas. animal dung is used as organic fertilizer and fuel. animals also serve as a measure of wealth in rural areas, but now a day grazing lands changed to cultivated land. among farm animals, oxen are the main draught power sources in the study areas. similarly, solomon asfaw et al. (2011), hassen beshir et al. (2012) and melesse birhanu (2018) indicated that livestock holding plays important role in the decision of farmers to use improved technology. the supply of improved varieties of finger millet was not practiced in the study areas though improved technologies and efficient seed production and supply system is vital to bring change on the livelihood of smallholder farmers. no attempt was made in participated farmers in plant breeding in the process of variety improvements. altaye sisaye (2012) mentioned that researcher’s contribution to technology development with involvement of farmers on finger millet is low. hence, development of varieties without considering farmers’ preferences of traits, are also considered the main reason for farmers to use and grow the landraces up to present time. most respondents’ selection criteria for available cultivars were in agreement with varietal choice on finger millet (wossen tarekegne et al., 2019). farmers replaced one cultivar with other cultivars, such as, tikur and nech dekie in mecha district due to the perception of better return. in addition, farmers’ preferences for different traits have decisive role on varietal composition and diversity. about 100% of finger millet production comes from only local cultivars, and also farmers themselves have domesticated, selected and grown till now the cultivars for their adaptation to heterogeneous soil type, rain fall period, time of planting and productivity. this is due to poor promotion of extension service and in efficient seed system. temesgen teressa (2019) also reported on unavailability of improved seeds at a required period and place with weak extension and seed system. finger millet was produced from farm-saved seeds of farmer’s cultivars in the study areas. this is because that modern seed production and supply system in the country has focused mainly on few crops such as maize and wheat varieties (abebe atilaw and lijalem korbu, 2011; dawit tsegaye et al., 2017). in addition, ojiewo et al. (2015) revealed that as one of the main obstacles in ethiopia for increasing agricultural productivity is limited availability and access to quality seed. the demand assessment is also made without considering the environment, social acceptance and economic benefit of wossen et al. east african journal of sciences volume 15(2): 155-166 164 crops to smallholder farmers. as a result, farmers merely depend on farm-saved seeds of farmers’ cultivars, which are genetically heterogeneous and low productivity. in agreement with this study finding, firew mekbib (2007) on sorghum in eastern ethiopia and melkam anteneh and firew mekbib (2013) on tef in east gojam, amhara regional state reported that farmers produced from farm-saved seeds of farmers cultivars. in contrary to our result, in kenya about three-quarters of survey, farmers obtain quality seed for finger millet production from both private and public sectors supply whereas the remained finger millet producing farmers utilized their own saved seed of local varieties (acet and kirdi, 2014). in the study areas, proximity to market center becomes easier to the farmers to take the products to market and to diversify the choice of farmers. this findings matches that of sichoongwe et al. (2014) who also discovered that presence of output market access have impact of crop diversification, which is intended to give a wider choice in the production of a variety of crops in a given area. however, only very small portion of farmers in both districts purchased seed of local cultivar due to absence of own stock seed, which indicated lack of improved seed cultivars demanded in the market. the recommended seeding rate of finger millet is 15 kg ha–1 as cited by (molla fentie, 2012), though, the farmers have been using more seed rates due to their perception using such high seed rates would help to cope up with environmental uncertainties such as germination problem, weed competition and pest damage at seedling stage. thus, high seeding rates improve the chance of even crop establishment stand under farmer’s conditions. similar to the present study, shinggu et al. (2009) reported that, millet suppressed weed when planted at spacing of 10 cm and 25 cm of between plants and rows, respectively, with 30 kg ha–1 seeding rates. these showed that farmers, researchers, and extension agents’ mechanism of exchange of knowledge and information, feedback on agricultural innovations and activities of surveys and joint adaptive trials were found to be at minimal. similarly, altaye sisaye (2012) reported that research and development in finger millet obtained less emphasis for generating and adoption of improved technologies. farmers have used the same to the recommended fertilizers application of dap at rate of 100 kg ha–1 and 50 kg ha–1 of urea as cited by (molla fentie, 2012) and also different fertilizer rates. this difference in rates of fertilizers application might be the absence of sitespecific fertilizers rates recommendation for the crop, farmers’ decision and financial resource. likewise, in ethiopia there have been attempts made by the government and non-government organizations to promote quality seed production and distribution through market channels, although until now they represent limited availability of and access to quality seed, and which, become as one of the main obstacles to increasing agricultural productivity (ojiewo et al., 2015). the contribution of these actors in finger millet production and seed system is very limited, even though the crop has been grown in wide agro-ecologies without season bound if moisture is available and has important role for nutrition, health benefit and food security in the region. therefore, to improve the existing dysfunctional seed systems an integration of both informal and formal seed systems is vital for the productivity of finger millet. 5. conclusion the results of this study demonstrated that the numbers of farmers’ cultivars grown in the study areas were low due to inefficiency of informal seed system coupled with poor promotion system. farmers kept these cultivars for production due to their taste, tolerance to most biotic and abiotic stresses, adaptability and stability of yield. one key and significant observation was that no improved variety of finger millet was available during the assessment period of the informal seed system; but farmers demanded high yielding improved varieties, mainly with their preferred traits (early maturity, food quality, seed yield, disease resistance, marketability and biomass yield and quality). the results of the study also showed that millet is cultivated totally for home consumption as a subsistence crop, though it has potential to grow as a commercial crop. the use of heterogeneous farmers’ cultivars without application of improved agronomic practices, extension services and efficient seed system could not allow farmers to produce enough to meet their seed demands. as a result, farmers are gradually shifting to grow high yield but nontraditional crops such as maize in the study areas. this indicates that the need of integrated work by component of seed system in variety development, seed multiplication, distribution and promotion. 6. acknowledgements the authors thank the ministry of science and higher education of federal democratic republic of ethiopia and debre markos university for their financial support; and farmers, regional bureaus of agriculture and rural development, amhara region seed agency, amhara seed enterprise, ethiopian seed enterprise, adet agricultural research center and development agents at farmer association for providing primary and secondary information. we would like also to thank fithe-amlak wossen and other data collectors for their unreserved cooperation during the survey periods. https://www.tandfonline.com/doi/full/10.1080/15427528.2017.1303800 wossen et al. seed system of finger millet in northwestern ethiopia 165 7. references abebe atilaw and lijalem korbu. 2011. recent development of seed systems of ethiopia. pp. 13–30. in: dawit, a., kiyoshi, s. and abebe, k. 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trend and determinants of crop diversification: empirical evidence from smallholders in eastern ethiopia. journal of economics and sustainable development, 2(8): 78–89. wossen tarekegne, firew mekbib and yigzaw dessalegn. 2019. performance and participatory variety evaluation of finger millet [eleusine coracana (l.) gaertn] varieties in west gojam zone, northwest ethiopia. east african journal of sciences, 13(1): 27–38. https://onlinelibrary.wiley.com/action/dosearch?contribauthorstored=takahashi%2c+kazushi ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15(2): 129-140 licensed under a creative commons *corresponding author. e-mail: sarashikur2006@gmail.com attribution-noncommercial 4.0 international license. factors affecting choice of livelihood strategies in peri-urban communities of hossana town, southern ethiopia sara shikur1*, jema haji2, and tekle leza1 1department of rural development and agricultural extension, wolaita sodo university, ethiopia 2school of agricultural economics and agri-business, haramaya university, ethiopia abstract background: in ethiopia, the land allocated for urban expansion is taken from farming communities residing in the peripheries of towns and cities. therefore, this decision strongly affects the livelihood of local communities living at peri-urban areas. objective: the purpose of this study was to identify the livelihood strategy choices in peri-urban communities of hossana town, hadiya zone, southern ethiopia and factors affecting them. materials and methods: a household survey research design was conducted using a semi-structured questionnaire by interviewing 369 households. qualitative and quantitative data were collected from primary and secondary sources. in addition to household interview, focus group discussion, key informant interview, transect walk and personal observation were used as data collection tools. the study employed multivariate probit model to identify factors affecting choice of livelihood strategies in peri-urban local communities. results: model results showed that dependency ratio, active labor force in the family, sex of household head, educational levels of household heads, annual total income, market distance, household asset ownership, mass media exposure, achievement motivation, information seeking behavior, distance to public transport, total cultivated land, livestock (other than ox) and extension contact significantly affected choice of livelihood strategies. conclusion: from the results we can conclude that agriculture, cottage/small scale industries, service, migration and other livelihood strategies are used as sources of income in peri-urban communities of hossana town and are affected by different socio-economic, demographic, institutional, information and psychological factors. therefore, it is necessary to give attention to those factors which positively affect agriculture, cottage/small scale industries and service and negatively affect migration and other livelihood strategies. keywords: cottage/small scale industry; migration; multivariate probit; other livelihood strategies; service 1. introduction urban regions worldwide are increasingly facing the challenge of dealing with highly dynamic metropolitan growth and, at the same time, institutional changes like decentralization and globalization. these kinds of changes express themselves most evidently in peri-urban areas, where urban and rural lives meet. these peri-urban areas in particular have been the stage for rapid physical, social and economic transformations, both in developed and developing countries (woltjer, 2014). theoretically a peri-urban interface has been highlighted as lying midway between the urban and the rural areas, practically it is difficult to designate the areas. it is a complex region in itself, being transitional in nature and characterized by neglect, especially in the developing countries. being neither urban nor completely rural, it falls beyond the purview of planners on either side, but continues to host the spill-over population from the urban vicinity, albeit without necessary infrastructural support. land in the peri-urban interface is critically important as the region is impacted by a lack of clarity in land use planning and policies, while being a part of the city’s hinterland, which has its typical economic as well as ecological role in the sustenance of both the urban and rural zones (sarkar and bandyopadhyay, 2013). peri-urban areas in ethiopia, like that of other african countries, are places where much of urban growth is taking place and new urban built-up properties have been formed rapidly. they are geographic places where the competition for land between agriculture and nonagriculture (urban built-up property) is intense leading to the vanishing of rural agricultural land rights. formal and informal actors play a significant role in the process of converting peri-urban agricultural lands into urban builtsara et al. east african journal of sciences volume 15 (2): 129-140 130 up non-agricultural properties. therefore, urban built-up properties in the peri-urban areas are the results of land use conversion through the informal and formal channels (achamyeleh gashu, 2020). as demand for land for residential, commercial and manufacturing expansions increased over time, urban centers have been physically expanding their boundaries to surrounding rural and peri-urban areas by including additional land where people did base their lives in agriculture (sdc, 2017). therefore, peri-urban areas located adjacent to the municipal boundaries have become the most dynamic areas in ethiopia. they are places where all forms of lively competitions for land are fierce. due to the rural-urban dichotomy of land holding systems in ethiopia, urbanization and urban development in peri-urban areas involves land holding right acquisition and transfer issues. in the process of urban expansion and development in ethiopia, peri-urban landholders or farmers’ land rights are forcibly taken by the state and thereafter reallocated to urban residents and private developers through lease agreement. at the same time, the informal acquisition and development of land is a commonly observed phenomenon in the transitional periurban areas of ethiopia (achamyeleh gashu, 2020). on the other hand, ethiopia’s urban expansion and development strategy has been based on the acquisition of land by government from adjacent peri-urban areas. the land in the peri-urban areas is predominantly agricultural in nature. thus, in the process of urbanization, local peri-urban landholders or indigenous small farmers are largely vulnerable to loss of their land wherein their livelihood is based (achamyeleh gashu, 2014b). the peri-urban farming community used to extract resource from their environment and meet their livelihood requirement. this livelihood is totally dependent on the land, which is the main source of livelihood of the peri-urban farming community. however, if the land is alienated to urban built-up activities, the livelihood of the peri-urban farming community may be disturbed (efa tadesse and gutema imana, 2017). unfortunately, peri-urban livelihood issues are hardly addressed in urban development policy making and planning, which rather commonly focus on physical issues such as land use for residential and commercial, housing supply to the urbanities, and infrastructure development to the area and so on (achamyeleh gashu, 2014). moreover, most empirical research concerned with livelihood issues focus on rural farming community and urban areas, i.e., most of the researchers have not addressed peri-urban communities. thus, it is necessary to answer questions like ‘what livelihood strategy choices of periurban communities are and what factors do affect them’ and ‘whether there are correlations between the strategy choices or not’ in order to generate insights which may help the concerned agencies to design and implement effective urban development programs and strategies that include periurban communities. therefore, the objective of this study was to identify the livelihood strategy choices of periurban communities of hossana town and factors affecting them. 2. research methodology 2.1. study area the study was carried out at hossana town administration, the administrative center of hadiya zone, southern ethiopia. the town is located in lemo woreda (district) of the zone located at the distance of 232 km to the south of addis ababa and 168 km from hawassa, the capital of the region (hossana city administration, 2017). total area of hossana is 40.5 km2. the mean annual temperature is 15.1 to 20 °c, mean annual rainfall is 1001 to 1200 mm and the elevation ranges from 2000 to 2500 meters above sea level. it has a latitude and a longitude of 7°30′ to 7°35′n and 37°48′ to 37°52′e (bofed, 2018). the administrative division of the town was reformed in 2018/2019 and it is divided into 3 sub towns, 6 urban kebeles, 16 ketenas, 51 sefers and 253 tabiyas (htfedo, 2019). kebele is the smallest administrative unit, followed by ketena, sefer, and tabiya in an increasing order of size, respectively. since the time of its establishment, the population of hossana town has been increasing rapidly. it is now one of the most populated towns in ethiopia. for instance, its total population was 13,467 in 1984; 31,701 in 1994 and 69,957 in 2007 (htfedo, 2019). in 2017/2018 the total population of the town reached 117,231 with a population density 2,859 person per km2. the average family size of the town is 4.0 whereas total number of households is 29,308 (bofed, 2019). according to a census conducted by the town’s administration in 2017/18, the total population of hossana town is 177,954 (htfedo, 2019). hossana is one of the oldest towns in southern ethiopia, which was established in 1906, and undergoes through different administrative and economic systems: feudal, social and capitalist system. each system had its own impact on growth of the town. growth of hossana town was stagnant during the regimes of emperor haile selassie and derg. the change in economic and administrative system in the 1990s resulted in a remarkable growth (addisyihun abayneh, 2019). a horizontal growth of the town is mainly in the eastern and north western part with a small expansion towards the southwestern parts relative to other directions because of the landscape of the town. the trend and extent of changes in built-up areas is likely to continue with the rapid increments in the development of infrastructure and population (tagesse eromo, 2019). sara et al. factors affecting choice of livelihood strategies 131 figure 1. geographic map of the study area. 2.2. sampling techniques members of the sample population were drawn from expropriated and non-expropriated households in the peripheries of hossana town. it was hypothesized that the two groups had income and expenditure differences and thus, stratified sampling technique was applied. the study used multi-stage sampling method to select the sample respondents. in the first stage, hossana town was selected purposively, because of its drastic horizontal urban expansion. next, seven sample kebeles with higher urban expansion towards the peri-urban areas were selected purposively from the town. additionally, seven sample rural kebeles around of the town were also purposively selected. then households were stratified into expropriated and non-expropriated groups. lists of expropriated households in the last five years (2013/14–2017/18) were obtained from the three subtown municipality offices, and lists of non-expropriated farmers were obtained from kebele offices. finally, the study selected sample households using a systematic random sampling technique from the respective list of households using probability proportional to sample size (pps) to both expropriated and non-expropriated households. the sample size was obtained using cochran (1963) formula to produce a yield of a proportionate sample size. 2 2 )(e pqz n = ; (1) where, n = desired sample size; z2 = the abscissa of the normal curve that cuts off an area α at the tails; e = the desired level of precision; p = the estimated proportion of an attribute that is present in the population; and q = 1-p. in this case, p was the proportion of expropriated households and q was the proportion of nonexpropriated households which took 40% and 60% share of the total population respectively. therefore, the sample size was: 𝑛 = (1.96)2(0.4)(0.6) (0.05)2 = 369 per the proportion, sample of expropriated and nonexpropriated households were 148 and 221 respectively. prior to conducting the interview, the researcher carried out a pre-test of the interview schedule out of sample kebeles in 18 expropriated and 18 non-expropriated households and accordingly made revision and finalized the questionnaire. the researcher also collected primary qualitative and quantitative data through the combination of a household survey, personal observations, key informant interviews, focus group discussions; case story and transect-walk and secondary data using note taking, reviewing and library methods from government reports and publication, books, articles, and reports of related institutions. sara et al. east african journal of sciences volume 15 (2): 129-140 132 2.3. method of data analysis primary data were collected from sample households and analyzed qualitatively and quantitatively. the quantitative data were analyzed using both descriptive statistics and econometric methods. 2.3.1. multivariate probit (mvp) model social studies often yield binary or dichotomous data due to the lack of adequate and direct continuous measurements. indeed, correlated dichotomous data arise in many settings, ranging from measurements of random cross-section subjects to repeated measurements in longitudinal studies. the mvp model is a popular method in econometrics for analyzing this kind of data. this model is described in terms of a correlated multivariate normal distribution of the underlying latent variables that are manifested as discrete variables through a threshold specification, and hence allows the flexible modeling of the correlation structure and easy interpretation of the parameters (song and lee, 2005). multinomial choices of individuals are likely to be correlated. nonetheless, econometric models for this phenomenon are scarce (bel and paap, 2014). and multinomial models do not show multicollinearity between multinomial choices of individuals. moreover, individuals cannot choose more than one option. thus, it was necessary to use a model appropriate for analyzing dichotomous data. therefore, mvp model was used identify determinants of livelihood strategy choice of periurban communities. the other alternatives for mvp are conditional logit, mixed and multivariate tobit models. conditional logit employs choice specific data whereas mixed logit is used when the data are mixed (both choice specific and chooser specific). since the data used in this study were chooser specific (vary across individuals), these models were not appropriate. on the other hand, multivariate tobit model is appropriate to show not only the probability but also the intensity of choices. but the concern of this study was to show the probability of different livelihood strategy choices. 2.3.2. model specificationaccording to greene (2012) consider the m-equation multivariate probit model: the model is characterized, for each observation, by m pairs of equations, one describing each latent dependent variable and the other describing the corresponding binary observed outcome.       ( )  .,0~,..., ,,...,, ,1,..., ,0,..., ,,.....,1,0,01, 1 1 1 1 *'* rnm jmxxcov xxvar xxe mmotherwiseifyyxy m mmj mm mm mmmmmm      = = = ==+= (2) m  , m = 1, …, m, are error terms distributed as multivariate normal, each with a mean of zero, and variance-covariance matrix v, where v has values of 1 on the leading diagonal and correlations ρjm = ρmj as offdiagonal elements for j, m = 1, …, m and j ≠ m. the joint probabilities of the observed events,   nixxxyyy imiiimii ,...,1,...,,,...,, 2121 = that form the basis for the log-likelihood function, are the m-variate normal probabilities, ( ),,,..., * 1 ' 11 rxqxql mimimiimi = (3) where, ,12 −= imim yq . * jmimijjm qqr = testing for multicollinearity: prior to conducting econometric analysis, it was imperative to check whether there was multicollinearity among the continuous explanatory variables and verify the degree of associations among dummy explanatory variables. therefore, in order to see the degree of association between dummy or discrete variables contingency coefficient was computed and vif was done whether there was multicollinearity between continuous explanatory variables or not. dependent variable of the model: the household livelihood strategy choices, which was the dependent variable for multivariate probit analysis, was a polychotomous variable. it was represented in the model as: agriculture: income from agriculture = 1, 0 otherwise. cottage or small scale industry: income from cottage or small scale industry = 1, 0 otherwise. service: income from service = 1, 0 otherwise. other livelihood strategies: income from remittance from other relatives, selling household asset and compensation = 1, 0 otherwise. sara et al. factors affecting choice of livelihood strategies 133 table 1. the independent variables of the model. variable expected sign agri. indus. serv. migr. other age (years) is a continuous variable peculiar to the household head. + – – – + dependency ratio (%) is a continuous variable and refers to the ratio of children under age 15 and old age of above 64 to the family member between age of 15 and 64. + – – – + active labor force in the family (no.) is a continuous variable and refers to the number of family members between age of 15 and 64. + + + + – sex is a dummy variable that takes the value 0 for female and 1 otherwise. + + + + – educational level of the household head (years) is a continuous variable taking value of years of schooling. + + + – – credit use: is a dummy variable taking a value of 1 if the household uses credit, 0 otherwise. + + + – – total income (birr) is a continuous variable and refers income earned from on farm, off farm and nonfarm activities. + + + – – health of the household head is a dummy variable taking a value of 1 if the household head is healthy, 0 otherwise. + + + – – cosmopoliteness is a dummy variable taking a value of 1 if the household head is cosmopolite, 0 otherwise. + + + – – market distance (kms) is a continuous variable, which refers to the distance that the household’s home is away from the surrounding area local market. + – – + + job opportunity is a dummy variable taking a value of 1 if the household has formal and informal job opportunity, 0 otherwise. – + + – – household asset ownership is a continuous variable and refers the assets of the household, other than livestock and cultivated land, such as house, vehicles, bicycle, cart, tree plants, enset, chat and other durable goods valued in birr. + + + – – mass media exposure is a dummy variable taking a value of 1 if the household head has exposure to different media like radio, television, newspaper, magazine, brochure, and social electronic media, 0 otherwise. + + + – – achievement motivation is a dummy variable taking a value of 1 if the household head has achievement motivation, 0 otherwise. + + + – – information seeking behavior is a dummy variable taking a value of 1 if the household head has information seeking behavior, 0 otherwise. + + + – – distance to public transport (km) is a continuous variable, which refers to the amount of kilometer that the household’s home is away from the surrounding area public transport. + – – + + cash saving practice is a dummy variable taking a value of 1 if the household practices saving, 0 otherwise. + + + – – membership to cooperatives is a dummy variable of which the value is 1 if the household head is member of cooperative and 0, otherwise. + + + – – road access is a dummy variable taking a value of 1 if the household has access to road in its locality, 0 otherwise. + + + – – total cultivated land (ha) is a continuous variable. + + + – – livestock owned other than ox (tlu) is a continuous variable and indicates the livestock size excluding ox. + + + – – oxen ownership (no.) is a continuous variable. + + + – – input use is a dummy variable and takes a value of 1 if they are users and 0, otherwise. this refers to use of different agricultural inputs by the farming households. + + + – – extension contact (no.) is a continuous variable and is the number of times the household head contact with the extension personnel during the immediate last crop year. + + + – – notes: agri. = agriculture; indus. = cottage/small scale industry; serv. = service; and migr. = migration. sara et al. east african journal of sciences volume 15 (2): 129-140 134 3. results and discussion testing for multicollinearity: before fitting the model, the problem of multicollinearity among explanatory variables was checked by using variance inflation factor (vif) and pearson correlation matrix. the problem of multicollinearity was not serious among variables because of vif value less than 10 and tolerance less than 1. similarly, multicollinearity was not a serious problem between dummy variables as the value of contingency coefficient less than 0.5 assumes weak association between variables. therefore, all of the variables were included in the model. 3.1. livelihood strategy choices of peri-urban communities the livelihood strategies pursued by peri-urban communities of the study area were identified as agriculture, cottage/small scale industries, service, migration and others. these livelihood strategies were used in the mvp model and are presented in table 2. according to the table, the χ2 –value for the distribution of cottage/small scale industry shows that there was no significant difference between expropriated and nonexpropriated households. but the χ2 –values between the two groups for the rest four livelihood strategies show significant differences. table 2. descriptive statistics of livelihood strategies used in the mvp model (n = 369). livelihood strategy description total sample (n = 369) expropriated (n = 148) non-expropriated (n = 221) χ2 value frequency (%) frequency (%) frequency (%) agriculture yes 354(95.90) 133(89.90) 221(100.0) 23.348*** no 15(4.10) 15(10.10) 0(0.0) cottage/small scale industry yes 20(5.40) 10(6.80) 10(4.52) 0.8613 no 349(94.60) 138(93.20) 211(95.48) service yes 212(57.50) 98(66.20) 114(51.60) 7.764*** no 157(42.50) 50(33.80) 107(48.40) migration yes 59(16.0) 31(20.90) 28(12.70) 4.52** no 310(84.0) 117(79.10) 193(87.30) other livelihood strategies yes 77(20.90) 51(34.50) 26(11.80) 27.648*** no 292(79.10) 97(65.50) 195(88.20) 3.2. econometric results of mvp model the mvp model results showing the marginal effects of explanatory variables are presented in table 3 below. the wald test (χ2 (115) = 210.41, p> χ2 = 0.000) was significant at 1% significant level. this indicates that the subset of coefficients of the model was jointly significant and that the explanatory power of the factors included in the model were satisfactory; thus, the mvp model fitted the data reasonably well. the null hypothesis for test of independence was rejected for all livelihood choices, as the likelihood ratio test (χ2 (10) = 32.656, p> χ2 = 0.000) of independence of error terms was significant at 1% significant level. thus, use of mvp was justified indicating that the model was capturing wider effects than the single equation-probit model. thus, the equations were inter-dependent. this verifies that separate estimation of choice decision of the livelihood strategies was biased, and the decisions to choose the five livelihood strategies were interdependent decisions. similarly, most of pair wise correlation coefficients (rho) were significant. rho21 (the correlation between cottage/small scale industry and agriculture) and rho54 (the correlation between other livelihood strategy and migration) were positively correlated and significant at less than 10% and 1% probability levels, respectively. rho41 (the correlation between migration and agriculture), rho51 (the correlation between other livelihood strategy and agriculture), rho52 (the correlation between other livelihood strategy and cottage/small scale industry), and rho53 (the correlation between other livelihood strategy and service) were negatively interdependent and significant at less than 1%, 5%, 1% and 1% probability levels, respectively. it indicates that households using cottage/small scale industry as a livelihood strategy were more likely to use agriculture as a livelihood strategy (rho21). likewise, households choosing other livelihood strategies were more likely to diversify it with migration (rho54). however, households using migration as their income source were less likely to pursue agriculture (rho41); and households using other livelihood strategy were less likely to diversify it with agriculture (rho51), cottage/small scale industry (rho52) and service (rho53). it also indicates that two sets of livelihood options (cottage/small scale industry with agriculture and other livelihood strategy with migration) were complimentary to each other; while migration with agriculture and other livelihood strategy with agriculture, cottage/small scale industry and service were competitive to each other. this implies that households use migration as a substitute to agriculture and use other livelihood strategies as a substitute to agriculture, cottage/small scale sara et al. factors affecting choice of livelihood strategies 135 industry and service. the possible justification for competitive relation of other livelihood strategies with agriculture, cottage/small scale industry and service is that most of the time households use other livelihood strategies like selling household asset and remittance from other relatives when they do not have income from other sources. the probability that households choose agriculture, cottage/small scale industry, service, migration and other as a livelihood strategy is 95.87%, 5.36%, 56.87%, 15.46% and 20.96%, respectively. this indicates that the probability of choosing agriculture was the highest (95.87%) and contrary to that the likelihood to choose cottage/small scale industry was the least of all (5.36%). this is obvious that agriculture is common in peri-urban and rural areas, and thus it takes the highest share. cottage/small scale industries including construction, mining and handicraft were insignificant in the study area. service (56.87% probability to be chosen) is common for peri-urban and rural residents. as in the study area migration to republic of south africa is common, migration took 15.46% probability to be chosen while other livelihood strategies including remittance (mostly from migrated) relatives and selling household asset took the probability of 20.96% to be chosen. the joint probabilities of success or failure of choosing five livelihood strategies suggests that the likelihood of households to jointly choose the five strategies was low which was 0.056% and the failure to jointly choose them was 0.268%, i.e., they were less likely to succeed and fail to jointly choose the five strategies. the result in table 3 reveals that out of 24 explanatory variables which can affect livelihood strategy choice, 14 of them namely dependency ratio, active labor force in the family, sex of household head, educational level of household head, annual total income, market distance, household asset ownership, mass media exposure, achievement motivation, information seeking behavior, distance to public transport, total cultivated land, livestock (other than ox) and extension contact had significant effect. five explanatory variables were significant at one livelihood strategy choice; six explanatory variables were significant at two livelihood strategy choices; and three explanatory variables were significant at three livelihood strategy choices. agriculture, cottage/small scale industry, service, migration and other livelihood strategies were significantly affected by four, seven, six, four and five explanatory variables at different probability levels, respectively. three variables (credit use, job opportunity and road access) were dropped since they predict success on agriculture perfectly. dependency ratio (depratio): the mvp regression output shows that dependency ratio was found as one of the influential factors of livelihood strategy choice which affected the probability of choosing agriculture and cottage/small scale industry positively at less than 5% and 1% probability levels, respectively. other factors kept constant, for a one unit increase in dependency ratio, there were a 0.1% and a 0.02% increases in the predicted value of households’ livelihood strategy choice of agriculture and cottage/small scale industry, respectively. the positive association of dependency ratio with agriculture could be due to the fact that households with more dependent members do not have extra labor to share for other livelihood strategies. a similar finding by adugna eneyew and wegayehu bekele (2012) revealed that dependency ratio found to have a significant positive correlation with choice of agriculture and nonfarm strategy. misganaw teshager et al. (2019) revealed opposite finding that households with more dependents were less likely to choose on-farm activities and also gebrehiwot woldegebrial et al. (2018) found that households with high dependency ratio had low probability level to participate in off-farm and non-farm income-generating livelihood diversification strategies. on the other side, positive association between dependency ratio and cottage/small scale industry could be due to households with dependent members above 64 tend to practice cottage industry like traditional handicraft, household utensils etc. at their pension age. this finding is in line with misganaw teshager et al. (2019) that households with more dependents tended to choose non-farm livelihood activities. active labor force in the family (actlab): the model result indicates that active labor force in the family had been found as one among the most influential factors of livelihood strategy choice. it had a positive relationship with a probability of choosing agriculture and cottage/small scale industry and significant at less than 5% and 10% probability levels, respectively. ceteris paribus, for a one unit increase in active labor force, there were a 4.7% and a 0.6% increases in choosing agriculture and cottage/small scale industry, respectively. this result implies that households with more active labor forces had extra labor force to share for agriculture and cottage/small scale industry like mining and construction. on contrary, the result by xu et al. (2015) suggests that dependence on agriculture is negatively associated with the number of laborers. sex of household head (sexhhh): this variable had a negative relationship with the probability of choosing cottage/small scale industry and significant at less than 10% probability level. males were taken as the reference category and the negative coefficient of the analysis indicates the relationship with males. therefore, other factors being constant, for the male headed household, the choice for cottage/small scale industry was decreased by 3.8% as compared to female headed households. this implies that female headed households were more likely to practice cottage/small scale industry than their male counterparts. an empirical study conducted in sululta sara et al. east african journal of sciences volume 15 (2): 129-140 136 district by dereje tesema (2018) revealed that females participate in non-farm livelihood activities 28 times more than males. where there is male labor constraint, females share cropped their land and more engage in non-farm living. in addition to this, traditional brewing and handcraft absorbs large labor of females in the study area. educational level of household head (edulev): it was found that educational level of the household head had a negative and significant effect on the probability of choosing migration at less than 1% probability level. a one year increase in level of education was associated with a 1.2% decrease in the predicted value of choosing migration, holding other variables constant. this finding confirms the assumption that more educated household heads do not let their family members to migrate to other places in the country as well as to abroad. paulos lukas and thomas dana (2017) also found that more educated farmers can better access better means of livelihood than illiterate in urban expansion. annual total income (totincome): from table 3, the result of the econometric analysis shows that annual total income positively influenced both the probabilities of choosing service and migration at less than 1% probability level each. for a 1 birr increase in annual total income, there were a 51.2% and a 10.2% increases in the choice of service and migration, respectively, ceteris paribus. from the result, it is indicative that households with better income could have initial capital to be engaged in different service providing activities like trade, transport, hotel, etc. likewise, households with better income could invest to send their family member abroad to better economic prospects. this result is not in line with misganaw teshager et al. (2019) that household income had a significant negative influence on non-farm livelihood activities. market distance (markdist): it was found that market distance was among the most influential factors that affected the livelihood strategy choice. it affected the likelihood of choosing cottage/small scale industry negatively at less than 5% probability level while it affected the probability of choosing migration and other livelihood strategies positively at less than 10% probability level each. keeping other things in the model constant, for a 1km increase in market distance, there were a 1.5% decrease in choosing cottage/small scale industry, a 3.1% and a 3.4% increase in choice of migration and other livelihood strategies, respectively. as cottage industry is based on market access, it shows a negative association whereas households with not liaison to market access prefer migration and other livelihood strategies like remittance and selling household assets. from the result, we could suggest that the livelihood strategy choices of the households farther from market are limited to the choices like migration, remittance and selling household assets as they do not have incentive to choose different service giving activities and cottage industry due to distance from market. previous studies, for example geremew worku et al. (2017), bereket tufo et al. (2018), dereje tesema (2018), gebrehiwot woldegebrial et al. (2018) and tariku lorato (2019) show similar results that a household residing in far distance to market are less likely to diversify the livelihood strategies into different combination of income sources. household asset ownership (hhasset): the result shows that household asset ownership positively affected the likelihood of choosing service and other livelihood strategies at less than 10% and 1% levels, respectively. accordingly, a one unit increase in household asset ownership was associated with a 5.8% and a 5.0% increases in the choices for service and other livelihood strategies, ceteris paribus. this finding confirms the assumption that asset was necessary and complementary to service and other livelihood strategies like selling household assets. mass media exposure (massmed): it was found that mass media exposure had a negative and significant effect on the probability of choosing other livelihood strategies at less than 5% probability level. the negative coefficient implies that a predicted value of choice for other livelihood strategies was decreased by 19.1% in households having mass media exposure than those not having, keeping other factors constant. in other words, households which hadn’t exposure to mass media preferred other livelihood strategies, i.e, remittance and selling household assets. achievement motivation (achievmot): in table 3, the model result shows that achievement motivation was one of the most influential factors of livelihood strategy choice that affected the probability of choosing agriculture negatively at less than 10% probability level whereas it affected the likelihood of choosing cottage/small scale industry and service positively at less than 10% and 1% probability levels, respectively. keeping other things in the model constant, for household heads having achievement motivation, there were a 9.0% decrease, a 2.1% increase and also a 32.6% increase in choice of agriculture, cottage/small scale industry and service, respectively as compared to those household heads not having achievement motivation. the possible justification for this finding could be that achievement motivation might be the reason to prefer cottage/small scale industry and service to agriculture. sara et al. factors affecting choice of livelihood strategies 137 table 3. multivariate probit model result. variable livelihood strategy choice agriculture (df/dx) cottage industry (df/dx) service (df/dx) migration (df/dx) other (df/dx) agehhh –0.0003 (0.002) –0.001(0.001) 0.001(0.003) –0.002(0.002) –0.001(0.002) depratio 0.001(0.0005)** 0.0002(0.0001)*** –0.001(0.001) –0.0004(0.0004) –0.0001(0.0004) actlab 0.047(0.018)** 0.006(0.004)* –0.022(0.021) –0.020(0.013) –0.010(0.014) sexhhh –0.017(0.041) –0.038(0.033)* –0.102(0.079) 0.030(0.043) –0.038(0.063) edulev –0.002(0.004) 0.0002(0.001) 0.010(0.008) –0.012(0.004)*** 0.002(0.005) creduse variable dropped 0.025(0.028) –0.099(0.095) –0.026(0.059) 0.036(0.072) totincome –0.004(0.037) 0.017(0.013) 0.512(0.078)*** 0.102(0.038)*** –0.057(0.044) healthhhh –0.024(0.050) 0.005(0.014) –0.181(0.097) –0.026(0.070) –0.039(0.075) cosmoplite –0.038(0.039) 0.009(0.011) 0.074(0.089) 0.055(0.043) –0.101(0.069) markdist –0.022(0.024) –0.015(0.007)** 0.034(0.028) 0.031(0.018)* 0.034(0.020)* joboppo variable dropped –0.021(0.013) 0.084(0.075) –0.039(0.046) –0.071(0.050) hhasset –0.020(0.020) –0.009(0.006) 0.058(0.030)* 0.023(0.017) 0.050(0.019)*** massmed –0.045(0.040) 0.013(0.010) 0.119(0.127) 0.053(0.058) –0.191(0.108)** achievmot –0.090(0.040)* 0.021(0.011)* 0.326(0.113)*** –0.007(0.070) –0.062(0.087) infoseek 0.122(0.083)* –0.017(0.019) –0.185(0.085)** 0.038(0.048) 0.102(0.051)* distpubtran 0.033(0.033) 0.014(.007)** 0.008(0.035) 0.001(0.023) 0.005(0.025) cashsaving 0.024(0.036) –0.018(0.013) 0.124(0.076) –0.014(0.044) 0.019(0.053) membcoop –0.028(0.051) 0.004(0.015) –0.108(0.079) 0.032(0.049) 0.039(0.057) roadacc variable dropped 0.003(0.013) 0.043(0.079) 0.036(0.047) 0.005(0.055) totcult – 0.003(0.008) –0.287(0.058)*** –0.058(0.033)* –0.029(0.040) livotherox – 0.001(0.004) 0.072(0.026)*** 0.009(0.014) –0.002(0.018) oxenown – –0.007(0.007) –0.041(0.041) –0.003(0.027) –0.035(0.036) inputuse – –0.013(0.022) 0.058(0.125) –0.042(0.068) –0.120(0.083) extenscont – –0.007(0.003)** –0.009(0.010) 0.002(0.006) 0.017(0.007)** predicted probability 95.87% 5.36% 56.87% 15.46% 20.96% joint probability of success 0.056% joint probability of failure 0.268% log likelihood –552.144 number of draws (#) 5 number of observation 366 wald chi2(115) 210.41 prob> χ2 0.000 rho1 rho2 rrho3 rho4 rho5 rho1 1 rho2 0.386(0.202)* 1 rho3 – – 1 rho4 –0.449(0.134)*** – – 1 rho5 –0.386(0.149)** –0.353(0.165)*** –0.317(0.100) *** 0.345(0.106)*** 1 likelihood ratio test of rho21 = rho31 = rho41 = rho51 = rho32 = rho42 = rho52 = rho43 = rho53 = rho54 = 0: χ2 (10) = 32.656 prob> χ2 = 0.000 note: ***, **, and * represent 1%, 5% and 10% level of significance. the figures in the parentheses refer to the standard error. the variables which predict success perfectly are dropped. sara et al. east african journal of sciences volume 15 (2): 129-140 138 information seeking behavior (infoseek): this was the other most influential factor in the choice of livelihood strategy in the study area. the model output shows that a negative and significant association between information seeking behavior and the probability of choosing service, and a negative and significant associations between information seeking behavior and the likelihood of choosing agriculture and other livelihood strategies. the results were significant at less than 5% probability level for service and significant at less than 10% probability level for agriculture and other livelihood strategies each. a predicted value of choosing service was 18.5% lower and choosing agriculture and other livelihood strategies were 12.2% and 10.2% higher, respectively, for household heads having information seeking behavior than those not having, holding other factors constant. this finding implies that household heads with information seeking behavior preferred agriculture and other livelihood strategy (remittance and selling household asset) to service. distance to public transport (distpubtran): this variable had a positive relationship with the likelihood of choosing cottage/small scale industry and it was significant at less than 5% probability level. for a 1km increase in distance to public transport, there was a 1.4% increase in the choice of cottage industry, keeping other factors constant. this could be due to the farther households from public transport might choose small scale industry like quarrying. total cultivated land (totcult): the multivariate probit regression result indicates that total cultivated land was among the influential factors of livelihood strategy choice that affected the probability of choosing service and migration negatively at less than 1% and 10% probability levels, respectively. holding other factors in the model constant, for a 1ha increase in total cultivated land, there were a 28.7% and a 5.8% decreases in choosing service and migration, respectively. this result is in line with the assumption that households with larger cultivated do not tend to diversify their livelihood with non-farm activities. this finding is consistent with mathewos mentamo and negatu regassa (2016), agidew abebe (2018) and bereket tufo et al. (2018) that found an inverse relationship between land ownership and livelihood diversification. dereje tufo (2018) and kassahun tassie (2018) also found that an increase in size of landholdings decreases the likelihood of engaging in multiple livelihood activities. contrary to these, gebrehiwot woldegebrial et al. (2018) and tagesse abo (2018) found that households with larger area of land for cultivation tend to diversify their livelihood more. livestock owned (other than ox) (livotherox): livestock owned (other than ox) was found to affect the likelihood of choosing service positively at less than 1% probability level. a 1-tlu increase in livestock ownership (other than ox) was associated with a 7.2% increase in the predicted value of choosing service, holding other variables constant. the positive relationship implies that livestock holding excluding oxen for draft purpose help households to diversify their income portfolios with service. households with no oxen could not be engaged in farming, thus they might tend to diversify their income sources with non-farm activities. misganaw teshager et al. (2019) reported a similar result that livestock holding had a significant positive effect on the choice of non-farm livelihood activities. this result is not in line with tagesse abo (2018) that number of livestock (excluding oxen) owned by a household influenced the probability of diversifying livelihood strategies negatively. agidew abebe (2018), bereket tufo et al. (2018), gebrehiwot woldegebrial et al. (2018) and tariku lorato (2019) also found that a household having larger size of livestock are less likely to diversify the livelihood strategies. extension contact (extenscont): this variable was found among the influential determinants of livelihood strategy choices that affected the probability of choosing cottage/small scale industry negatively at less than 5% probability level and affected the likelihood of choosing other livelihood strategies positively at 5% probability level. holding other variables in the model constant, for a one unit increase in the frequency of extension contact, there were a 0.7% decrease and 1.7% increase in choosing cottage/small scale industry and other livelihood strategies, respectively. in other words, households with more frequency of extension contact did not diversify their livelihood strategy with industry, but pursue other livelihood strategies to increase their income. 4. conclusion and recommendation the results of the study have demonstrated that periurban households with more dependent members, active labor forces and information seeking behavior tended to choose agriculture as a source of income. cottage/small scale industry was likely to be chosen by households having more dependent members, active labor forces, achievement motivation and which were far from public transport. service as source of income was chosen by those households with higher income, household asset, achievement motivation and livestock ownership. households which had higher income and those were far from market were likely to choose migration as livelihood strategy. other livelihood strategies like remittance and selling household asset were income sources for those households far from market, had more household asset, had information seeking behavior and had higher frequency of extension contact. on the other hand, households with more achievement motivation did not sara et al. factors affecting choice of livelihood strategies 139 choose agriculture as income source; and households headed by male, far from market and higher frequency of extension contact were not likely to choose cottage/small scale industry as livelihood strategy. households which had information seeking behavior and large cultivated land were unlikely to choose service as their income source. migration as source of income was not preferred by households with educated head and having large cultivated land. households having mass media exposure did not choose other livelihood strategies like remittance and selling household assets. the results of this study imply that peri-urban communities need strong attention of urban policy makers. therefore, it is recommended for peri-urban community that awareness for appropriate and effective use of human and financial resources should be created; participation of women in all sectors, development of industry and service sectors integrated with market access and other social facilities should be achieved; and 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2005. a multivariate probit latent variable model for dichotomous responses. statistica sinica, 15(2005): 645–664. tagesse abo. 2018. livelihood diversification strategies of farm households in kembata tembaro zone, ethiopia. phd dissertation, wolaita sodo university, ethiopia. pp. 201. tagesse eromo. 2019. land use and land cover change detection analysis using remote sensing and geographic information system: a case study of hosaena town, southern ethiopia. msc thesis, addis ababa university, ethiopia. pp. 54. tariku lorato. 2019. the determinants of livelihood diversification strategies in qecha bira woreda, kambata tambaro zone, southern ethiopia. journal of economics and sustainable development, 10(9): 6–14. woltjer, j. 2014. a global review on peri-urban development and planning. jurnal perencanaan wilayah dan kota, 25(1): 1–16. xu, d., zhang, j., rasul, g., liu, s., xie, f., et al. 2015. household livelihood strategies and dependence on agriculture in the mountainous settlements in the three gorges reservoir areas, china. sustainability, 7: 4850–4869. https://doi.org/10.1080/23311886.2018.1562508 https://doi.org/10.1080/23311886.2018.1562508 ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(1): 15–30 licensed under a creative commons *corresponding author: kmulugetak@yahoo.com attribution-noncommercial 4.0 international license. genetic diversity of ethiopian groundnut (arachis hypogaea l.) accessions mohammed abdella1, mulugeta kebede2*, and tileye feyissa3 1department of biotechnology, college of natural and computational science, wollo university, p.o. box 1145, dessie, ethiopia 2department of plant biology and biodiversity management, college of natural science, addis ababa university, p.o. box 1176, addis ababa, ethiopia 3institute of biotechnology, college of natural science, p.o. box 1176, addis ababa university, addis ababa, ethiopia abstract background: groundnut (arachis hypogaea l.) is the world’s most important source of edible oil and vegetable protein. understanding its genetic diversity is important for the sustainable use and conservation of the crop. to our knowledge, little is known about the genetic variability of cultivated ethiopian a. hypogaea. objective: to determine the genetic variability and diversity of 43 accessions of a. hypogaea collected from different regions of ethiopia using issr markers. materials and methods: seeds of 43 a. hypogea accessions collected from different regions of ethiopia by ethiopian biodiversity institute were planted in plastic pots in a greenhouse of melkasa agricultural research center. young fresh leaves from four weeks old plants were used to extract genomic dna using ctab (cetyl trimethyl ammonium bromide) method. four reproducible issr primers were used for amplification and the amplified products were separated on 1.67% agarose gel. percentage of polymorphic bands, polymorphic information content (pic), the mean nei’s gene diversity and shannon’s information index were determined. ntsys-pc version 2.02 software was used to calculate the jaccard’s similarity coefficient for all possible pairs of samples. results: out of 56 reproducible bands generated, 29 (51.8%) were polymorphic. the band size ranged from 120 bp to 1100 bp. the polymorphic information content (pic) value ranged from 0.29 to 0.76 with the average value 0.49. the mean nei’s gene diversity and shannon’s information index were 0.25 and 0.33, respectively. genetic relationship between a. hypogaea accessions based on jaccard’s pair wise similarity coefficients varied from 44% to 83% with an average value of 63.5%. the upgma analysis grouped a. hypogaea accessions into five distinct clusters at 63.5% similarity coefficient, and the principal coordinate analysis revealed similar grouping. conclusions: issr marker-based analysis showed the presence of genetic variability among the accessions. upgma and pcoa clustered most of the accessions irrespective of their geographic origins. in addition, the current study demonstrated the informativeness of issr markers in estimating the extent of genetic variation among a. hypogaea accessions. this study is a milestone for future conservation and breeding program of the crop. we recommend further investigation with more geographic range and additional molecular markers to elucidate a clear genetic diversity of groundnut in ethiopia. keywords: jaccard’s similarity coefficient; nei’s gene diversity; polymorphism; polymorphism information content; shannon’s weaver index mohammed et al. east african journal of sciences volume 16(1): 15–30 16 1. introduction groundnut or peanut (arachis hypogaea l.) belongs to the family leguminoseae and genus arachis. cultivated groundnut is a highly self-pollinated, allotetraploid annual legume with 2n = 4x = 40 with a basic chromosome number of x =10 (stalker, 1997). groundnut is cultivated and grown throughout the tropics and sub-tropics between 40° south and 40° north of the equator where the annual rainfall ranges between 500 to 1200 mm and the average daily temperature is higher than 20 °c (mastewal alehegn et al., 2017). major groundnut growing countries include china, india, the united states and nigeria (taru et al., 2010). globally, groundnut is grown in 26.4 million ha worldwide with a total production of 37.1 million metric tons and an average productivity of 1.4 metric tons ha–1 (hamakareem et al., 2016). groundnut is the world’s 4th most important source of edible oil and 3rd most important source of vegetable protein (hamakareem et al., 2016). groundnut seeds contain 42–50% oil, 26% protein, 18% carbohydrates, and are rich source of riboflavin, thiamine, nicotinic acid and vitamin e (kathirvelan and kalaiselvan, 2007). arachis hypogaea is one of the four economically important oilseed crops along with noug, flax and sesame in ethiopia (mastewal alehegn et al., 2017). besides, this crop helps small-scale producers in getting significant revenue and helps ethiopia in getting foreign currency earnings through export. being a legume, this plant improves soil by fixing nitrogen biologically without consuming non-renewable energies and without disturbing agro-ecological balance (jiaramraja and fantahun woldesenbet, 2014). in ethiopia, groundnut is grown and covers nearly 87,925.23 hectares (csa, 2020) of arable land per annum and the major producing zones are eastern hararghe zone in oromia as well as metekel in benishangulgumuz regional state (fredu nega et al., 2015; addisu getahun and ermias tefera, 2017). despite its importance, the national average yield produced by the farmers in ethiopia is considerably low, 1.3 tons ha–1, indicating the need of maximum effort to improve productivity (gebreselassie redae et al., 2014). the gap observed between actual and potential yields is due to several factors, including non-availability of seeds of improved varieties, poor soil fertility, inappropriate crop management practices, insect pests and fungal diseases (geleta tarekegn et al., 2007; geremew terefe and asfaw tulu, 1992). genomic research can provide new tools and resources to revolutionize crop genetic improvement and production. it also provides accurate knowledge at molecular level, which is not possible with phenotypic markers (johan et al., 2011). assessment of genetic diversity is an important step in any crop improvement program (bhandari et al., 2017). understanding the molecular basis of the essential biological phenomena in plants is crucial for the effective conservation, management, and efficient utilization of plant genetic resources (pgr) (linda et al., 2009). collecting dna marker data to determine whether phenotypically similar cultivars are genetically similar would therefore be of great interest in crop breeding programs (duzyaman, 2005). evaluation of genetic diversity could be based on morphological or molecular markers. morphological features may not be efficient as they are highly influenced by environments. molecular marker technique is an efficient tool for genetic variation evaluation in plants (soares et al., 2016). consequently, the development of marker protocols such as rflp, aflp, issr, ssr and snp has revolutionized the genetic analysis by detecting level of polymorphism (raina et al., 2001). inter simple sequence repeats (issr) marker has been reported as a rapid, reproducible, and cheap fingerprinting technique based on the variation found in the regions between microsatellites (zhang et al., 2006; golkar et al., 2011). the issr method has several benefits over other techniques: first, it is known to be able to discriminate between closely related genotypes and second, it can detect polymorphisms without any previous knowledge of the crop's dna sequence (zeitkiewicz et al., 1994; mishra et al., 2014). it is a fast, inexpensive genotyping technique based on variation in the regions between microsatellites (zeitkiewicz et al., 1994). inter simple sequence repeats analyses offer breeders and geneticists with competent means to link phenotypic and genotypic variations in various fields of plant improvement (shimekt tadele et al., 2014). genetic diversity study in groundnut, based on morphological, biochemical and some molecular markers has been reported (patel and galakiya, 2014; roomi et al., 2014; peng et al., 2016; dhwani et al., 2017; zekeria yusuf et al., 2017). however, more molecular marker-based genetic diversity study of a. hypogaea accessions in ethiopia is demanding. therefore, the objective of this study initiated to determine the level and pattern of genetic variability in 43 accessions of groundnut grown in different regions of ethiopia using issr markers. mohammed et al. genetic diversity of ethiopian groundnut accessions 17 moreover, we addressed the potential in formativeness of issr markers for identifying groundnut accessions. 2. materials and methods 2.1. plant materials seeds of 43 groundnut accessions collected from different regions of ethiopia were obtained from ethiopian biodiversity institute (ebi), addis ababa, ethiopia. the accessions were previously originated from different geographical locations of ethiopia (figure 1). the seeds of all the 43 accessions were planted in plastic pots containing sandy loamy (composted) soil and maintained in a greenhouse under controlled temperature (30 °c) for about four weeks at awash melkasa agricultural research center. watering was done once a day regularly. fresh young leaves from four weeks old plants were collected from each accession in tubes containing silica gel for genomic dna extraction. gene bank number, code, collection region, locality and geographical location (latitude and longitude) of accessions are listed in table 1. figure 1. map of ethiopia showing collection sites of a. hypogaea accessions. mohammed et al. east african journal of sciences volume 16(1): 15–30 18 table 1. description of 43 a. hypogaea accessions used in the present study. s/n gene bank accession no. code * collection region locality latitude (n) longitude (e) 1 19739 gob 1 oromia/misrak/babile berkele/s 1 9o12’25.33” 42o21’26.31” 2 19740 gob 2 oromia/misrak/babile berkele/s 2 9o12’25.35” 42o21’27.34” 3 19741 gob 3 oromia/misrak/babile babile/shek a. 9o11’54.45” 42o21’41.22” 4 19742 gob 4 oromia/misrak/babile awsherit 1 9o09’21.23” 42o22’21.34” 5 19743 gob 5 oromia/misrak/babile awsherit 2 9o09’21.29” 42o22’21.28” 6 19744 gob 6 oromia/misrak/babile lecole 9o07’36.32” 42o21’02.33” 7 19745 gob 7 oromia/misrak/babile ifa gende 1 9o13’42.11” 42o18’22.18” 8 19746 gob 8 oromia/misrak/babile ifa gende 2 9o13’41.11” 42o18’22.28” 9 19747 gob 9 oromia/misrak/babile ifa gende 3 9o15’30.21” 42018’21.12” 10 19748 gob 10 oromia/misrak/babile medigana 1 9o16’06.13” 42o18’12.43” 11 19749 gob 11 oromia/misrak/babile medigana 2 9o16’06.21” 42o18’24.28” 12 19750 gob 12 oromia/misrak/babile dendaro 9o17’25.21” 42o17’25.14” 13 19751 gob 13 oromia/misrak/babile tofic 1 9o16’06.36” 42o17’36.25” 14 19752 gob 14 oromia/misrak/babile tofic 2 9o16’06.41” 42017’36.32” 15 19753 gob 15 oromia/misrak/babile berkele 9o10’48.27” 42o18’23.12” 16 19754 gob 16 oromia/misrak/babile gende 9o09’37.42” 42o18’50.10” 17 19755 gob 17 oromia/misrak/babile gemechu 9o07’25.34” 42o18’54.03” 18 19756 gob 18 oromia/misrak/babile tula 9o13’05.11” 42o19’28.32” 19 19757 gob 19 oromia/misrak/babile tula about 9o12’17.23” 42o19’38.42” 20 19758 gob 20 oromia/misrak/babile abdul 1 9o11’49.22” 42o19’43.37” 21 19759 gob 21 oromia/misrak/babile abdul 2 9o11’49.28” 42o19’58.23” 22 19760 gog 1 oromia/misrak/gursum llalemi 1 9o19’33.14” 42o26’05.26” 23 19761 gog 2 oromia/misrak/gursum llalemi 2 9o19’33.38” 42o26’05.38” 24 19762 gog 3 oromia/misrak/gursum awdal 9o18’19.23” 42o26’11.36” 25 19763 gog 4 oromia/misrak/gursum oda 1 9o19’14.11” 42o27’06.18” 26 19764 gog 5 oromia/misrak/gursum oda 2 9o18’37.42” 42o28’38.21” 27 19765 gog 6 oromia/misrak/gursum oda 3 9o18’40.13” 42o28’38.16” 28 19766 gog 7 oromia/misrak/gursum oda 4 9o18’30.32” 42o29’41.38” 29 19767 gog 8 oromia/misrak/gursum oda 5 9o18’30.28” 42o29’41.25” 30 19768 gog 9 oromia/misrak/gursum nur selam 1 9o19’30.26 42o28’38.32” 31 19769 gog 10 oromia/misrak/gursum nur selam 2 9o19’30.53” 42o28’38.45” 32 19770 gog 11 oromia/misrak/gursum odaa 1 9o21’54.13” 42o29’50.34” 33 19771 gog 12 oromia/misrak/gursum odaa 2 9o21’54.24” 42o29’50.46” 34 19772 gog 13 oromia/misrak/gursum abader 9o17’51.28” 42o24’14.33” 35 19773 gog 14 oromia/misrak/gursum harobata 1 9017’12.43” 42o23’43.24” 36 19774 gog 15 oromia/misrak/gursum harobata 2 9o17’12.38” 42o23’43.28” 37 19775 gog 16 oromia/misrak/gursum harobata 3 9o16’12.18” 42o23’18.21” 38 19776 gog 17 oromia/misrak/gursum harobata 4 9o16’22.20” 42o23’35.12” 39 19777 gog 18 oromia/misrak/gursum awdal 1 9o17’20.56” 42o26’26.65” 40 19778 gog 19 oromia/misrak/gursum awdal 2 9o17’20.48” 42o26’26.51” 41 19779 gsj -1 somalia/jigjiga beledka 9o17’51.23” 42o39’08.34” 42 24208 gaw -1 amhara/adoawe wangua 10o48’45.43” 36o25’35.12” 43 28662 gobg1 oromia/bale ginir 7o11’86.21” 40o37’46.21” note: * gog = oromia/gursum; gob = oromia/babile; gobg = oromia/bale-ginir; gsj = somalia/jigjiga; and gaw = amhara/wangua. 2.2. dna extraction dna extraction and analysis were carried out at plant molecular genetics research laboratory, department of microbial, cellular and molecular biology department, addis ababa university. about 50 mg of silica gel-dried leaves for each accession were ground with mix and miller machine. genomic dna extraction was done based on the ctab method (wang et al., 1994) with minor modification in the amount of ctab solution used (1000 μl), as well as incubation and centrifugation time, to get optimal amounts of dna. the yield of dna isolated was measured/quantified using a nano drop nd-8000 uv mohammed et al. genetic diversity of ethiopian groundnut accessions 19 spectrophotometer. moreover, the purity of dna was visually determined by agarose gel electrophoresis by running the samples on 1% agarose gel (figure 2). the samples were stored at 4 oc until subsequent analysis is carried out. figure 2. quality of the dna in 1% (w/v) agarose gels in 0.5% tbe buffer (m = molecular ladder). 2.3. primer selection and optimization for pcr optimization and screening of primers, the concentration of extracted dna from each accession were adjusted to 50 ng µl–1. a total of nine issr primers obtained from the genetic research laboratory (primer kit ubc), originally bought from university of british columbia, were used for the initial testing of polymorphism and reproducibility. all the 9 primers were screened for reproducibility and polymorphism. finally, three di-nucleotide primers (ubc810, ubc841 and ubc857), and one penta-nucleotide primer (ubc881) which showed polymorphic and reproducible bands were selected for issr amplification (table 2). table 2. issr primers screened for polymorphism and reproducibility of the amplified bands. primer annealing to (oc) sequence of nucleotides (5’–3’) amplification pattern ubc810 45 gagagagagagagagat polymorphic, reproducible ubc812 45 gagagagagagagagaa not amplified ubc824 48 tctctctctctctctcg not reproducible ubc840 45 gagagagagagagagayt not amplified ubc841 48 gagagagagagagagayc polymorphic, reproducible ubc842 45 gagagagagagagagayg not amplified ubc848 45 cacacacacacacacarc not reproducible ubc857 48 acacacacacacacacyg polymorphic, reproducible ubc881 48 ggggtggggtggggtg polymorphic, reproducible note: y = pyrimidines (c or t) and r = purines (a or g). the source was primer kit 900 (ubc 900). 2.4. issr amplification the issr amplification was done using biometra 2000 t3 thermo-cycler. the pcr amplification was carried out in a 25 μl total reaction mixture containing 50 ng μl-1 template dna, 17.5 μl ddh20, 0.5 μl dntp (1.25 mm), 2.5 μl pcr buffer (10xthermopol reaction buffer), 2.5 μl mgcl2 (2 mm), 0.5 μl primer (20 pmol μl-1) and 0.5 μl taq polymerase (5 u μl-1). the amplification program was 4 min preheating and initial denaturation at 94 oc, then 39 cycles at 94 oc for 30 sec, 1 min primer annealing at 45/48 oc based on primers used, 90 sec extension at 72 oc with a final extension of 7 min at 72 oc. the pcr products were also stored at 4 oc until loaded on gel for electrophoresis. mohammed et al. east african journal of sciences volume 16(1): 15–30 20 2.5. electrophoresis agarose gel (1.67%) was prepared using 300 ml tbe mixed with 5.01 g agarose using 500 ml erlenmeyer flask and then boiled in micro-oven for 3 minutes. after it was cooled for about 20 min at room temperature, 12 µl ethidium bromide (10 mg ml-1) was added and the gel was poured on gel casting tray to solidify. the amplified products were run on to issr gel using 1.67% agarose, with 1 x tbe using gel electrophoresis chamber. eight micro litter issr amplification products and 2µl (6x) loading dye (0.12% bromo-phenol blue and 30% glycerol) were mixed thoroughly and loaded on the gel. a 1200 bp ladder (molecular marker) was used to estimate the molecular size of the dna fragments. the gel was run on electrophoresis machine for 2 h at constant voltage of 100 v. the issr band patterns were visualized and photographed under uv light using biometra biodoc analyzer. 2.6. data scoring and statistical analysis the issr bands were scored as present (1) and absent (0) representing the issr profile of each sample. for each issr marker, total amplified bands, number of polymorphic bands, and percentage of polymorphic bands (ppb) were determined. the 0/1 matrix data was analyzed using free tree 0.9.1.50 (pavlicek et al., 1999) and ntsys-pc version 2.02 (rohlf, 2000) software to calculate the jaccard’s similarity coefficient for all possible pairs of samples. jaccard’s similarity coefficient was calculated as: cba a s ij ++ = where, sij is jaccard’s similarity coefficient, a is the total number of bands shared between individuals i and j, b is the total number of bands present in individual i but not in individual j, and c is the total numbers of bands present in individual j but not in individual i. jaccard’s similarity coefficient classified as low when its value is less than or equal to 40%, medium when it is between 40% and 60% and high when greater than or equal to 60% (stephanie, 2016). the resulting similarity matrices were employed to construct upgma-based dendrogram. the unweighted pair group method with arithmetic mean (upgma) was used in order to determine the genetic relationship among accessions using ntsyspc version 2.02 (rohlf, 2000). the matrix of genetic similarity was also used in a principal coordinate analysis (pcoa) to resolve the patterns of clustering among the accessions based on jaccard’s coefficient. percent of polymorphism, nie’s pairwise gene diversity (nei, 1987) and shannon’s weaver pairwise diversity index (i) were determined with popgene software 1.32 (yeh et al., 1997). the binary data generated were used to determine levels of polymorphism by dividing the polymorphic bands by the total number of scored bands. the shannon index varies from 0 to 1, and values closer to zero represents lower genetic diversity (silva et al. 2015). in the case of di allelic loci (binary data) the maximum value of the gene diversity (h) indices equals 0.5, revealing maximum genetic diversity (nei, 1978). according to nei (1978), gst is classified as low when its value is less than or equal to 0.05, medium when it is between 0.05 and 0.15, and high when it is greater than or equal to 0.15. in flowering plant, the level of nm is divided into three grades: high, nm greater than or equal to 1.00; moderate, nm ranging from 0.250 to 0.99; and low, nm ranging from 0.00 to 0.249 (slatkin, 1985 1987). to measure the informativeness of the issr markers to differentiate among accessions, polymorphism information content (pic), effective multiplex ratio (emr), marker index (mi) and resolving power (rp) were calculated. the value of polymorphism information content (pic) was calculated using software power marker version 3.2 (liu and muse, 2005). the pic was calculated by the formula: pic = 2pi (1-pi), where, pi is the frequency of occurrence of polymorphic bands in different priers. a pic value of less than or equal to 0.25 indicates low diversity, between 0.25 and 0.5 intermediate and value greater than or equal to 0.5 indicates high diversity (botstein et al., 1980). the emr is the product of the fraction of polymorphic bands and the number of polymorphic bands (najaphy et al., 2011). the mi was determined according to powell et al. (1996) as the product of pic and emr. the rp was calculated using the formula rp = ∑ib, where ib is band in formativeness and ib = 1-[2×(0.5-p)]; where, p is the proportion of genotypes containing the band (altıntas et al., 2008). 2.7. resolving power (rp) the resolving power (rp) is a parameter that specifies the discriminatory potential of the primers (the ability of a primer to generate optimally informative bands). many studies have indicated rp index as an important feature of a good marker system (grativol et al., 2001; mondal et al., 2008; kayis et al., 2010; sadeghi and cheghamirza, 2012). mohammed et al. genetic diversity of ethiopian groundnut accessions 21 3. results 3.1. issr polymorphism four of the nine issr primers only (table 3) produced reproducible bands ranging from 120 to 1100 bp (figure 2). fifty-six bands were generated across the four issr primers, of which 29(51.8%) were polymorphic (table 3). the amplified bands by the primers ranged from 12 (ubc841) to 18 (ubc881) across the accessions. the number of polymorphic bands of the primers ranged from 5 in primer ubc841 and ubc881 to 11 in primer ubc857. the percentage of polymorphism for primers ranged from 27.8% in primer ubc881 to 84.6% in primer ubc 857, with an average polymorphism percent of 51.8% (table 3). table 3. percent of polymorphism, polymorphism information content (pic), marker index (mi) and effective multiplex ratio (emr) and resolving power (rp) of the four issr primers in the studied groundnut accessions. primer sequence 5’–3’ annealing to (oc) total number of bands no. of polymorphic bands polymorphism (%) pic mi emr rp ubc810 (ga)8t 45 13 8 61.5 0.49 3.9 4.9 12.51 ubc841 (ga)8yc 48 12 5 41.7 0.42 2.1 2.1 10.23 ubc857 (ac)8yg 48 13 11 84.6 0.76 8.4 9.3 18.34 ubc881 (ggggt)3g 48 18 5 27.8 0.29 1.5 1.4 2.65 total 56 29 51.8 0.49 3.98 4.43 10.46 note: y = pyrimidines (c or t) and r = purines (a or g). the source was primer kit 900 (university of british colombia). in the present study, the di-nucleotide primers, namely ubc810, ubc841 and ubc857 were observed to have 61.5%, 41.7% and 84.6% of polymorphism, respectively. the penta-nucleotides primer ubc881 showed 27.8% polymorphism. a representation of the issr band profile obtained with primer ubc857 is shown (figure 3). the dinucleotide issr primers ubc857 with ac repeats and ubc810 with ga repeats, detected higher polymorphism among accessions compared with penta-nucleotide primer. figure 3. issr banding patterns generated from 43 groundnut accessions using primers ubc857. 3.2. polymorphism information content (pic) in the present study, the pic value varied from 0.29 (primer ubc881) to 0.76 (primer ubc857) with an average value of 0.49 (table 3). 3.3. marker index (mi) and effective multiplex ratio (emr) the calculated marker index (mi) value for all primers ranged between 1.5 (ubc881) and 8.4 (ubc857). the effective multiplex ratio (emr), the number of polymorphic fragments detected per assay, varied from 1.4 (ubc881) to 9.31 (ubc857) with a mean value of 4.43 (table 3). mohammed et al. east african journal of sciences volume 16(1): 15–30 22 3.4. resolving power (rp) in the present study, the estimated rp for primers varied from 2.65 (ubc881) to 18.34 (ubc857) with an average value of 10.46 (table 3). the highest rp values suggesting the capacity of the primers used to distinguish among different accessions. the rp was positively correlated with total amplified bands, number of polymorphic bands, mi and emr at p<0.01. both mi and emr were positively correlated with rp (r = 0.924 and r = 0.738, respectively, p < 0.01) and pic. 3.5. genetic diversity the lowest nei’s gene diversity (h) value (0.11) was obtained between gog-6 (gursum/oda-3) and gob10 (babile/medigana-1) and the highest value (0.38) was between gobg-1 (bale/ginir) and gob-14 (babile/ tofic-2) with a mean value of 0.245. the lowest shannon’s indices (i) value (0.24) was recorded between gog-6 (gursum/oda-3) and gob-10 (babile/medigana-1) and the highest value was 0.41 between gobg-1 (bale/ginir) and gob-14 (babile/ tofic-2) with a mean value of 0.325. the highest genetic distance values belonged to gobg-1 (bale/ginir) and gob-14 (babile/tofic-2) accessions, which were genetically the most distant accessions. the lowest observed number of alleles (na) (1.347 ± 0.433) was recorded in ‘gob14 (babile/ tofic2)’ and ‘gog6 (gursum/oda3)’ accessions and the highest observed number of alleles (1.574± 0.485) was recorded in ‘gobg1 (bale/ginir)’ accession with a mean value of 1.461 ± 0.459. the lowest values of the effective number of alleles (ne) (1.163 ± 0.316) were observed in ‘gob14 (babile/tofic2)’ and the highest values (1.328 ± 0.393) was observed in ‘gobg1 (bale/ginir)’ with a mean value of 1.245 ± 0.355. total gene diversity (ht) and gene diversity among accessions (hs) were 0.3166 ± 0.042 and 0.141 ± 0.065, respectively. the coefficient of gene differentiation (gst) among accessions was 0.294. based on the gst value, the mean estimated number of gene flow (nm) between accessions was found to be 0.827 (table 4). table 4. overall genetic variability of the studied groundnut accessions. sample size na ± (sd) ne ± (sd) h ± (sd) i ± (sd) ht ± (sd) hs ± (sd) gst nm 43 1.461 ± 0.459 1.245 ± 0.355 0.245 ± 0.095 0.325 ± 0.164 0.3166 ± 0.042 0.141 ± 0.065 0.294 0.827 note: na = observed number of alleles; ne = effective number of alleles; h = nei's (1973) gene diversity; i = shannon's information index; ht = total genetic diversity; hs = gene diversity among accessions; gst = coefficient of genetic differentiation among accessions; and nm = estimate of gene flow from gst or gcs. e.g., nm = 0.5(1 gst)/gst. for primers, the highest observed number of alleles (1.980 ± 0.640) and effective number of alleles (1.85 ± 0.12) were recorded by primer ubc857 and the least observed number of alleles (1.600 ± 0.520) and effective number of alleles (1.42 ± 0.41) were shown by primer ubc841. the highest gene diversity (0.46 ± 0.036) and shannon index (0.657 ± 0.037) was shown by primer ubc857 and followed by primer ubc810, with gene diversity and shannon index value of (0.46 ± 0.036 and 0.413 ± 0.322), respectively (table 5) and the least value of genetic diversity and shannon index was recorded by primer ubc841 with 0.25 ± 0.22 and (0.364 ± 0.326) value, respectively. table 5. overall genetic variability of issr primers used. primer na ± (sd) ne ± (sd) h ± (sd) i ± (sd) ubc810 1.643 ± 0.500 1.54 ± 0.42 0.31 ± 0.23 0.413 ± 0.322 ubc841 1.600 ± 0.520 1.42 ± 0.41 0.25 ± 0.22 0.364 ± 0.326 ubc857 1.980 ± 0.640 1.85 ± 0.12 0.46 ± 0.036 0.657 ± 0.037 ubc881 1.680 ± 0.480 1.52 ± 0.39 0.29 ± 0.21 0.419 ± 0.291 average 1.726 ± 0.535 1.58 ± 0.32 0.32 ± 0.17 0.463 ± 0.244 note: na = observed number of alleles; ne = effective number of alleles; h = nei's gene diversity; and i = shannon's information index. mohammed et al. genetic diversity of ethiopian groundnut accessions 23 3.6. genetic relationship the generated similarity matrix by issr based on the jaccard’s pairwise similarity coefficient matrices showed similarity ranged from 44% to 83%. the average similarity across the 43 accessions was found to be 63.5 %. the lowest genetic similarity value (i.e., maximum diversity) (44%) was found between accessions gobg1 (bale/ginir) and gob-14 (babile/tofic-2), followed by similarity value of 46% between gog-1 (gursum/llalemi-1) with gaw-1 (amhara/wangua) and gob-17 (babile/gemechu) with gobg-1 (bale/ginir). the highest similarity coefficient (i.e., minimum diversity) (83%) was found between the accessions gog-6 (gursum/oda-3) with gob-10 (babile/medigana-1) and gob-7 (babile/ifa-gendi-1) with gob-16 (babile /gende), followed by that between gog-12 (gursum/odaa-2) with gob-9 (babile/ifa-gendi-3) at a similarity value of 82%. 3.7. cluster analysis upgma clustering analysis grouped accessions into five clusters at cut-off point of 63.5% similarity (figure 4). the dendrogram did not divide the accessions into distinct groups based on geographical origin. the upgma analysis revealed that individuals in each accession were distributed and inter-mixed with individuals of another locality. for instance, the accessions from gursum and/or babile were distributed in all 5 distinct clusters (figure 4). moreover, accessions from distant geographical locations were clustered together with other accessions from different regions (table 6). figure 4. upgma cluster analysis of 43 accessions of a. hypogaea (gog = oromia/gursum; gob = oromia/babile; gobg = bale/ginir; gsj = somalia/jigjiga; and gaw = amhara/wangua). mohammed et al. east african journal of sciences volume 16(1): 15–30 24 table 6. clusters of accessions as shown in the dendrogram based on upgma. clusters sub-clusters accessions similarity (%) 1 1 gob (1, 2, 6,15 and 21), gobg1 and gog (11 and 13) 67 2 gob (3,7, 8, 10, and 16), gog (2,4,5,6,10,14,16 and 19) 66 2 gob (12 and 18), gsj1 and gog-9 65 3 gob (5,13 and 19) gog (3,7 and 18) 64.8 4 gob (4,9, 11 and 20), gog (8,12,15 and 17) and gaw-1 63.5 5 gob (14 and 17) and gog1 65 note: gog = oromia/gursum; gob = oromia/babile; gobg = bale/ginir; gsj = somalia/jigjiga; and gaw = amhara/wangua. 3.8. principal coordinate analysis (pcoa) all the data obtained using four issr primers were used for pcoa using jaccard’s coefficients of similarity. the first two components of the coordinates of the pcoa having eigen values of 16.3 and 8.2 with variance of 33.2% and 16.4%, respectively, and together 49.6% of the total variance. similar to the upgma clustering pattern, the 43 groundnut accessions were grouped into five groups (clusters) based on the principal co-ordinate analysis (figure 5). the pcoa plot indicated that most of the accessions did not group together with other accessions originated from the same geographical location. this result is in line with the result obtained from upgma. however, most of the accessions that show geographical proximity were found to form distinct groups and spread all over the plot (figure 5). in addition, accessions from distant geographical locations tend to form similar group. as the result, low coefficient of variation was observed among groundnut accessions considered in this study. figure 5. pcoa scatter plot diagram showing genetic relationships of a. hypogaea accessions. 4. discussion in the present study, issr profile was used to determine diversity and relationship among different groundnut accessions. several studies on populations indicated the percentage of the polymorphic locus as an important measure of genetic diversity (soares et al., 2016). groundnut showed moderate genetic diversity (p = 51.8%) as indicated by percent polymorphic loci (table 3). in the raina et al., (2001) study, the issr markers revealed 54% polymorphism among 13 a. hypogaea mohammed et al. genetic diversity of ethiopian groundnut accessions 25 accessions. in the dhwani et al. (2017) and suvendu et al. (2009) study, the issr markers revealed a higher level of polymorphism (87% and 74.7%, respectively) in groundnut. the observed highest nei’s gene diversity (h) value (0.38 ± 0.174), and the highest shannon’s indices (0.41 ± 0.194) showed presence of genetic diversity among the studied accessions. the gene diversity obtained in this study (0.38), which is relatively higher than 0.11 obtained by ren et al. (2014). on the other hand, the higher value gene diversity (0.74) was observed in the groundnut ‘reference set’ of icrisat (pandey et al., 2014). in the present study, the pic value varied from 0.29 (primer ubc881), less informative to 0.76 (primer ubc857), high informative with an average value of 0.49. pic value. pic is a statistic that measures the usefulness of a genetic marker for linkage analysis (hildebrand et al., 1992). in this study, primer ubc857 can retrieve more information on the genetic polymorphism of groundnut accessions and could be used as a genetic marker for further study. the variations in the in formativeness of the molecular markers might be due to the difference in the genetic background of germplasm collections, length of the repeat unit and type, the sequence composition and distribution or frequency throughout the genome of groundnut (dwivedi et al., 2001). thus, the choice of appropriate primer motives in issr fingerprint is critical to detect high polymorphism and reveal relationship between different groundnut accessions. the genetic differentiation of a species reflects the interactions of various evolutionary processes such as shifts in distribution, habitat fragmentation and population isolation, mutation, genetic drift, mating system, gene flow and natural selection (schall et al., 1998). possibly, these factors might have influenced the genetic differentiation of the groundnut accessions under study. the coefficient of gene differentiation (gst) for the entire accessions was 0.29 (table 4), suggesting a restricted genetic differentiation between accessions. the gst value recorded indicating about 29% of the total genetic divergence among the accessions. this might be the result of interactions of different evolutionary processes. based on the gst value, the mean estimated number of gene flow (nm) for the entire accessions was found to be 0.827 (table 4). in flowering plant, the level of nm is divided into three grades: high, nm equal to or larger than 1.0; moderate, nm ranging from 0.25 to 0.99; and low, nm ranging from 0.00 to 0.249 (slatkin, 1987). gene flow is generally considered as the main factor that could homogenize the genetic structure of populations in their distribution area. according to wright (1931), nm¼ 1 is sufficient to overcome the effects of genetic drift. also, species with low gene flow have higher genetic differentiation than species with high gene flow. however, our results indicated that virtually moderate gene flow occurred among groundnut accessions. based on jaccard’s similarity coefficient, highest levels of distance between the accessions from gobg1 (bale/ginir) and gob14 (babile/tofic2) could be attributed to the fact that the accessions have been cultivated in the respective regions over time giving enough time for significant genetic differentiation along these particular geographical lines. geographically isolated accessions could accumulate genetic differences and evolve unique traits as they adapt to different environment. differential environmental conditions with respect to soil composition, altitude and annual rainfall could drive the acquisition of local adaptations. nybom (2004) has addressed that genetic diversity is strongly associated with life form, geographic range, breeding system, seed dispersal mechanism, and successional status. on the other hand, the comparison of the genetic distances between accessions of gob10 (babile/medigana1) with gog6 (gursum/oda3), gob7 (babile/ifa-gendi1) with gob16 (babile/gende) and gog12 (gursum/odaa2) with gob9 (babile/ifagendi-3) revealed a closer genetic relationship. this high level of similarity could be due to close geographical distance among accessions and/or selecting groundnuts with similar traits by gursum and babile farmers during crop production. possible explanation for the genetic relatedness could be high rates of gene flow due to exchange of seed materials and limited time for significant genetic differentiation along geographical lines. based on issr marker, genetic relationship analysis of groundnut showed higher level of genetic similarity between groundnut genetic resources (baloch et al., 2010; dhwani et al., 2017). both pcoa and upgma cluster analysis shows the clustering of all 43 accessions into five clusters without clear geographical differentiation (figures 4 and 5). accessions from the same geographical location were distributed in various clusters. for instance, the accessions from gursum and/or babile were distributed in all 5 distinct clusters. such pattern has been reported by (raina et al., 2001; varshney et al., 2009; peng et al., mohammed et al. east african journal of sciences volume 16(1): 15–30 26 2016), suggesting that there was no significant grouping of genotypes as per geographical region in the population structure of groundnut. moreover, the present finding is consistent with studies, which addressed cultivated groundnut and reported limited genetic diversity within them (jiang et al., 2007; janila et al., 2013). accessions from distant geographical locations were clustered together. this is evident, for example, in cluster i (sub cluster i) gobg-1 accession from bale/ginir was clustered with accessions from babile and gursum. similarly, in cluster iv the accession from gaw1 (amhara/wangua) and gsj1 (somalia/jigjiga/beledka) were clustered with accessions from babile and gursum which is unexpected because they are geographically far distant locations (figure 4). this pattern is observed possibly due to admixture as the result of short and long distance marketing of groundnut seeds or exchange of germplasm across different regions (fredu nega et al., 2015; jemal yousuf and nick, 2015; addisu getahun and ermias tefera, 2017). knowledge on the genetic diversity of the selected individuals is of ultimate importance, since it contributes to the information on the species and allows the selection of genotypes to be included in future conservation programs. thus, the most divergent genotypes can be selected to maintenance the level of genetic diversity of a species to keep its ability to adapt to novel environmental changes. the present finding also contributes valuable information on the genetic diversity of groundnut accessions in ethiopia. parameters such as mi and emr have been used for assessing the informative potential of molecular markers in various genetic diversity studies (mondal et al., 2008; najaphy et al., 2011). in the present study, the primers that generated high number of bands had higher mi and emr values. both mi and emr were positively correlated with rp (r = 0.924 and r = 0.738, respectively, p < 0.01) and pic. the resolving power (rp) is a parameter that specifies the discriminatory potential of the primers (the ability of a primer to generate optimally informative bands. many studies have indicated rp index as an important feature of a good marker system (mondal et al., 2008; kayis et al., 2010; grativol et al., 2011; sadeghi and cheghamirza, 2012). many studies have indicated rp index as an important feature of a good marker system (mondal et al., 2008; kayis et al., 2010; grativol et al., 201; sadeghi and cheghamirza, 2012). in the present study, the highest rp value 18.34 (ubc-857) suggesting the capacity of the primer used to distinguish among different accessions. rp was positively correlated with total amplified bands, number of polymorphic bands, mi and emr at p<0.01, suggesting the informativeness of the issr primers used in the present study. issr markers have demonstrated their efficiency in the study of genetic variability for several other species. many studies have proved the effectiveness of this marker on genetic diversity and characterization of accessions between and within populations of capparis spinosa l. (liu et al., 2015), pitcairnia flammea (souza-sobreira et al., 2015) erythrina velutina (souza et al., 2016) and croton tetradenius (almeida-pereira et al., 2017). 5. conclusions and recommendations the study has revealed genetic polymorphism (51.8%) among the groundnut accessions. the highest genetic similarity observed among the accessions of groundnut and the observed five clusters without clear geographical differentiation suggest the existence of genetic similarity among the accessions possibly due to gene flow caused by seed exchange. the issr based fingerprinting of groundnut accessions demonstrated the usefulness of the marker in estimating the extent of genetic variation and genetic relationships among accessions. the present finding is an important milestone for future germplasm collection, sound conservation, improvement and breeding of the crop. further study with more geographic range and the use of additional molecular markers would give additional picture of the genetic 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http://dx.doi.org/10.4238/gmr.15038624 https://doi.org/10.4238/gmr.15028534 https://www.statisticshowto.com/jaccard-index/ https://www.statisticshowto.com/jaccard-index/ mohammed et al. east african journal of sciences volume 16(1): 15–30 30 ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15 (1) 25-40 licensed under a creative commons *corresponding author: dadibam@gmail.com attribution-noncommercial 4.0 international license. abundance and diversity of arbuscular mycorrhizal fungi (amf) in soils under different rangeland use types in the middle awash basin, ethiopia dawit terefe1*, zerihun belay2, fasil assefa3, kibebew kibret4, and nigussie dechassa5 1school of animal and range sciences, haramaya university, p.o. box 138, dire dawa, ethiopia 2department of applied biology, adama science and technology university, ethiopia 3department of microbial, cellular and molecular biology, addis ababa university, ethiopia 4school of natural resources and environmental sciences, haramaya university, ethiopia 5school of plant sciences, haramaya university, ethiopia abstract background: shrinking of rangelands/natural grasslands has led to various inter-communal conflicts and loss of livelihoods among pastoralists in ethiopia. restoring the rangelands is an important step to be taken to alleviate the problem. various aggressively spreading invasive weed species are threatening the existence and sustainability of rangelands/natural grasslands. in addition, moisture stress is a major hindrance to any efforts made to restore the rangeland/natural grasslands. the role of arbuscular mycorrhizal fungi (amf) in establishing plant seedlings and regenerating natural grasslands through enhancing water and nutrient uptake is well documented. objective: the main objective of this study was to investigate the influence of land use and soil types on abundance and diversity of amf in semi-arid rangeland areas of the middle awash basin in the ethiopian rift valley region. materials and methods: representative rhizosphere soil samples were taken from different land use types (cultivated, open grassland, shrubland, and prosopis-invaded land) and used to assess amf diversity and abundance in relation to soil physical and chemical characteristics. the same soil samples were used to establish trap cultures for spore formation and colonization assessment. results: in the present study, morphological analysis from field soils and trap cultures revealed 16 distinct morphotypes belonging to 10 genera including glomus (3), claroideoglomus (3), funneliformis (2), rhizophagus (2) and one from each of acaulospora, entrophospora, gigaspora, sclerocystis, scutellospora and septoglomus. spore abundance significantly varied, ranging from 265–481 and 319–488 (100-g-1) in trap culture and field soil samples, respectively. grassland soil samples displayed the highest spore abundance, followed by soil samples from shrubland and cultivated fields, with the lowest records from prosopisinvaded land use type. however, sporulation and level of colonization were higher in cultivated lands, which have lower spore abundance than open grass and shrublands. conclusion: the results of the study indicated that converting land use from traditionally managed rangelands/grazing system to cultivated lands leads to encroachment by prosopis spp. on the lands and significantly reduces amf spore abundance, diversity, and percentage root colonization. thus, the everexpanding encroachment of prosopis on the open grasslands and croplands around the awash river necessitates implementing strict measures to decrease pressure on the soil biota underneath. keywords: mycorrhizal inoculum potential; open grassland; prosopis juliflora invaded land; shrub land; trap cultures 1. introduction arbuscular mycorrhizal fungi are one of the obligate mutualistic symbionts that form association with more than 80% of the plant species in the terrestrial ecosystem (smith and read, 2010). they are known to facilitate uptake of biologically essential plant nutrients such as phosphorus (p), nitrogen (n) and other micronutrients and improve water relations under stress conditions (van der heijden et al., 1999). amf also induce plant resistance to drought stress, salt stress, give protection against pathogens and pests and reduce plant sensitivity to toxic substances in the soil (siddiqui and futai, 2008), enhance ecosystem sustainability through rapid response to degradation or any other stress (smith and read, 2010). a number of studies have documented that inoculation of amf into degraded soil improve soil structure (and accelerate the establishment of native grasses (brundrett et al., 1996; smith and read, 2010). mailto:dadibam@gmail.com dawit et al. east african journal of sciences volume 15 (1) 25-40 26 the world is currently in a period of rapid, natural and human-induced driven environmental changes brought about by land cover changes, fragmentation, invasive species, and pollution (mea, 2005). this fragmentation of natural systems leads to land degradation (ld) which is a global long-term loss of ecosystem function and productivity (naseer and pandey, 2018). land use changes in east africa have transformed natural land covers, mainly rangelands to farmlands and human settlements and urban centers at the expense of natural vegetation and loss of biodiversity (maitima, 2009). many studies have shown that encroachment into woody plant species affect soil moisture, carbon storage, soil biochemistry and biological diversity (richter and stutz, 2002; almaz kebede, 2009). the continuous land degradation can be reversed through “ecological restoration” which is the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed, and to realize the environmental and socioeconomic benefits of natural resources (hobbs & cramer, 2008). it is established that the focus on indigenous plant species in natural vegetation restoration programs could return the previous species composition within a few years (siddiqui and futai, 2008; ndoye et al., 2012). however, reseeding alone is often not sufficient in restoration of degraded natural grassland areas. one of the mechanisms that enable plants to survive in moisture-stressed environment is their ability to form a mutualistic association with soil microbes. among the soil microbes, arbuscular mycorrhizal fungi (amf) which occur in moisture-stressed environments form associations with plants and enhance water and nutrient uptake due to their rapid response to ecosystem changes (siddiqui and futai, 2008; smith and read, 2010). however, there is poor understanding of the impact of land use intensity and change on the abundance and diversity of amf in tropical soils (tachabi et al., 2008; xiang et al., 2014). in ethiopia, the arid and semi-arid rangelands covering 61-65% of the territory in the country are home to 12–15% of the human population and 26% of the total livestock population (mohammed, 2009). however, the transformation of semi-arid grassland ecosystems into human settlement and farming has caused shrinkage of grazing land, imposed high stocking rate of animals and triggered continuous land degradation and bush encroachment in the area (almaz kebede, 2009; mohammed, 2009). for instance, the middle awash areas of centraleastern ethiopia faced accelerated social and ecological change due to feed scarcity, intermittent drought, and land degradation (solomon beyene et al., 2014). over the past 30 years, there have been land use and land cover changes in the area. the change in land use was due to agricultural expansion, encroachment by aggressively spreading invasive alien plant species such as prosopis, and overgrazing (almaz kebede, 2009). accordingly, assessing the composition and status of amf species and diversity is important, as it would provide vital input for any management and restoration plans by the relevant stockholders. despite their importance, few studies to date have assessed the diversity of amf in ethiopia. most of the studies have assessed amf diversity and abundance in relation to dry woodland trees (emiru birhane et al., 2010; zerihun belay et al., 2013), coffee and shade trees (tadesse chane and fasil assefa, 2013), agroforestry and crop land ecosystems (beyene dobo et al., 2016) and high land grazing areas with terraces (emiru birhane et al., 2017). however, there is dearth of information on the diversity and abundance of amf in semiarid rangeland/grassland areas of central-eastern ethiopia, and the impact of land use change on their pattern and composition. understanding of the amf status and studying the connection between land use legacies, thus, becomes the first step to design better management and restoration strategy (sokaet al., 2015; muchane et al., 2012; emiru birhane et al., 2017). therefore, we conducted research to address the following questions. does land use type affect amf abundance and diversity in semi-arid rangelands? how do soil physical and chemical properties influence amf diversity? by answering these questions, we intended to provide a novel insight into amf diversity in semi-arid rangelands of ethiopia and how it could contribute to sustainability of rangelands/natural grassland. the information obtained can serve as a basis for designing appropriate rangeland resource management and conservation practices. thus, the aims of this study were to (1) examine the influence of land use type/cover on the diversity and abundance of amf in the middle awash basin of the ethiopian rift valley; (2) examine amf diversity, soil physical and chemical properties and their relations to different land use types in semi-arid rangeland areas of ethiopia; and (3) to examine the mycorrhizal inoculum potential (mip) of the soils from different land use types. 2. materials and methods 2.1. description of study area the study was conducted in four land use types in the middle awash basin of the ethiopian rift valley (figure 1). the basin is located at 90o 16’ n and 400o 9’ e, and categorized as semiarid rangeland with altitude ranging from 500–752 meters above sea level (chekol and mnaluk, 2012). the rainfall is bimodal with mean annual rainfall of 277–653 mm with the main rainy season extending from july to september, and short rainy season from february to april. the mean daily minimum and maximum temperatures are 18 and 34 oc, respectively (tessema zewdu et al., 2012). the mean annual total evaporation ranges from 1810 to 2348 mm. the soils of middle awash basin are derived from an alluvial (deposition of streams) and dawit et al abundance and diversity of arbuscular mycorrhizal fungi 27 colluvial process (weathering of bedrock materials) associated with fluvial process at one time or another (wondimagegne chekol and abere minalu, 2012) figure 1. map of the study area and sampling locations. there are three land uses, namely, protected area (awash national park), large-scale irrigation farming and traditional use by the indigenous pastoral and agro-pastoral communities. in addition, vast areas of grazing land have been seriously encroached by the invasive plant prosopis juliflora (almaz kebede, 2009). table 1. geographical positioning and description of study sites. land use a location altitude dominant plant species ogl 08o54’15.2” n 040o04’32’.1” e 1040 m.a.s.l. cenchrus ciliaris, cenchrus setigerus, chrysopogon plumulosus, ischaemum afrum ocimum canum, panicum coloratum, sporoblus ioclades, pil 09o17’57.2”n 040o16’42.5” e 960 m.a.s.l. acacia senegal, prosopis juliflora, sporob ioclades, cl 08o54’26.7”n 039o53’52.5” e 1022 m.a.s.l. sorghum, maize and onion sl 08o51’42.7”n 040o02’09.1” e 808 m.a.s.l. acacia melifera, acacia senegal, chrysopogon plumulosus, dobera glabra, grewia bicolar, note: a ogl = open grassland; pil = prosopis-invaded land; cl = cultivated land; and sl = shrubland; m.a.s.l = meters above sea level. 2.2. experimental design fieldwork was conducted in october 2018 after the end of the long rainy season in the middle awash basin of the ethiopian rift valley system. soil samples were collected from four land use types, namely; open grass, shrub, prosopis invaded and cultivated lands. a total of 24 samples (4 land use type x six replicates of soil samples from each land use) were collected at a depth of 0–20 cm. 2.3. soil sample collection six replicates of sampling points (25m apart) were established for each land use type and soil samples were collected at the depth of 0–20 cm. the six soil samples from a land use were mixed and a composite soil sample was drawn. the samples were sealed in sterile polyethylene bags, transported and stored at 4°c in a refrigerator for further studies. composite soil sample from each land use was partitioned into three sets of sub samples. the first set of soil sample was used to establish bioassays; the second set of soil sample was used for amf spore analysis; the third set of soil sample was used to analyze soil physicochemical properties. 2.4. analysis of soil physical and chemical properties soil physical and chemical properties were analyzed following standard procedures. soil texture, ph, total n, available phosphorus (p), and soil organic matter (om). soil texture was determined using bouyoucos’ hydrometer method (day, 1965). soil ph was measured dawit et al. east african journal of sciences volume 15 (1) 25-40 28 by glass electrode in a 1:2.5 soil: water suspension (ziadin, 2007). total n was determined by kjeldahl method following the procedure described by hinds and lowe (1980). available phosphorus (p) was extracted with a solution of 0.5 m nahco3 at ph 8.5 (olsen and sommers, 1982). soil organic matter (om) was analyzed using the dichromate oxidation method (walkley and black, 1934). 2.5. establishment of trap culture trap cultures were established from fresh field soils collected from the four land use types to induce sporulation of fungi present in the soil. composite soil samples containing root fragments from each land use type were mixed with autoclaved sand (1:1; v/v) and accommodated in 15cm plastic pots to serve as a substrate. five surface-sterilized (using 0.5% sodium hypochlorite solution for 15 minutes) sorghum seeds (sorghum bicolor) were sown in each pot (three pots per land use type) and thinned down to three after establishment. they were placed in a greenhouse in completely randomized design under natural light condition; mean morning/midday/night temperatures of 15/30/21oc and watered daily as needed. watering was reduced during the final weeks to maximize spore production. at the end of 4 months, the plants were cut near the base, and the cultures were air dried and checked for the presence of spores. 2.6. determining mycorrhizal inoculum potential (mip) of the soil bioassay was performed to determine mycorrhizal inoculum potential of soil samples from different land use types according to brundrett et al. (1996). thus, 400g of soil samples with root fragments were put into plastic pots. sorghum (sorghum bicolor) seeds were surface sterilized and sown as before on five pots per land use type and they were then thinned down to one per pot after emergence and placed in a greenhouse in completely randomized design under natural light condition for 45 days. roots were harvested and preserved in 50 % ethanol and stored at 40c for further assessment of root colonization. 2.7. root staining and quantification of amf root colonization roots were washed carefully with tap water and cut into segments of about 1 cm long and put in a test tube (15 ml) containing 10% (w/v) koh and heated at 90°c in a water bath for 1 hour to be bleached. thereafter, the roots were washed to remove the koh and treated with 10% hcl (v/v) for 15 min at room temperature and finally stained in 0.05% w/v trypan blue in lactoglycerol (1:1:1 lactic acid, glycerol and water) at 90°c for 30 min in a water bath (brundrett et al., 1996). fungal colonization was quantified using the magnified intersection method (mcgonigle et al., 1990) under a compound-light microscope at a magnification of x 200. thus, 100 root segments were mounted on microscope slides to examine the presence and percentage colonization of amf structures; hyphae, arbuscule, and vesicle. 2.8. amf spore extraction and identification amf spores from field soil and trap cultures were isolated using the wet sieving and decanting method (gerdemann and nicolson, 1963), followed by sucrose gradient technique (brundett et al., 1996). hundred grams of dry soil sample was soaked in 1000 ml water and left for 5 minutes to settle soil particles and was decanted through 500 µm, 250 µm, 100 µm and 45 µm sieve layers. the contents left in 250–45μm sieves were collected in a test tube and suspended in water and centrifuged at 2000 rpm for five minutes, and the supernatant was decanted. the soil materials in the test tubes were re-suspended in a 50% sucrose solution and centrifuged at 2000 rpm for one minute. then, the supernatant containing the spores was poured over a 45-μm size sieve and washed with tap water thoroughly to remove the sucrose and transfer the spores to a petri dish. the amf spores were counted under a dissecting microscope (iso 1006) at x4 magnification. enumeration of spore numbers per gram of dry soil was undertaken according to invam, http://invam.caf.wvu.edu. thereafter, healthy looking spores with similar morphology were picked and mounted on slides in polyvinyl-lactic acid-glycerol (pvlg) or in pvlg mixed with melzer’s reagent (1:1 v/v), and examined under the compound microscope [novex holland] at x400 – 1000 magnification (brundett et al., 1996). species identification and matching of morphotypes were based on original descriptions and identification manuals of schenck and perez (1990), online references of species descriptions provided by invam (2004) (http://invam.caf.wvu.edu), west virginia university, usa, university of agriculture in szczecin, poland (http://www.zor.zut.edu.pl/glomermycota), schüßler and walker (2010) and the schüßler am fungi phylogeny website (http://www.lrz.de/~schuessler/amphylo/). 2.9. amf diversity and density spore abundance of arbuscular mycorrhizal fungi was expressed as the number in 100 g soil. isolation frequency (if): number of samples in which a given species was observed as the percentage of total soil samples for each land use type, relative abundance of spores (ra) and the importance value (iv) were calculated to determine the dominance or rarity of amf species. diversity of am fungi among the land use types was determined using the shannon wiener diversity index (h') calculated by the formula: h'= ∑ (p𝑖 ln p𝑖 ) k i=1 dawit et al abundance and diversity of arbuscular mycorrhizal fungi 29 where, pi= the proportion of individuals in the ith species and ni = the number of species with i individuals. pielous’ evenness index was also used to measure species evenness (j) using the formula j = h/log(s): where, h = observed shannon index; s= total number of species in the habitat. the simpson dominance index (d) was calculated using the formula: d = 1/ ∑(𝑛𝑖 / n) 2 𝑆 𝑖=1 : where, ni = the total number of individuals in a species i; n is total number of species in the sample and s is the number of species. 2.10. data analysis pearson correlation coefficient was performed to figure out the relationship between amf root colonization, spore density (sd), richness (r) and soil parameters. significant differences among land use types in sd, r and soil parameters were examined using one-way anova while mean separation was done using tukey’s hsd multiple comparison test at p values < 0.05. all statistical analyses were performed using r 3.6 software. 3. results 3.1. land use and soil physicochemical properties the soil physical and chemical analyses showed that all land use types have a loamy soil textural class. the soils are alkaline ranging from 7.67 for shrub land (sl) to 8.84 for ogl land use type). soil organic carbon and total nitrogen content were significantly higher in grazing areas (ogl & sl) than in cl and pil land use types (table 2). the data also showed that cultivated land (cl) contained significantly higher available p (25.6 ± 0.35) and k (117.37 ± 0.55) content compared to the others. table 2. physical and chemical properties of experimental soils in four different land use types of the middle awash basin, ethiopia. soil parameter land use type open grassland prosopis invaded cultivated land shrub land f value p value ph 8.84 a ±0.05 8.52ab ±0.23 7.87 bc±0.05 7.67 c ±0.05 55 0.000 ec dsm-1 0.51b ± 0.01 1.21 a ± 0.02 0.33 c ± 0.02 0.31 c ± 0.01 2816 0.000 oc % 2.7a ± 0.04 1.91b ± 0.02 2.10b ± 0.12 2.35ab± 0.31 14.77 0.001 tn (%) 0.18ab ± 0.04 0.13c ± 0.01 0.17 b ± 0.00 0.20 a ± 0.00 50.65 0.000 c/n 15.1a ± 0.36 15.3a ± 1.88 12.62ab ± 0.52 11.97b ± 1.5 5.628 0.022 p (mg/kg) 6.27 b ± 0.03 5.85 b ± 0.79 25.62a ± 0.35 1.44 c ± 0.01 1888 0.000 ca 22.10a ± 0.63 12.04b ±1.49 9.57c ± 0.02 11.36b ±1.03 382.4 0.000 mg 4.41b ± 1.11 4.86a ± 1.03 3.82c ± 0.83 4.8ab ± 0.62 26.16 0.0001 na 1.46a ± 1.93 0.37c ± 0.52 0.52b ± 0.47 0.42c ± 0.01 1325 0.000 k (mg/kg) 82.97c ± 0.48 95.14b ±0.15 117.37a ±0.55 62.73d ± .61 6733 0.000 cec 25.12a ± 0.83 18.57b ±0.40 15.62c ± 0.37 16.99bc±0.04 214.8 0.000 sand (%) 54.3 d ± .58 58.2 c ± .06 68 a ± 1.00 62.1 b ± .08 304.3 0.000 clay (%) 31a ± 0.00 19.2b ± 0.61 13.3d ± 1.53 17.7c ± 1.15 169.4 0.000 silt (%) 15.33d ± 0.58 23.61a ±0.51 19.2bc ± 0.26 21.17 b± .21 289.8 0.000 note: aca, mg, na in cmolc/kg; c/nc = ratio; cec in meq/100g; means in the same row followed by same letter do not differ significantly at p < 0.05 probability level. 3.2. amf root colonization the percentage hyphal, arbuscular, and vesicular colonization on the sorghum plant established on soils from the four land use types ranged from 18.6% 34%, 1.6%–5.0% and 0.6%-3.7%, respectively (table 3). the land use types also showed different patterns of amf structural distribution. cultivated land displayed the highest percentage of hyphal (34%) and arbuscular (5.0%) colonization while shrub land showed the highest vesicular colonization (3.7%) on the roots of sorghum plants. there were significant differences in levels of hyphal and vesicular colonization. however, post hoc tukey’s hsd test did not show significant difference (p = 0.25) in hyphal colonization level between ogl and sl. dawit et al. east african journal of sciences volume 15 (1) 25-40 30 table 3. mean percentage colonization of mycorrhizal structures in samples of roots from sorghum trap plant (mip across land use types). land use type percentage of colonization arbuscules vesicles hyphae open grass land (ogl) 3.0 ± 2.6 1.7 b ± 0.6 25.6 bc ± 2.3 prosopis invaded land (pil) 2.3 ± 1.0 0.6 b ± 1.2 18.6 c ± 4.2 cultivated land (cl) 5.0 ± 2.64 2.7 ab ± 0.5 34 a ± 3.1 shrub land (sl) 1.6± 2.1 3.7 a ± 2.1 29 b ± 4.0 f = 2.02; p = 0.19 f = 8.57; p = 0.007 f = 2.02; p > 0.05 note: means followed by different letters in each column denote significant difference at p < 0.05. 3.3. amf spore density in field soils and trap cultures the data showed ogl displayed the highest mean spore count (488 ± 8.5) while, cl land contained the lowest (319 ± 5.1) mean spore count per 100g of field soil (figure 2). the impact of land use types on amf spore density was significant (f = 15.6, p<0.05). sporulation in amf was variable amongst the land use types where ogl and pil induced a smaller number of spores with trap cultures and cl and sl contained more spores than their respective from field soils. in fact, no significant (f = 0.001, p = 0.97) difference was observed in the overall spore density between trap culture and field soil from different land use types. the number of spores recovered from trap culture from sl and cl were 14.3% and 25.8% higher than their respective field soil, respectively (figure 2). however, trap cultures established from ogl and pil soils were not efficient and number of amf spores recovered were 25% and 28.1% less than the field soil, respectively. figure 2. amf spore density in field and trap culture. the data did not show significant correlation between spore abundance and the occurrence of mycorrhizal structures [hyphal (r = 0.19, p = 0.53), arbuscular (r = –0.14, p = 0.66) and vesicular (r = 0.33, p = 0.28)] colonization percentages. the pearson correlation coefficient showed that amf spore density from field soil was correlated to tn (r = 0.8, p< 0.05), cec (r = 0.63, p< 0.05), ca (r = 0.71, p< 0.05), na (r = 0.72, p< 0.05) and oc (r = 0.86, and p< 0.05) of the soil characteristics. however, spore density did not show any correlation with and soil p, ph and mg content (table 4). spore density in trap culture was not correlated to most of the parameters except soil total nitrogen content (r = 0.88, p< 0.05). dawit et al abundance and diversity of arbuscular mycorrhizal fungi 31 table 4. correlation between amf spore density [100 g–1] and some soil parameters in different rangeland use types in the middle awash basin, ethiopia. soil parameter spore density (sd) field soil trap culture r p value r p value ca 0.71 0.00 -0.19 0.55 cec 0.63 0.02 -0.30 0.33 mg 0.87 0.05 -0.33 0.28 na 0.72 <0.05 -0.01 0.95 n/c -0.08 0.79 -0.75 <0.05 p -0.39 0.6 0.16 0.83 ph 0.13 0.68 -0.71 <0.05 tn 0.78 <0.05 0.88 <0.05 k -0.65 0.02 -0.27 0.37 oc 0.86 <0.05 0.34 0.26 ec -0.58 0.04 -0.95 <0.05 sand -0.45 0.13 -0.52 0.08 clay 0.68 0.01 -0.265 0.404 silt -0.72 <0.05 -0.263 0.408 other soil physical properties such as k, ph, ec, n/c, and silt also indicated negative relation with spore density, while soil clay content had significant positive correlation (r = 0.68, and p< 0.01) with spore density in field soil, but sand content was negatively correlated to amf spore density in trap culture. 3.4. amf species composition in different land use types in the present study, morphological analysis from field soil and trap culture revealed the presence of 16 distinct morphotypes, belonging to 10 genera (acaulospora, claroideoglomus, entrophospora, funneliformis, gigaspora, glomus, rhizophagus, sclerocystis, scutellospora and septoglomus) (table 5). four of the morphotypes (acaulospora, glomus species 1& 2 and entrophospora) could not be identified to species level. the genus glomus represented the most abundant group accounting for 33.6% of the total genera, followed by claroideoglomus (23.4%), and funneliformis (20.5%). the remaining 6 genera account for 22.5%, of the morphotypes and two morphotypes: belonging to gigaspora and entrophospora constituted to less than 1% of the total genera. with regard to species diversity, the dominant genus glomus included three species; but only one morphotype (glomus hoi) was identified at the species level. similarly, the genus claroideoglomus contained three species including claroideoglomus claroideum, claroideoglomus etunicatum and claroideoglomus lutum. two genera funneliformis and rhizophagus contained two species (funneliformis mosseae, funneliformis geosporum and rhizophagus aggregatus, rhizophagus fasciculatus, respectively). table 5. relative abundance of amf genera in field soil and trap culture of the different rangeland use types in middle awash basin, ethiopia. amf genera trap culture field soil total sd ra sd ra sd ra acaulospora 24 5.43 23 4.90 47 5.16 claroideoglomus 109 24.66 104 22.17 213 23.38 funneliformis 96 21.72 91 19.40 187 20.53 gigaspora 4 0.90 0.00 4 0.44 glomus 138 31.22 168 35.8 317 33.6 entrophospora 0.00 3 0.64 3 0.33 rhizophagus 11 2.35 1.21 sclerocystis 28 6.33 31 6.61 59 6.48 scutellospora 20 4.52 19 4.05 39 4.28 septoglomus 23 5.20 19 4.05 42 4.61 note: sd = spore density per 100 g-1 soil and %ra = relative abundance. dawit et al. east african journal of sciences volume 15 (1) 25-40 32 the data also showed that the most frequently isolated amf species in field soil and trap culture samples of all land use types (100%) were calarodium caloradum, funuliform mossae and glomus sp. 2. the other frequently isolated from three of the four land use types (75%) amf were, acaulospora sp., glomus sp.1, and sclerocystis sinuosa. the other morphotypes such as septoglomus constrictum, scutellospora pellucida, and claroideoglomus lutum were isolated from two of the four land use types. the isolation frequency of the three top amf species: claroideoglomus claroideum, funueliformis mosseae and glomus sp. 2 from trap culture were 31%, 30.6%, 30.0%, respectively, whereas claroideoglomus claroideum (30%), funueliformis mosseae (33.3%) and glomus sp.1 (29.3%) were the most frequently isolated species from field soil samples (table 6). on the basis of importance value (iv), three amf species, funneliformis mosseae (57.6), claroideoglomus claroideum (56.8), and glomus sp.1 (50.4) were dominant in the field soil samples. similarly, three species claroideoglomus claroideum (60.6), funneliformis mosseae (59.2) and glomus sp. 2 (57.6) were dominant in trap culture. five species and three species were categorized as common species in field soil and trap culture, respectively. of the fourteen species isolated from field soil samples, four species were categorized as rare of which rhizophagus fasciculatus. rhizophagus aggregatus, glomus hoi, and entrophospora sp. failed to appear in trap culture. interestingly, glomus spp.1 which was dominant in field soil became common in trap culture, while, glomus spp. 2 which was common in field soil become dominant in trap culture. 3.5. amf richness and diversity amf species richness in field soil was in the range of 5 –11. the highest mean am fungi species richness per field soil sample was recorded for ogl, followed by sl, fl and pil (table 7). however, in the case of trap culture, the highest mean am fungi species richness per field soil sample was recorded in sl (10), followed by cl, ogl and pil. the lowest number of morphotypes (5) was recorded from pil use type. the number of morphotypes in field soils of ogl and pil use types decreased in number compared to their trap culture counterpart. for instance, four amf species (rhizophagus fasciculatus, glomus hoi and entrophospora from ogl and rhizophagus aggregatus from cl field soils) failed to appear in their respective trap cultures. however, two new morphotypes, gigaspora gigantica and funuliform geosporum, were recovered from trap cultures of cl and sl land use types, respectively. the amf claroideoglomus etunicatum was isolated only from sl field soil and trap culture samples. http://amf-phylogeny.com/species_infos/higher_taxa/schuessler+walker%20(2010)%20glomeromycota%20species%20list%20with%20new%20taxa.pdf http://amf-phylogeny.com/species_infos/higher_taxa/schuessler+walker%20(2010)%20glomeromycota%20species%20list%20with%20new%20taxa.pdf dawit et al abundance and diversity of arbuscular mycorrhizal fungi 33 table 6. isolation frequency, relative abundance and important value of amf in field soil samples. amf species trap culture field soil if ra iv status occur if ra iv status occur acaulospora sp. 8.00 19.3 13.7 com cl, ogl 7.67 18.9 13.9 com cl,ogl,sl claroideoglomus claroideum (schenck and smith,2010) 31.0 88.6 60.6 dom all 30.00 81.1 56.8 dom all claroideoglomus etunicatum (becker and gerdemann; walker and schussler, 2010) 3.00 6.5 4.7 rare sl 3.00 7.1 5.2 rare sl claroideoglomus lutum (stutz and morton; walker and schüßler, 2010) 2.67 8.9 5.8 rare ogl, pi 1.67 3.2 2.5 rare ogl, pi funneliformis geosporum (nicolson and gerdemann; walker and schüßler, 2010) 1.67 3.6 2.6 rare sl funneliformis mosseae (nicolson and gerdemann; walker and schüßler, 2010) 30.66 86.1 59.2 dom all 30.33 82.1 57.6 dom all gigaspora gigantea (nicolson and gerdemann; gerdemann;and trappe, 1974) 1.33 3.3 2.3 rare pi rhizophagus aggregatus (schenck andsmith.1982) 2.00 5.7 4.1 rare cl rhizophagus fasciculatus (gerdemann andtrappe,1974) 1.67 3.2 2.5 rare ogl glomus hoi (berch andtrappe, 1985) 3.00 5.8 4.5 rare pi glomus sp.2 30.00 79.6 57.6 dom ogl,cl,pi 24.00 62.3 43.7 com all glomus sp.1 17.33 44.1 29.7 com ogl,cl,pi 29.33 68.1 50.4 dom cl,ogl,sl entrophospora sp. 1.00 1.9 1.5 rare ogl sclerocystis sinuosa (gerdemann and bakshi, 1976) 9.33 28.6 19.0 com ogl,cl,sl 10.33 26.8 18.9 com ogl,pi,sl scutellospora pellucida (nicolson and schenck; walker and sanders, 1986) 6.67 23.2 14.9 com cl,sl 6.33 20.1 13.6 com pil,cl septoglomus constrictum (silva and oehl, 2011) 7.67 18.5 13.1 com ogl, sl 6.33 13.5 10.2 rare ogl, sl note: cl = cultivated land, ogl = open grassland, pi = prosopis invaded land, sl = shrubland, if = isolation frequency, ra = relative abundance, iv = importance value, occur = occurrence, dom = dominant, and com = common. http://amf-phylogeny.com/species_infos/higher_taxa/schuessler+walker%20(2010)%20glomeromycota%20species%20list%20with%20new%20taxa.pdf dawit et al. east african journal of sciences volume 15 (1) 25-40 34 however, two new morphotypes, gigaspora gigantica and funuliform geosporum, were recovered from trap cultures of cl and sl land use types, respectively. the amf claroideoglomus etunicatum was isolated only from sl field soil and trap culture samples. figure 3. some amf species identified form the samples: a) claroideoglomus claroideum b) entrophospora nevadensis c) septoglomus constrictum d) gigaspora gigantea e) rhizophagus aggregatus; f) glomus species (brown) g) glomus hoi h) glomus spp. (red brown; thick wall) i) calarodium ethonicatum. furthermore, ecological measures of diversity such as species richness, simpson dominance, shannon and pielou indices showed variation of amf species among land use types (table 7). the data showed that the highest amf species richness was recorded from ogl with shannon weiner diversity index of h’= 2.1, and the lowest species richness for pil (h’= 1.51) from field soil. table 7. species richness, shannon and pielous evenness indices of amf in different rangeland use types of the middle awash basin, ethiopia. land use richness shannon h’ simpson d evenness j field trap field trap field trap field trap open grass land (ogl) 11 7 2.16 1.83 0.87 0.82 0.90 0.94 prosopis invaded land (pil) 5 5 1.51 1.54 0.75 0.77 0.94 0.96 cultivated land (cl) 7 8 1.87 1.89 0.84 0.83 0.96 0.91 shrub land (sl) 8 10 1.92 2.08 0.84 0.85 0.93 0.91 dawit et al abundance and diversity of arbuscular mycorrhizal fungi 35 nevertheless, in the case of trap cultures the result was vice versa; soil samples from sl land use type showed the highest amf species richness with shannon weiner diversity of h’= 2.08, followed by ogl (h’= 1.83). 4. discussion 4.1. amf spore abundance in field soils and trap cultures the average amf spore density from field soil and soil culture showed significant variation across land use types differing in vegetation cover and intensity of use. the difference in the average amf spore density was in the range of 319 in pil and 488 in the ogl per 100g of soil (figure 2). spore densities were higher in less disturbed natural ecosystems than in disturbed ones (cultivated and invaded). this is similar to the report that indicated the conversion of semi-arid rangeland to other land use type decreases amf spore abundance because of the sensitivity of amf to soil biochemical changes (guo et al., 2008). alien species encroachment or change in vegetation (from ogl to pil or sl) alters amf spore density and infectivity potential. the amf spore count recorded in this study was lower than the mean spore count of 994 per 100g soil according to zerihun belay et al. (2013) who reported their study results on a similar environment in central ethiopia. in fact, 4790 spores per 100g of soil was reported from different land use types in the semi-arid area of senegal near to serengeti (soka et al., 2015). however, 35–130 spores per 100g of soil were reported from different land use types of the semi-arid taita-tavveta district in kenya (jefwa et al., 2012); from semiarid wooded grassland in western ethiopia (yonas yoannes and fasil assefa, 2007) and from soils of grazing areas of northern ethiopia (emiru birhane et al., 2017) also reported 58 and 176 spores per 100g soil; mean spore count 13.6 per 100g soil was also reported from different land use types in kenya (muchane et al., 2012) in this study, spore yield was variable, and there was no correlation (r = 0.19, p = 0.53) between field soil spore density and amf sporulation in the culture. trap cultures established from cl and sl were better and produced more spores compared to those from field soils of the same land use types. however, sporulation of am fungi is soils form ogl and pil inv were poor and produced fewer spore than those from field soils of the same land use types. interestingly, a soil from cl showed the lowest spore abundance next to pil, but rate sporulation and level of colonization was far better than ogl and sl areas (figure 2). the high sporulation rate in trap cultures from cl may be attributed to adaptability of amf in cl which has been accustomed to different farming disturbances or implies irrigation water used for cultivation was stressful to amf sporulation than the tap water used in the greenhouse; whereas lower sporulation rate in pil may also be due to the loss of host plants or host plant specificity (smith and read, 2008; muchane et al., 2012). 4.2. amf root colonization in this study arbuscular mycorrhizal infectivity potential varied across land sue types (table 3). the percentage of hyphal root colonization in the present study was between 18.6 and 29% (table 3). the lowest colonization value was recorded from soil samples of pil and the highest colonization was from cl. the percentage root colonization was similar to the ones reported from various land use types in ethiopia (19.4% – 53.7%) (zerihun belay et al., 2015) and in sorghum trap culture in kenya (18.8% – 45%) (muchane et al., 2012) although, soil from cultivated land (cl) displayed the highest level of mycorrhizal infectiveness in sorghum bioassay, it actually harbored lower number of spores than ogl and sl land use types. these findings are consistent with other reports in which infectivity of soil from cl showed the highest mycorrhizal colonization levels (zerihun belay et al., 2015), particularly in low input monocropping farming systems (muchane et al., 2012). however, there were contrasting reports by beyene dobo et al. (2016), and jefwa et al. (2012). pearson correlation analysis revealed that no significant correlation existed between amf spore density and percentage of hyphal and vesicular colonization, which is consistent with other reports (beyene dobo et al., 2016; zerihun belay et al., 2015). 4.3. relationship between amf spore abundance and soil physicochemical properties this study showed a relation between land use types and the soil physicochemical properties (table 2). pearson correlation coefficient showed that amf spore abundance showed significant positive correlation with soil oc, ca, na and tn (table 4) but not with p, n/c and ec. thus, the observed variation in this study might be due to other edaphic or environmental factors (jefwa et al., 2012; soka et al., 2015). amf spore density showed no significant correlation with sand and clay contents of field soil. root colonization showed significant negative correlation with silt content in field soils (table 4). hyphal colonization showed significant positive correlation with vesicular colonization (table 8). in contrast, arbuscular colonization had no significant relationship with vesicular (r = 0.2, p = 0.53) and hyphal colonization (r = 0.33; p = 0.28). this result is in line with zerihun belay et al. (2015). no significant correlation was observed between spore abundance and percentage colonization by mycorrhizal structures [hyphal (r = 0.19, p = 0.53), arbuscular (r = -0.14, p = dawit et al. east african journal of sciences volume 15 (1) 25-40 36 0.66) and vesicular (r = 0.33, p = 0.28)] in field soils (table 8). in contrast, in trap culture, the spore abundance was positively correlated with vesicular (r = 0.84, p<0.05) and hyphal (r = 0.81, 0.001) colonization. table 8. pearson correlation coefficient between amf spore abundance and colonization (%). parameters arbuscules vesicles hyphae r p r p r p amf spore abundance in field soil -0.14 0.660 33 0.28 .19 0.53 amf spore abundance in trap culture 0.13 0.665 0.84 <0.05 0.81 0.001 arbuscules --0.20 0.52 0.33 0.28 vesicles ----0.64 0.02 4.4. amf composition simpson dominance index values similarity analysis showed difference in amf species composition, where the highest index of dominance for amf in sl as compared to the other land use types indicates lower number of shared dominances of amf species. however, the lowest simson index values [(0.75) in field soil and (0.77)] in trap culture from pil land use type showed higher number of shared dominance (uniformity in the abundance of species) than the other land use types. the highest j values 0.96 and 0.94 in filed soil samples of cl and pil show uniform distribution of species, which indicated how cultivation and encroachment by invasive plants negatively affect rare amf spp. composition. other studies also showed that land use cover and management have a strong impact on am fungi morpho types by modifying their composition and pattern (ndoye et al., 2012; xiang et al., 2014). the diversity study showed that the amf were diversified into nine genera and sixteen species (table 5, 6). some of the species identified in the field were not recovered in the trap culture. funneliformis, claroideoglomus, and glomus were the dominant genera that were also reported by other researchers from ethiopia (beyene dobo et al., 2016; zerihun belay et al., 2015) and kenya (muchane et al., 2012 and tachabi et al., 2008). of the 14 spp. identified in the field soil, funneliformis mosse, claroideoglomus claroideum, glomus spp 2 were distributed in all land use systems and categorized as generalists, whereas four species rhizophagus fasciculatus (4.5) rhizophagus aggregatus (4.0%), glomus hoi (2.5%), and entrophospora (1.5%) were described as rare species. however, the three species: claroideoglomus claroideum, funneliform mosse and glomus sp. 2, showed high isolation frequency (59.3, 58 and 54.0%, respectively) in trap culture. this phenomenon shows their capability to sustain in the prevailing biotic and abiotic change in the region, as well as their potential to adapt to new environmental conditions. thus, these species could be selected as candidates for inoculum development initiative. 4.5. am richness in this study, the highest amf richness was observed in ogl followed by sl; while relatively lower and lowest values were recorded for cultivated land and pil, respectively. two new species were recovered in the trap culture soil but not in field soils; and some species, which were recorded in field soils failed to appear in trap culture. for instance, four species failed to appear in trap culturewhereas two new species were identified in this study. the result suggested that different environmental and management conditions in the field and greenhouse might be the cause for the absence and presence of am spores between field soil and trap culture samples as reported earlier by xiang et al. (2014) and leal et al. (2018). in fact, many studies have indicated higher proportion of amf sporulating under field conditions were unable to sporulate under greenhouse conditions (antoniolli et al., 2002; muchena et al., 2012). this phenomenon emphasizes the need for trap culturing and subsequent isolation of spores to reinforce amf species survey obtained by direct isolation from field soils (brundrett et al., 1996; siddiqui and futai, 2008). amf species richness recorded in this study was lower than that reported by other studies conducted in semi-arid areas worldwide; 43 recorded in brazil (sturmer and siquueira, 2011), 42 in different land use types in ethiopia (zerihun belay et al. 2015) and 29 under different plant and soil properties in southern ethiopia (beyene dobo et al. 2016). nonetheless, the species richness was comparable to other studies from tropical regions elsewhere in the world. soka et al. (2015) recorded 9 species in the serengeti ecosystem, tanzania; jefwa et al. (2012) reported species richness of 12 from seven land use types in kenya; antoniolli et al. (2002) reported 12 from different land use types in southern australia. the differences may be attributed to sampling intensity (brundett et al., 1996), isolation technique (leal et al, 2018) and identification methods (smith and read, 2010). moreover, the large variation in spore density and species richness of amf in different rhizosphere can be attributed to other factors such as soil disturbance (tachabi et al., 2008), ecological degradation (muchena et al., 2012) complex dawit et al abundance and diversity of arbuscular mycorrhizal fungi 37 underground structure (van der heijden et al., 1999), and host-preference (antoniollil et al., 2002). 4.6. amf species diversity the variations in shannon wiener diversity index observed in this study reflect the substantial impacts of land use type on amf diversity. open grassland harboring highest number of amf species as compared to the other land use types had higher h’ value. actually, traditionally managed ecosystems (ogl and sl) showed higher species diversity in field soil samples, respectively; whereas in trap cultures the higher h’ values were recorded in sl and cl, respectively (table 7). leal et al. (2018) showed that land use type and condition have enormous impact on amf diversity in field soil as well as in trap culture. amf diversity in areas where there is less human and animal interference shows higher richness and diversity. the relatively higher amf species richness and shannon weiner diversity (h’= 2.16 and 1.96, respectively) observed in ogl and sl than in cl and pil could be taken as an evidence to support the argument. soil disturbance caused by cultivation and overgrazing followed by invasion negatively affected amf diversity. lower shannon weiner diversity indices were recorded in pil and cl lands. the high available p and tillage practice (smith and reads, 2010; xiang et al., 2014) might be the cause for the lower amf diversity in cl land use type; whereas in pil, overgrazing coupled with degradation followed by prosopis invasion or land use change (from open grass land to thick shrubland) could be the cause for the lower am fungi diversity (siddiqui and futai, 2008; xiang et al., 2014). 5. conclusion this study has demonstrated that the arbuscular micorrhizea (amf) community structure of the four land use types in semi-arid soils of middle awash basin is variable and mainly characterized by low abundance and diversity. however, the results revealed that open grassland and shrub land, which have been managed by pastoralists for centuries, harbor more species with higher spore number than the newly cultivated and prosopis-encroached areas, but sporulation and trap plant colonization is higher in soils from cultivated lands. the use of brackish water for irrigation has increased available soil p and k and this will inevitably alter physical and chemical properties of the soil, and thereby amf abundance and diversity. this effect could have a significant impact on the productivity of mechanized farms in the study area as well as in the lower awash basin. two amf species, namely, claroideoglomus claroideum and funneliformis mosse were found to be the most ubiquitous in all land use types and the most sporulating ones in sorghum trap cultures. the two amf species are recommended as potential candidates for their bio-inoculum production. furthermore, the ever-expanding prosopis encroachment on the open grassland and cultivated land around awash river necessitates implementing strict measures to decrease pressure on the soil biota underneath and enhance sustainable use of rangeland resources. 6. acknowledgments we thank haramaya university and the ethiopian ministry of science and higher education for funding the research. we also thank haramaya university, adama science and technology university, and addis ababa university for allowing us to use their greenhouse and laboratory facilities. we are very much indebted to dr. tesfaye araya for fetching laboratory chemicals from abroad for the research. 7. references almaz kebede. 2009. sustaining the allideghi grassland of ethiopia: influence of pastoralism and vegetation change. phd 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(eds.). soil sampling and methods of analysis. canadian soil science society. lewis publishers, boca raton, florida. dawit et al. east african journal of sciences volume 15 (1) 25-40 40 ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(1): 31–46 licensed under a creative commons *corresponding author: derejeduresa@gmail.com attribution-noncommercial 4.0 international license. contribution of dairy products to farm household nutrition in addis ababa and hawassadilla milk sheds in ethiopia dereje duressa1*, sintayehu yigrem2, yetenayet b. tola3, and taye tolemariam4 1*department of postharvest management, jimma university, ethiopia 2school of animal and range sciences, hawassa university, ethiopia 3department of postharvest management, jimma university, ethiopia 4department of animal science, jimma university, ethiopia abstract background: consumption of traditional dairy products is a common practice in ethiopia. however, there are limited evidences that show factors that may attribute to differences to the contribution of dairy products to family nutrition. a desegregation of factors by intra-household factors, farming systems, and milk sheds are necessary. objective: this study was aimed at assessing the contribution of dairy products to household nutrition, and also compared the two major milk sheds in ethiopia, namely, the addis ababa and hawassa-dilla. materials and methods: a cross sectional household survey was conducted in two purposively selected districts from each of the two milk sheds (wachale and angolela tera districts from addis ababa) and arsi negelle and dalle districts from hawassa-dilla). four kebeles (the smallest administrative units) from each district were selected, followed by a random selection of 320 farm households owning dairy cows. the survey was conducted using semi-structured questionnaires. results: the study revealed that the two milk sheds were significantly (p < 0.001) different in the amounts of milk produced at the household level. in hawassa-dilla milk shed the proportions of milk used for family consumption and home processing were 29.50% and 42.70%, respectively. however, in the addis ababa milk shed, 66.54% of the milk produced was sold out as raw milk. households at wachale (15%), angolela (18.8%), and dale (10.3%) districts ranked dairy products, crop-based foods, and a combination of both as the essential food groups to the family food, respectively. about 21.6% and 11.9% of the households in addis ababa and hawassa-dilla milk sheds, respectively, had year-round access to milk and dairy products for household consumption. milk is most commonly given to children under five-years of age in both milk sheds. other foods sourced from animals such as beef, fish, chevon, poultry were consumed rarely and appeared only on certain occasions and holidays. conclusion: this study has demonstrated that dairy products are the most commonly consumed animal source foods (asfs) by the farm households in both milk sheds, which is an integral part of the food groups. keeping the intra-household and district level differences, it was observed that the addis ababa milk shed is more accessible to raw milk markets; hence the proportion of milk sold out as raw milk is higher, and the proportion of milk that is traditionally processed into other dairy products is much less than that from farmers in the hawassa-dilla milk shed. the information generated in this study will help stakeholders to design a program that can best balance between market access/family income and family nutrition in the two milk sheds. keywords: animal sourced food; dairy product; milk consumption; ethiopian traditional dairy products mailto:derejeduresa@gmail.com dereje et al. east african journal of sciences volume 16(1): 31–46 32 1. introduction the livestock sector makes up 40% of ethiopia's agricultural gross domestic product and 27% of its national gdp (shapiro et al., 2017). under the ethiopian condition, dairy production is an integral component of animal production in various farming systems providing food and nutrition security, income generation, organic fertilizer, and draught power source (kebebe ergano, 2019). the total cattle population of ethiopia is estimated at 65.35 million heads, of which female cattle constitute 55.90% (csa, 2020). according to the same source, the total milk production was estimated at 4.2 billion liters. this amount of milk is too low for the current human population of ethiopia, and hence the per capita milk consumption is much lesser than the world and subsahara countries average figures of 84 liters and 36 liters, respectively. even if the total cattle population of ethiopia has been rising over the years, the per capita cattle holding has been reducing substantially. according to the 2020 estimate majority (4,817,176 households) keep 1 to 2 heads of cattle and 4,499,849 households keep 3 to 4 heads of cattle. milk is considered a nutrient-dense food, providing essential nutrients to humans. important nutritional contents of milk and milk products include fat, protein, lactose, calcium, potassium, phosphorus, vitamin a, vitamin b12, riboflavin, niacin (or niacin equivalents), and vitamin d (miller et al., 2007). in response to an increasing population, urbanization, rising income, and emerging middle-class society, the demand for livestock products is rising in ethiopia (francesconi and heerink, 2011). the report of the ethiopian academy of sciences indicates that shortage of animal-sourced foods, particularly milk has a negative consequence in the process of child growth and ultimately building a productive workforce that plays pivotal roles in the country's economic development (eas, 2013). in ethiopia, there is strong evidence on the link between the consumption of asf (animal source foods), notably milk, and improved nutritional outcomes among children (hoddinott et al., 2015; sadler and catley, 2009). in many developing countries in which staple foods dominate the composition of diets, a higher consumption of animalsourced foods is associated with noticeable nutritional benefits (fantu bachewe et al., 2017). most of the milk produced by ethiopian farmers is consumed at the household level in fresh or fermented forms. popular ethiopian fermented dairy products made using traditional methods include spontaneously fermented milk curd, butter, ghee, and cottage cheese), hazo (spiced fermented buttermilk), arera (defatted sour milk), and whey water (tesfamariam berhe et al., 2017). small-scale livestock holders supply the vast majority of milk and dairy animals that provide household food security which are a means of fast returns for them (fao, 2013). milk and fermented dairy products have a long history of use, as far back as the seventh millennium bc (evershed et al., 2008). the long-standing culture of dairy product consumption in ethiopia indicates the importance and potential of dairying in the country (azage tegegne et al., 2013). however, variations may occur among the milk sheds due to the socio-cultural setups of the society and agro-ecological conditions, which affect the farming systems. as a nutrition, livestock products in general and dairy products in particular support the livelihood of a family by complementing other farm products. nevertheless, the contributions of dairy products as compared to other animal source foods (asfs) and crop-based foods (cbfs) were not well explored especially at household level. in the absence of such information, smallholder producers might not give sufficient emphasis to their dairy animals and dairy products. according to wytze et al. (2013), about 98% of milk comes from smallholder farmers that constitute about 85% of the country's population. of all livestock products, the share of dairy products is the highest. overall, 70% (national level) of the milk consumed in ethiopia is sourced from own farms, but there exists a great difference between rural and urban dwellers. only 14.5% of urban dwellers source milk from their farms, while 80% of dwellers in rural settings produce and consume milk from their farms. therefore, milk plays a great role in family nutrition, notably to children. a study by sintayehu yigrem et al. (2015) has shown the associations between milk production/consumption and the nutritional status of children in farm households. the nutritional contribution of animal-sourced foods, in general, is indisputable. however, there is limited evidence that shows factors that may attribute to differences in the contribution of dairy products to family nutrition. desegregation of factors by intra-household factors, and by farming systems and milk sheds are necessary. if the disaggregation is done, useful information could be generated to design specific development and nutrition intervention programs across the milk sheds. in addition, exploring such evidences at household level will help the producers and consumers dereje et al. contribution of dairy products to household nutrition 33 had better understand the nutritional outcomes of dairy products. the present study was designed to answer the research question “how do milk and dairy products contribute to family nutrition of farm households in the two milk sheds”? therefore, this study was aimed at assessing and analyzing contributions of dairy products to household nutrition and compared the addis ababa and hawassa-dilla milk sheds. 2. materials and methods 2.1. description of the study area the study was conducted between december 2018 to february 2019, in four districts selected from two major milk sheds in ethiopia. angolela tera and wachale districts are from the addis ababa milk shed whereas arsi negelle and dale districts are from the hawassa-dilla milk shed. the districts were selected purposively due to their potential for dairy production. the assessment report of wytze et al. (2013) indicated that addis ababa (north shewa) and hawassa-dilla milk sheds were ranked first and third, respectively, for the milk value chain and sector development objectives of the country. this was the reason why the two milk sheds were selected for this study. angolela tera district is located in the north shewa zone of amhara national regional state, situated at the distance of about 120 km from addis ababa in the northerly direction between 9° 38' 0" north latitude and 39° 26' 0" east longitude. the altitude of the district ranges between 1,700 and 3,044 meters above sea level. according to the population projection for 2017, the district has a total population of 95,476 of which 47,516 were females and 47,960 males; and 89,638 were rural inhabitants (csa, 2013). there are 19 rural and one urban kebeles in the district. wachale district is one of the districts in the north shewa zone of oromia national regional state. it is located between 9° 24' 59.99" north latitude and 38° 49' 59.99" east longitude at the distance of about 78 km from addis ababa in the northerly direction on the main road to fiche, the capital of the zone. the altitude of the district ranges from 1200 to 2880 meters above sea level. the census report projected for 2017 (csa, 2013) showed that wachale district has a total population of 124,126 of whom 61,902 were men and 62,224 were women; and 116,268 of its population are rural inhabitants. the district has 24 rural and one urban kebeles. both angolela and wachale districts are characterized by highland agro-climatic conditions. arsi negelle is one of the districts in the west arsi zone of oromia national regional state located at the distance of about 25 km from shashamane, the capital of the zone in the central rift valley region of the country. the district is located between 7.15°n to 7.75°n latitudes and 38.35°e to 38.95° e longitudes at an altitude range between 1500 to 3000 meters above sea level. according to the projected census report for 2017, the arsi negelle district has an estimated total population of 337,918 of which 166,162 are male, and 171,756 are females (csa, 2013). maize and wheat are the dominant crops grown in the district. both rural and urban residents, playing a vital role in the people’s livelihood, rear all livestock classes, including poultry. the district has 43 rural and three urban kebeles. dale is one of the districts found in the sidama regional state, which is located at the distance of about 40 km from hawassa towards southerly direction. the district is located between 6° 50' 30" to 6° 39' 30"north latitude and 38° 17' 0" to 38° 32' 0" east longitude at an elevation ranging from 800 to 2600 meters above sea level. according to the national census report projected for 2017, dalle district has a total population of 317,246 (male = 50.31% and female = 49.69%) of which 252,739 (79.67%) dwells in the rural parts of the district (csa, 2013). dereje et al. east african journal of sciences volume 16(1): 31–46 34 figure 1. map of the study districts in addis-ababa and hawassa-dilla milk sheds. 2.2. study design and data collection a cross-sectional survey was employed for this study. a pre-tested semi-structured questionnaire (translated into the local languages of afaan oromoo, amharic and sidamu affoo) was used. both quantitative and qualitative data were collected through a face-to-face interview. the collected data included socio-economic characteristics, the quantity of daily milk production and utilization, the importance of the major food groups, the relative abundance of dairy products and other animal source foods in family nutrition, animal source foods commonly consumed with crop-based-foods, frequency of consumption of animal source foods. moreover, interviewed households ranked the utilization of dairy products by family members. finally, the main reasons for the traditional processing of milk at the household level were listed and ranked by farmers. ranking of the importance of major food groups was based on the food type preferred in terms of its nutritional importance as compared to other food items. abundance dairy products were to be compared with other animal source foods (beef, chevon, chicken, eggs, and fish) in terms of quantity in a given family food. questionnaires were pilot-tested before the actual data collection, by welltrained enumerators. 2.3. sampling procedure and sample size a total of 16 kebeles (the lowest administrative units) were randomly selected, from where twenty households were selected from each kebele using a systematic sampling technique by applying interval sampling procedure (kothari, 2004): ith = n n where, i = sampling interval, n = sampling units (20), and n = population (households owning cows). using this equation, the total number of households owning milking cows (n) was obtained from the fresh list of each kebele and divided by 20 to get the lists by interval (i). then the first sample (individual) was randomly selected from the first (i) households and then after, every ith individual was automatically included in the sample selection of each kebele. on this basis, twenty households were selected from each of the sixteen kebeles, making 320 households for primary data collection. dereje et al. contribution of dairy products to household nutrition 35 2.4. data analysis data were analyzed using ibm spss statistics version 23 computer software (ibm corp., 2016). the results of the survey data were summarized using descriptive statistics (frequencies, means percentages). pearson chi-square test was applied to identify significant differences among the groups (milk sheds and study districts) concerning categorical variables. mean differences between the quantitative variables for the two milk sheds were tested using independent samples t-tests. data for ranked variables were analyzed and presented using the ranking index (ri) formula (musa et al., 2006). 3. results and discussion 3.1. socio-economic and demographic characteristics of households socio-economic and demographic characteristics of the households are presented in table 1. family size showed a significant (p < 0.05) difference between the two milk sheds. the overall average family size (6.31) of the two milk sheds was higher than the national average of 4.7 (csa, 2020). overall, the interviewed household heads had an average age of 44 years, which is between that of mi’eso (39.7) and shashemene (51.9) average ages in years as reported by azage tegegne et al. (2013). in addition, other continuous variables namely land holding, cattle holding, number of lactating indigenous and crossbreed cows showed highly significant (p < 0.001) differences between the two milk sheds. households in both milk sheds kept mixed herds of local and improved breeds. the average number of heads of cattle held by households in the addis ababa milk shed (7.45 ± 0.35) was significantly higher than the number of heads of cattle held by hawassa-dilla milk shed (with 4.98 ± 0.29). similarly, a highly significant (p < 0.001) numbers of lactating crossbred cows (1.84 ± 0.10) were owned by households of addis ababa milk shed. amanuel asefa (2014) reported an average holding of crossbred cows of sululta, welmera, and berek as 2.81, 2.3, and 0.94, respectively, which is lower than the current findings. the variations might be attributed to the increasing demand for dairy products which might have in turn led household to having more exotic dairy animals. the relatively higher number of crossbred cows in the addis ababa milk shed might be attributed to factors such as the suitability of the area in terms of climate and market. grade 5−8 is the maximum educational level attained by most of the households in both milk sheds. however, the study by habtamu didanna et al. (2017) showed that about 50.5% of studied households in ada’a district attained the level of secondary education. among the demographic variables, religion and educational status of households showed highly significant (p < 0.001) differences between the two milk sheds. the majority of households were male-headed with 80.63 and 78.75% for addis ababa and hawassa-dilla milk sheds, respectively. the largest majority of households in the addis ababa milk shed were members of the ethiopian orthodox tewahido church whereas the majority of households in the hawassa-dilla milk shed are members of the protestant (evangelical) churches or followers of islam. this difference in religion has implications for the consumption of animal-sourced foods. the ethiopian orthodox tewahido church has over 200 days of fasting days in a year, notably fasting animal-sourced foods including milk. dereje et al. east african journal of sciences volume 16 (1) 31-46 36 table 1. socio-economic and demographic characteristics of households in addis ababa (a.a.) and hawassa-dilla (h-d) milk sheds. characteristic a.a. milk shed (n = 160) h-d milk shed (n = 160) t-test overall (n = 320) mean ( se) mean ( se) p-value mean ( se) household head’s age (years) 44.20 ± .83 44.89 ± 1.03 0.599ns 44.55 ± 0.66 family size (heads) 6.04 ± 0.18 6.59 ± 0.19 0.041* 6.31 ± 0.13 landholding (hectare) 2.69 ± 0.17 1.22 ± 0.08 0.001*** 1.95 ± 0.10 cattle holding (heads) 7.45 ± 0.35 4.98 ± 0.29 0.001*** 6.21 ± 0.24 lactating indigenous cows (heads) 0.43 ± 0.05 0.92 ± 0.07 0.001*** 0.67 ± 0.04 lactating cross breed cows (heads) 1.84 ± 0.10 0.77 ± 0.11 0.001*** 1.30 ± 0.08 lactating pure exotic cows (heads) 0.19 ± 0.05 0.13 ± 0.03 0.255ns 0.16 ± 0.03 experience in cattle keeping (years) 17.68 ± 0.82 18.23 ± 0.93 0.657ns 17.96 ± 0.62 distance from the nearest market (km) 4.79  0.52 3.57 ± 0.24 0.036* 4.18 ± 0.29 socio-demography freq. and (%) freq. and (%) χ2− value gender male 129 (80.63) 126 (78.75) 0.17 ns 255 (79.7) female 31 (19.37) 34 (21.25) 65 (20.3) educational status 29.44*** none 50 (31.25) 18 (11.25) 68 (21.3) grade 1–4 34 (21.25) 27 (16.88) 61 (19.1) grade 5–8 38 (23.75) 73 (45.63) 111 (34.7) grade 9–10 19 (11.88) 28 (17.5) 47 (14.7) grade 11–12 6 (3.75) 5 (3.13) 11 (3.4) above grade 12 13 (8.13) 9 (5.63) 22 (6.9) religion 195.59*** islam 2 (1.25) 44 (27.5) 46 (14.4) orthodox christian 156 (97.5) 33 (20.63) 189 (59.1) protestant christian 2 (1.25) 78 (48.75) 80 (25.0) catholic christian 0 (0.0) 2 (1.25) 2 (0.6) wakefata 0 (0.0) 3 (1.88) 3 (0.9) note: *** and * refer to levels of significance at p < 0.001 and p < 0.05, respectively. ns = non-significant at 5% level of probability. n and n = sample sizes. se = standard error of the mean; a.a. = addis ababa and h-d = hawassa-dilla. 3.2. daily milk production and utilization as depicted in table 2, significant differences were observed between the two milk sheds (p< 0.001) in the amounts of milk produced per farm and day. the mean daily milk production was higher for addis ababa (17.87±1.17 litters) than for hawassa-dilla milk shed (8.9±0.92 litters), which could be due to the more significant number of cross and pure exotic breed cows owned by households of the former milk shed. the average value reported in this study is almost similar to a recent study reported for ada'a district, which is within the addis ababa milk shed (habtamu didanna et al. (2017). out of the total milk volume produced daily, about 29.50% and 42.70% of the milk in the hawassadilla milk shed was used for home consumption and processing, respectively. however, most of the daily milk produced by households in the addis ababa milk shed is sold out as raw milk (66.54%). as the addis ababa milk shed is located within the capital city, it has access to the largest number of milk processing plants. hence, milk collectors have been expanding the radius of their operation now reaching up to 150 km range. market proximity to raw milk has many implications for the amounts of milk left at home for either consumption or processing into other traditional dairy products. in both milk sheds, a considerable amount of milk (31.07±1.69) is still home-processed to get more shelfstable traditional dairy products like butter. butter is the most marketable dairy product for rural farmers in ethiopia. on average, 47% of the daily produced milk is used for the market to generate income for households in both milk sheds (table 2). getachew ahmed et al. (2018) reported that dairy products' expenses make up almost half of ethiopia's animal sourced food expenditures. a study conducted in fogera woreda, ethiopia, indicated that 13.8% of the total milk produced is used to generate dereje et al. contribution of dairy products to household nutrition 37 income (belete anteneh et al., 2010) which is much smaller than the findings of the present study in the two prominent milk sheds. as presented in table 2, the daily consumption of milk of the two milk sheds with 14.05% for addis ababa and 29.50% for hawassa-dilla, is higher than that reported by habtamu didanna et al. (2017) for ada’a district with 6.03% of the mean daily milk produced. the overall mean milk retained for home processing in the two milk sheds (31.1%) is less than the report of the government of ethiopia (goe, 2007) that indicated 40% of the milk to be processed into butter. the variations in the proportion of milk consumption might be attributed to the religion of the household especially with regard to fasting by followers of orthodox christianity. table 2. farm-level quantity of milk produced daily (liter) and percentage utilization. variable a.a. milk shed (n = 160) hawassa-dilla milk shed (n = 160) t-test overall (n = 320) mean±se mean±se p-value mean±se farm-level milk production (liter/day) 17.87±1.17 8.9±0.92 0.001*** 13.39±0.77 the proportion of milk for family consumption (%) 14.05±0.78 29.50±1.6 0.001*** 21.77±0.99 the proportion of milk for home processing (%) 19.42±2.03 42.73±2.38 0.001*** 31.07±1.69 the proportion of raw milk for the market (%) 66.54±2.52 27.56±2.60 0.001*** 47.05±2.11 note: *** refers to level of significance at p < 0.001. n and n = sample sizes. se = standard error of the mean. a.a. = addis ababa. 3.3. major food groups and family nutrition table 3 shows common food groups that play essential roles in terms of both relative importance and abundance as family nutrition in the two studied milk sheds. compared to all animal-sourced foods, dairy products were observed as the most frequently consumed animalsourced food items. the most common dairy products in ethiopia are cow milk and products processed from the milk, which includes ergo (naturally fermented milk), butter, cottage cheese, and arera (buttermilk, defatted sour milk), and ghee (nitir kibe). other animal-sourced foods (oasfs) indicated in this study were animalsourced foods (asfs) other than dairy: beef, the meat of small ruminants, chicken, eggs, and fish. the households at wachale (15%), angolela (18.8%), and dale (10.3%) districts rated dairy products, crop-based foods, and the combination of the two as the essential food groups in their family nutrition, respectively. this is in agreement with the results of getachew ahmed et al. (2018) who reported that the most critical animal-sourced food (asf) consumed in ethiopia in terms of quantity is dairy products. the chi-square result showed significant (p < 0.001) differences among the study districts concerning the rank of most common food groups that contributed to family nutrition. about 17.2% of households of addis ababa milk shed ranked dairy products as the most common food group. in comparison, 16.6% of households in the hawassa-dilla milk shed ranked a combination of dairy and crop as essential food groups. cow's milk contains about 3.5% protein by weight, which accounts for about 38% of the total solids-not-fat milk content and contributes about 21% of whole milk's energy. cow's milk contains about 4.8% lactose (12 to 12.5 g lactose/cup) compared with 7% (15 to 18 g lactose/cup) in human milk (miller et al., 2007). the use of dairy products in the family food reported in the present study is, therefore, an opportunity to get those constituents in human nutrition. getachew ahmed et al. (2018) reported that animal source foods' relative importance was low at 11.2% in 2011 based on ethiopia's per capita consumption expenditure. according to abdulhalik et al. (2016), the highest intake of milk (with 80.7%) and lowest (with 14%) were recorded in somali and benishangul gumuz national regional states of ethiopia, respectively. dereje et al. east african journal of sciences volume 16 (1) 31-46 38 table 3. food groups rated as most important and most abundant for family nutrition (% of households) in addis ababa and hawassa-dilla milk sheds. asfs in nutrition districts milk shed angolela (n = 80) wachale (n = 80) arsi negelle (n = 80) dale (n = 80) total (n = 320) χ2 addis ababa hawassa dilla total χ2 most important dairy products 2.2 15.0 3.1 6.3 26.6 119.7*** 17.2 9.4 26.6 37.8*** other asfs 0.3 0.6 0.0 0.0 0.9 0.9 0.0 0.9 crop based foods 18.8 7.8 15.3 6.6 48.4 26.6 21.9 48.4 dairy + other asfs 0.3 0.0 0.0 1.3 1.6 0.3 1.3 1.6 dairy + crop-based food 2.8 1.3 6.3 10.3 20.6 4.1 16.6 20.6 dairy + other asf + crop foods 0.61 0.3 0.3 0.59 1.9 0.91 0.89 1.9 most abundant dairy products 23.8 24.1 24.4 24.1 96.3 3.29ns 47.8 48.4 96.3 1.10ns other asfs 0.9 0.9 0.6 0.9 3.4 1.9 1.6 3.4 both dairy and other asfs 0.3 0.0 0.0 0.0 0.3 0.3 0.0 0.3 note: asfs = animal source foods, numbers in bold indicate the majority of households (%) who ranked respective food groups as most important. n = sample size. *** refers to level of significance at p < 0.001; and ns = non-significant at 0.05 level of probability. dereje et al. contribution of dairy products to household nutrition 39 3.4. relative abundance of animal source foods (asfs) households were asked to rank the abundance of asfs (dairy products, other animal source foods, and their combinations) and their contributions to family nutrition (table 3). the chi-square analysis showed that relative abundance of animal-sourced foods showed nonsignificant (p > 0.05) differences among districts and milk sheds. however, dairy products are relatively more abundant than other animal-sourced foods playing more contributions to the family nutrition of hawassa-dilla milk shed. in contrast, other animal-sourced foods are relatively plentiful in the meals of addis ababa milk shed's households. in terms of the quantity of asf consumed, the most important asf is dairy products, as was the case for expenditures at the national level (getachew ahmed et al., 2018). the findings of this study further indicated that dairy products are more abundant in the meals of households in both milk sheds compared to other animal-sourced foods. the reason behind this might be the preference for milk by people of all ages. besides, the possibility of processing the milk into various traditional products at home could give its relative abundance over other animalsourced foods. this is because many types of dairy products are traditionally processed from milk and used in different forms as family food. the report of befekadu teshome et al. (2019) in the borana zone of ethiopia indicated that 17.17% of the households process milk for the preservation and diversify products for consumption. consistent with the results of this study, hoddinott et al. (2013) stated that close to other micronutrient-rich foods (particularly animal-sourced foods), milk is consumed in relative abundance in many developing countries and is generally one of the largest sources of animal-based proteins. contrary to the finding of this study, however, abdulhalik et al. (2016) reported that cereals were the most commonly (96%) consumed food groups consumed in ethiopia. 3.5. animal-sourced foods commonly consumed with crop-based foods the chi-square value showed significant differences (p < 0.05) for the asfs commonly consumed with crop-based family foods (table 4) among the study districts and milk sheds. in hawassa-dilla milk shed dairy products, the meat of small ruminants and beef are the three asfs commonly consumed with crop-based foods with 38.1, 4.4, and 3.4%, respectively. on the other hand, dairy products (36.6%), eggs (5.6%), meat of small ruminants (4.1%), and chicken (3.4%) are in order of importance, commonly consumed with crop-based foods by households of addis ababa milk shed. diets without livestock-sourced foods (lsf) can be deficient in vitamin a and b12, riboflavin, calcium, iron, and zinc (murphy & allen, 2003). fao (2013) stated that milk and dairy products can add the much-needed diversity to plant-based diets and can contribute to promoting child growth. getachew ahmed et al. (2018) reported that beef and dairy products are the most important animal-sourced food groups consumed in ethiopia. they further indicated that cow milk constituted 45% of the total consumption of dairy products in 2011. the findings of the present study indicated that traditional foods comprising animalsourced foods could provide those nutrients lacking in the staple crop-based foods. moreover, the habit of the community, which is consuming dairy products with crop-based foods, may support the fact stated by fao (2013) as “dairy foods and their nutrients are not consumed in isolation and no single food can supply all essential nutrients”. table 4. animal source foods (asfs) commonly consumed with crop-based foods in districts of addis ababa and hawassa-dilla milk sheds (% of households). types of asfs districts angolela (n = 80) wachale (n = 80) arsi negelle (n = 80) dale (n = 80) total (n = 320) χ2 p-value dairy products 17.2 19.4 19.7 18.4 74.7 30.19 0.003* beef 0.3 0.0 2.2 1.3 3.8 small ruminant meat 1.9 2.2 1.3 3.1 8.4 chicken 2.5 0.9 0.3 2.2 5.9 eggs 3.1 2.5 1.6 0.0 7.2 note: * refers to level of significance at p < 0.05. dereje et al. east african journal of sciences volume 16 (1) 31-46 40 3.6. year-round availability of milk and family nutrition a significant (p < 0.001) difference was observed for the year-round availability of milk in family nutrition between the two milk sheds (table 5). in addis ababa milk shed, 21.6% of households access a certain amount of milk for the year-round nutrition of their family, whereas 10.3, 7.2, and 10.9% of the households access some milk in their food for nine, six, and less than three months per year, respectively. in the hawassa-dilla milk shed, about 12.2% of households get some milk for six months of a year while a certain amount of milk was accessed the whole year by 11.9% of the households. about 19.2% of households in the hawassa-dilla milk shed access milk for less than three months of a year. the length of time for availability of other animal sourced foods may depend on access, economic status, and knowledge or custom of the consumers. the results of this study indicate that households use milk and milk products in the diets of their family, which shows that they are aware of the nutritional value of milk as an essential food for the growth, health, and strength of family members. getachew ahmed et al. (2018) reported that almost 80% of dairy products are obtained from production in ethiopian rural areas, with a few households relying on purchases to get these products. the researchers indicated that dairy products show much less seasonal variation than meat products among which butter shows less seasonal variation across the year as it is usually used to cook other animal-sourced foods. table 5. availability of milk for family nutrition across the year (frequency and percent of households). note: a.a. = addis ababa and h-d = hawassa-dilla. *** refers to level of significance at p < 0.001. 3.7. frequency of consumption of animal-sourced foods the frequency of consumption of animal-sourced foods (dairy products and other animal source foods) is depicted in table 6. yogurt or fermented milk is the basic raw material for the production of most ethiopian dairy products. about 0.6% of the households in the addis ababa milk shed consume whole milk more than once per day while the value for hawassa-dilla milk shed is 19%. ghee is mainly consumed on special occasions and ceremonies in both milk sheds. the consumption habit may vary due to food habits, income, and availability of the asfs. for instance, some families who commonly consume enset (ensete ventricosum) based foods include butter, cheese, or meat as mandatory components of the meal thereby obtaining balanced nutrition. among the other animal-sourced foods, beef, meat of small ruminants, and chicken are frequently consumed on special ceremonial occasions such as holidays and festivities in both milk sheds. these products are also consumed with a frequency of 1−2 times/month. the frequency of consumption of oasfs per day, more than once per day, and 3−6 times per week are low compared to the consumption of dairy products in both milk sheds. yearly availability of milk in family nutrition milk shed (n = 320) χ2 p-value a.a. (n =160) h-dilla (n = 160) total (n = 320) some amount available across the year 69(21.6) 38(11.9) 107(33.4) 23.29 0.001*** some amount available for 9 months 33(10.3) 21(6.6) 54(16.9) some amount available for 6 months 23(7.2) 39(12.2) 62(19.4) some amount available for 3 months or less 35(10.9) 62(19.4) 97(30.3) dereje et al. contribution of dairy products to household nutrition 41 table 6. frequency of consumption of animal source foods (asfs) by households of addis ababa and hawassa-dilla milk sheds (n = 320). type of animal product frequency of consumption in the milk sheds (%) more than once per day ones per day 3–6 times per week 1–2 times per week 1–2 times a fortnight 1–2 times per month on special occasions not common χ2 a.a. h-d a.a. h-d a.a. h-d a.a. h-d a.a. h-d a.a. h-d a.a. h-d a.a. h-d dairy whole milk 0.6 0.0 15.3 19.1 11.6 10.0 18.8 16.6 3.4 2.5 0.0 0.3 0.3 1.6 0.0 0.0 0.221ns yogurt 0.0 0.0 4.1 6.6 11.3 19.7 21.9 10.9 6.6 5.0 5.3 1.3 0.6 5.9 0.3 0.6 0.001*** butter 0.0 0.0 4.1 4.1 10.9 15.0 15.6 11.6 6.3 7.2 10.0 7.8 1.9 4.4 1.3 0.0 0.057ns butter milk 0.0 0.0 1.6 13.8 9.4 15.9 12.8 10.6 5.0 1.3 9.7 1.9 5.0 0.6 6.6 5.9 0.001*** cheese 0.0 0.0 3.4 1.6 15.0 4.1 14.4 6.6 6.3 9.4 6.6 7.5 3.1 15.3 1.3 5.6 0.001*** ghee 0.6 0.0 8.8 3.4 8.4 7.8 8.8 13.1 3.1 4.1 7.2 5.3 12.2 12.8 0.9 3.4 0.011* whey 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.9 0.0 2.5 0.0 0.3 0.0 45.0 50.0 0.001** oasf beef 0.0 0.0 0.0 0.0 1.3 3.8 5.0 3.4 3.1 5.6 16.6 10.0 24.1 24.7 0.0 2.5 0.001** shoats 0.3 0.0 0.3 0.0 0.6 3.4 2.2 5.6 8.1 3.8 10.0 8.4 24.1 26.9 4.4 1.9 0.002* chicken 0.0 0.0 0.6 0.9 2.5 7.5 4.7 4.4 3.4 1.9 5.0 7.2 23.4 23.8 10.3 4.4 0.005** eggs 0.6 0.0 0.9 1.6 10.6 13.1 14.4 9.7 6.9 5.3 1.9 16.6 6.9 1.3 7.8 2.5 0.001*** fish 0.0 0.3 0.0 0.0 0.0 0.9 0.6 1.3 0.3 0.9 0.6 3.1 4.4 2.8 44.0 41.0 0.051ns note: oasf = other animal sources foods. a.a. = addis ababa and h-d = hawassa-dilla. *, ** and *** refer to significance level at p < 0.05, p < 0.01 and p < 0.001, respectively; and ns = non-significant at 0.05 probability level. dereje et al. east african journal of sciences volume 16 (1) 31-46 42 as shown in table 6, once per day consumption of dairy products is more common for hawassa-dilla milk shed households than for addis ababa milk shed households. the findings of the present study indicated that households of both milk-sheds more frequently consume dairy products compared to other animal-sourced foods. among the dairy products, whey and buttermilk are the less commonly consumed ones in both milk sheds. similarly, fish consumption is less common in the two milk sheds due to shortage of the food in the localities. kassahun melesse and fekadu beyene (2009) reported that whole milk was the most frequently consumed dairy product in the ada'a district, where almost 100% of the high and 66.7% of the medium income group households in urban areas drink raw milk more than 3 to 6 times per week. the same authors further reported that 33.3%, 33.6%, and 6.7% of urban low, peri-urban low, and rural high-income households consumed raw milk only on special occasions and holidays. amanuel asefa (2014), on the other hand, reported that following milk, the most widely used dairy product in addis ababa is spiced ghee and soft cheese mainly during holidays. the frequency of consuming whole milk daily is higher in addis ababa milk shed households, which might be attributed to a relatively more number of the cross and pure breed milk cows associated with milk supply and availability. the report of habtamu didanna et al. (2017) for ada'a district indicated that the majority (66.5%) consumed milk, of which 63.1% drank it once a day, 25.4% more than once a day, 6.2% three to six times per week, and 5.4% once or twice per week. 3.8. intra-household variations in utilization of dairy products as depicted in table 7, utilization of various traditional dairy products by family members of different age groups showed highly significant (p < 0.001) differences between the two milk sheds. whole milk is commonly saved and given to children under five years of age in both milk sheds. other age groups usually utilize other products like yogurt, butter, buttermilk, cottage cheese, and ghee. in addis ababa milk shed, butter, cheese, and ghee are dairy products mainly consumed by family members of all age groups, compared to hawassa-dilla, where these products are more commonly consumed by household heads. the utilization of all products by household heads is optimum except for whole milk, which is mainly meant for children. it is seen from the table that family members of all age groups utilize all dairy products, though the degree of utilization varies. whey is the least utilized product, and if any, by youths in both milk sheds, which might be related to cultural issues. this is in agreement with the report of tesfamariam berhe et al. (2017) that stated aguat is thus usually given to animals (calves, cows, and dogs) and sometimes consumed by humans but not in agreement with teshome gemechu and tesfaye amene (2017) who reported about 6.7 and 16.7% of households in debub and shey bench districts, respectively use whey for consumption. the study conducted in ada’a district by habtamu didanna et al. (2017) indicated that 85% of children in households consume milk. the report of the ethiopian national food consumption survey (2013) also indicated that consumption of dairy is highest for children. similarly, the survey results by potts et al. (2019) from four regions of ethiopia indicated that milk is the most commonly consumed asf (48%) by young children. the review report of tesfamariam berhe et al. (2017) indicated that buttermilk is mainly used to supplement the diets of children and the elderly in rural areas whereas traditional ghee (nitir kibe) is consumed in all parts of the country by all classes of people. many authors (cite the authors here) stated the importance of dairy products for family members of different age groups. grace et al. (2018) reported that livestock-derived foods (ldf) are considered as key to improved nutrition during the first 1000 days of age, from conception up to two years. these micronutrients, necessary for infants and young children, are mostly insufficient, absent, or poorly bioavailable in plant-based diets. this makes dairy products an essential source of nutrition (randolph et al., 2007). hoppe et al. (2004) also indicated that the positive association of milk consumption and improved child growth and consumption of fermented milk resulting in the prevention of diarrhea, consumption of even small quantities of milk, can markedly improve the nutritional quality and diversity of the diet. cow milk is a source of vitamin b12, a micronutrient commonly deficient in populations that consume low amounts of asf, and can thus help to improve children’s nutritional status (allen and dror, 2011). dereje et al. contribution of dairy products to household nutrition 43 table 7. dairy products utilization by family members of different age. dairy products family members utilization (frequency and %) χ2 addis ababa (n = 160) hawassa-dilla (n = 160) total (n = 320) whole milk children ≤ to 5 yrs 92(28.8) 78(24.4) 170(53.1) 26.50*** children 6–18 yrs 2(0.6) 19(5.9) 21(6.6) youths above 18 yrs 2(0.6) 1(0.3) 3(0.9) hh heads 6(1.9) 21(6.6) 27(8.4) all age groups 58(18.1) 41(12.8) 99(30.9) yogurt children ≤ to 5 yrs 13(4.1) 8(2.5) 21(6.6) 18.16*** children 6–18 yrs 38(11.9) 40(12.5) 78(24.4) youths above 18 yrs 49(15.3) 26(8.1) 75(23.4) hh heads 26(8.1) 54(16.9) 80(25.0) all age groups 34(10.6) 32(10.0) 66(20.6) butter children ≤ to 5 yrs 2(0.6) 5(1.6) 7(2.2) 53.45*** children 6–18 yrs 22(6.9) 8(2.5) 30(9.4) youths above 18 yrs 23(7.2) 32(10.0) 55(17.2) hh heads 17(5.3) 66(20.6) 83(25.9) all age groups 96(30.0) 49(15.3) 145(45.3) buttermilk children ≤ to 5 yrs 6(1.9) 8(2.5) 14(4.4) 28.29*** children 6–18 yrs 20(6.3) 21(6.6) 41(12.8) youths above 18 yrs 57(17.8) 43(13.4) 100(31.3) hh heads 27(8.4) 54(16.9) 81(25.3) all age groups 33(10.3) 34(10.6) 67(20.9) not common 17(5.3) 0(0) 17(5.3) cottage cheese children ≤ to 5 yrs 3(0.9) 1(0.3) 4(1.3) 58.69*** children 6–18 yrs 23(7.2) 5(1.6) 28(8.8) youths above 18 yrs 28(8.8) 32(10.0) 60(18.8) hh heads 18(5.6) 74(23.1) 92(28.8) all age groups 88(27.5) 48(15.0) 136(42.5) ghee children ≤ to 5 yrs 8(2.5) 4(1.3) 12(3.8) 73.37*** children 6–18 yrs 6(1.9) 1(0.3) 7(2.2) youths above 18 yrs 19(5.9) 39(12.2) 58(18.1) hh heads 19(5.9) 74(23.1) 93(29.1) all age groups 108(33.8) 42(13.1) 150(46.9) note: *** refers to level of significance at p < 0.001. numbers in parentheses are percentages of households. 3.9. reasons for processing the milk into traditional products the processing of milk into various forms of dairy products is dominated by traditional practices in ethiopia. the objective of processing may vary with the sociocultural setting of the society and the availability of milk. according to tesfamariam berhe et al. (2017), the processing of fresh milk into dairy products results in value-added products and improves the shelf life and functional properties of the product. on average 31.07% of the daily milk produced in the studied milk sheds was retained for traditional processing. the reasons for home processing of milk into various traditional products in both milk sheds were ranked using a ranking index (musa et al., 2006) and presented in figure 2. in the addis ababa milk shed, the primary reason for home processing of milk was for enhancing the shelf-life dairy products (index = 0.23) and value addition from available market opportunities and prices, ease of transportation of products, and make use of surplus milk to minimize the food loss. on the other hand, obtaining diversifying dairy-based products for better nutrition (index = 0.27) was ranked as the primary reason for processing milk by hawassa-dilla milk shed households. this fact indicates how dairy products are important in diversifying the diets of households in hawassa-dilla milk sheds. though the primary reasons are different, the index indicates that households of both milk sheds reflect dereje et al. east african journal of sciences volume 16 (1) 31-46 44 similar reasons for processing milk at home. ease of transporting and surplus milk was ranked the least reasons for milk processing in both milk sheds. sadler and catley (2009) estimated that 40% of the milk produced is converted to butter in rural ethiopia, while only nine percent is converted to cheese. shapiro et al. (2017) stated two reasons for processing the milk into butter in ethiopia, which are the rising of butter price over time and the increased shelf life of the products, particularly in rural areas. figure 2. index for the reason for processing milk at home by households of addis ababa (a.a.) and hawassa-dilla (hd) milk sheds. 4. conclusions and implications this study has revealed that households in the addis ababa milk shed hold more cross and pure-bred milk cows. as a result, the mean daily milk production (liters) is much higher than that of the hawassa-dilla milk shed. the results of the study indicated that dairy products are the most commonly consumed animal-sourced foods (asfs) by the farm households in both milk sheds, which is an integral part of food groups. keeping the intrahousehold and district level differences, it was observed that the addis ababa milk shed is more accessible to raw milk markets; hence the proportion of milk sold out as raw milk is higher, and the proportion of milk that is traditionally processed into other dairy products is much less than that from farmers in the hawassa-dilla milk shed. the information generated in this study will help stakeholders to design a program that can best balance between market access/family income and family nutrition in the two milk sheds. detailed studies across the milk value chain are required to explore evidences that could substantiate the present study. 5. acknowledgments this research was funded by the feed the future initiative of usaid through livestock systems innovation lab (lsil), a collaborative project between hawassa university (hu) and kansas state university (ksu) and its partners texas tech university. we are also grateful to all households who participated in this survey study. 6. references abdulhalik workicho, tefera belachew, garumma tolu, beyene wondafrash, carl, l., et al. 2016. household dietary diversity and animal source food consumption in ethiopia: evidence from the 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nigussie, k., et al. 2017. ethiopia livestock sector analysis. ilri project report. ilri, nairobi, kenya. tesfamariam berhe, finn, k., richard, i., eyassu seifu, mohammed yusuf and egon, b.h. 2017. traditional fermented dairy products of ethiopia: a review. east african journal of sciences, 11(2): 73– 80. teshome gemechu and tesfaye amene. 2017. dairy cattle milk production, handling, processing, utilization, and marketing system in bench maji zone, southwest ethiopia. international journal of livestock production, 8(9): 158−167. wytze, b., dawit mengistu, binyam kassa, mahlet yohannes and jan, l. 2013. the major ethiopian milk sheds. an assessment of development potential. livestock research report, 735, wageningen ur livestock research. doi:10.13140/rg.2.1.1354.2246. http://www.lrrd.org/lrrd21/4/mele21056.htm http://dx.doi.org/10.13140/rg.2.1.1354.2246 ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15 (1) 1-16 licensed under a creative commons *corresponding author: wmanamno@gmail.com. attribution-noncommercial 4.0 international license. genetic variability and correlation of traits among progenies of potato crosses in ethiopia manamno workayehu 1*, wassu mohammed 2, and tesfaye abebe 3 1adet agricultural research center, p.o. box 8, bahir dar, ethiopia 2school of plant sciences, haramaya university, p.o. box 138, dire dawa, ethiopia 3holetta agriculture research center, holetta, ethiopia abstract background: investigating the causes and magnitude of genetic variation in segregating potato population that derived from crossing is vital to know the genetic consequences of hybridization and improve potato varieties. however, very little effort has been carried in creating local population through crossing and genetic information on created potato population. objective: the study was conducted to assess genetic variability and correlation among traits in locally created potato crosses population. materials and methods: a total of 81 genotypes were evaluated for 18 traits in a 9 x 9 simple lattice design. data collection and analysis was done from sixteen plants or central rows. results: the results revealed highly significant variations for all traits except proportion of medium tuber size and specific gravity of tubers indicating the existence of genetic variability among population. marketable and total tuber yields variability of tested genotypes ranged from 2.51 to 55.62 t ha -1 and 10.82 to 58.31 t ha -1, respectively. the phenotypic and genotypic coefficients of variation ranged between 4.67 to 92.88% and 3.25 to 73.5%, respectively. heritability in broad sense and genetic advance as percent of mean also ranged from 28.81 to 91.64% and 4.65 to 90.33%, respectively with less influence of environmental fluctuations. total tuber yield had positive and significant phenotypic and genotypic correlations with stem height, tuber yield per plant, tuber number per plant, average tuber weight and marketable tuber yield. this indicated that the traits are heritable with governing of additive gens for effective selection. conclusion: the range and mean values of the variables obtained suggest the existence of sufficient variability among the tested and possibility of wide genetic base creation for improving potato population using locally created genotypes. hence, promising genotypes with desirable traits could be recommended to produce new variety or use as parental lines for future breeding program. keywords: broad sense heritability; correlations; genetic advance; genotypes; tuber yield 1. introduction potato (solanum tuberosum l.) is a highly heterozygous tetraploid plant, originating in south america. it is a tuber bearing crop belonging to the family solanaceous and has 48 chromosomes. potato is the world’s third most important food crop in overall production after rice and wheat, and is a food security crop in ethiopia (devaux et al. 2014). it is mainly used as vegetable and available in the market throughout the year with reasonable price and has great importance in rural economy of the country as compared to other vegetables crops in ethiopia. in ethiopia, potatoes are mostly cultivated in the central, north western, southern, and eastern parts of the country (semagn asredie et al., 2016). the crop has potential for improving the livelihoods of millions of smallholder farmers in the high lands area of the country. the potential for higher yield per unit area, early maturity, and excellent food value give the potato crop greater potential for improving food security, increasing household income, and reducing poverty than other crops (semahagn asredie et al., 2015). in 2018/19, the area under potato production of maher season in the country was about 73,677.64 hectares with an average tuber yield of 14.18 t ha-1 (csa, 2019). this is relatively low, especially when considering the favorable climate at higher elevations, soils, and irrigation potential in ethiopia. the main production constraints are related to narrow genetic basis and susceptibility to diseases among varieties. ethiopia’s tremendous variation in altitude, temperature, rain fall, soil type and ecological settings also give rise to the need for a wide range of varieties, which are not likely to be provided by existing breeding programs (semahagn asredie et al., 2015). so, continuously developing new cultivars through crossing is needed for a sustainable increase in potato variability and production under the present environmental change and high human population growth (bradshaw, 2006). ethiopia has more than 36 potato varieties that are approved for cultivation to address the production problems in the country (moa, 2016). these improved varieties were developed from introduced germplasms mainly from international potato center https://link.springer.com/article/10.1007/s12230-016-9543-3#cr7 manamno et al. east african journal of sciences volume 15 (1) 1-16 2 (cip) either in the form of true potato seeds or clones and varieties imported to the country through technology shopping programs for adaptation trials and subsequent registration as a variety (gebremedhin woldegiorgis et al., 2013). creating genetic variability in tetraploid potato crop through hybridization in the country is limited due to too much dependence on cip materials (getachew assefa et al., 2016). because of this constraint most smallholder farmers are still growing old varieties that are low yielding and disease susceptible. improving productivity of the crop through hybridization is necessary to develop varieties which are adaptable to a wide range of environments (semahagn asredie et al., 2015). ethiopian local potato varieties are more heterozygous than the cip genotypes that are cultivated in ethiopia (semahagn asredie et al., 2016). varieties developed from crossing of existing local varieties are more likely to be adapted to local growing conditions. therefore, creating genetic diversity by conventional breeding using locally adapted genotypes (existing local land races and released varieties) in the country is required to reduce dependency on foreign materials and develop climate smart potato varieties which are widely adaptable and fulfill growers’ preferential traits. studying the causes and magnitude of variation from segregating population or genotypes derived from conventional crossing is vital in understanding the genetic consequences of hybridization to develop better potato varieties (mehboob et al., 2016). evaluating crossing products in different generations of selection can also help to estimate genetic parameters such as heritability to identify the best breeding strategy (antonio et al., 2012). genetic variability in potato genotypes that were introduced from cip has been studied and variability in segregation was reported by many researchers like addisu fekadu et al. (2013); abraham lamboro (2014); getachew assefa et al. (2016); wassu mohammed (2015) and tesfaye abebe et al. (2012). but not much effort has been made in a country to study the genetic variability and improve varieties by generating genotypes through crossing. hence, the present investigation was conducted to evaluate the extent of variability, heritability, genetic advance, and correlation of traits in populations of cross jalene x aterababa, belete x aterababa and gera x shenkola varieties for different yield and its related traits. 2. material and methods 2.1. description of the study site the experiment was conducted at adet agricultural research station during the main growing season in 2018. adet agricultural research center is located at the longitude ranging from 37° 28’ 38’’ to 37° 29’ 50’’ e and latitude ranging from 11° 16’ 19’’ to 11° 17’ 28’’ n in northwestern highlands of ethiopia with an average altitude of 2240 meters above sea level (andualem wolie et al., 2013). the mean annual total rainfall during the growing season was 1432 mm with the average minimum and maximum temperatures of 10.81 and 25.55 ℃, respectively. 2.2. description of the experimental materials and design the experimental materials comprised 81 genotypes. from this, seventy-five genotypes were offspring produced from biparental crossing of ethiopian potato varieties by adet agricultural research center in 2015. in addition, five high yielding parent varieties, namely, belete, aterababa, gera, shenkola and jalene and dagim (the latest registered variety) was included as a standard check for comparison in this experiment (table 2). the experiment was laid out as a 9 x 9 simple lattice design. each genotype was planted in a gross and net plot size of 1.5 m x 3m which contained two rows in plot and twenty plants per plot. medium-sized and well sprouted potato tubers were planted at the spacing of 75 cm between rows and 30 cm between plants. the recommended dose of fertilizer was applied at a rate of 81/69 n/p 2 o 5 per hectare. the whole phosphors fertilizer was applied during planting, but n source applied in split at planting, 2 weeks after emergence and at flowering at equal 1 3 rate. earthing up was executed two times throughout the entire growing period, one at 30 days and another one at 60 days after planting. fungicide chemical (ridomil) was applied once when symptom occurred on experiment to control potato late blight disease. manamno et al. genetic variability among potato progenies 3 table 1. description of parental varieties for different traits. s/n parent released characteristics 1 belete cip-393371.58 2009 strong stems, high yield and dry matter, excellent stew quality, late blight tolerance, early bulking, early maturing and good for french fries, large tuber, white flower, and tuber skin color, very susceptible for bacterial wilt, hollow heart, sometimes its shape become amorphous, bitter taste than others 2 jalene cip-37792.5 2002 good dry matter and boiling quality, early maturing, early flowering, white tuber skin and flower color, late blight susceptible shallow eye depth, good taste 3 gera kp-90134.2 2003 long storage life, strong stems, high yield, late blight tolerant and well adapted to dry areas, very high deep tuber eye, white flower and tuber skin, round tuber shape 4 shenkola kp-90134.5 2005 good taste and boiling quality, white flower and tuber skin color, good yield, oval tuber shape, shallow eye depth, good taste, has tall stem 5 aterababa local good canopy cover, stew quality, taste, early maturing, round shape, high dry matter, good market demand and storage quality, late blight susceptible, bacterial wilt resistant than others, pink tuber skin and flower color, round tuber shape note: descriptions are organized from tesfaye abebe et al. (2013) and semahagn asredie et al. (2015). table 2. list of potato offspring and parents with standard check variety used in the experiment. trt genotype trt genotype trt genotype trt genotype 1 j x a.277 22 j x a.42 43 j x a.27 64 b x a.248 2 b x a.153 23 b x a.15 44 ge xsh.186 65 j x a.18 3 j xa.296 24 j x a.49 45 j x a.130 66 j x a.123 4 b x a.174 25 b x a.60 46 b x a.163 67 b x a.207 5 j x a.94 26 j x a.77 47 j x a.67 68 j x a.186 6 b x a.225 27 gera 48 shenkola 69 b x a.129 7 ge x sh.65 28 j x a.31 49 ge x sh.206 70 j x a.122 8 belete 29 ge x sh.101 50 j x a.146 71 j x a.243 9 j x a.140 30 j x a.333 51 b x a.8 72 ge x sh.90 10 b x a.74 31 b x a.228 52 j x a.102 73 ge x sh.317 11 j x a.170 32 j xa.266 53 b x a.213 74 j x a.196 12 b x a.112 33 j x a.143 54 j x a.245 75 j x a.250 13 j x a.21 34 j x a.326 55 j x a.345 76 j x a.119 14 b x a.184 35 dagim 56 b x a.201 77 j x a.246 15 b x a.164 36 j x a.188 57 ater ababa 78 j x a.165 16 j x a.120 37 j xa.60 58 j x a.135 79 jalene 17 j x a.187 38 b x j.16 59 b x a.603 80 b x a.97 18 b x a.44 39 j x a.34 60 j x a.201 81 ge x sh.96 19 j x a.39 40 ge x sh.319 61 b x a.55 20 b x a.198 41 b x a.140 62 j x a.9 21 ge x sh.29 42 j x a.23 63 ge x sh.100 note: trt = treatment, j x a = jalene cross ater abab, b x a = belete cross ater ababa, ge x sh = gera cross shenkola, dagim = standard check variety and numbers followed crosses indicated the code of genotype (experimental material). 2.3. data collection and analysis 2.3.1. data collection observations were recorded on different traits such as days to emergency (de), days to flowering (df), days to maturity (dma), main stem number (sn), plant height (ph), tuber number per plant (tnp), tuber yield per plant (typ), very small tuber numbers (vsn), medium sized tubers (mdn), large sized tubers (ltn), tuber dry matter content (dm), tuber starch content (sc), tuber specific gravity, average tuber weight (aw), marketable tuber number (mtn), marketable yield (my), unmarketable tuber yield (unmy) and total tuber yield (ty). some of morphological qualitative traits like, flower color, plant growth habit type, predominant tuber skin color and flesh color, tuber skin type, eye depth and number per tuber were recorded in all the entries as per the standards and codes specified in potato descriptors of aicrp on potato, huaman et al. (1977) during the peak of crop growth. manamno et al. east african journal of sciences volume 15 (1) 1-16 4 2.3.2. data analysis the quantitative data were subjected to analysis of variance (anova), but descriptive statistics was used to describe qualitative data by taking samples from five plants for each trait. means for significant treatments were compared using fisher ‘s protected least significant differences (lsd) at 5% (p<0.05) level of significance. the traits that exhibited significant mean squares in anova were further subjected to genetic analyses. the phenotypic (σ2p), genotypic (σ2g) variances, environmental variance (σ2e) and the corresponding phenotypic (pcv) and genotypic (gcv) coefficients of variation for each trait were estimated following the method described by burton and devane (1953). genotypic variance (σ2g) = 𝐺𝑀𝑆−𝑀𝑆𝐸 𝑟 , phenotypic variance (σ2p) = σ2g + σ2e. where, mse =mean square of error and gms=genotypic mean square. broad sense heritability estimates and genetic advance were also calculated using the formula of burton (1952) and johnson et al. (1955), respectively: h2b (broad sense heritability) (%) = σ²g σ²p x100, where σ2g= genotypic variance and σ2p=phenotypic variance. genetic advance (ga) for each trait was computed using the formula adopted by johnson et al. (1955) as: ga= ga=k.σp.h2b.where, k= selection differential (k=2.06 at 5% selection intensity), σp= phenotypic standard deviation of the trait, h2b= broad sense heritability of the character. 3. results and discussion 3.1. analysis of variance and mean performance of genotypes results of the analysis of variance (anova) of 18 quantitative traits for the 81 genotypes showed significant (p ≤ 0.01) differences among the tested potato populations for all traits except proportion of medium tuber size (%) and specific gravity (g/cm 3) of tubers (table 3). the presence of significant differences among the genotypes obtained from three biparental crosses and their parents suggested the chance of obtaining better performing offsprings/genotypes than their parents for the different important yield and its related traits. the genotypes are expected to be highly heterozygous in which additive and non-additive gene actions and in most case, both operate (ross, 1986), (arndt and peloquin, 1990). therefore, the observed variations among the potato genotypes could be exploited through vegetative propagation. the present findings agree with findings of hajam et al. (2018) who reported significant variations among 38 genotypes for days to flowering, plant height, tuber number per plant, tuber yield per plant and average tuber weight. hirut betaw et al. (2017) reported highly significant differences among 60 progenies of 32 families, 12 twelve parents and check varieties for growth, physiological and tuber yield related traits. melito et al. (2017) also reported highly significant difference for total tuber yield from genotypes obtained biparental crosses. zakerhamid (2014) showed significant differences among 166 hybrids and two parents for plant height, main stem number per plant, tuber weight per plant, average tuber weight and tuber yield. nickmanesh and hassanpanah (2014) evaluated 127 hybrids with their two parents and reported significant differences for days to flowering, plant height, tuber weight per plant, and total tuber yield. the genotypes/offsprings, parents and the check variety observed 16 to 24, 42 to 60 and 88 to 102 days of 50% emergence, 50% flowering and 90% maturity, respectively (table 4). the 41 potato offsprings of jalene x ater ababa had lowest mean days to 50% emergency. the 24 potato progenies of belete x ater ababa also showed lowest mean days to 50% flowering. while the 10 potato offsprings of gera x shenkola manifested lowest mean days to maturity. however, the individual genotypes, j x a.277, j x a.296, j x a.187, j x a.135, j x a.201, j x a.122, j x a.196, j x a.246 and j x a.165 showed early emergency of plants than their parents, standard check variety and other genotypes. similarly, j x a.23 and j xa.130 genotypes observed early maturity (88 days) than other progenies, parents, and check variety. a total of nine potato progenies showed early maturity than the standard check variety in this study. the main stem number and stem height ranged between 2 and 9; and 32.27 and 73.33 cm, respectively (table 4). potato offspring of jalene and ater ababa exhibited the highest mean of main stem numbers whereas the maximum mean stem height recorded for progenies of gera and shenkola. genotype b x a.164 showed maximum stem height (73.33 cm) followed by ge x sh.319 (71.64 cm) but more stem numbers recorded for genotype j x a.9. these genotypes which had more main stems and tall stem height can produce high tuber yield. other authors also found the performance of crosses and parental varieties for phenological and growth traits. hajianfar et al. (2017) recorded main stem numbers ranging between 3.33 and 4.29 and stem height ranging between 52.33 and 64.77cm for potato hybrids. parmar et al. (2015) found plant height ranging from 37.16 to 54.80 cm with a mean of 42.29 cm and main stem number per hill ranging from 1.93 to 3.93 with a mean 2.91 in potato genotype. biswas (2010) showed the range of plant height from 15.0 to 57.0 cm with a mean 37.9 cm for and 1 to 6 with a mean 2.1 for main stem numbers for potato progenies. manamno et al. genetic variability among potato progenies 5 table 3. mean squares from the simple lattice anova for traits of 81 potato genotypes. trait rep df =1 blocks (adj.) df =16 genotype (unadj.) df = 80 genotype (adj.) df = 80 error (rcbd) df = 80 intra block (error) df = 64 re of sl over rcbd cv (%) de 32 3.49 8.14** 7.74** 2.5 2.25 103.61 8.36 df 9.88 4.2 77.32** 73.56** 3.54 3.37 100.92 3.97 dma 52.25 6.50 28.89** 28.76** 9.36 10.07 92.91 3.24 sn 2.47 0.82 3.12** 2.96** 0.93 0.96 96.99 25.78 sh 99.25 37.69 168.85** 150.79** 25.51 22.47 105.06 10.03 tnp 0.5 3.74 30.17** 25.12** 4.58 4.78 95.65 16.3 typ 0.0005 0.007 0.09** 0.08** 0.008 0.008 96.79 14.21 aw 30.33 53.52 587.04** 565.85** 61.58 63.59 96.83 16.7 mtn 54267 1562.95 3916.31** 3360.49** 1185.46 1091.09 102.46 25.04 my 210.12 12.72 200.13** 192.04** 16.4 17.33 94.68 16.55 unmy 286.56 3.75 20.86** 18.77** 3.83 3.86 99.42 31.3 ty 5.89 10.92 189.95** 177.46** 14.97 15.99 93.66 16.69 vsn 17515 139.8 275.23** 265.25* 142.08 142.66 99.6 32.63 mdn 19781 190.98 210.36ns 191.5ns 155.2 146.26 101.37 24.43 ltn 50.72 48.9 335.45** 327.70** 52.12 52.92 98.48 31.36 dm 37.07 3.88 20.70** 19.61** 5.4 5.78 93.43 11.05 sg 0.14 0.0009 0.001ns 0.001ns 0.002 0.002 89.13 3.53 sc 34.86 3.25 16.43** 15.52** 4.68 5.04 92.89 14.48 note: *and **significant at p< 0.05 and p<0.01 probability levels, respectively. de = days to emergency, df = days to 50% flowering, df=degree of freedom, dma = days to 90% maturity, sn = main stem number, sh (cm) = stem height, tnp = tuber number per plant, typ (g) = tuber yield per plant, aw (g) = average tuber weight, mtn = marke table tuber number, my = marketable yield t ha-1, unmy = unmarketable yield t ha-1, ty = total yield t ha-1,vsn = very small tuber size in percentage, mdn = medium tuber size percentage, ltn = large size tuber percentage, dm = tuber dry matter content(%), sg = specific gravity of tuber, sc = tuber starch content (%), cv (%) = coefficient of variation. manamno et al. east african journal of sciences volume 15 (1) 1-16 6 tested genotypes showed 6 to 25 tuber number per plant, 0.23 to 1.025kg tuber yield per plant,16.61 to 106.83g average tuber weight, 11 to 310 marketable tuber number per net plot, 2.51 to 55.62 marketable tuber yield, 0.33 to 24.9 unmarketable and 10.82 to 58.31ha-1 total tuber yield (table 4). the result of range and mean of marketable and total tuber yield were greater than the findings reported by getachew assefa et al. (2016), wassu mohammed (2014), wassu mohammed and simret burga (2015), addisu fekadu et al. (2013) and tesfaye abebe et al. (2012) from tested ethiopian cultivated varieties and nonregistered cip genotypes. the greater number of tubers per plant and marketable tuber number per plot were 25 and 246.5 for genotypes j x a.170 and j x a.18. on the other hand, the highest and significantly different tuber yield per plant, marketable tuber yield and total tuber yield noted from genotype b x a.164, followed by j x a.119. in contrast, the highest significant unmarketable tuber yield 24.9 t ha-1 was recorded for genotype ge x sh.29, followed by ge x sh.206 13.59 t ha-1 due to very deep eye depth and cracking of tubers. this may show dominance of maternal inheritance traits which gera variety (female parent) imparts very deep eye on tubers. generally, in the current study, about 40% potato offspring exhibited significantly higher total tuber yields than the standard check ethiopian variety. single genotype b x a.164 and j x a.119 showed total tuber yield advantage of 209.17% and 133.96%, respectively, over the standard check and about 36.7% and 3.5% yield advantage over belete (high yielding registered variety) so far in ethiopia. in a similar kind of study, melito et al. (2017) found that 48% of the genotypes from a total of 27 populations which produced from seven biparental crosses/families that showed higher total tuber yield compared to the standard check. the highest mean tuber number per plant and marketable tuber number recorded from biparental crosses of jalene and ater ababa whereas the maximum mean of tuber yield per plant, average tuber weight and unmarketable tuber yield found in crosses of gera x shenkola variety (table 4). in addition, potato genotypes (offsprings) produced from belete cross with ater ababa manifested highest mean for marketable tuber yield and total tuber yield. this may be due to over dominance of maternal effect which belete (female parent) is high yielder variety in the country. tuber size distribution such as proportion of small tubers, medium tubers and large tubers ranged from 5.86 to 59.07; 26.8 to 81.08; and 0.6 to 55.67%, respectively (table 4). the maximum mean percentage of small tubers and large tubers were noted from progenies of jalene and ater ababa (41) and gera and shenkola accordingly. the maximum proportion of small tubers (59.07%) showed by genotype j x a.333 whereas, genotype ge x sh.206 and parental varieties such as shenkola and belete variety exhibited significantly highest percentages of large tubers. proportion of quality traits (tuber dry matter and starch content) ranged from 13.78 to 29 and 8.2821.84% (table 4). these results agree with the findings of garnica et al. (2012) who reported tuber dry matter and starch content (%) that ranged from 22.1 to 28.06 and 15.86 to 21.51%, respectively. but higher than explained by tesfaye abebe et al. (2012) who evaluated 25 released potato varieties and the varieties overall values ranged from 17.65 to 26.70% dry matter content and 9.75 to 17.82% for total starch content under adet environment. potato offsprings of belete and ater ababa produced higher mean tuber dry matter yield and tuber starch content (%) than other biparental crosses. significantly lower tuber dry matter and starch content (%) were recorded from crosses of gera and shenkola variety by genotype ge x sh.186. individual genotypes b x a.97 and j x a.266 showed higher tuber dry matter yield and starch content than all other clones. the results may be due to positive correlation of dry matter content with total starch content (r=1**) as observed in this study and suggests that continuous evaluation of these crosses may result in a higher chance of obtaining genotypes with high tuber quality traits. a total of forty (40) potato offsprings and four parental varieties produced the maximum percentages of tuber dry matter yield and starch content than the standard check variety. the present findings are also supported by results of previous workers. addisu fekadu et al. (2013) reported availability in tuber size distribution that ranged from 4.6 to 56.67% for small sized tubers, 27.80 to 49.00% for medium sized tubers and 0.5 to 65.7% for large sized tubers. melito et al. (2017) also reported the possibility of obtaining many genotypes with better tuber yield from bi-parental crosses. similarly, hajianfar et al. (2017) reported as high as 11.96, 41.22 and 37.19 t ha-1 tuber number per plant, total tuber yield, and marketable yield, respectively, and tuber dry matter up to 26.7% in hybrids of potato genotypes. in addition, luthra et al. (2017) observed the range from 6.23 to 10.34 for tuber number per plant, 20.2 to 36.6 for marketable yield, 23.7 to 38.8 for total yield t ha-1 and 13.9 to 18.5% for dry matter from potato progenies. additionally, parmar et a l. (2015) showed tuber yield per plant 249.15 to 511.07gm and average tuber weight 48.53 to 98.2gm among 32 potato progenies. furthermore, nizamuddin et al. (2010); zakerhamidi (2014) and nickmanesh and hassanpanah (2014) reported a wide range of tuber yield in progenies of two varietal crosses. feltran et al. (2004) reported high dry matter and starch content ranged from 15.7 to 22.4% and 56.7 to 71.4%, respectively, in 18 potato cultivars. in family base, the maximum proportion in 41 potato offspring obtained from crossing jalene with aterababa showed semi-erect growth habit (39.02%), light pink flower color (80.49%), brown tuber skin color (29.27%), yellow tuber flesh color (44.34%), medium tuber eye depth (39.02%), smooth skin type manamno et al. genetic variability among potato progenies 7 (58.54%), oval tuber shape (39.02%) and intermediate (5<20) eye numbers(39%). on other hand, most proportion of potato offsprings/genotypes derived from belete and ater ababa contained decumbent growth habit (45.83%), light pink flower (58.33%), brown tuber skin color (37.5%), yellow tuber flesh color (41.67%, medium tuber eye depth (54.16%), smooth tuber skin type (70.8%), round and long tuber shape (60%) and inter mediate tuber eye number (91.67%). however, the proportion of the genotypes generated from gera cross shenkola observed decumbent (45.83%) growth habit, light, and intense purple flower color (100%), light brown (30%) and white tuber skin color (50%), light yellow tuber flesh color (40%), light yellow tuber flesh color (40%) for each) and oval tuber shape (70%) in this study. according to kumar et al. (2018) white-fleshcolored potatoes are low in carotenoids (<100μg/100 g fresh weight) whereas the carotenoids content of yellow-fleshed varieties is higher (about 560μg/100 g fw). intense yellow to near orange flesh color is associated with carotenoid concentrations >2000μg/100g. based on this information, about 33 from a total of 75 potato progenies showed white and cream flesh color which is low in carotenoids, while other genotypes contained yellow and different flesh color which had high carotenoid content. cultivars which possess either shallow or medium eye depths are perfect to reduce losses during peeling and trimming. therefore, the results of crossing belete and ater ababa produced large proportion of skin type highly desired for any french frying or processing industries and as such considering these parental materials seems essential to producing clonal population targeting processing industries. hence, genotypes in this study showed difference by morphological qualitative traits not only among all families but also with in biparental crosses. 3.2. genetic variability components 3.2.1. phenotypic and genotypic coefficients of variations the variability components (phenotypic and genotypic variances and coefficient of variations, heritability in broad sense and genetic advances as percent of mean) were estimated for agro morphological traits (table 5). the estimates of genotypic and phenotypic coefficient of variations were computed in the range between 3.25 to 51.41 and 4.67 to 60.28%, respectively. the lowest and the highest values were computed for days to maturity and number of large tubers, respectively. according to siva subramanian and menon (1973), pcv and gcv values roughly more than 20% are high, whereas values less than 10% are low and values between 10 and 20% to be medium. correspondingly, days to flowering, plant stem height, average tuber weight, marketable tuber number, marketable tuber yield and total tuber yield exhibited high phenotype and genotypic variance indicating greater scope of selection for the improvement of these characters. similarly, haydar (2009) reported the maximum genotypic and phenotypic variance for plant height. hajam et al. (2018) also observed highest gv and pv for average tuber weight, tuber yield per plant and total tuber yield, and in addition, benavente and pinto (2012) found high genotypic variance for total tuber yield from among families and within families in 30 potato genotypes which produced by biparental crossing. maximum phenotypic coefficients of variation (pcv) was computed for main stem number, tuber number per plant, average tuber weight, tuber yield per plant, marketable tuber number, marketable yield, total tuber yield, tuber starch content and percentages of small tubers and large tubers whereas highest genotypic coefficients of variation (gcv) had observed for traits such as main stem number, tuber number per plant, average tuber weight, tuber yield per plant, marketable tuber number, marketable yield, total tuber yield, percentages of small tubers and large tubers. in line with this study, ozturk and yildirim (2014) reported high genetic coefficient of variation (gcv) for total yield (26.2 %), plant height (21.2 %) and average tuber weight (20.4 %) for genotypes. the characters having high gcv indicate high potential for effective selection (burton, 1957). characters with high genetic variability and genetic advance are also important for selecting the desirable parents (biswas et al., 2005). high estimates of phenotypic (pcv) and genotypic coefficients of variation (gcv) were observed for main stem number, tuber number per plant, average tuber weight, tuber yield per plant, marketable tuber number, marketable tuber yield, total tuber yield, small tuber, and large tuber percentage. the result was agreed with authors such as hajam et al. (2018), noted highest gcv and pcv for traits number of main stems, total tuber yield and tuber yield per plant. the traits which exhibited high estimates of genotypic and phenotypic coefficient of variations had high probability of improvement through selection to develop new variety (singh, 1990). moderately high phenotypic (pcv) and genotypic coefficients of variation (gcv) were computed for plant stem height, days to 50% flowering and tuber dry matter. moderate phenotypic coefficients of variation (pcv) were also noted for days to 50% emergency. abraham lamboro (2014) reported moderately high pcv and gcv for plant stem height, percentage of small tubers and days to emergence. low estimates of pcv and gcv were obtained for days to maturity. this agrees with kameshwari (2015) who reported the lowest gcv and pcv for days to maturity. the lowest gcv and pcv suggested that selection for the desired character based on phenotypic expression of genotypes might not be effective in attaining the desired genotypes due to the highest masking of factors to express these traits. singh (1990) also reported low gcv and pcv values for dry matter content. manamno et al. east african journal of sciences volume 15 (1) 1-16 8 table 4. average family mean values (range) of evaluated genotypes for quantitative traits. family no. of clone range df ma sn sh tnp typ atw mtn my unm ty vsn ltn dm sc j x a 41 min 44 88 3 33.1 7 0.23 16.61 66 6.58 0.33 10.8 6.25 0.6 14.13 8.59 max 53 101 9 66 25 0.97 71.38 247 43.8 8.19 44.1 59.1 40.29 27.68 20.67 mean 48 95 5 49.2 14 0.59 42.27 144 23.3 3.7 27.0 30 18.14 21.18 14.88 b x a 24 min 42 88 2 32.3 6 0.27 26.45 75 8.73 1.05 11.7 5.86 3.2 15.63 9.93 max 55 102 6 73.3 23 1.03 78.1 226 55.6 7.65 58.3 42.5 49.78 29.00 21.84 mean 46 95 4 46.6 12 0.62 53.55 130 26.9 3.4 30.3 23.3 27.23 21.73 15.36 ge x sh 10 min 46 90 3 41.3 8 0.3 35.11 13.5 2.51 0.58 16.8 13.2 12.6 13.78 8.28 max 60 99 7 71.6 17 1.03 103.3 193 33.9 24.9 45.7 52.2 55.47 25.48 18.7 mean 50 94 5 53.9 12 0.63 56.49 118 21.7 7.51 29.2 27.2 27.61 21.57 15.22 jalene 1 mean 54 93 4 50.2 15 0.6 40.96 135 23.0 4.41 27.4 36.3 17.81 18.15 12.18 aterababa 1 mean 45 91 4 48.1 13 0.49 39.32 108 17.1 5.34 22.4 34.9 13.19 22.18 15.76 belete 1 mean 48 99 2 52.9 8 0.88 106.8 111 41.0 1.66 42.6 13.2 55.67 24.3 17.66 gera 1 mean 52 99 2 65.8 13 0.89 72.87 157 37.1 2.23 39.3 14.3 41.31 20.98 14.69 shenkola 1 mean 55 101 2 66.6 10 0.82 82.11 127 36.0 1.6 37.6 16.9 55.59 23.75 17.17 dagim 1 mean 48 92 2 57.4 10 0.43 48.94 105 16.4 2.47 18.9 20.4 31.86 21.3 14.99 g.mean 48 95 4 49.3 13 0.6 48.74 135 24.5 3.9 28.0 27.0 23.0 21.47 15.14 note: j x a = jalene cross with ater ababa, b x a = belete cross with ater ababa, ge x sh= gera cross with shenkola, dagim = standard check variety, min=minimum, max = maximum, g.mean=grand mean, de = days to emergency, df = days to 50% flowering, dma = days to 90% maturity, sn = main stem number, sh (cm) = stem height, tnp = tuber number per plant, typ (g) = tuber yield per plant, aw (g) = average tuber weight, mtn = marketable tuber number, my = marketable yield(t ha -1), unmy = unmarketable yield (t ha-1), ty = total yield(t ha-1),vsn = very small tuber size percentage, mdn = medium tuber size percentage, ltn = large size tuber percentage, dm=tuber dry matter content (%), sg = specific gravity of tuber, and sc = tuber starch content (%). manamno et al. genetic variability among potato progenies 9 on this study, the pcv values were slightly higher than their corresponding gcv values for all the characters considered which reflect a little influence of environment on the expression of characters. this agrees with getachew assefa et al. (2016) and biswas (2005) reported high phenotypic variances than genotypic variances for growth and yield traits in genotypes. 3.2.2. heritability and genetic advance estimate of heritability in broad sense ranged from 28.81 to 91.64% for percentages of small sized tubers and days to flowering, respectively (table 5). as suggested by pramoda (2002), h2b estimates is categorized as low < 40%, medium 40-59%, moderately high (60-79) and very high (>80%). based on this category, very high heritability estimate was noted for days to flowering (91.64%), tuber yield per plant (80%) and average tuber weight (80.45%) indicating the selection of genotypes for such characters could be easy and may lead to the improvement of the mean values in selected genotypes for those traits. presence of high heritability indicated that these traits are less influenced by environmental fluctuations and governed by the additive gene effects that are substantially contributing towards the expression of traits. similarly, ozturk and yildirim (2014) reported the highest board sense heritability’s for average tuber weight, moussa (2013) noted high estimates of heritability for tuber yield per plant from 17 potato genotypes comprising seven parents and their ten crosses, and haydar (2009) also reported high heritability for tuber yield per plant and tuber numbers per plant respectively from seven potato parent and hybrids. high heritability coupled with high genetic advances was computed for average tuber weight indicating the influence of additive gene effect on the trait. hence, these traits can be improved through simple selection. effectiveness of selection is considered more reliable when heritability is coupled with genetic advance. the result was in close agreement with the findings of moussa (2013) and biswas (2005) who reported that high heritability value along with high genetic advance for average tuber weight in potato hybrids. moderately high heritability was also ranged between 72.75 and 77.86% for stem height, tuber number per plant, marketable tuber yield, total tuber yield and proportions of large sized tubers while medium heritability showed for days to emergency, days to maturity, marketable tuber number, tuber dry matter and tuber starch content percentage. in line with this study, mishra et al. (2017) obtained moderately high heritability for marketable yield (77.1%), total tuber yield (76.8%) and tuber dry matter from hybrids. low heritability value noted for small tuber size (28.81%). this indicates that selection may be considerably difficult or virtually impractical due to the masking effect of the environment. high heritability accompanied with low genetic advances was recorded for tuber yield per plant. this suggested that the character was influenced due to favorable influence of environment or predominant effects of non-additive gene rather than genotypes. panse (1957) reported that low heritability accompanied with genetic advance is due to non-additive gene effects for the particular trait. as stated, panes and sukhatme (1964), high heritability values associated with equally high genetic advance is chiefly due to dominance and epistasis. the genetic advance as percent mean was categorized as low (<10%), moderate, (10-20%) and high (>20%) by johnson et al. (1955). based on these categories, the highest genetic advance for tested genotypes expressed as percentage of the mean (gam) showed for all traits ranging from 25.08 to 90.33% except for days to emergency, days to maturity, percentages of tuber dry matter and tuber starch content (table 5). traits which showed high values of genetic advance might be due to additive gene action. similarly, kameshwari (2015) reported high genetic advance in percentage of mean for average tuber weight and tuber yield per plant. manamno et al. east african journal of sciences volume 15 (1) 1-16 10 table 5. variability components for 16 traits of evaluated 81 genotypes and parental varieties. trait range mean σ2g σ2p gcv (%) pcv (%) hb (%) ga (5%) gam (5%) days to emergence 16-24 18.12 2.95 5.20 9.47 12.58 56.65 2.66 14.68 days to flowering 42-60 61.00 36.97 40.35 12.72 13.28 91.64 11.99 25.08 days to maturity 88-102 94.51 9.41 19.48 3.25 4.67 48.3 4.39 4.65 stem height(cm) 32.27-73.33 49.34 73.19 95.66 17.34 19.82 76.51 15.42 31.24 main stem number 2.0-9.0 3.80 1.08 2.04 27.23 37.43 52.9 1.56 40.79 tuber number/plant 6.0-25.0 12.93 12.69 17.48 27.55 32.33 72.63 6.26 48.37 average tuber weight(g) 16.61-106.83 48.74 261.72 325.32 33.20 37.01 80.45 29.89 61.33 tuber yield /plant(kg) 0.23-1.03 0.60 0.04 0.05 32.63 35.79 80.00 0.37 61.26 marketable tuber number 11-310 134.5 1412.61 2503.7 27.94 37.19 56.42 58.16 43.23 marketable yield t ha-1 2.51-55.62 24.46 87.61 112.52 38.26 43.36 77.86 17.01 69.55 total yield t ha-1 10.82-58.31 28.32 81.94 108.01 31.97 36.7 75.87 16.24 57.36 tuber dry matter 13.78-29 21.47 6.23 14.47 11.62 17.72 43.02 3.37 15.7 tuber starch content 8.28-21.84 15.14 4.94 11.49 14.69 22.39 43.04 3.01 19.85 small tuber 5.86-59.07 26.89 61.36 212.99 29.13 54.27 28.81 8.66 32.2 large tuber 0.6-55.67 49.99 141.26 194.18 51.41 60.28 72.75 20.88 90.33 note: σ2g = genotypic variance, σ2p = phenotypic variance, pcv (%) = phenotypic coefficient of variation (%) = genotypic coefficient of variation, hb (%) = heritability in broad sense, ga = genetic advance, and gam = genetic advance as percent of mean. manamno et al. genetic variability among potato progenies 11 3.2.3. phenotypic and genotypic correlations the estimates of genotypic and phenotypic correlation coefficients between total tuber yield and all possible pairs of yield components are presented in table 6. phenotypic and genotypic association of days to emergency with days to flowering was positive. this indicates that selection for this trait may lead to early mature genotypes. days to emergency was negatively correlated with main stem number, tuber number per plant and marketable tuber number at phenotypic and genotypic levels but, positively correlated with proportion of large tuber size at both levels. plant stem height positively correlated with tuber yield per plant, tuber number plant, average tuber weight, marketable tuber number, marketable tuber yield, total tuber yield, tuber dry matter, tuber starch content and proportion of large tuber sized tubers at both correlations level but, it correlated negatively with proportion of small tuber size at genotypic level. total tuber yield showed positive genotypic and phenotypic association with days to maturity, tuber number per plant, average tuber weight, marketable tuber number, tuber dry matter, tuber starch content and proportion large tuber size but showed negative association with proportion of small tuber sizes. both marketable tuber yield and total tuber yield were positively correlated with plant stem height, tuber yield per plant, tuber number per plant, marketable tuber number and average tuber weight, tuber dry matter, tuber starch content and proportion of large tuber numbers at phenotypic level. these positive correlations indicating that selection for improving one character will lead to increase the other one which is positively correlated with that character. in contrast, marketable tuber yield and total tuber yield were negatively correlated with proportion of small tuber sizes. in similarly with abraham lamboro et al. (2014) and addisu fekadu et al. (2013) who reported highly significant negative correlation of total tuber yield with proportion of small sized tubers at genotypic and phenotypic level. negative correlation between two traits implies selection for improving one character will likely cause decrease in the other traits. in present study the tuber dry matter had exhibited strong phenotypic and genotypic correlation (r = 1) with tuber starch content. this suggested that the simple selection to improve one trait simultaneously increase the second character. similarly, highly significant correlation was reported for dry matter and tuber starch content by wassu mohmmad (2016) who observed the correlation was near to perfect (r = 0.97 to 0.99) and khayatnezhad et al. (2011) that reported stronger positive and significant correlations between starch content and dry matter content. generally, in most of traits genotypic correlation was higher than phenotypic correlation indicating an inherent association between various characters. this agrees with addisu fekadu et al. (2013) who reported higher genotypic correlation than phenotypic correlation. the main genetic cause of such correlation is pleiotropy, which refers to manifold effects of a gene (falconer, 1989). above results were similarly reported by tripura et al. (2016) who found tuber number per plant have positive and significant association with total tuber yield. panigrahi et al. (2017) reported that total tuber yield showed positive and significant correlation with marketable tuber yield at both phenotypic as well as at genotypic levels. sattar et al. (2007) reported tuber yield per plant was positively and significantly correlated with number of tubers per plant, average tuber weight and dry matter content of tuber. he also showed the significant positive genotypic correlation of average weight of tubers with number of tubers per plant, yield of tuber per plant and tuber dry matter percentages. manamno et al. east african journal of sciences volume 15 (1) 1-16 12 table 6. genotypic (above diagonal) and phenotypic (below diagonal) correlation coefficients for different pairs of traits in potato. trait de df dma sh sn typ tnp aw mtn my ty dm sc smn lsn de 1 0.24* 0.14 -0.21 -0.4** -0.15 -0.26* 0.1 -0.24* -0.09 -0.09 0.07 0.07 -0.09 0.14 df 0.21* 1 -0.07 0.1 -0.15 0.11 0.01 0.15 0.00 0.12 0.14 0.05 0.05 -0.014 0.23* dma 0.04 -0.03 1 0.02 0.02 -0.03 0.07 0.02 0.04 0.07* 0.11* -0.03 -0.03 0.09 0.07 sh -0.17* 0.07 -0.02 1 0.1 0.102 0.73** 0.36** 0.43** 0.67** 0.71 ** 0.41** 0.41** -0.30* 0.43** sn -0.29* -0.13 -0.04 0.07 1 0.13 0.53** -0.36** 0.42** 0.08 0.1 0.04 0.04 0.19 -0.39** typ -0.12 0.09 0.02 0.69** 0.11 1 0.5** 0.49 ** 0.61** 0.91** 0.97** 0.54** 0.54** -0.4** 0.54** tnp -0.2* -0.00 -0.02 0.35** 0.45** 0.5** 1 -0.35* 0.8** 0.39* 0.47** 0.38* 0.38* 0.23* -0.35* aw 0.08 0.13 0.03 0.38** -0.3** 0.59** -0.36** 1 -0.03 0.35* 0.59** 0.25* 0.25* -0.58** 0.90** mtn -0.23* -0.02 -0.23* 0.38** 0.34** 0.57** 0.71** -0.05 1 0.7** 0.64** 0.47** 0.47** -0.36* -0.01 my -0.10 0.10 0.05* 0.61** 0.06 0.89** 0.41** 0.54** 0.67** 1 0.95** 0.52** 0.52** -0.56** 0.61** ty -0.08 0.11 0.06* 0.68** 0.07 0.95** 0.49** 0.54** 0.54** 0.93** 1 0.56** 0.56** -0.40* 0.57** dm -0.06 0.04 0.03* 0.31** 0.05 0.45** 0.3** 0.21* 0.38** 0.44** 0.45** 1 1.00** -0.21 0.18 sc -0.06 0.04 0.03* 0.31** 0.05 0.45** 0.3** 0.21* 0.38** 0.44** 0.45** 1.0** 1 -0.21 0.18 smn 0.08 0.01 -0.04 -0.14 0.08 -0.23* 0.16* -0.39** -0.52** -0.4** -0.20* -0.21* -0.21* 1 -0.64** lsn 0.1 0.21* 0.05 0.39** -0.35 0.51** -0.34** 0.87** -0.03 0.57** 0.53** 0.14 0.14 0.14 1 note: *and **, significant at p<0.05 and p<0.01, respectively, de = days to emergency, df = days to flowering, dma = days to maturity, sh = plant stem height, sn = main stem number, typ = tuber yield per plant, tnp=tuber number per plant, aw = average tuber weight, mtn = marketable tuber number, my = marketable yield, unmy = unmarketable yield, ty = total tuber yield, smn = very small tuber size percentage, lsn = large size tuber percentage, dm = tuber dry matter content (%) and sc = tuber starch content (%). manamno et al. genetic variability among potato progenies 13 4. conclusions genetic variability is the base for the crop improvement. the availability of more diverse current materials obtained from local crossing indicated the chance of getting desirable genes to improve the potato crop. hence, potato offspring generated from hybridization of cultivated potato varieties showed genetically variability in yield and its related traits and morphological traits in the current study. the high range and mean values of the evaluated parental varieties and progenies also suggest that the existence of enough variability correlations of traits. biparental crosses of jalene with aterababa and belete with aterababa varieties produced more promising/better genotypes than the crosses of gera and shenkola, and standard check variety in yield and yield related traits. so, the result of this study also indicated the continuously producing more diverse clones by local crossing can reduce dependency on international potato center materials in the country. therefore, additional experiments will be carried out to evaluate the most promising genotypes for desirable traits, with the purpose to either produce new variety or select parental lines for further breeding. 5. acknowledgments we are indebted to amhara regional agricultural research institute (arari) and adet agricultural research center for the financial support that enabled us to do the research. 6. references abraham, 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16 ©haramaya university, 2021 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2021) volume 15(2): 167-174 licensed under a creative commons *corresponding author: belaym2012@gmail.com attribution-noncommercial 4.0 international license. effects of applying blended mineral nps and nitrogen fertilizers on growth, yield components, and yield of maize (zea mays l.) in fedis district, eastern ethiopia mekuannet belay kebede* and habtamu zeleke utta school of plant sciences, haramaya university, p.o. box 138, dire dawa, ethiopia abstract background: maize is the major and most important cereal crop next to sorghum in eastern ethiopia. however, the yield of the crop is low mainly due to low inherent soil fertility and poor soil fertility management practices. objective: field experiments were conducted during the main rainy cropping season in 2018 and 2019 to assess the effect of blended mineral nps and n fertilizer on growth, yield components, and yield of maize varieties. materials and methods: the treatments consisted of two open-pollinated maize varieties (baate and melkasa2), three blended nps fertilizer rates (50, 100 and 150 kg nps ha–1), and three nitrogen fertilizer rates (43.5, 87 and 130.5 kg n ha–1). the experiments were laid out as a randomized complete block design in a factorial arrangement and replicated three times per treatment. results: the results showed that leaf area index, plant and ear height, ear diameter, number of kernels per ear, and grain yield were significantly affected by the interaction effects of variety, nps fertilizer, and year. the maximum ear diameter and the number of kernels per ear were produced from the baate variety in response to the application of 100 and 150 kg nps ha–1in the 2019 cropping season. besides, the highest aboveground biomass yield (18.5 t ha–1) was obtained from the variety baate treated with 150 kg nps and 130.5 kg n ha–1. the maximum grain yield (8.0 t ha–1) was obtained from the baate variety in response to the application of 150 kg ha–1 nps in the 2019 cropping season. the application of 87 kg n ha–1 produced a high grain yield, which was also found to be economically feasible for both varieties. the partial budget analysis also affirmed that the highest net benefit (44850.0 etb) with the higher marginal rate of return (764%) was obtained from baate variety supplied with 150 kg nps ha–1, which was economically more feasible than melkasa-2 variety with the application of 150 kg nps ha–1(6.7 t ha–1 ). conclusion: it is concluded that cultivating the baate maize variety with the application of 150 kg nps fertilizer ha–1 and 87 kg n ha–1 was found to be economically optimum for smallholder farmers in the study area to enhance productivity of the crop. keywords: baate; economic analysis; fertilizer rate; melkasa-2; yield related traits 1. introduction maize plays a significant role in the overall economy and food security and covers nearly 197, 204, 250 million hectares of the world’s arable land (faostat, 2019). it is also the most widely grown staple food crop in eastern africa occupying more than 15.7 million ha (fao, 2019). maize is the second most widely cultivated crop in ethiopia next to tef and is grown under diverse agroecologies and socioeconomic conditions (tsedeke abate et al., 2017). according to a report of the central statistical agency (2020), around 17.68% of ethiopian cultivated land is covered by maize and its national average yield is 4.2 t ha–1. similarly, it is the second most important staple food crop next to sorghum in the eastern hararghe zone of ethiopia and its average yield is 3.5 t ha–1 (csa, 2020). however, the average yield of maize in eastern hararghe, in particular, is 3.5 t ha–1 and that in the country is 4.2 t ha– 1 (csa, 2020), both of which are lower than the world’s average yield of 5.8 t ha–1 (fao, 2019). the low productivity of maize in ethiopia is attributed to many factors like biotic, abiotic, and poor agronomic practices. poor soil fertility is one of the bottlenecks for sustaining maize production and productivity in ethiopia. most ethiopian soils are deficient in nutrients especially nitrogen and phosphorus (tekalign mammo et al., 2001) due to the removal of crop residue and animal dung by small scale farmers for competing ends such as fuelwood and construction of houses (ifpri, 2010). in addition, over-cultivation, insufficient inputs of replacement nutrients, accelerated soil erosion caused by inappropriate land uses and poor soil management practices as well as unbalanced fertilization also aggravates soil nutrient depletion which adversely affects crop production and consequently poses a potential threat to global food mailto:belaym2012@gmail.com mekuannet and habtamu east african journal of sciences volume 15(2): 159-174 168 security and agricultural sustainability (tan et al., 2014). therefore, application of appropriate types and rates of commercial fertilizers have been credited with nearly 50% of crop yield increments (stewart et al., 2005). however, smallholder farmers have been applying di-ammonium phosphate (dap) and urea at lower rates because of the constantly increasing prices of fertilizers. besides, smallholder farmers have been also applying blanket recommendations of dap and urea that do not consider soil fertility status and crop requirements and are often sub-optimal. a recent soil mapping report by ethiosis (2014) has shown that sulfur is deficient in most ethiopian soils including some parts of eastern ethiopiain addition to phosphorus and nitrogen. therefore, the ethiopian ministry of agriculture has recently introduced the blended nps fertilizer for use in the study area and other similar areas particularly in place of dap fertilizer (moanr, 2013). however, the recommended rate of blended nps to open-pollinated maize variety has not described and the combined effect of blended nps and nitrogen on maize production particularly in the study area has not been well studied so far. nevertheless, some field experiments conducted on few maize varieties in some other areas. for instance, a field experiment conducted in haramaya (raare) district has confirmed that the highest grain yield of a hybrid maize variety was obtained in response to the combined application of 150 kg nps and 87 kg n t ha–1 (mekuannet belay and kiya adare, 2020). dagne chimdessa (2016) also reported that in western oromia, the application of blended fertilizers increased maize productivity compared to the previously applied recommended mineral nitrogen (urea) and phosphorus (di-ammonium phosphate). similarly, the application of nps and urea significantly increased the grain yield of maize in the west gojjam zone of ethiopia as compared to the blanket recommendation of dap + urea (mesfin et al., 2019). mekuannet belay (2020) reported that the responses of yield and yield components of maize varieties to blended nps and urea varied in different seasons. however, in most cases, the small scale farmers have been applying 100 kg nps with 150 kg urea ha−1 for different soils types and maize (open and hybrid) varieties as a blanket recommendation albeit the response of maize plant to application fertilizer rates vary from variety to variety, location to location, and also depends on the availability of the nutrients (onasanya et al., 2009). therefore, the relevance of this experiment was to determine optimum blended mineral nps and nitrogen fertilizer rates for baate and melksasa 2 maize varieties and recommend to the farmers as well as other stalk holders to improve production in the study area and other similar agroecologies. in the eastern hararghe zone particularly in fedis district, not sufficient research has been done to investigate the effect of blended nps as well as mineral nitrogen and phosphorus fertilizers (dap and urea). as a result, there is no documented information on responses of yield and yield-related traits of maize to combined blended mineral nps and nitrogen fertilizer rates. therefore, this study was conducted to assess the effect of applying blended mineral nps and nitrogen fertilizer rates on growth, yield components, and yield of open-pollinated maize varieties. 2. materials and methods 2.1. description of the experiment site experiments were conducted under rain-fed conditions during the main cropping season for two consecutive years (2018/19 and 2019/20) at a research sub-station of haramaya university in fedis district of oromia regional state of the east hararghe zone in ethiopia at a place called beko. geographically, fedis is located at the latitude of 9˚07'51.6"n and longitude of 42˚04'24.3"e. the area has an average altitude of about 1702 meters above sea level. the soil texture of the experimental site is sandy. in the 2018 main cropping season, the mean maximum and minimum temperatures of the district during the season of the experiment were 28.0 and 14.0 °c, respectively; the total annual rainfall was 750 mm. in the 2019 main cropping season, the mean maximum and minimum temperatures were 28.3 and 13.4 °c, respectively, and the total annual rainfall was 516.3 mm (figure 1). mekuannet and habtamu effects of blended nps and n rates on yield of maize 169 figure 1. total monthly rainfall (mm), mean maximum and minimum temperatures (°c) at fedis in the 2018 and 2019 cropping season (fedis agricultural research center meteorological station, 2019). 2.2. description of experimental materials 2.2.1. planting material maize varieties named baate and melkasa-2 were used as test crops. the plant height and ear height of the baate variety reach 180 cm and 95 cm, respectively, and the number of days required to reach maturity is 145 days. on the other hand, the plant height and ear height of the melkasa-2 variety are also 150 cm and 70 cm, respectively, and the number of days required maturity is 130 days. baate variety was released by haramaya university in 2017. melkasa-2 variety was released by melkassa agricultural research center in 2004. baate variety is adaptable to mid and high altitude areas. the elevation at which baate variety grows best ranges from mid to highland areas, which is 1300 to 2000 meters above sea level`. baate variety is adaptable to mid and high altitudes. melkasa-2 variety is adaptable to mid and low altitudes. the elevation at which it grows best ranges from low to midland areas, which is 500 to 1800 meters above sea level. regarding yield potential, baate variety can produce grain yield that ranges between 4.5 to 6.0 t ha–1 on-station but 3.5 to 4.5 on farmers’ field. melkasa-2 variety has a slightly higher yield potential which ranges between 5.5 to 6.5 t ha–1 on-station but 4.5 to 5.5 on farmers’ field (moa, 2019). 2.2.2. fertilizer material urea was used as a source of nitrogen (100 kg urea = 46% n) and blended nps was also used as a source of phosphorus, nitrogen and sulfur. one hundred kilograms of nps fertilizer contains 19% n, 38% p2o5 and 7% s per 100 kg. 2.3. treatments and experimental design the treatments consisted of two open-pollinated maize varieties (baate, melkasa-2), three rates of nps fertilizer (50, 100 and 150 kg ha–1), and three rates of nitrogen fertilizer (43.5, 87 and 130.5 kg n ha–1). the blanket recommendation rates of urea (150 kg urea or 87 kg nha– 1) and blended nps (100 kg ha–1) were used as control treatments. the experiment was laid out as a randomized complete block design (rcbd) with three replications per treatment. treatments were assigned to each plot randomly. the gross and net plot areas were 12.6 m2 and 6.3 m2, respectively. each plot had four rows with two central rows used for data collection and analysis and the side row of each plot were left as a border effect. the spacing between rows and plants was 75 and 30 cm, respectively. 0 5 10 15 20 25 30 35 0 50 100 150 200 ja n u ar y f e b ru ar y m ar c h a p ri l m ay ju n e ju ly a u g u es t s ep te m b e r o ct o b er n o v e m b e r d e c e m b e r t e m p e ra tu re ( °c ) r ai n fa ll ( m m ) month total monthly rainfall (mm) in 2018 total monthly rainfall (mm) in 2019 monthly mean max. temp (°c) in 2018 monthly mean max. temp (°c) in 2019 monthly mean min. temp (°c) in 2019 monthly mean min. temp (°c) in 2018 mekuannet and habtamu east african journal of sciences volume 15(2): 159-174 170 2.4. soil sampling and analysis before sowing, soil samples were taken randomly to the depth of 0–30 cm from 15 spots of the experimental field. the collected soil samples were composited to one sample and air-dried, ground, and sieved using a 2 mm sieve to prepare for laboratory analysis. the samples were analyzed for soil texture, ph, organic carbon (oc), total nitrogen (tn), available phosphorus, and cation exchange capacity (cec) using the following standard analytical procedures. soil ph was measured using a glass electrode ph meter in a supernatant of 1:2.5 soils to a solution ratio of h2o. organic carbon of the soils was determined following the wet digestion method as described by walkley and black (1934). total n of the soil was determined through digestion, distillation and titration procedure of the kjeldahl method as described by jackson (1967). available p content was measured after bray (1945). the cation exchange capacity was determined according to jackson (1967) method. sulfur soil laboratory analysis was not done due to lack of chemicals in central soil laboratory analysis of haramaya university, however, some parts of eastern ethiopia soils are found to be low in sulfur content as reported by ethiosis (2014) and as a result, blended nps fertilizer is introduced in place of di-ammonium phosphate (dap) (moanr, 2013). selected soil physical and chemical properties the results of the laboratory analysis of the selected physical and chemical properties of soils of fedis research station are presented in table 2. the textural class of the soils sandy based on the soil textural triangle of the international society of soil science (isss) system (rowell, 1994). the ph of the experimental soil is 7.48 which are slightly alkaline based on ph limit (7.4 to 7.8) as described by (jones, 2003). the ph is in the range of 6.0 to 7.5 favourable for maize production. table 2. soil physical and chemical properties of the experimental field before sowing. analysis result rating reference sand (%) 80 silt (%) 5 clay (%) 15 texture sand ph (1:2.5 soil/water) 7.48 slightly alkaline jones (2003) available p (mg kg soil–1) 16.77 medium cottenie (1980) oc (%) 2.3 medium tekalign tadesse (1991) total n (%) 0.11 low murphy (1968) cec (cmol(+) kg soil–1) 15.86 medium hazelton and murphy (2007) 2.5. experimental procedures the land was ploughed, disked and harrowed by a tractor. field leveling was done manually before sowing. then, two seeds were sown per hole on 15 june 2018 and on 20 june 2019 and covered with soil manually. thinning to a single plant per hill was done when seedlings produced three to four leaves. the full dose of nps and half (½) of the n fertilizer was applied at sowing while the remaining half (½) was applied at the knee height stage of growth as side-dressing (tadesse tilahun et al., 2013). hand weeding and cultivation were done throughout the growing season manually. spraying the insecticide (fastac) was also carried out to protect the plants from the fall armyworm (spodoptera frugiperda). harvesting of the two central rows of each plot was carried out manually with a sickle at the end of the month of october in both years. 2.6. data collection growth variables the leaf area index was determined as the ratio of leaf area per plant divided by the respective ground area occupied by the plant. plant height was measured from ten randomly pre-tagged plants from the net plot area and then their height was measured from the soil surface to the point where the tassel started to branch with a meter rod at physiological maturity. ear height was recorded from ten randomly pre-tagged plants from each net plot area and the ear height was measured from the ground level to the node bearing the top useful ear with a meter rod at physiological maturity (cimmyt, 1985). yield components and yield the number of ears plant–1 was taken from ten randomly pre-tagged plants in the net plot area, and then their ears were counted at harvest and the average was recorded. ear length was recorded from ten randomly taken ears from the net plot area and measured from the point where ears were attached to the stalk to the tip of the ear with a glass ruler after harvest and the average was recorded. ear diameter was recorded from ten randomly taken ears from the net plot area, and then their diameter was measured at the middle of the ear with a caliber ruler. the number of mekuannet and habtamu east african journal of sciences volume 15 (2) 159-174 171 kernels per ear was recorded by multiplying the total number of rows per ear and the number of kernels per row from five randomly taken ears in the net plot area after harvest and the average was recorded. a thousand kernels were counted from randomly taken ears after shelling by using a kernel counter. then, the thousand kernel weight was recorded by weighing a thousand kernels using a sensitive balance and adjusting the moisture level to 12.5%. aboveground dry biomass yield was weighed after the entire plants were harvested from the net plot area, weighed using field balance. grain yield from the net plot area was weighed using a field balance after adjusting the moisture content to 12.5%. the harvest index was calculated as the ratio of grain yield to the total aboveground dry biomass yield per plot × 100 (cimmyt, 1985). 2.7. data analysis all data were subjected to analysis of variance (glm procedure) using genstat software program version 17th (vsn international, 2012). homogeneity of variances was evaluated using the f-test as described by fisher (1935). since the f-test results of most agronomic parameters of the two-seasons data depicted homogeneity of variances, a combined analysis was done. the fisher’s protected least significant difference (lsd) test at 0.05 probability level was used to separate treatment means where significant treatment differences were detected. 2.8. partial budget analysis partial budgets are useful and appropriate in the economic analysis of experimental data (byerle, 1980). partial budgets merely compare the changes in benefits with the changes in costs that are due to changes in treatments. the dominance analysis procedure as detailed in cimmyt (1988) was used to select potentially profitable treatments from the range that was tested. the selected and discarded treatments using this technique are referred to as undominated and dominated’ treatments, respectively. the cost-benefit ratio was calculated by considering the sale of prices of grain yield at harvesting time (8.0 etb/kg) and cost of fertilizers at sowing time (100kg nps/ 1500.0etb and 100kg urea/1450.0 etb) and their application costs per man-days (150.0 etb. the mean grain yield was adjusted by subtracting 10% to reflect the difference between experimental and farmer yields due to differences in management. then net benefit (nb) was calculated by subtracting the total variable cost from gross benefit (gb) and marginal rate of return (mrr%) was also calculated by the change in net benefit/change in total variable cost (tvc) x 100. thus, the treatment which was non-dominated and having a mrr of greater or equal to 50% with the highest net benefit was taken to be economically profitable. 3. results and discussion 3.1. effect of blended nps and n rates on growth parameters of maize varieties 3.1.1. leaf area index the main effects of nps fertilizer, year, variety significantly (p < 0.01) influenced leaf area index. however, the main effect of nitrogen fertilizer did not influence this variable of the plant. the two-factor interaction of year and variety also significantly (p < 0.05) influenced leaf area index. however, the three-factor interactions of variety × nps fertilizer × year as well as variety × n fertilizer × year also significantly (p < 0.05) influenced the leaf area index of the maize varieties (table 2). regarding the interaction effect of variety × nps fertilizer × year, among treatment relatively higher leaf area indices were recorded for baate variety in response to applying 50, 100, and 150 kg nps ha–1 in 2019. for example, for the year 2019, the leaf area index recorded for baate variety at the rate of application 50 kg nps ha–1 exceeded the leaf area index of melkassa 2 variety in the same year at the same rate of nps fertilizer application by about 36% (table 3). among treatments comparatively, the higher leaf area index of the baate variety and the lower leaf area indices of the melkasa-2 variety could be due to the existence of genetic variation between the two varieties. both varieties produced higher leaf area indices in the 2019 cropping season at all nps levels as compared to 2018. thus, in the year 2019, the leaf area index of the baate variety at the application of 50 kg nps per hectare exceeded the leaf area index of the same variety at the same rate of nps fertilizer application by about 88%. this is possibly due to the presence of optimum monthly rainfall distribution for maize production in the 2019 growing season (june to october) as compared to the 2018 growing season that may have led to favorable vegetative (leaf) growth as a result of improved photosynthesis. however, the higher leaf area index obtained in this study is lower as compared to the maximum optimum leaf area index (5 to 6) of maize described by tong et al. (2009). nevertheless, the lower the leaf area index could have, the greater the solar utilization efficiency, which is closely related to the grain number and weight during the filling stage. this result is in line with the findings of mekuannet belay and kiya adare (2020) who reported that leaf area index was significantly affected by variety, nps and year and produced a higher leaf area index (4.3) from the application of 150 kg nps ha–1 in 2019 as compared to 2018. similarly, rao et al. (2001) also reported that the application of optimum amounts of plant nutrients are important to promote the formation of chlorophyll which in turn resulted in higher photosynthetic activity, vigorous vegetative growth, and taller plants that produced more leaves per plant. similarly, sisay and adugnaw (2020) mekuannet and habtamu east african journal of sciences volume 15(2): 159-174 172 reported that the leaf area index of maize increased in response to increasing the rate of blended nps fertilizer. significant variations in leaf area indices were also observed due to the interaction of variety × n fertilizer × year. for instance, as n fertilizer increased from 43.5 to 130.5 kg ha–1, the leaf area index of the baate variety was slightly increased from 3.0 to 3.1 in the 2019 cropping season. the is because optimum application of n rate increases photosynthetic processes, the number of leaves per plant and leaf area as well as net assimilation rate (ahmad et al., 2009). similarly, tolera abera et al. (2017) reported that the leaf area index of maize was significantly affected by the interaction of variety by nitrogen but not affected by the application of different rate of n. mitiku woldesenbet and asnakech haileyesus (2016) also reported that the number of leaves per plant increased as nitrogen increased from 0 to 92 kg ha–1. on the other hand, the leaf area index of the melkasa-2 variety was increased by nearly 7.7% when the n fertilizer rate increased from 43.5 to 87 kg ha–1 in the same season (table 3). the lower harvest indices were recorded in the 2018 cropping season. this could be due to the availability of ill rainfall distribution in the 2018 cropping season resulted in lower leaf area indices in 2018. comparatively, the baate variety produced higher leaf area indices in both seasons. having small leaf areas and a small number of leaves per plant from the melkasa-2 variety may have resulted in lower leaf area indices. even though higher leaf indices (3.1) were found in some treatments, this value is lower as compared to the maximum optimum leaf area index obtained from hybrid varieties (tong et al., 2009). other findings also confirmed that the leaf area index was highly affected by variety and years (sun et al., 2019). leaf area index is also influenced by genotypes and environment as reported by birch et al. (1998). li et al. (2011) also reported that modern maize varieties had longer growth periods, higher leaf areas and slower leaf senescence. similarly, improved maize varieties had a higher leaf area index than local varieties lukeba (2013). from the aforementioned findings, it can be estimated that the optimum leaf area index for open-pollinated maize variety could be less than 5 or the optimum leaf area index of hybrid maize varieties. in the 2019 cropping season, higher leaf area indices were obtained at all fertilizer rates compared to in 2018 cropping season. this is possibly due to the presence of ample rainfall with even distribution throughout the growing season of 2019 that may attribute to have good root extension and development to absorb more soil nutrients for producing more leaves per plant. the result has coincided with mhizha et al. (2012) who reported that a significant increase of total seasonal precipitation is not important in rainfed maize production but its distribution is essential for crop phenology development. for instance, the minimum rainfall (18.8 mm) recorded in july may affect plant growth and development unlike that of 2019 which received 48.5 mm in the same month (figure 1). in addition, shorter plant heights were also recorded in 2018 cropping that may influence the number of leaves produced per plant. 3.1.2. plant height and ear height plant height was significantly (p < 0.05) influenced by the main effects of nps fertilizer, year, variety. however, it was not influenced by the main effect of nitrogen. this variable was significantly (p < 0.05) influenced also by the two-factor interaction of year and variety. however, it was also influenced by the three-factor interactions of variety × nps fertilizer × year as well as nps fertilizer × n fertilizer × year significantly (p < 0.01). ear height was influenced in the same way except that it was not influenced by the main effects of nps fertilizer (table 2). the tallest maize plants were recorded in the 2019 cropping year in response to the application of 50 kg nps ha–1 plus 43.5 kg n ha–1 and 50 kg nps ha–1 plus 87 kg n as well as in response to the application of 100 kg nps ha– 1 plus 43.5 kg n ha–1 and 100 kg nps ha–1 plus 130.5 kg n ha–1. in addition, the application of 150 kg nps ha–1 plus 43.5 kg n ha–1, 150 kg nps ha–1plus 87 kg n ha–1, 150 kg nps ha–1 plus 130.5 kg n ha–1 resulted in the tallest maize plants. on the other hand, the shortest maize plants were obtained in the 2018 growing year in response to all rates of the fertilizer application (table 4). for example, the average height of maize plants in the 2019 growing year obtained in response to the application of a higher rate of the nps fertilizer (100 kg nps ha–1) plus a higher rate of the nitrogen fertilizer (87 kg n ha–1) exceeded the average heights of maize plants in the 2018 growing season in response to the application of the lowest rate of the nps fertilizer (50 kg nps ha–1) plus the lowest rate of the nitrogen fertilizer (43.5 kg n ha–1) by about 59.2% (table 4). mekuannet and habtamu effects of blended nps and n rates on yield of maize 173 table 2. mean squares of pooled analyses of variances for growth parameters, yield components and yield of baate and melkasa-2 maize varieties during the 2018 and 2019 main cropping seasons in fedis district, eastern ethiopia. source of variation df lai ph (cm) eh (cm) neppl el(cm) ed(cm) nkpe tkw (g) by (t ha–1) gy (t ha–1) hi (%) replication (rep) 2 0.41 190.2 29.41 0.026 0.234 0.068 6307.0 1798.0 10.3 1.04 0.0008 year (y) 1 33.52* * 54742.5** 37352.5** 1.235** 112.44** 6.34** 57998.0** 147332.0** 1941.2** 271.3** 0.022** variety (v) 1 6.09** 585.7* 1017.5** 0.001ns 0.36ns 0.73** 109696.0** 47.0ns 62.7** 30.7** 0.0066* nps 2 0.31** 647.7* 141.1ns 0.125** 0.61ns 0.04ns 10416.0** 714.0ns 21.1* 7.4** 0.003ns nitrogen (n) 2 0.09ns 144.5ns 10.6ns 0.017ns 0.20ns 0.04ns 4109.0ns 106.0ns 5.2ns 2.8* 0.003ns v x nps 2 0.02ns 210.3ns 88.1ns 0.032ns 0.68ns 0.02ns 7588.0* 3498.0ns 10.9ns 3.3* 0.002ns v x n 2 0.06ns 123.9ns 44.5ns 0.047ns 0.63ns 0.07ns 1105.0ns 3549.0ns 7.0ns 0.01ns 0.009** v x y 1 0.72** 682.5* 223.9* 0.001ns 4.98* 0.03ns 1175.0ns 2851.0ns 16.2ns 1.5ns 0.003ns nps x n 4 0.72ns 272.4ns 63.7ns 0.054ns 1.83ns 0.03ns 1233.0ns 708.0ns 5.7ns 3.3* 0.002ns nps x y 2 0.01ns 143.1ns 22.8ns 0.003ns 1.27ns 0.04ns 9626.0** 1383.0ns 24.7** 2.4ns 0.001ns n x y 2 0.06ns 48.4ns 7.7ns 0.006ns 0.31ns 0.03ns 4125.0ns 695.0ns 1.9ns 1.2ns 0.001ns v x nps x n 4 0.08ns 448.1ns 39.6ns 0.030ns 0.80ns 0.05ns 1331.0ns 2644.0ns 17.4* 0.9ns 0.002ns v x nps x y 2 0.19* 1624.3** 273.6** 0.054ns 5.62** 0.10* 9969.0** 1167.0ns 48.5** 10.7** 0.001ns v x n x y 2 0.2* 379.6ns 10.9ns 0.090* 0.27ns 0.02ns 1160.0ns 1927.0ns 17.7* 1.6ns 0.0001ns nps x n x y 4 0.1ns 1561.7* 134.6* 0.054* 2.22ns 0.01ns 2129.0ns 1359.0ns 6.2ns 1.0ns 0.003ns v x nps x n x y 4 0.21ns 650.9ns 40.8ns 0.030ns 0.39ns 0.05ns 1813.0ns 1919.0ns 5.9ns 1.1ns 0.001ns error 70 0.06 9499.7 46.01 0.021 1.07 0.026 1757.0 1934.0 4.93 0.76 0.001 cv (%) 11.2 448.1 11.2 14.0 6.6 3.6 8.7 13.3 17.2 16.5 8.7 note: ns,* and **; non-significant; significant at p < 0.05 and p < 0.01, respectively; df = degree of freedom; lai = leaf area index; ph = plant height; eh = ear height; neppl = number of ears per plant; el = ear length; ed = ear diameter; nkpe = number of kernels per ear; tkw = thousand kernels weight; by= biomass yield; gy= grain yield; hi = harvest index; and cv = coefficient of variation. mekuannet and habtamu east african journal of sciences volume 15(2) 159-174 174 table 3. leaf area index of maize as influenced by the interactions of variety × nps × year as well as variety × n fertilizer × year during the 2018 and 2019 main cropping seasons in fedis district, eastern ethiopia. treatment nps fertilizer rate (kg ha–1) variety year 50 100 150 baate 2018 1.6d 1.9c 1.9c 2019 3.0a 3.1a 3.1a melkasa-2 2018 1.4d 1.5d 1.5d 2019 2.2c 2.5b 2.5b lsd (0.05) 0.23 nitrogen fertilizer rate (kg ha–1) baate 43.5 87 130.5 2018 1.8ef 1.9de 1.6fg 2019 3.0a 3.1a 3.1a melkasa-2 2018 1.4h 1.5gh 1.5gh 2019 2.6b 2.4bc 2.3cd lsd (0.05) 0.23 cv (%) 11.2 note: means in the table following the same letters are not statistically significant at 0.05probability level; lsd = least significant difference; and cv = coefficient of variation. an adequate application of blended fertilizer to maize plant under adequate rainfall may enable the plant to take up more water and nutrients from the soil. this could be attributed to more photosynthesis and translocation of assimilates to vegetative parts rather than reproductive parts, as a result of which the tallest plants were recorded at the highest fertilizer rate. similarly, ullah et al. (2015) reported that nitrogen is an essential element that increases plant height because it facilitates active cell division to form building blocks for cell expansion. nitrogen is also essential for utilization of carbohydrates within plants and stimulation of root development as well as uptake of other nutrients (khan et al., 2014). the result is in line with the findings of mitiku woldesenbet and asnakech haileyesus (2016) who reported that plant height was increased as nitrogen rate was increased from 0 to 92 kg n ha–1. similarly, alias et al. (2003) stated that the maximum plant height (195.9 cm) was obtained in response to applying 125 kg p ha–1. berhe meresa and marie belay (2020) also reported that the application of blended fertilizer significantly increased plant height as compared to the control treatment and other treatments that received lower rates of the fertilizer. application of the blended fertilizer significantly increased plant height as compared to the recommended np fertilizers and the control treatment (dagne chimdessa, 2016). maqsood et al. (2001) and ayub et al. (2002) also reported that a significant effect of np application was observed on plant height in response to increasing the application of np fertilizer. the tallest maize ears were recorded in the 2019 growing year in response to the combined application of 50 kg nps fertilizer ha–1 with 43.5 and 87 kg n fertilizer ha–1. similarly, the combined application of 100 kg nps ha–1 with 87, and 130.5 kg n ha–1, as well as 150 kg nps fertilizer ha–1 with all the nitrogen fertilizer rates, as well as 150 kg nps fertilizer ha–1 with all the nitrogen fertilizer rates produced the highest ear heights in the same growing year. the combined application of 100 kg nps fertilizer with 87 kg n fertilizer in the 2019 cropping year increased the ear height of the maize plant nearly by 56% over the lowest combined fertilizer application of 50 kg nps plus 43.5 kg n in the 2018 cropping year. the shortest ear height recorded at the lowest combined fertilizer application rate could be due to poor root development, extension and stunted growth of maize plant owing to deficiency of phosphorus and nitrogen fertilizers. this result is harmonized with the findings of kidist abera (2013) who reported that the ear height of maize increased from 138.3 cm to 163.3 cm as the n rate increasing from 0 to 174 kg n ha–1. similarly, findings also reported by geremew taye (2009). mekuannet and habtamu effects of blended nps and n rates on yield of maize 175 table 4. plant height, ear height and number of ears per plant as influenced by interaction effect of nps × n × year during the 2018 and 2019 main cropping seasons in fedis district, eastern ethiopia. year nps rate (kg ha–1) n rate (kg ha–1) plant height (cm) ear height (cm) number of ears per plant 2018 50 43.5 113.2g 37.0f 0.86h 87 122.2e–g 40.0ef 0.89gh 130.5 119.0fg 40.3d–f 0.91f–h 100 43.5 124.3d–g 44.5de 0.88gh 87 118.8fg 39.2ef 0.92f–h 130.5 131.8de 44.5de 0.99e–h 150 43.5 127.0d–f 41.7d–f 0.96e–h 87 135.8d 47.3d 1.03d–g 130.5 128.8d–f 43.2d–f 0.97e–h 2019 50 43.5 173.3ab 81.6a 1.062c–f 87 169.8a–c 78.4a–c 1.23ab 130.5 158.4c 74.1bc 0.95e–h 100 43.5 161.3bc 73.7c 1.063b–f 87 180.2a 84.0a 1.22a–c 130.5 168.1a–c 78.8a–c 1.18a–d 150 43.5 169.5a–c 80.8ab 1.26a 87 169.3a–c 78.8a–c 1.11a–e 130.5 176.2ab 83.2a 1.27a lsd (0.05) 13.4 7.8 0.17 cv (%) 7.9 11.2 14.0 note: means in the table following the same letters are not statistically significant at 0.05 probability level; lsd= least signific ant difference; and cv = coefficient of variation. 3.2. effect of blended nps and n rates on yield components and yield of maize varieties 3.2.1. number of ear per plant the number of ears per plant was significantly (p < 0.01) influenced by the main effects of nps fertilizer and year. however, it was not significantly affected by the main effects of variety and nitrogen fertilizer. on the other hand, the number of ears per plant was significantly (p < 0.05) influenced by the three-factor interactions of variety × n fertilizer × year as well as nps fertilizer × nitrogen fertilizer and year (table 2). the maximum numbers of ears per plant within treatments were recorded from plants supplied with combined application of 100 kg nps fertilizer ha–1 with 87 and 130.5 kg n fertilizer ha–1 as well as 150 kg nps fertilizer ha–1 with all rates of the nitrogen fertilizer in 2019 growing year (table 4). this result indicated that the application of 150 kg nps fertilizer ha–1 plus 130.5 kg n fertilizer ha–1 under ample and good monthly rainfall distribution could be an optimum fertilizer rate to produce more photosynthetic activity and synthesized more carbohydrate that stimulated root growth and development of economic parts resulted in a higher number of ears per plant. similarly, dagne chimdessa (2016) reported that the number of ears per plant increased as the blended fertilizer rate increased. on the other hand, kumar and kumar (2017) stated that the application of 100 kg p ha–1gave the maximum number of ears per plant (1.25). the minimum number of ears per plant of maize was obtained from the lowest combined fertilizer application rate (50 kg nps ha–1 and 43.5 kg n ha–1) in the 2018 growing year. the minimum numbers of ears per plant were recorded in the 2018 growing year compared to the 2019 growing year. this is probably because the presence of adequate rainfall with good monthly distribution in the 2019 growing year may help soil nutrients become easily available to plant roots. similarly, jifara gudeta et al. (2021) reported that increasing npszn level from 0 to 100 kg ha–1 and n level from 0 to 35.4 kg ha–1 significantly increased the number of cobs per plant from 1.00 to 2.00. 3.2.2. ear length and diameter the ear length of maize was significantly (p < 0.01) influenced by the main effect of year but other main effects were non-significant. besides, it was also significantly (p < 0.05) affected by the three-factor interaction of variety × nps fertilizer × year. ear diameter was affected in the same way except that it was significantly (p < 0.01) affected by the main effect of variety (table 2). the longest ear lengths of maize were produced from the baate variety fertilized with all nps fertilizer rates in the 2019 growing year, but these mean values of ear lengths were statistically at par with the mekuannet and habtamu east african journal of sciences volume 15(2): 159-174 176 melkasa-2 variety received the same nps fertilizer rates in the same growing year (table 5). this is probably baate variety could be better to convert growth resources into economic part or provide assimilates to sink. the maximum assimilates supply should be available during maize grain filling (arif et al., 2010). the probable reason could be due to a favorable environment optimum utilization of solar light, higher assimilated production and its conversion to starches resulted in higher ear length as reported by derbay et al. (2004). similarly, jifara gudeta et al. (2021) reported that the highest ear length of maize (18.0 cm) was obtained from the blended application of 100 kg npszn and 35.4 kg n ha–1. however, shorter ear lengths of maize were recorded for both varieties in the 2018 growing year almost in all nps fertilizer rates as compared to the 2019 growing year. the mean values of ear lengths obtained from the baate variety were slightly higher than those obtained from melkasa -2 variety in the 2019 growing year. the ear length of the baate variety grown in 2019 growing at 50 kg and 100 kg nps fertilizer ha–1 exceeded the ear length of the same variety grown in the 2018 year at the lowest nps fertilizer application rate of 50 kg ha– 1 by 25.7%. the highest ear diameters of the baate variety were produced in response to applying 100 kg nps and 150 kg nps fertilizer ha–1 in the 2019 growing year. the ear diameters of baate and melkasa-2 were increased from 4.63 to 4.85 cm and 4.55 to 4.65 cm in the same order in the 2019 growing ear. similarly, the same trends were also observed in the 2018 growing year albeit thinner ear diameters were recorded compared to the ear diameters recorded in the 2019 growing year. the average ear diameters of baate variety obtained in response to the application of the highest nps fertilizer rate (150 kg nps ha–1) in 2019 growing year increased the average ear diameter of melkasa-2 variety obtained in response to the application of the lowest nps fertilizer rate (50 kg nps ha–1) in 2018 growing year nearly by 19.5%. this is possibly due to adequate fertilizer application to the maize plants under good rainfall amount and distribution, which may have resulted in vigorous growth that helps to produce more green leaves to produce more photosynthetic assimilates and translocate to the sink (kernels) resulted in large size. perhaps kernel size may be one of the determinant factors for ear diameter due to varietal difference. similarly, onasanya et al. (2009) found that the highest ear diameter was obtained at the higher phosphorus fertilizer application. table 5. ear length and ear diameter of maize varieties as influenced by the interaction of variety, nps and year during the 2018 and 2019 main cropping seasons in fedis district, eastern ethiopia. variety nps (kg ha–1) ear length (cm) ear diameter (cm) 2018 2019 2018 2019 baate 50 13.6d 17.1a 4.21de 4.63bc 100 14.4cd 17.1a 4.33d 4.75ab 150 15.0c 16.3ab 4.33d 4.85a melkasa-2 50 15.3bc 16.2ab 4.06f 4.55c 100 14.8c 16.8a 4.07ef 4.63bc 150 14.5cd 16.5a 4.15ef 4.65bc lsd (0.05) 0.97 6.6 0.15 3.6 cv (%) note: means in the table following the same letters are not statistically significant at 0.05 probability level; lsd = least significant difference; and cv = coefficient of variation. 3.2.3. thousand kernels weight and number of kernels per ear thousand kernel weight was significantly (p < 0.01) influenced by the main effect of year but other main effects were non-significant. the number of kernels per ear was significantly (p < 0.01) affected by the main effects of year, variety and nps fertilizer. however, the main effect of nitrogen did not show a significant effect on this yield component. on the other hand, this yield component was also significantly (p < 0.05; p < 0.01) affected by the two-factor interactions of variety × nps fertilizer as well as nps fertilizer × year, respectively. in addition, it was also significantly (p < 0.01) influenced by the three-factor interaction of variety × nps fertilizer × year (table 2). the mean thousand kernel weight obtained in the 2019 growing year increased by 25.2% over the mean thousand kernel weight obtained in the 2018 growing year. this could be due to the presence of good monthly rainfall distribution throughout the cropping season that may extend the grain-filling period. the maximum numbers of kernels per ear of the baate variety were attained when the plants were fertilized with 50 kg nps and 100 kg nps ha–1 in the 2019 growing year. for each growing year, the average numbers of kernels per ear obtained from both varieties increased with the increasing nps fertilizer from 50 to 150 kg nps mekuannet and habtamu effects of blended nps and n rates on yield of maize 177 ha–1except baate variety in the 2019 growing year (table 7). for instance, the average number of kernels per ear obtained from melkasa-2 increasing by 11.8% and 9.0% as the nps fertilizer rate was increased from 50 to 150 kg ha–1 in 2018 and 2019 growing years, respectively. the average number of kernels per ear obtained for baate variety in response to the application of the higher nps fertilizer rate (100 kg nps ha–1) in 2019 growing year surpassed the average of the number of kernels per ear obtained for melkasa-2 variety in response of the application of the lowest nps fertilizer rate (50 kg nps ha–1) in 2018 growing year closely by 34.8%. this could be because the longest ears and widest ear diameters were found for baate maize variety in response to applying 100 kg nps fertilizer rate in 2019 cropping season, which could have a direct contribution to producing the maximum number of kernels per ear. this may be due to maximum photosynthetic activity and carbohydrates use within a plant that stimulated root growth and development as well as the uptake of other nutrients (khan et al., 2014). similarly, alias et al. (2003) reported that increasing the rate of phosphorus from 0 to 125 kg ha–1 increased the number of kernels per ear of maize. maqsood et al. (2001) also found that number of kernels per ear of maize was increased as p and n increased to a certain level. reported that the number of kernels per was significantly affected by np and variety (khan et al., 2014). 3.2.4. aboveground biomass yield aboveground biomass yield was significantly (p < 0.01; p < 0.05) affected by the main effects of variety, year and nps fertilizer, respectively. this yield was also significantly (p < 0.01) affected by the two-factor interaction of nps fertilizer and year. moreover, it was significantly (p < 0.05) influenced by the three-factor interactions of variety × nps fertilizer × year as well as variety × n fertilizer × year and significantly (p < 0.01) affected by similar interaction of variety × nps fertilizer × n fertilizer (table 2). the highest aboveground biomass yield of the baate variety was obtained in response to the application of the highest combined fertilizer rate of 150 kg nps fertilizer ha–1 plus 130.5 kg n fertilizer ha–1. the aboveground biomass yield of the baate variety increased as the nps fertilizer rate was increased from 50 to 150 kg ha–1 at each rate of the nitrogen fertilizer. however, the same trends were not observed for melkasa-2 variety (table 6). the average aboveground biomass yield obtained from melkasa-2 variety in response to the application of 50 kg nps fertilizer ha–1 plus 130.5 kg n fertilizer reduced from the average aboveground biomass yield obtained from baate variety in response to the application of the highest combination fertilizer rate (150 kg nps ha–1 and 130.5 kg n ha–1) by 83.2%. indeed, the baate variety produced higher aboveground biomass yields at all fertilizer levels as compared to the melkasa2 variety. because higher mean values of growth variables and yield components of baate variety were recorded in the 2019 growing year, which could be attributed to the higher biomass yield produced in the same year. this is possibly due to the presence of genetic variation along with good monthly rainfall distribution. in this case, the baate variety had a better response to applied fertilizer rates for producing higher biomass yield. similarly, mekuannet belay and kiya adare (2020) reported that the responses of varieties to applied nutrients are governed by soil moisture. consistent with the results of this studyy, ahmad et al. (2018) also reported that variety and nitrogen had a significant effect on biomass yield of maize similarly, geremew taye et al. (2015) and hussain et al. (2015) and reported that biological yield of maize was influenced by the combined application of p and n. table 6. aboveground biomass yield of maize varieties as influenced by the interaction of variety x nps x n during the 2018 and 2019 main cropping seasons in fedis district, eastern ethiopia. note: means in the table following the same letters are not statistically significant at 0.05 probability level; lsd = least significant difference; and cv = coefficient of variation. variety nps (kg ha–1) n (kg ha–1) 43.5 87 130.5 baate 50 13.67b–e 13.7b–d 13.3c–f 100 13.8b–d 14.9bc 13.7b–d 150 14.0b–d 15.8b 18.5a melkasa-2 50 11.7d–h 10.76gh 10.1h 100 10.4h 10.8f–h 13.2c–g 150 12.5c–h 10.7h 11.2e–h lsd (0.05) = 2.56 cv (%) = 16.7 mekuannet and habtamu east african journal of sciences volume 15(2): 159-174 178 3.2.5. grain yield the main effects of all three factors, namely, nps fertilizer, n fertilizer, year, and variety significantly (p < 0.05) influenced the grain yield of maize. in addition, the two-factor interactions of nps fertilizer and variety as well as that of nps and n fertilizer significantly (p < 0.05) influenced this variable of the plant. however, the higher order interaction, namely, the three-factor interaction of variety × nps fertilizer × year also significantly (p < 0.01) affected the grain yield of the crop (table 2). for each growing year, increasing the rate of the nps fertilizer increased the grain yield of the crop. however, significantly higher grain yields were obtained in the 2019 growing season for both varieties. thus, the highest grain yields were obtained for the baate variety in the 2019 growing in response to the application of 100 kg nps ha–1 as well as 150 kg nps ha–1. however, the lowest grain yield for this variety in the same year was obtained in response to the application of 50 kg nps ha–1. however, the yield increments in the year 2019 were only slight, although significant, and amounted to only 13% when comparing the application of 50 kg nps ha–1 and 150 kg nps ha–1. however, the grain yield of the baate variety obtained in the 2019 cropping year in response to the application of 150 kg nps ha–1 exceeded the grain yield of the same variety obtained in 2018 in response to the application of 50 kg nps ha–1 by about 196%. the response of varieties to applied fertilizer could be due to the low contents of total nitrogen and available phosphorus as indicated in soil analysis in table 1. melkasa-2 maize variety produced the lowest grain yields in the year 2018 in response to the application of all three rates of the nps fertilizer (table 7). for each growing year, the average grain yields of both varieties increased as nps fertilizer was increased from 50 to 150 kg ha–1although the extents of increment at all nps fertilizer rates varied between the two growing years. this probably signifies that the application of adequate amounts of fertilizer to maize plants in the presence of an adequate amount and evenly distributed rainfall like in the 2019 growing season (figure 1) promotes higher availability of nutrients of the nutrients and their uptake by plants. similarly, mugiyo et al. (2018) reported that the higher amount of rainfall and even distribution of rainfall produced a higher grain yield of maize. therefore, the maximum grain yield at the highest level of p may be due to adequate availability of nutrients in the soil and their uptake by the plants especially during the seed filling stage improved production and partitioning of photoassimilates to reproductive part especially during the time of seed formation. possibly, the existence of a varietal difference between the two varieties may have had its contribution to yield variations. this result is in line with the findings of tolera abera et al. (2009) who reported that the grain yields of maize varieties were significant across the cropping seasons, and higher grain yields of maize were obtained in the 2001 cropping season as compared to 2003. similarly, mekuannet belay and kiya adare (2020) also reported that that the highest grain yield of maize was obtained from the combined application of 150 kg nps ha–1 with 130.5 kg n ha–1 in the 2019 cropping season. kumar and kumar (2017) also confirmed that the highest grain yield of maize (6.0 t ha–1) was found for plots fertilized with 100 kg ha–1 p as compared to lower p levels. higher grain yields of two maize varieties were recorded in 2019 as compared to the 2018 main cropping season though the baate maize variety produced much higher grain yields than the other variety at almost all fertilizer rates in both seasons. almost all yield components namely, number of ears per plant, ear length, ear diameter, number of kernels per, thousand kernel weight, and biomass obtained in the 2018 growing year were lower as compared to 2019. as a result, the average grain yields of both varieties obtained in this season were low. because these yield components could have a direct contribution to the grain yield. the reduction in yield components in the 2018 growing year could be due to erratic rainfall distribution (figure1). mhizha et al. (2014) reported that maize requires about 600 mm of rainfall of even distribution to reach physiological maturity. other findings ahmad et al. (2018) also confirmed that maize crop can be grown where annual precipitation exceeds 600 mm with well distributed over the growth period. annual total rainfall received in the 2018 cropping season was higher in that of 2019 cropping season but its distribution was not regular as 2019. therefore, this confirmed that the rainfall distribution (rain days) is more important than seasonal totals and strongly correlated to district maize average yield as described by mugiyo et al. (2018). similarly, zerihun abebe and hailu feyisa (2017) reported that the average grain yield of maize varied due to seasons. significantly, a higher average grain yield of maize was obtained from the highest application of n fertilizer rate. thus, the average grain yield obtained in response to the application of the highest rate of n fertilizer (130.5 kg n ha–1) exceeded the average grain yield obtained from the application of the lowest n fertilizer rate (43.5 kg n ha– 1) by about 12.2%. similarly, zerihun abebe and hailu feyisa (2017) reported that the highest average grain yield of maize was found from the application of a higher n fertilizer rate (92 kg ha–1). the findings of geremew taye et al. (2015) also confirmed that grain yield of maize increased as the nitrogen application rate was increased from 0 to 184 kg ha–1. this apparently signifies that response of maize to the applied n fertilizer may be due to low contents of total nitrogen in the soil (table 1). mekuannet and habtamu effects of blended nps and n rates on yield of maize 179 table 7. number of kernels per ear and grain yield of maize varieties as affected by the interaction of variety by nps and year in 2018 and 2019 main cropping seasons in fedis district, eastern ethiopia. variety number of kernels per ear grain yield (t ha–1) nps (kg ha–1) 2018 2019 2018 2019 baate 50 430.1fg 550.8ab 2.7g 7.1bc 100 521.5a–c 555.8a 4.0e 7.7ab 150 507.8b–d 511.6bc 5.5d 8.0a melkasa-2 50 412.2g 447.9fg 3.2e–g 5.5d 100 414.9g 471.1b–f 3.7ef 6.3cd 150 460.9ef 488.3c–e 3.1fg 6.7c lsd (0.05) 39.41 0.82 16.5 cv (%) 8.7 note: means in the table following the same letters are not statistically significant at 0.05 probability level; lsd = least significant difference; and cv = coefficient of variation. 3.3. partial budget analysis this partial budget analysis was done based on the average yield of each treatment across all repetitions (duncan et al., 1990) to assess only significant treatments to select the most economically feasible rates of nps treatments on two pollinated maize varieties. partial budget analysis was done for only significant treatments by taking the mean grain yield of two seasons. based on partial budget analysis, the highest net benefit (44,850.0 etb) with the highest marginal rate of return (764 %) was obtained from baate variety at 150 kg nps ha– 1application rate in the 2019 cropping season. similarly, the application of 100 kg nps ha–1produced the highest net benefit (39,120.0etb) with a higher marginal rate of return (812%) in the same season. this is probably due to the presence of a regular monthly distribution of rainfall throughout the growing season in 2019. the application of 87 kg n to both varieties gave the highest net benefit (33240.82 etb) with a marginal rate of return (85%) which is economically feasible. 4. conclusions the results of this study have demonstrated that the application of 150 kg nps fertilizer ha–1to baate variety produced the highest grain yield. the highest net benefit (44, 850.0 etb) with the highest marginal rate of return (764 %) was obtained for the baate variety at 150 kg nps ha–1 application rate in the 2019 cropping season. in addition, the application of 87 kg n to both varieties produced the highest net benefit (33, 240.82 etb) with a marginal rate of return (85%) which is economically feasible. therefore, it is concluded that applying 150 kg nps fertilizer ha–1as well as 87 kg n fertilizer ha–1 to baate variety is the optimum fertilizer rate to get economical grain yield in the study area and other similar agroecology in both years. the results imply that the productivity of maize is determined by the availability of sufficient n, p, s in the soil supplied as fertilizer in the study area. the results also indicate that the availability of sufficient moisture in the soil during the growing period is also a vital prerequisite for enhanced production of the crop. thus, the baate maize variety is the best for producing the crop in the study area with the aforementioned rates of the fertilizers. farmers in the study area should, therefore, be advised to use this variety and the aforementioned fertilizer rates to produce the crop. further research should be conducted to investigate effects of mineral fertilizers integrated with organic fertilizers as well as irrigation water on maize productivity across various locations and growing years. 5. acknowledgements the authors thank haramaya university for financing the research, and several technical assistants who provided support during field management and data collection. 6. references ahmad, s., ahmad, r., ashraf, m.y., ashraf, m. and waraich, e.a. 2009. sunflower 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and hailu feyisa. 2017. effects of nitrogen rates and time of application on yield of maize: rainfall variability influenced time of n application. international journal of agronomy, 2017:1–11. https://www.researchgate.net/publication/272498751 https://www.researchgate.net/publication/272498751 east african journal of sciences (2018) volume 12 (1) 77-82 _____________________________________________________________ licensed under a creative commons *corresponding author. e-mail: wasmoha@yahoo.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) registration of a new “improved huruta” shallot variety with true seed production potential wassu mohammed*, kebede woldetsadik, and bekele kebede 1school of plant sciences, haramaya university, p. o. box 138, dire dawa, ethiopia abstract: shallot (allium cepa var. ascalonicum backer) is an important vegetable crop cultivated by smallholder farmers for consumption and income generation in ethiopia. however, scarcity of high yielding varieties as well as lack of superior planting material seriously constrains productivity of the crop. the crop has degenerate seed production potential and it is usually established using bulbs. the perishability of the fleshy planting material and its sheer bulkiness and predisposition to fungal and viral disease creates difficulties in handling the material. what is more, large quantities of bulbs are required to plant a relatively small area of land, which exacerbates the problem of shortage of planting material. also it is the edible part of the plant that is used for planting, which compromises the potential for consumption and marketing. therefore, a research project was initiated aiming at producing true seeds from the non-seed producing huruta variety. a series of experiments were conducted using the randomized complete block design to identify the appropriate planting date and plant growth hormone application (gibberellin acid, ga3) for bolting and seed production. as a result, the original non-seed producing huruta variety was essentially improved for production of true seeds and bulb through seed-to bulb to seed selection method. thus, a shallot (allium cepa var. ascalonicum backer) variety with the original name huruta (dz-sht-91) was tested. the variety was evaluated for production of bulbs and true seeds over several years (2010 to 2017) at 12 different locations as well as on fields of 28 farmers along with three onion varieties, namely, adama red, bombay red and kelafo hybrid as well as three shallot (huruta produced from bulb, atilase and dz-94) varieties. the performance of the shallot variety was evaluated against commercial onion varieties propagated by true seeds to verify its stability and superiority for bulb and seed productions. the shallot variety was more stable over locations and years. it had an average true seed yield advantage of about 321% over the three onion and shallot varieties. it had also average marketable bulb yield and marketable bulb weight advantages of 35 and 31%, respectively, over the three onion varieties. therefore, this variety was selected, verified, and declared as improved huruta shallot variety with potential of producing true seed. owing to its advantage over the tested commercial onion varieties for production of true seeds and bulb as well as many other superior bulb quality traits, this variety was approved for cultivation at mid and high altitude areas of eastern ethiopia and similar agroecologies of the country. therefore, the release of this new shallot variety will contribute to enhanced production of the crop not only owing to its high bulb yield but also because it affords farmers the opportunity to effectively and efficiently propagate the crop using true seed. enhanced production of the cop will also lead to improved farmers’ income and livelihoods. keywords: allium cepa var. ascalonicum backer; improved huruta shallot variety; marketable bulb yield; stability; true seed. 1. introduction shallot and onion belong to the genus allium. shallot is formerly known as allium ascalonicum l., a separate species from onion (george, 1999), but later it was identified that shallots are allium cepa var. ascalonicum backer as the most important subgroup of the aggregatum group and the only one grown commercially (rabinowitch, 1990). shallots are known as vegetatively propagated varieties of allium cepa. true seed production potential of shallot was tested in many countries of the world but the success history was not as good as that of onion and other crops. the vegetative propagation of shallot requires a large quantity of planting material as bulb (1.2 t ha-1 bulbs) (jackson et al., 1985) that can be used for consumption, which is expensive, bulky to transport and needs well ventilated storage. bulbs keep for short periods of time and carry fungal diseases (mengistu and seid, 1990) and latent viruses (proctor, 1987) from generation to generation. in contrast, the use of true seeds has an advantage of ease of propagation and solves the disease problems transmitted through bulbs as planting material. the use of true seed also increases the sizes of bulbs and enables genetic improvement through natural outcrossing and/or planned crossing programs. however, bolting does not occur readily and easily in mailto:wasmoha@yahoo.com wassu et al. east african journal of sciences volume 12 (1) 77-82 78 many shallot varieties (currah and proctor, 1990). therefore, production of true seeds from shallot requires great efforts to regulate flowering (van nocker, 2001) through application of plant growth hormones or identifying favourable season(s) for the flowering of the crop. in ethiopia, shallot is one of the most widely cultivated bulb crops under rain-fed conditions by smallholder farmers as an income generating spice crop. the crop has a wide range of adaptation to climatic and soil and is cultivated both under rain-fed and irrigated conditions (kebede, 2003). shallot is mostly produced at highland areas under rain-fed conditions (shimeles, 2014), but the cultivation and distribution of the crop is being expanded to new areas (lemma and shimeles, 2003). the national average bulb yield of shallot is about 7 t ha-1 (shimeles, 2014) and it is substituted by recently introduced onion due to ease of propagation from true seeds. many factors such as diseases, insects and lack of improved pre and post-harvest management practices contribute to low yield and quality (getachew and asfaw, 2004). the main constraint to shallot production in the country is the need of using 1.5 2 t ha-1 of edible bulbs as planting material which comprise about 40% of the total cost of production compared to 4–5 kg ha-1 of true seed (lemma and yayeh, 1994). therefore, the production of true seeds from shallot has multiple advantages. realizing this fact, haramaya university initiated true seed production from huruta shallot variety which was released in 1997/98 (moanr, 2016) and entirely propagated by bulbs. the seed production from huruta shallot variety was started during 2004/2005 and the subsequent improvement of the variety was continued for 12 years. a series of experiments were conducted in which the first phase was focused on seed production using plant growth hormone (ga3) and identifying appropriate locations and seasons for flowering and seeding. the second phase was evaluation of the bulb yield of the variety produced from true seeds and bulbs. as the third phase, the seed yield of huruta was evaluated in comparison to other seed producing shallot varieties and onion variety over locations. the fourth phase was devoted to bulb yield evaluation of the variety from true seeds over locations and seasons in comparison to commercial onion varieties and at final the verification of the variety for yield was conducted in 2016. after a series of efforts, the original non-seed producing huruta shallot variety was essentially improved for enhanced true seed and bulb production better than the seed production potential of commercial onion varieties through seed-to-bulb seed selection method and approved for cultivation. 2. agronomic and morphological characteristics the released variety was given the local name improved huruta shallot variety. the variety has nine leaves, 58.7 and 47.4 cm of plant height and leaf length, respectively. it produces a bulb with a deep red color with smaller proportions of unmarketable bulbs. it has large-sized bulbs with an advantage of 31.40% marketable bulb weight increase over the commercial onion varieties. the improved huruta shallot variety has been essentially improved for enhanced seed yield better than onion and shallot varieties with 95% average bolting. it has an average true seed yield advantage of 321.43% over three onion and shallot varieties. this will simplify production of reasonably high seed yield from the variety and enable researchers to improve the variety further through planned hybridization programs or through selection from populations created by natural outcrossing. seedlings are grown in a nursery and transplanted 45-50 days after sowing. the variety requires 120 days for bulb and seed maturity after transplanting of seedlings and planting bulbs, respectively. therefore, 8 and 10/11 months were sufficient to produce true seeds from bulb-to-seed and seed-to-bulb-to-seed methods, respectively. the detailed description of improved huruta shallot variety is presented in table 1. 3. bulb and true seed yields the improved huruta shallot variety was evaluated for production of true seed in 2014 at five locations in parallel with one onion and two shallot varieties. the variety was evaluated for bulb yield for two seasons (2014/15 and 2015/16) at three locations along with three onion varieties. in addition, in 2015/16, the variety was evaluated for bulb yield at two locations on 28 farmers’ fields under farmers’ management practices. on average, the improved huruta shallot variety produced marketable bulbs with the mean weight 72 g with overall bulb yield advantages of 18.29% over three onion varieties. it produced 36.74 and 45.14 t ha-1 of marketable and total bulb yields with the overall advantages of 35.03 and 22.37% over the three commercial onion varieties, respectively. the improved variety produced a mean true seed yield of 5.72 g per plant and 953.4 kg ha-1 with an overall mean true seed yield advantage of 321.43% over the three check onion varieties. the seeds of the variety exhibit no dormancy and could be stored for two years with 98% average germination capacity four days after sowing the seed. wassu et al. improved huruta shallot variety 79 table 1. agronomic characters of improved huruta shallot variety. characteristics “improved huruta” shallot variety adaptation area and management medium to high altitudes of eastern ethiopia (1600-2800 meters above sea level) rainfall (mm) 760-1010 planting season for bulb production all year round both under rain-fed and irrigation planting date for seed production during the rainy season (early august) under haramaya conditions seeding rate (kg ha-1) 2 to 3 at 15 and 40 cm between plants and rows/ridges (166667 plants/ha) spacing (cm) 40 x 20 x 10 (double rows) fertilizer rate (kg ha-1) 46 kg p2o5 or 100 kg dap and 64 kg n or 100 kg urea + 18% n from 100 kg dap fertilizer application time all dap at planting but half n rate at planting and half at active growth stage fertilizer application method drilling in row weeding weed free seed beds and farms throughout the plant life disease and insect control application of ridomil and mancozeb for downy mildew and purple blotch and karate for thrips as per manufacturers recommended rates seedling transplanting after sowing (days) 45-50 harvesting and storage average bulb maturity for harvest (days) 120 average maturity for seed production (days) 120 average bulb to seed production (months) 8 seed to bulb to seed production (months) 10 to 11 bulbs for storage bulbs for storage harvested when 50% or more of the tops have broken over curing bulbs for storage cured and dried under shade thoroughly for one week before being placed in storage bulbs for immediate use bulbs undercut when 15 to 25 percent of the tops are down tops and roots cut tops and roots of bulbs removed during harvest morphology plant height (cm) 58.7 leaf length (cm) 47.4 number of leaves 9 bulb yield and bulb character bulb color deep red marketable bulb weight (g) 72 proportion of unmarketable bulbs (%) 18 marketable bulb yield (t ha-1) 36.74 total bulb yield (t ha-1) 45.14 bulb dry matter content (%) 13.5 total soluble solid (tss) obrix 14 average bulb storage period under ambient temperature (22 to 25oc or at haramaya condition) (month) 2 seed production bolting (%) 95 seed yield (g/plant) 5.72 seed yield (kg/ha) 953.4 1000 seed weight (g) 3.4 pure seed (%) 97 seed germination (%) 98 average seed germination period (days) 4 seed dormancy no seed dormancy average bulb sprouting period at haramaya condition (month) 2 1/2 sorting of mother bulbs bulbs checked when lifted for color, size and morphology to true to wassu et al. east african journal of sciences volume 12 (1) 77-82 80 type, discard bloting, bull-necked, bottle shaped, split doubles, damaged or diseased bulbs bulb size medium-sized shallot bulbs are harvested, stored for some time in well ventilated storage houses and then replanted mother bulbs growing and amount mother bulbs grown in the same way as the crop for market and 1200 to 1500 kg bulbs/ha required isolation distances about 1 to 2 km distance between other onion cultivars and other seed producing shallot cultivars seed producing area mid to high altitude (1600 to 2800 m.a.s.l.), coincide in month of low humidity & mild cool temperature during initial growth by increase in temperature at later stages of the crop and clear and bright days at flowering seed heads/umbel harvest successive seed heads cut 10-15 cm of stem attached when heads turned to silver and seeds are dark black color seed extraction seed heads dried outdoor under sun, threshed after completely dried, seeds separated from their capsules by rubbing in the hand and seeds are collected after cleaning seed moisture the seeds dried after extraction and cleaning to 12% moisture content or lower seed storage for more than 2 years under cool dry condition release year 2017 breeder/maintainer haramaya university 4. bulb and seed yield stability the stability of the improved huruta shallot variety for bulb weight as well as bulb and true seed yields was tested along with three onion and two shallot varieties as checks. a regression data analysis method was employed, because this method is useful to explain a large part of the variation in total yield (pompiliu et al., 2009). the largest proportions of 95.57 and 96.71% variations for marketable bulb yield (figure 1) and marketable bulb weight (figure 2), respectively, were due the responses of the improved variety to the environments. strong and significant correlations were observed between mean values of environments and the improved variety both for marketable bulb weight (r = 0.984) and marketable bulb yield (r = 0.978). as it could be visually observed from the scattered plot (figure 1 and figure 2), the improved variety was more stable and better in performance than the three commercial onion varieties both under favorable and unfavorable environments for marketable bulb yield and marketable bulb weight. the improved huruta shallot variety produced lower total bulb and true seed yields than kelafo onion hybrid (figure 3) and the three onion varieties (figure 4) ), respectively, under unfavorable environments. however, the differences under unfavorable environments were very low and more importantly the improved variety produced higher total bulb and true seed yields than other varieties under favorable environments with 95.26 and 93.46% coefficient of determination, respectively. the correlations between mean values of environments and improved variety for total bulb (r = 0.976) and seed yields (r = 0.967) were strong and significant. the high mean yields with a large proportion of the variation explained by the environment indicates that the variety responds better to favorable environmental conditions for both bulb and true seed yields than the check onion varieties. wassu et al. improved huruta shallot variety 81 figure 1. improved huruta shallot variety & three onion varieties response to six environments for marketable bulb yield (t/ha) figure 2. improved huruta shallot variety & three onion varieties response to six environments for marketable bulb weight (g) figure 3. improved huruta shallot variety and three onion varieties response to six environments for total bulb yield (t/ha) figure 4. improved huruta shallot variety and three onion varieties response to five environments for seed yield (kg/ha) 5. other quality attributes the bulbs of improved huruta shallot variety had better shelf life than the onion varieties. the proportion of unmarketable bulbs of the improved variety was lower than that of the onion varieties. the improved variety may be preferred by consumers for its large bulb size, deep red bulb color, long shelf life, and high bulb dry matter content. farmers were observed preferring it for its high seed and bulb yields as well as for its high bulb weight and low proportion of unmarketable bulbs. 6. conclusion the improved huruta shallot variety is stable and superior to the commercial onion and shallot varieties for bulb and true seed yields with desirable bulb and true seed quality attributes. the cost of true seed production is much reduced for smallholder farmers. thus, using this variety addresses the serious problem of dearth and scarcity of planting material for shallot production. the high quality of the true seeds and high seed yield of this variety are also attractive for seed business enterprises and smallholder farmers to make substantial profit from seed selling because of the high price of shallot seeds in the world. the seed producing variety also enables breeders to further wassu et al. east african journal of sciences volume 12 (1) 77-82 82 improve shallot through selection from variations created by deliberate and/or natural crossing. in conclusion, the newly released improved huruta variety can be cultivated profitably and sustainably in the mid and highlands of hararghe zones and other places with similar agroecolgy, and could lead to enhanced income livelihood of smallholder farmers. 7. acknowledgements the authors are grateful to the financial support provided by haramaya university for conducting the research for extended periods over several locations. the authors also thank the staff members of horticulture program, school of plant sciences of haramaya university for their technical assistance during field and laboratory work. 8. references currah, l. and proctor, f. j. 1990. onions in troipical regions. bulletin no. 35, p. 245. natural resource institute, chathan, uk. george, r. a. t. 1999. vegetable seed production 2nd edition. cabi publishing 10e 40th street suite 3203, new york, usa. getachew tabor and asfaw zeleke 2004. achievements in shallot and garlic research. research report no. 38. ethiopian agricultural research organization, earo, addis ababa, ethiopia. jackson, t. h., sissay, a., brunko, w., heusser, p., proctor, f. j. and semu nigus. 1985. a practical guide to horticulture in ethiopia, pp. 58-64. horticulture development department, addis ababa ethiopia. kebede woldetsadik. 2003. shallot (allium cepa var. ascolonicum) responses to plant nutrients and soil moisture in a sub-humid tropical climate.dissertation phd dissertation submitted to swedish university of agricultural sciences, sweden. lemma desalegne and shimeles aklilu. 2003. research experience in onion production. research report no. 55, pp. 10-20. ethiopian agricultural research organization, addis ababa, ethiopia. lemma desalegne and yayeh zewide. 1994. varietal development on vegetable crops. pp. 110-130. in: herath, e., lemma dessalegn (eds), horticultural research and development in ethiopia. proceeding of the 2nd horticultural workshop, iar, addis abeba. mengistu hulukal and seid ahmed. 1990. vegetable crops diseases in ethiopia and their control. a mannual, pp. 25-27. alemaya university of agriculture, ethiopia. moanr (ministry of agriculture and natural resources). 2016. crop variety register, issue no. 19, p.2011. addis abeba, ethiopia. pompiliu, m. p., nicolae, n., săulescu, g. i., gabriela, p., leliana, v., ioana, s., sorina, m., eustaţiu, c. and dumitru, n. 2009. grain yield and yield stability of winter wheat cultivars in contrasting weather conditions. romanian agricultural research, 26: 1-8. proctor, f. j. 1987. report on visit to ethiopia to discuss post-harvest storage and handling of allium species 20 march-1 april 1987. tropical development and research institute, overseas development administration, london. rabinowitch, h. d.1990. physiology of flowering. in: rabinowitch, h. d. and brewster, j. l. (eds.). onion and allied crops. volume 1, pp 113-114. crc press, boca raton, florida, usa. shimeles aklilu. 2014. the performance of true seed shallot lines under different environments of ethiopia. journal of agricultural sciences, 59: 129-139. van nocker, s. 2001. the molecular biology of flowering. horticulture reviews, 27: 1-39. ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(2): 225-232 licensed under a creative commons *corresponding author: sewagegnetariku@gmail.com attribution-noncommercial 4.0 international license. registration of “takusa” tef [eragrostis tef (zucc) trotter] variety sewagegne tariku1*, gedefaw misganaw1, misganaw ferede1, atalay fentahun1, atinkut fentahun1, yismaw deginetu2, sefinew wale1, zigale dagnaw1, and awolachew ayifokru3 1adet agricultural research center, p.o. box 8, bahir dar, ethiopia 2gondar agricultural research center, p.o. box 1337, gondar, ethiopia 3debre berhane agricultural research center, p.o. box 112, debre berhane, ethiopia abstract background: tef is the most important staple food and it takes the largest share in annual area crop coverage in ethiopia. however, the productivity of the crop is far below its potential. limited availability of stable and high yielding improved varieties and wider use of low yielding farmers’ cultivars is one of the major factors constraining tef productivity. objective: the objective of the research was to identify and release stable and high yielding tef genotypes with desirable agronomic and morphological traits materials and methods: eighteen tef genotypes including takusa [dz-01-974*ga-10-3 (ril-104)] plus the standard (abay) and local checks were evaluated in a regional variety trial at adet, mota, bichena, takusa and alem ketema districts in northwestern part of ethiopia during the 2018 and 2019 main rainy cropping seasons in a randomized complete block design. results: the results of the combined analysis of variance for grain yield across 10 environments revealed that the new variety, takusa was the highest yielder among the tested genotypes. the results of genotype plus genotype by environment interaction (gge) biplot analysis revealed that takusa was the most stable and high yielding (2.4 t ha–1) genotype from among the tested genotypes. it showed 16.7% yield advantage over the standard check, abay. conclusion: takusa gained farmers’ acclaim and acceptance for its high grain and biomass yields, wider adaptation and other desirable agronomic and morphological traits such as white seed color, medium time of maturity, and moderate tolerance to lodging. takusa tef variety was officially approved for cultivation in 2021 in adet, mota, bichena, takusa, alem ketema and similar agro-ecologies in ethiopia. keywords: genotype by environment interaction; genotype and genotype by environment interaction biplot; ideal genotype; lodging tolerance; stability 1. introduction tef [eragrostis tef (zucc) trotter] is originated in ethiopia and it is the first among cereal crops in coverage of cultivated area in different agro-ecologies and serves as a staple food crop for over 70 million people in the country. ethiopian farmers have continued growing tef over the millennia due to its relative merits compared to the other cereal crops with respect to husbandry, utilization, and high market prices (kebebew assefa et al., 2011) as well as short time of maturity that gives it a relative advantage of drought escape over other cereal crops. the nutritional content of tef is comparable to that of the major world cereal crops but it is superior in minerals and essential amino acids (usda, 2015). in recent years, tef has become popular and the demand for its grain has been increasing in the country as a healthy food in the global market because its freedom from gluten and its richness in contents of nutrients (spaenij-dekking et al., 2005). tef is widely cultivated in central and mid north and northwestern parts of the country, including many districts (= woredas) in the amhara regional state around lake tana and in many other places stretching from bahir mailto:sewagegnetariku@gmail.com sewagegne et al. east african journal of sciences volume 16(2): 227-232 226 dar to addis ababa. of the top 25 tef producing woredas in the country, 15 are located in the amhara regional state and the remaining 10 are in oromia regional state (warner et al., 2015). in the main (meher) season of 2019/20, tef production keeps its first rank in terms of area coverage (24.11%) among cereal crops and the crop is produced by over 7.15 million smallholder farmers on about 3.1 million hectares of land with the average grain yield of about 1.85 t ha–1 (csa, 2020). the average tef productivity is low compared to the genetic potential of the crop (up to 6 t ha–1) as indicated by seifu ketema (1993) and the yield potential of tef under optimal management conditions can rich as high as 4.6 t ha–1 (yifru teklu and hailu tefera , 2005). one of the many constraints of tef production is limited availability of stable and high-yielding tef varieties and the widespread use of low yielding local cultivars by the majority of farming community (kibebew assefa et al. 2017; abate bekele et al., 2019). therefore, developing of stable and high-yielding varieties with desirable agronomic traits is an important task to bridge the gap between the ever-increasing demand and supply for the grain of tef in the country and abroad. 2. varietal origin and evaluation takusa (dz-01-974*ga-10-3 (ril-104) was obtained by crossing between dz-01-974 as maternal parent for its high yielding ability and wide adaptability and ga-10-3 353 as a pollen parent for its dwarfism. after a successful crossing was made at debre zeit agricultural research center (dzarc) in 2011, a single-seed, descent method was used to develop recombinant inbred lines with rapid generation advancement up to two to three generations per year using off-season irrigation facilities. takusa together with 19 genotypes of which one standard commercial variety and one farmers’ cultivar as local checks were evaluated at five locations (adet, mota, bichena, takusa and alem ketema) in the amhara regional state. the regional variety trial was conducted for two consecutive years (2018 and 2019 main cropping seasons) in a randomized complete block design with three replications. the genotype obtained from crossing of dz-01-974 x ga-10-3(rill104) was identified as high yielding, widely adaptable, and stable across locations over several years. as a result, the variety was recommended for cultivation in adet, mota, bichena, takusa, alem ketema and similar agro-ecologies in ethiopia named as takusa in 2021. takusa could be cultivated in tef growing agro-ecologies of the country and the objective of presenting the results of this study is to provide information on agronomic performances and stability of the variety for yield to users and to register it as a new variety in ethiopia. 3. grain yield and stability combined analysis of variance for grain yield and other measured parameters of the 20 tef genotypes across the 10 environments revealed significant (p < 0.01) variations due to genotype (g), environment (e) and genotype by environment interaction (gei). takusa (dz-01-974 x ga-10-3 (ril-104) had significantly highest mean grain yield of 2.4 t ha–1 over 10 environments and abay (acc#225931) used as standard check commercial variety produced the second highest mean grain yield of 2.04 t ha–1 but it had non-significant difference with mean grain yield of dzcr-387 x (dz-cr-387 x ga-10-3(rill-96) (g-13). takusa had 0.36 t ha–1 (17.65%) mean yield advantages over the standard check commercial variety (abay) and 0.72 ha–1 (42.86%) mean yield advantages over farmers cultivar included as a local check. takusa was also one of the five genotypes that had significantly higher dry shoot biomass (7 t ha–1) and had 0.5 t ha–1 (7.69%) and 0.3 t ha–1 (4.48%) dry biomass yield advantages over the standard check commercial variety (abay) and farmers’ cultivar, respectively (table 1). tef is primarily grown as human food in ethiopia. however, its straw is highly preferable by cattle as fodder and its price is higher than the straw of other cereals (seifu ketema, 1997). thus, the new variety, takusa had desirable trait of both higher grain dry biomass yields than the standard check and farmers’ varieties. sewagegne et al. registration of “takusa” tef variety 227 table 1. combined mean performance of 20 tef genotypes for grain yield and some other agronomic traits as evaluated in a regional variety trial at 10 environments during the 2018 and 2019 main rainy growing seasons. gc 1 genotype plant parameters 2 dth dtm ph (cm) pl (cm) dsb (t ha–1) gy (t ha–1) g-1 dz-cr-387 x rosea (rill-92) 60.5a 104.8ab 109.8a 39.4a 6.8 b–f 1.58g g-2 dz-cr-387 x alba (rill-279) 59.2bc 103.6a–e 111.6a 39.4a 7.1a–c 1.77c–f g-3 dz-cr-387 x alba (rill-216) 52.3jk 99.3h 96.6gh 32.3e 6.5f–h 1.80 c–f g-4 ga-10-3 x key muri (rill121) 51.4k 102.8a–f 98.0f–h 35.4cd 6.1h 1.82c–e g-5 ga-10-3 x key muri (rill184) 53.7hi 104.1a–d 100.4d–f 34.9d 6.1h 1.78c–f g-6 key muri x 3774-13 (rill-18) 55.5f 101.5c–h 101.9bd 36.2b–d 6.7c–f 1.83c–e g-7 dz-01-974 x ga-10-3(rill17) 56.8de 100.5f–h 103.6bc 35.0 d 6.5e–h 1.69c–f g-8 dz-01-974 x ga-10-3(rill19) 55.3fg 100.4f–h 97.0gh 32.6e 6.4f–h 1.77c–f g-9 dz-01-974 x ga-10-3(rill34a) 58.7c 105.5a 110.0a 40.7a 7.1a–d 1.77c–f g-10 dz-01-974 x ga-10-3(rill47) 59.6a–c 105.0ab 111.8a 40.5a 6.6d–h 1.78c–f g-11 dz-01-974 x ga-10-3(rill50) 55.2fg 99.4gh 96. 0gh 35.1d 6.2f–h 1.66fg g-12 dz-01-974 x ga-10-3(rill66) 53.4ij 102.8a-f 100.8c–f 36.9b 7.1a–d 1.84cd g-13 dzcr-387 x (dz-cr-387 x ga -10-3(rill-96) 54.9f–h 100.5f–h 102.5b–d 37.4b 7.2ab 1.91bc g-14 dz-01-974 x ga-10-3(rill104) 53.7i 99.7gh 98.5e–g 32.8e 7.0 a–e 2.40 a g-15 dz-01-974 x ga-10-3(rill-122b) 52.5jk 100.6e–h 95.5h 33.0e 6.1gh 1.79 c–f g-16 dz-01-974 x ga-10-3(rill72) 57.2d 104.4a–c 104.4b 37.1 b 6.5e–h 1.78c–f g-17 dz-01-974 x ga-10-3(rill83) 54.4g–i 101.3d–h 98.2f–h 36.1b–d 6.5e–h 1.85c g-18 dz-01-974 x ga-10-3(rill84) 57d 102.3b–g 110.1a 37.4b 6.7c–g 1.76c–f g-19 acc#225931 (abay, standard check) 59.9ab 105.2ab 112.6a 40.4a 6.5e–h 2.04b g-20 local check 55.8ef 102.4b–g 101.2c–e 36.8bc 6.7e–f 1.68e–g mean 55.8 102.3 103.1 36.5 6.7 1.8 lsd (5%) 1.1 3.0 2.9 1.4 0.5 0.1 cv (%) 4.0 5.8 5.6 7.6 15.4 16.8 genotype (g) ** ** ** ** ** ** environment (e) ** ** ** ** ** ** g*e ** ** ** ** ** ** note: 1 gc = genotype code. 2 dth = days to heading; dtm = days to maturity; ph = plant height (cm); pl = panicle length; dsb = dry shoot biomass (t ha–1); and gy = grain yield (t ha–1).* and ** significant at p ≤ 5% and p ≤ 1% level of probability, respectively. mean values designated by similar letter(s) had non-significant difference at p < 0.05. lsd = least significant difference at p < 0.05. cv = percentage of coefficient of variation. the genotypes had the highest mean grain yield (2.11 t ha–1) at bichena, followed by 2.09 t ha–1 mean yield at takusa during the 2018 cropping season. the genotypes had the lowest mean grain yield (1.62 t ha–1) at adet during the 2019 cropping season. the mean grain yield performance of takusa coded as g-14 ranged from 2.08 at adet during the 2019 cropping season to 3.01 t ha–1 at takusa during the 2018 cropping season. the check variety, abay had a mean grain yield of about 1.52 t ha–1 at adet in 2019 and 2.36 t ha–1 at bichena in 2018. takusa had better mean grain yield over locations and years than abay variety except at bichena in 2019. takusa had a yield advantage of 7.69% at alem ketema during the 2019 cropping season and 39.75% at alem ketema during the 2018 cropping season. however, it had 3.85% lower yield than abay at bichena in 2019 cropping season (table 2). the results showed yield performances of the genotypes varied over locations and seasons, which evidently proved the presence of gei effect on their yields. in such situations, breeders should look for genotypes that show relatively stable performance across environments. the significant genotype x environment interaction (gei) effects on grain yield has demonstrated that the genotypes responded differently to the variation in environmental conditions. in agreement with the present study, shafii and price (1998) noted that significant gei seriously impaired efforts in selecting superior genotypes in a variety development program. thus, stability analysis for grain yield was conducted using a genotype plus genotype by environment interaction biplot (ggebiplot). the results from gge-biplot for ranking of genotypes relative to an ideal genotype showed that the sewagegne et al. east african journal of sciences volume 16(2): 227-232 228 released variety (takusa) fell very close to the central circle away from the vertical mean line, indicating its high yield potential and wider adaptability compared to the other genotypes subjected to the study (figure 1). according to yan and tinker (2006) and karmizadeh et al. (2013), the genotypes that are very close to the central circle away from vertical mean line are more stable than the genotypes located far away from the concentric circle. table 2. mean grain yield (t ha–1) of 20 tef genotypes across five locations over two years during the 2018 and 2019 main rainy cropping seasons. genotype code adet motta bichena takusa alem ketema li (0–5) a 2018 2019 2018 2019 2018 2019 2018 2019 2018 2019 g-1 1.58 1.51 1.6 1.88 2.05 1.53 1.53 1.35 1.14 1.66 2.6 g-2 1.71 1.59 1.62 2.02 2.01 1.7 1.9 1.94 1.61 1.63 2.4 g-3 1.87 1.86 1.51 2.17 1.83 1.59 1.26 1.66 2.15 2.12 2.6 g-4 2.04 1.96 1.63 2.03 2.1 1.52 2.3 1.12 1.88 1.65 2.3 g-5 1.97 1.77 1.25 1.61 2.07 1.73 2.53 1.23 1.71 1.89 2.4 g-6 1.78 1.74 1.85 1.69 2.22 1.69 2.58 1.44 1.59 1.73 2.3 g-7 1.68 1.69 1.4 2.05 1.96 1.38 2 1.69 1.59 1.43 2.2 g-8 1.95 1.6 1.89 1.75 2.11 1.63 1.77 1.5 1.68 1.89 2.7 g-9 1.87 1.46 1.74 2.34 2.07 1.81 1.49 1.56 1.47 1.84 2.3 g-10 1.95 1.53 1.62 1.84 2.14 1.93 1.78 1.34 1.58 2.11 2.5 g-11 1.73 1.82 1.32 1.73 1.74 1.23 1.95 1.76 1.55 1.79 3 g-12 2.07 1.35 2.0 1.83 2.25 1.4 2.23 1.78 1.74 1.74 2.5 g-13 1.69 1.73 1.82 1.78 2.29 1.82 2.57 1.67 1.98 1.77 2.4 g-14 2.22 2.08 2.25 2.27 2.87 2.25 3.01 2.57 2.25 2.24 1.2 g-15 1.7 1.52 1.7 1.85 2.17 1.72 2.11 2.01 1.44 1.7 2.7 g-16 1.79 1.44 1.5 1.91 1.82 1.71 2.44 1.95 1.73 1.49 2.3 g-17 1.73 1.8 1.61 1.69 2.1 1.8 2.54 1.95 1.57 1.69 2.2 g-18 1.73 1.61 1.62 1.83 1.95 1.71 2.22 1.8 1.6 1.54 2.4 g-19 1.94 1.52 1.87 2.2 2.36 2.34 2.32 2.2 1.61 2.08 2.2 g-20 1.49 1 1.86 1.91 2.2 1.72 1.45 1.63 1.77 1.78 2.9 mean 1.82 1.62 1.67 1.91 2.11 1.7 2.09 1.7 1.67 1.78 cv (%) 11 13.3 15.9 14 11 18.5 19.4 13.8 14.3 14.8 lsd (5%) 0.3 0.4 0.4 0.4 0.4 0.5 0.9 0.3 0.4 0.4 f-value * ** * * * * * ** ** * note: a li (0–5 scale) = lodging index; where, 0 = no lodging and 5 = 100% lodging. * and ** significant difference at p < 0.05 and p < 0.01 probability level, respectively. lsd = least significant difference at p < 0.05. cv = percentage of coefficient of variation. sewagegne et al. registration of “takusa” tef variety 229 figure 1. ranking of genotypes relative to an ideal genotype. genotype code from g1 to g20 represents as listed in table 1. 4. performance of the newly released variety, takusa, in variety verification trial the performance of takusa (dz-01-974 x ga-10-3 (rill-104) for grain yield and other agronomic traits was verified together with the recently released commercial variety, washera (353*keymuri (ril29) as a standard check and a local check from each respective location at adet, mota, and takusa both on station and on farm in 2021 (table 3). the technical committee (tc) which was delegated by the national variety release committee (nvrc) of ethiopia evaluated the verification trial following the variety release guideline. the verification trial data indicated that takusa produced 0.42 t ha– 1(22.34%) mean yield advantages over the standard check commercial variety (washera) and 0.83 t ha–1 (56.46%) mean yield advantages over the farmers’ cultivar subjected to as a local check. takusa produced also a higher dry shoot biomass yield (7.01 t ha–1) and had 0.68 t ha–1 (10.74%) and 0.87 t ha–1 (14.17%) dry shoot biomass yield advantages over the standard check (washera) and farmers’ cultivar, respectively (table 3). therefore, considering the best performance of takusa in both regional and variety verification trials and farmers’ immense interest in the cultivation of this variety as compared to cultivating the standard and local checks, the variety release technical committee (tc) recommended takusa for full release and the recommendation was accepted by the national variety release committee (nvrc). accordingly, takusa (dz01-974 x ga-10-3(rill-104) was officially released in 2021. 5. descriptions of morpho-agronomic characteristics the morpho-agronomic descriptions of newly released variety, takusa is presented in table 4. takusa (dz-01974 * ga-10-3 (ril-104) is characterized by a loose white panicle and white seed color, yellow flower color, semi erect growth habit, an average plant height and panicle length of 98.5 cm, 32.8 cm, respectively. it reaches maturity in a period of 100 days after sowing. it is moderately tolerant to lodging and has a medium maturing time, which fits double cropping calendar. it can be grown at the elevations ranging between 1700 to 2400 meters above sea level. takusa is highly preferred by farmers for its better performance in grain yield, and other desirable agronomic and morphological traits as compared to the other genotypes evaluated in the regional variety trial. there was no any significant disease as well as insect pest incidence and damage observed on the tested genotypes in general and on takusa in particular in the course of the study. sewagegne et al. east african journal of sciences volume 16(2): 227-234 230 table 3 mean performance of takusa, washera (the standard check) and the local check for days to maturity (dtm), dry shoot biomass (dsb) and grain yield (gy) in variety verification trial at adet, mota and takusa both on station (os) and on farm (of) in 2021. variety parameter locations mean adet mota takusa os of1 of2 os of1 of2 os of1 of2 takusa (dz-01-974 x ga-10-3(rill104) dtm 97 105 103 99 95 95 89 79 89 94.56 dsb (t ha–1) 7.61 7.09 7.84 7.50 6.13 5.82 6.94 7.14 7.05 7.01 gy (t ha–1) 2.34 2.22 1.74 2.38 2.29 2.02 2.98 2.40 2.35 2.30 washera [(353*keymuri (ril29) standard check] dtm 108 112 118 109 122 116 104 100 106 110.6 dsb (t ha–1) 7.07 6.59 6.34 6.15 6.38 5.88 5.95 6.26 6.40 6.33 gy (t ha–1) 1.82 1.49 2.02 1.77 2.20 1.93 2.00 1.89 1.77 1.88 local check dtm 106 106 102 110 120 115 87 73 94 101.44 dsb (t ha–1) 5.89 6.08 7.56 6.77 6.14 5.98 5.79 5.36 5.67 6.14 gy (t ha–1) 1.51 1.50 1.34 1.53 1.31 1.43 1.46 1.63 1.53 1.47 table 4. descriptions of morpho-agronomic characteristics of takusa variety released in 2021. characteristic parameter description of agronomic/morphological characteristics variety name: takusa (dz-01-974 * ga-10-3 (ril-104) adaptation area: adet, mota, bichena, takusa , alem ketema in western amhara regional state and similar agro ecologies in ethiopia altitude (meter above sea level): 1700–2400 rainfall (mm): 800–1300 seed rate (kg ha–1): 15 planting date: late june to july depending on the onset of rainfall spacing: 20 cm between rows for row drill planting fertilizer rate (kg ha– 1): n = 17, p2o5 = 60, for red soil n = 64, p2o5 = 40, for black soil days to heading: 45–60 days to mature: 93–113 panicle length (cm): 30–41 plant height (cm): 96–113 1000 seed weight (g): 0.3 seed color: white flower color: variegated (yellow) growth habit: semi erect panicle form: loose leaf arrangement: horizontal and bending lodging index (0–5 scale) a 1.2 grain yield (t ha–1): research field = 2.08–3.01 farmers’ field = 1.7–2.4 year of release: 2021 breeder/maintainer: adet agricultural research center (aarc) merits of the variety: it is medium maturing which fits a double cropping calendar and has moderate tolerance to lodging note: a lodging index (0–5 scale); where, 0 = no lodging and 5 =100 % lodging. sewagegne et al. registration of “takusa” tef variety 231 6. conclusion takusa (dz-01-974*ga-10-3 (ril-104) tef variety produced significantly higher grain yield and showed wider adaptation to agro-ecologies than the standard check variety and other genotypes evaluated. the results of gge-biplot analysis revealed that takusa is a stable and high yielding tef variety with 17.6% yield advantage over the standard check variety, abay. takusa is highly preferred by farmers for its high grain yield, white seed color, and has a moderate lodging tolerance. it has also a medium duration of maturity, which makes it fit for practicing double cropping. therefore, the variety has been officially released for wider cultivation in northwestern ethiopia (adet, mota, bichena, takusa, alem ketema) and areas with similar agro-ecologies in the country. 7. acknowledgements the authors thank amhara regional agricultural research institute (arari) for financing the study. debre zeit agricultural center is acknowledged for providing the genotypes. 8. references abate bekele, solomon chanyalew, tebkew damte, nigussu husien, yazachew genet, et al. 2019. cost-benefit analysis of new tef (eragrostis tef) varieties under lead farmers’ production management in the central ethiopia. ethiopian journal of agricultural science, 29(1): 109–123. csa (central statistical agency). 2020. agricultural sample survey 2019/20 volume i. report on area and production of major crops (private peasant holdings, meher season). statistical bulletin 587, april 2020, addis ababa, ethiopia. karimizadeh, r., mohtasham, m.n., sabaghn, a.a., mahmood, b. and roustami, f. 2013. gge biplot analysis of yield stability in multienvironment trials of lentil genotypes under rainfed condition. notulae scientia biologicae, 5(2): 256–262. kebebew assefa, sherif aliye, getachew belay, gizaw metaferia, hailu tefera and sorells, m.e. 2011. quncho: the first popular tef variety in ethiopia. international journal of agricultural sustainability, 9(1): 25–34. doi: 10.3763/ijas.2010.0545. kebebew assefa, solomon chanyalew and zerihun tadele. 2017. tef, eragrostis tef (zucc) trotter. pp. 226–266. in: patil, j.v. (ed.). millets and sorghum bbiology and genetic improvement. wiley, hoboken. seyfu ketema. 1993. tef (eragrostis tef): breeding, genetic resources, agronomy, utilization and role in ethiopian agriculture. institute of agricultural research, addis ababa, ethiopia. pp. 102. seifu ketema. 1997. tef [eragrostis tef (zucc) trotter.] promoting the conservation and use of underutilized and neglected crops. institute of plant genetics and crop plant research, gatersleben. international plant genetic resources institute, rome, italy. pp. 1–52. shafii, b. and price, w.j. 1998. analysis of genotype-byenvironment interaction using the additive main effects and multiplicative interaction model and stability estimates. journal of agricultural, biological, and environmental statistics, 3(3): 335–345. spaenij-dekking, l., kooy-winkelaar, y. and koning, f. 2005. the ethiopian cereal tef in celiac disease. the new england journal of medicine, 353(16): 1748– 1749. usda (us department of agriculture). 2015. agricultural research service, nutrient data laboratory. usda national nutrient database for standard reference, release 27. pp. 128. avialable at http://www.ars.usda.gov/ba/bhnrc/ndl. warner, j., stehulak, t. and leulsegged kasa. 2015. woreda-level crop production rankings in ethiopia: a pooled data approach. international food policy research institute (ifpri), addis ababa, ethiopia. yan, w. and tinker, n.a. 2006. biplot analysis of multi– environment trial data: principles and applications. canadian journal of plant sciences, 86: 623–645. yifru teklu and hailu tefera. 2005. genetic improvement in grain yield potential and associated agronomic traits of tef (eragrostis tef), euphytica, 141: 247–254. http://www.ars.usda.gov/ba/bhnrc/ndl sewagegne et al. east african journal of sciences volume 16(2): 227-232 232 ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(2): 171-186 licensed under a creative commons *corresponding author: teshome.geremew@astu.edu.et attribution-noncommercial 4.0 international license. knowledge, attitude, and management practices of stakeholders towards fungal invasion and mycotoxin contamination of wheat and maize in ethiopia teshome geremew biru* and zerihun belay gemta department of applied biology, school applied natural science, adama science and technology university, p. o. box 1888, adama ethiopia abstract background: filamentous fungi cause deterioration in grain quality and release harmful mycotoxins. cereals are vulnerable to fungal invasion and mycotoxin contamination starting from the field to postharvest storage and processing. however, information is limited on the fungal invasion of cereals and mycotoxin contamination in ethiopia. objective: the study was aimed at determining the knowledge, attitude, and management practices of respondents towards fungi and their mycotoxin contaminations. materials and methods: a total of 438 participants were sampled from four top wheat and maize producing zones (bale, west arsi, east shoa, and west shoa) from oromia regional state, ethiopia. descriptive analysis, mean ranking, and test of significances were used to analyze the data. results: based on the results obtained, the overall mean score level of knowledge of respondents towards fungal invasion and mycotoxin contamination was very low (1.81). the highest mean score level of knowledge towards fungal invasion and mycotoxin contamination was 2.54 for respondents working as agricultural experts and the minimum score (1.31) was obtained for respondents with elementary educational background. a significant difference in mean knowledge level (p < 0.01) was observed on the questions related to fungi and their mycotoxins among farmers, agricultural experts, merchants, teachers and other participants. the overall mean attitude level of respondents was 4.16. the highest mean attitude level (4.49) was obtained for teachers and the lowest mean attitude level (3.94) was obtained for respondents with elementary education background. the overall mean practice level of respondents towards reducing fungal infection and mycotoxin contamination was low (1.9). a comparison of mean practice levels base on occupation type showed significant (p < 0.01) differences among the various occupation types. conclusion: the study revealed knowledge about fungi and mycotoxin contamination is generally very low among farmers. this signals the need for providing training for farmers at all levels on toxin producing fungi and the danger of their mycotoxins present to humans and animals. keywords: attitude; cereals; knowledge; occupation type; respondents 1. introduction wheat (triticum aestivum l.) and maize (zea mays l.) are important sources of carbohydrate and constitute the dominant portion of staple cereals in ethiopia both in urban and rural areas (sheehy et al., 2019). these cereals are vulnerable to fungal invasion and mycotoxin contamination starting from the field to post-harvest storage and processing until being served on a table (ünüsan, 2019; leite et al., 2020). the majority of the farmers in the country are way back from good agricultural practices, and the crops produced are highly subjected to fungal invasion and mycotoxin contamination (haftom kebede et al., 2020). beside the poor agricultural practice, the fungi take advantage of the warm climatic condition of the country to invade the grains and release their toxic secondary metabolites into the grains (temba et al., 2021). these aforementioned conditions are aggravated by the lack of awareness about the conditions favoring fungal growth and proliferation. mailto:teshome.geremew@astu.edu.et teshome and zerihun east african journal of sciences volume 16(2): 171-186 172 fungal invasion on wheat and maize reduces the visual quality of the grain and results in a deteriorated price of the grain. fungal invasion before harvest could unstoppably lead to post-harvest grain deterioration, quality loss, price reduction, and consumer health hazards (schmidt et al., 2016). this grain quality loss and health hazards are many-fold in developing countries like ethiopia where manual harvesting and threshing of grains are widely practiced (wondimeneh taye et al., 2018). fungi are a highly diverse group of organisms capable of colonizing diverse substrates and impart their mycotoxins to the substrate (leite et al., 2020). mycotoxins are fungal secondary metabolites that are toxic to human and animal cells of which the dominant mycotoxins are produced by fungi belonging to the genera aspergillus, fusarium, penicillium, and alternaria (geremew teshome et al., 2016; escriva et. al, 2017). the major mycotoxins based on their occurrence and impact on human and animal health comprises aflatoxins, ochratoxins, fumonisins, trichothecenes, deoxynevalinone, citrinine, and patuline (schmidt et al., 2016). among these mycotoxins aflatoxins are the most carcinogenic of all naturally occurring fungal secondary metabolites produced by aspergillus flavus and aspergillus parasiticus (temesgen asefa et al., 2020). ochratoxins are mainly produced by a diverse group of filamentous fungi among the genus aspergillus including aspergillus westerdijkiae, aspergillus ochraceus, and aspergillus steynii, and by the genus penicillium (p. notatum) (geremew teshome et al., 2016; escriva el al., 2017). ochratoxins exerts nephrotoxic, hepatotoxic, genotoxic, immunosuppressive, and carcinogenic effects on animal cells (iarc, 1993; sorrenti et al., 2013). fumonisins are produced by fusarium verticillioides and f. proliferatum, and penicillium fumonisins (deepa et al., 2016) targeting kidneys and liver (ünüsan, 2019). these mycotoxins have ever raised human and animal health concerns due to their wider occurrence in different agricultural products. fungal toxins can occur in different cereal grains like maize, sorghum, wheat, rice, barley, and oat and animal feeds (ogunade et al., 2018). the toxin-producing fungi possibly get access to the cereals during pre-harvest, during harvest, or post-harvesting during storage and processing. once toxin producing fungi get access to the grains or any other product destined for human consumption dietary exposure to mycotoxin will follow (atongbiik et al., 2017). food processing practices like grinding, juice extraction, fermenting, roasting, boiling, could not result in the complete removal of mycotoxins from the food commodities (pallarés et al., 2019). several reports showed the dietary exposure of human to different mycotoxins trigger acute or chronic toxicity (pallarés et al., 2019; vin et al., 2020). in developing countries where the poor agricultural practice coupled with food insecurity, the already disadvantageous communities consume low-quality cereals and become more vulnerable to mycotoxin dietary exposure. fungal invasion and preventive measures against their mycotoxins are based on the understanding of the prevailing environmental conditions for the proliferation and spread of the fungi and their spores. ethiopian wheat and maize producing farmers have some indigenous knowledge on how to protect their crops from insect and pest infestation during preand post-harvest processing (duressa tarekegn 2018; birhanu hiruy and emana getu, 2018). however, it was hypothesized that the farmers might have no adequate knowledge of the nature of toxin producing fungi, mycotoxins and their health impacts, and the prevention mechanism to fungal invasion. it was speculated that lack of understanding of these fungi and mycotoxins leads to the consumption of wheat and maize invaded by the fungi. thus, the main objective of this study was to investigate the knowledge, attitude, and practices of stakeholders towards fungi and mycotoxins in maize and wheat. therefore, this study was conducted to determine the variable most affecting the practice of participants in reducing fungal invasion and mycotoxin contamination in wheat and maize production. 2. material and methods 2.1. study locations, participants, and design a total of 438 participants were selected based on quota sampling from top maize and wheat-producing zones of oromia regional state (figures 1, 2 and 3). seven top wheat and maize producing districts were selected based on their production potential and the respondents included were farmers, agricultural experts (aes), merchants, teachers, and other consumers. the participants in the study districts were drawn from eight towns and 16 rural villages based on quota sampling techniques. zonal administrations, districts, and villages were selected based on maize and wheat production potential. the study was designed to obtain a better composition of participants from all sampling districts. teshome and zerihun fungal and mycotoxin contamination of wheat and maize 173 figure 1. absolute location map of west shoa zone, oromia national regional state of ethiopia. figure 2. absolute location map of east shoa zone, oromia national regional state of ethiopia. teshome and zerihun east african journal of sciences volume 16(2): 171-186 174 figure 3. absolute location map of east show, bale and west arsi zones of oromia national regional state of ethiopia. sixteen interview administrators with a minimum academic qualification of diploma were recruited and trained for two days on how to perform a survey and administer interview questions. a simple manual was prepared for the interview administrator and pretested during the time of selecting respondents. the survey was conducted from 20 january to 4 february 2018. a team consisting of three individuals (two trained interview administrators and one agricultural extension worker as a village guide) with all the necessary facilities was deployed to every district. sampling of the respondents was based on the quota method and once the quota was allocated, interview administrators began from the center of the village and proceeded towards the east side of the village by sampling every third household. in case, a household head was not available for the interview, the next household was sampled and the procedure continued eastwards until all the targeted households were interviewed. once eastward households were all interviewed, the same procedure was followed starting from the center to the west, north, and south until the required respondents were obtained. 2.2. administering questionnaires three categories of questionnaires were prepared to capture knowledge, attitude, and practice of respondents. the first category contained knowledge-related questions, the second category contained attitude-related and the third category contained practice-related questions. a team containing two individuals per village administered the questionnaires. a principal investigator and a coinvestigator were assigned to supervise the interview administration process. all the questionnaire administrators were trained and their competence in questionnaire administration skills was deemed satisfactory based on a pretesting exercise. before administering the questioners, verbal consent was obtained using a standardized consent script. the questionnaires were administered in local languages (afaan oromo or amharic). the completed questionnaires were manually checked for clarity and completeness and coded before being entered into epi info. the data were exported to microsoft excel and analyzed using r statistical software and spss v20. 2.3. data analysis for statistical evaluation of the data r statistical software version 3.0.3, spss version 20, and microsoft excel were used. pearson correlation analysis was performed to see the relationship between socio-demographic factors and mean knowledge level. descriptive analysis was carried out to summarize the socio-demographic characteristics teshome and zerihunn fungal and mycotoxin contamination of wheat and maize 175 of the respondents based on frequency distribution and percentages. mean ranking analysis was used to understand the stakeholders’ knowledge, attitude and management practice level towards fungal invasion and mycotoxin contamination. kruskal wallis test (α = 0.05) was performed to examine significant differences between the mean knowledge, attitude, and practice levels of the respondents. 3. results 3.1. socio-demographic characteristics of the respondents the results of the socio-demographic characteristics showed that 75% of the respondents were male and 25% were female (table 1). one hundred and forty-one (32.2%) of the participants were aged between 31 to 40 years. one hundred and thirty-three (30.4%) of the respondents were in the age group of 21 to 30 years. the remaining 93 (21.2%) and 58 (13.2%) of the participants were aged between 41 and 50, and above 50 years, respectively. some 13 (3%) of the participants were between the age of 18 and 20 years. three hundred and seventy-five (85%) of the respondents were married and the remaining 47 (10.7%), nine (2.1%), and seven (1.6%) were single, widowed, and divorced, respectively. 3.2. knowledge of respondents towards fungi invasion and mycotoxin contamination on wheat and maize the overall mean score level of knowledge of respondents towards fungal invasion and mycotoxin contamination was very low (1.81) (table 2). the highest mean score level of knowledge towards fungal invasion and mycotoxin contamination was 2.54 for respondents working as agricultural experts and the minimum score (1.31) was obtained for respondents with the background of elementary education (figure 4). no significant difference was observed in the level of knowledge between males and females (p > 0.05) (table 3 table 1. socio-demographic profile of the respondents in the four administrative zones of oromia national regional state during the 2018 cropping year. variable variable class frequency percent gender male 327 74.7 female 111 25.3 total 438 100 age <20 13 3 21-30 133 30.4 31-40 141 32.2 41-50 93 21.2 51 and above 58 13.2 total 438 100 marital status divorced 7 1.6 married 375 85.6 single 47 10.7 widowed 9 2.1 total 438 100 educational status no education 98 22.4 grade 1-4 64 14.6 grade 5-8 118 26.9 grade 9-12 73 16.7 diploma and above 85 19.4 total 438 100 occupation 1. farmers 236 53.9 2. merchant 53 12.1 3. agricultural expert 19 4.3 4. teacher 18 4.1 5. other 112 25.6 total 438 100 teshome and zerihun east african journal of sciences volume 16(2): 171-186 176 table 2. mean knowledge level of respondents in four administrative zones of oromia national regional state during the 2018 cropping year. statements capturing knowledge of respondents responses standard deviation 1(no) 2(not sure) 3(yes) mean number % number % number % have you ever heard about the name fungi/mold 108 24.7 49 11.2 281 64.2 2.39 0.86 have you heard of the word mycotoxin 362 82.6 23 5.3 53 12.1 1.29 0.67 have you heard of the word afflation 270 61.6 25 5.7 43 9.8 1.25 0.62 have you heard of the word ochratoxin 422 96.3 0 0.0 16 3.7 1.08 0.38 have you heard of the word fumonisin 394 90.0 26 5.9 18 4.1 1.14 0.45 have you heard about mycotoxins occurrence in maize 298 68.0 5 1.1 135 30.8 1.63 0.92 have you heard about mycotoxins occurrence in wheat 288 65.8 37 8.4 113 25.8 1.60 0.87 do you know that mycotoxins can cause disease 129 29.5 67 15.3 242 55.3 2.26 0.88 do you know that mycotoxins can cause stunting 184 42.0 144 32.9 110 25.1 1.83 0.80 do you know that mycotoxins can cause cancer 203 46.3 157 35.8 78 17.8 1.71 0.75 do you know that mycotoxins can suppress immunity 160 36.5 149 34.0 129 29.5 1.93 0.81 do you know that mycotoxins can harm livestock 224 51.1 91 20.8 123 28.1 1.77 0.86 do you know that mycotoxins survive cooking temperature 198 45.2 127 29.0 113 25.8 1.81 0.82 do you know that mycotoxins accumulate in animal products 205 46.8 127 29.0 106 24.2 1.77 0.81 do you know that the ware houses hold be checked frequently 141 32.2 21 4.8 276 63.0 2.31 0.93 do you know that wheat and maize should be free from mites and insects 154 35.2 8 1.8 276 63.0 2.28 0.95 do you know that mycotoxin can cause stomachache 146 33.3 48 11.0 244 55.7 2.22 0.93 do you know that mycotoxins can cause headache 205 46.8 104 23.7 129 29.5 1.83 0.86 do you know that mycotoxins can cause fever 204 46.6 121 27.6 113 25.8 1.79 0.83 do you know that mycotoxins can cause vomiting 174 39.7 105 24.0 159 36.3 1.97 0.87 do you know that molds are harmful to human and animals 141 32.2 56 12.8 242 55.3 2.23 0.91 mean and standard deviation 1.81 0.15 teshome and zerihunn fungal and mycotoxin contamination of wheat and maize 177 table 3. knowledge of respondents by gender and occupation types in four administrative zones of oromia national regional state during the 2018 cropping year. statements capturing knowledge of respondents gender occupation male female farmers agricultur al experts teachers merchants others have you ever heard about the name fungi/mold 2.45 2.24 2.06 3.00 2.89 2.83 2.72 have you heard of the word mycotoxins 1.32 1.23 1.15 2.58 1.56 1.30 1.34 have you heard of the word aflation 1.28 1.17 1.11 2.53 1.44 1.19 1.33 have you heard of the word ochratoxin 1.10 1.00 1.03 1.63 1.11 1.00 1.09 have you heard of the word fumonisins 1.15 1.11 1.08 1.74 1.28 1.09 1.17 have you heard about mycotoxins occurrence in maize 1.61 1.68 1.48 2.79 1.89 1.94 1.55 have you heard about mycotoxins occurrence in wheat 1.60 1.59 1.50 2.47 1.89 1.68 1.58 do you know that mycotoxins can cause disease 2.31 2.10 1.97 2.84 2.56 2.45 2.62 do you know that mycotoxins can cause stunting 1.84 1.79 1.72 2.37 2.28 1.92 1.86 do you know that mycotoxins can cause cancer 1.70 1.76 1.56 2.37 1.94 1.85 1.82 do you know that mycotoxins can suppress immunity 1.94 1.90 1.74 2.63 2.50 1.89 2.14 do you know that mycotoxins can harm livestock 1.78 1.73 1.58 2.74 2.17 1.83 1.90 do you know that mycotoxins survive cooking temperature 1.83 1.73 1.68 2.16 2.00 1.96 1.90 do you know that mycotoxins accumulate in animal products 1.79 1.73 1.60 2.68 2.11 1.91 1.88 do you know that the warehouse should be checked frequently 2.38 2.11 2.04 2.74 2.50 2.58 2.63 do you know that cereals should be free from mites and insects 2.34 2.11 1.99 2.68 2.39 2.64 2.63 do you know that mycotoxins can cause stomachache 2.30 2.00 1.92 2.95 2.61 2.36 2.61 do you know that mycotoxins can cause headache 1.85 1.77 1.67 2.63 2.28 1.87 1.92 do you know that mycotoxins can cause fever 1.80 1.78 1.67 2.42 2.11 1.81 1.89 do you know that mycotxins can cause vomiting 2.00 1.87 1.76 2.58 2.28 2.08 1.89 do you know that molds are harmful to human and animals 2.28 2.08 1.92 2.89 2.78 2.57 2.20 mean 1.84 1.74 1.63 2.54 2.12 1.94 1.94 teshome and zerihun east african journal of sciences volume 16(2): 171-186 178 comparison of mean knowledge level among the participants with various occupational types indicated that agricultural expertise has a higher knowledge level (2.54), and farmers have the lowest mean knowledge level (1.63) (table 3). a significant difference in mean knowledge level (p < 0.00) was observed on the question related to fungi and their mycotoxins. post hock test using kruskalmc test revealed the determining factors were higher education level and being an expert in the agricultural area. in this study, the knowledge level of respondents towards fungi and mycotoxin showed increasing with a better improved educational level (figure 4). however, the difference in mean knowledge level is not statistically significant (p > 0.05). figure 4. median knowledge level of respondents by educational background (box = interquartile range, bold lines = median values, lower and upper hinges = lower and higher values). 3.3. attitude of respondents on fungi invasion and mycotoxin the attitude of respondents towards reducing fungal infection and mycotoxin contamination in wheat and maize was presented in table 4. the overall mean attitude level of respondents (4.16) showed the participants had a favorable attitude towards fungal infection and mycotoxin contamination in wheat and maize. the highest and the lowest mean attitude level, 4.49 and 3.94 (table 5) were obtained from teachers and elementary educational background, respectively. no significant differences in attitudinal levels was observed between male and female (p > 0.77), among occupation type (p > 0.53), and educational background (p > 0.59). the majority of the respondents (97.3%) had a favorable attitude in response to the first two questions synthesized to capture the attitude of the responses (table 4). however, all respondents did believe in consuming or selling moldy wheat and maize. additionally, all respondents had no favorable attitude towards testing maize and wheat for mycotoxin (table 4). teshome and zerihunn fungal and mycotoxin contamination of wheat and maize 179 table 4. attitude of respondents towards fungal infection and mycotoxin contamination in wheat and maize in four administrative zones of oromia national regional state during the 2018 cropping year. note: 1 = strongly disagree; 2 = disagree; 3 = neutral; 4 = agree; and 5 = strongly agree. table 5. the attitude of respondents in relation to gender, occupation, and educational background in four administrative zones of oromia national regional state during the 2018 cropping year. statements to capture respondents attitude responses strongly disagree disagree neutral agree strongly agree mean standard deviation no. % no. % no. % no. % no. % i believe cereals should be stored in dry and clean storage material 1 0.2 9 2.1 2 0.5 112 25.6 314 71.7 4.66 0.62 i believe that cereals should be transported appropriately packed and don’t be re-wet 6 1.4 11 2.5 6 1.4 144 32.9 271 61.9 4.51 0.77 i believe that moldy cereals should not be consumed or soled 27 6.2 104 23.7 12 2.7 125 28.5 170 38.8 3.7 1.35 i believe that testing maize and whet for mycotoxin is important 47 10.7 37 8.4 28 6.4 184 42 142 32.4 3.77 1.28 mean and standard deviation 4.16 0.36 statements to capture respondents attitude gender occupation educational background male female farmers agri. experts teachers merchants others no education elem. junior high school diploma and above i believe cereals should be stored in dry and clean storage material 4.69 4.58 4.67 4.84 4.56 4.42 4.76 4.74 4.57 4.70 4.73 4.58 i believe that cereals should be transported appropriately packed and don’t be re-wet 4.57 4.33 4.52 4.53 4.44 4.36 4.58 4.53 4.48 4.42 4.63 4.53 i believe that moldy cereals should not be consumed or soled consumed or soled 3.68 3.77 3.68 3.95 4.39 3.47 3.71 4.10 3.38 3.60 3.66 3.68 i believe that testing maize and whet for mycotoxin is important 3.78 3.75 3.60 4.21 4.56 3.89 3.87 3.69 3.34 3.66 3.90 4.08 mean 4.18 4.11 4.12 4.38 4.49 4.03 4.23 4.27 3.94 4.10 4.23 4.22 teshome and zerihun east african journal of sciences volume 16(2): 171-186 180 3.4. management practice of respondents towards fungi invasion and mycotoxin the result indicated in table 6 showed the management practice of the respondent applied to minimize fungal invasion and mycotoxin contamination of wheat and maize. the overall mean management practice level of respondents towards reducing fungal infection and mycotoxin contamination was low (1.9) (table 6). the mean practice level obtained for males (1.94) was slightly higher than the mean practice level obtained for females (1.84) (table 7). however, there was no significant (p > 0.05) difference between the mean practice levels obtained for males and females. mean practice level to reduce fungal infection and mycotoxin contamination obtained for agricultural experts, merchants, teachers, and farmers were 2.35, 2.15, 2.13, and 1.73, respectively (table 7). comparison of mean practice levels based on occupation types showed significant (p < 0.01) differences among the various occupation types. comparison of mean management practice levels base on the educational background (figure 5), also showed significant differences among respondents with various educational backgrounds. the mean values of the practice levels were positively correlated with increasing education levels (figure 5). the highest (2.2) and the lowest (1.34) mean practice levels were obtained for respondents with higher educational levels than diploma and elementary education levels respectively. teshome and zerihunn fungal and mycotoxin contamination of wheat and maize 181 table 6. management practice of applied by respondent households to minimize fungal infection and mycotoxin contamination in wheat and maize. practice of respondents to reduce fungal infection responses 1(no) 2(not sure) 3(yes) mean standard deviation number % number % number % protect wheat and maize from contamination by soil and animal excreta 160 36.5 101 23.1 177 40.4 2.04 0.88 use moldy wheat and maize at home 259 59.1 142 32.4 37 8.4 1.49 0.65 check quality before buying for visible mold overgrowth 111 25.3 87 19.9 240 54.8 2.29 0.85 check regularly the storage for insect, rodents, and dampness at home or warehouse 94 21.5 115 26.3 229 52.3 1.97 0.80 check the storage temperature 160 36.5 130 29.7 148 33.8 1.97 0.87 use moldy grains for making traditional beverage/tella/ 231 52.7 119 27.2 88 20.1 1.67 0.79 store inadequately dried grain 337 76.9 5 1.1 96 21.9 1.45 0.83 place grains on bare soil ground 256 58.4 20 4.6 62 14.2 1.33 0.71 keep wheat and maize in humid leaky soil 339 77.4 6 1.4 63 14.4 1.30 0.71 eat foods with visible mold over growth 346 79.0 0 0.0 92 21.0 1.42 0.82 early planting 182 41.6 58 13.2 198 45.2 2.20 0.95 crop rotation 176 40.2 31 7.1 231 52.7 2.13 0.96 proper soil nutrient management 183 41.8 44 10.0 221 50.5 2.06 0.95 varity selection 190 43.4 31 7.1 217 49.5 2.06 0.96 irrigation 294 67.1 79 18.0 65 14.8 1.48 0.74 insecticides 185 42.2 21 4.8 232 53.0 2.11 0.97 timing of harvest 170 38.8 23 5.3 245 55.9 2.11 0.97 hand sorting 189 43.2 41 9.4 208 47.5 2.17 0.96 adequate/rapid drying 127 29.0 3 0.7 308 70.3 2.41 0.91 avoiding of floor contact 152 34.7 20 4.6 266 60.7 2.26 0.94 rodent control 177 40.4 19 4.3 242 55.3 2.15 0.97 winnowing 189 43.2 37 8.4 212 48.4 2.05 0.96 mean and standard deviation 1.91 0.10 teshome and zerihun east african journal of sciences volume 16(2): 171-186 182 table 7. the practice of respondents to reduce fungal infection and mycotoxin contamination based on gender and occupation. practice of respondents to reduce fungal infection gender occupation male female farmers ae teachers merchants others protect wheat and maize from contamination by soil and animal excreta 2.1 1.9 1.8 2.3 2.0 2.1 2.4 use moldy wheat and maize at home 1.5 1.5 1.5 1.7 2.0 1.5 1.5 check quality before buying for visible mold overgrowth 2.3 2.2 2.0 2.6 3.0 2.5 2.6 check regularly the storage for insect, rodents, and dampness at home or warehouse 2.4 2.2 2.1 2.5 3.0 2.6 2.6 check the storage temperature 2.0 1.9 1.9 2.1 2.0 2.1 2.1 use moldy grains for making traditional beverage/tella/ 1.7 1.7 1.6 1.8 2.0 1.8 1.7 store inadequately dried grain 1.4 1.6 1.4 1.9 1.0 1.8 1.4 place grains on bare soil ground 1.3 1.3 1.2 1.8 1.0 1.5 1.3 keep wheat and maize in humid leaky soil 1.3 1.4 1.2 2.0 1.0 1.6 1.3 eat foods with visible mold overgrowth 1.4 1.4 1.3 1.6 1.0 1.5 1.6 early planting 2.1 2.0 1.9 2.4 2.0 2.2 2.2 crop rotation 2.2 2.0 1.9 2.6 2.0 2.3 2.4 proper soil nutrient management 2.1 2.0 1.9 2.5 2.0 2.3 2.2 varity selection 2.1 1.9 1.9 2.5 2.0 2.2 2.3 irrigation 1.5 1.5 1.3 2.2 2.0 1.6 1.5 insecticides 2.1 2.0 1.9 2.6 3.0 2.2 2.4 timing of harvest 2.2 2.0 1.9 2.7 3.0 2.6 2.4 hand sorting 2.1 2.0 1.8 2.7 2.0 2.5 2.1 adequate/rapid drying 2.5 2.2 2.1 2.9 2.6 2.8 2.8 avoiding of floor contact 2.3 2.2 2.0 2.8 3.0 2.7 2.5 rodent control 2.2 2.0 1.9 2.8 3.0 2.4 2.5 winnowing 2.1 1.9 1.8 2.5 2.0 2.4 2.2 mean 1.9 1.9 1.7 2.4 2.1 2.2 2.1 note: ae = agricultural experts. teshome and zerihunn fungal and mycotoxin contamination of wheat and maize 183 figure 5. management practice of respondents towards minimizing fungal infection and mycotoxin contamination in relation to the educational background (box = interquartile range, bold lines = median values, lower and upper hinges = lower and higher values). 4. discussion the results of this study have demonstrated that the participants have a low mean knowledge level towards fungi and their mycotoxin. the majority of the respondents had little or no knowledge about the fungal invasion and their mycotoxins contamination in maize and wheat. this can be interpreted as a lack of awareness about fungi and their mycotoxin leads to a strong assumption that the community is at risk of fungalderived mycotoxins. the result of this study is in line with the previous report from malawi (matumba et al., 2016) that revealed the lack of information on the health implication of fungal contamination and their mycotoxins in moldy foods and feedstuffs. a study from malaysia (sabran et al., 2012) also revealed a low level of respondents' knowledge regarding fungi and aflatoxin contamination in food commodities. a study by matumba et al. (2016) showed that 98% of respondents were unaware of mycotoxin contamination in different fermented foods. however, the study reported by mohd azaman et al., 2016 indicated that a specific group of population linked with peanut-based productions has adequate knowledge, favorable attitude, and high hygiene practices towards aflatoxins contamination in peanutbased products with mean scores greater than average. it seems that most of the awareness creation activities in most parts of the world were associated with the risk of well-known aflatoxin contamination in peanut products (mohd azaman et al., 2016; kibret belayhun et al., 2019). the critical shortage of knowledge about fungi and mycotoxin underscores the need for awareness creation and education for the public in the study area. analysis of the socio-demographical background of the respondents showed a better understanding of fungal infection and their mycotoxins as educational level increase. the most vulnerable portion of the population was the least educated group with little or no knowledge of fungi and mycotoxins. mycotoxin studies focusing on africa highlighted that due to the poor socio-economic conditions, most africans are forced to consume mycotoxin contaminated food products and subsequently suffer from related health complications (geremew teshome et al., 2016; tola marta and kebede bedaso, 2016; haftom kebede et al., 2020). the overall mean attitude level of respondents (4.16) obtained in this finding showed that the participants had a favorable attitude towards fungal infection and mycotoxin contamination in wheat and maize. the lowest mean attitude level (3.7) was obtained for a statement “moldy cereals should not be consumed or sold” table 4. this shows that regardless of their knowledge about fungi and mycotoxins, the respondents are consuming and/or selling moldy cereals implying that ignorance about the risk of consuming moldy cereals. this can be interpreted as an important area of intervention to change the attitude teshome and zerihun east african journal of sciences volume 16(2): 171-186 184 of the respondents. the result didn’t show any correlation of mean attitude level with an educational background or occupation (table 5) and did not support the assumption “knowledge might influence awareness as well as attitude, and subsequently, behavioral action of individuals” (mohd azaman et al., 2016; toh and birchenough, 2000). this is an indication of the need for educational training intervention to farmers, agricultural experts, merchants, and another group of the community regarding fungi and their mycotoxins in ethiopia. the previous report also revealed the positive impact of education and training to minimize the risks associated with consuming contaminated foods by fungi and mycotoxins (matumba et al., 2016). analysis of mean management practice level towards reducing fungal infection and mycotoxin contamination based on educational background indicated that the mean practice levels obtained were generally low (1.9). positive correlation of mean management practice level with increased education level (figure 5) reveals the positive impact of increased educational level to alleviate the problem associated with fungal contamination and their mycotoxins. the result of this study was in agreement with the finding of earlier investigators who have reported a positive correlation of practice with a better educational background from different countries (sanlier, 2009; mohd azaman et al., 2016). 5. conclusion the results of this study have revealed that knowledge about fungi and mycotoxin contamination is generally very low among farmers. this signals the need for providing training for farmers at all levels on toxin producing fungi and the danger of their mycotoxins present to humans and animals. making all stakeholders aware about toxin producing fungi and their mycotoxins should be the primary intervention activity. secondly, despite the favorable attitude obtained from the majority of the respondents, all respondents had an established perception that consuming or selling moldy wheat or maize is safe, which is a dangerous belief. consumers have no information on safety the products they consume either. therefore, research institutions, universities, health, and agricultural institutions should work towards changing this established perception, make people aware that there is a danger of consuming aflatoxins with moldy and ill-stored cereal grains. third, the low mean practice level towards reducing fungal invasion and mycotoxin production in the wheat and maize grains suggests the community is at risk of mycotoxin health hazards. the analysis of knowledge, attitude, and practice obtained from teachers and agricultural experts showed higher level of ignorance of the less educated participants of the study than the more educated ones about the danger of consuming moldy cereal grains poses to health. this clearly shows that education is a key tool to minimize the likelihood of consuming or selling moldy cereal grains, which have finally contaminated with mycotoxins. further studies need to be conducted in the future to elucidate the occurrence and consequences of mycotoxins in the various major staple cereal grains consumed in the country for developing management options to minimize health hazards. 6. acknowledgments thanks are due to adama science and technology university for funding the research. 7. references atongbiik, m.a., opoku, n. and amagloh, f.k. 2017. aflatoxin contamination in cereals and legumes to reconsider usage as complementary food ingredients for ghanaian infants: a review. journal of nutrition and intermediary metabolism, 10: 1–7. https://doi.org/10.1016/j.jnim.2017.09.001. birhanu hiruy and emana getu. 2018. insect pests associated to stored maize and their bio rational management options in sub-sahara africa. international journal of academic research and development, 3(1): 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nutrition and development, 18(1): 1318613201. ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(2): 213-224 licensed under a creative commons *corresponding author: tagessetadesse76@gmail.com attribution-noncommercial 4.0 international license. effect of substituting maize with different levels of sweet potato tuber meal on feed intake, feed conversion efficiency, and growth performance of broiler chicks tagesse tadesse1*, mengistu urge2, and negassi ameha2 1college of agriculture and veterinary medicine, jimma university, p.o. box 307, jimma, ethiopia 2college of agriculture and environmental sciences, haramaya university, p.o. box 138, dire dawa, ethiopia abstract background: shortage of conventional energy feedstuff such as maize and significant cost of the ingredients of ration is a major constraint to poultry production in developing countries like ethiopia. in this regard, sweet potato is a locally accessible non-conventional energy feed stuff that can be incorporated into the diets of poultry as an alternative option of energy feed. objective: a study was conducted to evaluate the effect of substituting maize with different levels of sweet potato tuber meal (swptm) on feed intake, feed conversion efficiency, and growth performance of broiler chicks. materials and methods: one hundred ninety-two cobb 500 broiler chick strains with initial weight of 35.64 ± 0.37 (mean ± sd) grams were randomly distributed to four treatments each with three replications in a completely randomized design. the four treatment diets used were rations containing 0% (t1), 15% (t2), 30% (t3), and 45% (t4) level of sweet potato tuber meal to substitute maize. results: the sweet potato tuber meal contained 8.32% crude protein (cp) and 3651 kcal kg dry matter– 1metabolizable energy .the average daily feed intake during the entire experimental period was 71.1, 91, 95.5 and 97.7 gram per chick (sem = 0.77) for t1, t2, t3 and t4 respectively, and higher for t4 as compared to t1, t2 and t3 and lower for t1 as compared to the rest of the treatments (p < 0.05). the body weight gain during the entire experimental period was 31.35, 45.23, 35.91 and 35.39 gram per chick per day (sem = 0.89) for t1, t2, t3 and t4 respectively, and higher for t2 as compared to t1, t3 and t4. the feed conversion ratios during the entire period were 2.21, 1.98, 2.60 and 2.7 (sem = 0.05) for t1, t2, t3 and t4, respectively and better for t2 as compared to t1, t3 and t4. conclusion: based on the results of the experiment, it can be concluded that sweet potato tuber meal at 15% levels in broilers ration diet enhanced feed intake and growth performance of broiler chicks. based on the feed intake and growth performance of the broiler chicks, 15% graded level of swptm for maize in the diet is recommended according to the current study. keywords: body weight gain; cobb500; feed conversion ratio; root crop; sun dried 1. introduction chicken meat and eggs have been recommended to bridge the protein gap more than other species of livestock because of short generation interval, high rate of productivity, quicker turnover rate, higher feed efficiency, and low labor and land requirements (ojedapo et al., 2008). feed cost is frequently ensnared in the significant expense of chicken items. it is assessed to address the greater part of the absolute expense of chicken production under intensive condition (wilson and beyer, 2000). accordingly, feed costs account for up to 70% of total costs in typical livestock production systems and up to 69% in intensive poultry production systems (donohue and cunningham, 2009). in developing nations, feed shortage and significant expense of the ingredients of rations are a major constraint to poultry production. maize, which typically forms the greater part tagesse et al. east african journal of sciences volume 16(2): 213-224 214 of such diets, has numerous different uses and may not be effectively accessible for poultry production in the future. maize is progressively being used for human food and other industrial purposes including biofuel production and alcoholic beverages (potter and hotchkiss, 1995 and dei, 2017). moreover, production of maize in many tropical countries has fallen relative to the rising interest in the grain because of continuous frequent drought, flood, and insect invasion that are influencing some maize-delivering regions. consequently, relying solely on maize as the sole significant wellspring of dietary energy for the poultry business might be unsafe and an option is required (agwunobi, 1999). most of the developing countries have been fighting to supply satisfactory feed to their livestock, because of insufficient production of conventional ingredients for livestock feeding. humans and livestock compete for the insufficient amounts of concentrated feedstuffs they produce yearly. subsequently, the shortage of feed resources regularly forces a major challenge in livestock production in these countries (aregheore, 2000). a serious problem in ethiopia’s livestock production system has been distinguished as a lack of feed in both quantity and quality (adugna tolera, 2009). the normal increasing expense of maize because of decreased production and its variable use require research to discover less expensive and locally accessible nonconventional energy feed stuff such as sweet potato (ipomoea batatas lam). substitution of some portion of conventional corn diet with a cheaper option feedstuff like sweet potato meal is an alternative option. ingredient substitution in a conventional compound ration requires no only the assessment of the chickens’ performance and carcass qualities but also the overall acceptability of the ingredient by the chickens (poste, 1990). in this respect, sweet potato as the new ingredient of the ration ought to have the option to fill in for corn completely or partially and not oppositely influence the productivity of chickens. that is, it must not lessen feed intake and efficiency, growth, dressing percentage, and should not adversely influence survival and should produce a product of the same or superior quality (ojewola et al., 2006). the findings of onyekwere et al. (2008) revealed that including 20% of sweet potato root meal to the whole ration had no negative impact on broiler starter phase. similarly, inclusion of 38.73% dietary sweet potato meal will enhance acceptable growth performance for japanese quail (edache et al., 2009). sweet potato tuber is fit for use as feed in the poultry industry. in addition, it has low anti-nutritional factors, low fibre, and high nitrogen free extract and is highly palatable (ravindran and blair, 1991 and afolayan, 2010). it can be incorporated into the diets of monogastric animals as a source of energy without any detrimental effect on their wellbeing and performance, thereby reducing the expense of feeding. its main nutritional importance has been its starch content. however, sweet potato can also be a source of other nutritionally significant dietary factors like vitamin a, ascorbic corrosive, thiamin, riboflavin and niacin (dominguez, 1990). the few accessible reports agree that sweet potato can be incorporated into diets of chickens yet should not be made the sole source of energy (tewe, 1991). the findings of onyekwere et al. (2008) revealed that adding 20% of sweet potato root meal to the diet had no negative impact on broiler starter phase. likewise, inclusion of 38.73% dietary sweet potato meal will enhance acceptable growth performance for japanese quail (edache et al., 2009). the potential of dried leaves of sweet potato supplementation offers enough energy and protein for optimum growth and feed conversion efficiency when used in finisher chicks ration up to a level of 10–15% of the ration and leads to significant weight gains (tsega wude and berhan tamir, 2009). melesse aberra et al. (2017) reported that partially replacing cooked soybean seed with sweet potato leaf meal in broiler diets and can be a feasible alternative in smallholder chicken production systems. therefore, an alternative to cereals in livestock feeds might be the only immediate solution (scott, 1995). sweet potato roots are a good source of energy for poultry (ravindran et al., 1995). several studies have evaluated the use of possible alternative feed ingredients; however, more widespread feed trials have to be done in order to meet the requirements set forth by the national research council. various experiments have been conducted on the topic of using sweet potato vines and leaves for production chickens. they have been included in diets as a source of protein and improved the yellowish pigmentation of skins, growth rate, feed intake and feed conversion efficiency of broiler chicks (woolfe, 1992; farrell et al., 2000 and tsega wude and berhan tamir, 2009). besides, there have been some accessible studies done on use of partially cooked meal of sweet potato in the diet. the inclusion of partially cooked sweet potato tuber meal did not affect the performance of chickens’ in terms of daily body weight gain and feed conversion ratio (adeduwura et al., 2012). this experiment was aimed to evaluate a raw sweet potato tuber without peeling the skin tagesse et al. effect of substituting maize with sweet potato tuber on broiler chicks 215 as a source of energy feed ingredient to substitute maize in chicks’ diet. the research was, therefore, conducted to investigate the effect of substituting maize with different levels of sun-dried sweet potato tuber meal on feed intake, feed conversion efficiency, and growth performance of broiler chicks. 2. materials and methods 2.1. description of the study area the experiment was conducted at haramaya university’s poultry farm on the main campus. the university is located at 42°3’ e longitude, 9°26’ n latitude, and at an altitude of about 2006 meters above sea level. the campus of the university is about 505 km far from addis ababa, the capital city of ethiopia, in the easterly direction. the mean annual rainfall of the area amounts to 780 mm and the average minimum and maximum temperatures are 8 and 24 °c, respectively (samuel sahile, 2008). 2.2. feed ingredients and experimental rations the feed ingredients used in the formulation of the different experimental rations of the study were maize grain, raw sun-dried sweet potato tuber meal, wheat short, noug seed cake, soybean meal, vitamin premix, methionine, lysine, salt and limestone. sweet potato tuber was purchased from haramaya district farmers. whole fresh sweet potato tuber without removing skin was cleaned, washed and cut in to small pieces, then spread on plat form (canvas) under the sun and dried for one week. the dried sweet potato tuber slice was hammer-milled with the sieve size 5mm and stored until incorporation into the diets. the sun dried sweet potato tuber meal was mixed with the other feed ingredients depending on the substitution level for maize in each treatment. the treatment rations were formulated to be isocaloric and isonitrogenous to meet the nutrient requirements of starter and finisher broilers (leeson and summer, 2005). treatment rations were formulated by substituting raw sun-dried sweet potato tuber meal for maize at a graded level of 0, 15%, 30%, and 45%. rations were formulated to contain approximately 22% and 20% cp and 3100 kcal/kg and 3200 kcal/kg me for starter and finisher phases, respectively (nrc, 1994). the starter phase was until three weeks of age. the finisher phase covered the period from three weeks onwards up to sixth weeks of age and the respective rations were fed accordingly. the starter and finisher diets were formulated separately as indicated in tables 1 and 2, respectively. table 1. percentage proportion of ingredients used in formulating starter ration. ingredient (%) treatments t1 t2 t3 t4 swptm 0 15 30 45 maize 45 30 15 0 ws 7.4 8.4 6.4 7 sbm 30 31 31 31 nsc 15 13 15 14.4 limestone 1 1 1 1 vp 0.8 0.8 0.8 0.8 lysine 0.1 0.1 0.1 0.1 methionine 0.2 0.2 0.2 0.2 salt 0.5 0.5 0.5 0.5 total 100 100 100 100 note: swptm = sweet potato tuber meal; ws = wheat short; sbm = soybean meal; nsc = noug seed cake; vp = vitamin premix; t1 = 0% of maize substituted by sweet potato tuber meal; t2 = 15% of maize substituted by sweet potato tuber meal; t3 = 30% of maize substituted by sweet potato tuber meal; and t4 = 45% of maize substituted by sweet potato tuber meal. tagesse et al. east african journal of sciences volume 16(2): 213-224 216 table 2. percentage proportion of ingredients used in formulating finisher ration. ingredients (%) treatments t1 t2 t3 t4 swptm 0 15 30 45 maize 45 30 15 0 ws 16.4 17 14.4 15.4 sbm 26 25 25 25 nsc 10 10.4 13 12 limestone 1 1 1 1 vp 0.8 0.8 0.8 0.8 lysine 0.1 0.1 0.1 0.1 methionine 0.2 0.2 0.2 0.2 salt 0.5 0.5 0.5 0.5 total 100 100 100 100 note: swptm = sweet potato tuber meal; ws = wheat short; sbm = soybean meal; nsc = noug seed cake; vp = vitamin premix; t1 = 0% of maize substituted by sweet potato tuber meal; t2 = 15% of maize substituted by sweet potato tuber meal; t3 = 30% of maize substituted by sweet potato tuber meal; and t4 = 45% of maize substituted by sweet potato tuber meal. 2.3. treatments and experimental design the treatments consisted of one hundred ninety-two cobb 500 broiler chick strains with initial weight of 35.64 ± 0.37 (mean ± sd) grams. these chicks were randomly distributed to four treatments. the four treatment diets used were rations containing 0% (t1), 15% (t2), 30% (t3), and 45% (t4) level of sweet potato tuber meal to substitute maize. the experiments were laid out as a completely randomized design (crd) and replicated three times per treatment. twelve pens were used for the one hundred ninety-two day old chicks and the chicks were randomly assigned to each pen (table 3). table 3. experimental treatments. treatments number of replication starter phase finisher phase chicks/replication chicks/replication r1 r2 r3 r1 r2 r3 t1 3 16 16 16 15 14 14 t2 3 16 16 16 13 15 15 t3 3 16 16 16 15 15 14 t4 3 16 16 16 14 16 13 note: r1, r2 and r3 refer to replication one, two and three, respectively; t1 = 0% of maize substituted by sweet potato tuber; t2 = 15% of maize substituted by sweet potato tuber; t3 = 30% of maize substituted by sweet potato tuber; and t4 = 45% of maize substituted by sweet potato tuber meal. 2.4. management of experimental chicks the experimental pens were cleaned and disinfected two weeks before the arrival of the chicks. the pens were washed down with water and sprayed with a commercial disinfectant labeled for use in the poultry farm. the feeding and drinking troughs were properly cleaned, dried and disinfected before chicks’ arrival. one hundred ninety-two cobb500 chicks were purchased from debre zeit poultry commercial farm. for these chicks, 12 pens were used and their floors were covered with wood shaving. each pen was also equipped with a 250-watt heat bulb. the chicks were randomly grouped into 12 pens (16 chicks per replication) and allotted to the four treatments in three replications. the chicks were fed ad libitum in groups in plastic trays throughout the experimental period. water was given by small round waterers for the first three weeks followed by normal round waterers for the remaining time of the trial period and the experiment took a total of 45 days. all health precautions were taken and appropriate disease control measures were carefully followed throughout the study period. tagesse et al. effect of substituting maize with sweet potato tuber on broiler chicks 217 2.5. chemical analysis of feed representative samples were taken from each of the feed ingredients used in the experiment and analyzed before formulating the actual treatment rations. based on the chemical composition of the ingredients, ration formulation was done for each treatment. samples of chemical analysis of the experimental diets containing different proportions of sweet potato tubers was done from composite sample at the end of the experiment. samples were analyzed according to weende or proximate analysis method (aoac, 1990). chemical analyses of experimental feeds were carried out for dry matter (dm), crude protein (cp), ether extract (ee), crude fiber (cf) and ash in animal nutrition laboratory of the haramaya university. nitrogen (n) content was determined by kjeldahl procedure and crude protein (cp) was calculated as n x 6.25. calcium and phosphorus contents were determined by atomic absorption spectrophotometer. metabolisable energy (me) of the experimental diets was determined by an indirect method according to the formula given by wiseman (1987) as follows: me (kcal/kgdm) = 3951 + 54.4ee – 88.7cf – 40.8ash 2.6. parameters evaluated and data collection procedure 2.6.1. feed intake the feed was weighed every day to determine the average feed intake per chick for the different treatment groups. feed intake was calculated as the difference between offered and leftover feed. 2.6.2. body weight gain (bwg) and feed conversion ratio (fcr) the chicks were weighed at the beginning of the experiment and every week to determine the average weight gain per chick for the different treatment groups. the average daily weight gain (adg) was determined by dividing the average body weight gain by the number of experimental days. feed conversion ratio (fcr) was calculated as the ratio of average feed intake divided by average body weight gain (g). 2.7. management of data and statistical analysis the experiment data were subjected to analysis of variance (anova) using the general linear model (glm) procedure of sas (2009) version 9.2. when the analysis of variance revealed the existence of significant differences, the differences among treatment means were compared using least significant difference (lsd) test at p < 0.05. the model used for data analysis was: yij = μ+ti + eij where, yij = an observation (experimental unit); μ = overall mean; ti = treatment effect (i = 1-4); and eij = random error term. 3. results and discussion 3.1. chemical composition of experimental diets laboratory results showed that the energy contents of sweet potato tuber meal (swptm) and maize were 3651 and 3650 kcal kg–1, respectively (table 4). the result revealed that the energy contents of both maize and sweet potato tubers were almost similar. this would make sweet tuber an effective energy feed with the potential to be used as a substitute for maize in broiler ration. this result is in agreement with the finding of ravindran and blair (1991) who reported that swptm contains energy that is comparable to the energy contained by maize in broiler diets. the crude protein content of swptm was 8.32%, which is higher than the crude protein (cp) content of about 5.07% found by muragun et al. (2012) in sweet potato tuber. this variability in the content of crude protein in sweet potato tuber could be attributed to differences in the varieties of sweet potato, climatic and geological condition of area from where the sweet potato tubers originated. the laboratory dm percentage of sweet potato tuber was 95.4%, which is similar with the finding of bartlett and beckford (2015) who found 94.7% dm in sweet potato tuber. the fiber content of sweet potato tuber was 1.81%, which is almost similar with the finding of apata and babalola (2012) who noted 1.53% cf in sweet potato tuber. tagesse et al. east african journal of sciences volume 16(2): 213-224 218 table 4. chemical composition of feed ingredients. chemical composition ingredients swptm maize ws sbm nsc dm% 95.4 90.2 89.8 94.0 93.0 cp%dm 8.32 9.0 15.0 40.6 32.5 ee%dm 0.82 5.76 3.25 8.2 5.1 cf%dm 1.81 5.45 7.29 5.9 17.9 ash%dm 4.52 3.2 4.95 7.6 7.8 ca% dm 0.27 0.06 0.65 0.3 0.46 p%dm 0.17 0.32 0.93 0.7 1.1 me(kcal/kg dm) 3651 3650 3279 3564 2323 note: swptm = sweet potato tuber meal; ws = wheat short; sbm = soybean meal; nsc = noug seed cake; dm = dry mater; ee = ether extract; cf = crude fiber; cp = crude protein = phosphorus; ca = calcium; and me = metabolizable energy. the metabolizable energy (me) and cp contents of treatment rations within each phase were similar (table 5), as the treatment rations were formulated to be isocaloric and isonitrogenous. the metabolizable energy values of the diets were not far from the recommended value of 3100 and 3200 kcal kg–1 for the starter and finisher phases (nrc, 1994) of broiler chickens, respectively. table 5. chemical composition of experimental rations (% dm). treatments dm% cp (%) ee (%) cf (%) ash (%) ca (%) p (%) me (kcal kg–1 dm) starter diet t1 92.7 22.2 3.1 6.0 10.5 0.8 0.5 3159 t2 92.5 22.1 3.1 6.1 10.2 0.8 0.6 3162 t3 92.6 22.3 3.0 5.9 10.4 0.9 0.7 3166 t4 92.7 22.1 3.0 5.9 10.3 0.9 0.7 3170 finisher diet t1 91.7 20.3 3.2 5.8 8.0 0.8 0.6 3284 t2 91.6 20.1 3 5.7 8.0 0.7 0.6 3282 t3 91.7 20.4 3.8 5.7 9.2 0.8 0.7 3276 t4 91.9 20.1 4.0 6.0 9.0 0.9 0.8 3280 note: swpt = sweet potato tuber; ws = wheat short; sbm = soybean meal; nsc = noug seed cake; dm = dry mater; ee = ether extract; cf = crude fiber; cp = crude protein; p = phosphorus; ca = calcium; me = metabolizable energy; t = 0% of maize substituted by sweet potato tuber meal; t2 = 15% of maize substituted by sweet potato tuber meal; t3 = 30% of maize substituted by sweet potato tuber meal; and t4 = 45% of maize substituted by sweet potato tuber meal. 3.2. feed intake the results showed that the average daily and total feed intake during the starter and finisher phases as well as for the whole experimental period was affected (p < 0.05) by the treatments (table 6). accordingly, substitution of maize by different levels of sweet potato tuber meal improved feed intake as compared to the control group during the starter phase. feed intake during the finisher phase increased with the increasing level of sweet potato tuber meal in the diet. however, feed intake during the entire experiment period was higher in t3 and t4 as compared to t1 and t2, and t2 has higher feed intake than t1 showing that feed intake was increased as level of inclusion of swptm increased. this indicates that the sweetness of swptm played a positive role in improving intake of diets containing swptm, considering the fact that the diet without swptm inclusion was the least consumed during all phases. the increment in feed intake might also be due to the difference in the breed of chickens used, the difference in the varieties of sweet potato, and the various preparation techniques of the swptm. this result is in agreement with the findings of afolayan et al. (2012) who reported a significant difference in feed intake within groups of chickens fed different substitution levels of swptm meal for maize in the broiler ration. bartlett and beckford (2015) did not note significant differences in total feed intake and daily feed intake in chicks fed on rations containing different tagesse et al. effect of substituting maize with sweet potato tuber on broiler chicks 219 substitution levels of sweet potato tuber meal for maize indicating sweet potato meal did not affect feed intake. significantly higher intake in chicks fed on ration containing swptm in the present study compared to that reported in some literature could be an attribute of the difference in breeds of chickens used, the difference in the varieties of sweet potato, and the different preparation methods of the swptm. table 6. the effect of feeding different substitution levels of sweet potato tuber meal for maize on feed intake of broilers during the starter and finisher phases as well as the entire growth period. parameters treatments t1 t2 t3 t4 sem p-value starter phase total feed intake (g) 831.7b 1014.8a 1069.2a 1042.9a 45.66 0.0234 daily feed intake (g/chick/day) 39.6b 48.3a 50.9a 49.6a 2.17 0.0234 finisher phase total feed intake (g) 2296.3d 2999c 3133.3b 3258.9a 30.00 <0.0001 daily feed intake (g/chick/day) 99.8d 130.4c 136.2b 141.7a 1.30 <0.0001 entire period total feed intake (g) 3128c 4004.8b 4202.5a 4301.8a 33.93 <0.0001 daily feed intake (g/chick/day) 71.1c 91b 95.5a 97.7a 0.77 <0.0001 note: means within a row with different letters are significantly different at p < 0.05. sem = standard error of the mean; t1 = 0% of maize substituted by sweet potato tuber meal; t2 = 15% of maize substituted by sweet potato tuber meal; t3 = 30% of maize substituted by sweet potato tuber meal; and t4 = 45% of maize substituted by sweet potato tuber meal. 3.3. body weight gain body weight change and average daily weight gain was affected significantly (p < 0.05) by the treatments. analysis of variance revealed significantly higher (p < 0.05) weight gain of chicks subjected to treatment two (t2) as compared to those subjected to the other treatments during the starter and finisher phases as well as during the entire period of the experiment. in finisher and entire experimental period, chicks in treatment one (t1) gained lower weight compared to treatment three and treatment four. the lower growth of chicks in treatment one (t1) might be related to the relatively lower feed intake. reduction in the rate of growth of chicks subjected to treatment three (t3) and treatment four (t4) rations during starter and finisher phases as well as during the entire experimental period as compared to treatment two (t2) might be related to the increase in wet droppings resulting in a gradual decrease in the live weight gain. this wet dropping may indicate the laxative effect of sweet potato tuber in higher rate of replacement (aguwobi, 1999). this laxative effect of sweet potato tuber meal may have affected feed efficiency, body weight gains and greatly reduced the abdominal fat of chicks. this could be due to the presence of some antinutritional factor (agowubi, 1999 and maphosa et al., 2003) in sweet potato tuber meal that may have affected the utilization of the diet, rendering it more difficult for the chicks to convert feed into flesh and so to convert enough to deposit as fat. according to agwunobi (1999), there was an increase in wet droppings, and a gradual decrease in live body weight gain with increased level of swptm. similarly, ayuk and essien (2009) reported that as the level of sweet potato root meal increased, body weight and daily body weight gain decreased as compared to lower level of substitution, although it was still better than the control group. tagesse et al. east african journal of sciences volume 16(2): 213-224 220 table 7. the effect of feeding different substitution levels of sweet potato tuber meal for maize on body weight change of broilers during the starter and finisher phases as well as the entire growth period. parameters treatments t1 t2 t3 t4 sem p-value starter phase ibws (g) 35.86 35.83 35.83 35.40 0.20 0.2942 fbws (g) 419.21b 448.63a 414.30b 394.86b 8.84 0.0167 tbwgs (g/chick) 383.35b 412.80a 378.83b 359.46b 8.96 0.0188 dbwgs (g/chick/day) 18.25b 19.65a 18.03b 17.11b 0.42 0.0188 finisher phase fbwf (g) 1415.17c 2025.76a 1615.63b 1592.93b 39.41 <0.0001 tbwgf (g/chick) 1031.82c 1612.96a 1236.80b 1233.46b 37.49 <0.0001 dbwdf (g/chick/day) 44.86c 70.13a 53.77b 53.63b 1.63 <0.0001 entire period fbwe (g) 1415.17c 2025.76a 1615.63b 1592.93b 39.41 <0.0001 tbwge (g/chick) 1379.30c 1989.93a 1580.16b 1557.53b 39.42 <0.0001 dbwge (g/chick/day) 31.35c 45.23a 35.91b 35.39b 0.89 <0.0001 note: means within a row with different letters are significantly different at p < 0.05. ibws = initial body weight in starter phase; fbwf = final body weight in starter phase; tbwgs = total body weight in starter phase; dbwgs = daily body weight gain in starter phase; ibwf = initial body weight in finisher phase; fbwf = final body weight in finisher phase; tbwgf = total body weight gain in finisher phase; dbwgf = daily body weight gain in finisher phase; ibwe = initial body weight in entire period; fbwe = final body weight in entire period; tbwge = total body weight gain in entire period; dbwge = daily body weight gain in entire period; and sem = standard error of the mean. 3.4. feed conversion ratio (fcr) there was a significant difference (p < 0.05) in feed conversion ratio (fcr) among the treatments. chicks subjected to treatment one (t1) ration possessed the lower (p < 0.05) fcr than those subjected to treatment three (t3) and treatment four (t4) during the starter phase. however, no statistically significant difference was detected between chicks subjected to treatment one (t1) and treatment two (t2) as well as among those subjected to treatment two (t2), treatment three (t3), and treatment four (t4) during this phase. during the finisher phase and the entire period of the experiment, fcr of the groups that consumed feed in the treatment one (t1) and treatment two (t2) were significantly lower (p < 0.05) than those that consumed feed in the treatment three (t3) and treatment four (t4) ps and treatment. chicks subjected to treatment two (t2) displayed lower fcr than those subjected treatment one (t1), treatment three (t3) and treatment four (t4) during the entire period of the experiment. the results of this study showed that higher substitution level of swptm did not improve feed conversion ratio, and treatment two compared to treatment three and treatment four had better fcr indicating 15% sweet potato tuber meal (treatment two) inclusion as a substitution for maize is more efficient than a higher level supplementation. that was a lower feed conversion ratio for treatment two could be ascribed to better efficiency of feed utilization than for the other treatments. this finding is in agreement with that recorded by afolayan et al. (2012) who reported that inclusion of sweet potato tuber meal depressed feed use efficiency resulting in decreased body gain weight. tagesse et al. effect of substituting maize with sweet potato tuber on broiler chicks 221 table 8. the effect of feeding different substitution levels of sweet potato tuber meal for maize on feed conversion ratio (fcr) of broilers during the starter and finisher phases as well as the entire growth period. parameters treatments t1 t2 t3 t4 sem p-value fcrs 2.16b 2.45ab 2.83a 2.89a 0.14 0.0206 fcrf 2.22b 1.85c 2.53a 2.64a 0.06 <0.0001 fcre 2.26b 2.01c 2.55a 2.76a 0.05 <0.0001 note: means within a row with different letters are significantly different at p < 0.05. fcrs = feed conversion ratio in starter phase, fcrf = feed conversion ratio in finisher phase, fcre = feed conversion ratio in entire period, sem = standard error of the mean, t1 = 0% of maize substituted by sweet potato tuber meal; t2 = 15% of maize substituted by sweet potato tuber meal; t3 = 30% of maize substituted by sweet potato tuber meal; and t4 = 45% of maize substituted by sweet potato tuber meal. 4. conclusions and recommendations the results of this study have demonstrated that significant differences in feed intake, weight gain and feed conversion ratio of chicks subjected to different feed treatments of maize and sweet potato as starter and finisher phases and during the entire experiment periods. substitution of swptm for maize increased daily feed intake of the broiler chicks compared to the control. weight change and daily weight gain was affected by the treatments. significantly, higher weight gain was recorded for treatment two (t2) as compared to the other treatments during the starter and finisher phases as well as during the entire experimental periods. generally, the substitution of sweet potato tuber meal improved the feed intake and the growth performance of the chicks. thus, 15% sweet potato tuber meal (swptm) substitution level for maize in broiler 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(eds.). expert http://dx.doi.org/10.5713/ajas.15.0642 tagesse et al. effect of substituting maize with sweet potato tuber on broiler chicks 223 consultation roots, tubers, plantains and bananas in animal feeding. cali, columbia. tsega wude and tamir berhan. 2009. the effect of increasing levels of dried leaves of sweet potato (ipomoea batatas) on dry matter intake and body weight gain performance of broiler finisher chickens. livestock research for rural development, 21(12): available at http://www.lrrd.org/lrrd21/12/wude21208.htm. wilson, k.j. and beyer, r.s. 2000. poultry nutrition information for the small flock. kansas state university agricultural experiment station and cooperative extension service. wiseman, j., editor. 1987. feeding of non-ruminant animals. 1st edition. butterworth-heinemann, london. pp. 228. woolfe, j.a. 1992. sweet potato: an untapped food resource. cambridge university press, england. pp. 643. tagesse et al. east african journal of sciences volume 16(2): 213-224 224 ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(2): 199-212 licensed under a creative commons *corresponding author: mulatudst6@gmail.com attribution-noncommercial 4.0 international license. in vitro evaluation of the probiotic potential of lactic acid bacterial strains retrieved from raw and traditionally fermented cow milk mulatu workie1*, betemariam kebede1, tefera tadesse1, daniel yimer1, tirsit tibebu1, sewunet abera1, adaba tilahun1, melaku alemu2, tadessa daba1, adane eshetu1, asab alemneh1, birhanu babiye1, gudeta dida1, and tariku abena1 1holetta national agricultural biotechnology research centre, ethiopian institute of agricultural research (eiar), p.o. box 2003, addis ababa, ethiopia 2ethiopian agricultural research council secretariat, addis ababa, ethiopia abstract background: probiotics are live bacteria found mostly in milk and milk products that have been shown to improve intestinal microflora composition, treat lactose intolerance, prevent cancer, allergies, hepatic illness, and lower cholesterol. ethiopians consume a lot of dairy and dairy products. however, little is known about the starter and probiotic properties of the lactic acid bacteria consumed with these items in the country. objective: the objective of this research was to identify and evaluate the probiotic functioning of lactic acid bacteria from raw and traditional fermented cow milk. materials and methods: lactic acid bacteria were isolated from raw milk and yoghurt samples collected from ethiopia (holetta, adama and bishoftu). three hundred and fifty colonies exhibiting the characteristic features of lactic acid bacteria were used for gastric and bile salt tolerance tests. results: from among the 27 isolates, 10 (37%) showed a significant tolerance to the various ranges of gastric ph and bile salt concentrations (p ≤ 0.05). the highest gastric acid tolerance was observed for the isolate ad6 (od = 1.352 ± 0.063) at the gastric ph of 4.0 at 24th hours of incubation followed for the isolate nz26 (od = 0.870 ± 0.058) at the same gastric ph and incubation hour. isolate g25 (od = 0.733 ± 0.103) was able to tolerate 2% (w/v) of bile salt at 2 h of incubation time. four isolates dz3 (od = 0.578±0.103), g37 (od = 0.657 ± 0.046), ad22 (od = 0.683 ± 0.072) and nz3 (od = 0.694 ± 0.070) showed a significance tolerance at 1% (w/v) of bile salt concentration at the 24th hours of incubation. conclusion: the findings revealed that naturally occurring lactic acid bacteria isolated from dairy products have the potential for probiotic applications in the dairy industry in the country.this could pave the way for exploiting the isolates at industrial level and could transform traditional dairy processing with probiotic function in ethiopia. keywords: bile salt; dairy products; gastric acid; lactic acid bacterial; probiotic potential 1. introduction probiotics, according to the definitions given by ejtahed et al. (2011) are live microorganisms that provide health benefits on the host. they are known to improve the composition of intestinal micro flora, relieve lactose intolerance, prevent cancer, allergies, hepatic disease and facilitate cholesterol (yusuf et al., 2018). lactic acid bacteria are found in various traditional fermented foods such as dairy products. lactic acid bacteria are currently the subject of extensive research due to their involvement in most traditional fermented foods and their potential to produce antimicrobial metabolites that enhance the shelf life of food products (yeshambel et al., 2021). in addition, the consumption of probiotics has been associated with enhanced immune response, reduced onset of enter pathogenic bacteria in the gut and diarrhoea (reid, 1999). previously, scientific investigations have supported a role for probiotics as a part of a healthy diet for humans and animals and may be an avenue to provide a safe and cost effective barrier mailto:mulatudst6@gmail.com mulatu et al. east african journal of sciences volume 16(2): 199-212 200 against microbial infections (parvez et al., 2006). dairy and food industries use metabolites of probiotic lactic acid bacterial for natural preservatives and flavour enhancers (reid, 1999). lactic acid bacteria gained the reputation for being the main probiotic microbes. these beneficial microbes belong to a diverse bacterial group consisting of 11 genera. they are gram-positive, non-spore-forming cocci or rods able to produce lactic acid as a by-product. historically, lactic acid bacteria are considered gras (generally regarded as safe) microbes and especially members of the genus lactobacillus, lactococcus and streptococcus are widely used in the food industry. nowadays, various species of lactobacillus have been used in food products as probiotic functioning organisms. probiotic strains are selected for potential application on the basis of particular physiological and functional properties (sanders et al., 1999). probiotics are living, health-promoting microorganisms that are incorporated into various kinds of foods and the probiotic bacterial strains are generally provided with food system and then consumed orally, their passages set up from the mouth to the lower intestinal lumen, and thus the strains are required to overcome different stress conditions such as low-ph and bile in the gastrointestinal tract for survival and the beneficial effect (hoque et al., 2010). according to sivapalasingam et al. (2004) the problem of food-borne diseases is multifactorial, and their prevention and control require multidisciplinary approaches that involve human beneficial live microbes (probiotics) in order to combat these pathogens and their associated health risks. several in vitro studies indicated that probiotic lactic acid bacteria (tesfaye et al., 2011) inhibit the growth of food-borne pathogenic microbes. the consumption of a large number of probiotic live microorganisms together with a food fundamentally promotes the health of the consumers. in ethiopia, a considerable portion of milk is consumed in a fermented state as “ergo”. the fermentation is takes place naturally, without the use of defined starter culture to initiate the fermentation process and this is made only through the proliferation of normal microbial flora in the milk. in addition, little is known regarding the starter and the probiotic functions the microbes used in this regard. it does not have any definite temperature and duration of incubation. the development of microorganisms during ergo fermentation showed variations in various parameters. despite limitations with dose and viability of probiotic strains, a lack of industry standardization, and potential safety concerns, according to parvez et al., 2006, there is clearly substantial promise for the benefits of probiotics across a wide range of clinical disorders. basic research will continue to identify and characterize existing probiotic strains, as well as identify strain-specific outcomes, define the best dose for specific outcomes, and test their stability during processing and digestion. many people worked on isolating and screening antibacterial-producing lactic acid bacteria from traditionally fermented foods (akalu et al., 2017). tesfaye et al., 2011 discovered that lactic acid bacterial strains, either as pure or defined mixed cultures, exhibit antagonistic effects against some food-borne pathogens during the fermentation and storage of fermented milk. however, there is currently a scarcity of studies on probiotic lactic acid bacteria characterisation. the majority of ethiopia's traditionally fermented items are ingested without further heat processing, making them suitable vehicles for transporting probiotic bacteria into the human gastrointestinal tract.despite the fact that there has been a lot of study done on probiotics, there is still a need to find new strains because probiotic qualities are strain-specific. given the benefits of probiotics on child growth, using readily available and less expensive fermented food products as a vehicle for probiotics could play a significant role in improving nutrition, treating enteric infections, and promoting compensatory growth in children in developing countries via these various mechanisms. before promoting fermented foods in supplemental feeding in underdeveloped nations, more research is needed regarding consumer confidence, acceptance of fermented goods as a source of probiotics, and safety issues (sleator, 2010).the research hypothesis is that lactic acid bacteria with high probiotic activities can be found in dairy products such as raw milk and yogurt.generally, dairy products are considered primary food sources for lactic acid bacteria probiotics. fermented cow milks are consumed in different regions of the world. the presence of high counts of lactic acid bacteria in dairy products as beneficial micro biota indicates a source for explorations of biological materials of considerable health importance and vast applications in the dairy industry. although researchers from other countries have screened and characterized lactic acid bacteria probiotic strains from various dairy products and food hence, in the present study, we aimed at isolating, characterizing and evaluating the probiotic functioning potential of lab from indigenous ethiopian dairy products. mulatu et al. probiotic potential of lactic acid bacterial strains 201 2. material and methods 2.1. chemicals and media chemicals and reagents used in this study were de man, rogosa and sharpe (mrs, oxoid ltd., basingstoke, england) agar for lactobacillus and m17 broth and agar powder for lactococcus isolation (hi media, mumbai, india). all experiments were conducted at the holetta national agricultural biotechnology research centre, national microbial biotechnology research laboratory, ethiopia. 2.2. study design lactating dairy cattle were the study animals that were managed in a semi-intensive way. isolation and characterization of lactic acid bacteria was done from raw milk and yoghurt obtained from lactating dairy cows in holetta, adama and bishoftu towns in central ethiopia. 2.3. sample collection and isolation of lactic acid bacterial strains a total of twenty (20) milk samples (1000 ml) were collected from lactataing dairy cows from holetta, adama and bishoftu) towns using sterile bottles. the milk samples were kept at 4oc before isolation. the samples were transported to the national agricultural biotechnology research centre, holetta national microbial biotechnology research laboratory. after 3–5 days of complete fermentation, the raw milk samples were serially diluted (1:10) using sterile saline [0.85% nacl (w/v)]. the fermented samples were ready for serial dilution with no further fermentation needed. hundred microliters (100μl) sampled from the serial dilutions (10–4–10–7) were spread on to de man, rogosa and sharpe (mrs) and m17 agar media using glass road. the plates were incubated at 37 oc for 24– 72 h anaerobically. finally, colonies that exhibited the characteristics of lactic acid morphology (rod shaped cell, on sporulating, small and white colonies) were picked, and maintained as mrs and m17 broth for further study (hoque et al., 2010). 2.4. preservation of cultures of pure lactic acid bacteria isolates tubes containing 5–10 ml of mrs or m17 broth were inoculated heavily with pure, fresh overnight cultures of the isolates (4% v/v) stored at 4–6 °c in a refrigerator) for short term preservation. for long period maintenance of isolates, 10% of skim milk powder was prepared and autoclaved at 121 oc for 5 minutes. fresh lactic acid bacterial cultures from broth were inoculated into eppendorf tubes containing 1 to 2 ml of skim milk. the tube was incubated at 37oc for 18 to 24 h. cells from mrs and m17 broth were separated by centrifuge at 10000 rpm for 10 minutes. then, the cell-free the supernatant was discarded and the pellets were suspended in 10% glycerol, then the tube was kept at –20 oc for further use. 2.5. preliminary screening of lactic acid bacteria mass selection of lab using deep well micro titration plates bacterial isolates were refreshed in mrs broth at 37 oc for 18 h and washed three times at 6000/5000 rpm for 10 minutes using normal saline solution (0.85% nacl) to get rid of the broth media traces. the turbidity of bacterial suspension was adjusted to optical density (od) of 0.1 to 0.5 using a spectrophotometer at 630 nm. ninety-six well microtiter plates were filled with 990 μl of mrs broth supplemented with bromocresol purple (0.04 g/1000 ml) and were inoculated with 10 μl of the standardized lab cultures. culture-free wells served as a negative control. finally, the plates were incubated at 37 oc for 18 to 24 h and absorbance was read at 630 nm and the formation of a yellow colour (indicating a positive result for fermentation or acid reduction efficiency of the strains) was examined visually. 2.6. gastric acid tolerance test the ninety-six deep well microtiter plate method was used for evaluating the stomach gastric acid tolerance efficacy of the isolates according the method mentioned in (suree et al., 2012) de man, rogosa and sharpe broth was used. the selected isolates were incubated in microtiter plates containing different ph values (2, 3 and 4) and samples were taken at 0, 2nd, 4th and 24th hour of incubation. the optical density (od) of the broth was read at 630 nm and the results of the reading recorded. 2.7. bile salt tolerance test the isolates were grown in de man, rogosa and sharpe broth supplemented with 0.3%, 1%, 1.5% and 2% bile oxgall with the ph adjusted to 7 and 8 (john and alicia, 2011; liong and shah, 2005). the optical density (od) of the incubated samples were read at 630 nm prior to 0 h, 2 h, 4 h and 24h of incubation against blank mrs with and without bile oxgall (gilliland and walker,1990; liong, 2006). mulatu et al. east african journal of sciences volume 16(2): 199-212 202 2.8. data analysis the data were analysed using sas statistical software packaged version 9.2 for windows. results were presented as mean ± sd and one-way anova was performed followed by turkey’s post hoc test to separate means at 5% level of significance. 3. results 3.1. isolation of lactic acid bacteria a total of 350 lactic acid bacterial isolates were recovered from twenty different raw (10 raw) and fermented milk (10 yoghurt) of which 27 best performing isolates were selected for the probiotic functioning test. figure 1. colonies of lactic acid bacteria isolates on mrs (de man, rogosa and sharpe agar media agar) plates. 3.2. mass screening of lactic acid bacteria the mass screening of all isolated lactic acid bacteria was done using mrs broth and bromocresol purple as an indicator. the formation of a yellow colour indicated a positive result for fermentation or acidification whereas the absence of any colour change is considered as a negative result (figure 2). figure 2. mass selection of lactic acid bacterial isolates using micro titration plates (mrs broth + bcp indicator). mulatu et al. probiotic potential of lactic acid bacterial strains 203 3.3. in vitro analysis of probiotics properties of lab 3.3.1. gastric acid tolerance test among the 27 isolates 10 (37%) showed a significant tolerance to various ranges of gastric ph (2, 3 and 4, p < 0.05). most of the isolates were able to tolerate various gastric ph and the highest gastric acid tolerance were observed for isolate ad6 (od = 1.352 ± 0.063) at a gastric ph of 4 h at 24 h of incubation followed by nz26 (od = 0.870 ± 0.058) at the same gastric ph and incubation hour. the mean results are indicated here below at an absorbance of 630 nm (table 1). table 1. gastric acid tolerance test results of probiotic lactic acid bacteria. codes of isolates time of what (h) gastric ph 2 3 4 mean od at 630 nm ad6 0 0.510±0.005 0.422±0.001 0.517±0.001 2 0.495±0.006 0.596±0.115 0.523±0.006 4 0.509±0.001 0.502±0.002 0.528±0.028 24 0.667±0.108 0.510±0.003 1.352±0.063 nz26 0 0.511±0.007 0.492±0.010 0.514±0.003 2 0.489±0.001 0.498±0.003 0.510±0.009 4 0.505±0.002 0.502±0.001 0.533±0.020 24 0.726±0.094 0.501±0.002 0.870±0.058 bb26 0 0.507±0.003 0.725±0.034 0.511±0.006 2 0.506±0.003 0.588±0.044 0.511±0.005 4 0.512±0.004 0.502±0.005 0.510±0.001 24 0.511±0.006 0.741±0.057 0.519±0.007 dz9 0 0.519±0.007 0.503±0.008 0.546±0.027 2 0.515±0.017 0.521±0.019 0.521±0.019 4 0.504±0.010 0.502±0.001 0.524±0.012 24 0.522±0.012 0.512±0.005 0.804±0.112 g4 0 0.520±0.018 0.491±0.004 0.546±0.053 2 0.508±0.012 0.671±0.088 0.504±0.002 4 0.506±0.005 0.501±0.001 0.512±0.008 24 0.640±0.065 0.501±0.002 0.507±0.008 dz5 0 0.508±0.001 0.496±0.004 0.522±0.005 2 0.640±0.127 0.508±0.004 0.503±0.002 4 0.513±0.011 0.504±0.005 0.526±0.018 24 0.518±0.009 0.505±0.011 0.553±0.026 nz44 0 0.504±0.001 0.494±0.002 0.511±0.001 2 0.615±0.225 0.506±0.010 0.501±0.003 4 0.503±0.003 0.500±0.002 0.500±0.001 24 0.568±0.023 0.505±0.003 0.525±0.010 gb15 0 0.502±0.002 0.494±0.003 0.569±0.021 2 0.503±0.003 0.506±0.002 0.511±0.003 4 0.509±0.009 0.515±0.004 0.591±0.029 24 0.511±0.004 0.523±0.011 0.491±0.001 ad22 0 0.502±0.002 0.490±0.006 0.514±0.003 2 0.747±0.197 0.574±0.134 0.507±0.005 4 0.502±0.002 0.502±0.002 0.541±0.010 24 0.624±0.051 0.500±0.001 0.489±0.009 nz3 0 0.510±0.003 0.500±0.008 0.523±0.004 2 0.491±0.004 0.527±0.048 0.510±0.005 4 0.503±0.001 0.501±0.003 0.572±0.058 24 0.543±0.019 0.506±0.008 0.505±0.068 mulatu et al. east african journal of sciences volume 16(2): 199-212 204 table 1. continued. codes of isolates time of what (h) gastric ph 2 3 4 mean od at 630 nm ad6 0 0.510±0.005 0.422±0.001 0.517±0.001 2 0.495±0.006 0.596±0.115 0.523±0.006 4 0.509±0.001 0.502±0.002 0.528±0.028 24 0.667±0.108 0.510±0.003 1.352±0.063 nz26 0 0.511±0.007 0.492±0.010 0.514±0.003 2 0.489±0.001 0.498±0.003 0.510±0.009 4 0.505±0.002 0.502±0.001 0.533±0.020 24 0.726±0.094 0.501±0.002 0.870±0.058 bb26 0 0.507±0.003 0.725±0.034 0.511±0.006 2 0.506±0.003 0.588±0.044 0.511±0.005 4 0.512±0.004 0.502±0.005 0.510±0.001 24 0.511±0.006 0.741±0.057 0.519±0.007 dz9 0 0.519±0.007 0.503±0.008 0.546±0.027 2 0.515±0.017 0.521±0.019 0.521±0.019 4 0.504±0.010 0.502±0.001 0.524±0.012 24 0.522±0.012 0.512±0.005 0.804±0.112 g4 0 0.520±0.018 0.491±0.004 0.546±0.053 2 0.508±0.012 0.671±0.088 0.504±0.002 4 0.506±0.005 0.501±0.001 0.512±0.008 24 0.640±0.065 0.501±0.002 0.507±0.008 dz5 0 0.508±0.001 0.496±0.004 0.522±0.005 2 0.640±0.127 0.508±0.004 0.503±0.002 4 0.513±0.011 0.504±0.005 0.526±0.018 24 0.518±0.009 0.505±0.011 0.553±0.026 nz44 0 0.504±0.001 0.494±0.002 0.511±0.001 2 0.615±0.225 0.506±0.010 0.501±0.003 4 0.503±0.003 0.500±0.002 0.500±0.001 24 0.568±0.023 0.505±0.003 0.525±0.010 gb15 0 0.502±0.002 0.494±0.003 0.569±0.021 2 0.503±0.003 0.506±0.002 0.511±0.003 4 0.509±0.009 0.515±0.004 0.591±0.029 24 0.511±0.004 0.523±0.011 0.491±0.001 ad22 0 0.502±0.002 0.490±0.006 0.514±0.003 2 0.747±0.197 0.574±0.134 0.507±0.005 4 0.502±0.002 0.502±0.002 0.541±0.010 24 0.624±0.051 0.500±0.001 0.489±0.009 nz3 0 0.510±0.003 0.500±0.008 0.523±0.004 2 0.491±0.004 0.527±0.048 0.510±0.005 4 0.503±0.001 0.501±0.003 0.572±0.058 24 0.543±0.019 0.506±0.008 0.505±0.068 mulatu et al. probiotic potential of lactic acid bacterial strains 205 table 1. continued. codes of isolates time of what (h) gastric ph 2 3 4 mean od at 630 nm ad17 0 0.506±0.002 0.548±0.007 0.529±0.009 2 0.514±0.009 0.534±0.008 0.509±0.008 4 0.515±0.009 0.502±0.004 0.544±0.029 24 0.527±0.002 0.663±0.103 0.502±0.006 ad29 0 0.513±0.007 0.487±0.001 0.513±0.007 2 0.495±0.007 0.531±0.017 0.505±0.002 4 0.519±0.022 0.509±0.004 0.512±0.006 24 0.532±0.016 0.501±0.003 0.520±0.009 bb3 0 0.511±0.005 0.532±0.012 0.534±0.003 2 0.506±0.003 0.544±0.015 0.521±0.002 4 0.524±0.027 0.507±0.002 0.526±0.005 24 0.521±0.006 0.568±0.017 0.524±0.010 bb31 0 0.509±0.004 0.509±0.009 0.520±0.004 2 0.509±0.004 0.526±0.016 0.511±0.005 4 0.516±0.003 0.515±0.014 0.517±0.005 24 0.526±0.007 0.644±0.076 0.523±0.007 bb50 0 0.500±0.001 0.495±0.004 0.518±0.017 2 0.507±0.005 0.511±0.008 0.503±0.002 4 0.500±0.002 0.503±0.005 0.501±0.002 24 0.505±0.003 0.545±0.019 0.510±0.005 bb60 0 0.496±0.001 0.493±0.003 0.525±0.028 2 0.505±0.002 0.504±0.002 0.540±0.070 4 0.498±0.001 0.514±0.002 0.500±0.007 24 0.506±0.003 0.523±0.012 0.511±0.009 bb61 0 0.513±0.005 0.547±0.006 0.522±0.002 2 0.506±0.002 0.531±0.003 0.524±0.009 4 0.514±0.004 0.503±0.002 0.517±0.016 24 0.528±0.004 0.631±0.058 0.538±0.011 bb64 0 0.502±0.004 0.500±0.010 0.504±0.003 2 0.510±0.007 0.521±0.007 0.509±0.009 4 0.511±0.012 0.507±0.005 0.502±0.005 24 0.513±0.006 0.583±0.023 0.509±0.003 bb7 0 0.503±0.004 0.496±0.002 0.518±0.003 2 0.502±0.001 0.506±0.003 0.502±0.001 4 0.506±0.002 0.508±0.004 0.504±0.002 24 0.511±0.001 0.533±0.017 0.500±0.012 dz1 0 0.509±0.008 0.528±0.022 0.507±0.003 2 0.502±0.002 0.508±0.010 0.500±0.002 4 0.502±0.004 0.509±0.008 0.505±0.005 24 0.505±0.001 0.520±0.010 0.503±0.001 mulatu et al. east african journal of sciences volume 16(2): 199-212 206 table 1. continued. figure 3. gastric acid ph interaction effects of probiotic lactic acid bacterial strains with incubation time. the highest tolerance of gastric acid was observed for isolate ad6 at ph 4, 24 h of incubation followed by nz26 at an absorbance of 630 nm. the ph and time interaction effects of the selected strains varied among the probiotic bacterial isolates. codes of isolates time of what (h) gastric ph 2 3 4 mean od at 630 nm dz13 0 0.511±0.001 0.494±0.018 0.520±0.003 2 0.508±0.032 0.504±0.002 0.506±0.003 4 0.506±0.002 0.505±0.002 0.561±0.013 24 0.575±0.057 0.502±0.001 0.766±0.097 g19 0 0.508±0.002 0.487±0.004 0.520±0.002 2 0.492±0.001 0.506±0.002 0.504±0.001 4 0.510±0.006 0.509±0.003 0.519±0.006 24 0.570±0.017 0.501±0.004 0.515±0.006 g23 0 0.501±0.003 0.498±0.003 0.517±0.003 2 0.504±0.002 0.504±0.003 0.509±0.009 4 0.503±0.002 0.502±0.001 0.505±0.004 24 0.509±0.003 0.578±0.059 0.508±0.004 g25 0 0.501±0.001 0.496±0.003 0.508±0.006 2 0.503±0.002 0.510±0.005 0.502±0.002 4 0.511±0.011 0.508±0.006 0.504±0.003 24 0.510±0.002 0.536±0.012 0.499±0.008 g27 0 0.502±0.002 0.512±0.003 0.519±0.003 2 0.508±0.006 0.515±0.013 0.510±0.006 4 0.503±0.004 0.514±0.008 0.512±0.003 24 0.509±0.006 0.578±0.018 0.526±0.009 g37 0 0.504±0.001 0.502±0.006 0.511±0.001 2 0.496±0.005 0.570±0.063 0.501±0.002 4 0.500±0.002 0.507±0.002 0.514±0.008 24 0.542±0.008 0.503±0.002 0.528±0.003 nz39 0 0.510±0.004 0.502±0.009 0.520±0.002 2 0.494±0.001 0.510±0.007 0.510±0.010 4 0.512±0.004 0.503±0.002 0.528±0.004 24 0.583±0.014 0.515±0.005 0.670±0.056 mulatu et al. probiotic potential of lactic acid bacterial strains 207 3.3.2. bile salt tolerances test the bile salt tolerance efficiency of twenty-seven (27) selected probiotic lactic acid bacterial strains are indicated in table 2. of the twenty-seven (27) probiotic strains isolated, g25 (od = 0.733 ± 0.103) isolate was able to tolerate 2% of bile salt at 2 h of incubation time. four isolates, namely, dz3 (od = 0.578 ± 0.103), g37 (od = 0.657 ± 0.046), ad22 (od = 0.683 ± 0.072) and nz3 (od = 0.694 ± 0.070) showed a significant tolerance of 1% of bile salt concentration at 24 h of incubation whereas strains gb 15 (od = 0.668 ± 0.044), bb7 (od = 0.595 ± 0.093) and bb50 (od = 0.681 ± 0.073) tolerate (2%, 24h of incubation at an absorbance of 630 nm). in the present study, most of the probiotic strains were tolerant and survived different bile salt concentrations. table 2. bile salt tolerance efficiency of probiotic lactic acid bacterial isolates. codes of isolates time bile salt concentration 0.3% 1% 1.5% 2% mean od at 630 nm g25 0 0.500±0.001 0.529±0.008 0.502±0.005 0.505±0.003 2 0.503±0.006 0.503±0.004 0.495±0.004 0.733±0.103 4 0.505±0.003 0.491±0.001 0.495±0.015 0.533±0.005 24 0.513±0.001 0.495±0.002 0.519±0.033 0.519±0.008 bb50 0 0.507±0.004 0.509±0.003 0.507±0.004 0.509±0.003 2 0.498±0.004 0.503±0.002 0.502±0.008 0.531±0.012 4 0.501±0.004 0.493±0.000 0.507±0.005 0.527±0.001 24 0.530±0.007 0.500±0.006 0.497±0.011 0.681±0.073 nz3 0 0.515±0.002 0.506±0.007 0.505±0.002 0.506±0.004 2 0.528±0.049 0.503±0.005 0.497±0.001 0.501±0.004 4 0.511±0.005 0.549±0.011 0.500±0.007 0.502±0.001 24 0.487±0.004 0.694±0.070 0.033±0.004 0.496±0.003 ad22 0 0.518±0.014 0.515±0.013 0.503±0.005 0.507±0.004 2 0.513±0.011 0.520±0.000 0.503±0.012 0.501±0.005 4 0.512±0.005 0.522±0.011 0.510±0.018 0.509±0.006 24 0.487±0.004 0.683±0.072 0.022±0.004 0.495±0.001 gb15 0 0.503±0.002 0.510±0.006 0.510±0.008 0.499±0.009 2 0.508±0.013 0.503±0.003 0.495±0.004 0.576±0.086 4 0.511±0.004 0.495±0.004 0.506±0.015 0.554±0.024 24 0.529±0.019 0.506±0.011 0.507±0.004 0.668±0.044 g37 0 0.547±0.002 0.522±0.006 0.517±0.007 0.524±0.005 2 0.537±0.027 0.511±0.005 0.505±0.006 0.517±0.011 4 0.539±0.009 0.528±0.010 0.528±0.001 0.520±0.014 24 0.502±0.006 0.657±0.046 0.021±0.009 0.498±0.002 bb7 0 0.491±0.004 0.517±0.001 0.516±0.002 0.512±0.002 2 0.502±0.010 0.515±0.006 0.498±0.004 0.564±0.020 4 0.512±0.005 0.496±0.003 0.506±0.003 0.564±0.021 24 0.519±0.007 0.506±0.002 0.511±0.009 0.595±0.093 g19 0 0.533±0.013 0.531±0.013 0.536±0.006 0.514±0.014 2 0.536±0.003 0.515±0.004 0.542±0.016 0.526±0.008 4 0.518±0.005 0.510±0.003 0.583±0.016 0.507±0.001 24 0.497±0.009 0.509±0.005 0.013±0.007 0.509±0.005 bb61 0 0.501±0.001 0.506±0.001 0.534±0.086 0.508±0.002 2 0.506±0.006 0.504±0.001 0.494±0.002 0.520±0.005 4 0.512±0.007 0.493±0.004 0.503±0.008 0.507±0.001 24 0.518±0.002 0.507±0.007 0.514±0.009 0.507±0.005 dz13 0 0.507±0.002 0.510±0.012 0.512±0.011 0.504±0.004 2 0.501±0.004 0.507±0.017 0.510±0.006 0.502±0.001 4 0.508±0.007 0.506±0.004 0.504±0.003 0.488±0.005 24 0.578±0.103 0.031±0.003 0.516±0.018 0.510±0.012 mulatu et al. east african journal of sciences volume 16(2): 199-212 208 table 2. continued. codes of isolates time bile salt concentration 0.3% 1% 1.5% 0.3% mean od at 630 nm ad17 0 0.506±0.004 0.512±0.005 0.511±0.003 0.505±0.003 2 0.539±0.015 0.506±0.002 0.506±0.014 0.558±0.039 4 0.510±0.001 0.505±0.009 0.498±0.001 0.509±0.001 24 0.517±0.005 0.506±0.017 0.496±0.001 0.500±0.002 ad29 0 0.524±0.017 0.523±0.013 0.502±0.004 0.514±0.007 2 0.537±0.038 0.506±0.001 0.499±0.005 0.510±0.001 4 0.509±0.003 0.502±0.001 0.515±0.008 0.505±0.003 24 0.525±0.035 0.504±0.003 0.018±0.011 0.508±0.007 ad6 0 0.516±0.007 0.500±0.004 0.500±0.002 0.492±0.004 2 0.507±0.004 0.503±0.006 0.489±0.001 0.497±0.001 4 0.513±0.002 0.504±0.002 0.510±0.013 0.503±0.000 24 0.479±0.007 0.538±0.017 0.028±0.001 0.508±0.011 bb26 0 0.511±0.060 0.508±0.002 0.535±0.027 0.503±0.001 2 0.513±0.014 0.515±0.007 0.501±0.016 0.518±0.008 4 0.514±0.009 0.495±0.001 0.497±0.004 0.508±0.002 24 0.519±0.002 0.499±0.001 0.503±0.003 0.516±0.007 bb3 0 0.499±0.002 0.507±0.004 0.502±0.001 0.503±0.001 2 0.501±0.004 0.501±0.001 0.499±0.006 0.538±0.012 4 0.507±0.001 0.489±0.004 0.515±0.012 0.528±0.011 24 0.523±0.002 0.498±0.001 0.500±0.002 0.563±0.045 bb31 0 0.505±0.003 0.506±0.001 0.501±0.010 0.506±0.003 2 0.517±0.003 0.542±0.047 0.492±0.002 0.525±0.021 4 0.507±0.004 0.497±0.003 0.520±0.021 0.505±0.002 24 0.523±0.006 0.516±0.012 0.522±0.021 0.502±0.002 bb60 0 0.496±0.001 0.512±0.004 0.515±0.007 0.506±0.004 2 0.510±0.006 0.509±0.005 0.536±0.067 0.545±0.024 4 0.508±0.003 0.494±0.003 0.509±0.013 0.520±0.002 24 0.517±0.010 0.505±0.018 0.500±0.003 0.515±0.004 bb64 0 0.510±0.002 0.522±0.015 0.512±±0.004 0.509±0.005 2 0.523±0.003 0.508±0.002 0.535±0.045 0.544±0.024 4 0.504±0.001 0.498±0.004 0.498±0.004 0.508±0.004 24 0.521±0.002 0.499±0.001 0.497±0.001 0.515±0.012 dz1 0 0.499±0.002 0.514±0.010 0.504±0.004 0.506±0.002 2 0.522±0.003 0.506±0.002 0.508±0.014 0.520±0.007 4 0.509±0.002 0.507±0.021 0.502±0.004 0.547±0.011 24 0.519±0.003 0.499±0.005 0.508±0.006 0.575±0.039 dz5 0 0.522±0.009 0.529±0.016 0.509±0.004 0.523±0.008 2 0.5080±.003 0.502±0.005 0.516±0.001 0.514±0.003 4 0.516±0.003 0.502±0.001 0.527±0.007 0.510±0.002 24 0.488±0.010 0.502±0.003 0.007±0.002 0.495±0.005 mulatu et al. probiotic potential of lactic acid bacterial strains 209 table 2. continued. figure 4. bile salt concentration tolerance interaction of lactic acid bacterial strains with incubation time. the highest survival efficiency of bile salt was recorded at a bile salt concentration of 2%, 2h of incubation. most of the isolates able to grow and survive various bile salt concentrations. codes of isolates time bile salt concentration 0.3% 1% 1.5% 0.3% mean od at 630 nm dz9 0 0.572±0.021 0.551±0.008 0.565±0.025 0.510±0.005 2 0.528±0.013 0.521±0.002 0.535±0.016 0.517±0.003 4 0.554±0.025 0.521±0.005 0.539±0.018 0.511±0.001 24 0.501±0.009 0.507±0.007 0.0310±0.033 0.507±0.007 g23 0 0.504±0.004 0.530±0.006 0.506±0.002 0.506±0.002 2 0.505±0.006 0.504±0.003 0.489±0.001 0.507±0.000 4 0.502±0.003 0.495±0.005 0.497±0.004 0.512±0.003 24 0.514±0.006 0.500±0.006 0.502±0.006 0.548±0.017 g27 0 0.500±0.002 0.500±0.002 0.506±0.004 0.522±0.016 2 0.504±0.001 0.499±0.014 0.506±0.005 0.526±0.016 4 0.516±0.025 0.515±0.012 0.490±0.004 0.531±0.036 24 0.500±0.003 0.527±0.009 0.511±0.015 0.497±0.001 g4 0 0.544±0.003 0.536±0.014 0.516±0.003 0.517±0.011 2 0.544±0.015 0.535±0.014 0.510±0.002 0.513±0.001 4 0.533±0.006 0.507±0.010 0.525±0.006 0.508±0.001 24 0.513±0.014 0.509±0.029 0.022±0.005 0.505±0.008 nz26 0 0.508±0.006 0.495±0.009 0.512±0.009 0.519±0.022 2 0.517±0.019 0.511±0.006 0.498±0.001 0.519±0.010 4 0.512±0.010 0.500±0.003 0.503±0.004 0.505±0.002 24 0.486±0.012 0.501±0.005 0.034±0.002 0.499±0.004 nz39 0 0.511±0.002 0.497±0.004 0.497±0.000 0.508±0.005 2 0.502±0.005 0.501±0.005 0.500±0.002 0.512±0.011 4 0.506±0.004 0.531±0.004 0.504±0.004 0.503±0.001 24 0.505±0.025 0.564±0.046 0.033±0.003 0.497±0.003 nz44 0 0.509±0.003 0.503±0.007 0.498±0.002 0.527±0.031 2 0.510±0.005 0.516±0.014 0.495±0.002 0.499±0.002 4 0.504±0.006 0.506±0.013 0.503±0.009 0.506±0.003 24 0.488±0.003 0.501±0.008 0.013±0.014 0.496±0.005 mulatu et al. east african journal of sciences volume 16(2): 199-212 210 4. discussion twenty-seven isolates showed significant acidification activity, which is 4.2 higher than the other isolates. this is in agreement with the results of fguiri et al. (2016) that lactobacillus plantarum was selected as fast acid producer lactobacillus isolate from milk. a rapid decrease in ph is essential for coagulation and prevention or reduction of growth of adventitious micro flora in yoghurt production. the fast-acidifying strains are therefore good candidates for dairy fermentation process as primary starter culture while the poor acidification strains can be used as an adjunct culture depending on other properties (ayad et al., 2004). among the 27 isolates, 10 (37%) showed a significance tolerance to various ranges of gastric ph. the tolerance efficiency was varied among the isolated strains. isolates, namely, ad6 (1.352 ± 0.063), nz26 (od = 0.870 ± 0.058) and dz9 (od = 0.804 ± 0.112) have shown the highest tolerance of gastric ph (4, 24 h of incubation) compared to the rest probiotic lactic acid bacterial strains at an absorbance of 630 nm. the least gastric tolerance was observed for the isolate ad6 (od = 0.422 ± 0.001) at a gastric ph of 3 at 0 h of incubation hour. bacteria that would resist ph values ranging from 2.0 to 8.0 in the gastrointestinal tract if consumed (hood and zottola, 1988). hence, probiotic cultures must survive in the environment with gastric and bile acids, when viable cells go through the gastrointestinal tract. resisting the ph of 3.0 for 24 h and growing in the medium containing 1,000 ppm of bile acids are considered as standards for acid and bile tolerance of probiotic culture (itoh, 1992). a study conducted by gilliland et al. (1984) reported that when a 0.3 absorbance is achieved after at least 2 h of incubation at 37oc in the presence of gastric ph between 1.5 and 4.0, a microorganism can be considered tolerant or resistant to gastric ph. in line with this result, ten out of the 27 isolates tested can be considered tolerant to gastric ph. the highest absorbance was recorded for isolate ad6 (od = 1.352 ± 0.063) at a ph of 4, 24h of incubation at 37 oc. however, survival of bacterial strains in human gastric juice is a more accurate indication of the ability of strains to survive passage through the stomach (draser et al.,1969). similarly, arokiyamary and sivakumaar (2011) indicated that lactic acid bacteria isolated from different dairy products were used as a potential probiotic and able to survive in acidic environment (ph = 4 to 6.5). on the other hand, a study conducted by lee and salminen (1995) revealed that the lab survival in low ph is very important for bearing initial stress in the stomach at the application level because, when lactic acid bacteria enters the human body, the first constraint is gastric acid with very low ph level around 2-3. the result of this study showed that probiotic lactic acid bacterial isolates are able to tolerate gastric ph of 2, 3 and 4. the ph and time interaction effects of the selected strains varied among the probiotic bacterial isolates. the highest tolerance of gastric acid was observed for isolate ad6 at ph 4, 24 h of incubation followed by nz26 at an absorbance of 630 nm (figure 3). the effect of acidity on the viability of the isolates was assessed by adjusting the growth medium to different ph values (2, 3 and 4). the present results suggest that probiotic lactic acid bacterial isolates could successfully transit the human stomach and may be capable of reaching the intestinal environment and functioning effectively therein. bile salt tolerance is one of the selection criteria whether certain microbes have potentially probiotic function or not presenting the potential of using lactic acid bacteria as effective probiotics it is generally considered necessary to evaluate their ability to resist the effects of bile acids (goldin et al., 1992). of the twenty-seven probiotic strains isolated, g25 (od = 0.733 ± 0.103) isolate was able to tolerate 2% (w/v) of bile salt at 2h of incubation time. four isolates dz3 (od = 0.578 ± 0.103), g37 (od = 0.657 ± 0.046), ad22 (od = 0.683 ± 0.072) and nz3 (od = 0.694 ± 0.070) showed a significance tolerance of 1% (w/v) of bile salt concentration at 24h of incubation whereas strains gb 15 (od = 0.668 ± 0.044), bb7 (od = 0.595 ± 0.093) and bb50 (od = 0.681 ± 0.073) tolerate 2% (w/v), 24h of incubation at an absorbance of 630 nm). in similar study, houque et al. (2010) studied lactobacillus sp. isolated four isolates from yogurts and found that all the isolates were able to tolerate bile acid at the rate of 2%. in a similar study, behboud et al. (2011) reported in indicated that resistance to bile salts is considered an important parameter for selecting probiotic strains. a concentration of 0.15–0.3% (w/v) of bile salt has been recommended as a suitable concentration for selecting probiotic bacteria for human use. in a similar study conducted by torshizi et al. (2008), the survival at bile salt condition is one of the main criteria for in vitro selection of potentially probiotic bacteria and critical points for the microbes. because some of lactic acid bacteria are able to survive at bile salt condition. hydrolyses of bile salt decreases the toxic effect of the bile salt to the lactic acid bacteria. in the current study, most lactic acid bacteria isolates are able to survive bile salt. the highest survival efficiency of bile salt was recorded at a bile salt concentration of 2% (w/v), 2h of incubation. most of the isolates were able to grow and survive various bile salt mulatu et al. probiotic potential of lactic acid bacterial strains 211 concentrations (figure 4). the high activity of bile salt hydrolysed in lumen of intestine could reduce bile salt conjugation ability to break down lipid (de smet et al., 1995). bile salt hydrolytic activity may contribute to the resistance of lactic acid bacteria to the toxicity of conjugated bile salts in the duodenum and therefore is an important colonization factor (shaikh and shah, 2013). this may explain the variation recorded among the tested strains in this study. finally, the present study showed that traditional dairy products are excellent sources of probiotic lactic acid bacteria with the ability to tolerate various gastric and bile salt stress. the isolated strains exhibited an excellent quality of gastric and bile salt tolerance efficiency. in the present study, most of the probiotic strains tolerated and survived different bile salt concentrations. 5. conclusion the results obtained in the present study have demonstrated that raw milk and yoghurt contained several groups of probiotic lactic acid bacteria. the findings revealed that naturally occurring lactic acid bacteria isolated from dairy products have the potential for probiotic applications in the dairy industry in the country. the results also suggest that the lactic acid bacterial strains can be selected as good 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mojgani., n., esmaeilkhanian, s. and grimes, j.l. 2008. screening of indigenous strains of lactic acid bacteria for development of a probiotic for poultry. australasian journal of animal sciences, 21: 1495–1500. yeshambel taye, tadesse degu, haben fesseha and mesfin mahewos. 2021. isolation and identification of lactic acid bacteria from cow milk and milk products. the scientific world journal, 4697445. https://doi.org/10.1155/2021/4697445. yusuf, n., syed, a.h., aidil, a.h. and yuanda, s. 2018. probiotics and their potential preventive and therapeutic role for cancer, high serum cholesterol, and allergic and hiv diseases. biomed research international, 1–17. https://doi.org/10.1155/2021/4697445 ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(2): 155-170 licensed under a creative commons *corresponding author: abune.the@gmail.com attribution-noncommercial 4.0 international license. genetic gain in yield potential and related traits of finger millet [eleusine coracana (l.) gaertn] in ethiopia abunu marefia1*, alemu abate2 and muluken bantayehu2 1adet agricultural research center, p.o. box 8, bahir dar, ethiopia 2 department of plant science, bahir dar university, p.o. box 79, bahir dar, ethiopia abstract background: genetic gains made on crop improvement are important for breeders to develop new crop varieties. however, information on the hitherto genetic gains made in the improvement of finger millet is scant and no assessment of this trait has been done on improved finger millet varieties in ethiopia. objective: a field experiment was conducted to estimate the genetic gain in yield and related traits of finger millet varieties released in ethiopia between 1999 and 2019. materials and methods: twenty finger millet varieties were evaluated in 2019/20 main cropping season at adet and finoteselam research sites using a randomized complete block design with three replications. data were collected both on plot and plant basis, and then subjected to variance, correlation and stepwise regression analysis. results: the results revealed significant differences among the varieties and locations for almost all traits. the overall increases in grain yield over the oldest varieties were 449.03 kg ha–1 (22.49%) and 390.95 kg ha–1 (19.22%) at adet and finoteselam, respectively. the estimated annual and relative genetic gain was 30.88 kg ha–1 year–1 and 1.55% year–1 at adet and 24.39 kg ha–1 year–1 and 1.2% year–1 at finoteselam. biomass yield and harvest index together contributed 99.74% and 99.42% of the variation in grain yield at adet and finoteselam, respectively. in addition, number of tillers plant–1 and ears plant–1 contributed to the change in grain yield as they were highly correlated with year of variety release. conclusion: it is concluded that, a substantial gain has been made in grain yield and related traits of hitherto developed finger millet varieties in the country, which is largely attributed to varietal change during the period 1999 to 2019. however, the gain obtained was low as compared to the gain made on other crops and the crop’s potential, suggesting further breeding efforts need to be made in the future as this crop’s genetic potential has not yet been fully exploited. keywords: eleusine coracana; finger millet; genetic gain 1. introduction finger millet [eleusine coracana (l.) gaertn] is a tetraploid (2n = 4x = 36, aabb) self-pollinating crop belonging to the family poaceae, sub family chloridoideae, genus eleusine. the genus eleusine contains about 10 species, in which some are tetraploids and others are diploids (hilu et al., 1979). eleusine coracana is believed to be a modern finger millet evolved from its wild progenitor, eleusine coracana subsp. africana (goron and raizada, 2015). archaeological records revealed that, the primary center of origin for finger millet is east africa (particularly the ethiopia highlands and uganda), domesticated around 5000 years ago (hilu et al., 1979). subsequently, it is introduced to the western ghats of india (upadhyaya et al., 2007). nowadays, it is extensively cultivated in east and central africa (obilana, 2003), and south asia especially in india (upadhyaya et al., 2007). ethiopia is the center of origin and diversity for finger millet (hilu et al., 1979); however, its genetic potential is not as such exploited (zigale semahegn et al, 2021). accordingly, the average productivity of finger millet in ethiopia is low (2504 kg ha–1) (csa, 2021) as compared to its potential (4000 kg ha–1) (kebede dessalegn et al., 2019). this is due to numerous obstacles, including unavailability of improved varieties and poor research attention towards mailto:abune.the@gmail.com abunu et al. east african journal of sciences volume 16(2): 155-170 156 the crop (erenso degu et al., 2009). this indicates further research effort has to be made in the country and in the world as large. because, a successful breeding program is likely to increase genetic gain, including grain yield (heisey et al., 2002). in ethiopia, research on finger millet was initiated at debre zeit agricultural research center in the late 1950s. much of the early efforts have focused on collection, conservation and characterization of finger millet germplasms. then, the national sorghum improvement program based at melkassa re-initiated finger millet research in 1986 (erenso degu et al., 2009). now, research emphasis has been given via national sorghum and millet research program, regional research institutes and higher learning institutions (zigale semahegn et al, 2021). since then, efforts have been underway to develop high yielding finger millet varieties (erenso degu et al., 2009). thus, about 26 improved finger millet varieties have been registered and released from different research centers (moa, 2020). despite the availability of these varieties, the genetic gain made on finger millet varieties over the year of variety release has not been studied yet. estimation and documentation of genetic gain is useful as it helps breeders to make decisions about what breeding strategy they should follow, whether they ought to pursue or if changes are required. it also enables to identify traits of potential value for future breeding enhancement and target them for higher productivity and production. evaluation of popular cultivars from different years in common environments is thus the most comprehensive and direct method that has been used to estimate progress in yield improvement (abeledo et al., 2003). in ethiopia, genetic gain made has been studied in barley (wondimu fekadu et al., 2013), teff (fano dargo et al., 2016), maize (michael kebede, 2016), durum wheat (mekuria temtme, 2017) and bread wheat (endashaw girma et al., 2019) by comparing old and modern varieties. they all found and documented the level of genetic improvement for grain yield and associated traits. however, there is no study documenting genetic gain on finger millet in the area, elsewhere in ethiopia and in other countries. therefore, the objective of this study was to estimate the genetic gain in grain yield and related traits of finger millet varieties of ethiopia released between 1999 and 2019. 2. materials and methods 2.1. description of the study areas the experiment was conducted during 2019/20 main cropping season at adet and finoteselam agricultural research sites. adet is located at longitude of 37o 28' e and latitude of 11o 17' n with an altitude of 2240 meters above sea level. during the study period, the site received an average annual rainfall and temperature of 1335 mm and 17.68 oc, respectively. whereas, finoteselam is located at longitude of 37o 15' e and latitude of 10o 41' n in northern highlands of ethiopia with an altitude of 1820 meters above sea level. the average annual rainfall and temperature were 1263 mm and 22.82 oc, respectively during the study period [national meteorological agency, bahir dar branch (2019)]. 2.2. experimental materials and field management twenty finger millet varieties acquired from various agricultural research centers in ethiopia were used for the study. the experiments were laid out in a randomized complete block design with three replications. each plot consisted of four rows with row spacing of 0.4 m; and the size of the plot was 5 m x 1.6 m. npsb blended and urea fertilizers were applied at the rate of 100 kg ha–1 and 50 kg ha–1 in that order. the total amount of nps fertilizer was applied during planting, whereas the total amount of urea was applied at tillering stage. other agronomic practices were carried out following the standard procedure. 2.3. data collection and analysis 2.3.1. data collection data were collected both on plot and plant basis. among the plot basis, days to heading, days to maturity, grain filling period, head blast severity (%), biomass yield (kg), grain yield (kg), harvest index (%), biomass production rate (kg) and seed growth rate (kg) were recorded. however, effective tillers per plant, ears per plant, fingers per ear, plant height (cm) and finger length (cm) were recorded on plant basis. 2.3.2. data analysis data were subjected to analysis of variance using the sas software. treatments and replications were class variables, while response variables were the measured traits. differences between treatment means were determined using duncan multiple range test, and employed depending on significance of analysis of variance. tests were made by f-test to confirm the homogeneity of error mean square between the two sites. data transformation was done for number of tillers per plant, number of ears per plant, and head blast severity as they exhibited heterogeneity of variance. the collected data were computed as follows; yij = μ + gi +rj + eij abunu et al. genetic gain in yield and related traits of finger millet 157 where, yij = observed value of genotype i in block j; μ = grand mean of the experiment; gi = effect of variety i; rj = effect of block; j and eij = random error effect of variety i in block j. genotypic correlations were estimated using the standard procedure suggested by kashiani and saleh (2010) from the corresponding variance and covariance components. thus, correlation was calculated as, genotypic correlation coefficient (rgxy) = covgxy √σ2gx.σ2gy where, rg (xy) = genotypic correlation coefficient between trait x and y; covg (xy) = genotypic covariance between trait x and y and vg (x) and vg (y) = genotypic variance for trait x and y. the mean performance of released varieties was regressed on year of release starting from 1999 using the first released variety as a base to calculate the genetic gain for each trait considered in the present study. a linear model (y = bx + a) was used between response variables as a dependent variable, y; year of release as an independent variable, x; intercept, a; and regression coefficient (the slope of the line), b (gomez and gomez, 1984). the breeding effect was estimated as genetic gain for grain yield and yield related traits in finger millet improvement by regressing mean of each variable for each variety against the year of release of that variety (0 to 20 years) using proc reg procedure. the year of variety release was determined as the number of years since 1999. moreover, the relative genetic gain achieved over the last 20 years for finger millet varieties were determined as a ratio of annual genetic gain to the corresponding mean value of oldest variety and expressed as percentage. likewise, total relative genetic gain was computed as ratio of overall mean minus mean of oldest varieties to the corresponding mean value of oldest variety and expressed as percentage (rutkoski, 2019). stepwise regression analysis was carried out on the varietal mean to determine those variables contributing much to yield variation using proc reg procedure. 3. results and discussion 3.1. analysis of variance homogeneity of error mean squares between the two sites was determined using f-test. the two locations did not show homogeneity of error variance. consequently, the analysis was done separately for each location. analysis of variance for the tested varieties at adet revealed very highly significant (p ≤ 0.001) differences for all traits except number of tillers per plant and number of ears per plant (table 1). likewise, the analysis of variance at finoteselam revealed very highly significant (p ≤ 0.001) differences for all traits except grain yield which showed highly significant (p ≤ 0.01) differences (table 1). as a result, the performance of the tested varieties were variable, indicating the existence of enormous amounts of genetic variability for growth and yield attributes among them; and among locations. such phenotypic expressions and yield potential are based on its genetics, the environment and the genotype by environment interactions. they provide breeders with the opportunity to select or develop high yielding varieties, or to combine or transfer genes with desirable traits. genetic variations in finger millet have been also revealed in previous studies (kebere bezaweletaw et al., 2006; ganapathy et al., 2011; hailegebrial kinfe et al., 2017; ashok et al., 2018; manoj et al., 2019; yaregal damtie et al., 2019). the authors all reported that, the variations among traits of finger millet genotypes are important for every breeding program as they can either affect yield positively or negatively, depending on the type of variation. high genetic variability brings the much needed information for genetic improvement program of finger millet (manoj et al., 2019). moreover, similar results were reported for teff (fano dargo et al., 2016), maize (michael kebede, 2016), durum wheat (mekuria temtme, 2017) and bread wheat (endashaw girma et al., 2019). thus, measurement and evaluation of genetic variability are an essential step in drawing meaningful conclusions from a given set of phenotypic observations (reddy and reddy, 2011). abunu et al. east african journal of sciences volume 16(2): 155-170 158 table 1. mean and mean square of the traits of the varieties tested at adet and finoteselam. trait adet finoteselam mean treatment (df=19) error (df=38) cv (%) r2 (%) mean treatment (df=19) error (df=38) cv (%) r2 (%) dh 102.13 157.21*** 0.41 0.63 99.48 99.13 159.63*** 0.89 0.95 98.89 dm 162.78 186.64*** 1.83 0.83 98.11 155.92 144.35*** 1.43 0.77 98.06 gfp 60.65 51.24*** 1.76 2.19 93.67 56.78 74.57*** 1.92 2.44 95.10 ph 71.04 152.57*** 21.91 6.59 78.50 80.90 204.80*** 43.14 8.12 70.61 fl 7.02 15.00*** 0.46 9.70 94.24 7.79 12.17*** 0.29 6.89 95.47 tpp 4.09 0.17ns 0.11 16.73 47.30 3.34 0.14*** 0.04 10.60 65.81 epp 5.04 0.13ns 0.09 13.53 45.40 4.34 0.11*** 0.03 8.07 65.79 fpe 5.72 6.18*** 0.44 11.58 87.80 5.84 2.65*** 0.17 7.04 88.76 by 10807.00 5185018.79*** 1320080.10 10.63 68.13 9955.00 4194905.10** 1347645.50 11.66 61.14 gy 2397.00 258895.36*** 32501.81 7.52 80.66 2386.00 224196.23*** 34258.20 7.76 76.74 hi 22.28 5.95*** 1.36 5.23 69.29 24.13 10.02*** 2.20 6.14 69.90 bpr 66.59 244.66*** 48.78 10.49 73.04 64.05 222.52*** 56.55 11.74 66.49 sgr 39.67 81.65*** 9.69 7.84 81.78 42.29 95.78*** 12.59 8.39 79.31 hb 15.65 6.37*** 0.38 16.88 89.34 26.71 5.46*** 0.19 8.78 93.49 note: *** = very highly significant at p ≤ 0.001; ** = highly significant at p ≤ 0.01; and ns = non-significant. df = degrees of freedom; r2 = coefficient of determination (%); cv = coefficient of variation (%); dh = days to 50% heading; dm = days to 50% maturity; gfp = grain filling period; ph = plant height (cm); fl = finger length (cm); tpp = tillers plant–1; epp = ears plant–1; fpe = fingers ear–1; by = biomass yield (kg ha–1 ); gy = grain yield (kg ha–1 ); hi = harvest index (%); bpr = biomass production rate (kg ha–1 day–1 ); sgr = seed growth rate (kg ha–1 day–1 ); and hb = head blast severity (%). abunu et al. genetic gain in yield and related traits of finger millet 159 3.2. progress made on yield and related traits of finger millet 3.2.1. progress made on grain yield at adet, strong positive relationship (y = 30.88x) was observed between mean grain yield and year of variety release (table 4 and figure 1). this implies that, the past finger millet breeding efforts in ethiopia resulted in an average grain yield increment from 1996.4 kg ha– 1 in 1999 to 2563.3 kg ha–1 in 2019 (table 2). the overall increase in grain yield over the oldest varieties was estimated to be 449.03 kg ha–1 (22.49 %). the estimated average annual rate of increase in grain yield was 30.88 kg ha–1 year–1 with an annual relative genetic gain of 1.55% year–1 (table 4). the maximum grain yield increment was recorded for the variety released in 2017 with a grain yield of 697.80 kg ha–1 (34.95%) followed by the varieties released in 2015 with a grain yield of 666.20 kg ha–1 (33.37%). however, the minimum grain yield increment was recorded for the variety released in 2009 with a grain yield of 114.70 kg ha–1 (5.75%) (table 2). generally, the percentage of increment in grain yield was estimated as 11.64% in 2002 and 28.40% in 2019 from the oldest varieties; tadese and padet released in 1999 (table 2). at finoteselam, the regression analysis also depicted a significant correlation (y = 24.39x) of grain yield with the year of variety release (table 5 and figure 1). the average grain yield on the varieties released in the year 1999 was 2033.80 kg ha–1 and reached 2624.60 kg ha–1 in 2019, indicating the overall increase was 390.95 kg ha–1 (19.22%) (table 3). likewise, the estimated average annual rate of increase in grain yield was 24.39 kg ha–1 year–1 with an annual relative genetic change of 1.2% year–1 (table 5). thus, the average grain yield on the varieties released in the year 1999 was 2033.80 kg ha–1 and reached 2624.60 kg ha–1 in 2019 (table 3). this result indicates that, finger millet breeders in ethiopia have made significant efforts to improve grain yield of the crop for the last 20 years. generally, the grain yield increment across the year of release in both locations was more or less linear (showed progressive increment) but not consistent (figure 1). this inconsistent trend could be due to the comparison among the varieties recommended for cultivation across different agro-ecologies and interactions of the varieties with the environments. such trend indicates that, genotypic change is an important source for increased grain yield. similarly, fano dargo et al. (2016) depicted that, the grain yield potential of teff was increased and estimated as 21.53 kg ha–1 year–1. in contrast to this result, michael kebede (2016) obtained a reduction in the grain yield potential of lowland maize varieties with an annual genetic change of –2.64 kg ha–1 year–1 and relative genetic gain of –0.16% kg ha–1 year–1. figure 1. relationship between grain yield and year of variety release at adet (a) and finoteselam (b). the progress made on finger millet was higher than the progress made on barley, 0.88% ha–1 year–1 (wondimu fekadu et al., 2013). however, there was no indication of yield plateau for the varieties tested on this study (figure 1), implying the possibility of further increase in yield of finger millet. the huge finger millet potential we have in ethiopia is not yet exploited due to lack of strong breeding programs that enable collection, characterization, evaluation and identification of desirable traits for genetic improvement (zigale semahegn et al., 2021). thus, the availability of wide genetic resources is a prerequisite to finger millet improvement. in spite of its wide resources, characterization of genetic resources is valuable for efficient and effective utilization in crop improvement programs. therefore, there is a potential and possibility of developing improved varieties targeting high yield, disease resistance, and other quality traits. thus, these results serve as a clue for breeders to further increase the yield of finger millet. abunu et al. east african journal of sciences volume 16(2): 155-170 160 table 2. temporal trends in mean grain and biomass yield of finger millet at adet. variety year of release gy increment by increment mean (kg ha–1) (%) mean (kg ha–1) (%) tadese 1999 padet 1999 1996.40 – – 9383.30 – – boneya 2002 2228.70 232.30 11.64 10048.30 665.00 7.09 degu 2005 2577.20 580.80 29.09 11541.70 2158.40 23.00 wama 2007 baruda 2007 2187.60 191.20 9.58 10416.65 1033.35 11.01 bareda 2009 gutie 2009 2111.10 114.70 5.75 9791.70 408.40 4.35 debatie 2010 2372.70 376.30 18.85 9425.00 41.70 0.44 necho 2011 2383.80 387.40 19.40 11041.70 1658.40 17.67 mecha 2014 tesema 2014 2607.93 611.53 30.63 11705.57 2322.27 24.75 gudeta 2014 addis-01 2015 2662.60 666.20 33.37 11108.30 1725.00 18.38 meba 2016 axum 2016 diga-1 2016 2510.63 514.23 25.76 11104.65 1721.35 18.34 urji 2016 bako-09 2017 2694.20 697.80 34.95 12333.30 2950.00 31.44 jabi 2019 2563.30 566.90 28.40 11916.70 2533.40 27.00 overall increment 2445.43 449.03 22.49 10948.51 1565.21 16.68 note: gy = grain yield (kg ha–1); by = biomass yield (kg ha–1); and tadese and padet were the oldest varieties used as basis for trend analysis. table 3. temporal trends in mean grain and biomass yield of finger millet at finoteselam. variety year of release gy increment by increment mean (kg ha–1) (%) mean (kg ha–1) (%) tadese 1999 padet 1999 2033.80 – – 8428.15 – – boneya 2002 2486.60 452.80 22.26 9612.50 1184.35 14.05 degu 2005 2277.90 244.10 12.00 11311.30 2883.15 34.21 wama 2007 baruda 2007 2170.45 136.65 6.72 9075.00 646.85 7.67 bareda 2009 gutie 2009 2616.75 582.95 28.66 9928.15 1500.00 17.80 debatie 2010 2083.40 49.60 2.44 8718.80 290.65 3.45 necho 2011 2047.60 13.80 0.68 9675.00 1246.85 14.79 mecha 2014 tesema 2014 2412.27 378.47 18.61 10061.57 1633.42 19.38 gudeta 2014 addis-01 2015 2579.50 545.70 26.83 11962.50 3534.35 41.94 meba 2016 axum 2016 diga-1 2016 2453.93 420.13 20.66 10221.38 1793.23 21.28 urji 2016 bako-09 2017 2919.30 885.50 43.54 11635.40 3207.25 38.05 jabi 2019 2624.60 590.80 29.05 10260.40 1832.25 21.74 overall increment 2424.75 390.95 19.22 10223.82 1795.67 21.31 note: gy = grain yield (kg ha–1); by = biomass yield (kg ha–1); and tadese and padet were the oldest varieties used as basis for trend analysis. 3.2.2. progress on biomass yield, harvest index and plant height the analysis of variance revealed that biomass yield showed a highly significant difference among the varieties tested at both locations. moreover, the regression analysis revealed a significant positive association between biomass yield and year of variety release (tables 4 and 5). at adet, the overall increase in biomass yield over the oldest varieties was estimated to be 1565.21 kg ha–1 (16.68% year–1) and the estimated abunu et al. genetic gain in yield and related traits of finger millet 161 average annual rate of increase was 114.04 kg ha–1 year– 1 with an annual relative genetic change of 1.22% year– 1 (table 4). generally, the increment over 20 years was estimated to be 7.09% in 2002 and 27% in 2019 from the oldest varieties, tadese and padet released in 1999 (table 2). at finoteselam, the overall increase in biomass yield over the oldest varieties was 1795.67 kg ha–1 (21.31%) (table 3); and the estimated average annual rate of increase was 97.15 kg ha–1 year–1 with annual relative genetic change of 1.15% year–1 (table 5). accordingly, the increment over 20 years was estimated to be 14.05% in 2002 and 21.74% in 2019 from the oldest varieties (table 3). herewith, percentage of increment was higher for the varieties released in the year 2015 (41.94% or 3534.35 kg ha–1) and lower for the variety debatie (3.45% or 290.65 kg ha–1), which was released in the year 2010. from this result, it could be understood that there was a positive trend from the old to the latest varieties in biomass yield. this clearly indicates better genetic progress from breeding finger millet for biomass and grain yield than other traits except grain yield. similar findings were reported by wondimu fekadu et al. (2013) who found a significant annual increase in biomass yield for arley varieties released from 1973 to 2006. likewise, endashaw girma et al. (2019) reported that, biomass yield of bread wheat increased with ann annual rate of 17.469 kg ha–1 and a relative annual gain of 0.3%. fano dargo et al. (2016) reported that the average biomass yield of teff varieties increased by 73.74 kg ha–1 year–1. however, mekuria temtme (2017) found a negative trend from the old to the modern varieties in biomass yield of durum wheat varieties with relative annual biomass yield reduction of –0.00036% year–1 for 49 years. however, the progress showed a non-consistent trend of increment. this nonconsistent and downward trend of increment could be due to making the comparison among varieties recommended for varied agro-ecologies. the analysis of variance for harvest index also revealed very highly significant differences among the varieties and locations. however, regression analysis depicted a positive but non-significant increment with year of variety release, which was near zero. the annual change and relative genetic gain was 0.07% year–1 and 0.33% year–1 for adet and 0.01% year–1 and 0.04% year–1 for finoteselam (tables 4 and 5). from this result, it can be concluded that the grain yield to biomass ratio from oldest to newest varieties was not as such changed. the ratio of grain yield to biomass yield (harvest index) should be expected to increase. likewise, fano dargo et al. (2016) found unchanged annual change in harvest index, 0.02% which was not significantly different (p ≤ 0.05) from zero for teff. unlike harvest index, annual rate of change in plant height showed a negative trend, estimated to be –0.25 cm year–1 (–0.36% year–1) and –0.26 cm year–1 (–0.31% year–1) at adet and finoteselam, respectively (tables 4 and 5). this implies that, the varieties being released are becoming shorter in stature. in contrast to this result, fano dargo et al. (2016) found a non-significant increment in plant height for teff varieties. 3.2.3. progress on yield related traits at both locations, finger length and number of fingers per ear showed a positive but non-significant change with the year of variety release. thus, the annual rate of change in finger length was estimated to be 0.06 cm year-–1 (1.28% year–1) and 0.09 cm year–1 (1.96% year–1) at adet and finoteselam, respectively. fano dargo et al. (2016) also obtained positive but non-significant increment in panicle length of teff varieties. number of fingers per ear exhibited a non-significant positive change, 0.09 fingers year–1 (2.51% year–1) and 0.05 fingers year–1 (1.09% year–1) at adet and finoteselam, respectively. therefore, while doing selection, finger length and number of fingers per ear need to be considered as they have direct and positive correlation with grain yield. number of tillers per plant and ears per plant exhibited a highly significant change with the year of variety release. at adet, the regression analysis revealed that, the annual change in number of tillers per plant was 0.12 tillers plant-–1 year–1 (5.15% year–1) and ears per plat was 0.11 ears plant–1 year–1 (3.3% year–1), in the same order. at finoteselam, the change was 0.09 tillers plant–1 (3.96% year–1) and 0.09 ears plant–1 (2.75% year–1) (tables 4 and 5), indicating finger millet yield improvement involved increment in such parameters. similarly, michael kebede (2016) indicated the improvement made for ear length, kernels per row on maize. fano dargo et al. (2016) also found a significant change in panicle weight of teff varieties. in addition, mekuria temtme (2017) also found that, older varieties had lower number of grain per spike and productive tillers than the newer durum wheat varieties. thus, the progress made over years on most of the yield related traits of finger millet at both locations was inconsistent and non-significant, indicating that further breeding efforts have to be made to improve the productivity such traits as these traits have direct correlation with grain yield. abunu et al. east african journal of sciences volume 16(2): 155-170 162 table 4. estimates of relative genetic gain and regression coefficient of all traits with year of variety release at adet. trait overall mean mean of old varieties total rgg (%) rgg (% year–1) r2 (%) intercept regression coefficient (b) correlation coefficient r(by) r(gy) dh 102.13 101.00 1.12 –0.20 2.81 104.50 –0.20ns –0.12ns –0.28* dm 162.78 157.50 3.35 0.03 0.08 162.40 0.04ns –0.14ns –0.21ns gfp 60.65 56.50 7.35 0.42 12.63 57.78 0.24ns –0.06ns 0.08ns ph 71.04 69.60 2.07 –0.36 4.37 73.95 –0.25ns 0.35** 0.28* fl 7.02 4.70 49.36 1.28 2.37 6.35 0.06ns 0.16ns 0.09ns tpp 4.09 2.33 75.54 5.15 62.47 2.68 0.12** 0.56*** 0.60*** epp 5.04 3.33 51.35 3.30 57.20 3.71 0.11** 0.52*** 0.55*** fpe 5.72 3.58 59.78 2.51 15.73 4.61 0.09ns 0.25ns 0.25ns by 10807.00 9383.30 15.17 1.22 27.24 9466.66 114.04* – 0.88*** gy 2397.00 1996.40 20.07 1.55 40.00 2034.11 30.88** 0.88*** – hi 22.28 21.29 4.65 0.33 7.75 21.51 0.07ns –0.39** 0.08ns bpr 66.59 59.62 11.69 1.17 21.48 58.42 0.70* 0.96*** 0.87*** sgr 39.67 35.41 12.03 1.07 19.66 35.15 0.38* 0.85*** 0.89*** hb 15.65 19.63 –20.28 –0.71 0.38 17.28 –0.14ns –0.10ns –0.05ns note: *** = very highly significant at p ≤ 0.001; ** = highly significant at p ≤ 0.01; * = significant at p ≤ 0.05; and ns = non-significant. rgg = relative genetic gain (%); r(gy) = correlation coefficient of grain yield; r(by) = correlation coefficient of biomass yield; dh = days to 50% heading; dm = days to 50% maturity; gfp = grain filling period; ph = plant height (cm); fl = finger length (cm); tpp = tillers plant–1; epp = ears plant–1; fpe = fingers ear–1; by = biomass yield (kg ha–1); gy = grain yield (kg ha–1); hi = harvest index (%); bpr = biomass production rate (kg ha–1 day–1); sgr = seed growth rate (kg ha–1 day–1); and hb = head blast severity (%). r2 = coefficient of determination (%). abunu et al. genetic gain in yield and related traits of finger millet 163 table 5. estimates of relative genetic gain and regression coefficient of all traits with year of variety release at finoteselam. trait overall mean mean of old varieties total rgg (%) rgg (% year–1) r2 (%) intercept regression coefficient(b) correlation coefficient r(by) r(gy) dh 99.13 99.34 –0.21 –0.29 5.29 102.41 –0.29ns –0.30* –0.39** dm 155.92 148.17 5.23 0.07 0.78 154.72 0.10ns –0.21ns –0.36** gfp 56.78 48.84 16.26 0.78 21.10 52.31 0.38* 0.13ns 0.08ns ph 80.90 83.53 –3.15 –0.31 3.68 84.00 –0.26ns 0.04ns 0.19ns fl 7.79 4.59 69.72 1.96 6.64 6.78 0.09ns 0.25* 0.10ns tpp 3.34 2.27 47.14 3.96 49.44 2.29 0.09** 0.56*** 0.54*** epp 4.34 3.27 32.72 2.75 49.15 3.28 0.09** 0.56*** 0.54*** fpe 5.84 4.60 26.96 1.09 10.19 5.26 0.05ns 0.23ns 0.16ns by 9955.00 8428.15 18.12 1.15 24.43 8813.89 97.15* – 0.79*** gy 2386.00 2033.80 17.32 1.20 28.82 2099.06 24.39* 0.79*** – hi 24.13 24.21 –0.33 0.04 0.06 24.05 0.01ns –0.53*** 0.09ns bpr 64.05 56.89 12.59 1.05 17.73 56.96 0.60ns 0.97*** 0.82*** sgr 42.29 41.70 1.41 0.41 3.23 40.31 0.17ns 0.62*** 0.82*** hb 26.71 28.33 –5.72 –0.64 0.55 28.85 –0.18ns –0.04ns –0.13ns note: *** = very highly significant at p ≤ 0.001; ** = highly significant at p ≤ 0.01; * = significant at p ≤ 0.05; and ns = non-significant. rgg = relative genetic gain (%); r(gy) = correlation coefficient of grain yield; r(by) = correlation coefficient of biomass yield; dh = days to 50% heading; dm = days to 50% maturity; gfp = grain filling period; ph = plant height (cm); fl = finger length (cm); tpp = tillers plant–1; epp = ears plant–1; fpe = fingers ear–1; by = biomass yield (kg ha–1); gy = grain yield (kg ha–1); hi = harvest index (%); bpr = biomass production rate (kg ha–1 day–1); sgr = seed growth rate (kg ha–1 day–1); and hb = head blast severity (%). r2 = coefficient of determination (%). abunu et al. east african journal of sciences volume 16(2): 155-170 164 3.2.4. progress on biomass production rate and seed growth rate the analysis of variance for biomass production rate and seed growth rate depicted highly significant differences (p < 0.001) among the tested varieties (table 1). most of the recently released varieties provide a higher biomass production rate and seed growth rate than the older varieties at both locations (tables 4 and 5). at adet, both biomass production rate and seed growth rate increased significantly (p < 0.05) with the year of variety release with annual genetic gain of 0.7 kg ha–1 day–1 year–1 and 0.38 kg ha–1 day–1 year–1, respectively. moreover, the relative annual gains were 1.17% year–1 for biomass production and 1.07% year–1 for seed growth (table 4). at finoteselam, all of the productivity traits showed positive but nonsignificant increment with the year of variety release with annual change of 0.6 kg ha–1 day–1 year–1 (1.05% year–1) and 0.17 kg ha–1 day–1 year–1 (0.41% year–1) for biomass production rate and seed growth rate, respectively (table 5). similarly, fano dargo et al. (2016) reported a significant increase (p ≤ 0.01) in biomass production rate on the tested teff varieties. this result implies that substantial improvement was apparent but was not as such ample, suggesting further breeding efforts as productivity traits are indications of efficiency of giving high biomass and grain growth within a short growing period. 3.2.5. progress on phenological traits the analysis of variance revealed that, both days to heading, days to maturity and grain filling period had significant differences (p ≤ 0.01) among locations and varieties (table 1). moreover, regression analysis at both locations revealed that, days to heading showed a negative trend over 20 years, meaning that the varieties being released currently are somewhat early in heading. the annual rate of change in days to heading was estimated to be –0.2 days year–1 (–0.2% year–1) and – 0.29 days year–1 (–0.29% year–1) at adet and finoteselam, respectively. however, the annual rate of change in days to maturity was positive and near to zero, 0.04 days year–1 (0.03% year–1) and 0.01 days year– 1 (0.07% year–1) at adet and finoteselam, respectively. grain filling period also showed a bit increment. thus, rate of change was estimated to be 0.24 days year–1 (0.42% year–1) and 0.38 days year–1 (0.78% year–1) at adet and finoteselam, in that order (tables 4 and 5). likewise, wondimu fekadu et al. (2013) reported that phenological traits showed a non-significant decreasing trend in food barely. despite small progress made on days to heading (ryear = –0.2ns at adet and ryear = –0.29ns at finoteselam), the change was not significant in grain filling period and days to maturity (tables 4 and 5). therefore, changes are still required because the changes obtained were non-significant. as a result, the varieties to be released in the future should be early maturing by comparing the standard checks since earliness is a major concern for finger millet. this is because finger millet is a late maturing crop as compared to other cereals, and sometimes it is exposed to terminal moisture and cannot leave the farming area for the next cropping season. 3.2.6. progress on blast disease reaction the analysis of variance for head blast susceptibility depicted significant (p < 0.001) differences among the varieties and locations. the susceptibility of the varieties was higher at finoteselam, which might be due to the more prevalence of blast disease in the area since it has higher temperature and humidity. among the tested varieties, a small change was observed from the oldest to the newest varieties. regression analysis showed a positive relationship in variety release and disease susceptibility, implying reductions in percentage of head blast susceptibility even though the change was not significant. thus, the annual rate of change and relative genetic gain was –0.14% year–1 and –0.71% year–1 at adet, and –0.18% year–1 and –0.64% year–1 at finoteselam (tables 4 and 5), indicating some sort of reduction in percentage of blast infection (increasing in disease resistance of the released varieties with respective of year of release). similarly, tamene temesgen et al. (2015) reported that, annual rate of reduction in chocolate spot severity was –0.27% year–1; and relative genetic gain was –0.65% year–1. despite the progress made, the change obtained was not significant at both locations (tables 4 and 5). in spite of its importance, the current rate of yield increment in finger millet is inadequate in ethiopia. although a number of biotic and abiotic factors contributed to the lower grain yield increment, blast is considered as one of the major biotic factors impeding finger millet productivity in ethiopia. in line with this postulation, dagnachew lule et al. (2013) reported, an average of 42% of finger millet grain yield was lost due to blast disease in ethiopia. similarly, finger millet yield loss because of blast disease was 41.8% (gashaw getachew et al., 2014). therefore, this limitation can be reduced by developing finger millet genotypes which are more resistant or tolerant to blast. thus, finger abunu et al. genetic gain in yield and related traits of finger millet 165 millet breeders should give due attention to develop blast resistant/tolerant varieties as this disease is a serious cause of loss of yield. 3.3. traits correlated with yield improvement at adet, grain yield had a significant genetic correlation with biomass yield, biomass production rate, seed growth rate, number of tiller per plant, but had a nonsignificant positive correlation with grain filling period, plant height, finger length, number of ears per plant, number fingers per ear, and harvest index. however, grain yield had a non-significant negative correlation with days to heading, days to maturity and head blast susceptibility (table 6). at finoteselam, grain yield also had positive significant correlation with biomass yield, biomass production rate, seed growth rate, number of tiller per plant, number of ears per plant; but had a nonsignificant positive correlation with grain filling period, plant height, finger length, number fingers per ear, and harvest index. however, grain yield had significant negative correlation with days to heading; and nonsignificant correlation with days to maturity and head blast susceptibility (table 6). likewise, molla fentie (2012) found a significant correlation of grain yield with biomass yield. devaliya et al. (2017) also reported a highly significant genotypic correlation of grain yield with number of productive tillers per plant and negative correlation with phenological traits. similarly, negative and significant correlation between grain yield and days to maturity was reported by kebere bezaweletaw et al. (2006) in finger millet. likewise, positive correlations were reported between grain yield and productive tillers and between plant height and finger length (chemeda daba and gemechu keneni, 2010). in contrast to the present result, a significant and positive correlation was observed for grain yield with days to maturity (chemeda daba and gemechu keneni, 2010). tazeen et al. (2009) also reported that, grain yield was positively correlated with biomass and harvest index. moreover, these results are in accordance with the findings of ganapathy et al. (2011), anuradha et al. (2013), abhinav et al. (2016) and chavan et al. (2020) on finger millet. this suggests selecting for the trait with high positive correlation would improve the grain yield of respective crop. in addition, nandini et al. (2010) found correlation of grain yield with plant height and tiller number on finger millet, which is in agreement with the preset result. this can be due to the increase in finger length that increases with plant height. moreover, plant height was negatively correlated with phenological traits; meaning that, it is not always true that plant height increased as the number of days to mature increased. among the tested varieties, most of the shortest varieties were late maturing because these varieties were released for midlowland areas and the current site was somewhat highland. in line with this, andualem wolie and tadesse dessalegn (2011) reported a negative genotypic correlation of plant height with days to maturity. generally, the present study at both locations revealed that, the type and number of yield related traits correlated with grain yield was almost the same except the magnitude of correlation. the strongest positive correlation with grain yield was observed by biomass yield, biomass production rate, seed growth rate, number of tillers per plant and number of ears per plant. the existence of strong correlation is the indications of those traits which are conditioned by linked gene, be it in the positive or negative direction. consequently, selection for one trait can indirectly introduce changes in the other trait in positive or negative direction due to either genetic linkage or presence of pleiotropic gene effect or both (falconer, 1989). therefore, the overall increment of grain yield over 20 years was associated with improvements with these significantly correlated traits. as a result, these traits will serve as a selection criterion as they are correlated and improved with grain yield. however, the strongest negative correlation was observed for days to maturity and days to heading, implying an opportunity to develop relatively early maturing varieties with better yield potential. most of the varieties tested were late in maturity, which required an average of 160 days to mature (table 1). even though the present experiment was conducted in the areas where moisture stress was not much prevalent, the growing period for finger millet varieties should not be so long. this is because early maturity is advantageous to escape terminal moisture stress as well as to leave the farm for the next cropping. abunu et al. east african journal of sciences volume 16(2): 155-170 166 table 6. genotypic correlation coefficients of traits of the tested finger millet varieties at adet (above diagonal) and finoteselam (below diagonal). trait dh dm gfp ph fl tpp epp fpe by hi bpr sgr hb gy dh – 0.86*** –0.11ns –0.36ns 0.01ns –0.12ns –0.13ns 0.33ns –0.16ns –0.37ns –0.40ns –0.25ns –0.33ns –0.32ns dm 0.76*** – 0.42ns –0.37ns 0.14ns 0.10ns 0.09ns 0.39ns –0.18ns –0.14ns –0.47* –0.43ns –0.34ns –0.24ns gfp –0.41ns 0.29ns – –0.09ns 0.24ns 0.40ns 0.41ns 0.16ns –0.06ns 0.38ns –0.21ns –0.39ns –0.08ns 0.11ns ph –0.38ns –0.65** –0.34ns – 0.49* 0.00ns –0.02ns 0.02ns 0.35ns –0.15ns 0.41ns 0.29ns 0.37ns 0.27ns fl 0.11ns 0.42ns 0.42ns –0.22ns – 0.23ns 0.25ns 0.72* 0.07ns –0.09ns 0.02ns –0.09ns 0.68** 0.01ns tpp –0.36ns –0.07ns 0.44ns –0.15ns 0.28ns – 0.99** 0.43ns 0.37ns 0.30ns 0.30ns 0.30ns –0.12ns 0.51* epp –0.36ns –0.07ns 0.44ns –0.16ns 0.28ns 0.99*** – 0.41ns 0.30ns 0.30ns 0.25ns 0.23ns –0.11ns 0.44ns fpe 0.32ns 0.50* 0.23ns –0.33ns 0.77* 0.22ns 0.22ns – 0.12ns 0.06ns 0.00ns 0.07ns 0.46* 0.14ns by –0.37ns –0.26ns 0.18ns 0.30ns 0.20ns 0.58** 0.58** 0.10ns – –0.19ns 0.95*** 0.86*** –0.12ns 0.89*** hi –0.09ns –0.20ns –0.15ns 0.18ns –0.24ns –0.12ns –0.12ns –0.08ns –0.38ns – –0.14ns 0.06ns 0.13ns 0.27ns bpr –0.53* –0.52* 0.05ns 0.45* 0.05ns 0.53* 0.53* –0.05ns 0.96*** –0.27ns – 0.91*** 0.00ns 0.87*** sgr –0.13ns –0.53* –0.55* 0.58** –0.23ns 0.17ns 0.16ns –0.09ns 0.54* 0.32ns 0.65** – –0.02ns 0.87*** hb –0.41ns –0.17ns 0.35ns 0.04ns 0.58** 0.07ns 0.07ns 0.38ns –0.04ns –0.12ns 0.00ns –0.32ns – –0.08ns gy –0.45* –0.41ns 0.09ns 0.43ns 0.03ns 0.51* 0.51* 0.05ns 0.77*** 0.30ns 0.80*** 0.78*** –0.13ns – note: *** = very highly significant at p ≤ 0.001; ** = highly significant at p ≤ 0.01; * = significant at p ≤ 0.05 and ns = non-significant. dh = days to 50% heading; dm = days to 50% maturity; gfp = grain filling period; ph = plant height (cm); fl = finger length (cm); tpp = tillers plant–1; epp = ears plant–1; fpe = fingers ear–1; by = biomass yield (kg ha–1); hi = harvest index (%); bpr = biomass production rate (kg ha–1day–1); sgr = seed growth rate (kg ha–1day–1); hb = head blast severity (%); and gy = grain yield (kg ha–1). abunu et al. genetic gain in yield and related traits of finger millet 167 stepwise regression analysis using grain yield as dependent variable indicated that, biomass yield and harvest index were the most important traits which greatly contributed most of the variation on grain yield, 99.74% at adet and 99.42% at finoteselam (table 7). therefore, it can be considered that changes obtained had probably contributed to the changes in grain yield during the last 20 years of finger millet breeding. similarly, wondimu fekadu et al. (2013) reported that, harvest index, biomass yield and biomass production rate were traits contributed to gain in grain yield of food barley varieties. in general, grain yield in the latest varieties appears to be associated more with the production of a higher biomass, indicated biomass yield may serve as an index for identifying and improving finger millet varieties. hence, it is of vital importance to give due attention to biomass yield and other significantly correlated traits while selecting finger millet lines for future improvement. table 7. stepwise regression analysis of grain yield on selected yield components. adet independent variable intercept regression coefficient (b) partial r2 (%) r2 (%) biomass yield –2105.05 0.22*** 79.36 79.36 harvest index 95.91*** 20.38 99.74 finoteselam biomass yield –2478.11 0.24*** 58.79 58.79 harvest index 103.22*** 40.63 99.74 note: *** = very highly significant at p < 0.001. r2 = coefficient of determination (%). 4. conclusion and recommendation the results of this study have demonstrated a substantial progress in the plant breeding work executed for improving the productivity of finger millet in the last 20 years. stepwise regression analysis revealed that biomass and harvest index accounted for 99.74% of the variation on grain yield at adet and 99.42% at finoteselam. the results indicated that the yield gain was largely obtained through increased biomass and harvest index. these traits can be considered as the selection criteria for the improvement of finger millet grain yield since they exhibited a strong positive correlation. even though changes have been made on grain yield, biomass yield and some important traits, the changes made on most of the traits were non-significant. therefore, to bring drastic changes in most important traits like head blast resistance, earliness, finger length, number of fingers per ear and number of ears per plant, appropriate breeding strategies should be devised for future 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urban expansion, displaced households 1. introduction the level of urbanization in africa is low (37.1%) compared to that of the developed countries like europe (72.7%) and north america, 79.1% (united nations, 2014). however, urbanization in the developing world is progressing much faster than the developed countries, which may reach 4% a year (world bank, 2014). in support of these, marshall et al. (2013) indicated that the fast rate of urbanization in the developing world is attributed to rural-urban migration, economic growth, technological change, and rapid population growth. the number of urban residents in africa has been growing since the 1950s, hitting 40% of the continent’s total in mailto:zelalemgebeyehu1936@gmail.com zelalem et al. east african journal of sciences volume 16(2): 187-198 188 2018 and is projected to reach 56% by 2050 (undesa, 2018). studies conducted in africa revealed that urbanization is directly or indirectly associated with informal settlements and working environments (naab et al., 2013; world bank, 2015). it further relates with limited job creation, weak linkages with rural areas, and low levels of productivity (tacoli, 2012; henderson et al., 2013). even more, studies indicated that recent urban expansions in sub-saharan africa lack adequate investments and required degree of industrialization (henderson et al., 2013; jedwab et al., 2014). this implies that the bottom poor households may gain little from rising urbanization and hence the latter can increase income inequality in the short to medium term (kanbur and zhuang, 2013). these patterns are consistent with the widening income gaps in some of the countries experiencing rapid urban expansion process. for instance, in the context of ethiopia, the urban income inequality-with a gini coefficient of 0.38 is higher than the rural income inequality -with a gini coefficient of 0.28 (csa, 2019). the history of urbanization in ethiopia traces back to thousands of years and include such iconic urban settlements, namely, aksum, lalibela, and gondar. however, the country has low level of urbanization even by african standards, where only 19% of the population lives in the urban area (addisyihun abayneh, 2019). however, ethiopia started to record a relatively high growth rate of urban population (4% annually), double that of rural areas in recent years (undp, 2015). some estimates indicate that ethiopia's urban population will increase three times in the next 20+ years, achieving an extreme urban growth rate of over 5% per year. furthermore, the country's urban population is expected to grow on average by 3.98% by 2050, about 42.1% of the total population is expected to be reside urban centers (un-habitat, 2017). in ethiopia, the growth of the urban population has required an enormous amount of land resources necessary for housing services, and infrastructural development (achamyeleh gashu, 2016; kassahun tassie, 2018). as a result of population pressure, cities have expanded horizontally towards pre-existing rural villages to satisfy the huge demand for urban land (addisu mera, 2015; gadisa worku, 2019).on the other hand, the land is a very important and scarce asset to farm households (dfdi, 2013). however, peri-urban farm households loose land forever due to urban-driven expansion processes (achamyeleh gashu, 2014; abubeker mohammed, 2018). studies conducted on urbanization expansion in ethiopia showed that urban expansion results in displacement, eviction, and segregation of urban neighbors in general and neighboring farmers in particular that result in social makeup disorder (unpfa, 2007; leulseged kassa et al., 2011; muluwork zebu, 2014; tsega gebrekristose, 2014; addisu mera, 2015; teketel fekadu, 2015; idris mohammed et al., 2020). moreover, rapid urban growth and building new urban houses each year puts continued pressure on the livelihoods of original peri-urban farming dwellers. the above researchers used income as a parameter to show the impacts of urban expansion on the livelihoods of peri-urban farming dwellers, which is only one indicator and is not comprehensive. measuring income also requires formal recording or recalling long-term data. at the same time, evicted farmers are wary of giving real data on income and they decrease their income when reporting hoping that they would be eligible to receive foreign aid such as usaid. hence, consumption-based inequality measurements are relatively more reliable than incomebased measurements. moreover, there is little information about the extent of expenditure inequality incidence among peri-urban farm households as a result of urban induces displacement. unprecedented growth of the urban population in metropolitan towns of the amhara national regional state of the country have resulted in high demands of urban land for residential housing, service provision, and infrastructure development. for instance, the population of bahir dar increased from 54,800 in 1984 to 96,140 in 1994 with an average growth rate of 5.6%. in 2007, the population of the town increased to 155,428 with an average growth rate of 3.7% and it reached 226,713 in 2014 and 350,000 in 2017. likewise, the population of gondar town increased from 80,886 in the year 1984 to112, 249 in 1994 with an average growth rate of 3.3%; and it reached 207,044 in 2007 with an average growth rate of 4.7% the population of gondar town reached 315 856 in 2018. the other metropolitan town, dessie, has also experienced a fast-growing urban population. for example, in the year 1984, the town’s population was 68,848 and in 1994, it turned out to be 97,314 with an average growth rate of 3.5%. in 2007, the population of the town reached 120,095 with an average growth rate of 1.6 the population of the town reached 219,726 in 2018 (bofed, 2014; mudhco and ecsu, 2015; csa, 2018). zelalem et al. consumption inequality incidence of peri-urban farm households 189 hence, these population pressures caused horizontal expansion of towns. to satisfy the huge demand for urban land, metropolitan towns of the region have been incorporating the pre-existing rural villages into urban areas. as a result, the local inhabitants of the farmlands lying near the towns often dispossessed from their farmlands with meager compensations. according to amhara national regional state urban development, housing and construction bureau (2017), about 3,053.12 hectares of agricultural land expropriated from above 1500 peri-urban farmers and transferred to 129,594 urban residents through the lease system. in ethiopia, land acquisition and delivery for urban expansion and development purposes are completely state-controlled (fdre, 1995). farmers affected by urban expansion processes have the right to receive compensation (fdre, 2008). however, rehabilitation mechanisms used by the towns’ administrations constituting mainly arrangements of cash payments as compensation found to be inadequate to replace the resource bases lost by the displaced farm households, which is mainly land (idris mohammed et al., 2020). displaced farm households may not be able to buy another plot of land to continue their farming activities because of the country’s land policy. hence, they start to look for alternative employment opportunities other than crop and livestock production. therefore, the objective of this study was to investigate the inequality in consumption expenditures prevailing among displaced and non-displaced farm households in selected towns of amhara national regional state, ethiopia. in this perspective, a question posed in this study as to whether urban expansion brings significant consumption expenditure inequality among displaced and non-displaced farm households in the peri-urban areas. the study on urban expansion in less developed countries like ethiopia are issues that look for a solution from scholars for making the government and policy makers aware about the adverse consequences of urban expansion and forward a set of priorities and alternative policies that can protect the original peri-urban farm households as a result of urban expansion-induced displacement. 2. methodology of the study 2.1. description of the study area the study was conducted in the metropolitan towns of the amhara national regional state (gondar, bahir dar, and dessie). bahir dar town, which is located on the southern shore of lake tana, the source of the blue nile (abay) river, has a long history dating back to at least the sixteenth or seventeenth century. it is currently the capital of the amhara national regional state, which is located in the northwestern part of ethiopia (bofed, 2014). the town is located at 11o36' north latitude and 37o23' east longitudes. it has an average elevation of 1,801meters above sea level (ethiopian mapping agency, 1981). on the other hand, dessie town is located on the addis ababa-mekelle highway, at a distance of about 401 km from addis ababa, in the northern part of the country in the south wollo administrative zone of the amhara national region state. this town is located at 11'8° north latitude and 39'38° east longitude and at an average elevation of 2470 meters above sea level (ethiopian mapping agency, 1981). the other metropolitan town, gondar, which is the capital of the central gondar zone, is located at the distance of about 738 km from addis ababa and 182 km from bahir dar in the north or northwesterly direction. it is located at 12o30' north and 37o20' east and an average elevation of 2133 meters above sea level (ethiopian mapping agency, 1981). zelalem et al. . east african journal of sciences volume 16(2): 187-198 190 figure 1. map of the study areas 2.2. sampling technique and sample size a multistage sampling procedure was employed to draw representative sample households for the study. in the first stage, three towns in the amhara national regional state (bahir dar, dessie, and gondar) were purposively selected. the towns represent the major urban expansion features and are the capitals of zones in the amhara national regional state. in the second stage, peri-urban kebeles (the lowest administrative unit in ethiopia) were identified from the respective towns’ administration. there are 14, 6, and 11 peri-urban kebeles in bahir dar, dessie, and gondar towns, respectively. therefore, seven pre-urban kebeles (3, 2, and 2 from bahir dar, dessie, and gondar towns) were selected based on the mean value of the number of displaced farmers in all metropolitan cities. those kebeles, which have high displacement above the mean values, were selected purposively. this is because to consider peri-urban kebeles with the high number of displacements. in the third stage, households’ lists in the selected kebeles obtained from each kebele’s administration. the list was stratified into displaced and non-displaced farmers. the final sampling procedure was to select displaced and non-displaced farm households' heads. from seven peri-urban kebeles, 430 (183 displaced and 247 non-displaced) farm households were selected randomly based on the proportions in the population. the total required sample size was determined using kothari (2004) formula: 𝑛 = 𝑧2 × 𝑝 × 𝑞 × 𝑁 𝑧2 × 𝑝 × 𝑞 + (𝑁 − 1) ⥂ 𝑒 2 − −(1) where, n is the desired sample size; 𝑍 is the standard cumulative distribution ((z = 1.96 for 95% confidence level); e is the desired level of precision (e = 5% or 0.05); p proportion of target population to the total population of kebeles; q = 1-p; and n is the total number of households from which the sample is drawn. table 1. number of sample households from each peri-urban kebeles. city peri-urban kebeles population displaced sampled households total displaced non-displaced bahir dar zenzelima 9,282 1338 27 34 61 meshenti 8,219 1193 24 30 54 adisalem 7,510 1047 21 28 49 dessie boru 3,319 512 10 12 22 tita 4,727 680 14 17 31 gondar blajig 7,909 945 19 33 52 azezo t/haymanot 24,419 3345 68 93 161 total 65,385 9060 183 247 430 zelalem et al. consumption inequality incidence of peri-urban farm households 191 2.3. methods of data analysis measurement of inequality was made based on the level of real consumption expenditure per adult equivalent of the household to capture consumption differences by age and economies of scale. consumption expenditure data were preferred for the reason that it was more reliable and simple to compute than income (deaton, 1997; dercon, 2005; duclos and araar, 2006). thus, consumption expenditure was taken as a proxy variable for income or to measure inequality. hence, deciles ratio, gini coefficient, and generalized entropy inequality indices were employed to measure consumption inequality among displaced and non-displaced farm households. i. deciles ratio deciles ratio divides the population into successive deciles according to ascending consumption expenditure levels and then determines the proportion of net expenditure received by each group. the deciles dispersion ratio presents the ratio of the average expenditure or income of the richest 10% of the population divided by the average expenditure of the bottom 10%. this ratio is readily interpretable by expressing the expenditure of the rich as multiples of that of the poor. ii. gin coefficient gini coefficient is the most common indicator for measuring inequality in household consumption. it computes the average distance between the cumulated population shares and cumulated consumption shares. in other words, it the ratio of the area between the lorenz curve and the diagonal equality line to the total area of the triangle (world bank, 2005; fekadu gelaw, 2009). the standard gini index is thus given by: 𝐺𝑖𝑛𝑖 = 2𝑐𝑜𝑣(𝑌, 𝐹) �̅�⁄ − − − − − − − (2) where, y is the consumption of the individual or household; f is the rank; and �̅�is the mean consumption. iii. generalized entropy class (ge) one of the most frequently used inequality measures for decomposition purpose is the general entropy class of measures introduced by cowell (1980) which is defined as: 𝐺𝐸(𝛼) = 1 𝛼(𝛼−1) [ 1 𝑛 ∑ ( 𝑦𝑖 𝑦 ) 𝛼 − 1𝑛 𝑖=1 ] α = 0, 1 – – (3) 𝐺𝐸(𝛼) = [ 1 𝑛 ∑ 𝑙𝑜𝑔 ( 𝑦 𝑦𝑖 )𝑛𝑖=1 ] α = 0 𝐺𝐸(𝛼) = [ 1 𝑛 ∑ 𝑦𝑖 𝑦 𝑙𝑜𝑔 ( 𝑦𝑖 𝑦 )𝑛𝑖=1 ] α = 1 𝐺𝐸(𝛼) = [ 1 𝑛𝑦2 ∑ (𝑦𝑖 − 𝑦) 2𝑛 𝑖=1 ] α = 2 where, 𝑦𝑖 is the expenditure of the i th household; y is the mean expenditure; and α is the distributional parameter. as the value to of α approaches to zero, the ge class is more sensitive to changes at the lower end of the distribution and equally sensitive to changes across the distribution for α equal to one (which is the thiel index) and sensitive to changes at the higher end of the distribution for higher values (foster, 1984). the ge class has important advantages: first, ge can be decomposed into withinand between-group inequality over space and time. the within-group inequality shows how much of the overall inequality attributed due to the change in consumption distribution within the group taking the group as a population. the between-group inequality index helps to examine how much of the overall inequality is due to changes in the mean consumption of each group by assuming all members in the group consume the average amount equally. second, different entropy class of measures is sensitive to different parts of the distribution (world bank, 2005). the total inequality obtained above can be decomposed into a component of inequality between the population groups 𝐼𝑏 and the remaining within group inequality 𝐼𝑤 . the decomposition by population group at a point in time of the ge class is defined as follows: 𝐼 = 𝐼𝑏 + 𝐼𝑤 = ∑ 𝑉𝑗 𝛼 𝑓𝑗 1−𝛼𝑘 𝑗 𝐺𝐸(𝛼)𝑗 + 1 𝛼2−𝛼 [∑ 𝑓𝑗 ( 𝑦𝑛 𝑦 ) 𝛼 − 1𝑘𝑗 ] – – – – – – – – – – – – – (4) where, 𝑓𝑗 is the population share of group j (j = 1, 2, …, k); 𝑉𝑗 is the consumption share of group j; and 𝑦𝑗 is the average income in groups j. 3. results and discussion 3.1. demographic and socioeconomic characteristics of sample households the average ages of displaced and non-displaced farm households were 47.2 and 47.38 years, respectively. the youngest and oldest respondents were respectively, 32 and 78 years old. the survey result also indicated the average education levels of displaced and non-displaced zelalem et al. east african journal of sciences volume 16(2): 187-198 192 farmers were 3.40 and 3.60 years, respectively. the test statistics showed that there were no significant differences among the displaced and non-displaced farm households in terms of age and education level (table 2). the average dependency ratios for displaced and nondisplaced farm households were about 1.18 and 0.5 respectively. the survey result showed that there was a statistically significant mean difference between the displaced and non-displaced groups in terms of dependency ratio at a 1% probability level (table 2). the mean landholding sizes for the non-displaced and displaced sample households were found to be 0.83 and 0.22 hectares per head respectively. the statistical analysis showed that there was a significant difference at a 1% probability level in the mean landholding size between displaced and non-displaced farm households. this indicates that displaced farm households’ landholding size significantly reduced as compared to that of the nondisplaced farm households because of the urban-induced expansion. similarly, the mean livestock holding of non-displaced and displaced farm households in the study area were 4.85 and 1.24 tropical livestock units (tlu) respectively. the survey result demonstrated that the mean significant differences between livestock holding among nondisplaced and displaced farmers were statistically significant at a 1% level of probability (table 2). the implication is that displaced farm household’s livestock holding reduced as compared to non-displaced farm households. this is because the grazing land of the area decreased because of urban-induced displacement. table 2. demographic and socioeconomic characteristic of the households. variable displaced (n = 183) non-displaced (n = 247) t-value total (n = 430) mean st. dev. mean st. dev. mean st. dev. min. max. age 47.20 10.04 47.38 10.45 0.178 47.3 10.27 32 78 education 3.40 3.085 3.60 3.19 0.652 3.51 3.14 0 12 dependency ratio 1.18 0.55 0.50 0.51 –13.1*** 0.79 0.63 0 2 land size(ha) 0.22 0.14 0.83 0.29 26.37*** 0.57 0.38 0 1.75 livestock(tlu) 1.24 1.28 4.85 1.98 21.47*** 3.31 2.48 0 13 note: st. dev. = standard deviation; min. = minimum; and max. = maximum. *** refers to statistical significance at 1% probability level. the survey results in table 3 shows that out of the total 183 samples displaced farm households, 133(72.68%) critically criticized the amount of compensation given from the respective city administrations. the rationale behind their criticism is that the amount of compensation did not match with the current value of land for the fact that the lease prices of the same plot of land in the city administration are much higher than their respective compensation rate. the households believed that the amounts of compensation were decided subjectively. similarly, the survey results showed that 69.4% of displaced farm households used land compensation for consumption purpose only while only 30.6% of displaced farm households utilized the compensation for further asset generating activities. table 3. descriptive statistics on displaced farm households land compensation. variable displaced farm households (n = 183) number % utilization compensation production 56 30.60 consumption 127 69.40 un-fair and in-adequate monetary compensation no 50 27.32 yes 133 72.68 zelalem et al. consumption inequality incidence of peri-urban farm households 193 3.2. descriptive statistics on consumption expenditure by displacement status household consumption expenditure consists of expenses on all food and non-food items. the aggregate of these components provided a measure of total annual household consumption expenditure during the past 12 months. quantities consumed and their prices were critical information for this research. the average current market prices for each item in the basket based on local prices data in 2019/2020 used to convert annual household expenditure to etb. hence, expenditure/per adult/annum is calculated by summing up all the expenditure components and dividing by the total adult equivalent of the household. the mean values of consumption expenditures per adult equivalent by displacement status were given in table 4 below. table 4. descriptive statistics on consumption expenditure by displacement status. variables displaced (n = 183) non-displaced ( n = 247) t-value difference (n = 430) mean st. dev. mean st. dev. mean std. err. food expenditure 4497.75 3012.61 6930.91 2490.35 9.2*** 2433.16 265.75 non-food expenditure 1439.17 1472.37 5735.06 2541.39 20.5*** 4295.89 209.96 total expenditure 5936.92 4250.28 12665.96 5021.88 14.7*** 6729.04 459.32 note: *** refers to statistical significance at 1% probability level. survey result in table 4 above indicated on average, the annual food expenditure per adult equivalent for displaced and non-displaced households had been etb 4497.75 and 6930.91, respectively. on the other side, annual non-food consumption expenditure per adult equivalent of displaced and non-displaced households were 1439.17 and 5735.06 ethiopian birr respectively with a mean difference significant at a 1% probability level. moreover, the average total consumption expenditure per adult equivalent for displaced farm households was 5936.92 etb. it was lower than the average total consumption expenditure per adult equivalent of non-displaced farm households etb 12665.96 with a mean difference significant at 1% probability level (table 4).this indicates that various asset bases of displaced farm households that were important for their livelihood diminished drastically over time, which implied that their consumption expenditure also reduced. 3.3. consumption expenditure distribution among peri-urban farm household the total consumption expenditure per adult equivalent distribution differentiated among displaced and nondisplaced farm households (table5). the results confirm the presence of extreme expenditure inequality among peri-urban farm households in the metropolitan towns of amhara national regional state by showing that 2.7% of displaced farm households consumption expenditure per adult equivalent accrues to those in the top deciles (3 displaced farm households). the bottom 10% (42) displaced farm households comprised just 35 percent of the total consumption expenditure per adult equivalent. the results further show that displaced farm households’ total sum of consumption expenditure per adult equivalent in the first deciles is about 515051.88 etb. about 0.7% of non-displaced farm households’ consumption expenditure share exists in the bottom deciles (1 non-displaced farm households). similarly, nondisplaced farm households’ total sum of consumption expenditure per adult equivalent in the top deciles is about 575151.11 etb. on the other hand, about 21% of nondisplaced farm households' consumption expenditure share exists in the top deciles. it is evident from table 5 that a large segment of the displaced farm households appears to be concentrated in the bottom deciles while the non-displaced farm household's population is concentrated in the top deciles. hence, urban expansion induced displacement is widening consumption expenditure gaps among displaced and non-displaced farm households in the study area. zelalem et al. east african journal of sciences volume 16(2): 187-198 194 table 5.consumption expenditure distribution by displacement status. expenditure deciles non-displaced ( n = 247) consumption expenditure/ae displaced (n = 183) consumption expenditure/ae total (n = 430) consumption expenditure/ae first number 1 42 43 sum 17932.03 515051.88 532983.91 share 0.7% 35% 12.6% second number 5 38 43 sum 71246.06 105102.49 176348.55 share 2.6% 7.1% 4.2% third number 11 32 43 sum 21564.32 63828.81 85393.13 share 0.8% 4.3% 2.0% fourth number 25 18 43 sum 291412.51 173956.40 465368.91 share 10.6% 11.8% 11.0% fifth number 28 15 43 sum 248844.95 137117.63 385962.59 share 9.1% 9.3% 9.2% sixth number 32 11 43 sum 276562.82 86446.46 363009.28 share 10.1% 5.9% 8.6% seventh number 33 11 44 sum 262121.18 168647.23 430768.41 share 9.6% 11.5% 10.2% eighth number 34 8 42 sum 504063.40 112588.48 616651.88 share 18.4% 7.6% 14.6% ninth number 38 5 43 sum 473681.49 69415.55 543097.04 share 17.3% 4.7% 12.9% tenth number 40 3 43 sum 575151.11 40213.68 615364.79 share 21% 2.7% 14.6% 3.4. inequality indices the gini coefficient calculated based on farm households’ consumption expenditure per adult equivalent for all the sampled farm households was 0.4858. the gini index of consumption expenditure per adult equivalent inequality value suggests that expenditure inequality of peri-urban farm households was higher in metropolitan cities of amhara national regional state. the values for the deciles dispersion ratio, which presents the ratio of the average consumption of expenditure per adult equivalent of the richest 10% of the population divided by the average consumption expenditure per adult equivalent of the bottom 10%. therefore, one can easily infer that the richest 10% of households consume 1.155 times more than the poorest 10% of households (table 6). this distribution indicates there was a huge gap in consumption expenditure per adult equivalent among the peri-urban farm households. the survey results revealed that the general entropy measures of consumption expenditure per adult equivalent inequality were very high at the bottom of the distribution ge (0), with a score of 0.6734 followed by medium ranges of expenditures ge (1) of 0.4138 and expenditures in the upper part of the distribution ge (2) of .3803 (table 6). this implies that expenditure inequality was very high for the bottom poor household groups and gains little from urban-induced expansion. zelalem et al. consumption inequality incidence of peri-urban farm households 195 table 6. summary of overall inequality indices. inequality measures estimates expenditure deciles first(poorest) 12394.97 etb tenth(richest) 14310.81 etb deciles dispersion ratio 1.155 gini coefficient gc 0.4858 general entropy ge(0) 0.6734 ge(1) 0.4138 ge(2) 0.3803 3.5. expenditure inequality decomposition by displacement status the results revealed that inequality decomposition among displaced and non-displaced farm households. the highest gini coefficient is registered in displaced farm households (0.3959), followed by non-displaced farm households (0.2204) (table 7). this indicates that expenditure inequality difference was significantly high among displaced and non-displaced farm households since urban expansion results in reducing the displaced farm households' income as well as private asset holdings such as land and livestock holdings. moreover, total inequality was decomposed into between and within periurban farm household groups. the result in table7 provides that, between-group inequality component only explains a large share of total inequality as compared to within group. hence, the values of the gini coefficient within and between groups were 0.1295 and 0.3576, respectively. on the other hand, the result of general entropy (ge) inequality decomposition was high for displaced farm household heads at the bottom of expenditure distribution (0.3011). the level of consumption expenditure also showed almost similar values at ge (1) and ge (2) expenditures distribution (table7). on the other hand, the highest inequality registered was in the between group as compared to within the group. the entropy index result of the between group is high at the bottom of expenditure distribution (0.4944), followed by medium expenditure distribution (0.3230). by contrast, real expenditure inequality decomposition was low as well as no change for non-displaced farm households at the bottom, medium, and top ranges of expenditure with values of 0.0886, 0.0787, and 0.0783 respectively. this implies that urban induced expansion in the peri-urban area results in widening consumption expenditure gaps of displaced farm households as compared to their counterfactuals (non-displaced) farm households since they were dispossessed from their farmland as well as properties. table 7. expenditure inequality decomposition displaced and non-displaced group. group gini index population share absolute contribution ge(0) ge(1) ge(2) non-displaced 0.2204 0.5744 0.1178 0.0886 0.0787 0.0783 displaced 0.3959 0.4256 0.0117 0.3011 0.2524 0.2549 within-group 0.1295 0.1790 0.0907 0.1209 between-group 0.3576 0.4944 0.3230 0.2612 population 0.4858 0.4858 0.6734 0.4138 0.3803 the lorenz curve of displaced and non-displaced farm households portrayed that there is a significant disparity of consumption expenditure between the two groups. the lorenz curve depicted below (figure 2) indicates that the consumption expenditure of displaced farm households lies far below the perfect equality line relative to non-displaced farm households. this implies that urban induced displacement results to depletion of useful assets such as livestock holding and farmland, which as a result reduces farm households’ income. this ultimately widens consumption expenditure inequality among the displaced and non-displaced farm households. zelalem et al. east african journal of sciences volume 16(2): 187-198 196 figure 2. lorenz curve of displaced and non-displaced farm households. 4. conclusions and policy implications deciles ratio, gini coefficient and generalized entropy inequality indices were employed to examine the inequality in consumption expenditures prevailing among displaced and non-displaced farm households. the result of deciles distribution has demonstrated that a large segment of the displaced farm households’ appeared to be concentrated in the poorest deciles while the nondisplaced farm households were concentrated in the top or richest deciles. similarly, the gini coefficient result revealed that the consumption expenditure inequality in the displaced farm households exceeded the nondisplaced farm households. correspondingly, the outcome of general entropy (ge) inequality decomposition depicted that urban expansion brought a dramatic increase in inequality of consumption expenditure for displaced farm households at all ranges of expenditure distribution relative to non-displaced farm households. thus, the overall result of the inequality indices manifested that horizontal expansion of cities towards preexisting rural villages resulted in displaced farm households gaining little from rising urbanization as a result caused high gap in consumption expenditure among displaced and non-displaced farm households. therefore, the government and other stakeholders should reconsider the land policy in relation with rural land and urban expansion. to address problems pertaining to urban expansion and consumption inequality of displaced farm households, the government should secure the farmers the right to own land so that they can negotiate and sell their land at market prices as they do for their other assets. in addition, the government should avoid the nominal compensation and have a policy of sufficiently compensating evicted farmers from their land because of urban expansion. the compensation should be comparable with current value of urban land and the government should monitor the genuine implementation of compensation. moreover, towns’ administrations should devise methods in the short run to subsidize displaced farm households on food and basic non-food items that could help them lower their living costs and reduce consumption inequality until they fully rehabilitate. finally, other interested researchers may focus on intra-households consumption inequality, risk management behavior, regional comparative analysis and psychological impact of urban expansion induced displacement. 5. acknowledgments we extend our gratitude to wollo university, for granting a study leave to the principal researcher for a phd degree from which this paper has emanated. our gratitude also 0 .2 .4 .6 .8 1 l(p) 0 .2 .4 .6 .8 1 percentiles (p) 45° line population non-displaced displaced lorenz curves zelalem et al. consumption inequality incidence of peri-urban farm households 197 goes to university of gondar for covering the research fund. 6. references abubeker mohammed. 2018. land expropriation for cooperative housing in amhara region, ethiopia. process and impacts on the peri-urban farming communities. 9–12 may, 2018conference paper, fig congress. achamyeleh gashu. 2014. peri-urban land rights in the era of urbanization in ethiopia: a property rights approach. african review of economics and finance, 6(1): 120–138. addisu mera. 2015. effects of urban sprawl on the livelihood of suburban agricultural community: the case of sara ampol, yeka tafo and chorizo area, yeka sub city, addis ababa. phd dissertation, addis ababa university, ethiopia. pp.147. addisyihun abayneh. 2019. housing and settlement transformations in the surrounding peri-urban areas of hosanna town: the cases of ambicho and kidigisa, hadiya zone, ethiopia. msc. thesis, ethiopian institute of architecture, building 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ababa, ethiopia. world bank. 2005. introduction to poverty analysis. poverty manual. world bank institute, august 2005. world bank. 2014. harnessing urbanization to end poverty and boost prosperity in africa. world bank, washington, dc. world bank. 2015. ethiopia urbanization review: urban institutions for a middle-income ethiopia. world bank, washington, dc. https://openknowledge.worldbank.org/handle/10986/15842 https://openknowledge.worldbank.org/handle/10986/15842 paper ii: effect of non conventional egg storage methods on the external and internal egg qualities east african journal of sciences (2018) volume 12 (2) 137-144 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: mohamedkrt7@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) effect of non-conventional storage methods on external and internal egg qualities mohammed y. kurtu 1*, dereje duressa¹, and alemu yami ² 1 haramaya university, p. o. box 138 dire dawa, ethiopia ² us aid addis ababa, ethiopia abstract: to know and identify the traditional practices and generate relevant information on egg storage methods, a survey work was conducted in the east wollega zone of ethiopia. the survey was carried out with a stratified sampling technique and a structured questionnaire using a total of 315 households (225 from rural and 90 from urban owning chickens) were purposefully selected. two experiments, of similar experimental materials, procedures and designs were conducted at different time of the year (may and august) to evaluate these traditional storage methods at haramaya university poultry farm. a factorial experiment of 2 by 5 with completely randomized design using storage containers and storage time as treatment was used. the storage times were 4, 6, 8, 12 and 20 days. five most common egg storage containers were identified in the rural and urban areas of east wollega. these storage methods include cartons, polyethen bags, baskets, clay pots and teff grain. the result further indicated that depending on the availability of the storage materials in the locality, 87 percent of the urban households (n = 90) store eggs in cartons and polyethene bags in order of availability. seventy nine percent of the rural households (n = 225) ranked teff as the most common storage materials used followed by the basket and clay pots. among the quality parameters considered, weight loss (%) and daily weight loss (%) of eggs were highly affected (p < 0.001) by storage containers, durations and their interactions during both experiments. the maximum weight loss was observed after storage period of 16 days for all containers. polythene bags storage maintained minimum weight loss vs the baskets at all stages of storage duration. only storage durations had significant effects (p < 0.05) on the egg shell thickness during experiment i. inconsistent but significant effect of storage durations was observed on the shell weight during experiment i, and weights of yolk and albumen during experiment ii. storage containers during experiment i, and storage durations during experiment ii showed significant effects on albumen height and haugh unit values. except polythene bags which had higher albumen height and haugh unit values, the other containers did not show significant variations for both parameters. the effect of storage duration on these parameters was linear with increasing storage duration; and higher beyond the 16 days of storage. thus, it was concluded that using polyethylene bags and 16 days of storage could give the best result to store eggs among the traditional methods compared in this experiment. keywords: traditional egg storage; changes in egg quality; optimum egg storage duration 1. introduction the majority of poultry in ethiopia are raised under traditional system of production. these birds contribute eggs for hatching and consumption (market). alemu (1995) stated that collecting agents gather together larger numbers of eggs stored in various methods before marking them. the marketing places are usually larger towns and cities where distances to these marketing points are long hence, there is marked deterioration of egg quality. this may create problems on quality and hatchability of eggs from the traditional system of production. thus, eggs decline in quality and hatchability very easily from the time of laying the different storage methods coupled with storage time practiced by farmers can aggravate the loss in egg quality. the quality deteriorations are mainly associated to the external and internal quality of eggs (romanoff and romanoff, 1949; stadelman and cotterril, 1977; mountney, 1989). consequently a lot of eggs could be lost and hatchability would dramatically affected. little work has been done in this regard especially under ethiopian condition, hence there is a knowledge gap in understanding the traditional egg storage methods used in ethiopia particularly in wollega zone despite the prevailing of various traditional methods being used by farmers. this study is, therefore, designed to investigate and assess the effect of different storage methods on internal and external qualities of eggs. 2. materials and methods 2.1. study design a formal survey with stratified sampling technique was applied for survey data collection. five pas and two towns were randomly selected from each of the agroecologies. then, 15 households who currently own poultry were randomly selected from each of the selected peasant associations and towns and subjected to mohammed et al. east african journal of sciences volume 12 (2) 137-144 138 the structured questionnaires. a total of 315 households (225 from rural and 90 from urban) were included in the survey. information on egg storage practices were collected and described using descriptive statistics. two experiments of similar materials and procedures were conducted as factorial experiment 2 by 5 in a completely randomized design using different storage containers and storage time as treatment. the storage containers were bamboo basket, cartons, clay pots, polythene bags and mixing with teff grains and the storage times used were 4, 6, 8, 12 and 20 days. the experiments were conducted at different times of the year (may and august) at haramya university (hu) poultry farm in year 2000. all eggs used in the experiment were obtained from white leghorn layers having equal age, in similar laying stage and kept under the same standard management of the hu poultry farm. eggs were collected twice per day (following the usual procedure of the farm) at 11: am and 5: pm using plastic trays. eggs from four consecutive collections were used for each of the storage durations. storage periods were calculated from the time the eggs were allocated to the storage containers. after collection, eggs were candled and eggs with visible cracks were removed. eggs were then weighed using a sensitive balance and their initial weights were recorded and marked on the blunt end of each egg. codes referring to the storage container and duration were randomly given and marked on each egg. at the end of each collection period, all eggs were allocated to the respective containers at random. except the polythene bags whose open side were folded once, the containers were not covered during the storage period. the temperature of the room was recorded four times daily during the entire period of the storage using a thermo-hygrometer. 2.2. measurements all eggs stored in each container (bamboo baskets, cartons, clay pots polyethylene bags, and teff grains) and for each specific storage period i.e. 2, 6, 8, 12 and 20 days (treatments) were taken out for measurement. the parameters used to measure the effect of storage methods on internal and external egg quality were according to haugh (1937); egg weight loss percentage weight loss daily weight loss of eggs (%) eggshell thickness albumen height (ah) haugh unit (hu) 2.3. data analysis data analysis of the experiment was performed using the computer software (mstat, 1989). whenever the anova revealed significant differences among the treatment means, duncan’s multiple range test (dmrt) was used to separate the means. all statements of significance are based on the 5 % level of probability. 3. results and discussion five most common egg storage containers were identified in the rural and urban areas of east wollega (table 1). these storage methods include cartons, polyethen bags, baskets, clay pots and teff grain. the result further indicated that depending on the availability of the storage materials in the locality, 87 percent of the urban households (n = 90) store eggs in cartons and polyethene bags in order of availability. seventy nine percent of the rural households (n = 225) ranked teff as the most common storage materials used followed by the basket and clay pots. a similar results has been obtained from the previous work done by tadele (1990). table 1. some most common egg storage containers identified by the surveyed urban and rural households of east wollega (number and percent). container rank urban rural no. % no % 1 5 5.6 74 32.9 2 14 15.6 94 41.8 baskets 3 20 22.2 66 29.3 4 33 36.7 54 24 5 39 43.3 60 26.7 1 5 5.6 43 19.1 2 10 11.1 52 23.1 clay pots 3 15 16.7 77 34.2 4 17 18.9 50 22.2 5 21 23.3 57 25.3 1 3 3.3 108 48 2 11 12.2 70 31.1 mixing with teff grain 3 12 13.3 64 20.4 4 18 20.0 40 17.8 5 13 14.4 40 17.8 1 42 46.7 2 32 35.6 9 4 cartons 3 23 25.6 21 9.3 4 11 12.2 45 20 5 10 11.1 44 19.6 1 37 41.1 2 23 25.6 polythene 3 20 22.2 15 6.7 4 11 12.2 36 16 5 7 7.8 24 10.7 storage containers, durations and their interactions had highly significant effects (p < 0.001) on the percent weight loss of eggs during both experiments. the mean percent loss of egg weights due to the interaction effects of storage containers and durations during experiments i and ii are shown in tables 1 and 2, respectively. in experiment one, the mean percent weight loss of eggs during the first 4 days of storage was not significant for all containers. but eggs stored in all containers lost about 1 percent of their original weights during the first 4 days of holding in both experiments. in both experiments, the rate of weight loss was increasing when the storage duration was extended mohammed et al effect of non-conventional egg storage methods on egg qualities 139 beyond 16 days (tables 1 and 2) with the exception of polyethylene which was lowest 2.2 and 0.03 for experiment 1 and 2 respectively. as indicated in table 3, for experiment i, the percent loss of weight from eggs kept in all containers except polythene bag increased linearly; the rate of increment being highest beyond the 16th day of holding for all containers. similar trend was also observed during experiment ii (table 4). at the end of the 20 days of storage, the maximum weight loss was recorded from eggs kept in basket, carton, clay pot and mixing with teff grain during both experiments. during experiment i, the mean weight loss from eggs kept in these containers was more than 5 percent during the longest (20 days) storage. table 2. total weight loss (percent) of eggs stored using different containers each at different length of storage period (experiment i). storage durations (days) containers 4 8 12 16 20 control 0.78q 1.49n 1.90lm 2.26j 4.73d baskets 1.2o 2.03kl 2.64hi 3.78e 6.30a cartons 1.07op 1.98kl 2.48i 3.60e 5.76b clay pots 0.88pq 0.75q 1.75m 2.80gh 5.57c polythene 0.88pq 0.36r 0.35r 0.50r 2.16jk mixing with teff grain 1.02op 2.89g 2.50i 3.28f 5.50c containers x durations interaction *** note: *means followed by the same letters within rows and columns are not significantly different; *** = significant at 0.1% level of probability; dmrt. table 3. total weight loss (percent) of eggs stored using different containers each at different length of storage period (experiment ii). storage durations (days) containers 4 8 12 16 20 control 1.31k 1.36jk 1.58ij 1.61ij 2.61d baskets 1.28k 1.68hi 2.01fg 2.37de 3.48a cartons 1.21k 1.67hi 1.83jhi 1.90gh 2.95c clay pots 1.14k 1.66hi 1.80ghi 1.6ij 2.51d polythene 0.64l 0.48lm 0.42lm 0.25m 0.34m mixing with teff grain 1.26k 1.71hi 2.18ef 2.44d 3.23b containers x durations interaction ** note: means followed by the same letters within rows and columns are not significantly different, ** = significant at 1% level of probability, dmrt. table 4. average daily weight loss (percent) of eggs stored using different containers each at different length of storage period (experiment i). storage durations (days) containers 4 8 12 16 20 control 0.20hijk 0.19ijkl 0.16kl 0.14lm 0.24efgh baskets 0.30bc 0.25cdefg 0.22fghij 0.24efgh 0.32b cartons 0.27bcdef 0.25def 0.21ghij 0.22fghi 0.29bcd clay pots 0.22fghij 0.09n 0.15lm 0.18ijkl 0.28bcde polythene 0.22fghij 0.04o 0.03o 0.03o 0.11mn mixing with teff grain 0.25cdefg 0.36a 0.21ghij 0.20ghjk 0.27bcde containers x durations interaction *** s.e.m. () = 0.015; c.v. (%) = 10.19 note: means followed by the same letters within rows and columns are not significantly different; ***= significant at 0.1% level of probability; s.e.m. = standard error of the mean; cv = coefficient of variation. mohammed et al. east african journal of sciences volume 12 (2) 137-144 140 table 5. average daily weight loss (percent) of eggs stored using different containers each at different length of storage period (experiment ii) storage durations (days) containers 4 8 12 16 20 control 0.33a 0.17efg 0.13hij 0.10k 0.13hij baskets 0.32ab 0.21d 0.17efg 0.15ghi 0.17ef cartons 0.30bc 0.21d 0.15fgh 0.12jk 0.15ghi clay pots 0.28c 0.21d 0.15gh 0.10k 0.13ij polythene 0.16efg 0.06l 0.03m 0.02m 0.02m mixing with teff grain 0.31ab 0.21d 0.18e 0.15fgh 0.16efg containers x durations interaction *** s.e.m. () =0.015; cv.(%) =10.19 note: means followed by the same letters within rows and columns are not significantly different; *** = significant at 0.1% level of probability; s.e.m. = standard error of the mean; cv = coefficient of variation. in both experiments, eggs stored in polythene bags were recorded the lowest weight loss for all storage durations. accordingly, eggs stored in polythene bags lost only 2 and 0.34 percent of their initial weights at the end of 20 days during the first and second experiments, respectively. the low weight loss of eggs kept in polythene bags may be attributed to the ability of the material to prevent moisture loss from eggs by lowering the direct air blowing around the eggs. this is in agreement with the findings of several authors such as romanoff and romanoff (1949) and smith (1930) who recommended the enclosure of eggs in plastic containers during storage for an extended period. conversely, eggs stored in bamboo baskets with straw bedding lost the highest weight for all storage periods which could be due to the nature of the basket that allows free movement of air around the eggs. smith (1930) and. romanoff (1940) concluded that the rate at which the egg looses weight by evaporation tends to be greater if the air surrounding the egg is moving rapidly. the temperature of the basket was similar to that of the room. the effects of storage containers x duration interaction on the mean percent egg weight losses per day during the entire period of experiment i and ii are presented in tables 3 and 4, respectively. similar pattern as the total egg weight loss was observed for the daily percent weight loss of eggs. though the figures are inconsistent for experiment i, the daily percent weight loss of eggs kept in all containers showed a linearly declining trend up to the 16th day of storage during both experiments. in agreement with this point, romanoff (1940, 1943b) concluded that in terms of the egg’s original weight, the daily loss diminishes through out the holding periods. however, in both experiments of the present study the daily percent weight loss of eggs kept in all containers showed a marked increase during the last 17 to 20 days of holding. table 6. effects of storage containers on some external and internal qualities of eggs during experiment i. containers wl (%) wlpd (%) sht(mm) shw (%) ykw (%) albw (%) ah(mm) hu control 2.33d 0.18b 0.339 9.9 31.7 58.6 4.3b 76b baskets 3.19a 0.27a 0.326 9.7 31.1 59.2 4.0b 74b cartons 2.98b 0.25a 0.322 9.7 31.9 58.4 4.4b 76b clay pots 2.35c 0.18b 0.331 9.6 31.5 58.9 4.3b 76b polythene 0.85e 0.09c 0.331 10.2 31.1 58.8 5.6a 86a mixing with teff grain 3.04b 0.26a 0.334 10.2 31.2 58.6 4.3b 77b prob.  *** *** ns ns ns ns ** * s.e.m. () 0.028 0.007 0.002 0.027 0.03 0.026 0.008 1.815 c.v. (%) 3.68 10.19 4.83 2.75 1.72 1.08 15.72 6.22 note: means within columns followed by common letters are not significantly different from each other; wl = percentage weight loss; wlpd = percentage weight loss per day; shw = percentage weights of shell; ykw = yolk weight; albw = albumen weight; sht = shell thickness; ah = albumen height and hu = haugh unit; * = significant at 5%; ** = significant at 1%; *** = significant at 0.1%; ns = not significant at 5%; s.e.m. = standard error of the mean; cv = coefficient of variation. mohammed et al effect of non-conventional egg storage methods on egg qualities 141 table 7. effects of storage durations on some external and internal qualities of eggs during experiment i. storage duration (days) s.e.m parameter 4 8 12 16 20 significance () wl (%) 0.97e 1.58d 1.94c 2.70b 5.00a *** 0.026 wlpd (%) 0.24a 0.20b 0.16c 0.17c 0.25a *** 0.006 sht (mm) 0.322b 0.336ab 0.321b 0.342a 0.332ab * 0.002 shw (%) 9.6b 9.8ab 9.6b 10.2a 10.0ab * 0.025 ykw (%) 30.8 31.7 31.6 31.4 31.5 ns 0.028 albw (%) 59.6 58.5 58.9 58.3 58.3 ns 0.024 ah (mm) 5.5a 4.6b 4.8ab 3.9c 3.5c *** 0.007 hu 84a 79a 80a 73b 70b *** 1.657 note: means within rows followed by common letters are not significantly different from each other; wl = percentage weight loss; wlpd = percentage weight loss per day; shw = percentage weights of shell; ykw = yolk weight; albw = albumen weight; sht = shell thickness; ah = albumen height and hu = haugh unit; *= significant at 5%; **= significant at 1%; ***= significant at 0.1%; ns = not significant at 5%; s.e.m. = standard error of the mean. during the first experiment, eggs stored in polythene bags and clay pots lost small weights per day when storage period was extended from 8 to 16 days. after 20 days of storage (experiment i), the daily weight loss (%) of eggs from all containers except the polythene bag did not show significant variation. the mean daily weight losses of eggs kept in the polythene bag were 0.22, 0.04, 0.03, 0.03, and 0.11 percent during storage periods of 4, 8, 12, 16, and 20 days respectively. except for the first 4 days of holding, the mean percent weight loss of eggs kept in polythene bags was significantly lower than eggs kept in cold room. during experiment ii, on the other hand, the daily weight loss of eggs from polythene bags were significantly lower than the control for all storage periods. in experiment i, the daily percent weight loss of eggs stored in all containers at the end of 20 days was slightly higher than the corresponding values observed at 4 days of storage, where as the reverse was true during the second experiment. the relatively high environmental temperature that prevailed during the entire period of the first experiment might be one of the main reasons for the high weight losses of eggs during the first experiment than the second. it has been indicated by many investigators that temperature and relative humidity are the most important environmental variables to affect the loss of moisture from eggs during holding; other factors being kept constant. romanoff (1940) stated that the rate of weight loss is accelerated at higher temperatures and retarded at higher relative humidity. egg shell thickness only the storage durations had significant effects on shell thickness (p < 0.05) during the first experiment (table 8). statistically, no significant differences were observed (p > 0.05) among the means of egg shell thickness for storage containers (table 7), durations (table 8), and their interactions during experiment ii. table 8. effects of storage containers on some external and internal qualities of eggs experiment ii. containers wl (%) wlpd (%) sht(mm) shw (%) ykw (%) albw (%) ah(mm) hu control 1.70c 0.17c 0.341 9.0 31.5 59.5 5.6 88 baskets 2.16a 0.20a 0.351 9.3 31.6 59.1 5.7 90 cartons 1.91b 0.19b 0.336 9.1 32.2 58.7 5.4 86 clay pots 1.74c 0.17c 0.328 8.7 32.1 59.2 5.1 86 polythene 0.43d 0.06d 0.332 9.3 31.1 59.5 5.6 87 mwtg¶ 2.16a 0.20a 0.343 9.3 32.5 58.7 5.0 84 significance *** *** ns ns ns ns ns ns s.e.m. () 0.038 0.003 0.006 0.196 0.304 0.358 0.024 1.648 cv (%) 7.22 6.14 5.41 6.81 3.03 1.92 14 6.02 note: mwtg¶ = mixing with teff grain; means within columns followed by common letters are not significantly different from each other; wl = percentage weight loss; wlpd = percentage weight loss per day; shw = percentage weights of shell; ykw = yolk weight; albw = albumen weight; sht = shell thickness; ah = albumen height and hu = haugh unit; *** = significant at 0.1%; ns = not significant at 5%; s.e.m. = standard error of the mean; cv= coefficient of variation. mohammed et al. east african journal of sciences volume 12 (2) 137-144 142 table 9. effects of storage durations on some external and internal qualities of eggs during experiment ii. storage duration (days) s.e.m parameter 4 8 12 16 20 significance () wl (%) 1.14d 1.43c 1.64a 1.70b 2.52a *** 0.035 wlpd (%) 0.28a 0.18b 0.14c 0.11e 0.13d *** 0.003 sht (mm) 0.331 0.347 0.341 0.337 0.337 ns 0.005 shw (%) 9.1 9.4 9.0 9.2 9.0 ns 0.179 ykw (%) 31.0c 32.3a 31.9ab 31.4bc 32.2ab * 0.278 albw (%) 59.9a 58.3c 59.2abc 59.4ab 58.8bc * 0.327 ah (mm) 6.5a 5.5b 5.4b 4.9bc 4.6c *** 0.022 hu 94a 87b 88b 83bc 81c *** 1.504 note: means within rows followed by common letters are not significantly different from each other; wl = percentage weight loss; wlpd = percentage weight loss per day; shw = percentage weights of shell; ykw = yolk weight; albw = albumen weight; sht = shell thickness; ah = albumen height and hu = haugh unit; * = significant at 5%; ** = significant at 1%; *** = significant at 0.1%; ns = not significant at 5%; s.e.m. = standard error of the mean; cv = coefficient of variation. percentage weights of the major egg parts there were no significant effects of type of storage containers and container x duration interaction observed (p > 0.05) on the mean percentages of the shell, yolk and albumen during both experiments (table 7). storage durations had significant effects on the weight of egg shell (p < 0.05) during experiment i (table 8). as indicated in table 10 during experiment ii, the percent weights of yolk and albumen were significantly affected (p < 0.05) by storage duration. though the trend seems inconsistent with days of holding, the percent weights (proportion) of yolk and albumen fluctuates with a negatively correlated manner. the significant weight loss of albumen was observed at day 8 of holding during which the yolk gained the maximum weight. the inconsistency of the proportion of the two components might be due to the fluctuating environmental temperature during the entire period of the experiment. it has been indicated that during the early holding period, the albumen looses water not only by evaporation through the shell, but also by diffusion to the yolk. this movement of water between the components is the result of osmotic gradient across the vitelline membrane. romanoff (1949) reported that the direction of diffusion is initially from albumen to yolk, because the osmotic pressure of the yolk is greater. the movement of water reverses when albumen, becomes more concentrated as a result of diffusion. smith (1990) also reported that the noticeable enlargement of the yolk in the aging egg is due to its increased content of water. albumen height (ah) and haugh units (hu) both albumen height and haugh unit values were significantly affected by storage containers during experiment i, (table 7) whereas the effect was non significant for both parameters during experiment ii (table 8). the interaction of storage containers and durations had no significant effects (p > 0.05) on the albumen height and hu values (table 3) for both experiments. except the polythene bag that had significantly higher ah and hu values (5.6 and 86 respectively), the other containers did not show significant difference for the mean values of both parameters. the highest albumen height observed for eggs stored in polythene bags might be attributed to the ability of the plastic material to minimize the rate of water loss mainly from the albumen. north (1984) indicated that water comprises about 84 percent of the albumen and whenever the rate of water loss is minimum the albumen retains its water content and the dense part will remain firm giving higher ah and hu values which is an indication of internal quality. during experiment ii, (table 7) the mean hu values were in descending order and the variation was not statistically significant (p > 0.05). storage durations had highly significant effects (p < 0.001) on the albumen height and hu values during both experiments (tables 7 and table 8). during experiment i, the mean ah values were moreover, higher rates of ah and hu losses observed from eggs held beyond 12 days. during experiment ii the loss of albumen height (ah) and haugh unit (hu) values were linear with extended storage periods compared to experiment i (table 7 and 8). the relatively lower environmental temperature and higher initial egg weights during the second experiment might be the reasons for the higher albumen height (ah) and hough unit (hu) values observed in experiment ii (table 9) than the first. mountney (1989) indicated that as the environmental temperature increases, the carbonic acid held in the albumen breaks yielding additional carbon dioxide and water which will escape to the environment through the eggshell. as a result the much in fibers lose their firmness and the proportion of the thick albumen decreases. 4. conclusion in both experiments, eggs stored in polythene bags were found to have the lowest weight loss for all storage durations. the low weight loss may be attributed to the mohammed et al effect of non-conventional egg storage methods on egg qualities 143 ability of the material to prevent moisture loss from eggs by lowering the direct air blowing around the eggs. conversely, eggs stored in bamboo baskets with straw bedding lost the highest weight for all storage periods which could be due to the nature of the basket that allows free movement of air around the eggs. except the polythene bag that had significantly higher ah and hu values (5.6 and 86 respectively), the other containers did not show significant difference for the mean values of both parameters. the highest albumen height observed for eggs stored in polythene bags might be attributed to the ability of the plastic material to minimize the rate of water loss mainly from the albumen. the overall result of the present study show that egg kept for a period of more than 16 days could be stored in a polythene bag to maintain its quality. moreover, egg should not be held for longer periods especially in hot season during which the environmental temperature is high. 5. acknowledgement the authors fully appreciate haramaya university for providing the main author with both material and financial support to undertake this work. all staff in the department of animal sciences that have directly or indirectly made an important contribution to the success of this work are highly acknowledged. 6. references alemu, y. 1995. poultry production in ethiopia. world’s poultry science journal, 51: 197-201. haugh, r. r. 1937. the haugh unit for measuring eggs quality. us. poultry magazine mountney, g. j. 1989. poultry products technology (2nd edn.). food products press, new york, london mstatc. 1989. a micro-computer statistical program for experimental design, data management and data analysis. michigan state university, crop and soil sciences, agricultural economics and institution of international agriculture, usa. north, m. o. 1984. commercial chicken production manual (3rd. edn.). avi publishing co; westport, conn. romanoff, a. l. and romanoff, a. j. 1949. the avian egg. the macmillan company new york, wiley. romanoff, a. l. 1940. physico chemical changes in unfertilized, incubated eggs of gallus domestic us. f o res., 5: 291 306 romanoff, a. l. 1943b. distribution of dry constituents and of yolk and albumin in the developing avian egg. a note rec. 87: 303-306 smith, a. j. 1930. department of animal science. ind .research (brit), food investigation. department, 1929. 74-80. smith, a. j. 1990. poultry-tropical agriculturalist series. cta, macmillan publishers, london, pp 179-189. stadelman, w. j. and cotterill, o. j. 1977. egg science and technology (2nd edn.). university of missouricolombia. tadelle, d. 1996. studies on village poultry production systems in the central high lands of ethiopia. msc. thesis. swedish university of agricultural sciences, uppsala, sweden. mohammed et al. east african journal of sciences volume 12 (2) 137-144 144 east african journal of sciences (2019) volume 13 (1) 1-6 ______________________________________________________________ n blicensed under a creative commons *corresponding author. e-mail: omotade29@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) efficiency of intercropping system under smallholder farmers in osun state, nigeria babatunde, r. o., omoniwa, a. e.* and oluyemi, o.d. 1department of agricultural economics and farm management, university of ilorin, ilorin, nigeria abstract: recently, the constant rise in population growth has resulted in increased pressure on available agricultural land. this has given rise to greater land use intensification and crop diversification by smallholder farmers. however, information is scarce about the economic efficiency of the system in the osun state. the study was carried out to assess the technical and allocative efficiencies of intercropping systems in osun state of nigeria. a three-stage random sampling technique was used to select a total of 120 smallholder farmers across six local communities namely owode, ologede, ifewara, iperindo, ilerin and odundun from which responses were solicited with the aid of a questionnaire. the descriptive and stochastic production frontier was used to analyze the data gotten from the smallholders. the results showed that the average technical efficiency index was 67%, while allocative efficiency was 13%. the factors that significantly influenced the production were farm size, quantity of fertilizer used as well as the cost of other inputs. while those that significantly influence the technical and allocative efficiencies of intercropping systems in the study area were the educational status, household size in adult equivalent and membership to cooperatives. it is, therefore, recommended that farmers require training on the appropriate skills required to operate an efficient intercropping system. this can be done through the cooperative societies. this will help the farmers in the efficient allocation of resources available to them. keywords: allocative; efficiency; intercropping; land and technical 1 introduction one of the current challenges in agriculture is to place crop production systems on a sustainable platform. this demands operating of the systems at high productivity and economic levels even in the face of the negative impact of climate change on agricultural productivity. sustainable crop production and management lies within land intensification (fao, 2011; kassam and friedrich, 2012). crop diversification such as intercropping has a potential to improve yield. moreover, the global food system problems as impacted by climate change, population growth, rapid urbanization, and pressure on land calls for these adaptive approaches to food security (godfray et. al., 2010). traditionally, multiple cropping systems such as intercropping have been estimated to provide as much as 15 to 20 percent of the world’s food supply (koohafkan and altieri, 2016). intercropping is the agricultural practice of cultivating two or more crops in the same space at the same time. it is a commonly used cropping practice that aims to match efficiently crop demands to the available growth resources and labor. the most common advantage of intercropping is the production of greater yield on a given piece of land (dordas and damalas, 2011). intercropping also improves soil fertility and increases soil conservation through greater ground cover than sole cropping (fukai and trenbath, 1993; russell, 2002; hauggard-nielson et al, 2001). intercropping is also efficient for the conservation of biodiversity by providing habitat for a variety of insects and soil organisms that would not be present in a single-crop environment. this in turn can help to limit the outbreaks of crop pests (jane, 2006). in nigeria, intercropping is a common cropping system practiced by almost all small-scale farmers. this is because it is cheaper while playing a significant role in integrated pest management (sanni et al., 2011). one of the major problems limiting crop production is weed infestation. weed control is a serious problem for most of the smallholders, particularly in the absence of adequate technologies as well as in the light of the emergence of weeds resistant to herbicides and the concerns about herbicide residues in food, soil, and groundwateratmosphere (abouziena and haggag, 2016). therefore, weeds limit the production potentials of resource poor farmers and thereby affect the wellbeing of these smallholders (llewellyn et al, 2016). also, the increasing menace of erosion in recent times has imposed a serious constraint on land availability. the consequence of which are low productivity, increasing soil degradation and agricultural land fragmentation as well as land use intensification which is capable of affecting their level of efficiency in crop productivity (kumer and pani, 2015). according to dordas and damalas (2011), global population is projected to rise from the current seven billion to nine billion in few decades. therefore, almost three quarters increase in land productivity will be needed to meet the future growth in global food demand by 2030, either from yield increases or increases in cropping intensity (brij and anil, 2013). it is, therefore, safe to emphasize sustainable crop production through babatunde et al. east african journal of sciences volume 13 (1) 1-6 2 efficient land intensification as an innovative strategy capable of feeding the projected nine billion people (dordas and damalas, 2011). although intercropping is an accepted agricultural practice to increase the productivity of scarce land resources, the levels of the efficiency may differ depending on the knowledge and experiences of farmers in practicing it properly. intercropping is practiced by most smallholders in nigeria in divers forms (agbongiahuoyi et al., 2012). however, information is scarce about the economic efficiency of intercropping systems in the osun state, nigeria. therefore, it is necessary to generate information from systematic studies in the state to assess as well as improve the economic efficiency of these intercropping systems. thus, this research was conducted with the objectives of examining the technical and allocative efficiencies of intercropping systems and also to identify the factors influencing them in osun state, nigeria. the intercropping systems commonly practiced in osun state are maize/cassava, maize/cassava/yam, cocoa/kolanut and cocoa/kolanut /palm tree. 2 methodology 2.1 study area the study area is osun state located in the south-west geopolitical zone of nigeria. osun state is an inland state with its capital in osogbo city and lies on latitude of 8010' n and longitude of 605's on the south. the modern osun state was created in 1991 from part of the old oyo state and it is divided into three (3) main agricultural zones namely iwo, osogbo and ife/ijesha (osun adp, 2012). the major types of crops grown in the state are maize, cocoa, plantain, cassava, and the likes. 2.2. sampling technique and data collection the data was collected through the use of a structured questionnaire from 120 smallholders. a three-stage random sampling technique was employed. the first stage was the random selection of one (1) agricultural zone from the three (3) zones in the state. the second stage was the selection of six (6) communities from the selected agricultural zone and the last stage was the random selection of twenty (20) farmers from each of the selected communities to make a total of 120 smallholders. data were collected that could help understand the socioeconomic structure of the smallholders. these include the age (years), farming experience (years), household size, farm income (naira), grain equivalent of output (kg), and farm size (hectares), among others. data were also collected that were used as the inefficiency predictors; access to credit facilities, membership of cooperative societies, gender and educational level. 2.3 tools of analysis descriptive statistics was used to assess the socioeconomic characteristics of farmers. the stochastic frontier was used to examine the technical and allocative efficiencies of intercropping systems and also the factors influencing the technical and allocative efficiencies of intercropping systems in the study area. the stochastic production function is defined as: where yi is the grain equivalent of the outputs of farmer i, xi‘s are the input variables, ai are production coefficients and vi is a symmetric error term associated with random factors not under the control of the farmers and assumed to be independently and identically distributed (i.i.d.) with a random error that is independent of ui. ui is the non-negative efficiency measured relative to the stochastic frontier, which is also assumed to be i.i.d. distributed as half normal (at zero mean) or truncated half-normal (at mean μ), or with two-parameter gamma distributions. the farm-specific technical efficiency is defined in terms of observed output (yi) to the corresponding frontier output (yi*) using the available technology derived from the result of the equation i above as: te takes value on the interval (0, 1). the stochastic frontier cost functions model for estimating farm level overall economic efficiency is specified as: where; ci represents total production cost, yi represents grain equivalent of the output produced, pi represents cost of input, α represents parameters of cost function and εi represents the error term. however, because inefficiencies are assumed to always increase costs, error components are preceded by positive signs (igbal et al., 2007). the farm specific economic efficiency (ee) was defined as the ratio of minimum observed total production cost (c*) to actual total production cost (c). … ..(iv) ee took the value between 0 and 1. hence a measure of farm specific allocative efficiency (ae) was thus obtained from technical and economic efficiencies estimated as: . (v) the range was from 0 to 1. babatunde et al. efficiency of intercropping system in nigeria 3 for this paper, y = grain equivalent of output (kg) where: x1 = farm size (hectares) x2 = family labour (total man-days) x3 = hired labour (man-days) x4 = seeds (kg) x5 = pesticides (litres) x6 = fertilizer (kg) the inefficiency predictors: x1 = farming experience (years) x2 = gender (male=1) x3 = age (years) x4 = households size (ae) x5 = members of cooperative societies (yes =1) x6 = access to credit (yes =1) x7 = educational level (formal =1, non-formal =0) 3. results and discussion 3.1 socioeconomic characteristics the summary statistics of the socioeconomics characteristics is shown in table 1. an average farmer in the study area is about 51 years old with a household size of four persons and cultivates a farm size of three hectares. the average farming experience was 23 years and earns an off-farm income of about n21, 180 per month. this implies that most of the respondents in the study area are on the average very agile (that is within their productive years) and thus can still be actively involved in farming. the household size might in turn affect the amount of labour that will be available for farming activities since most smallholders rely on family labour for production activities. these averages are consistent with the reports of nbs (2006) and that of babatunde and qaim (2010). 3.2 factors influencing the technical efficiency of intercropping systems the result of the analysis on the determinants of technical efficiency of intercropping system as shown in table 2 revealed that the farm size had positive coefficient and it was significant at 5%. this indicated that as the farm size increases output also increases. the coefficient of fertilizer was also positive and significant indicating that as the fertilizer usage increases production increases too. for the inefficiency model, the negative coefficient of educational status which was significant at 1% implies that the farmer’s level of technical inefficiency decreases with improved educational status. the negative coefficient for membership of cooperative societies implies that the farmers level of technical efficiency increases with their members. this can be attributed to the fact that educated farmers who are members of cooperative group are likely to be exposed to skill acquisition programs that can enhance their capacities. these relationships are in agreement with several literatures such as those of narala and kala, 2010 and mangu et al, 2015. table 1. socioeconomic characteristics of farmers. variables mean standard deviation age (years) 50.58 10.17 years of schooling 9.38 4.83 household size (adult equivalent) 4.29 1.84 farm size (hectares) 3.32 4.10 farming experience (years) 23.95 12.19 frequency of extension visit (in the last farming season) 2.83 3.64 farm income (n/month) 10, 193 12, 143 off-farm income (n/month) 21, 180 20, 920 table 2. stochastic production function estimates of the factors influencing the technical efficiency of intercropping systems. variables coefficients s.e t-values stochastic frontier constant 9.423 0.493 19.120 farm size (hectares) 0.414** 0.180 2.304 family labour (mandays) -0.907 0.215 -0.423 hired labour (man-days) 0.097 0.180 0.540 seeds (kg) 0.001 0.003 0.169 pesticides (litres) 0.017 0.013 1.300 fertilizers (kg) 0.021** 0.009 2.206 inefficiency model constant 4.293 1.081 3.970 farming experience (years) -0.182 0.186 -0.979 gender (male =1) 0.377 0.418 0.899 age (years) 0.070 0.213 0.416 household size (ae) -0.271 0.652 -0.195 members of cooperatives (yes =1) -0.827* 0.424 1.840 access to credit (yes =1) 0.190 0.430 0.441 educational status -0.586*** 0.126 -4.633 variance parameters sigma-squrared (ᵹ²) 1.413 0.240 5.888 gamma (ɤ) 4.148 0.212 0.195 note: ***, **, and * represent 1%, 5% and 10% level of significance 3.3 factors influencing the allocative efficiency of intercropping system the factors that significantly influence the allocative efficiency of intercropping systems in the study area as indicated in table 3 were the cost of other inputs (this includes the cost of packaging, cost of transporting produce to the farm gate among others) household size, and membership to cooperatives. the estimated coefficient for the cost of other inputs with respect to the allocative efficiency had a positive sign and was significant at the 5%. this implies that cost of other input contributed positively to the allocative efficiency of intercropping systems in the study area. the estimated coefficient for household size and membership of cooperative societies had a negative sign babatunde et al. east african journal of sciences volume 13 (1) 1-6 4 for the allocative inefficiencies, but they were significant at 5%. this implies that as the household size decreases the more allocatively inefficient the production system becomes. this may be as a result of the fact that households with smaller members do not have enough labour to work on the farm and as such resulting in lower reduced output. also, the result shows that nonmembers of cooperative societies are more likely to be inefficient. this may be because they do not possess the skills required to efficiently engage in intercropping systems as some of these ideas and skills are taught within the societies. these results are not too different from that of okoye et al, 2006 who also reported the same relationship. table 3. stochastic production function estimates of the factors influencing the allocative efficiency of intercropping systems. variables coefficients s.e t-values stochastic frontier efficiency model -517810.280 1.000 -517807.63 land rent (n/year) 2.512 2.861 0.878 cost of hire labour (n/man-day) 93.787 5.185 18.083 cost of seeds (n/kg) 7.798 0.553 14.101 cost of fertilizers (n/kg) 33.591 1.903 17.647 cost of pesticide (n/kg) 27.105 2.739 9.894 farming experience (years) -94.070 1.065 88.366 cost of other inputs (n) 15.539** 6.347 2.448 inefficiency model constant -2127.296 1.000 -2127.296 gender (male =1) 5.633 1.000 5.633 age (years) 542.402 1.000 542.402 household size (ae) -1.803** 1.000 -1.803 members of cooperative (yes =1) 46.192** 1.000 -1.083 access to extension services (yes =1) 20.778 1.000 27.778 access to credit (yes =1) 17.032 1.000 170.325 source of land -27.533 1.000 -27.534 educational status -21.739 1.000 -21.729 variance parameters sigma-squrared (ᵹ²) 2260.000 1.000 67282.154 gamma (ɤ) 0.999 1486.2 672851.540 note: ***, **, and * represent 1%, 5% and 10% level of significance 3.3 technical and allocative efficiencies of intercropping systems the frequency distribution of the efficiency estimates obtained from the stochastic frontier model is presented in table 4 and 5 for the technical and allocative efficiencies, respectively. the results in table 4 indicated that technical efficiency indices varied widely with an average efficiency index of 67%. majority (38.3%) of the farmer’s falls into the modal class (60-70%) while the lowest class (50-60%) was just about 3.3%. this could be because the farmers had relatively bigger farm. they are more experienced with the skills to efficiently engage in intercropping systems. none of the respondent achieved a technical efficiency of 100% which implies that there is still more room for improved efficiency of intercropping system in the study area. this result is not too different from those of altieri (1999) for national directorate of employment (nde) farmers in ondo state (bifarin et al., 2010). table 4. technical efficiencies of intercropping systems. technical efficiency index frequency % 0.501 -0 .600 4 3.3 0.601 0.700 46 38.3 0.701 -0 .800 40 33.3 0.801 0.900 23 19.2 0.901+ 7 5.8 total 120 100 maximum technical efficiency 0.60 minimum technical efficiency 0.50 mean technical efficiency 0.67 the frequency distribution of allocative efficiency estimate obtained from the stochastic frontier model is presented in table 5. this results indicates that majority (95.8%) of the farmers fall into the modal class (lowest class of about 30%) while the highest class (above 50%) were just about 0.8% with an average efficiency index of 13%. this could be because the little money that is being acquired by the farmer is spent on other household babatunde et al. efficiency of intercropping system in nigeria 5 expenditures as most were found with relatively large household sizes. also, only few of them have access to credit. this is in agreement with the findings of ghosh, 2004. table 5. allocative efficiencies of intercropping systems. allocative efficiency index frequency % <0.30 115 95.8 0.30-0.50 4 3.3 >0.50 1 0.8 total 120 100 minimum allocative efficiency 0.10 maximum allocative efficiency 0.84 mean allocative efficiency 0.13 4. conclusion and recommendations this study revealed that most of the farmers practicing intercropping were male. although smallholders were relatively technically efficient, they were not allocatively efficient. the farm size, quantity of fertilizer used and cost of other inputs determined the level of output in the intercropping system in the study. while membership of cooperative societies, household size and educational level were the factors that influence the level of technical inefficiencies of farmers. therefore, it is recommended that farmers be trained either through cooperative societies or organizing seminars on the advantages of practicing intercropping systems and the technique/skills involved. this may help the farmers to improve their allocative efficiency hence the quantity poduced most especially in the face of current climatic challenges and food security problems. 6. references abouziena, h.f. and haggag, w.m. 2016. weed control in clean agriculture: a review. planta daninha, 34(2): 377-392. agbongiarhuoyi a. e., aigbekaen e. o., adeogun s. o., uwagboe e. o., ndagi i. nd adebiyi s. 2012. “intercropping combination and information sources among kola farmers in osun state, nigeria”, journal of agricultural & food information, 13: (2): 169-179, doi: 10.1080/10496505.2012.664537 altieri m. a. 1999. applying agroecology to enhance productivity of peasant farming systems in latin america. environ dev sustain 1: 197–217 babatunde, r. o. and qaim, m. 2010. impact of offfarm income on food security and nutrition in nigeria. food policy, 35(4): 303-311 bifarin, j.o., alimi, t., baruwa, o.i. and ajewole, o. c. 2010. “determinant of technical, allocative and economic efficiencies in the plantain (musa spp.) production industry, ondo state, nigeria. proc. ic on banana & plantain in africa eds.: t. dubois et al. acta hort. 879: 199-210. brij, n. and anil, s. 2013. mitigating food security options through climate resilient mustard-maize based intercropping sequences for north-western himalayas. journal of food security 1 (2): 58-64 dordas, d. a. and damalas, c. a. 2011. forage yield, growth rate, and nitrogen uptake of faba bean intercrops with wheat, barley, and rye in three seeding ratios. crop science 50: 2148-2158. fao, 2011. save and grow: a new paradigm of agriculture. fao, rome. 102 pp. fukai s., trenbath b. r. 1993. processes determining intercrop productivity and yields of component crops. field crops res., 34: 247–271. ghosh l. s. 2004. growth, yield, competition and economics of groundnut/cereal fodder intercropping systems in the semi-arid tropics of india. field crops res 88: 227-237. godfray, c., beddington, j. r., crute, i. r., haddad, l., lawrence, d., muir, j. f., pretty, j., robinson, s., thomas, s. m., &toulmin, c,(2010) "food security: the challenge of feeding 9 billion people," science 327: 812-818. hauggard-nielson h, ambus p, jensen, e.s. 2001. evaluating pea andbarley cultivars for complementary in intercropping at different levels ofsoil n availability. field crops res., 72: 185-196. igbal, cheema and an. 2007. intercropping of field crops in cotton for the management of purple nutsedge (cyperusrotundus l.). plant soil 300: 163171. jane, v. 2006. histories of maize: multidisciplinary approaches to the prehistory, linguistics, biogeography, domestication, and evolution of maize. amsterdam. pp. 529–537 kassam, and friedrich, 2012. "an ecologically sustainable approach to agricultural production intensification: global perspectives and developments". field actions science reports. koohaffkan, p. and altieri, m. 2016. “forgotten agricultural heritage: reconnecting food systems and sustainable development”. a book published by routledge taylor and francis group. kumer, h. and pani, p. 2012. “effects of soil erosion on agricultural productivity in semi-arid regions: the case of lower chambal valley”. journal of rural development. 32: 165-184. lavabre, e. m. 1991. weed control. the tropical agriculturist. cta macmillian london pp 1-40. llewellyn r. s., ronning d., ouzman j., walker s., mayfield, a. and clarke, m. 2016. “impact of weeds on australian grain production: the cost of weeds to australian grain growers and the adoption of weed management and tillage practices”. report for grdc. csiro, australia. mangu, n., makate, c., hanyani-mlambo, b., siziba, s. and lundy m. 2015.“a stochastic frontier analysis of technical efficiency in smallholder maize production https://doi.org/10.1080/10496505.2012.664537 babatunde et al. east african journal of sciences volume 13 (1) 1-6 6 in zimbabwe: the post-fast-track land reform outlook.” cogent economics & finance, 3:1. narala, a. and zala, y. c. 2010. technical efficiency of rice farms under irrigated conditions in central gujarat. agricultural economics research review, 23: 375–381. nbs, 2006. national bureau of statistics, socioeconomic survey on nigeria, abuja okoye, b. c., onyenweaku, c. e. and asumugha, g. n. 2006. “allocative efficiency of small-holder cocoyam farmers in anambra state, nigeria. online at http://mpra.ub.uni-muenchen.de/17362/ mpra paper no. 17362 osun, adp 2012. osun state, nigeria. the intercropping systems commonly practiced in osun state are maize/cassava, maize/cassava/yam, cocoa/kolanut and cocoa/kolanut /palm tree. russell, a. e. 2002. relationship between crop-species diversity and soil characteristics in south-west indian agro-ecosystems. agro ecosystem environment 92: 235249. sanni, b. m., danmowa, n. m., sani, y. a. and jaliya, m. m. 2011. growth, yield and water use efficiency of maize-sorghum intercrop at samaru, northern guinea savannah, nigeria nigerian journal of basic and applied science, 19 (2): 253-259. ©haramaya university, 2022 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2022) volume 16(2): 133-154 licensed under a creative commons *corresponding author: gebremichaelaby@gmail.com attribution-noncommercial 4.0 international license. reliability of nasa nex-gddp dataset in reproducing climatological mean temperature and precipitation over the gibe iii watershed, omo-gibe basin, ethiopia abiy gebremichael 1, 2*, asfaw kebede2, and yali e. woyessa3 1bonga agricultural research center, southern agricultural research institute, kafa, ethiopia 2haramaya institute of technology, haramaya university, dire dawa, ethiopia 3department of civil engineering, central university of technology, free state, private bag x20539, bloemfontein, 9300, south africa abstract background: the challenge of climate variability is a major problem for developing and using water resources. scarcity of climate data compounds the problem and undermines the efforts to acquire updated information for predicting climate change and reduce its risks. objective: the objective of the study was to evaluate and select the best climate models having nasa earth exchange global daily downscaled projections (nex-gddp) dataset for gibe iii watershed. material and methods: nex-gddp data of precipitation and temperature with spatial resolution of 0.25º x 0.25º of ten cmip5 models was, evaluated against observed data of eight stations distributed in the watershed. results: the models showed a consistent and reasonable pattern for mean monthly total precipitation and mean temperature (max and min). the mean monthly precipitation of all models against observation also resulted to r2 of 0.71 to 0.99 and the nash–sutcliffe efficiency (nse) value of 0.66 to 0.99. mean annual precipitation of model ensemble mean over the watershed against observation spatially varied between –100 and 100 mm underestimating at the northern and southern tips of watershed while overestimating at central and northeastern parts. the mean maximum and minimum temperature varied from –1.6 ºc to +2.9 ºc and 0.4 ºc to 3.8 ºc, respectively. conclusion: the result indicates that, selecting climate models’ ensemble mean could provide higher confidence in climate change projection than choosing a specific model for an entire watershed. based on evaluation metrics and long-term mean annual rainfall, nex-gddp dataset of csiro-mk3-6-0, miroc5, mpi-esm-mr, noresm1-m, miroc5 and gfdl-esm2m models reasonably simulated the mean annual rainfall at shebe, sodo, jimma, hosaina, sokoru and woliso stations respectively for uses of climate change projection in the watershed. the reliability of nex-gddp dataset for the climate models need seasonal basis study in the future at the watershed since this study did not conduct seasonal data analysis. keywords: bias corrected; climatological mean; model ensemble mean; statistically downscaled 1. introduction studies on climate change impact on water resources require the use of climate models with higher resolution at local condition that could simulate the present day climate and give increased confidence on future climate scenarios (ramirez-villegas et al., 2013). these gcm projections have a spatial resolution (0.5º x 0.5º or more) (chu et al., 2010) that affect its application for climate change impact assessment at a local scale (ipcc, 2013). downscaling (jones et al., 2004; pervez and henebry, 2015) and bias correction of climate simulation models (ho et al., 2012) are major procedures when working with climate simulation models. dynamical downscaling technique (boé et al., 2006; christensen et al., 2006; jacob et al., 2014) and statistical downscaling technique (hewitson and crane, 2006; bosshard et al., 2013; maraun and widmann, 2018) were applied to downscale the gcm output to finer local climate conditions (dibike and mailto:gebremichaelaby@gmail.com abiy et al. east african journal of sciences volume 16(2): 133-154 134 coulibaly, 2005; frei et al., 2006; shimelis gebriye et al., 2010; wayne, 2013). gibe watershed has potential water resources for electric power generation at cascades of gibe i, ii, iii, and iv dam whose construction targeted before fifteen years (eepco, 2009). however, scarcity in climate data and the challenge of climate variability is a major problem for the gibe watershed hydrological resource basis which otherwise will not achieve its development goal (unep, 2013). the area needs updated information on the climate change impacts to reduce risks of climate change. downscaling of global-scale climatic variables to localscale hydrologic variables is an important procedure before perusing impact studies for climate change. however, as shimelis gebriye et al. (2010) explained, the limitation of downscaling procedure for getting climate model output is that it requires high computing resource capacity, high human knowledge and skill as well as time. in response to this problem, nasa produced earth exchange global daily downscaled projection (nex-gddp) dataset of coupled model intercomparison fifth project (cmip5) with resolution of 0.25º x 0.25º for climate models (thrasher et al., 2012; thrasher et al., 2015). chen et al. (2017) and jain et al. (2019) justified that the near and long-term climate study using the datasets was proved to be robust in regions with complex topography like the study region, gibe watershed, ethiopia. since gibe watershed is a source of hydroelectric power energy for the country, it needs a critical attention to sustain its service as planned. one of the information for such action is analysis of future climate state specially the rainfall and maximum and minimum temperature. on the other hand, studies on future climate condition and the prediction require use of climate models, which could show us plausible future climate. in this regard, it is important to compare some climate model outputs with existing observational dataset with historical data and use the best model that could represent the station climate data for future climate change as well as impact study. in this case, a comparative evaluation and selection of best climate models at omo-gibe basin in general and at gibe iii in particular was, not conducted. therefore, it is important to select best and high-resolution model type with nex-gddp dataset for the watershed through model reliability evaluation. accordingly, this study is signifies the importance of overcoming climate data scarcity and solve the uncertainty expected during climate change studies for sustainable management of water resources. the result will be of benefit to stakeholders who manage hydroelectric dams and its water sources as well as the scientific community for further research. the research question was, ‘is the existing bias corrected statistically downscaled high-resolution climate models with nex-gddp dataset applicable for use in gibe watershed’. therefore, the objective of the study was to evaluate the reliability of the nex-gddp datasets in reproducing climatological means of rainfall and temperature over gibe iii watershed 2. materials and methods 2.1. description of the study area gibe iii watershed is located within the omo-gibe river basin, in the middle reach of the omo river. it is located between the latitude of 6.6o–9.4on and longitude of 35.78o–38.42oe. the catchment area is about 34,154.16 km2 with the hydropower scheme comprising a 243 m high dam creating a reservoir of surface area spanning 200 km2 and creating storage of some 11,750 million m3 of water (eepco, 2009). gibe iii dam has the capacity to generate about 1870 mw (negash teklu et al., 2016) hydroelectric power. the area experiences hot arid to tropical humid and sub humid climatic conditions. the rainfall pattern is uni-modal for the northern and central parts of the watershed and bimodal for the southern part. the average annual rainfall calculated over the whole gibe iii watershed where the dam is located is 1,426 mm with major distribution occurring from may to september. the mean annual temperature varies from 16 oc to over 29 oc (eepco, 2009). the study area has a topography characterized by mountainous to hilly terrain and flat alluvial plain punctuated by hilly areas. the watershed has an altitude range of 681–3570 m a.s.l. (eepco, 2009). abiy et al. evaluating the of reliability of nasa nex-gddp dataset 135 figure 1. location of the gibe-iii watershed and weather stations (ethio-gis database). 2.2. data type and source the national aeronautics and space administration (nasa) earth exchange global daily downscaled projections (nex-gddp) dataset contains downscaled climate scenarios derived from the gcm simulations of the coupled model inter-comparison project phase 5 (cmip5). the spatial resolution of the dataset is 0.25° (~ 25 km × ~ 25 km). these datasets provide a set of global, high-resolution, biascorrected climate change projections that can be, used to evaluate climate change impacts on finer scales. each of the climate projections includes mean maximum and minimum temperatures and precipitation for the periods from 1950 to 2005 (retrospective run) and from 2006 to 2099 (prospective run) on a daily scale available at https://dataserver.nccs.nasa.gov/thredds/catalog/bypas s/nex-gddp/bcsd/catalog.html. the bias corrected statistically downscaled climate model output data of gcms with data range of 1976–2005 was, downloaded from nasa data portal (ftp://ftp.nccs.nasa.gov/). for comparative analysis, observed daily rainfall and maximum and minimum temperature data from 1976– 2005 was, obtained from national meteorological agency (nma) of ethiopia. eight climate stations in and around the watershed having full data similar to the selected model historical data period (1976–2005) were selected (table 1). table 1. data obtained from national meteorological agency for selected stations. stations lat. (degree) long. (degree) elev. (m.a.s.l) number of year period data type sokoru 7.92 37.42 1928 30 1976–2005 daily precipitation; daily maximum and minimum temperature atnago 8.31 36.95 1804 30 1976–2005 hosaina 7.57 37.85 2349 30 1976–2005 jimma 7.67 36.82 1718 30 1976–2005 nekemte 9.08 36.55 2108 30 1976–2005 shebe 7.50 36.52 1772 30 1976–2005 sodo 6.81 37.73 2032 30 1976–2005 woliso 8.55 37.98 2464 30 1976–2005 2.3. methods 2.3.1. climate model selection the following table indicates the list of selected cmip5 climate models for this study (table 2). however, due to limitation of time for analysis of each variable on a station basis, from twenty-one models developed in different countries at different institutions, the study selected only about ten models. the researcher https://dataserver.nccs.nasa.gov/thredds/catalog/bypass/nex-gddp/bcsd/catalog.html https://dataserver.nccs.nasa.gov/thredds/catalog/bypass/nex-gddp/bcsd/catalog.html ftp://ftp.nccs.nasa.gov/ abiy et al. east african journal of sciences volume 16(2): 133-154 136 downloaded historical daily precipitation and maximum and minimum temperature data for each point-station from nasa web page. table 2. information about the selected 10 coupled model inter-comparison fifth project (cmip5) general circulation models (gcms). number model country and institution 01 access1-0 1 commonwealth scientific and industrial research organization and bureau of meteorology, australia 02 canesm2 canadian centre for climate modelling and analysis, canada 03 cnrm-cm5 centre europeen de recherche et formation avanceesencalculscientifique, france 04 csiro-mk3-6-0 commonwealth scientific and industrial research organization queensland climate change centre of excellence, australia 05 gfdl-esm2m geophysical fluid dynamics laboratory, america 06 ipsl-cm5a-lr institute pierre-simon laplace, france 07 miroc5 atmosphere and ocean research institute, japan 08 mpi-esm-mr max planck institute for meteorology, germany 09 mri-cgcm3 max planck institute for meteorology, germany 10 noresm1-m norway consumer council, norway in order to analyze the data on a watershed basis, area weighted data were prepared for average annual precipitation and temperature using inverse distance weight (idw), the method recommended by chen and liu (2012) for spatial interpolation using arcgis version 10.1. idw is a common and simple way of spatial interpolation, where observations are weighted based on their distance to a given point by a non-linear relationship expressed by an exponent (typically equal to 2). the method is widely used due to its simplicity and its applicability to even sparse and irregular datasets (ahrens, 2006; yang et al., 2015). idw uses the distances from the target neighbor gauge stations with more weight given to data of nearest station as justified by different authors (longley et al., 2001; de silva et al., 2007; achilleos, 2011; chen and liu, 2012; moeletsi et al., 2016). monthly patterns of precipitation and temperature were plotted against the observation for the monthly long-term mean data of the selected models. 2.3.2. performance metrics for evaluation of models the performance metrices, such as the root mean squared error (rmse), coefficient of determination (r2), and nash–sutcliffe efficiency (nse) of the annual mean precipitation (ma-p), the mean monthly temperature (mm-tboth max. and min) as well as mean monthly precipitation (mm-p) (nash and sutcliffe, 1970; maclean, 2005) were applied during statistical analysis (equations 1-3). in addition, absolute (ae) and relative errors (re) were used to identify models that could reasonably reproduce the mean annual precipitation (map) at each station so that the station would get one representative model. the smaller the ae or re, the better is the model to reproduce the observation (equations 4 and 5). these metrics were used as the indicators for the performance comparison of each model with observed data. r2 shows the degree of the linear relation between model output and observed data; r2 of 0 denotes no relation whereas 1 represents strong relation. rmse represents the errors between two variables; the smaller the rmse, the better the results. the specific performance metrics including mean annual precipitation (mean-p) and mean annual temperature (mean-t) were also used during the evaluation. 𝑅2 = [ 1 n ∑ (xo n m=1 −μo)(xm−μm) σxo x σxm ] 2 eq. 1 𝑅𝑀𝑆𝐸 = √ ∑ (xo−xm) 2𝑛 𝑚=1 𝑛 eq. 2 𝑁𝑆𝐸 = 1 − [ ∑ (𝑌𝑖 𝑜𝑏𝑠 −𝑌𝑖 𝑠𝑖𝑚)2 𝑛 𝑖=1 ∑ (𝑌𝑖 𝑜𝑏𝑠 −𝑌𝑚𝑒𝑎𝑛)2𝑛𝑖=1 ] eq. 3 where, x, μ and σ show the raw data, mean and variance, respectively, while o and m show the observed and model, respectively, and n is the number of events. 𝐴𝑏𝑠𝑜𝑙𝑢𝑡𝑒 𝐸𝑟𝑟𝑜𝑟 (𝐴𝐸) = |𝑦𝑚𝑒𝑎𝑛 𝑜𝑏𝑠 − 𝑦𝑚𝑒𝑎𝑛 𝑚𝑜𝑑𝑒𝑙 | eq. 4 𝑅𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝐸𝑟𝑟𝑜𝑟 (𝑅𝐸) = |𝑦𝑚𝑒𝑎𝑛 𝑜𝑏𝑠−𝑦𝑚𝑒𝑎𝑛 𝑚𝑜𝑑𝑒𝑙| 𝑦𝑚𝑒𝑎𝑛 𝑜𝑏𝑠 𝑥100 eq. 5 abiy et al. evaluating the of reliability of nasa nex-gddp dataset 137 where, 𝑦𝑚𝑒𝑎𝑛 𝑜𝑏𝑠 = long-term mean (1976-2005) of the observation of annual precipitation at station and 𝑦𝑚𝑒𝑎𝑛 𝑚𝑜𝑑𝑒𝑙 = long-term mean (1976-2005) of the model of annual precipitation at station 3. results knowledge of historical climate condition compared to model outputs from different sources of data has an important role to play in building confidence in the knowledge of future climate change simulated by such models. although gcms are a very important source of information to know the future climate, uncertainty due to their inherent characteristics, the complexity of variables (parameters) producing atmospheric and land system interaction requires evaluation of their output based on observation data. thus, precipitation and temperature analyses for ten models, ensemble mean of the models and observation data were, carried out and the results are discussed below. 3.1. performance of nex-gddp dataset for simulating mean monthly temperature the mean monthly maximum and minimum temperatures of each model and ensemble mean as well as for observation in selected weather stations are shown in figure 2. figure 2. climatological (1976–2005) annual cycle (monthly mean) of surface temperature (maximum (left) and minimum (right) of nex gddp model historical and observed data (a-p). 0 5 10 15 20 25 30 35 1 2 3 4 5 6 7 8 9 10 11 12 m ax t e m p ( o c ) months canesm2 _csiro-mk3-6-0 miroc5 gfdl-esm2m ipsl-cm5a-lr noresm1-m mpi-esm-mr mri-cgcm3 access1-0 cnrm-cm5 ensemble obserbed b) sodo tmax 0 5 10 15 20 1 2 3 4 5 6 7 8 9 10 11 12 m in t e m p ( o c ) months canesm2 miroc5 gfdl-esm2m ipsl-cm5a-lr noresm1-m csiro-mk3-6-0 mpi-esm-mr mri-cgcm3 access1-0 cnrm-cm5 ensemble observed b) sodo tmin 0 5 10 15 20 25 30 1 2 3 4 5 6 7 8 9 10 11 12 m ax . t e m p ( o c ) months canesm2 csiro-mk3-6-0 miroc5 gfdl-esm2m ipsl-cm5a-lr noresm1-m access1-0 mpi-esm-mr mri-cgcm3 cnrm-cm5 enseble observed c) shebe tmax 0 10 20 1 2 3 4 5 6 7 8 9 10 11 12 m in . t e m p ( o c ) months canesm2 csiro-mk3-6-0 miroc5 gfdl-esm2m ipsl-cm5a-lr noresm1-m mpi-esm-mr mri-cgcm3 cnrm-cm5 access1-0 d) shebe tmin abiy et al. east african journal of sciences volume 16(2): 133-154 138 [[ figure 2. continued. 0 5 10 15 20 25 30 1 2 3 4 5 6 7 8 9 10 11 12 m ax t e m p ( o c ) months e) woliso tmax 0 5 10 15 1 2 3 4 5 6 7 8 9 10 11 12 m in t e m p ( o c ) months f) woliso tmin 0 5 10 15 20 25 30 35 1 2 3 4 5 6 7 8 9 10 11 12 m ax t e m p ( o c ) months canesm2 csiro-mk3-6-0 miroc5 noresm1-m gfdl-esm2m ipsl-cm5a-lr mpi-esm-mr mri-cgcm3 access1-0 cnrm-cm5 ensemble obseved g) nekemite tmax 0 5 10 15 1 2 3 4 5 6 7 8 9 10 11 12 m in . t e m p ( o c ) months canesm2 csiro-mk3-6-0 miroc5 noresm1-m gfdl-esm2m ipsl-cm5a-lr mpi-esm-mr mri-cgcm3 access1-0 cnrm-cm5 ensemble obseved h) nekemite tmin 0 5 10 15 20 25 30 1 2 3 4 5 6 7 8 9 10 11 12 m ax t e m p ( o c ) months canesm2 csiro-mk3-6-0 gfdl-esm2m noresm1-m ipsl-cm5a-lr access1-0 cnrm-cm5 mpi-esm-mr miroc5 mri-cgcm3 essemble model observed i) sekoru tmax 0 5 10 15 1 2 3 4 5 6 7 8 9 10 11 12 m x t e m p ( o c ) months canesm2 csiro-mk3-6-0 gfdl-esm2m noresm1-m ipsl-cm5a-lr access1-0 cnrm-cm5 miroc5 mpi-esm-mr mri-cgcm3 essemble model observed j) sekoru tmin abiy et al. evaluating the of reliability of nasa nex-gddp dataset 139 3.2. performance of nex-gddp dataset for simulating mean monthly distribution pattern of precipitation the results of comparing the ten cmip5 models with nex-gddp dataset outputs, their ensemble mean and observed data of monthly distribution from (1976–2005) of rainfall data for eight weather stations is shown in figure 3 below. as in the case of temperature, the precipitation pattern was similar among ten models and the ensemble mean. although bar graphs show the magnitude of precipitation for all ten models, to make the document simple to readers, only model ensemble mean and observed value were, made visible by line graph overlay. figure 3. climatological (1976–2005) mean monthly total precipitation at each station for nex_gddp dataset, the ensemble mean of 10 models and observed data 0 50 100 150 200 250 300 350 1 2 3 4 5 6 7 8 9 10 11 12 r ai n fa ll ( m m ) months canesm2 csiro-mk3-6-0 miroc5 noresm1-m ipsl-cm5a-lr gfdl-esm2m mpi-esm-mr mri-cgcm3 cnrm-cm5 access1-0 essemble model observed a) atnago station 0 100 200 300 400 500 1 2 3 4 5 6 7 8 9 10 11 12 r ai n fa ll ( m m ) months canesm2 csiro-mk3-6-0 miroc5 noresm1-m ipsl-cm5a-lr gfdl-esm2m mpi-esm-mr mri-cgcm3 cnrm-cm5 access1-0 ensemble observed b) nekemite station abiy et al. east african journal of sciences volume 16(2): 133-154 140 figure 3. continued 0 50 100 150 200 1 2 3 4 5 6 7 8 9 10 11 12 r ai n fa ll ( m m ) month canesm2 csiromk noresm1m miroc5 ipslcm5alr gfdlesm2m mpiesmmr mricgcm3 access10 cnrmcm5 ensemble observed c) sodo station 0 50 100 150 200 250 1 2 3 4 5 6 7 8 9 10 11 12 r ai n fa ll ( m m ) months access1-0 canesm2 cnrm-cm5 csiro-mk3-6-0 gfdl-esm2m ipsl-cm5a-lr miroc5 mri-cgcm3 mpi-esm-mr noresm1-m observed ensemble d) sokoru station 0 50 100 150 200 250 1 2 3 4 5 6 7 8 9 10 11 12 r ai n fa ll ( m m ) months canesm2 csiro-mk3-6-0 miroc5 noresm1-m ipsl-cm5a-lr gfdl-esm2m mpi-esm-mr mri-cgcm3 cnrm-cm5 access1-0 essemble model observed e) hosaina station abiy et al. evaluating the of reliability of nasa nex-gddp dataset 141 figure 3. continued. the climatological (1976–2005) mean monthly model outputs of precipitation was also subjected evaluation metrics such as rmse, r2 and nse and the result is indicated in table 3 0 50 100 150 200 250 300 1 2 3 4 5 6 7 8 9 10 11 12 r ai n fa ll ( m m ) month canesm2 noresm1-m csiro-mk3-6-0 gfdl-esm2m miroc5 cnrm-cm5 mpi-esm-mr mri-cgcm3 access1-0 ipsl-cm5a-lr ensemble model observed f) jima station 0.0 100.0 200.0 300.0 400.0 1 2 3 4 5 6 7 8 9 10 11 12 r ai n fa ll ( m m ) month noresm1-m canesm2 gfdl-esm2m miroc5 csiro-mk3-6-0 ipsl-cm5a-lr access1-0 cnrm-cm5 mri-cgcm3 mpi-esm-mr ensemble observed 0 50 100 150 200 250 300 1 2 3 4 5 6 7 8 9 10 11 12 r ai n fa ll ( m m ) month canesm2 csiro-mk3-6-0 miroc5 gfdl-esm2m ipsl-cm5a-lr noresm1-m mpi-esm-mr mri-cgcm3 cnrm-cm5 access1-0 ensemble observed h) shebe station g) woliso station abiy et al. east african journal of sciences volume 16(2): 133-154 142 table 3. performance metrics for climatological mean monthly precipitation total models outputs relative to observation at the station. metrics canesm2 csiromk3-6-0 miroc5 ipslcm5alr gfdlesm2m noresm1m mpiesmmr mricgcm3 access10 cnrmcm5 ensemble max min mean sokoru station rmse 20.75 20.53 17.95 24.38 32.63 29.57 15.12 20.60 30.61 25.63 16.84 32.63 15.12 23.2 r2 0.92 0.93 0.94 0.93 0.83 0.84 0.97 0.93 0.84 0.91 0.95 0.97 0.83 0.91 nse 0.95 0.95 0.96 0.93 0.87 0.89 0.97 0.95 0.89 0.92 0.97 0.97 0.87 0.93 atnago station rmse 38.72 42.29 37.65 41.41 35.79 43.16 42.52 38.28 41.02 42.66 39.47 43.16 35.79 40.3 r2 0.96 0.97 0.97 0.96 0.99 0.98 0.98 0.98 0.95 0.95 0.98 0.99 0.95 0.97 nse 0.86 0.84 0.87 0.84 0.88 0.83 0.84 0.87 0.85 0.83 0.86 0.88 0.83 0.85 hosaina station rmse 26.52 24.15 22.53 23.98 27.16 19.75 25.07 22.12 21.31 28.78 22.21 28.78 19.75 23.9 r2 0.83 0.88 0.88 0.87 0.84 0.89 0.86 0.86 0.9 0.81 0.88 0.9 0.81 0.86 nse 0.78 0.82 0.84 0.82 0.77 0.88 0.8 0.85 0.86 0.74 0.84 0.88 0.74 0.82 jima station rmse 13.54 12.74 12.64 14.45 15.12 14.51 11.97 10.45 15.17 16.12 8.64 16.12 8.64 13.2 r2 0.97 0.97 0.98 0.98 0.97 0.97 0.98 0.98 0.96 0.96 0.99 0.99 0.96 0.9 nse 0.96 0.96 0.97 0.95 0.95 0.95 0.97 0.98 0.95 0.94 0.98 0.98 0.94 0.96 nekemte station rmse 52.84 54.04 53.84 55.43 57.06 58.63 52.77 49.97 55.61 59.82 53.88 59.82 49.97 54.9 r2 0.99 0.98 0.98 0.98 0.97 0.98 0.99 0.99 0.97 0.99 0.99 0.99 0.97 0.98 nse 0.85 0.85 0.85 0.84 0.83 0.82 0.85 0.87 0.84 0.81 0.85 0.87 0.81 0.84 sodo station rmse 19.34 16.03 19.43 20.59 20.98 18.31 17.72 16.05 17.62 19.54 14.9 20.98 14.9 18.2 r2 0.96 0.97 0.97 0.98 0.97 0.98 0.97 0.98 0.97 0.95 0.99 0.99 0.95 0.97 nse 0.91 0.94 0.91 0.9 0.89 0.92 0.92 0.94 0.92 0.91 0.95 0.95 0.89 0.92 shebe station rmse 30.78 33.71 31.38 24.19 23.21 27.11 33.32 33.4 29.99 29.75 28.92 33.71 23.21 29.6 r2 0.77 0.79 0.73 0.85 0.88 0.8 0.78 0.71 0.79 0.77 0.84 0.88 0.71 0.79 nse 0.71 0.66 0.7 0.82 0.84 0.78 0.66 0.66 0.73 0.73 0.75 0.84 0.66 0.73 woliso station rmse 23.36 20.64 24.79 17.28 26.68 26.11 9.63 17.22 28.13 13.29 16.33 28.13 9.63 20.3 r2 0.95 0.95 0.95 0.97 0.92 0.93 0.99 0.97 0.91 0.98 0.97 0.99 0.91 0.95 nse 0.86 0.95 0.93 0.96 0.91 0.92 0.99 0.96 0.9 0.98 0.97 0.99 0.86 0.94 note: this table is the output of statistical analysis of selected model climatological mean monthly values relative to observed values for each station. sample analysis for sokoru station was shown in appendix table 2. abiy et al. evaluating the of reliability of nasa nex-gddp dataset 143 3.3. performance of nex-gddp dataset for simulating climatological mean annual precipitation distribution and magnitude the annual precipitation result for ten models, the ensemble mean and observed data over selected eight stations of the watershed is demonstrated in figure 4. figure 4. climatological mean annual rainfall distribution for models and observation. 1000 1200 1400 1600 a c c e s s 1 -0 c an e s m 2 c n r m -c m 5 c s ir o -… g f d l -… ip s l -… m ir o c 5 m p ie s m -… m r ic g c m 3 n o re s m 1 -m e ss e m b le … o b se rv ed a n n . ra in fa ll ( m m ) models jima station 1000 1200 1400 1600 1800 a c c e s s 1 -0 c a n e s m 2 c n r m -c m 5 c s ir o -… g f d l -… ip s l -… m ir o c 5 m p ie s m -… m r ic g c m 3 n o re s m 1 -m e n se m b le o b se rv e d a n n . ra in fa ll ( m m ) models shebe station 1000 1100 1200 1300 1400 1500 1600 1700 1800 a c c e s s 1 -0 c an e s m 2 c n r m -… c s ir o -… g f d l -… ip s l -… m ir o c 5 m p i… m r i… n o re s m … e ss e m b le o b se rv ed a n n . ra in fa ll ( m m ) models atnago station 1000 1200 1400 1600 1800 2000 a c c e s s 1 -0 c an e s m 2 c n r m -c m 5 c s ir o -m k 3 -6 -0 g f d l -e s m 2 m ip s l -c m 5 a -l r m ir o c 5 m p ie s m -m r m r ic g c m 3 n o re s m 1 -m e ss e m b le m o d e l o b se rv ed a n n . ra in fa ll ( m m ) models nekemite station 1000 1100 1200 1300 1400 1500 a c c e s s 1 -0 c an e s m 2 c n r m -c m 5 c s ir o -m k 3 -6 -0 g f d l -e s m 2 m ip s l -c m 5 a -l r m ir o c 5 m r ic g c m 3 m p ie s m -m r n o re s m 1 -m e ss e m b le o b se rv ed a n n . ra in fa ll ( m m ) sokoru station 1000 1060 1120 1180 1240 a c c e s s 1 -0 c an e s m 2 c n r m -c m 5 c s ir o -… g f d l -… ip s l -… m ir o c 5 m p ie s m -m r m r ic g c m 3 n o re s m 1 -m e ss e m b le … o b se rv ed a n n . ra in fa ll ( m m ) models hosaina station abiy et al. east african journal of sciences volume 16(2): 133-154 144 figure 4. continued. the mean standard deviation and coefficient of variation indicated in table 4 was obtained for each variables (mean annual precipitation and mean maximum and minimum temperture for each station. the analysis is to identify the variability between models and observation in eneral. table 4. the mean, standard deviation (sd) and coefficient of variation (cv) for climatological means of models and observation at each station. station mean annual precipitation for models and observation mean annual maximum temperature for models and observation mean annual minimum temperature for models and observation mean sd cv (%) mean sd cv (%) mean sd cv (%) atnago 1394.59 86.66 6.21 26.59 0.32 1.22 12.98 0.22 1.66 nekemte 1407.07 101.54 7.22 24.88 0.29 1.17 12.28 0.16 1.33 sodo 1165.09 37.09 3.18 26.77 0.64 2.38 11.70 0.72 6.15 shebe 1497.15 37.71 2.52 23.68 0.65 2.73 10.01 0.99 9.91 hosaina 1534.36 41.25 9.21 23.91 0.51 2.13 9.76 0.34 3.46 jimma 1571.40 45.91 2.92 25.54 0.57 2.24 11.22 0.16 1.42 woliso 1158.60 65.04 5.61 23.99 0.39 1.64 10.64 0.66 6.21 sokoru 1348.44 56.85 4.22 24.45 0.87 3.56 10.28 0.62 5.99 tables 5 and 6 show absolute error and relative error of each model at each station. the climatological mean annual precipitation indicated in appendix table 3 and equations 4 and 5 was the source of data for caluculation of ae and re. shaded values indicate the minimum values of the model at respective station and it shows the model to be selected at the station. table 5. the absolute error for climatological mean annual precipitation of models relative to observation at each station. name of station canes m2 csiromk3-60 miro c5 ipslcm5a-lr gfdlesm2m nores m1-m mpiesmmr mricgc m3 acce ss1-0 cnr mcm5 sokoru 54.0 43.7 6.2 139.8 93.3 39.0 59.7 74.3 85.1 57.3 atnago 335.5 362.4 316.0 337.1 371.9 322.6 386.7 333.6 318.8 354.5 hosan 79.3 111.7 80.4 44.3 57.3 15.6 115.7 32.6 99.2 88.1 jimma 15.2 35.9 20.1 39.1 24.9 108.9 3.9 31.9 22.6 26.1 nekemte 484.1 456.0 485.9 508.2 511.3 451.0 473.6 431.1 449.5 535.4 shebe 18.7 10.8 31.8 73.3 60.3 152.8 39.5 65.5 63.8 15.9 sodo 159.3 248.6 93.2 111.8 135.3 122.6 227.7 141.0 172.9 126.9 woliso 111.8 58.5 147.9 47.8 4.7 50.8 49.3 98.9 79.8 72.4 1000 1100 1200 1300 1400 a c c e s s 1 -0 c an e s m 2 c n r m -c m 5 c s ir o -… g f d l -… ip s l -… m ir o c 5 m p ie s m -m r m r ic g c m 3 n o re s m 1 -m e ss e m b le o b se rv eda n n . ra in fa ll ( m m ) models sodo station 1100 1200 1300 1400 a c c e s s 1 -0 c an e s m 2 c n r m -… c s ir o -… g f d l -… ip s l -… m ir o c 5 m p i… m r i… n o re s m 1 … e ss e m b le o b se rv ed a n n . ra in fa ll ( m m ) models woliso station abiy et al. evaluating the of reliability of nasa nex-gddp dataset 145 table 6. the relative error (%) for long-term mean annual precipitation of models relative to observation at each station. station canes m2 csiromk3-6-0 miroc 5 ipslcm5a-lr gfdlesm2m noresm 1-m mpiesm-mr mricgcm3 acce ss1-0 cnrmcm5 sokoru 4.1 3.3 0.5 10.7 7.1 3.0 4.6 5.7 6.5 4.4 atnago 19.5 21.0 18.4 19.6 21.6 18.7 22.5 19.4 18.5 20.6 hosain 6.4 9.1 6.5 3.6 4.7 1.3 9.4 2.7 8.1 7.2 jimma 1.0 2.4 1.4 2.6 1.7 7.3 0.3 2.2 1.5 1.8 nekemte 24.5 23.1 24.6 25.8 25.9 22.9 24.0 21.8 22.8 27.1 shebe 1.2 0.7 2.1 4.8 4.0 10.0 2.6 4.3 4.2 1.0 sodo 12.2 19.1 7.2 8.6 10.4 9.4 17.5 10.8 13.3 9.7 woliso 9.0 4.7 12.0 3.9 0.4 4.1 4.0 8.0 6.5 5.9 3.4. performance of nex-gddp dataset for simulating spatial variability of mean annual precipitation and temperature the model ensemble mean annual rainfall was spatially, interpolated to the watershed area for comparative analysis with the observed values. spatial basis distributions of the nasa dataset (1976–2005) mean annual precipitation and temperature are displayed in figure 5. figure 5. spatial distributions of the climatological mean annual precipitation (1976–2005) (a) observed, (b) ensemble mean of 10 models for the watershed. abiy et al. east african journal of sciences volume 16(2): 133-154 146 figure 6. spatial distributions of the climatological mean annual surface temperatures (1976–2005) for observed and the ensemble mean of 10 models for mean maximum temperature (a and b) and minimum temperature (c and d) of the watershed. 4. discussion 4.1. performance of nex-gddp dataset for simulating mean monthly temperature the mean monthly maximum and minimum temperatures of the models were not significantly different to each other in the respective stations (figure 2). however, the difference was, obviously observed between observation and ensemble mean. in all stations, mean maximum temperature of ten models and ensemble mean had a similar pattern of observation. however, the mean minimum temperature had a similar pattern of observation only at sokoru, jimma, shebe, nekemte, and atnago. during the months from october to march, mean minimum temperatures at sodo, hosaina and woliso stations were not captured by all models and indicating the underestimation of mean minimum temperature. dyer et al. (2019) justified that, cold biases from november–march are a common characteristic of almost all of the coupled model climatology in some parts of ethiopia. the author explained that if the models cannot reproduce higher temperatures in the months of dry season, they might not be a useful tool for using in such event prediction. the best fit of the lines (pattern) among the models and their ensemble mean for mean maximum and minimum temperature at the remaining stations indicates the possibility of using one of the models data or ensemble mean data for further studies in this watershed. the climatological mean monthly maximum temperature was little overestimated at sodo and hosaina while it was underestimated at shebe, jima and sokoru stations. according to randall et al. (2007), the local topography, existing surface condition and the weather events can make variations among stations. regions with sharp elevation changes that could come from mismatches between the smoothed model topography and the actual topography of area can result in larger errors. this situation is in agreement with justification of dyer et al. (2019) who stated that the highland in general is cooler so that the models may not be able to capture the spatial heterogeneity in regional temperature. the climatological mean monthly temperature patterns in figure 2 clearly indicates how well the nex-gddp model runs and reproduces observed annual cycle. generally, five out of eight stations shown at figure 2 indicated good simulation ability of nex-gddp model datasets for gibe watershed to reproduce the observed temperature. abiy et al. evaluating the of reliability of nasa nex-gddp dataset 147 4.2. performance of nex-gddp dataset for simulating mean monthly distribution pattern of precipitation there was a good match of mean monthly precipitation total (climatological mean monthly precipitations) pattern in all cases between models, their ensemble means and observed values. in stations such as atnago (figure 3a), nekemte (figure 3b), and sodo (figure 3c), the models failed to capture the higher magnitude of the observations during the months of may to september so that, the mean was underestimated. this situation was explained by to randall et al. (2007) since the models continue to have significant limitations in their representation of clouds that could lead to uncertainties in the magnitude and timing of precipitation. though nex-gddp dataset is bias-corrected, it underestimates rainfall observation which might result in uncertainties especially from high discrepancies in the extreme values of precipitation (bao and wen, 2017; raghavan et al., 2018). however, dettinger et al. (2004) and wilby et al. (2000) agreed that, the performance of model outputs with nex-gddp data were applicable in hydro-climatology studies under data scarce conditions. the peak and trough for the magnitude of the annual cycle were kept in a similar trend for all models against the observation though there could be a limitation in the inherent uncertainties in the models. the result is supported by the findings of dyer et al. (2019), raghavan et al. (2018) and tierney et al. (2015) that nex-gddp reproduced the observed patterns except for some marginal differences in the rainfall magnitude during wet months. the result indicates that nexgddp dataset can be applicable with better confidence during station based climate change impact study as the nex-gddp data represents well the mean states of temperature and precipitation on a monthly scale. several studies adopted the bias correction and spatial disaggregation (bcsd) method to assess the hydrological impacts of climate change (payne et al., 2004; vanrheenen et al., 2004; hayhoe et al., 2006). 4.3. performance metrics for climatological mean monthly precipitation total from table 3, it is clear that, the selected models of the nex-gddp dataset reproduced the observed mean monthly total precipitation better based on the acceptance level of metrics used in evaluation. the evaluation metrics resulted in r2 of 0.71–0.99; nse of 0.66-0.99 and rmse of 8.64–59.82mm for different models at eight stations. in eight stations, nse value ranged from 0.66 at shebe station for the csiro-mk3-60 model to 0.99 at woliso station for the mpi-esm-mr model indicating strong relation to the observed value since a value of nse greater than 0.5 is generally at acceptable level of performance (nash and sutcliffe, 1970). the higher rmse (59.82 mm) was obtained from cnrm-cm5 model (nekemte station) while the lower rmse (8.64 mm) was observed at the model ensemble at jimma station. multi model ensemble of these ten models (figure 3) shows that mean monthly observations for june, july, august and september were highly underestimated at atnago, nekemte and sodo stations with maximum difference at july by about 80–100mm of rainfall. these stations are at boundary divide of watershed (sodo and atnago) and outside the watershed (nekemte) at high elevation (figure 1). on the other hand, at hosaina station, march april and may were, underestimated while june, july and august were, overestimated slightly. on the contrary, all models captured dry periods in all stations correctly. it can be justified that the models well captured rainfall pattern at shebe, jimma, sokoru and woliso stations for all selected models. it could be argued that the detail agricultural water management requires nexgddp dataset selection on seasonal bases because obvious biases were observed in the seasonal values, which are also not uniform in space amongst models. the justification by kug et al. (2008), sengupta and rajeevan (2013) and jain et al. (2019) supports this argument. the result indicates that the nasa dataset of monthly scale could help during the prediction of the rainfall simulation in the future. according to alo and wang (2010), the statistical downscaling with bias correction is an effective tool to derive fine resolution predictions directly from coarse resolution gcms' outputs. 4.4. performance of nex-gddp dataset for simulating mean annual precipitation distribution and magnitude station based comparision indicated that the observed mean annual rainfall was reproduced for jimma and shebe stations except for the case of noresm1-m which is overestimated by about 100 mm per year. generally, the mean annual precipitation showed high mismatch at stations such as hosaina, sodo, nekemte and atnago resulting to underestimation of observation by 100–300 mm annual rainfall. on the contrary, overestimation was observed at sokoru and woliso by 50–80 mm per year. underestimations of the mean annual precipitation by the models were observed for northern (atnago and nekemte) tip of the study area and overestimations were abiy et al. east african journal of sciences volume 16(2): 133-154 148 observed for central (sokoru and woliso) areas of the study. however, unpredictable condition of mean annual precipitation was seen among the models in south-east (hosaina and sodo) of study watershed. the results agree with the findings of mcmahon et al. (2015) who reported that, the performance statistics comparing cmip5 gcm outputs and observed mean annual precipitation showed that the high mean annual precipitation was underestimated and the low mean annual precipitation was overestimated. according to ahmed et al. (2013), the drawback of the models, however, is that many wet days are set to no-rain days, which leads to a slight underestimation of the amount of rain. it was also justifed by raghavan et al. (2018) that the magnitude of precipitation in the inter-annual variability is underestimated by nex-gddp compared to the observation. this is because the frequency and mangnitude of annual daily maximum events in obsevations may be higher than that of the model. precipitation is one of the ckimate varaibles that is the mist challengimng for modelling due to the low predictability especially a topographically complex region (wilby and dawson, 2007). acoording to jain et al. (2019), the nex-gddp information biases with observed data at 25 km horizontal resolution could be due to the lack of ability of the model parameterization schemes to deal with mountainous regions. atnago and nekemte stationss overall variability or mean annual precipitation was high among models including observation with sd of 86.66 and 101.54 respectively. in addition, the mean monthly and annual precipitation of all models tested at these two stations did not reasonably capture the observation. tables 5 and 6 also confirm the condition that the absolute error for all models is above 300 mm. the cause may be the microclimate effect, which was not parameterized in the models. based on the performance metrics (tables 3, 4, 5 and 6) as well as the magnitude of the station based long-term mean annual precipitation (figure 4) atnago and nekemte stations could be out of stations to use nex-gddp dataset. the results shown in tables 5 and 6 indicated that nex-gddp dataset of csiro-mk3-60, miroc5, mpi-esm-mr, noresm1-m, miroc5 and gfdl-esm2m models reasonably simulated the mean annual rainfall at shebe, sodo, jimma, hosaina, sokoru and woliso stations, respectively. 4.5. performance of nex-gddp dataset for simulating spatial variability of annual precipitation and temperature the results of maps from nex-gddp data showed a similar trend of distribution against the observation in the catchment with small variation in magnitude. from figure 5, it is observed that, the major coverage of variability of observed data from model output is in the range of -100 to 100 mm per year. from the spatial information, the nex-gddp could capture the pattern of precipitation but not the magnitude of precipitation. the result indicates underestimation of the annual precipitation by the models at the northern and southern tips of the watershed while overestimation at sokoru (central watershed) and woliso (northeast tip) of the study area. given the complexity of variables in modeling precipitation, existence of limitations in downscaling technique, data scarcity problem in the region (thrasher et al., 2015) and topographic effect of the microclimate in the study area, the results obtained can be tolerable and could be used to evaluate the impact of climate change on water resource in the study area. the spatial distribution of the mean annual maximum and minimum temperatures for the watershed (figure 6) was observed not to be consistent with the variations in the rainfall of selected stations. the maximum temperature is overestimated by the model at the northern tip, southern tip, and the southeastern tip of the watershed while it was underestimated by 1.2–2.9 ºc at the central and towards the western part of the study area. however, the magnitude of the difference is very small (0.6–1.2 ºc) for major coverage of the area. the minimum values were overestimated while the maximum values were underestimated. regarding the minimum temperature (figure 6), small coverage of land showed underestimation by about 2.4–3.8 ºc difference at the southern tip and the western tip. a larger portion of the watershed got little variation from 0.4–2.4 ºc difference (mean 1.4 ºc). 5. conclusion and recommendation study of the impact of climate change on water resource at local scale requires reliable and bias corrected high resolution, climate model output. bcsd nex-gddp dataset of daily precipitation and temperature having spatial resolution of 25km was released by nasa for use in data scarce regions. accordingly, these dataset were not evaluated for their reliability for application in gibe iii watershed. thus, the climatological means of precipitation and temperature (1976–2005) from ten abiy et al. evaluating the of reliability of nasa nex-gddp dataset 149 climate models were comparatively evaluated with observed data at selected representative stations of gibe iii watershed. the nex-gddp dataset of the most of the stations reasonably reproduced the pattern of the climatological annual cycles (monthly means) for temperature and precipitation. however, the climatological mean monthly minimum temperature at sokoru, shebe and woliso showed underestimation while the mean monthly precipitation at atnago, nekemte and sodo also resulted to underestimation. although different metrics were applied to evaluate and select the relative model that could capture the observation at each station, r2 value greater than 0.71; nse value more than 0.66 and rmse lower than 59.82 mm were recorded by the different models at each station for climatological mean monthly total values. from all models in the eight stations, the lowest nse value of 0.66 at shebe station for csiro-mk3-6-0 model and the higher nse of 0.99 at woliso station for the mpi-esm-mr model indicated the strong relation of the models to observed values. the highest rmse (59.82 mm) was obtained at the cnrmcm5 model (nekemte station) while the lower rmse (8.64mm) was observed at ensemble mean at jimma station which indicate nex-gddp dataset of one single model may not be applicable for different locations. the findings indicted that the six stations had likely representative model that simulated climatological mean monthly and mean annual rainfall as well as temperature (max. and min). accordingly, based on evaluation metrics and long-term mean annual rainfall, nex-gddp dataset of csiro-mk3-6-0, miroc5, mpi-esm-mr, noresm1-m, miroc5 and gfdl-esm2m models reasonably simulated the mean annual rainfall at shebe, sodo, jimma, hosaina, sokoru and woliso stations respectively. the implication of finding was that, any model dataset requires proper evaluation an interpretation before use as a decision tool for water resource management and planning at local level. it was also found that, higher resolution data does not mean quality and representative but the model type and local microclimate also play great role. therefore, water resource experts, the country’s dam authorities, environmentalists or the climate modelers should evaluate climate model reliability before making use it. similarly, those who are working in gibe iii watershed can use the selected model dataset as a source of data for water resource management and modeling works at the watershed. since the data used for this study did not include seasonal evaluations of precipitation and temperature, future studies should focus on reliability study of nex-gddp dataset for the climate models on seasonal basis in this watershed. 6. acknowledgments the authors gratefully acknowledge national meteorological agency of ethiopia for provision of observed data. similarly, climate analytics group and nasa ames research center for preparing official website (https://dataserver.nccs.nasa.gov/thredds/catalog/bypa ss/nex-gddp/bcsd/catalog.html) for downloading nasa nex-gddp dataset distributed by the nasa center for climate simulation (nccs). 7. references achilleos, g.a. 2011. the inverse distance weighted 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dataset. number model country and institution 01 access1-0 1 commonwealth scientific and industrial research organization and bureau of meteorology, australia 02 canesm2 canadian centre for climate modelling and analysis, canada 03 cnrm-cm5 centre europeen de recherche et formation avanceesencalculscientifique, france 04 csiro-mk3-6-0 commonwealth scientific and industrial research organization queensland climate change centre of excellence, australia 05 gfdl-esm2m geophysical fluid dynamics laboratory, america 06 ipsl-cm5a-lr institute pierre-simon laplace, france 07 miroc5 atmosphere and ocean research institute, japan 08 mpi-esm-mr max planck institute for meteorology, germany 09 mri-cgcm3 max planck institute for meteorology, germany 10 noresm1-m norway consumer council, norway 11 bcc-cms1-1 beijing climate center, china 12 bnu-esm 3 institute of global change and earth system sciences, beijing normal university, china 13 ccsm4 national center for atmospheric research, america 14 cesm1-bgc national center for atmospheric research, america 15 gfdl-esm2g geophysical fluid dynamics laboratory, america 16 inmcm4 institute of numerical calculation, russia 17 ipsl-cm5a-mr institut pierre-simon laplace, france 18 miroc-esm atmosphere and ocean research institute, japan miroc-esm 19 chem atmosphere and ocean research institute, japan 20 mpi-esm-lr max planck institute for meteorology, germany 21 gfdl-cm3 geophysical fluid dynamics laboratory, america abiy et al. evaluating the of reliability of nasa nex-gddp dataset 153 appendix table 2. performance metrics (rmse, rsq and nse) analysis for two models. rmse mean monthly rainfall month observed canesm2 rmse* csiro-mk3-6-0 rmse* 1 34.6 25.2 9.4 20.75 19.3 15.3 20.5 2 14.0 34.4 –20.4 29.9 –15.8 3 74.5 67.5 7.0 80.7 –6.2 4 124.0 96.5 27.4 91.3 32.6 5 147.0 131.9 15.1 156.9 –9.9 6 196.0 203.8 –7.9 175.3 20.6 7 231.1 203.3 27.9 254.3 –23.2 8 190.3 214.8 –24.5 215.1 –24.8 9 163.6 196.2 –32.7 145.7 17.9 10 89.6 106.3 –16.7 120.3 –30.7 11 24.2 50.6 –26.4 20.9 3.3 12 18.0 30.3 –12.3 40.9 –22.9 rsq mean monthly rainfall month observed canesm2 rsq* csiro-mk3-6-0 rsq* 1 34.6 25.2 0.9 19.3 0.9 2 14.0 34.4 29.9 3 74.5 67.5 80.7 4 124.0 96.5 91.3 5 147.0 131.9 156.9 6 196.0 203.8 175.3 7 231.1 203.3 254.3 8 190.3 214.8 215.1 9 163.6 196.2 145.7 10 89.6 106.3 120.3 11 24.2 50.6 20.9 12 18.0 30.3 40.9 nse of climatological (long-term) men monthly rainfall observed canesm2 nse* csiro-mk3-6-0 nse* 1 34.6 25.2 88.9 0.948 19.3 233.7 0.949 2 14.0 34.4 416.5 29.9 250.6 3 74.5 67.5 49.3 80.7 38.5 4 124.0 96.5 753.1 91.3 1066.0 5 147.0 131.9 228.1 156.9 97.2 6 196.0 203.8 62.1 175.3 425.2 7 231.1 203.3 775.8 254.3 536.3 8 190.3 214.8 601.8 215.1 614.3 9 163.6 196.2 1066.2 145.7 319.0 10 89.6 106.3 278.5 120.3 941.0 11 24.2 50.6 694.6 20.9 11.1 12 18.0 30.3 151.4 40.9 524.8 note: *calculated based on equation. abiy et al. east african journal of sciences volume 16(2): 133-154 154 appendix table 3. climatological mean annual precipitation (1976-2005) for each model and observation data for each station. models meteorological stations sokoru atnago hosaina jimma nekemte shebe sodo woliso canesm2 1360.9 1386.6 1152.2 1466.7 1488.8 1546.2 1143.6 1348.3 csiro-mk3-6-0 1350.6 1359.7 1119.8 1446.0 1516.9 1516.7 1054.3 1295.0 miroc5 1300.7 1406.1 1151.1 1502.0 1487.0 1559.3 1209.7 1384.4 ipsl-cm5a-lr 1446.7 1385.0 1187.2 1521.0 1464.7 1600.8 1191.1 1284.3 gfdl-esm2m 1213.6 1350.2 1174.2 1506.8 1461.6 1587.8 1167.6 1231.8 noresm1-m 1345.9 1399.5 1215.9 1590.8 1521.9 1680.3 1180.3 1287.3 mpi-esm-mr 1366.6 1335.4 1115.7 1478.0 1499.3 1567.0 1075.2 1285.8 mri-cgcm3 1381.2 1388.5 1198.8 1513.8 1541.8 1593.0 1161.9 1335.4 access1-0 1392.0 1403.3 1132.3 1504.5 1523.4 1591.3 1130.0 1316.3 cnrm-cm5 1364.2 1367.6 1143.4 1455.8 1437.5 1511.6 1176.0 1308.9 observed 1306.9 1722.1 1231.5 1481.9 1972.9 1527.5 1302.9 1236.5 east african journal of sciences (2018) volume 12 (1) 1-10 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: abdiahmed120@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) characterization of soil of jijiga plain in the somali regional state of ethiopia abdi ahmed1*, nigussie dechassa2, setegn gebeyehu3, and yibekal alemayehu2 1ethiopian somalis pastoral and agro-pastoral research institute, p.o. box 398, jijiga, ethiopia 2haramaya university, school of plant sciences, p. o. box 138, dire dawa, ethiopia 3 sustainable impact platform, international rice research institute, dar es salaam, tanzania abstract: low soil fertility and poor soil fertility management practices constrain crop production in ethiopia. diagnosing soil fertility problems and characterizing soils are a prerequisite for formulating appropriate soil fertility management practices. however, most soil fertility problems in ethiopia are not diagnosed, and the soils are not characterized. this invariably leads to lack of documented information for judicious application of soil ameliorative measures to increase crop yields. this study was, therefore, aimed at characterizing soil of jijiga plain in the somali regional state of ethiopia on which wheat is commonly grown. the study was conducted during the main cropping season of 2012/2013. the study area was stratified in to three altitude categories 1650 1700, 1750 1800, 1850 1900 meters above sea level prior to sampling. then, a total of 3 x 2 x 30 x 3 = 540 disturbed soil samples were collected from the surface (0-15 cm) and subsurface (15-30 cm) layers across the altitude categories. the samples were composited treatment-wise to 3 x 6 = 18 sub-samples. the composite soil sub-samples were analyzed for selected soil physico-chemical properties. the data were analyzed using descriptive statistics. the results indicated that both the surface and subsurface soils are clayey in texture. the ph of the soil at the layer of 0 30 cm ranged from 8.37 to 8.82 and is rated as strongly alkaline. the exchangeable ca2+ contents of the soil at the surface and subsurface soil layers were 24.52 and 30.52 cmol+/kg, respectively, which is rated as very high in both soil layers; the exchangeable mg2+ content is 7.36 cmol+/kg in the surface soil layer, which is rated as high, but 10.21 cmol+/kg in the sub-surface soil layers, which is rated as very high. the exchangeable na+ content of the soil ranges from 0.33 to 2.16 cmol+/kg, which is rated as medium to high. the exchangeable k+ contents of the surface and subsurface soil layers are 1.1 and 1.4 cmol+/kg, respectively, which are rated as high and very high in the surface and sub-surface soil layers. the cation exchange capacity of the soil ranges from 37.17 to 40.49 cmol+/kg, which is rated as high to very high. the percent base saturation in the surface soil is 89.63% whereas that in the sub-surface soil is 109.23%, which is rated as very high. the contents of soil organic carbon (1.81%) and total nitrogen (0.13%) in the surface soil layer were found to be medium whereas those of the sub-surface soil layer were found to be low. however, the available phosphorus contents of both the surface (2.4 mg kg-1 soil) and sub-surface (1.87 mg kg-1 soil) soil layers were found to be very low. it could, thus, be concluded that, the soil of the study area is characterized by strong alkalinity with high contents soluble calcium carbonate, very low content of plant-available phosphorus, and medium contents of soil organic matter as well as total nitrogen. however, the texture and other chemical properties of the soil do not appear to limit crop production. therefore, there is a need to take ameliorative measures aimed at lowering the ph and increasing availability of soil phosphorus, soil organic carbon, and total nitrogen to improve wheat and other crop yields in the study area. keywords: available phosphorus; cation exchange capacity; soil organic carbon; soil organic matter; soil texture; soil ph 1. introduction agriculture is the mainstay of the national economy of ethiopia, contributing over 90% of export, 85% of employment and 55% of gdp; the country has great potential for agricultural development with a total area of 113 million ha, of which 65% is estimated to be arable (getinet et al., 2001). despite the fact that agriculture plays an important role in the economy of the country, it is characterized by low technology and low productivity (getinet et al., 2001), as a result of which the country suffers from food insecurity (mishra et al., 2004). this is a paradox, which would invite researchers to investigate the causes of the problem and suggest feasible solutions. in addition, agriculture plays a great role in the growth of ethiopia’s economy and will command the lead in importance for many years to come (rosell and olvmo, 2014). therefore, the country’s development efforts must focus primarily on improving the sector (mishra et al., 2004). among the major causes for low agricultural productivity is the intensive exploitation of the agricultural resources by anthropogenic activities, which has put tremendous mailto:abdiahmed120@gmail.com abdi et al. east african journal of sciences volume 12 (1) 1-10 2 pressure on the country’s natural resources in general and the soil in particular (wakene, 2001). the country’s agriculture can be improved by developing appropriate national land management strategies. however, to suggest appropriate land management options to protect the soil for appropriate utilization requires sound information on its characteristics and dynamics (mohammed, 2003). therefore, so far and to date, efforts have been made by a number of researchers and governmental institutions to identify soil related problems and suggest remedies for further development of the agricultural sector (mohammed, 2003). the drylands of ethiopia consist of a wide range of agro-ecologies including the arid, semi arid, and dry sub-humid and cover about 75% of the total land mass, whereas the lowland dryland areas in ethiopia, cover about 55% of the land mass of the country (moard, 2000). the dryland areas are inhabited by about one third of the ethiopian population, and are the major source of its livelihood (kidane et al., 2003). however, similar to other agricultural ecologies, crop productivity is very low, and crop yields are principally limited by the low and highly variable rainfall amounts, both between and within seasons. in addition, crop production is limited by the progressive decline in soil fertility, as the farming practices do not adequately restore nutrients (fao, 2010). generally, in ethiopia, information on present soil fertility status is not adequate to meet the requirement of agricultural development programs as a result of which rational fertilizer recommendations based on actual limiting nutrients of a soil for a given crop are lacking (ifpri, 2010). besides, the productivity of some soils is constrained by some inherent limiting factors even though they have high potential productivity or are naturally fertile (gebreyes et al., 2008). therefore, the main problem in formulating appropriate intervention packages to address prevalent productivity constraints in any ecosystem is the lack of baseline data on land productivity, and identified soil-related constraints in the selected areas (muya et al., 2011). thus, knowledge and understanding gained from characterizing soils of a certain agro-ecosystem would be essential for managing land, and this information could also help in formulating soil improvement strategies locally, nationally, and regionally (debela et al., 2011). the agro-pastoralist farmers in jijiga plain in the ethiopian somali regional state are producing cereal crops particularly wheat, which is the principal staple grain and ranks second to sorghum in terms of area and volume of production (csa, 2013). however, in this area, compared to other wheat growing agroecologies in the country, the productivity of the crop is very low with an average grain yield of 1.0 ton ha-1on farmers’ fields (somali region lncdb, 2015 annual report). this yield is much lower than the national average yield of 2.11 ton ha-1 (csa, 2013). in general, the low average yield of the crop is primarily due to depleted soil fertility, low fertilizer usage, and lack of access to other improved crop management inputs (asnakew et al., 1991). in many parts of ethiopia, there is an increasing demand for information on soils as a means to produce food. this is because, to improve the productivity of a crop in the study area, there is a need to develop appropriate intervention packages to address soil problems that constrain crop growth and development. for this, documented information about the physicochemical properties of the soil is required. however, the physico-chemical properties of soil of jijiga plain, which constrain crop production, have not yet been studied and documented well. this study was, therefore, conducted to diagnose and elucidate selected physico-chemical properties of soil of jijiga plain on which wheat is being grown and identify soil fertility problems that constrain production of the crop. 2. materials and methods 2.1. description of the study area the jijiga plain is located in the northern part of the somali regional state of ethiopia. it covers 40,861 km2, of which the rangelands extend over 36,629 km2. it is bordered in the east by the republic of somalia, in the west by the oromia regional state, and in the south by ogaden lowlands (fig 1). the plain is a low lying, vast area, and most of its landmas is located in fafen zone, previously jijiga zone, excluding gursum and babile districts. however, at micro-level, the physiographic feature is a rolling type of landmass, which forms a number of drainage channels that facilitate runoff towards the jerer and wabishebele river basins. the climate is arid and semi-arid influenced by the gulf of aden and the indian ocean to the north and east and by the highlands of ethiopia lying in northwest of the region. the jijiga plain is characterized by having a bimodal type of rainfall with an average annual precipitation of less than 200 mm in the southeast to some 600 700 mm in areas of the north and western parts of the plain. however, the onset of the two rainfalls varies between areas within the jijiga plain. the northern and northwestern parts of the plain are characterized by having two cropping seasons, the first rainy season comes as the ‘dira’ rain which commences during mid-march and extends to the end of may and the second rainy season comes as ‘karan’ rain which starts during the mid of july and ends in late september. in this part of the plain, the ‘karan’ rain is normally heavier than the ‘dira’ rain. both sets of rain are equally important for cultivation and maturation of crops. however, the southern part of the plain which includes some peripheral areas of the ogaden lowlands also have two rainy seasons which are ‘dira’ in which the rain starts during mid of march and stretches towards the end of may and ‘deyr’ in which the rain starts in early october and ends at the end of november. the texture of the soils in most areas is almost clayey, except some exposed soils with steep slope gradients, which are sandy or gravely. abdi et al. characterization of soil of jijiga plain 3 figure 1. map of the study area. 2.2 sampling methodology and description of soil sample collection sites a stratified sampling method was employed for sample collection through priory placement of sampling points into the relevant groups or strata. the delineation of sampling units or landscape based on altitude range was done before going to the field and was greatly facilitated by the use of google earth software and global positioning system (gps) receiver. therefore, based on altitude category (landscape), the study area was classified into three sampling units. the first sampling unit was delineated as a landmass in altitude category of 1,650 -1,700 meters above sea level, which includes areas starting from jijiga town (9022’00.32”n and 42048’07.81”e) extending east towards the catchment areas of elbahaye dam (9024’08.52”n and 42051’09.69”e). the second sampling unit was delineated as a landmass in the altitude category of 1,750-1,800 meters above sea level, which includes areas extending from horefedi village (9036’25.53”n and 42058’56.11”e) north towards lafe isa (9020’05.47”n and 43002’22.90”e). the third sampling sub-section of the field was delineated as a landmass in altitude range between 1,850-1,900 meters above sea level, and this includes an area which extends from east of mekenis (9034’57.58”n and 42048’02.09”e) and stretches towards the northeast of heregel (9029’55.63”n and 42043’52.64”e) (fig 1). a random selection of points were chosen to withdraw samples within each stratum to collect soil samples from the sampling depths of 0 15 cm and 15 30 cm which are considered as surface and subsurface soils, respectively. however, in each of the sampling units, the sampling points were selected by using a zigzag sampling pattern. in addition, sample collection across the altitudinal category at each depth was done manually and typically by using an auger. then about 30 soil samples were collected from each altitude range across each sampling depth. sampling from each altitude range across the sampling depths was replicated three times. therefore, a total of 3 x 2 x 30 x 3 = 540 disturbed soil samples were collected. the samples collected were composited treatment-wise to 3 x 6 = 18 representative composite soil samples. finally, the composite soil samples were subjected to laboratory analysis for selected soil physical and chemical properties. 2.3. sample preparation and laboratory analysis the representative composite soil samples collected from the wheat growing areas in jijiga plain were airdried and ground to pass through a 2 mm size sieve in preparation for analysis of selected soil properties. for the analysis of soil total n, the soil samples were further passed through a 0.5 mm sieve. finally, the composite soil samples were analyzed for selected agriculturally relevant soil physico-chemical properties at the soil laboratory of ethiopian somali pastoral and agro-pastoral research institute, following standard analytical procedures. 2.4. analysis of soil physical properties the soil physical property determined in the laboratory was soil texture (percent sand, silt and clay). determination of particle size distribution was carried out by the hydrometer method as described by okalebo et al. (2002). once the sand, silt, and clay were separated, the soil in each sub-sections of the field was categorized based on landscape and assigned to a textural class based on the soil textural triangle described by rowell (1994). 2.5. analysis of soil chemical properties similarly, the disturbed composite soil samples of each location were subjected to laboratory analysis to determine chemical properties: ph(1:2.5), exchangeable cations (cmol+/kg ) (ca2+, mg2+, na+, k+), cation exchange capacity (cec)(cmol+/kg ), electrical conductivity (ec)(ds/m), caco3 content (%), soil abdi et al. east african journal of sciences volume 12 (1) 1-10 4 organic carbon content (oc)(%), total nitrogen content (tn)(%), available phosphorous content (mg p kg-1 soil) and sodium adsorption ratio (sar)(%). soil ph was determined as described by carter (1993) using a ph meter with combined glass electrode in water (h2o) at 1:2.5 soil: water ratio. electrical conductivity was measured as described by okalebo et al. (2002) by using a conductivity meter on saturated soil paste extracts obtained by applying suction. calcium carbonate content of the soil was estimated by acid neutralization method in which the soil carbonate was decomposed by excess standard hcl solution and back titrated with standard naoh after filtering. from the amount of acid (hcl) required to neutralize the carbonate, the caco3 equivalent was estimated as described by sahlemedhin and taye (2000). to determine organic carbon content of the soils, the walkley and black (1934) method was employed in which the carbon was oxidized under standard conditions with potassium dichromate in a sulfuric acid solution. also the total nitrogen content of the soils were determined as described by sahlemedhin and taye (2000) using the kjeldahl procedure by oxidizing the organic matter with sulfuric acid and converting the nitrogen into nh4+ as ammonium sulfate. determination of available phosphorous was carried out by the olsen method using sodium bicarbonate (0.5m nahco3) as an extraction solution as described by olsen et al. (1954). the contents of basic exchangeable cations (ca2+, mg2+, na+, k+) (cmol+/kg) in soils were measured using the atomic absorption spectrophotometer (hesse, 1972). the cation exchange capacity (cec) was determined by the ammonium acetate method as described by chapman (1965). sodium adsorption ratio was determined based on the results obtained from the analysis of the major cations ca, mg and na (in mmol l–1) of the aqueous extracts and calculated as described by richards et al. (1954). finally, the percent base saturation (pbs) was computed as the percentage of the sum of the exchangeable bases to the cec of the soil as: 2.6. data analysis the data obtained from the laboratory analysis of the physico-chemical properties of the soil were subjected to descriptive statistics using mstat statistical software package. 3. results and discussion 3.1. particle size distribution averaged across three types of landscape, the results of the study revealed variations in sand, silt and clay proportion between surface and sub-surface soils (table 1). the proportions of sand and silt decreased with increase in the sampling depth, but the clay proportion increased with the increase in sampling depth. therefore, the proportions of sand and silt are higher in the surface soil layers than in the sub-surface soil. however, the clay proportion is higher in the subsurface soil layers. the removal and easy transport of sand and silt from steep slopes by wind and water erosion processes and deposition of these materials on surface soils of flat lands might have caused the variation observed in the proportion of sand, silt, and clay between the surface and sub-surface soil layers. in agreement with the results of the present study, debela et al. (2011) concluded that slope differences and exposure to wind and water erosion caused variations in sand and silt proportions between soils of low lying and high lying areas. however, the increase in clay proportion in the sub-surface (15-30 cm) soils, compared to the surface (0-15 cm) soils, might be due to the nature of the parent material (limestone), coupled with variation in soil forming factors. consistent with this suggestion, mohamed and mishra (2007) reported that the soil of jijiga plain was developed mainly from limestone parent materials in association with granite or sandstone as well as basalt and this may have contributed to the clayey texture of the soils. according to the rating of hazalton and murphy (2007), the average proportion of sand and silt both in the surface and sub-surface soil layers are rated as low whereas the proportion of clay in both soil layers are rated as very high (table 1). the very high clay proportion may be important as it describes the stability in soil aggregates, which exhibits less liability of the surface soil layers to wind and water erosion. the very high clay content may indicate better water and nutrient holding capacity of the soils of the study area. therefore, this characteristic of the soil of the study area indicates high potential for crop production provided that other limitations are removed. table 1. soil particle size distribution on surface (0-15 cm) and sub-surface (15 30 cm) soils of jijiga plain. variable mean range st. dev 0 -15 cm 15 30 cm 0 -15 cm 15 30 cm 0 15cm 15 30 cm sand (%) 20.28 17.28 16.28 23.28 17.28 17.28 3.61 0.000 silt (%) 20.89 10.56 15.56 26.56 3.56 14.56 5.51 6.08 clay (%) 58.86 68.83 50.16 68.26 68.16 69.16 9.07 0.577 3.2. chemical properties 3.2.1. soil reaction (ph) averaged across the three altitudinal categories, the results of the study revealed consistent variations in soil ph between the surface and sub-surface soil layers of the study area (table 2). the average ph values of the surface and sub-surface soil layers across the three landscapes indicated that the ph value in the subabdi et al. characterization of soil of jijiga plain 5 surface soil layer is higher than that of the surface soil layer. the higher soil ph values of the subsurface soil layers could be attributed to high values of exchangeable ca2+ in the subsurface soil layer as compared to the surface soil layer which can be from weathered carbonaceous (limestone) parent materials from which the soil in the study area originated. the current result is in agreement with the findings of abayneh et al. (2006) who concluded that the increase in the ph of the soils of jijiga plain across sampling depth could be due to some leaching of carbonates from surface horizons and the carbonaceous substratum. therefore, according to the classification of soil reaction by tekalign (1991), the soils of the study area are strongly alkaline at both the surface (0-15 cm) and the sub-surface layers (15-30 cm depth) (table 2). soil reaction is a very important property for crop production since it determines the availability of nutrients, microbial activity, and physical condition of the soil (gupta, 2000). although the ph tolerance limits of different plants vary greatly, a neutral range, with ph values (in a 1:2.5 soil: water suspension) between about 6.3 and 7.5 is most suitable for most crops (landon, 1991). on the other hand, fageria et al. (2009) indicates that the optimum soil ph for the growth of most crop plants in the tropical soils is determined by crop species; however, a ph value of about 6.5 determined in water is adequate for the growth of most crop species. optimum ph range for wheat is 5.5 to 7.0 (hazelton and murphy, 2007). however, the observed average range of ph values (in a 1:2.5 soil: water suspension), both in the surface and sub-surface soil layers across the three altitudinal categories in the study area are far beyond this optimum ranges (table 2). therefore, both the surface and sub-surface soil layers in the study area limit productivity of wheat and most other crops. in agreement with this suggestion, slattery et al. (1999) concluded that on soils with a ph range of 7.5 to 8.5, crop growth can be limited because this range of ph significantly affects plant growth, primarily as a result of reduced availability of essential elements such as phosphorus, and most of the micronutrients, cu, fe, mn, mo, and zn. this suggestion is substantiated by mekuria et al. (2007) who reported that alkaline soils were less productive for wheat than soils within neutral ph range. 3.2.2. exchangeable cations and cation exchange capacity (cec) similarly, averaged across the three altitudinal categories, contents of exchangeable cations (ca2+, mg2+, na+ and k+) and the cation exchange capacity (cmolc (+) kg-1) of the soil of the study area varied between the surface and sub-surface soil layers (table 2). exchangeable ca2+ followed by mg2+ is the predominant cation in the exchange sites of both the surface and sub-surface soil layers. on the other hand, the exchangeable cations and the cec increased with soil depth in exactly the same pattern as observed in soil ph. this shows that the soil parent material primarily releases divalent cations. relatively high contents of ca2+ and mg2+ in surface and sub-surface soil layers were earlier reported for soils of jijiga agricultural research station by abayneh et al. (2006) and for soils of jelo micro-catchment by mohammed et al. (2005). the increase in exchangeable cation content and cation exchange capacity in the sub-surface soil layer could be attributed to possible upward movement of exchangeable bases from the sub-soil stratum to the sub-surface soil layers, which might have been derived from inherited carbonate rich parent materials (limestone). in agreement with this suggestion, debela et al. (2011) reported values of the similar magnitude for exchangeable bases in sub-surface soils semi-arid lowlands of eastern shoa, central ethiopia, and postulated that the limestone nature of the parent materials from which the soils were formed may have contributed to the increase in the exchangeable cations in the sub-surface soils. consistent with the above suggestion, curi and franzmeier (1987) concluded that a soil weathered from an alkaline parent material can experience upward transfer of bases. in agreement with the results of the present study, abayneh et al. (2006) reported increased cation exchange capacity in the subsurface soil layers of jijiga agricultural research station, which could be attributed to increased concentration of exchangeable bases. according to the rating of fao (2006), the contents of ca2+ in surface and sub-surface soil layers are rated as very high, respectively, whereas the contents of mg2+ is rated as high in the surface soil layers and very high in the sub-surface soil layers (table 2). similarly, according to the same rating, the na+ content in the surface soil layer is rated as high whereas it is rated as very high in the sub-surface soil layer. also the contents of exchangeable k+ in the surface and subsurface soil layers are rated as high and very high, respectively (table 2). the content of ca2+ in the soil of jijiga plain is in excess of adequate level required for crop production (table 2). this suggestion is evidenced by fageria et al. (2008) who reported that for tropical soils, an adequate level of exchangeable ca2+ for optimum growth of most crop plants in the range of only 2 to 3 (cmol+/kg). similarly, the level of mg2+ in the soil of jijiga plain was found to be beyond the optimum range (table 2). in agreement with this suggestion, fageria et al. (1997) reported that the content of mg2+ adequate for optimum plant growth varied from soil to soil, plant species to plant species, and even among cultivars within species. however, mg2+ content in the range of 1.0 to 2.0 (cmol+/kg) is sufficient to produce maximum economic yield of field crops (fageria, 2002). according to the rating of fao (2006), the content of exchangeable potassium in both the surface and subsurface soil layers is high to very high (table 2), which means the nutrient is sufficiently available in the soil and its status would not limit crop growth and abdi et al. east african journal of sciences volume 12 (1) 1-10 6 development. according to the same rating, the content of exchangeable sodium in the surface soil is low whereas that in the sub-surface soil is very high, which is above 2.0 (cmol+/kg soil) (table 2). this means that salinity or the possibility crop plant injury due to sodium salts could be ruled out in the short term, but in the long run, there may be potential for salinity especially if precipitation reduces and droughts recur. therefore, it is important to take precautionary measures against possible build up of soluble salts in the soil of the study area. on the other hand, according to hazelton and murphy (2007), the cec of the surface and subsurface soil layers could be rated as high and very high, respectively (table 2). this means that the soil is resistant to changes in the soil chemical composition that are caused by land use systems (hazelton and murphy, 2007). 3.2.3. calcium carbonate content, sodium adsorption ratio (sar), electrical conductivity (ece) and percent base saturation (pbs) averaged across the three altitudinal categories, the results have revealed consistent variations in caco3 content (%) and sodium adsorption ratio (sar) (%) between the surface (0-15 cm) and subsurface (15-30 cm) soil layers of the study area (table 2). the average values of these soil chemical properties consistently increased across the sampling depths, and the parameters were higher in the sub-surface soils than in the surface soil layers. the possible reason for the increase in the calcium carbonate content of the subsurface soils as compared to that of the surface soils could be due to increased upward translocation of calcium from the subsoil horizon which may be attributed to the nature of the parent materials (limestone) from which the soils of the study area evidently originated. in agreement with this suggestion, mohamed and mishra (2007) concluded that the soils of most areas of jijiga plain are developed on mixed types of rock species dominated by limestone (secondary/ precipitates). on the other hand, regarding the rating of calcium carbonate generally, there are no precise ratings for contents of free carbonates, but values of over 40% can be considered as extremely calcareous (avery, 1964). however, according to the rating of fao (1990), a soil horizon having a caco3 content of > 15% within 100 cm from the soil surface qualifies for a calcic horizon and such a high carbonate content affects both the physical and the chemical properties of soils. hence, in the current study, the level of caco3 is ˃ 15% and it showed an increasing trend with increasing depth but these depths are considered as a plow depth and rooting zone for most small cereal crops including wheat. therefore, this problem could seriously affect crop production in the study area. this suggestion is in agreement with the calcium carbonate rating given by carter (1981) that 11 to 30% total carbonate as the critical levels that adversely affect crop growth. therefore, the calcium carbonate content of the soil of jijga plain is so high that it can seriously affect the production of wheat and other crops (table 2). table 2. chemical properties of surface (0-15 cm) and subsurface (15-30 cm) soils of jijiga plain. variable mean range st. dev 0-15 cm 15-30 cm 0-15 cm 15-30 cm 0 15 cm 15-30cm ph water (1:2.5) 8.37 8.82 8.338.41 8.71-8.88 0.039 0.095 ex. ca2+( cmol+/kg) 24.52 30.46 23.02-26.34 30.09-31.10 1.683 0.554 ex. mg2+( cmol+/kg) 7.36 10.21 6.897.63 8.72-11.10 0.410 1.296 ex. na+( cmol+/kg) 0.33 2.16 0.210.40 1.23-3.09 0.108 0.930 ex. k+( cmol+/kg) 1.1 1.4 1.011.17 1.1701.65 0.081 0.253 cec (cmol+/kg) 37.17 40.49 36.538.33 40.4740.5 1.011 0.017 ec (ds/m) 1.01 1.41 0.801.120 1.2041.79 0.185 0.334 caco3 (%) 16.05 18.66 15.9416.2 18.5918.7 0.133 0.064 organic carbon (%) 1.81 1.48 1.052.46 1.331.73 0.712 0.218 total nitrogen (%) 0.13 0.09 0.12-0.134 0.060.12 0.007 0.029 available p (mg kg-1) 2.36 1.87 1.762.74 1.282.4 0.525 0.557 sar 5.67 7.33 4.08.0 6.09.0 2.08 1.528 pbs 89.63 109.23 66.01-107 98.23-127.6 14.19 9.56 note: ex. = exchangeable with regard to the sodium adsorption ratio (sar), it is higher in the sub-surface soil layer than in the surface soil layer, which is consistent with the increase in the content of soluble na+ because the sar increased with soil depth in exactly the same pattern as observed in exchangeable na+ (table 2). however, averaged across the three landscapes, the mean sar values of both soil layers are below the critical sar value of 13% of the us salinity laboratory staff (1954) and soils in both layers are not sodic and this adverse soil chemical property (sodicity) may not be a limiting factor for wheat production in the study area (table 2). similarly, averaged across the three landscapes, the electrical conductivity (ece) of the soil increased with abdi et al. characterization of soil of jijiga plain 7 increase in the sampling depths, and the mean ece value is higher in the sub-surface soil layer than in the surface soil layer (table 2). the increase in the subsurface soil layer may be ascribed to increased entry of soluble exchangeable cations to the sub-surface soil layer through upward capillary movement with water from the subsoil stratum originating from the weathering of the limestone parent material. in agreement with this suggestion, curi and franzmeier (1987) reported that a soil weathered from an alkaline parent material can experience a large transfer of bases. the accumulation of soluble salts in the soil profile curtails crop growth by increasing the osmotic potential of the soil solution and inducing specific ion toxicity or nutrient imbalances (carter, 1993). these salts contain the cations na+, ca2+, and mg2+ and the anions cl-, so42-, hco3-, and co32which can be weathered from minerals and accumulate in the soil solution in areas where precipitation is too low to provide leaching (havlin et al., 1997). this is common particularly in arid and semi-arid regions like jijiga plain. the electrical conductivity (ece) measurement identifies soils which are potentially saline (okalebo et al., 2002). however, the mean ece values observed in both layers are not beyond the critical ece value of 4 ds m-1of the us salinity laboratory staff (1954) and soils in both layers are non-saline and may not be a limiting factor for wheat production in the study area for now. in agreement with the result of the current study, bernstein (1995) indicated that the ece value which ranges from 0 to 2 ds m-1 has crop response which is negligible. averaged across the three landscapes, the percent base saturation (pbs) of the soil increased with increase in sampling depth, and the mean pbs value is higher in the sub-surface soil layers as compared to the surface soil layer and the increase showed a similar trend to that of the exchangeable cations (table 2). therefore, the increased mean value in the subsurface soil may be ascribed to increased soluble exchangeable cations especially ca2+ and mg2+ at the sub-surface soil layer. in agreement with this suggestion, gebreyes (2008) also reported increased percent base saturation with increased sampling depth for soils of enewari, northeastern ethiopia. according to hazalton and murphy (2007) the percent base saturation of soils of jijiga plain is rated as very high. similarly, as suggested by landon (1991) soils having greater than 60% base saturation are rated as fertile soil. 3.2.4. organic carbon and total nitrogen in contrast to other chemical properties of the surface and sub-surface soil layers whose values increased with increase in the sampling depths, the organic carbon and total nitrogen contents of the soils consistently decreased with the increase in sampling depths (table 2). the decrease in organic carbon content of the soil across the sampling depths could be attributed to relatively higher organic matter content of the surface soil layers as a result of residual root debris, deposition from wind and water erosions, high biological activity and soil conditions suitable for decomposition of organic matter in the surface soil layer as compared to sub-surface soils. in agreement with the results of this study, prasad and power, (1997) indicated that nitrogen content in the sub-surface layer of any soil is generally less than that in the surface layer since most organic residues are deposited on the soil surface. according to the rating given by tekalign (1991), the organic carbon content in the surface soil layer is medium whereas that in the sub-surface soil layer is low. the total n content decreased across the soil layers in exactly the same pattern as the soil organic carbon content, suggesting a strong correlation between the contents of the two soil parameters. this suggestion is consistent with that of murage et al. (2000) who reported that soil organic matter is the best surrogate of soil quality and mineralized nitrogen supply for improved crop production. according to the rating of murphy (1968), the total nitrogen content of the surface soil layer is medium whereas that in the subsurface soil layer is low. these values indicate only moderate potential of the soil to supply n to plants through mineralization as well as organic carbon as a source of energy for soil biota for enhanced soil water and nutrient holding capacity. therefore, there is a need to provide external supply of nitrogen and organic carbon through application of mineral and organic fertilizers to enhance crop production in the study area. the medium soil organic carbon and high total nitrogen contents of the surface soil layers in the study area could be attributed to the relatively customary practice of returning crop residues back to the soils by the farming communities. thus, in the study area, almost all of the wheat growing farmers are using combine harvesters to harvest the crop and the chopped straw is returned to the soil on the spot. the decomposing is a source for soil biota, which in turn may increase the labile n in the soil through mineralization (prasad and power, 1997). the result of the present study is consistent with that of abayneh et al. (2006) who reported medium total n content of about 0.14% in the surface layers of soils of jijiga agricultural research station. 3.2.5. available soil phosphorus the data revealed variations in the amount of available phosphorus between the surface and the sub-surface soils of the study area. the amount of plant available p in the surface soil layers was higher than that in the subsurface soil layers (table 2). however, the available amounts of the nutrient in both surface and subsurface soil layers are low based on rating shown by cottenie (1980). the results are corroborated by abayneh et al. (2006) who reported a decrease in the contents of available p with increase in the sampling soil depth. the low content of available phosphorus could be attributed to sorption and its precipitation by calcium and magnesium bicarbonates. in agreement with the results of this study, mengel et al. (2001) state abdi et al. east african journal of sciences volume 12 (1) 1-10 8 that the very low available phosphorus contents may be ascribed to high soil calcium contents, which lead to precipitation of phosphorus as ca phosphates. on the other hand, tekalign and haque (1991) reported that 8 mg p kg-1 soil was the critical level of p for ethiopian soils when assessed by the olsen method. except for the extreme layer, the content of available p showed a decreasing trend with soil depth. this is in agreement with the findings of tekalign amd haque (1988) who reported that topsoil p is usually greater than that in subsoil due to sorption of the added p, greater biological activity, and accumulation of organic material on the surface. mulugeta (2000) also indicated decrease in p content with depth due to fixation by clay and precipitation by ca, which were found to increase with depth. similarly, mohammed et al. (2005) observed low levels of available p in the surface horizons of the cultivated soils of the chercher highlands in eastern ethiopia. therefore, low contents of available p is a common characteristic of most soils in ethiopia (tekalign and haque, 1991; yihenew, 2002; wakene and heluf, 2003). thus, it can be deduced that the very low amount of available p in soils is the most important factor constraining wheat production in soils of jijiga plain. this suggestion is in agreement with that of page (1992), who stated that less than 4 mg plantavailable p per kg soil indicates p-deficiency. this result is corroborated by holford and cullis (1985) who reported that lactate extractable p (mg p kg-1 soil), from a soil at the depth of 0–10 cm which is ˂ 5 mg p kg1soil is very low for wheat production. similarly, fageria et al. (2009), suggested that soil p content below 12 mg kg-1 soil, is not optimum for plant growth and responses are likely to occur to the addition of the nutrients fertilizer. generally, in the study area, texture, ph, exchangeable cations, cations exchange capacity, electrical conductivity, calcium carbonate, and sodium adsorption ratios increased with increase in soil depth. however, the organic carbon, total nitrogen content, and available phosphorus contents decreased with increase in soil depth. the decrease could be attributed to the decline in soil organic matter content with increase in soil depth since these soil parameters are essential components of the former (mohamed and mishra, 2007). 4. conclusions this study has demonstrated that the soils of the study area are clayey in texture. the laboratory tests have also indicated that these soils contain a lot of soluble calcium carbonate which is responsible for the very high ph values (8.37 to 8.82) of the soil and its strong alkalinity. however, the soils are currently non-saline and non-sodic. the contents of soil organic carbon and total nitrogen are medium, which are moderately conducive for plant growth and development. the contents of exchangeable potassium, magnesium, calcium as well as the cec of the soil were also found to be optimum for crop production. however, plantavailable p content of the soil was found to be very low, which is attributable to the presence of high amounts of soluble calcium carbonates that react with the nutrient and renders it insoluble through precipitation. the strongly alkaline soil reaction and the very low content of available soil phosphorus are the major factors that constraint production of wheat and other crops in the study area. thus, the soil of jijiga plain requires ameliorative measures to reduce its ph and increase availability of phosphorus. furthermore, the soil also needs improving its status of soil organic carbon and total nitrogen. therefore, farmers need to use both mineral and organic fertilizers to mitigate the effect of high soil ph and enhance the availability of soil phosphorus, total nitrogen, and organic carbon for optimum crop growth and sustainably increased yields. future research needs to focus on elucidating the effect of integrated soil fertility and water management options, formulation of site and crop specific fertilizer recommendations, and selection of crop species or varieties that are adapted to the low-p soil for enhancing production of wheat and other crops in the study area. 5. references abayneh esayas, ashenafi ali, gebeyahu belay and tibabu chekol. 2006. soil of jijiga agricultural research center. the federal democratic republic of ethiopia, ethiopian institute of agricultural research, national soil research center(nsrc) soil survey and land evaluation section. isricworld soil information, a icsu world data center for soils. soil.isric@wur.nl. asnakew woldeab, tekaligne mamo, mengesha bekele and tefera ajamo. 1991. soil fertility management studies on wheat in ethiopia. pp.137-172. in: hailu gebre mariam, tanner, d. g. and mengistu huluka (eds.). wheat research in ethiopia: a historical perspective. addis abeba. iar/cimmyt. avery, b. w. 1964. the soils and land use of the district around aylesbury and hemel and hempstead. mem soil survey. hmso, london. bernstein, l. 1975. effects of salinity and sodicity on plant growth. annual review phytopathology, 13: 295312. carter, m. r. 1993. soil sampling and methods of analysis. canadian soil science society. lewis publishers, boca raton, florida. 823p. carter, m. r. 1981. association of total caco3 and active caco3 with growth of fine tree species on chernozemic soils. canadian j. soil sci., 61: 173-175. chapman, h. d. 1965. cation exchange capacity. pp. 891-901. in: black, c. a., evans, d. d., ensminger, j. l. and clark, f. e. 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(eds.) soil analysis: an interpretation manual, csiro publishing, collingwood, australia. pp. 103–128. rosell s. and olvmo m. 2014. an analysis of soil productivity parameters and livelihoods in west shewa and south wollo, ethiopia, scottish geographical journal, 130 (1): 51-66. tekalign mamo and haque, i. 1991. phosphorus status of some ethiopian soils, ii. forms and distribution of inorganic phosphates and their relation to available phosphorus. tropical agriculture, 68: 1: 2-8. tekalign mamo and haque, i. 1988. phosphorus status of some ethiopian soils. east african agricultural and forestry journal 53 (3): 123-130. tekalign tadese. 1991. soil, plant, water, fertilizer, animal manure and compost analysis. working document no. 13. international livestock research center for africa, addis ababa. us (united states) salinity laboratory staff. 1954. diagnosis and improvement of saline and alkali soils. united states department of agriculture, handbook no. 60. 160p. wakene negassa and heluf gebrekidan.2003.forms of phosphorus and status of available micronutrients under different land-use systems of alfisols in bako area of ethiopia. ethiopian journal of natural resources, 5(1): 17-37. wakene negassa chewaka. 2001. assessment of important physicochemical properties of dystric udalf (dystric nitosols) under different management systems in bako area, western ethiopia. an m. sc. thesis presented to school of graduate studies of alemaya university. 93p. walkley, a. j. and black, i. a. 1934. estimation of soil organic carbon by the chromic acid titration method. soil science ,37: 29-38. yihenew gebreselassie. 2002. selected chemical and physical characteristics of soils of adet research centre and its testing sites in northwestern ethiopia. ethiopian journal of natural resources, 4 (2): 199-215. east african journal of sciences (2018) volume 12 (1) 41-50 _____________________________________________________________ licensed under a creative commons *corresponding author. e-mail: vwioko@yahoo.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) comparing effects of copper and chromium treatments on growth of cyperus esculentus l. in field and in vitro studies and further explanation by restriction fragment length polymorphism analysis vwioko e. d.* and digwe k. c. department of plant biotechnology, faculty of life sciences, university of benin, benin city, nigeria. abstract: the contamination of agricultural soils by heavy metals following long-term use of fertilisers, urbanisation and industrialisation raise concerns. the effects of copper (cuso4) and chromium (cr2o3) salt solutions on cyperus esculentus tubers and plants were studied under in vitro and potted-field conditions. the objective of the study was to evaluate the effects of copper and chromium ions on the growth of cyperus esculentus. the concentrations of copper and chromium salt solutions prepared and applied as treatments were 0 ppm, 100 ppm, 200 ppm, 300 ppm, and 400 ppm. in vitro study was set up using petri dishes. parameters measured were percent germination, number of plumules and radicles, plumule and radicle lengths. in the field study, percent germination, plant height, fresh and dry weights were measured. the in vitro and field experiments were laid out as a completely randomised design with four replications. germination in the in vitro study was observed in copper and chromium treated tubers 3 and 6 days after treatment (dat) respectively. multiple radicle and plumule formation per tuber was recorded and this was observed to be metal concentration-dependent. results of the field experiment showed that tubers germinated in both copper and chromium treated soils 5 and 7 days after planting, respectively. copper solutions stimulated plant height as compared to control whereas chromium concentrations greater than 100 ppm inhibited plant height. these differences were significant (α = 0.05). the micrograph from the rflp analysis revealed alterations of dna bands obtained for 400 ppm cu-treated and all (except 100 ppm) cr-treated plants as compared to dna bands of control plants. it is concluded that copper inhibited cyperus esculentus at 400 ppm only whereas concentrations above 100 ppm chromium affected the plant negatively. keywords: copper; chromium; treatments; rflp; cyperus esculentus 1. introduction cyperus esculentus l. of the family cyperaceace is an erect, grass-like perennial plant. it is one of the underutilised or “orphan” crops with enormous benefits to man especially the edible tubers. this plant is cosmopolitan and its cultivation can be hampered by the degradation of arable lands by heavy metal pollution. cyperus esculentus (also called tiger nut) is popular because of its nut-like tubers eaten raw by many residents of benin city, nigeria. it is cultivated in many northern states of nigeria where the use of fertilizers and pesticides for crop cultivation is common and are strongly championed by farmers and governments. fertilizers and pesticides contain traces of heavy metals. the presence of heavy metals in soil is significant because they are non-degradable and can persist for a long time (iwegbue et al., 2013). detection of moderate to high concentrations of heavy metals in soil will make that environment unsuitable for agricultural purpose. there is a risk associated with high soil concentration of toxic metals to plants, natural waters and humans (adriano, 2001). in nigeria, the pace of urbanisation, industrialisation and other various anthropogenic pressures have introduced high contamination incidences by heavy metals in several cities (ladigbolu and balogun, 2011; nubi et al., 2011). contamination of soils by heavy metal is dependent on their bioavailability as well as their mobility in the environment. heavy metals are absorbed by plants when grown in polluted sites and when consumed deliver these heavy metals into the human body (zurera-cosano et al., 1989; cambra et al., 1999). the presence of heavy metals in many agricultural farming regions has been heightened by yearly widespread flooding incidents of localities that are under pressure from unconventional mining of solid natural minerals and deposits in many communities of the northern states of nigeria. reports of pollution by heavy metals in nigeria have suggested chromium and copper (azumi and bichi, 2010; garba et al., 2010; ibeto and okoye, 2010) to be widespread. soil concentrations of heavy metals range from less than 1 mg/kg to 100,000 mg/kg, either due to geologic origin or anthropogenic activity of the soil (iwegbue et al., 2013). soil contents of heavy metals can be viewed as a double edged sword because of the role of some in normal plant growth and living organisms to the toxicity associated with presence of others (pb, cd and hg etc). copper and chromium are amongst the most commonly occurring heavy metal pollutants and major constituents of industrial effluents (thilakar et al., mailto:vwioko@yahoo.com vwioko and digwe east african journal of sciences volume 12 (1) 41-50 42 2012). both copper and chromium are essential trace elements required for the normal functioning of human physiology whereas only copper remains essential as a micronutrient in plants. chromium is not required by plants though it is constantly present in the soil. these metals are toxic and deleterious at higher concentrations to both plants and animals, and the essential ones are beneficial at lower concentrations. their absence in humans also causes deficiency condition like decreased fertility and abnormal bone formation for chromium and copper, respectively (ayodele and ajala, 2009). deficiency or excess copper in plants causes anomaly by altering important physiological process like photosynthetic electron transport. copper is a structural component of proteins and enzymes that participate in vital growth processes. copper concentrations exceeding 20µg/g can be toxic (wright and welbourn, 2002). the presence of excess copper during germination and growth reduces seed germination and inhibits growth by interfering with cellular processes like respiration and photosynthesis (prasad and strazalka, 1999), as well as pigment content, development of plant organelles, protein synthesis, biomass, root, leaf and stem growth. due to nutrient-metal interaction, the pattern of nutrient uptake is disturbed when high concentration of chromium is present in the soil. the phytotoxicity of chromium includes root growth reduction, seed germination inhibition, depressed biomass, necrosis and chlorosis. chromium stress in plants has been demonstrated to cause damage to dna, pigments, protein and also initiates lipid peroxidation. chromium toxicity reduces seed germination and radicle growth. inhibition of growth in plants during chromium stress results from cell division inhibition and induction of chromosomal aberrations (zeid, 2001). excess copper, chromium and cobalt produced adverse effects on biomass, iron concentration, chlorophyll a and b contents, protein, and catalase enzyme activity in cauliflower (chatterjee and chatterjee, 2000). the exposure of living organisms to heavy metals at high concentrations creates oxidative stress that generates toxic oxygen species such as hydrogen peroxide (h2o2), hydroxyl radical (oh*) and superoxide radical (o2-) (de vos et al.,1993). toxic oxygen species cause changes in membrane lipids, proteins and nucleic acids. dna damages such as nitrogen base degradation, singleand double-strand breakage and cross-linkage to proteins are induced by toxic oxygen species (imlay and linn, 1986). assessment of the toxic effects of heavy metals in living organisms is one most commonly studied subjects in environmental science. dna finger printing techniques like rapd and aflp have clearly shown dna alterations in animals, bacteria and plants induced by pollutants. the application of molecular techniques in metal toxicity studies were reported by korpe and aras (2011), mengoni et al. (2000), de wolf et al. (2004) and liu et al. (2009). these molecular techniques were engaged because of their sensitivity. the toxicity of individual elements to a plant species will be better understood when data on population (growth) parameters are supported by results of molecular analysis. this will give correct interpretations of the effects of individual elements on the plant species. copper was selected as one metal essential for normal growth of plants and chromium as non-essential element but ubiquitous in the soil. there is dearth of information on the use of cyperus esculentus in heavy metal studies. plant responses to in vitro and field-based metal treatments differ. there is gain in knowledge if such information is provided by empirical studies. the objective of this study was to evaluate effects of copper and chromium ions on growth of c. esculentus, supported by data from restriction fragment length polymorphism (rflp) analysis. 2. materials and methods 2.1 plant material and preparation of copper and chromium solutions healthy looking tubers of cyperus esculentus l. were obtained from northern farmers using “hausa quarters” along sokpomba road, benin city, as base with latitude of 6.32893o n and longitude of 5.62803oe. the test of viability was carried out using the floatation method by gently putting the tubers in a bowl containing deionised water for 3-5 minutes. tubers that sank down were taken as viable and used for the experiment. analytical grade salts of cuso4 and cr2o3 were purchased and used for the preparation of copper and chromium solutions. the concentrations applied were 0, 100, 200, 300, and 400 ppm. these were based on ecological screening values of metals. preparation was done by dissolving the appropriate weight of the salts required to prepare any particular concentration in one litre of deionised water. 2.2. in vitro experimental setup forty cleaned petri-dishes were fitted with filter papers (whatman no.1) and correctly labelled according to the salt solutions (treatments) to be applied. five millimetres of treatment solutions were used to wet the filter paper. ten (10) viable tubers were put into each petri dish. thereafter, another five millilitres solution was added to the petri dishes. each petri-dish was augmented with an appropriate solution when the need arose. each treatment was replicated four times. this set up was monitored for germination, radicle and plumule production daily. 2.3. field experimentation top loamy soil (0-15 cm depth) was collected as a composite sample from a fallow space in the botanic garden, department of plant biology and biotechnology, university of benin, benin city, nigeria. forty experimental pots were prepared by filling 3 kg soil into each and correctly labelled according to the specific treatments in the study. the experimental pots were perforated underneath. these pots were watered vwioko and digwe comparing the effects of copper and chromium on growth of cyperus esculentus l. 43 with the respective treatment solution and left in the field overnight. sowing was done the following day in the morning. five tubers were sown per experimental pot at 2-3 cm depth into the soil. each pot was watered with 200 ml of the respective treatment solution immediately after sowing. this volume was below water holding capacity of soil and sufficient to make the soil sample wet for the metal ions to be in contact with the plant root. each treatment was replicated four times. the subsequent application of copper and chromium treatment solutions to the soil was done every fourth day for nine weeks after planting. field data collected were percent germination, plant height, fresh and dry weights. germination record was taken daily for 18 days after planting. plant height measurements (during vegetative stage of growth) were taken using a measuring tape. nine weeks after of planting (9 wap), the plants were harvested from the soil along with roots. the roots were washed to remove all soil particles from the root region. the plants were air-dried and their fresh weights recorded. then each plant was correctly labelled and taken to the oven for drying at the temperature of 50oc for a period of 4-5 days to obtain the dry weight. the plant samples were measured continually until a constant dry weight was obtained. 2.4. molecular analysis of plants three weeks after sowing, leaf samples of plants from each concentration were collected and used for molecular analysis. dna extraction was carried out using kit. 2.4.1. dna extraction one gramme (1g) fresh leaf samples were obtained for dna extraction and analysis. dna was isolated using dna extraction kit (norgen biotek, canada) as directed by the manufacturer (okoror et al., 2015). 2.4.2. restriction fragment length polymorphism analysis the reaction mixture for the rflp analysis was prepared by adding 5µl of assay buffer, 10µl of bsa and 3µl of restriction enzyme (hind i) to 10µl of the dna extract. for 1 hour at 37oc, the vials were incubated to completely digest the dna. the silver stain of polyacrylamide gel was used to visualize the products digested by the restriction enzyme. then, 50 ml of a fixing solution diluted with 9.5 ml ethanol and 30.5 ml double distilled water were used for gel fixation for 30 minutes and for another 30 minutes impregnated with silver staining solution. the gels were then washed for 1-3 minutes in double-distilled water. after the staining solution was removed, for 10 minutes, the gels were kept in the developing solution in the dark, such that the developing solution was poured out when the bands were dark enough and immediately, the stopping and preserving solution was added to stop and preserve the patterns formed (parani et al., 1997; sahu et al., 2012). 2.5. percent phytotoxicity and metal tolerance index phytotoxicity percentage and metal tolerance index were calculated on days 3 and 9 for cu ion treatments and on days 20 and 35 for cr ion treatments in the in vitro experiment using the formula by bauddh and singh (2011). (1) (2) 2.6. statistical analysis mean and standard deviation were calculated for the data recorded in the study. two-factor analysis of variance was used to analyze the data obtained. separation of means was carried out using duncan multiple range test or tukey’s test with the aid of gen stat version 8. 3. results the results obtained in this study are shown in tables 16, figures 1-8 and plate 1. 3.1. germination germination was recorded for cyperus esculentus tubers both in the laboratory and field experiments. the percent germination records showed that c. esculentus tubers germinated in all concentrations of cu2+ solution applied as treatments during the in vitro experiment. delay in germination was very pronounced in 300 and 400 ppm cu treated tubers where the first indication of germination occurred 9 and 12 days after treatment (dat) respectively (table 1). the least percent germination was recorded in 400 ppm cu2+ treatment. for chromium (cr3+) solution treated tubers, germination was observed 6 and 20 days after treatment in 100 ppm cr3+ and 400 ppm cr3+, with a mean percent germination of 12.5% and 5% respectively. further delay in germination was observed in 200 ppm cr3+ and 300 ppm cr3+ treated tubers (table 2). the viability test of tubers carried out prior to the setting up of in vitro experiment did not prove their quality and is suspected to be responsible for the low germination observed in control treatments. germination in the field was entirely different from what was obtained in the laboratory. five days after planting (5 dap) in the field, germination was recorded in all treatments except for 300 ppm cr3+and 400 ppm cr3+. there was improvement by 7 dap where germination was observed in all treatments. the application of the cu2+ and cr3+ solutions to the soil did not affect germination of c. esculentus tubers significantly when compared to values obtained for control and treated 18 dap (table 3). generally, the range of vwioko and digwe east african journal of sciences volume 12 (1) 41-50 44 germination in the field was 65-97%. this indicated that the tubers were viable and showed resistance to metal treatments applied in soil. table 1. percentage germination of cyperus esculentus tubers treated with cuso4 solution during in vitro experiment. cu2+ solution(ppm) 3 dat 6 dat 9 dat 12 dat 15 dat 18 dat 0 15.50±7.50 32.50±25.00 35.00±23.80 35.00±23.80 37.50±22.17 40.00±21.60 100 7.55±5.17 15.50±5.57 17.32±7.50 17.32±7.50 20.62±7.58 27.50±7.08 200 7.55±5.17 11.57±5.57 11.57±5.57 14.14±4.14 14.14±4.14 18.93±5.90 300 0.00±0.00 0.00±0.00 9.50±2.50 14.14±4.14 14.14±4.14 15.60±5.12 400 0.00±0.00 0.00±0.00 0.00±0.0 15.50±5.16 15.50±5.16 15.50±5.16 note: values = mean ± s.d; dat = days after treatment; ppm = parts per million. table 2. percentage germination of cyperus esculentus tubers treated with cr2o3 solution during in vitro experiment. cr3+ solution (ppm) 6 dat 20 dat 25 dat 30 dat 35 dat 100 12.50±5.00 12.50±5.00 12.50±5.00 15.50±2.50 15.50±2.50 200 0.00±0.00 0.00±0.00 12.50±5.00 12.50±5.00 12.50±5.00 300 0.00±0.00 0.00±0.00 0.00±0.00 12.50±5.00 15.00±5.77 400 0.00±0.00 5.00±1.77 11.50±5.57 11.50±5.57 11.50±5.57 note: values= mean ± s.d; dat= days after treatment; ppm= parts per million table 3. percentage germination of cyperus esculentus tubers in soil treated with cuso4 and cr2o3 solutions. treatments conc.( ppm) 5 dap 7 dap 9 dap 11 dap 15 dap 18 dap control 0 18.10a±7.74 25.00a±11.09 50.00a±12.43 70.00a±34.64 92.50a± 5.00 92.50a± 5.00 cu2+ 100 20.00a±10.00 32.50a±5.00 45.00a±19.50 67.50a±25.94 70.00a±28.30 82.50a±14.03 200 20.00a±5.00 27.00a±8.28 57.50a±11.13 60.00a±22.43 65.00a±26.46 65.00b±26.46 300 22.50a±5.00 27.00a±4.14 42.50a±9.57 70.00a±21.60 77.50a±26.30 80.00a±18.28 400 25.00a±7.10 32.50a±9.62 82.50b±12.58 95.00a±10.00 95.00a±10.00 97.50a±2.00 cr3+ 100 17.50a±5.00 47.50a±12.17 77.50b±18.93 90.00a±8.16 92.50a±5.00 95.00a±5.77 200 15.00a±1.00 32.50a±5.00 57.50a±15.00 80.00a±14.14 90.00a±4.14 97.50a±2.00 300 0.00a±0.00 32.50a±8.93 47.50a±27.54 67.50a±22.17 77.50a±22.17 82.50a±13.63 400 0.00a±0.00 32.50a±5.00 47.50a±27.54 72.50a±26.30 75.00a±23.80 85.00a±13.80 note: dap = days after planting; ppm = parts per million, values are presented as mean ± s.d, means with similar alphabets as superscript in one column are not different significantly at 0.05 level of significance using tukey’s test. 2.3. number and length of plumules produced number of plumules produced was recorded only in the in vitro experiment. multiple plumule formation was observed in tubers of cyperus esculentus during the in vitro experiment. the mean number of plumules produced by the tubers in the control treatments was 6 obtained 18 dat applications. copper ion solutions depressed plumule production in cyperus esculentus tubers. numbers of plumules produced by cu2+-treated tubers were higher than that of cr3+ treated tubers. the negative effects of cu2+ solutions applied were observed at 300 ppm and 400 ppm concentrations. plumule production was not observed in 400 ppm cu2+ until 10 dat (figure 1). plumule production by cr3+ treated tubers was first observed in 100 ppm 6 dat. plumule production in cr3+ concentrations higher than 100 ppm were recorded at least 20 dat and average of 1 plumule/ tuber was observed. thirty-five dat, the average number plumule/tuber was 3, 2, 1 and 1 for 100, 200, 300 and 400 ppm cr3+-treated tubers respectively (figure 2). the observation of control treatments ended 18 dat and this wide disparity in time of response by tubers treated with cr3+ solutions made control plot not to fit into figure 2 appropriately. the average length of plumule recorded 18 dat for tubers in control treatments was 19 cm. other treatments gave lower values. for example, the average lengths of plumule recorded for 100, 200, 300 and 400 ppm cu2+ treated tubers were 9.7, 7.3, 5.4, and 2.8 cm respectively (figure 3). similarly, the average lengths of plumule recorded 35 dat for 100, 200, 300 and 400 ppm cr3+ treated tubers were 8.6, 2.1, 1.5 and 2.1 cm respectively (figure 4). the wide disparity in time between records taken for control and cr3+ treated tubers did not permit the addition of a plot for control. but the control can be read from figure 3. vwioko and digwe comparing the effects of copper and chromium on growth of cyperus esculentus l. 45 figure 1. number of plumules produced by cyperus esculentus tubers treated with cuso4 during in vitro experiment. (dat= days after treatment. error bars represent standard deviation). figure 2. number of plumules produced by cyperus esculentus tubers treated with cr2o3 during in vitro experiment. (dat= days after treatment. error bars represent standard deviation). figure 3. average length (cm) of plumule produced by cyperus esculentus tubers treated with cuso4 during in vitro experiment. (dat = days after treatment. error bars represent standard deviation). figure 4. average length (cm) of plumule produced by cyperus esculentus tubers treated with cr2o3 during in vitro experiment. (dat= days after treatment. error bars represent standard deviation). 3.3. number and length of radicles produced number of radicles per tuber was recorded only in the in vitro experiment. eighteen dat, the mean number of radicles in control treatment was 98. the numbers of radicles per tuber under cu2+treatments were 43, 27, 9 and 0 for 100, 200, 300 and 400 ppm respectively (figure 5). radicle production was inhibited at the highest cu2+ solution applied (400 ppm). radicle production in crtreated tubers began 20 dat. radicle initiation was recorded in 200 and 300 ppm cr3+ 23 dat. thirty-five dat, average numbers of radicles produced for cr treatments were 11, 5, 3 and 5 for 100, 200, 300 and 400 ppm respectively (figure 6). radicle length records taken showed that cu and cr treatments of c. esculentus tubers affected extension growth negatively. for example, 18 dat, mean radicle length for control, 100, 200, and 300 ppm cu2+-treatments were 15.70, 6.09, 2.87, and 1.30 cm respectively (figure 7). mean values of radicle length for 100, 200, 300 and 400 ppm cr-treated tubers were 2.35, 0.95, 0.80 and 1.96 cm respectively 35 dat (figure 8). the value for average radicle length of 400 ppm cr3+ treated tubers was higher than that obtained for either 200 or 300 ppm cr3+ treated tubers. this observation is not unconnected with viability of the tubers used in the in vitro experiment. figure 5. number of radicles produced by cyperus esculentus tubers treated with cuso4 during in vitro experiment. (dat = days after treatment. error bars represent standard deviation). 0 2 4 6 8 10 a v e ra g e n u m b e r o f p lu m u le s p e r tu b e r number of days after cu treatments 0 ppm cu 100 ppm cu 200 ppm cu 300ppm cu 400 ppm cu 0 0.5 1 1.5 2 2.5 3 3.5 a v er ag e n u m b er o f p lu m u le s p e r tu b e r number of days after cr treatments 100 ppm cr 200 ppm cr 300ppm cr 400 ppm cr 0 5 10 15 20 25 a v e ra g e l e n g th (c m ) o f p lu m u le p e r tu b e r number of days after cu treatments 0 ppm cu 100 ppm cu 200 ppm cu 300ppm cu 400 ppm cu 0 2 4 6 8 10 12 a v e ra g e l e n g th (c m ) o f p lu lm u le p e r tu b e r number of days after cr treatments 100 ppm cr 200 ppm cr 300ppm cr 400 ppm cr 0 50 100 150 a v er ag e n u m b er o f ra d ic le s p e r tu b e r number of days after cu treatments 0 ppm cu 100 ppm cu 200 ppm cu 300ppm cu 400 ppm cu vwioko and digwe east african journal of sciences volume 12 (1) 41-50 46 figure 6. number of radicles produced by cyperus esculentus tubers treated with cr2o3 during in vitro experiment. (dat = days after treatment. error bars represent standard deviation). figure 7. average length (cm) of radicles produced by cyperus esculentus tubers treated with cuso4 during in vitro experiment. (dat= days after treatment. error bars represent standard deviation). figure 8. average length (cm) of radicles produced by cyperus esculentus tubers treated with cr2o3 during in vitro experiment. (dat = days after treatment. error bars represent standard deviation 3.4. restriction fragment length polymorphism micrograph the result obtained for the rlfp analysis shows dna bands obtained from plant samples grown in crand cu treated soils (plate 1). eight dna bands were indicated in the micrograph. comparing the bands formed using the band obtained from 0ppm treated plants as standard; the effects of the different treatments were visible. three out of eight bands clearly show distortions. these were dna bands 5, 7 and 8 obtained from plant samples treated with 400ppm cu, 400ppm cr and 200ppm cr respectively. plate 1. a micrograph showing the dna bands obtained from a rflp analysis of cyperus esculentus treated with different concentrations of cuso4 and cr2o3 solutions. note: 1= cr 100 ppm, 2 = cu 200ppm, 3 = cu 300ppm, 4 = cu 100ppm, 5 = cu 400ppm, 6= 0ppm, 7 = cr 400ppm, 8= cr 200ppm, the last was completely digested and came up with no band. 3.5. plant heights, fresh and dry weights progressive increase in height of cyperus esculentus plants grown in cu2+ and cr3+ treated soils was observed from 3 wap to 9wap (table 4). after 9 weeks of growth, mean height of plants recorded in control,100, 200, 300 and 400 ppm cu2+ treated soils were 69.03, 66.00, 71.00, 79.70, and 80.60 cm respectively. from the values observed, cu2+ treatments applied supported increase in plant height. plant height values recorded in soils treated with 100, 200, 300 and 400 ppm cr3+ solutions were 85.10, 59.63, 60.73, and 44.03 cm respectively 9wap. comparing these values to that of control, one observes enhancement of plant height in 100 ppm cr3+ treated soils and depression in plant height in 200 400 ppm cr3+ treated soils (table 4). fresh and dry weight values obtained in the study are shown in table 5. the average values for fresh weight (fw) of plants grown in control, 100, 200, 300, and 400 ppm cu2+ treated soils were 2.14, 2.89, 1.22, 2.04 and 1.41 g respectively. fresh weight for 100, 200, 300 and 400 ppm cr3+ treated plants were 1.22, 1.59, 1.20 and 1.57 g respectively. the differences in fresh weights were significant (α= 0.05). the mean fw of plants grown in 100 ppm cu2+ treated soils was higher than that of the control (0 ppm) while mean fw for 100 ppm cr3+ was lower than control. dry weights (dw) of plants obtained for control, 100, 200, 300 and 400 ppm cu2+ treated soils were 0.72, 0.80, 0.52, 0.69, and 0.61 g respectively. also, 100, 200, 300 and 400 ppm cr3+ treated plants gave 0.61, 0.53, 0.46, and 0.57 g respectively as dw. the mean dw of control plants was lower than that for 100 ppm cu2+ plants but higher than that obtained for 100 ppm cr3+ treated plants (table 5). 3.6. phytotoxicity and metal tolerance indices the estimates of phytotoxicity and metal tolerance indices during the in vitro experiment are shown in table 6. the phytotoxic effects estimated at 3 dat and 9 dat for tubers treated with 100 ppm cu2+ solutions were 37.14 and 65.81% respectively. this indicates that 0 5 10 15 a v er ag e n u m b er o f ra d ic le s p e r tu b e r number of days after cr treatments 100 ppm cr 200 ppm cr 300ppm cr 400 ppm cr 0 5 10 15 20 3 d a t 6 d a t 9 d a t 1 2 d a t 1 5 d a t 1 8 d a t a v er ag e le n g th (c m ) o f ra d ic le p e r tu b e r number of days after cu treatments 0 ppm cu 100 ppm cu 200 ppm cu 300ppm cu 400 ppm cu 0 1 2 3 4 20 dat 25 dat 30 dat 35 dat a v er ag e le n g th (c m ) o f ra d ic le p e r tu b e r number of days after cr treatments 100 ppm cr 200 ppm cr 300ppm cr 400 ppm cr 1 2 3 4 5 6 7 8 vwioko and digwe comparing the effects of copper and chromium on growth of cyperus esculentus l. 47 the toxic effects were more pronounced 9 dat than at 3 dat as compared to control. the longer the exposure time, the weaker the average resistance induced by the tubers. the phytotoxic effects estimates for 300 and 400 ppm cu2+ treated tubers were 100%. the estimates showed that the resistance induced by tubers in these treatments did not produce measurable responses. the estimates of phytotoxic effects for tubers treated 100 ppm cr3+ 20 dat and 35 dat were 42.86 and 64.29% respectively. the higher estimate showed that the effects became more pronounced at 35 dat when compared with the control. higher estimated phytotoxic values at 35 dat were obtained for 200 ppm cr3+ and 300 ppm cr 3+. the phytotoxic estimates at 20 dat for 200, 300 and 400 ppm cr 3+ were the same, i.e. 100%, and this represents total inhibition with no measurable response. the phytotoxic effects estimates should be interpreted as a gap between control and metal treated tubers. the estimated metal tolerance indices for 100 ppm cu2+ at 3and 9 dat were 62.86 and 34.14%. similarly, values estimated for 200ppm cu2+ were 17.14 and 27.36%. these infer the ability of the plant to tolerate the concentrations of metals applied as treatments. the higher values of metal tolerance indices show that the tubers at such concentrations exhibited some level of tolerance. for 100 ppm cr3+ treated tubers, metal tolerance indices at 20 and 35 dat were 57.14 and 35.71% respectively; while for 200 ppm cr3+ treated tubers at 20 and 35 dat were 0 and 14.44% respectively. a value of zero (0) indicates metal intolerance. the tubers were suspected to build up some level of tolerance for the metal as the exposure periods increased from 20 35 dat for treatments > 200 ppm cr3+. table 4. plant heights of cyperus esculentus grown in different concentrations of cuso4 and cr2o3 solutions treated soils. treatments conc.(ppm) 3 wap 5 wap 7 wap 9 wap control 0 41.00a±1.77 68.40a,b±13.25 69.73a,b,c±10.89 69.03a,b±11.58 cu2+ 100 44.00a±4.19 68.03a,b±2.55 67.17a,b,c±2.97 66.00a,b±0.70 200 42.33a±1.53 64.30a,b±6.73 68.03a,b,c±3.65 71.00a±1.95 300 38.97a±1.01 69.10a,b±11.65 74.60a,b±6.36 79.70a±10.64 400 33.57a,b±9.02 66.70a,b±9.40 79.80a,b±12.76 80.60a±12.97 cr3+ 100 43.37a±3.98 77.43a±11.25 83.87a±13.98 85.10a±13.33 200 36.03a,b±2.35 66.57a,b±5.77 56.73b,c±9.71 59.63a,b±12.72 300 35.47a,b±2.84 69.70a,b±14.92 55.57b,c±7.40 60.73a,b±7.41 400 23.77a,b±5.78 39.03b±15.92 43.37c±9.60 44.03b±9.90 note: wap= weeks after planting, values are presented as mean± s.d, mean with similar alphabets as superscript in one column are not different significantly at 0.05 level of significance using tukey’s test. table 5. fresh and dry weights of cyperus esculentus plants harvested from the different concentrations of cuso4 and cr2o3 solution treated soils 9 weeks after planting (wap). t re at m e n ts c o n c .( p p m ) fresh weight (g) dry weight (g) control 0 2.1418a,b±0.1362 0.7167a±0.0784 cu2+ 100 2.8933a±1.0625 0.7954a±0.3881 200 1.2191b±0.4785 0.5175a±0.2451 300 2.0439a,b±1.2987 0.6896a±0.3429 400 1.4074b±0.3853 0.6102a±0.2388 cr3+ 100 1.2169b±0.3952 0.6102a±0.1511 200 1.5937b±0.2535 0.5321a±0.1195 300 1.2026b±0.5441 0.4600a±0.1429 400 1.5658b±0.7364 0.5734a±0.2005 note: data are presented as mean± s.d, mean with similar alphabets as superscript in one column are not different significantly at 0.05 level of significance using duncan multiple range test. table 6. estimates of phytotoxicity and metal tolerance index of copper and chromium treatments on cyperus esculentus tubers during the in vitro experiment. metal concentration dat phytotoxicity (%) metal tolerance index (%) 100 ppm cu 3 37.14 62.86 100 ppm cu 9 65.81 34.19 200 ppm cu 3 82.86 17.14 200 ppm cu 9 72.64 27.36 300 ppm cu 3 100.00 0.00 300 ppm cu 9 100.00 0.00 400 ppm cu 3 100.00 0.00 400 ppm cu 9 100.00 0.00 100 ppm cr 20 42.86 57.14 100 ppm cr 35 64.29 35.71 200 ppm cr 20 100.00 0.00 200 ppm cr 35 85.56 14.44 300 ppm cr 20 100.00 0.00 300 ppm cr 35 87.84 12.16 400 ppm cr 20 100.00 0.00 400 ppm cr 35 70.21 29.79 vwioko and digwe east african journal of sciences volume 12 (1) 41-50 48 4. discussion damages to growth and development like photosynthesis, lipid metabolism and nucleic acid synthesis in plants following exposure to high metal concentration are subject of ecotoxicological studies. these toxic effects of heavy metals can be shown with population and molecular parameters. in this study, high concentration of cu and cr ions affected cyperus esculentus negatively. the in vitro study revealed the direct effect of cu and cr on cyperus esculentus plants. germination percent obtained indicated inhibitory effects where cr-treated tubers were more inhibited. the delay associated with germination of plants was very prominent in cr-treated tubers. for example, 200 ppm, 300 ppm, and 400 ppm treated tubers germinated twenty days after treatment (20 dat). by 12 dat, germination has been recorded in similar copper concentrations. the field experiment gave a different insight into germination of c. esculentus in cu and cr-treated soils. germination records show that the plant germinated in all concentrations of cutreated and cr-treated soils within 5 and 7 days after treatment respectively. the delays in germination were obviously shorter with growth in the soil. this suggests that the effect of treatments on plants were weakened by the presence of soil particles. morealso, the mean percent germination records did not show any significant differences in the effects of increasing metal concentrations in the soil. the direct contact of tubers with the treatment solutions in vitro was probably the “actual” effect of the treatments. singh et al (2007) reported the inhibitory effects of cu treatments on seed germination and seedling growth of wheat. ashagre et al. (2013) reported that heavy metals affect seed germination by their ionic toxicity which caused decrease in the breakdown of starch by amylase and concomitant weak germination response recorded. hema and subramani (2013) reported decrease in germination of vigna radiata following copper and chromium treatments. there is also the existence of genetic variability among crop species and cultivars for ionic stress. plumule and radicle production by crop species subjected to metal treatments is used to assess the species response and tolerance. in this study, multiple plumule formation was recorded in tubers of cyperus esculentus. plumule production was observed in all concentrations of copper treatments, with 300 ppm cu and 400 ppm cu solutions producing delayed response of over ten days after treatments. longer delayed response of plumule production of over 23 dat was observed in 200 ppm, 300 ppm and 400 ppm cr-treated tubers. the number and length of plumules produced were inhibited when the values of cu-treated and cr-treated tubers are compared with control. cutreated tubers exhibited the feature of multiple plumule formation whereas this feature was recorded in 100 ppm cr and 400 ppm cr-treated tubers only 35 dat. other treatments; 200 ppm and 300 ppm cr-treated tubers produced only one plumule each. multiple plumule development is a plant habit shown by species to survive threat from herbivores and stressful conditions. this habit gives c. esculentus advantage to compete with weeds during cultivation. number and length of radicles produced by cu-treated tubers decreased as the concentrations increased, 18 dat. tubers treated with 400 ppm cu failed to produce radicle. ashagre et al. (2013) reported that tomato seeds (lycopersicon esculentum cultivar roma vf) did not produce roots in 300, 400, 500 and 600 ppm cu treatments. akinci and akinci (2010) reported that radicle lengths of cucumis melo seeds were inhibited by chromium ion treatments. similarly, panda et al. (2002) stated that the inhibition of radicle growth of seeds by chromium ions varied with concentrations. in this study, length and number of radicles produced by c. esculentus tubers were less than 3 cm long and few in numbers. hayyat et al. (2015) stated that chromium ions inhibited root growth in many crops. the response of cyperus esculentus in metal-treated soil samples showed some interesting variations. mean plant heights obtained for 200 ppm, 300 ppm and 400 ppm cu-treatments were higher than control, indicating some level of stem growth stimulation nine weeks after planting (9 wap). the reason for this can be inferred from the application of treatments which was done every fourth day as against the all-time contact with the treatments during the in vitro experiments. we suggest that the space of days between one treatment application and the next gave the plants ample time to use the available copper ions in the soil for beneficial growth. hans et al. (2004) reported that chromium retards plant growth. mean plant height was inhibited by 200 ppm cr and above treatments in the soil, nine weeks after planting. these values were 86.4%, 88% and 63.8% of control value for 200 ppm, 300 ppm and 400 ppm cr-treated plants respectively. mean plant height recorded for plants grown in soil treated with 100 ppm cr was higher than the value for control plants. this value was 123% of the value for control. zeid (2001) stated that low concentrations of chromium as ionic treatments in plants, cause increase amylase activity, germination and growth. chromium as an element is not known to play a functional importance in plants. one is unable to explain the mechanism behind this increase in plant height (growth) recorded at 100 ppm cr-treatment of soil. fresh and dry weights records of whole plants showed that low concentrations of copper (100 ppm) facilitated the accumulation of matter. this is connected to the nutrient role played by copper at low concentrations. the roots of plants harvested from chromium treated soils showed some peculiar morphological features. the fibrous roots were coloured reddish or pinkish which were different from those of control or cu-treated plants. the roots formed conspicuous and dark rings at intervals along vwioko and digwe comparing the effects of copper and chromium on growth of cyperus esculentus l. 49 the length and from these points, other side roots that were thick and distinct were produced. this feature was not observed with control or cu-treated plants. the dna band patterns obtained after rflp analysis showed that the dna contents from plants grown in 0 ppm (control), 100 ppm cu, 200 ppm cu, 300 ppm cu and 100 ppm cr exhibited similar patterns with no issue of missing bands. this indicates that the dna structures were neither disrupted nor altered at these concentrations of cu and cr treatments. vinod et al. (2012) stated that heavy metal stress in plants causes inefficiency of dna synthesis. furthermore, they stated that high concentration of cu led to reduced synthesis of dna in wheat. heavy metals cause injury at the cellular level following the production of free radicals (panda and choudhury, 2005). dna extracts obtained from plants grown in 400 ppm cu, 200 ppm cr, 300 ppm cr and 400 ppm cr-treated soils showed pronounced alterations of the band patterns. the band patterns suggest that the dna structure and synthesis in the plants were affected by the treatments. the dna band patterns of plants treated with 300 ppm cr was not conspicuous and this suggests that the restriction enzyme (hind 1) applied may have cleaved it disproportionately, resulting in complete digestion and meaningless band pattern. choudhary and panda (2005) stated that the production of ros under chromium ion stress leads to dna and protein damage. it is possible to connect the growth responses of cyperus esculentus in crtreated soils with the micrograph showing the dna bands. from rflp result, chromium can be described as more inhibitory or toxic than copper. 5. conclusion generally, the effects of copper and chromium on germination, and growth of cyperus esculentus were majorly inhibitory and inhibition increases as the concentrations increased. the most damaging concentration of copper to germination and growth was at 400 ppm, whereas chromium was detrimental at concentrations above 100 ppm. the effects of copper and chromium were studied both morphologically and at the molecular level using rflp techniques. the toxicity observed in both cases show that chromium is more harmful to cyperus esculentus than copper. this study has empirically showed the differences in response of c. esculentus tubers in vitro and potted field conditions. it is clear that the response in vitro where the tubers were in direct contact with the metal solutions should be reckoned and interpreted as the sole and uninterfered effects of cu2+ and cr3+ metals. also, the cr3+ exhibited higher phytotoxic effects than cu2+ solutions as treatments. in the field, the roots of chromium treated plants were found to be reddish or pinkish coloured, which were peculiar to them. poor yields of crop plants grown in agricultural soils exposed to anthropogenic risks should be given critical investigation to gain sufficient understanding. in future, the effects of other heavy metals would be considered to ascertain the tolerable concentrations to the plant and highlight associated environmental risks. 6. references adriano, d. c. 2001. trace metals in terrestrial environment. biochemistry, bioavailability and risk of metals. springer-verlag, new york. akinci, i. e., and akinci, s. 2010. effect of chromium toxicity on germination and early seedling growth in melon (cucumis melo. l.). african journal of biotechnology, 9 (29): 4589-4594. ashagre, h., almaw, d. and feyisa, t. 2013. effects of copper and zinc on 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stress physiology and biochemistry, 8: 203-213. wright, d. a. and welbourn, p. 2002. environmental toxicology. cambridge university press, cambridge, united kingdom. yruela, i. 2005. copper in plants. brazilian j. plant physiology, 17:145-156. zeid, i. m. 2001. responses of phaseolus vulgaris to chromium and cobalt treatment. biologia plantarum, 44: 111-115. zurera-cosano, g., moreno-rojas, r., salmeron-egea, j. and lora, r. p. 1989. heavy metal uptake from greenhouse border soils for edible vegetables. j. science, food and agriculture, 49: 307-314. hydrochemistry of lake adele, ethiopia east african journal of sciences (2018) volume 12 (2) 101-110 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: haile.4.hiwot@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) diagnosing the suitability of lake water for domestic and agricultural uses: a case study in eastern ethiopia haile arefayne shishaye school of water resource and environmental engineering, institute of technology, haramaya university, p. o. box 138, dire dawa, ethiopia abstract: lake adele is one of the lakes giving incomparable economic benefits in eastern hararghe zone. it is being used for irrigation and water supply purposes, especially for animals. however, the lake water quality has not yet been analyzed even though it is traditionally believed that it has quality problems. this research was, thus, undertaken to evaluate the quality, identify the origin, and analyze the hydrochemical composition of the lake water. three water samples were collected from the lake by a grab sampling method. samples were analyzed for six physicochemical parameters (temperature, ec, tds, ta, ph, and turbidity), major cations and anions, minor anions and trace metals using standard procedures. the laboratory measurements were weighed against the local and global standards. the results of the analysis revealed that the lake water has exceedingly intolerable levels of certain physical and chemical parameters. the gw-chart software was also used to produce the piper diagram that can graphically show the origin and geochemical composition of the lake water, which revealed that the origin of the lake is deep groundwater with a major geochemical composition of sodium bicarbonate. it is concluded that the lake water has particularly excess turbidity and dangerous levels of nitrate (no3-1), nitrite (no2-), ammonia (nh3), and lead (pb) that would make it unsafe to use for drinking as well as excess levels of salinity, ph, and sodium adsorption ratio (sar) that would make it unfit to use for irrigation. keywords: domestic use; irrigation; lake adele; major ions; origin and geochemical composition; water quality 1. introduction water is the most important substance for human and other lives (ranjan, 2012; tiwari and ranga, 2012). chemically, pure-water, which contains atoms of various isotopes of hydrogen and oxygen, is recognized as a complex substance; i.e., water is not found in a chemically pure form. it contains other minerals in a solution form that conduct an electric current. moreover, the different uses of water also need other necessary chemicals to be found in water. drinking water, for example, should contain several electrolytes including ca, cl, f, mg, na, k which are very crucial for different functions in the human body (e.g., absorption and digestion functions) (who, 2011). the interaction of water with the landscape components during the process of the hydrologic cycle, the anthropogenic activities like agricultural practices and mining, and some other natural and manmade causes are the primary factors that affect the hydro-chemical composition of water (setegn, 2012). due to this fact, natural water is composed of complex groups of gases, minerals and organic substances, and suspended colloidal matters. it is, therefore, considered as a dynamic chemical system. thus, the need for water may either be associated with the quality or availability in different parts of the universe, especially in the developing countries (who, 2011). the process of water quality analysis is, therefore, very important for the assessment of current water quality in comparison with the universal standards, and prediction of future quality conditions of water bodies (usepa, 2012; who, 2011). in general, information on the physicochemical composition of water is very crucial to solving the problems associated with the different uses of water (shishaye and nagari, 2016; usepa, 2012; who, 2011). water quality analysis is usually conducted based on certain parameters according to the harmfulness index (liu et al., 2014). the quality standards of the different parameters in water used by different countries are known as one of the following: quality criteria, maximum allowable levels, maximum contaminant limits, and maximum contaminant standards (shishaye and nagari, 2016; liu et al., 2014; usepa, 2012). the concentration standards of the different parameters may vary from region to region and from country to country, even though their variations may be small (shishaye and nagari, 2016). for example, americans use the water quality standards designed by usepa; while, european countries use the european health based water quality standards (usepa, 2012; liu et al., 2014). however, most of the countries in africa use the drinking water quality standards designed by who, even though some countries use their own drinking water standards designed based on the who standards. accordingly, ethiopia has its own water quality standards called “ethiopian health based water quality standards” designed based on the who mailto:haile.4.hiwot@gmail.com haile arefayne east african journal of sciences volume 12 (2) 101-110 102 standards (emh, 2011). however, the quality of most of the groundwater and surface water resources in the country have not yet been measured and characterized well. in fact, tropical lakes are known to have very essential significances for regional economies and biodiversity conservations (branchu et al., 2010). some of the lakes in ethiopia are also giving similar benefits. however, their productivity, ecology, physicochemical characteristics and their water levels are being affected by different factors. some of the factors are climate change, overexploitation, geological processes, and some other limnological changes (liu et al., 2014; olana, 2014). the area/formation where the lake water comes from is also one of the factors affecting the quality of some lakes, e.g. lake beseka (shishaye, 2017). therefore, water quality analysis/characterization and comparisons with the national and international standards are very crucial to design effective and long lasting surface water management strategies and increase productive uses of water bodies. similarly, lake adele provides incomparable economic benefits for the nearby communities (belay, 2006). the nearby communities are using it as an irrigation water supply. furthermore, it is also under use for water supply purposes, especially for animals. however, because of quality problems, the lake water is not being used for drinking (belay, 2006). nevertheless, the levels of the contaminants and other hydrochemical parameters are not exactly known, for there has been no hydrochemical analysis conducted within the lake water so far, even though its quality problem can be easily detected with the naked eyes. the general objective of this research was, thus, to elucidate the physical properties and chemical compositions of lake adele water. more specifically, the research was aimed at identifying the hydro-geochemical composition and origin of the lake water, comparing the concentrations of the measured parameters with the local and universal standards, and determining the suitability of the lake water for different uses. 2. material and methods 2.1. description of the study area lake adele is located in eastern haraghe zone, oromia regional state, ethiopia. it has a length of about 3.2 kilometers and width of 1.15 km (measured from google earth). it is located at the latitude and longitude coordinates of 9.425833 and 41.950833, respectively. it is characterized by “woina-dega (subtropical)” agro-climatic zone that receives a mean annual rainfall of 775.9 mm. the monthly rainfall in the site is greater than 100 mm from april to september, except in june, which is 48.4 mm. the wettest month is august, with a mean rainfall of 151.9 mm. the daily temperature of the site varies from 10 oc 25 oc. lake adele is one of the wintering areas for aquatic palearctic wintering birds. different wintering birds are commonly seen in the shallow parts of the lake. lake adele could thus be suitable for bird watching, for it is larger than the other two lakes in the area, i.e., the now vanished lake haramaya and lake finkile (fig. 1). physiographically, the lake watershed as a whole is part of the harar plateau areas, which is the upper part of wabi shebele basin. three major stratigraphic units including the precambrian crystalline basement (mainly granite), mesozoic sedimentary rocks (sandstone and limestone) and quaternary sediments from old to young characterize it (kebede, 2013). the precambrian basement complex includes the high-grade metamorphic gneisses and migmatites, and the intrusive granites. figure 1. adele haramaya dry lakes catchment, modified from belay (2006) 2.2. laboratory measurements 2.2.1. glassware and instruments instruments like an electronic analytical balance with 0.001 sensitivity (afp, adam), polyethylene bottles, a mercury thermometer (0-100 0c), digital (ph, conductivity and temperature) meter (max electronics, india), volumetric pipettes (1, 5 and 10 ml), burette (50 ml), measuring cylinder (10, 25 and 50 ml), micropipette (0‒50 μl), borosilicate beakers (100, 250 ml), lab hot plate, volumetric flasks (50, 100, 250 and 1000 ml), whatman filter paper (no. 42), fume hood, serological water bath (bluefic), funnels, capped glass bottles (50 ml), flame atomic absorption spectrophotometer (210vgp, buck scientific), flame photometer (jenway), and uv-vis spectrophotometer were used during the laboratory measurements of the lake water chemistry. 2.2.2. chemicals and reagents hno3 (65‒68%, high-tech healthcare, india), h2so4 (98.0%, high-tech healthcare, india), hcl (35‒38%, hightech healthcare, india), prepared stock standard solutions (1000 ppm), disodium salt of edta (99.5%, bdh chemicals ltd poole england, ar), ebt (99.5%, fluka, switzerland), na2co3 anhydrous (99.9%, high-tech haile arefayne lake water suitability for domestic and agricultural purposes 103 healthcare, india), caco3 (99.5%, bdh chemicals ltd poole england, ar), agno3 (99%, high-tech healthcare, india), bacl2 (99%, fluka, switzerland), isopropyl alcohol (high-tech healthcare, india), na2so4 (high-tech healthcare, india), glycerol (high-tech healthcare, india) and distilled water were the chemicals and reagents used in this experiment. 2.2.3. cleaning of glassware and apparatus all the glassware and apparatus used in the entire analyses of all the parameters were washed with tap water and detergent, except in case of po43in which chromic acid was used. then, they were rinsed using distilled water and soaked with 10% (v/v) hno3 solution for 24 hrs. they were also rinsed with distilled water, and eventually airdried. the containers used for sampling were also rinsed with sample water prior to actual sample collection (apha, 1999). 2.2.4. water sampling, preservation and transportation representative water samples were collected by a grab sampling technique from the three different sampling sites within the lake (north, south, and eastern sides) into 1 l capacity polyethylene bottles. three bottles of the water samples were taken from each sampling site based on the types of parameters to be determined and their pretreatment requirements, in which case the first bottle was treated with 1.5 ml of conc. hno3 to ph < 2 for major and trace metal analysis and the second bottle was preserved for other physicochemical parameters at a temperature of 4 0c. the water samples were stored in an ice-box and transported later to the laboratory for analysis. 2.2.5. preparation of reagents all reagents were prepared based on the procedures given in the standard methods; e.g., ‘4500-p e. ascorbic acid method’ for phosphate, ‘4500-no3– b. ultraviolet spectrophotometric screening method’ for nitrate, ‘4500cl– b. argentometric method’ for chloride, ‘2340 c. edta titrimetric method’ for hardness, ‘4500-no2– b. colorimetric method’ for nitrite and ‘4500-nh3 c. titrimetric method’ for nh3, ‘section 2320 b. titration method for alkalinity (hco3alkalinity and co32alkalinity) and ‘4500-so42– e. turbidimetric method’ for so42– (apha, 1999). 2.2.6. preparation of stock and working standard solutions the stock standard solutions of each of the metals of interest were prepared at the concentrations of 1000 mg l-1. accordingly, 1000 mg l-1 solution was prepared for each parameter by dissolving 2.5 g caco3 for ca, 2.563 g mgso4.7h2o for mg, 1.23 g alcl3 for al, 1.75 g fe(nh4)2so4.6h2o for fe, 0.72 g kmno4 for mn, 1.1 g znso4.7h2o for zn, 0.45 g cdcl2.2h2o for cd, 0.4 g pb(no3)2 for pb, 1.92 g cr(no3)2.9h2o for cr, 1 g co(no3)2 for co, 1.23 g ni(no3)2.6h2o for ni, 0.635 g nacl dried at 140 0c for na, 0.477 g kcl dried at 110 0c for k in 1 l distilled water and diluting to 250 ml in all cases. moreover, 1000 mg l-1 solution was also prepared by dissolving 1.479 g na2so4 (anhydrous) in 1 l distilled water and diluting it to 1000 ml of the stock standard solution of so42-. for no3-, 1000 mg l-1 solution was prepared by dissolving 0.18045 g kno3 (dried at 105 0c for 24 h) in 1 l distilled water and diluting to 250 ml according to ‘4500no3–b.3b ultraviolet spectrophotometric screening method’ of apha (1999). for po43-, 1000 mg l-1 solution was prepared by dissolving 1.097 g kh2po4 in 1 l distilled water and diluting to 250 ml according to ‘section 4500p.c.3e’ of apha (1999). for no2-, 250 mg l-1 solution was prepared by dissolving 0.308 g nano2 in distilled water and diluting it to 250 ml according to ‘4500-no2– b. colorimetric method’ of apha (1999). for f-, 100 mg/l solution was prepared by dissolving 0.05525 g naf in distilled water and diluting it to 250 ml according to ‘4500f– c ion-selective electrode method’ of apha (1999). the working intermediate standard solutions, 100 mg/l for metals, 10 mg/l for po43and f-, and 50 mg/l for no3-, no2and so42were prepared by diluting 10 ml (metals, f-), 1 ml (po43-), 20 ml (no2-) and 5 ml (no3-, so42-), respectively, of the respective individual stock standard solutions with distilled water to a 100 ml volume. 2.2.7. calibration of the standard solutions the instruments used in this analysis were calibrated using the calibration standard solutions with respect to the analyte concentrations. standard solutions of each analyte of six points (including calibration blank for metals, po43-, no3-, no2-), five points (including calibration blank for so42-) and four points (for f-) were prepared from their respective working intermediate standard solutions. these calibration standard concentrations were within the working linear range of the instrument used for analysis. beginning with the blank and working toward the highest standard, the solutions were aspirated, the readings were recorded, and the linearity was checked with the linear regression of excel software 2007 and a visual inspection of the line. the prepared calibration standard solutions for each analytes are shown in table 1. 2.2.8. preparation of blanks a solution of distilled water and 2% (v/v) hno3, distilled water treated with 1 ml of 8.3% (v/v) hcl, distilled water treated with 4 ml of ammonium molybdate solution and 0.5 ml of stannous chloride reagent, distilled water plus 5 ml of conditioning reagent (prepared from isopropyl alcohol, na2so4, nacl, conc hcl and glycerol) and distilled water plus 5 ml conc. h2so4 were, respectively, used as calibration blanks for metals, no3-, po43-, so42 and no2determination. furthermore, a solution of 3 drops of erichrome black t (ebt) and distilled water, distilled water plus 3 drops of 0.1% methyl red indicator were used, haile arefayne east african journal of sciences volume 12 (2) 101-110 104 respectively, as a blank for the determination of hardness, alkalinity, chloride and ammonia in the sample. table 1. prepared calibration standard solutions: blank (s0), standard 1 (s1), standard 2 (s2), standard 3 (s3), standard 4 (s4), and standard 5 (s5) for each analyte. analytes calibration standard solutions (mg/l) s0 s1 s2 s3 s4 s5 na 0 5 10 15 20 25 k 0 5 10 15 20 25 mg 0 0.5 1 5 10 15 ca 0 0.5 1 5 10 15 fe 0 0.2 0.4 0.6 0.8 1.0 zn 0 0.2 0.4 0.6 0.8 1.0 mn 0 0.2 0.4 0.6 0.8 1.0 al 0 0.5 1 5 10 15 cd 0 0.2 0.4 0.6 0.8 1.0 cr 0 0.2 0.4 0.6 0.8 1.0 co 0 0.2 0.4 0.6 0.8 1.0 pb 0 0.2 0.4 0.6 0.8 1.0 ni 0 0.2 0.4 0.6 0.8 1.0 no30 2.5 5 10 15 20 po430 0.4 0.8 1.2 1.6 2 no20 5 10 15 20 25 so420 2.5 5 7.5 10 f0.01 0.02 0.03 0.04 note: the reason for the use of different calibration standard concentrations for the different species is the detection limit of the instrument used in this work. 2.2.9. sample analyses duplicate analyses were carried out on the samples for the determinations of the amounts of physicochemical (ph, ec, turbidity, total hardness, total alkalinity, organic carbon, tds, ts, ca2+ hardness, mg2+ hardness, hco3 alkalinity, co32alkalinity), the concentrations of major and trace metals (na, k, mg, ca, fe, zn, cu, mn, cd, cr, pb, al, co, ni) and inorganic nonmetals (no3-, po43-, no2-, so42-, nh3, f-, cl-). 2.2.10. in situ sample analysis temperature: a mercury thermometer (0-1000c) was used to measure the temperature of the lake water. readings were therefore made by immersing this instrument long enough into the water to allow complete equilibration (apha, 1999). classical methods of analyses: the parameters including hardness (ca2+ and mg2+ hardness, edta titrimetric method ‘section 2340 c’), chloride (argentometric method ‘section 4500-cl– b’), alkalinity (hco3alkalinity and co32 alkalinity, ‘section 2320 b. titration method’), organic carbon (5310 b. high-temperature combustion method), nh3 (4500-nh3 c. titrimetric method), and tds (2540 c. tds dried at 180 °c method) were determined following the procedures reported by apha (1999). instrumental methods of analyses: ph was measured using a ph-meter according to ‘4500-h+ b. electrometric method’ of apha (1999). the ph-meter was calibrated, before measuring ph of the water samples, using a buffer solution of ph 4.0 and 7.0. in this case, the buffer solution was prepared by dissolving one buffer tablet in a 100 ml volume of distilled water. electrical conductivity (ec) was also measured with a conductivity meter. the ec meter was calibrated using 0.01 m kcl solution according to manufacturer’s instruction manual. similarly, turbidity was also measured with turbidimeter. the turbidimeter was calibrated according to the procedures given in‘2130 b. nephelometric method’ of apha (1999). uv-vis spectrophotometer was used for the determination of po43(at 880 nm, 4500-p e. ascorbic acid method), no2(at 543 nm, 4500-no2– b. colorimetric method) and so42(at 420 nm, 4500-so42– e. turbidimetric method). determination of no3– was made by uv absorption at 220 nm according to ‘4500-no3– b. ultraviolet spectrophotometric screening method’ of the standard method of apha (1999) for which the measurement made at 275 nm was used to correct the no3– value. the major and trace metals were determined with flame atomic absorption spectrophotometer (faas). the faas was calibrated using a blank and five series of working standard solutions of each metal. finally, ion selective electrode method was used for the determination of f-. the ion selective-meter was calibrated with four series of working standard solutions of fluoride according to ‘section 4500-f– c’ of apha (1999). software packages: the software used in this paper was the gw_chart. this software was used to identify the origin and geochemical composition of water resources. accordingly, the origin and geochemical composition of the lake water were identified using the piper diagram produced based on the laboratory measurements. 3. results and discussion physico-chemical analysis: the mean values of the physicochemical parameters were obtained from duplicate analyses of the lake water samples and the results (mean ± sd) are given in tables 2-4. temperature: temperature is one of the essential parameters in water because of its influence on water chemistry. the rate of chemical reactions increases with the increase in water temperature (shishaye and nagari, 2016). similarly, the average temperature value of lake adele water was found to be 23.6 oc, which is beyond the maximum recommended values for drinking purposes (15 oc). this is, therefore, an indicator of high chemical reactions within the lake water. ph: the ph levels of the three samples taken from the lake were measured in duplicate and the average of haile arefayne lake water suitability for domestic and agricultural purposes 105 measurements was found to be 8.17, showing a slightly basic reaction. the mean ph value of the lake water is in fact within the allowable ph limits for drinking water quality, which is 6.5 8.5 (who, 2011). however, apparently, it is gradually getting closer to the maximum tolerable level. electrical conductivity (ec): the mean ec value of the study area was found to be 1447.6 μs/cm, which is beyond the values given in the epa guidelines for drinking and irrigation water quality (epa, 2003). in general, the mean ec value measured in the area indicates that lake adele water is at its maximum level in terms of irrigation water quality whereas it cannot be used for drinking purposes, for it is beyond the maximum contaminant level of drinking water standards. total dissolved solids (tds): the measured tds levels in lake adele have a mean value of 990 mg/l. this is by far beyond the maximum contaminant limit, 500 mg/l (who, 2011). thus, this maximum tds level indicates that lake adele has palatability problems. total alkalinity (ta): the ta values in this study were measured due to methyl orange alkalinity (ph 4.5), for the phenolphthalein alkalinity expected at ph 8.3 in all samples were zero. therefore, the observed alkalinity was due to hco3-. the ta value of the lake water was, thus, found to be 425±7.07 mg/l, which is similar to the hco3alkalinity, and it is greater than the maximum permissible value for drinking water (ethiopia, 2011). in this case, this high level of bicarbonate alkalinity could be the major controlling factor for the ca and mg ions concentrations in the lake water. total hardness (th): the mean value of th of the lake water was found to be 205 mg/l, which is greater than the maximum drinking water quality standards (who, 2011). this shows that the water of the lake needs to be treated before using it for drinking purpose. th is the sum effect of ca2+ hardness and mg2+ hardness. in this study, the mean values of ca2+ and mg2+ hardness were found to be 82 mg/l and 123 mg/l, respectively. turbidity: the mean value of turbidity of the lake water was found to be 43 ntu. according to who (1997), the median turbidity should be ideally below 1 ntu and turbidity in excess of 5 ntu is not recommended for drinking purposes. accordingly, the mean turbidity value measured in lake adele was found to be beyond the maximum contaminant limit. organic carbon (oc): the mean value of organic carbon content in the lake water was found to be 333.34 mg/l. it indicates that the amount of organic molecules measured as carbon present in the water of the lake is high, which is beyond the maximum contaminant standards set by epa (2003). major chemicals (inorganic nonmetals) the concentrations of inorganic nonmetals were also obtained from duplicate analyses of the samples and the results (mean ± sd) are given in table 3. sulphate (so42-): so42is a major anion that could be found in natural waters. in water, so42is expected to come from atmospheric deposition, industrial runoff, and natural sources such as gypsum (caso4. 2h2o) and anhydrite (caso4) (maiti, 2004; saadeh, 2012). the mean level of so42ion in this study was measured to be 0.19 mg/l, which is less than the taste threshold value, 250 mg/l (who, 2011). chloride (cl-): according to this study, the mean cl concentration in the lake water was found to be 105 mg/l. it is a level which is by far below the maximum contaminant level, 250 mg/l (who, 2011). nitrate (no3-1): nitrate concentrations in excess of 45 mg/l as no3or 10 mg/l as no3-n could cause a disease called methemoglobinemia (who, 2011). the average concentration of nitrate in the water source under consideration (measured as no3-n) was found to be 18.1 mg/l. the obtained result is above the maximum recommended value for drinking water supply, 10 mg no3n /l (who, 2011). this high level of nitrate in the lake could be due to the application of inorganic nitrogen fertilizers in the farms within the lake watershed. phosphate (po43-): the level of po43in the study area was found to be 0.04 mg/l. in fact, there is no guideline that lists criteria for the acceptable phosphorus levels in drinking water quality (nollet, 2007). however, the level of po43in the lake water can be considered low. nitrite (no2-): the no2concentration in lake adele was found to be 30.67 mg/l. according to who (1997), the presence of nitrite in water may mainly result from excessive application of fertilizers. this justification is also true in this study area. farmers in the lake watershed produce crops through irrigation using water from the lake, such as vegetables, maize, sorghum, (katha edulis forsk.) etc. in this connection, fertilizer applications to farm lands may have increased the concentration of nitrite ion in the lake water through runoff during rainy seasons. as far as the comparison of the no2concentration of the lake with the universal standards is concerned, it was found to be far beyond the maximum contaminant standard, 0.1 mg/l (who, 1997). fluoride (f-): the maximum contaminant limit of fluoride ion in water is 1.5 mg/l (who, 1997; epa, 2001). the f concentration in the investigated lake water was found to be haile arefayne east african journal of sciences volume 12 (2) 101-110 106 1.89±0.15 mg/l, which is a little beyond the maximum contaminant standard. therefore, the lake water is not recommended for drinking purposes, unless it is treated well to remove the high level of f-. ammonia (nh3): similar to nitrite, the concentration of nh3 in the investigated lake was found to be far beyond the maximum contaminant standards. according to epa (2001), the recommended maximum permissible value of ammonia for drinking water is 0.5 mg/l. however, the average concentration of nh3 in lake adele was found to be 301 mg/l. therefore, the lake water needs treatment with regard to ammonia removal. major and trace metals: the concentrations of major and trace metals were obtained from duplicate analyses of the samples and the results (mean ± sd) are given in table 4. sodium (na+): the na ion concentration in the study area was found to be 185.65 mg/l. though the value is large, it was found to be below the maximum contaminant level, 200 mg/l (who, 2011). potassium (k): from this study, the average concentration of k was found to be 0.99±0.22 mg/l. potassium tends to be "fixed" in soils and there are no implications of toxicity with regard to potassium (epa, 2001). calcium (ca): the mean concentration of ca in the investigated water source was also measured to be 11.15±1.47 mg/l and it is below the recommended maximum value for drinking water, 40 mg/l (who, 2011). magnesium (mg): the mean level of mg in the lake under consideration was found to be 14.74 mg/l. this value is well below the ethiopian ministry of health and who drinking water quality standard, which is 150 mg/l (emh, 2011; who, 2011). aluminum (al): the determined concentration of al in lake adele is 5 mg/l. according to epa (2001), the recommended limit for al in drinking water is 200 µg/l or 0.2 mg/l. however, the mean value of the al concentration in lake adele is far beyond the contaminant standards. therefore, the lake water needs treatment to minimize the levels of al to the standard. iron (fe): the obtained mean concentration of fe in the lake water was 0.27 mg/l. the recommended maximum value for drinking water is 0.3 mg/l (who, 2011). therefore, in comparison to the local and universal standards, the level of fe in lake adele was found to be below the maximum contaminant level, even though it is very close to the maximum standard. zinc (zn): the zn concentration in the lake under consideration was found to be 0.01mg/l. this is below the maximum limits for the quality of drinking water (who, 2011). manganese (mn): mean concentration of mn in the lake water was found to be below the method detection limit (nd). it is, therefore, below the maximum recommended limit set for drinking water quality (who, 2011). cadmium (cd): the level of cd in the lake water was also found to be below the method detection limit. therefore, this can show us that the measured level is below the usepa primary drinking water standard (2012) and the canadian drinking water quality (2003) for cd, which is < 0.005 mg/l. therefore, there is no problem concerning cd in the lake water. chromium (cr): the mean cr concentration in the studied water body was found to be 0.05 mg/l. this level of cr shows a concentration below the maximum permissible value recommended for domestic water supply purposes (who, 2011). lead (pb): according to epa (2001), the recommended limit for pb in drinking water is 10 µg/l. however, the concentration of pb in the investigated water body was found to be 0.07 mg/l, which is far beyond the maximum tolerable level for drinking. nickel (ni): the concentration of ni in the lake under consideration was found to be below the method detection limit (nd), which is below the recommended limit for ni in drinking water, 20 µg/l (epa, 2001). cobalt (co): from this study, the mean concentration of co was found to be 0.02 mg/l. co is rarely found in natural waters; accordingly, there are few recommendations as to its limitations (epa, 2001). origin and geochemical composition of lake adele: the origin of lake water could either be precipitation or groundwater. an aquifer can yield water to the surface of the earth in the form of spring due to the naturally applied pressure and the geological discontinuities within the formation/groundwater storages underneath. the spring water can, therefore, be accumulated in a localized area of land and can be called a lake. in this case, the geochemical composition of lake water is associated with its origin (shishaye & nagari, 2016). a piper diagram is a very important tool to identify the origin and geochemical composition of water bodies (fig. 2). there are different software used to simulate the origin and geochemical composition of water resources, taking the ionic concentration values of the major cations and anions as model inputs. in this paper, the origin and geochemical composition of lake adele were simulated using the gw-chart software. the levels of six ion groups, i.e. calcium, magnesium and sodium plus potassium cations; sulfate, chloride and haile arefayne lake water suitability for domestic and agricultural purposes 107 carbonate plus hydrogen carbonate anions and the tds values were considered in the plot. accordingly, the origin of lake adele water was found to be deep groundwater with a major geochemical composition of sodium bicarbonate, i.e., deep groundwater influenced by ion exchange (fig 3). in general, the simulated values of the origin and geochemical composition of the lake water were found to be in line with the laboratory results. i.e, according to the laboratory results, the alkalinity level of the lake water was found to be high and the observed alkalinity was due to hco3-. the ta value of the lake water was also found to be as equal as the hco3alkalinity, 425±7.07 mg/l, which is beyond the maximum permissible values designed for drinking purposes. therefore, this result indicates that the lake water contains high bicarbonate values as it is also shown in the piper diagram below (fig. 3). the high values of hco3alkalinity can also react with the hydrogen ions from water and raise the ph levels of the lake water, which can be clearly seen in the study area. the major controlling factors for the high levels of bicarbonate and other related ions could, therefore, be the regional geology and weathering processes. figure 2. reference trilinear diagram, modified from (manoj et al., 2013) figure 3. piper diagram of the lake adele suitability of the lake water for irrigation: irrigation water could either be from surface water or groundwater. however, regardless of the source, its quality needs to be within the international standards. irrigation water quality can be determined through laboratory analysis and some analytical formulations. some of the important factors used to determine irrigation water suitability are ph, salinity hazard, sodium hazard (sodium adsorption ratio), and the percent sodium. the lake adele water was therefore analyzed for its suitability for irrigation purposes in terms of these factors. salinity and ph: in terms of salinity, lake adele was found to be very close to the maximum standard set by the who. the measured ec level was for example close to the maximum contaminant limit of salinity for irrigation purposes, 2000 μs/cm (ayers and westcot, 1994). moreover, the ph level of the lake water was also found to be very close to the maximum standard for irrigation water, 8.5 (ayers and westcot, 1994). therefore, using this lake water for irrigation purposes without any pre-treatment may cause a long-term problem of soil salinity and alkalinity. sodium adsorption ratio: as discussed above, sodium adsorption ratio (sar) is also another factor used to evaluate irrigation water suitability. sar can be calculated using the following formulae: (1) where: na+, ca2+ and mg2+ are in meq/l. accordingly, the sar of the water in lake adele was calculated as: sar = = 18 (2) the result is showing that the sar of the lake water is at its medium level of sodium hazard. a sar value within the range of 10-18 may lead to amendments and leaching activities, for it has a medium level sodium hazard; while, sar>18 is not suitable for irrigation purposes (ayers and westcot, 1994). therefore, lake adele is classified as unsuitable water for irrigation purposes. i.e., the lake water needs to be treated before being used for irrigation purposes. however, farmers in the lake watershed are still using the lake water for agricultural purposes traditionally. therefore, the concern of the use of this contaminated water for irrigation purposes is not only the decrease in productivity but also a long-term problem of soil salinity and sodicity, which will require additional investments for soil treatment. haile arefayne east african journal of sciences volume 12 (2) 101-110 108 percent sodium: percent sodium (ps) is also another measure of water quality analysis for irrigation purposes. the equation used to calculate the percent sodium is: (3) where: na+, ca2+ k+ and mg2+ are in meq/l. the level of the ps of irrigation water should be less than 60 (ayers and westcot, 1994). however, the ps of the lake adele water was found to be 90.2%, which is beyond the maximum recommended level for irrigation purposes. therefore, lake adele also requires treatment to reduce the levels of ps, for it is not suitable in its current quality status. table 2. mean ± sd (in mg/l, oc, µs/cm, ntu) values of physico-chemicals in the samples of lake adele water in eastern ethiopia. parameter to ph ec turbidit y th ca2+ hardn ess mg2+ hardness ta hco3 alkalinit y organic carbon td s concentrat ion 23.6oc 8.17±0.00 7 1477.6±0.00 43±4.24 205±7.1 82±2. 83 123±4.24 425± 7 425±7.1 333.34±9. 4 990 table 3. mean ± sd (in mg/l) values of major chemicals (inorganic nonmetals) in the samples. analytes no3no2po43so42clfnh3 conc. 1.81±0.00001 30.67±1.89 0.04±0.003 0.19±0.02 105±3.54 1.89±0.15 301±9.9 table 4. mean ± sd (in mg/l) values of major and trace metals in the samples. analyt e na k ca mg al fe zn mn cr co ni pb cd conc. 185.7 ±0.2 1 ±0.00 11.15 ±1.5 14.74 ±0.02 5 ±2.95 0.27 ±0.02 0.01 ±0.002 nd 0.05 ±0.006 0.02 ±0.003 nd 0.07 ±0.001 nd 4. conclusion this study has revealed that the origin of lake adele is deep groundwater with a major geochemical composition of sodium bicarbonate. the results of the hydro-chemical analyses demonstrated that the water of lake adele is contaminated by hazardous chemicals and rapidly deteriorating in quality making it dangerous to use for both domestic and irrigation purposes without treatment. this is because most of its key chemical constituents are beyond the tolerable limits of water quality standards as set by such international organizations such as the european union, australian standards, who and usepa. the levels of turbidity, nitrate (no3-1), nitrite (no2-), ammonia (nh3), and lead (pb) have been found to be too high to use the water for domestic purposes such as drinking and cooking. salinity, ph, and sodium adsorption ratio (sar) of the water were also found to be beyond the tolerable levels of irrigation water quality standards. however, farmers in the study area have been intensely using the lake water for both drinking and irrigation purposes without any relevant treatment. this would predispose the farmers and other members of the community to the risk of health hazards due to direct consumption of the water as well as vegetables, khat, or other food produced through irrigation that contain too high levels of nitrate, nitrite, lead, and other heavy metals. therefore, policy makers and development agents need to create community awareness in the study area on the dangers of using the lake water for drinking as well as irrigation and make campaigns of sanitizing and treating it through judicious and sustainable utilization. future research should focus on identifying sources of the contaminants to design a strategy for controlling them at their origins and promoting sustainable management of the lake. 5. references apha. 1999. standard methods for the examination of water and wastewater, 20th edition, american public health association, american water works association and water environment federation, washington, d.c., usa. ayers, r. s. and westcot, d. w. 1994. water quality for agriculture, fao irrigation and drainage paper. food and agriculture organization of the un rome, isbn 92-5-102263-1. belay, g. 2006. numerical groundwater flow modelling of the adelle-haramaya dry catchment (east hararghe, oromia regional state). addis abeba university. branchu, p., bergonzini, l., ambrosi, j.-p., cardinal, d., delalande, m., pons-branchu, e. and benedetti, m. 2010. hydrochemistry (major and trace haile arefayne lake water suitability for domestic and agricultural purposes 109 elements) of lake malawi (nyasa), tanzanian northern basin : local versus global considerations. hydrol. earth syst. sci. discuss., 7: 4371–4409. epa. 2001. parameters of water quality interpretation and standards. published by the environmental protection agency, ireland. epa. 2003. drinking water quality standards, edstrom industries, waterford, wi 53185-5913. ethiopian ministry of health (emh) 2011. national drinking water quality monitoring and surveillance strategy, the federal democratic republic of ethiopia, ministry of health,addis ababa, ethiopia. kebede, k. 2013. groundwater in ethiopia, features, numbers and opportunities, springer hydrogeology. heidelberg new york dordrecht london, isbn: 978-3-642-30390-6. liu, f., song, x., yang, l., zhang, y., han, d., ma, y., and bu, h. 2015. identifying the origin and geochemical evolution of groundwater using hydrochemistry and stable isotopes in the subei lake basin, ordos energy base, northwestern china. hydrol. earth syst. sci., 19: 551–565. maiti, k. s. 2004. handbook of methods in environmental studies, water and wastewater analysis 2nd edition. jaipur, india: abd publishers. manoj, k. ghosh, s., and padhy, p. k. 20113. characterization and classification of hydrochemistry using multivariate graphical and hydro-statistical techniques. research journal of chemical sciences, 3 (5): 32-42. nollet, l. m. 2007. handbook of water analysis 2nd edition: taylor and francis group, crc press, boca raton, florida, usa. olana, k. y. 2014. assessment of climate change impacts on highland lake of eastern ethiopia. international journal of scientific and eng. research, 5 (6): 1-12. ranjan, r. 2012. water quality monitoring of groundwater resources around sugar factory, near east-west champaran border, bihar, india. res. j. chem. sci., 2 (7): 79-81. saadeh, m., semerjian, l. and amacha, n. 2012. physicochemical evaluation of the upper litani river watershed, lebanon. the scientific world journal 46: 18. setegn, s. g. 2012. information and modeling systems for sustainable water resources management. in information and modeling systems for sustainable water resources management. addis abeba: ftu, global water for sustainability program, 12: 1–52. shishaye, h. a. 2017. water quality analysis and evaluation using graphical methods: a case of lake beseka. ethiopian journal environmental studies and management, 10 (8): 1054-1070. shishaye, h. a. and nagari, a. 2016. hydrogeochemical analysis and evaluation of the groundwater in the haramaya well field, eastern hararghe zone. ethiopia. j. hydrogeol. hydrol. eng.,5 (4): 1-15. tiwari, m. and ranga, m.m. 2012. assesment of diurnal variation of physico chemical status of khanpura lake, ajmer, india, res. j. chem. sci., 2 (7): 69-71. usepa. 2012. drinking water standards and health advisories, epa 822-s-12-001, office of water, u.s. environmental protection agency, washington, d. c., usa. who. 1997. guidelines for drinking-water quality 2nd edition, volume 3. world health organization, surveillance and control of community supplies, geneva. who. 2011. guidelines for drinking-water quality 4th edition, new york, usa: unicef and the world health organization. haile arefayne east african journal of sciences volume 12 (2) 101-110 110 east african journal of sciences (2019) volume 13 (1) 7-14 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: ykindie2007@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) participatory evaluation of faba bean (vicia faba l.) varieties for yield and yield components in wag-lasta, eastern amhara, ethiopia yirga kindie* and zinabu nigusie amhara regional agricultural research institute (arari), sekota dryland agricultural research center, directorate of plant science, p.o. box, 62, sekota, ethiopia. abstract: currently faba bean is out of production due to pest and diseases as well as shortage of high yielding and widely adapted varieties. therefore, participatory variety selection was conducted at lalibela, hamusite and dehana districts of wag-lasta on both trial station and on farmer’s field, in 2016 main cropping season, to evaluate and select high yielder faba bean varieties involving farmers. eight released faba bean varieties (walki, moti, cs-20dk, obsie, dosha, tumsa, gora, and hachalu) including a local check were tested using randomized complete block design with three replications at on station of each trial site. the mother trial was done at trial stations, whereas the baby trials were done at three farmer’s field per districts. as anova revealed that, significant differences (p<0.01) were observed among varieties for plant height, pods per plant, seeds per pod, 100seeds weight and grain yield. among the tested varieties, variety dosha (2722.20kgha-1 & 2197.90kgha-1) was superior in grain yield at both lalibela and hamusite district respectively whereas, higher grain yield was recorded from cs-20dk (2329.17kgha-1) & tumsa (1927.08kgha-1) varieties at dehana. the local variety was lower yielder (1143.66kgha-1) at dehana. dosha as preferred by farmers that scores higher mean value (59.83 & 45.67) at lalibela and hamusite respectively whereas least mean value was recorded from local (24.50) variety. while the maximum score (55.8) was recorded on cs-20dk variety at dehana. therefore, based on farmers’ preference value and biological data, dosha variety was selected for production in lalibela and hamusite districts while cs-20dk was selected for production in dehana districts. keywords: baby trial; faba bean; mother trial; participatory 1. introduction legumes are important components of various farming systems in the world. faba bean is one of the earliest domesticated cool season food legumes in ethiopia. ethiopia is the second largest faba bean producer in the world next to china (teklay et al., 2014). in addition to food faba bean plays a great role in every aspect of ethiopian life not only as food but also the straw and the seed as feed for animals as well as straw or haulms as firewood, green manuring and silage-making (comlanvi, 2011). besides this, it plays an important role in the restoration of soil fertility through atmospheric nitrogen fixation, that provides agricultural sustainability (agegnehu and fessehaie, 2006; ronner et al., 2013). faba bean is the first among pulse crops cultivated in ethiopia and leading protein source for the rural people and used to make various traditional dishes (emiola and gous, 2011; asnakech et al., 2017) and also serves as sources of foreign currency to the country (shahidure et al., 2010; agegnehu and fessehaie, 2006). in ethiopia, pulse crops are grown annually on approximately 1652 844.19 hectares of land, of these, 443 966.09 hectares were covered by faba bean, with annual production of 8 486 545.69 quintals (csa, 2016). in waghimra zone, faba bean production covers about 6 153.58 hectares of land, within 39 634 numbers of holders with its production of 51 587.89 quintals or 8.38qtha-1 (csa, 2016). in spite of huge area coverage and its importance, the productivity of faba bean is about 1.912tha-1, far below crop’s potential > 5 tha-1 (csa, 2016). this may be to different biotic and abiotic factors, the use of old and low yielding genetic potential of the wildly growing local cultivars and unavailability of high yielder cultivars (anteneh et al., 2018; tafere et al., 2012). participatory variety selection (pvs) is a more rapid and cost-effective way of identifying farmer-preferred varieties and it ensures the adoption of new varieties (witcombet et al., 1996). in addition to this, farmers’ participation in varietal selection provides adequate exposure to new varieties and high rate of replacement, strong extension network, that generally gave farmers access to new cultivars, to maximize their productivity and to improve the livelihood of their families (tafere et al., 2012). moreover, participatory research increases the job efficiency of the scientists and farmers' knowledge, that enables to be retained effectively from year to year (wondimu, 2016; tafere et al., 2012). therefore, this study was initiated to evaluate and select high yielder faba bean variety/ varieties, through farmers’ participation. 2. materials and methods 2.1. description of the study area the experiment was conducted at the major faba bean producing areas (lalibela, hemusite and dehana) of wag-lasta both on trial station and on farmer’s field. lalibela is located in north wollo zone while both hamusite and dehana are located in yirga and zinabu east african journal of sciences volume 13 (1) 7-14 8 waghimra zone at sekota zuriye and dehana ward respectively. table 1. description of the locations used for evaluation of faba bean varieties. location altitude rainfall soil type lalibela 2400masl 895.2mm black (vertisol) hamusite 2200masl 774.3mm black sandy dehana 2400masl 998.2mm black 2.2. treatments and design eight improved faba bean varieties (walki, moti, cs20dk, obsie, dosha, tumsa, gora, and hachalu) obtained from holleta agricultural research center including local check were tested in randomized complete block design (rcbd) within three replications. mother trials were planted at the trial site of each location and other three farmer fields were planted with one replication each, considered as baby trials at each location. the trial was planted on plot size of 3m *2.4m within six rows. spacing between replication, plots, rows, and plants was 1m, 0.5m, 0.4m, and 0.1m respectively. local checks of respective locations were used as checks at each trial site. three farmers field was used for evaluation and used as a replication. sowing was done during onset of rainfall with the application of diammonium phosphate (dap) fertilizer at the recommended rate of100 kgha-1 and seed rate of 175kgha-1. 2.3. data collection agronomic data were collected on plot and plant basis from the mother trial. hundred seed weight (g), plant height (cm), number of branches per plant, number of pods per plant, and number of seeds per pod, were evaluated on five randomly taken plants from the middle four rows in each plot. biomass (g) and grain yield (g) of the middle four rows in each plot was measured and converted to kilogram per hectare for analysis. farmers’ evaluation and selection data were collected on plot basis from the three baby trials of each trial location. the selection was carried out at two different growth stages (at the start of flowering and physiological maturing). 9 agricultural development agents, 26 men, and 8 women farmers have participated in the selection process. the ranking procedures was explained to agricultural development agents and farmer participants, as well as they have discussed and set the selection criteria ranging from 1 to 5 (5 = very good, 4 = good, 3 = average, 2 = poor and 1 = very poor) for each variety. 2.4. data analysis the recorded agronomic data were subjected to the analysis of variance (anova) using statistical analysis system (sas 9.1.3) and mean separation was carried out using least significant difference (lsd) test at 5 % probability level. farmers’ selection data were analyzed using the simple ranking method; the ranking was done on consensus where differences are resolved through discussion in accordance with the given value (de boef and thijssen, 2007). 3. results and discussion 3.1. analysis of agronomic traits, yield components, and farmer's preference at lalibela agronomic traits, i.e., days to flowering, days to maturity, plant height, number of primary branches per plant and yield components (number of pods per plant, number of seeds per pod, biomass, grain yield and hundred seed weight) were analyzed (table 2). analysis of variance showed that highly significant difference (p ≤ 0.01) was observed among tested faba bean varieties in plant height. the maximum plant height was recorded from tumsa, gora, and dosha varieties with a height of 117.40 cm, 116.33 cm and 110.67 cm respectively; while the shortest plant height (89.10 cm) was recorded on local variety (table 2). this result was in line with the work of teame et al.(2017)who reported that hachalu (120.70 cm)and dosha (110.00 cm) varieties were the longest and local variety was shortest at the southern zone of tigray regional state. the analysis of variance revealed that there was a highly significant difference among faba bean varieties regarding the number of branches per plant and the highest number (2.90) was recorded from cs-20dk and gora varieties, followed by dosha (2.70) variety (table 2). number of pods per plant and seeds per pod were significantly affected by varieties (p ≤ 0.01). the maximum number of pods per plant and seeds per pod were recorded on variety dosha with a mean score of 20.50 and 3.07 respectively, but the lowest pods and seeds were scored from a local variety (table 2). likewise, teame et al.(2017)and tafere et al.(2012) reported the significant difference among faba bean varieties as regard as the number of pods per plant and seeds per pod. the varieties significantly (p ≤ 0.01) varied for 100 seed weight, indicating the variations among varieties. of all tested varieties, gora, moti and hachalu produced the heaviest seeds with an average mean score of 85.50g 82.67g and 80.83g respectively. whereas, the lowest 100 seed weight(42.00gm) was recorded from a local variety (table 2). ashenafi and mekuria (2015) also reported the significant difference among faba bean varieties in 100 seed weight. the statistical analysis showed that a highly significant (p ≤ 0.01) difference within the tested varieties on grain yield. the maximum grain yield (2722.20kgha-1) was harvested from dosha variety, followed by hachalu (2579.90kgha-1) and tumsa (2444.40kgha-1), while the lost grain yield (1228.20kgha-1) was recorded from a local variety (table 2). dosha variety had a yield advantage of 121.64%, over the local variety. this result agreed with teame et al. (2017) who reported that the highest grain yield was obtained on varieties dosha and tumsa, which was 3891.00 and 3437.00kgha-1, respectively and dosha had 55.45% yield advantage over local variety. ashanafi and makuria(2015) had also reported yield variation from 3703.7 – 4886.8kgha-1 and 3436.2 – 4701.6kgha-1 in agarfa and sinana trial sites respectively. yirga and zinabu evaluation of faba beans (vicia faba l.) varieties for yield and yield components 9 3.1.1. farmer’s variety evaluation three agricultural development agents, 10 men, and 4 women farmers have participated in the selection. they set the criteria; plant establishment, overall performance, stem strength, pod setting, earliness and seed size to select the best variety. dosha (59.83) scored the highest value and the lowest was scored by local (24.5). hachalu (57.5) and gora (56.67) were ranked as second and third best varieties by farmers, respectively (table 3). in line with this finding, teame et al.(2017) stated that dosha was selected as top ranking or adapted variety by farmers’ selection. the same variety had better performance and was high yielder from the analysis of researchers’ collected data. table 2. mean grain yield and other agronomic traits of faba bean at lalibela. variety df dm ph(cm) brp pdp spd bm(kgha-1) gy(kgha-1) sw(g) walki 59 102 109.13 2.73 20.33 2.47 7760.40 1929.70 57.50 moti 57 107 104.53 2.40 14.33 2.53 8437.50 1553.10 82.67 cs-20 dk 59 103 110.60 2.90 15.07 3.00 7929.70 1910.90 58.00 obsie 58 107 103.23 2.60 12.23 2.40 7838.50 2100.70 77.33 dosha 61 104 110.67 2.70 20.50 3.07 9583.30 2722.20 77.17 tumsa 61 109 117.40 2.50 14.80 3.00 10000.00 2444.40 79.33 gora 61 108 116.33 2.90 13.17 2.90 10000.00 2269.50 85.50 hachalu 61 105 110.07 2.53 15.63 2.70 9583.30 2579.90 80.83 local 56 100 89.10 2.33 11.10 2.67 5625.00 1228.20 42.00 mean 59 105 107.89 2.62 14.79 2.75 8528.65 2082.07 71.15 lsd ns ns 9.23 ** 0.3** 2.67** 0.39** 1552.20** 294.7** 6.2** cv 4.49 3.28 4.944 6.56 10.44 8.11 10.51 8.18 5.05 note: ns=non-significant, *= significant, **=highly significant, df = days to flowering, dm = days to maturity, ph = plant height, brp = primary branches per plant, pdp = pods per plant, spd = seeds per pod, bm = biomass, gy = grain yield, sw = 100seeds weight. table 3. mean of farmers’ preference criteria on faba bean variety selection at lalibela. variety farmers criteria total mean rank pes oap sts ps er ss walk 47 33 32 32 60 22 226 37.67 5th moti 33 21 22 22 33 65 196 32.67 8th cs-20dk 33 33 49 30 32 22 199 33.17 7th obsie 36 37 34 37 33 37 214 35.67 6th dosha 69 69 69 69 46 37 359 59.83 1st tumsa 68 66 63 64 26 49 336 56.00 4th gora 66 64 58 61 26 65 340 56.67 3rd hachalu 69 60 56 64 46 50 345 57.5 2nd local 33 21 15 30 33 15 147 24.50 9th note: pes = plant establishment, oal = overall performance, sts =stem strength, ps =pod setting, er = earliness, ss = seed size 3.2. analysis of agronomic traits, yield components and farmer's preference at dehana analysis of variance revealed that plant height was significantly (p ≤ 0.01) affected by faba bean varieties. the maximum height was recorded for gora, cs-20dk, and tumsa with mean scores of 98.30 cm, 94.50 cm, 91.37 cm, respectively (table 4). in line with this finding, degife and kiya (2016) reported that variety gora was the tallest (46.6 cm) followed by variety gebelcho (46.27 cm). similarly, the highest number of branches per plant (2.73) was obtained from variety obsie followed by hachalu (2.70) and cs-20dk (2.60) varieties, respectively. the tested varieties showed significant variations for number of pods per plant and number of seeds per pod. the highest number of pods and seeds were scored for cs-20 dk, hachalu and tumsa varieties, with the average mean scores of 18.4 & 3.07, 12.7 & 2.73 and 12.47 and 2.73, respectively, but the minimum numbers (10.23 and 2.40) were recorded for the local variety (table 4). simultaneously, variety cs-20dk was the highest yielder (2329.17 kg ha-1), followed by tumsa (1927.08 kg ha-1) and gora (1890.63 kg ha-1) varieties, whereas the lost yield (1143.66 kg ha-1) was recorded for the local variety (table 4). likewise, degife and kiya (2016) and tewodros et al. (2015) had reported significant differences in the number of pods and seeds per plant, 100 seed weight, as well as grain yield among the faba bean varieties at gamo gofa and north gonder zones respectively. in dehana woreda (district), the production and productivity of faba bean was constrained by the gallforming disease, with the mean severity ranging from yirga and zinabu east african journal of sciences volume 13 (1) 7-14 10 11.87% to 38.00% among the tested varieties. likewise, anteneh et al. (2018) reported the highest mean severity (42.14%) of gall-forming disease at debark district. the highest disease mean severity was scored from local (38.00%), dosha (22.87%) and walki (19.53%) varieties, respectively, but the lowest (11.87%) had scored from gora variety (table 5). in line with this result, teklay et al. (2014) reported the significant differences in gall-forming disease severity among varieties and the importance of this disease in southern tigray. the mean score revealed that the incidence of gall-forming diseases was significantly different among the tested varieties. the maximum faba bean gall incidence was recorded for the local variety (84.4%), hachalu (64.5%) and dosha (45.0 %) varieties, while the minimum incidence was recorded for moti and tumsa varieties, with the average incidence of 23.8% and 31.2%, respectively (table 5). similarly, mekuria and ashenafi (2014) reported maximum disease incidence in degaga (44.30%), hachalu (49.99%) and gebelcho (42.26%) varieties in agarfa districts. 3.2.1 farmers’ variety evaluation three agricultural development agents, 8 men, and 2 women farmers evaluated the trial using plant establishment, biomass, stem strength, pod setting, earliness, number of branch per plant as criteria to select promising varieties. cs-20 dk (55.8), tumsa (53.0) and gora (52.0) scored the highest values, respectively and the lowest (25.5) was scored for the local variety (table 6). table 4. mean grain yield and other agronomic traits of faba bean varieties at dehana. variety df ph(cm) brp pdp spd bm(kgha-1) gy(kgha-1) sw (g) walki 53 79.67 2.40 11.07 2.67 3291.70 1587.50 53.50 moti 53 90.30 2.27 10.33 2.73 3361.10 1427.08 62.50 cs-20dk 53 94.50 2.60 18.40 3.07 3000.00 2329.17 51.33 obsie 53 88.73 2.73 10.50 3.07 3923.60 1798.61 74.83 dosha 54 85.27 2.13 8.67 2.93 3548.60 1716.67 60.17 tumsa 56 91.37 2.27 12.47 2.73 4333.30 1927.08 70.67 gora 51 98.30 2.27 10.77 3.20 3869.80 1890.63 75.83 hachalu 51 91.00 2.70 12.70 2.73 4739.60 1572.92 64.00 local 55 82.90 2.07 10.23 2.40 3395.80 1143.66 38.67 mean 53 89 2.38 11.46 2.84 3718.17 1710.97 61.28 lsd ns 7.88** 0.41* 1.25** 0.39* 510.5** 163.62** 5.36** cv 5.31 5.11 9.83 6.31 8.04 7.93 5.53 5.05 note: ns=non-significant, *= significant, **=highly significant, dm = days to maturity, ph = plant height, brp = primary branches per plant, pdp = pods per plant, spd = seeds per pod, bm = biomass, gy = grain yield, sw = 100seeds weight. table 5. average mean score of gall-forming disease incidence and severity at dehana variety mean of incidence (%) mean of severity (%) walk 36.4 19.53 moti 23.8 14.13 cs-20 dk 41.3 19.00 obsie 40.7 13.47 dosha 45.0 22.87 tumsa 31.2 10.43 gora 36.6 11.87 hachalu 64.5 14.33 locale 84.4 38.00 3.3. analysis of agronomic traits, grain yield, and farmer's preference at hamusite agronomic traits i.e., days to flowering, days to maturity, plant height, number of primary branches per plant, number of pods per plant, number of seeds per pod, biomass, grain yield and hundred seed weight, were analyzed (table 7). the varieties significantly (p ≤ 0.05) varied for days to flowering, with a mean score ranging from 40 days (dosha) to 44 days (gora and walki). this result agreed with tafere et al. (2012) who reported that days to flowering had significantly affected by variety. highly significant (p ≤ 0.01) differences were also observed among varieties for number of primary branches per plant, number of pods per plant, number of seeds per pod and biomass. likewise, tafere et al. (2012) and teame et al. (2017) reported significant differences for the number of pods and seeds per plant among the faba bean varieties they tested. mmaximum numbers of pods per plant (16.80) were harvested for dosha, followed by walki (14.27) and hachalu (13.60) varieties, while the lowest (9.20) was obtained from obsie variety. the highest number of seeds per pod was recorded from walki, dosha and gora varieties, with the mean score of 3.60, 3.53 and 3.30, respectively whereas; the minimum number of seeds per pod was obtained on local variety. the tested varieties significantly (p ≤ 0.01) varied for hundred seed weight, indicating the genetic variation among varieties. of all the tested varieties, obsie (68.50g, tumsa (63.17g) and gora (61.75g) produced heaviest seeds, respectively. yirga and zinabu evaluation of faba beans (vicia faba l.) varieties for yield and yield components 11 table 6. mean of farmers’ selection criteria and ranking of genotypes at dehana. variety farmers criteria total mean rank pes bm sts ps er br walk 46 44 40 38 44 22 234 39 7th moti 33 26 22 22 33 46 182 30.3 8th cs-20 dk 59 59 58 59 56 44 335 55.8 1st obsie 48 46 48 48 40 52 282 47 5th dosha 54 50 52 50 44 44 294 49 4th tumsa 58 56 58 56 48 42 318 53 2nd gora 54 52 54 50 46 56 312 52 3rd hachalu 48 50 42 42 42 46 270 45 6th local 33 22 20 30 33 15 153 25.5 9th note: pes = plant establishment, bm = biomass, sts =stem strength, ps =pod setting, er =earliness, br = branch number analysis of variance revealed that there was highly significance difference (p ≤ 0.01) among the tested varieties for grain yield. the maximum yield (2197.9kgha-1) was harvested from dosha variety, while local variety was the lost yielder (1687.50kgha1). walki and hachalu varieties were the 2nd and 3rd high yielder with 2079.70kgha-1 and 2031.30kgha-1, respectively. the result was in line with tewodros et al. (2015)who reported that the highest yield was obtained on varieties hachalu (2429.5kgha-1) and dosha (2226.30kgha-1). table 7. mean grain yield and other agronomic characters of faba bean varieties at hamusite variety df dm ph(cm) brp pdp spd bm(kgha-1) gy(kgha-1) sw (g) walki 44 79 96.90 3.00 14.27 3.60 2088.61 2079.70 47.67 moti 41 77 104.40 2.60 12.00 3.27 2087.64 1750.00 60.25 cs-20 dk 43 76 102.10 3.30 12.80 3.13 2086.39 1756.90 42.67 obsie 43 81 99.20 2.93 9.20 3.00 2087.35 1868.10 68.50 dosha 40 81 99.33 2.73 16.80 3.53 2088.6 2197.90 58.50 tumsa 43 77 105.53 3.70 12.80 3.20 2089.54 1729.20 63.17 gora 44 77 107.10 2.73 10.20 3.30 2087.72 1899.30 61.75 hachalu 43 81 97.40 2.40 13.60 3.13 2089.11 2031.30 52.00 local 40 77 92.10 2.27 9.83 2.53 1819.93 1687.50 32.67 mean 42 78 100.45 2.85 11.72 3.26 2058.32 1901.43 54.13 lsd 2.67* ns ns 0.49** 2.16** 0.39** 33.32** 309.45** 8.10** cv 3.67 5.45 5.31 9.87 10.62 6.98 4.94 9.40 8.62 note: ns=non-significant, *= significant, **=highly significant, dm = days to maturity, ph = plant height, brp = primary branches per plant, pdp = pods per plant, spd = seeds per pod, bm = biomass, gy = grain yield, sw = 100seeds weight. 3.3.1. farmer’s variety evaluation and criteria three agricultural development agents, 8 men, and 2 women farmers were invited to select the promising varieties. dosha, walki, and hachalu have been selected as the promising varieties by scoring 45.6, 42.0 and 41.5 values, respectively, but the lowest (25.5) value was scored by local variety. in line to this finding wondimu (2016) and tafere et al. (2012) stated that dosha was the 1st ranked variety by farmers selection. the same variety had better performance and was found to be promising. it is obvious that farmers demonstrated the ability to select well adapted and preferred varieties, under their circumstances, using their own criteria. 4. conclusion and recommendation incorporating farmers’ preferences in the selection of varieties in the breeding process may increase the adoption rate of new varieties. farmers’ exposure to evaluate and select new varieties provides an advantage to exploit their potential knowledge of identifying adapted varieties that best meet their interests. the interaction of researchers and farmers will also help to design research objectives, to overcome rejection of varieties developed by researchers alone, enhances the acceptance of varieties and reduces costs associated with variety development. the present investigation showed that the promising variety dosha gave the highest grain yield and showed best performance in other agronomic traits, than the tested varieties at both lalibela and hemusite. similarly, farmers selected dosha as the promising and adapted variety. whereas, variety cs20dk gave the highest grain yield and showed better performance at dehana. the same varieties had better performance and selected as top ranking according to farmers perception. the current selection process also demonstrated that farmers were capable of selecting important traits for grain yield and identifying superior varieties adapted to their locality. totally, pvs was effective yirga and zinabu east african journal of sciences volume 13 (1) 7-14 12 and reliable for identifying appropriate cultivars through a partnership with resource-poor farmers. dosha had recommended for lalibela, hemusite and related agro-ecologies, while cs-20dk had recommended for dehana and related agroecologies. other faba bean gall diseases management methods and resistant variety development activities should be done to increase the production and productivity of faba bean at dehana. table 8. mean of farmers’ selection criteria and ranking of varieties at hamusite. variety farmers criteria total mean rank pes oal sts ps er ph walki 47 46 46 47 40 26 252 42.00 2nd moti 30 25 22 26 33 48 184 30.67 6th cs 20 dk 30 28 25 26 32 22 163 27.17 7th obsie 40 38 34 37 36 37 222 37.00 4th dosha 49 50 47 50 38 40 274 45.67 1st tumsa 28 26 26 22 26 46 174 29.00 8th gora 32 32 30 32 38 48 212 35.33 5th hachalu 46 44 40 44 33 42 249 41.50 3rd local 33 21 15 30 33 15 147 25.50 9th note: pes = plant establishment, oal = overall performance, sts =stem strength, ps =pod setting, er = earliness, ph = plant height 5. acknowledgments the authors acknowledge socio-economic and extension directorate of sdarc, model farmers’ and das of the trial site for the technical support of this research. finally we acknowledge the amhara region agricultural research institute for financial support and sekota dry land agricultural research center for helping and facilitating us to conduct this study and come to completion with fruitful result. 6. references agegnehu, g., and fessehaie, r. 2006. reseponse of faba bean to phosphate fertilizer and weed control on nitisols of ethiopia highlands. italian j. of agronomy, 2: 281-290. anteneh ademe, yohannes ebabuye, mesganaw gelaye, solomon gezachew and getachew telahun. 2018. survey of faba bean (vicia faba l.) diseases in major faba bean growing districts of north gondar. african journal of plant science, 12(2): 32–36. ashenafi mitiku and wolde mekuria. 2015. effect of faba bean (vicia faba l.) varieties on yield attributes at sinana and agarfa districts of bale zone, southeastern ethiopia. jordan journal of biological sciences, 8(4): 281–86. asnakech tekalign, john derera, julia sibiya and asnake fikre. 2017. participatory assessment of production threats, farmers desired traits and selection criteria of faba bean (vicia faba l.) varieties. indian journal of agricultural research, 50(4): 295–302. comlanvi sitou. 2011. trends in the production, trade, and consumption of food-legume crops in sub-saharan africa. csa (central statistical agency). 2016. statistical bulletin agricultural sample survey 2015/16. report on area and production of major crops (private peasant holdings, meher season). addis abeba, ethiopia. de boef, ws. and thijssen, mh. 2007. participatory tools working with crops, varieties,and seeds. a guide for professionals applying participatory approaches in agrobiodiversity management, crop improvement,and seed sector development. wageningen, wageningen international, 83p. degife, a. z., and kiya, a. t. 2016. evaluation of faba bean (viciafaba l.) varieties for yield at gircha research center, gamo gofa zone, southern ethiopia. scholarly journal of agricultural science ,6(6): 169 –76. emiola, i. a., and gous, r. m. 2011. nutritional evaluation of dehulled faba bean (vicia faba cv . fiord) in feeds for weaner pigs. south african journal of animal science 41(2). mekuria wolde and mitiku ashenafi. 2014. evaluation of faba beans (vacia faba l.) varieties for chocolate spot (botrytis fabae l.) disease resistance at sinana and agarfa district of bale zone, southeastern ethiopia. madawalabu university. ronner esther, ken e giller and esther ronner. 2013. agronomy, farming systems and ongoing projects on grain legumes in ethiopia. shahidure rashid, yirga chilot, behute befekadu and lemma solomon. 2010. pulses value chain in ethiopia. tafere mulualem, dessalegn tadesse and dessalegn yigzaw. 2012. participatory varietal selection of faba bean (vicia faba l.) for yield and yield components in dabat district. wudpecker journal of agricultural research, 1(7): 270–74. teame gereziher, seid ephrem and diriba lemma. 2017. participatory evaluations of faba bean (vicia faba l.) varieties in enda mekoni district , northern ethiopia. african journal of agriculture, 4(2):263–68. yirga and zinabu evaluation of faba beans (vicia faba l.) varieties for yield and yield components 13 teklay abebe, birhane tsehaye, nega yemane and workineh assefa. 2014. the prevalence and importance of faba bean diseases with special consideration to the newly emerging ‘faba bean gall’in tigray, ethiopia. discourse journal of agriculture and food sciences, 2(2): 33–38. tewodros tesfaye, asfaw azanaw, getachew tilahun, kibersew mulat and samuel sahile woldemariam. 2015. evaluation of faba bean (vicia faba l.) varieties against chocolate spot (botrytis fabae) in north gondar, ethiopia. african journal of agricultural research, 10(30): 2984–88. witcombet, j.r., joshi, a., joshi, k .d. and sthapit, r. 1996. farmer participatory crop improvement. i. varietal selection and breeding methods and their impact on biodiversity. expl agric. 32: 445–60. wondimu bekele. 2016. participatory variety selection of faba bean for yield components and yield at highlands of west hararghe, eastern ethiopia. international journal of plant breeding and crop science, 3(1): 99–102. yirga and zinabu east african journal of sciences volume 13 (1) 7-14 14 east african journal of sciences (2018) volume 12 (1) 29-40 _____________________________________________________________ licensed under a creative commons *corresponding author. e-mail: beyeneshzm@yahoo.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) effect of mineral fertilizer, farmyard manure, and compost on yield of bread wheat and selected soil chemical properties in enderta district, tigray regional state, northern ethiopia beyenesh zemichael1* and nigussie dechassa2 1 tigray agricultural research institute, mekelle agricultural research centre, p.o. box 498, mekelle, tigray, ethiopia 2haramaya university, college of agriculture and environmental sciences, p. o. box 138, dire dawa, ethiopia abstract: soil nutrient depletion as a result of continuous cultivation of the land without adequate addition of external fertilizer inputs is one of the major problems that constrain the yield of bread wheat and sustainable productivity of the soil in tigray regional state. a field experiment was conducted to elucidate the effect of mineral nitrogen and phosphorus fertilizer (np), farmyard manure (fym), and compost on the productivity of bread wheat and selected soil chemical properties. the treatments consisted of three bread wheat varieties (kakaba, paven 76, and mekelle i) and eight fertilizer combinations [control (0, 0), blanket recommended np fertilizer (rnp) (41 kg n ha-1 + 46 kg p2o5 ha-1), 10 t ha-1 fym, ½ of rnp (20.5 kg n ha-1 + 23 kg p2o5 ha-1) + 10 t ha-1 fym, ½rnp (20.5 kg n ha-1 + 23 kg p2o5 ha-1) + 5 t fym ha-1, 7 t compost ha-1, ½ rnp (20.5 kg n ha-1 + 23 kg p2o5 ha-1) + 7 t compost ha-1, and ½ rnp (20.5 kg n ha-1 + 23 kg p2o5 ha-1) + 3.5 t compost ha-1]. the experiment was laid out as a randomized complete block design in a factorial arrangement and replicated three times per treatment. data were collected on yield and yield components of the crop and selected soil chemical properties, namely, contents of soil organic carbon (oc), available phosphorus (p), total nitrogen (tn), cation exchange capacity (cec), soil reaction (ph), and electric conductivity (ec). the results revealed that the yield and yield components of wheat significantly (p ≤ 0.01) responded to application of the fertilizers. combined application of 10 or 5.0 t ha-1 fym with half of the recommended mineral nitrogen and phosphorus fertilizer (i.e., 20.5 kg n + 23 kg p2o5 ha-1) increased grain yield of the crop by 185 and 170%, respectively, over the control treatment. similarly, combined application of 7.0 or 3.5 t ha-1 compost with half of the recommended mineral nitrogen and phosphorus fertilizer (20.5 kg n + 23 kg p2o5 ha-1) increased grain yield significantly by 159 and 148%, respectively, over the control treatment. the highest net benefits of 37290 etb, 33002 etb, and 30835 etb ha-1 with acceptable marginal rates of return were obtained in response to applying half of the blanket recommended miner np fertilizer (½ rnp) ha-1 + 5 t fym ha-1 to kakaba, mekelle i, and paven 76, followed by application of the full blanket recommended np fertilizer (rnp) ha-1 and ½ rnp ha-1+ 5 t ha-1 compost. it is, thus, concluded that combined application of half of the blanket recommended np fertilizer (20.5 kg n + 23 kg p2o5 ha-1) with 5 t fym ha-1or with 3.5 t ha-1 compost led to the most economically optimum bread wheat yield as well as improved soil physico-chemical properties for sustainable production of the crop in the future. analysis of the selected soil chemical properties at harvest indicated that, compared to the available phosphorus and total nitrogen contents of the soil in plots to which no any fertilizer was applied (control treatment), the total nitrogen and phosphorus contents of the soil to which 10 t ha-1 fym and 7 t ha-1 compost were applied increased by about 100% whereas that of organic matter increased by about 300%. the results indicate that the soils of the study area are deficient not only in mineral nutrients such as nitrogen and phosphorus but also in soil organic carbon and its constituents that are important to maintain soil quality and health. this implies that there is a need for judicious soil ameliorative measures using both mineral and organic fertilizers to enhance productivity of crops in the region. keywords: blanket recommended np (rnp) fertilizer; compost; economic analysis; farmyard manure; np fertilizer; bread wheat variety; triticum aestivum l; yield 1. introduction wheat (triticum aestivum l.) is widely cultivated in mid and highland areas of tigray, northern ethiopia. bread wheat ranks third in production area following sorghum and tef with over 105,308 hectares (ha) with a total production of about 200169 tons (csa, 2013). bread wheat production has steadily increased over the last decade, which could be attributed to both expansion of production area and improvement in yield (csa, 2013). despite its relatively large area coverage in the country, yields of the crop are still low. the average grain yield of bread wheat in tigray regional state amounts to 1.94 t ha-1 (mesay et al., 2012), which is less than the national average yield of 2.4 t ha-1. still the national average yield of wheat in ethiopia is 13% lower than the african average wheat yield and 32% beyenesh and nigussie east african journal of sciences volume 12 (1) 29-40 30 lower than the world’s average yield (gashaw et al., 2014). therefore, what production is insufficient to meet the increasing demand for food for the everincreasing population (gain, 2014). though numerous factors are responsible for low crop yields, low soil fertility is a major problem that affects crop production in the ethiopian highlands. the decline in crop yields in the country primarily results from loss of nutrients through soil erosion, cultivation of marginal lands, continuous cultivation with limited external inputs, less manure use and overgrazing (atakilte et al., 2006). these problems result in reduced soil organic matter which is lower than 1% (fassil and yamoah, 2009). in addition, organic amendments are insufficient to offset the rapid loss in soil organic matter (som), leading to unsustainable farming system. this situation is considered to be a major threat to food security and natural resource conservation in ethiopia. soil nutrient replenishment is, therefore, a prerequisite to halting soil fertility decline. this may be accomplished by the application of mineral and organic fertilizers (wakene et al., 2004). in ethiopia, the rates of application of mineral n and p fertilizer are generally low due to steep prices and untimely availability of the fertilizer input (dercon and christiaensen, 2007; kassie et al., 2008) and fear of burning effect by mineral fertilizers in case of moisture inadequacy in the soil or erratic rainfall after application of fertilizer (hailu, 2010). one of the possible options to reduce the use of mineral fertilizer without nitrogen deficiency could be recycling of organic wastes. some studies in ethiopia have shown the importance of organic matter (om) in improving soil productivity (wakene et al., 2001). further, the mobilization of nutrients through som decomposition makes an important and, in some cases, a sole contribution to maintaining or enhancing soil fertility in areas where mineral fertilizers are scarce (assefa, 2008). likewise, the use of om increases the capacity of the soil for moisture retention which enables the crop to access water even during the dry spells (balesh et al., 2007; edwards et al., 2007). thus, the use of organic fertilizer is important for the region like tigray, where crop productivity is severely affected by erratic rainfall. but the availability of organic fertilizer as nutrient sources is limited by their competing end-uses such as fuel wood, construction, feed as well as scarcity of labor required to collect and apply it to farm fields. in addition, organic residues most available to farmers have low nutrient concentrations or need prolonged time to release nutrients for plant uptake (godara et al., 2012). hence, organic resources used alone offer insufficient nutrients to sustain crop yields and build soil fertility. yet, they will continue to be a critical nutrient source as smallholder farmers in the tropics are unable to afford mineral fertilizers because of escalating fertilizer prices (palm, 2001). high prices of mineral fertilizers together with the challenges of limited supply of organic inputs, therefore, calls for combined use of organic and mineral sources of plant nutrients (devi et al., 2007, wakene et al., 2007). several studies in the country reported that integrating organic and inorganic fertilizers improved soil fertility and productivity (edwards et al., 2007, getachew and chilot, 2009, dejene et al., 2010, abay and tesfaye, 2012, medhn et al., 2013). while numerous studies have been conducted in tigray to examine the effect of organic and inorganic fertilizers, no research has so far been done in the study area to elucidate the influence of applying mineral np and organic fertilizers (both fym and compost) on the productivity of bread wheat and physico-chemical properties of the soils. this research was, therefore, aimed at studying the effect of mineral and organic fertilizers on the productivity of bread wheat and its concomitant effect on selected physicochemical properties of the soil. 2. materials and methods 2.1. description of the experimental site the study was conducted in enderta district. geographically, the site is located in the southeast of tigray at 130 5‘n latitude, 390 5‘e longitudes and at an altitude of 1970 meters above sea level. the long-term (1995-2013) average annual precipitation was 522 mm while the total rainfall of the 2013 growing season was 398 mm of which 317 mm was received during the main cropping season which was below the long term average. in 2014, the annual rainfall of the season was 782 mm of which 537 mm was received during the growing season (fig 1). the study site has a mono-modal rainfall pattern with an extended rainy season from march to november with the peak occurring in the month of august. the main rainy season is between june and september, during which about 83% of the annual rainfall occurs. the area is characterized by heavy and erratic rainfall distribution. the area has mixed farming system (crop and livestock) with crop dominance. the dominant crops growing around the experimental area are wheat (triticum aestivum l.), maize (zea mays l.), barley (hordeum vulgare), tef (eragrostis tef) and some legumes and vegetable crops. the soil of the experimental site is vertisol with a clay content of 48% (rowell, 1994). according to the rating of tekalign (1991), the soil reaction is neutral (7.23), organic carbon content is low (1.31%); and the total nitrogen content is very low (0.02%). according to the rating of cottenie (1980), the available phosphorus content is low (5.33 ppm). based on the rating of hazelton and murphy (2007), the cec of the soil is high (37 cmol(+) kg-1 soil). beyenesh and nigussie effect of mineral fertilizers, farmyard manure, and compost on yield and soil properties 31 figure 1. monthly total rainfall (mm) and monthly average air temperature ranges (t0), in 2013 and 2014 cropping seasons. source; mekelle research meteorological service. 2.2. planting material three bread wheat varieties, namely, kakaba, mekelle i, and paven 76 were used as test crops. kakaba was released by kulumsa agricultural research centre (karc) in 2005. it needs >500 mm rainfall for optimum growth and is adapted to altitudes ranging between 2000 and 2900 meters above sea level. the variety requires 90-120 days to reach maturity. the average plant height of kakaba is 89-95 m. on-station grain yield of kakaba ranges between 4.0 to 5.5 t ha-1 whereas its on-farm grain yield ranges between 3.0 to 4.0 t ha-1. mekelle i was released by mekelle agricultural research centre (marc) in 2011. it is a semi-dwarf variety known for drought tolerance, but performs better under good rainfall conditions. it requires between 300 and 500 mm rainfall for optimum growth and is adapted to altitudes ranging between 1980 and 2500 meters above sea level. the variety needs 90-95 days to reach maturity (hintsa et al., 2011). the average height of mekelle i plants ranges between 77 and 79 m. on-station grain yield of mekelle i ranges between 3.0 and 3.5 ha-1 whereas its on-farm grain yield ranges between 2.2 and 2.7 t ha-1. paven 76 was released by kulumsa agricultural research centre (karc) in 1982. it needs >500 mm rainfall for optimum growth and is adapted to grow at altitudes ranging between 750 and 2500 meters above sea level. the variety needs between 120 and 135 days to mature. on-station grain yield of paven 76 ranges between 4.0 to 4.5 t ha-1 whereas its on-farm grain yield ranges between 3.5 to 4.0 t ha-1. the three varieties were selected based on differences in maturity time, yield potential, adaptability, and the fact that they are commonly cultivated by smallholder farmers in the region. 2.2. treatments and experimental design the treatments consisted of eight fertilizer combinations [control (no fertilizer application), blanket recommended np fertilizer (rnp): 100 kg ha-1 dap plus 50 kg ha-1 urea (41 kg n + 46 kg p2o5 ha-1), 10 t ha-1 fym, ½ rnp fertilizer (20.5 kg n ha-1 + 23 kg p2o5 ha-1) + 10 t fym ha-1, ½ rnp fertilizer (20.5 kg n ha-1 + 23 kg p2o5 ha-1) + 5 t fym ha-1, 7 t ha-1 compost alone, ½ rnp fertilizer (20.5 kg n ha-1 + 23 kg p2o5 ha-1) + 7 t ha-1 compost, ½np fertilizer (20.5 kg n ha-1 + 23 kg p2o5 ha-1) + 3.5 t ha-1 compost and three bread wheat varieties [mekelle i, kakaba, and paven76 ]. the experiment was laid out as a randomized complete block design (rcbd) in a factorial arrangement and replicated three times per treatment. 2.3. fertilizer material farmyard manure (fym): well-decomposed fym (15% moisture content) was collected from mekelle livestock research center. compost: the compost was made from fym, crop residues, household refuse, ash, weeds and grasses on a farmer’s field and used as fertilizer. the organic materials used for composting were collected depending on their availability in the study area. for a quick start of microbial activities, all sides of the walls of the composting pit were painted with semi-liquid mixture of dung, water, and animal urine. about 15 cm height layer of the mixed dry and green materials were put first and a mixture of different animal manure with about 5 cm height was added. water was then sprinkled to wet the dry matter. again dung slurry was spread. lastly some fertile soil was added over the whole layer. this process was repeated four times to fill a1 m x 1.5 m x 1.5 m pit. lastly, the heap was covered by a mixture of soil and dung and wide leaves were used as cover to protect the compost from sun and wind. the compost was turned over after one month and the moisture was again maintained. it was turned over for the second time. the compost matured in a period of three months (hailu, 2010). mineral fertilizer: urea [co (nh2)2] (46% n) and triple super phosphate (tsp) [ca (h2po4)2] (20% p) were used as sources of nitrogen and phosphorus, respectively. 2.3. experimental procedure 2.3.1. soil sampling and analysis prior to planting, surface soil samples (0–20 cm), from twelve spots across the experimental field, were collected, composited, and analyzed for soil physicochemical properties following the standard laboratory procedures. the n and p contents of fym and compost used in the experiment were also determined in the laboratory (table 1). 2.3.2. crop management the experimental field was ploughed three times using ox-driven implements followed by manual seed-bed preparation. the compost and farmyard manure were applied to the soil one month before planting. the application was done by mixing the fym and compost in the upper 15beyenesh and nigussie east african journal of sciences volume 12 (1) 29-40 32 20 cm of the soil layer. the rates were identified considering the highest and the lowest application rates of fym and compost as described by edward (2007), dejene et al. (2010), and hailu (2010). the blanket recommended fertilizer rate of 41 kg n + 46 kg p2o5 ha-1 was used. all the mineral p and half of the n fertilizer were applied at planting. the remaining half of the mineral n fertilizer was applied at the tillering stage of growth. seeds of the bread wheat varieties were hand-drilled at the rate of 150 kg ha-1 on 19 and 12 july 2013 and 2014 cropping seasons, respectively. the size of each plot was 3 m x 2 m (6 m2). weeds were removed by hand two times 30 and 55 days after crop emergence. harvesting was done manually using hand sickles. table 1. chemical composition of fym and compost used in the experiment. year farmyard manure compost ph tn (%) p (ppm) om (%) ph tn (%) p (ppm) om (%) 2013 8.14 1.49 0.89 34.60 7.50 1.02 0.79 25.20 2014 8.23 1.75 0.95 36.66 7.60 1.49 0.82 22.79 average 8.18 1.62 0.92 35.63 7.55 1.26 0.805 23.99 note: om = organic matter; tn = total nitrogen; p = phosphorus 2.4. data collection and measurement data on grain and biomass yields per plot were collected from the middle 6 rows. aboveground biomass was sunand air-dried for three days. the grain yield (kg ha-1) was determined after threshing the sun-dried plants harvested from each net plot area and the yield was adjusted to 12.5% moisture content. harvest index (hi) was calculated as the ratio of grain to the above ground dry biomass yield. kernels spike-1 (nkps) was determined from 10 randomly sampled plants per plot at physiological maturity. thousand kernel weight was determined and partial cost benefit analysis associated with the treatments was conducted (cimmyt, 1988). economic analysis was done using the prevailing average market prices for inputs at planting and for outputs at the time of crop harvest. the average local market price of wheat was 11.29 birr (etb) kg-1; that of the straw was 0.68 birr kg-1. the cost of farmyard manure was 225 birr t-1. the recommended dose of the mineral np fertilizers was 19.30 birr kg-1. the cost of compost and farmyard manure was 166 birr t-1. transportation and application cost of compost and farmyard manure was 10 birr/100 kg. the net benefit (nb) was calculated as the difference between the gross benefit (gb) and the total cost that varied (tcv). actual grain and straw yields were readjusted downward by 10% to reflect the difference between the experimental yield and the yield farmers would expect to get from the same treatment. all costs and benefits were based on the average of the two-year yields. percent marginal rate of return (mrr) was calculated as changes in nb (raised benefit) divided by changes in cost (raised cost). 2.5. statistical analysis all data were analyzed following statistical procedures of sas version 9.2. whenever treatment effects were significant, the means were separated using the least significant difference (lsd) test at 5% level of significance 3. results 3.1. soil chemical properties after harvest the results showed that application of mineral and organic fertilizers significantly increased the contents of soil organic matter (som), phosphorus (p), and total n (tn) of the soil in both cropping years. in the 2013 cropping season, in response to the application of 10 t ha-1 fym and 7 t compost ha-1, the total nitrogen and available phosphorus contents of the soil increased by about two-fold (100%) whereas that of organic matter increased by about three-fold (300%), compared to the plots to which did not receive any fertilizer (control treatment). similarly, in the 2014 cropping season, the total nitrogen and organic matter content of plots treated with 10 t ha-1 fym and 7 t compost ha-1 increased by about two-fold (by 100%) whereas the available phosphorus content increased by about halffold (50%) (table 3). in response to the application of both organic and mineral fertilizers, the ph of the soil also increased slightly whereas the ec and cec of the soil increased significantly (table 4). beyenesh and nigussie effect of mineral fertilizers, farmyard manure, and compost on yield and soil properties 33 table 3. effect of applying organic and mineral fertilizers on some soil chemical properties of the experimental soil after harvest during the 2012 and 2013 main cropping season in enderta district, tigray regional state, ethiopia. soil chemical property treatment 2013 2014 tn% p (ppm) om% tn% p(ppm) om% recommended np (41kg n + 46 kg p2o5 ha-1 0.17b 5.13d 1.22b 0.19b 6.19b 2.12ab 10 t fym ha-1 0.16b 5.76bcd 1.38ab 0.19b 6.35ab 2.10ab 20.5 kg n + 23 kg p2o5 ha-1 + 10 t fym ha-1 0.20a 7.30a 1.62a 0.22a 6.71ab 2.19ab 20.5 kg n + 23 kg p2o5 ha-1 + 5 t fym ha-1 0.18ab 7.21abc 1.56a 0.20ab 7.12a 2.15ab 7 t compost ha-1 0.16b 5.07d 1.48ab 0.18b 7.00ab 2.07b 20.5 kg n + 23 kg p2o5 ha-1 + 7 t compost ha-1 0.18ab 7.26ab 1.57a 0.21ab 6.35ab 2.27a 20.5 kg n + 23 kg p2o5 ha-1 + 3,5 t compost ha-1 0.18ab 5.73cd 1.39ab 0.20ab 6.88ab 2.27ab control (unfertilized) 0.08c 2.55e 0.43c 0.11c 5.14c 0.89c lsd(0.05) 0.03 1.19 0.28 0.03 0.86 0.19 cv% 16.02 27.62 22.47 14.02 14.09 10.22 note: means followed by the same letter within a column are not significantly different at 5% level of significance according to the lsd fishers protected test; tn% = total nitrogen; avp = available phosphorus; om = organic matte table 4. effect of organic and mineral fertilizers on ph, electrical conductivity (ec) and cation exchange capacity (cec) of the soil after harvest of bread wheat in enderta district, tigray regional state, ethiopia. 2013 2014 treatment ph ec(ds m-1) cec* ph ec(ds m-1) cec* blanket recommended np rate (41kg n + 46 kg p2o5 ha-1) 7.28bc 0.16c 38.51b 7.16b 0.19c 44.29b 10 ton ha-1farmyard manure (fym) 7.30bc 0.17ab 42.58a 7.17b 0.20bc 48.36a 20.5 kg n + 23 kg p2o5 ha-1 + 10 ton ha-1fym 7.45ab 0.15c 36.96b 7.19b 0.25a 42.74b 20.5 kg n + 23 kg p2o5 ha-1 + 5.0 ton ha-1fym 7.40abc 0.16bc 37.48b 7.27b 0.24a 43.26b 7.0 ton compost ha-1 7.37bc 0.19a 38.17b 7.29b 0.22ab 43.95b 20.5 kg n + 23 kg p2o5 ha-1 + 7.0 ton ha-1compost 7.60a 0.15c 38.61b 7.69a 0.23ab 44.39b 20.5 kg n + 23 kg p2o5 ha-1 + 3,5 ton ha-1compost 7.34bc 0.17abc 37.85b 7.25b 0.23ab 43.26b control (unfertilized) 7.20c 0.11d 26.03c 7.13b 0.16d 32.03c lsd(0.05) 0.20 0.02 3.61 0.20 0.03 3.55 cv% 2.94 13.26 10.35 2.92 14.57 8.78 note: * = cec cmol(+) kg soil-1; means followed by the same letter within a column are not significantly different at 5% level of significance according to the lsd fishers protected test 3.2. aboveground dry biomass yield total aboveground dry biomass yield was significantly (p < 0.01) influenced by the main effects of variety, fertilizer, year, and by the interaction of year and fertilizer as well as variety. in 2013, the total aboveground dry biomass yield increased by about 124% in response to the application of mineral np fertilizers together with 10 t ha-1 fym while in 2014 the increase was, higher, i.e., 153%. combining half of the blanket recommended np fertilizer (20.5 kg n + 23 kg p2o5 ha-1) plus 10 t ha-1 fym, 5 t ha-1 fym, 7 t ha-1 compost, and 3.5 t ha-1 compost increased the aboveground dry biomass yield by 27%, 19%, and 14% during the 2013 cropping season and by 15%, 9 % and 7% in 2014 over the full dose of the blanket recommended np fertilizer (41kg n + 46 kg p2o5 ha1), respectively (table 5). 3.3. grain yield grain yield of the crop responded significantly to the fertilizers applied, variety, and year, but not to the interaction effects of any of the three factors (table 6). combining half dose of the blanket recommended mineral np fertilizer (20.5 kg n + 23 kg p2o5 ha-1) with 10 and 5.0 t fym ha-1 led to the production of the highest grain yields, which are in statistical parity. in general, combining half of the blanket recommended np fertilizer with 10 and 5 t ha-1 fym, and 7 and 3.5 t ha-1 compost increased wheat grain yield by 185%, 170%, 160% and 149%, respectively, over the control treatment. the increments in grain yield obtained in response to the application of the aforementioned fertilizer combinations also led to significant grain yield increments of 19, 25, 14, and 9.0%, respectively, over the grain yield obtained in response to application of full dose of the blanket recommended mineral np fertilizer. the respective increments in grain yield over the grain yield obtained in response to the application of full dose of fym (10 t ha-1) were 36, 29, 24, and 19%. similarly, the highest grain yields obtained in response to the combined application of half dose of beyenesh and nigussie east african journal of sciences volume 12 (1) 29-40 34 mineral np fertilizers with 10 t fym and 5 t fym ha-1, resulted in the production of about twice as much wheat grain yield as the average wheat grain yield obtained in the region of the study area (additional increments of 80 and 90%, respectively), which is 1.4 t ha-1. similarly, the wheat grain yields obtained at the aforementioned combined application of the fertilizers resulted in increments of about 45 and 53%, respectively, over the national bread wheat grain yield, which is 2.4 t ha-1. table 5. interaction effects of year by fertilizer and variety on total biomass yield of bread wheat in 2013 and 2014 cropping seasons in enderta district, tigray regional state. fertilizer rate and variety above ground biomass yield (kg ha-1) 2013 2014 fertilizer 41 kg n + 46 kg p2o5 ha-1) 6771.7gh 8076.6cde 10 ton ha-1fym 6225.7hi 7776.6def 20.5 kg n + 23 kg p2o5 ha-1 + 10 t ha-1fym 8618.0abc 9342.6a 20.5 kg n + 23 kg p2o5 ha-1 + 5 t ha-1fym 8084.6cde 8834.5ab 7 t compost ha-1 5680.6i 7495.2efg 20.5 kg n + 23 kg p2o5 ha-1 + 7 t ha-1compost 7730.9def 8664.8abc 20.5 kg n + 23 kg p2o5 ha-1 + 3.5 t ha-1compost 7174.3efg 8416.9bcd control (unfertilized) 3845.6j 3681.0j lsd (0.05) 736.22 variety mekelle i 6774.4c 7883.7b paven 76 6666.5c 7092.2c kakaba 6858.4c 8382.2a lsd (0.05) 450.84 cv% 10.80 note: means followed by the same letter within a column and row of each factor are not significantly different at 5% level of significance 3.4. straw yield straw yield of the crop responded significantly (p < 0.01) to the fertilizers applied, variety, year and interaction of variety by year (table 6). application of np, organic fertilizers and their combinations significantly increased the straw yield. application of half of the blanket recommended np fertilizers combined with 10, 5 t ha-1 fym, and 7 t compost ha-1 increased the straw yield over the control treatment by about 142, 100, and 96% respectively. straw yield of bread wheat was also significantly influenced by the interaction of variety and year in which straw yields were higher for all varieties in 2014 than in 2013 (table 6). 3.5. harvest index harvest index significantly varied in response to application of the fertilizers, variety, and year and due to the interaction of year and variety (table 6). it ranged from 34.25% to 41.06%. the highest harvest indices were recorded for all combined application rates of the three fertilizers whereas the lowest were recorded for the application of lone full dose of the blanket recommended mineral np fertilizers (41 kg n + 46 kg p2o5 ha-1), lone full dose of fym (10 t ha-1), and the control treatments. for the bread wheat varieties, the harvest indices ranged from 42% for kakaba in 2014 to 36% for paven 76 in 2013 (table 7). however, the harvest index of kakaba was significantly higher than the harvest indices of the two other bread wheat varieties (tables 6 and 7). 3.6. partial budget analysis the treatment having mrr below 100% was considered low and unacceptable to farmers thus eliminated (cimmyt, 1988). this was because such a return would not offset the cost of capital and other inputs while still giving an attractive profit margin to serve as an incentive. the economic analysis revealed that the highest net return with acceptable marginal rates of return of 37290 etb, 33002 etb, and 30835 etb ha-1 were obtained in response to the application of half of the blanket recommended rate of np fertilizer (20.5 kg n + 23 kg p2o5 ha-1)+ 5.0t fym ha-1. the highest net returns were recorded at the aforementioned rate of fertilizer for the varieties kakaba, mekelle i, and paven 76, in a decreasing order as stated here (table 8). beyenesh and nigussie effect of mineral fertilizers, farmyard manure, and compost on yield and soil properties 35 table 6. mean grain yield, straw yield, and harvest index (hi) of bread wheat varieties as influenced by application of mineral and organic fertilizers, variety and year of cultivation in the 2013 and 2014 main cropping seasons in enderta, tigray regional state, ethiopia. fertilizer rate nkps (no.) tkw (g) grain yield (kg ha-1) straw yield (kg ha-1) hi% 41 kg n + 46 kg p2o5 ha-1 36.58c 36.82bc 2928.70c 4495.50bcd 39.20b 10 t fym ha-1 35.45c 35.31bc 2700.00de 4301.20cd 38.35b 20.5 kg n + 23 kg p2o5 ha-1 + 10 t fym ha-1 41.84a 39.97a 3678.50a 5301.80a 40.94a 20.5 kg n + 23 kg p2o5 ha-1 + 5.0 t fym ha-1 41.63a 38.96ab 3486.6ab 4972.90ab 41.06a 7.0 t compost ha-1 34.58c 34.37c 2547.60e 4040.30d 40.58a 20.5 kg n + 23 kg p2o5 ha-1 + 7.0 t compost ha-1 40.49ab 40.50a 3346.5bc 4851.30ab 40.76a 20.5 kg n + 23 kg p2o5 ha-1 + 3.5 t compost ha-1 38.87b 38.64ab 3206.00c 4589.60bc 41.07a control (unfertilized) 28.67d 28.37d 1289.00f 2474.30e 34.25c lsd (0.05) 2.18 2.78 248.90 492.99 1.54 variety mekelle1 37.32b 36.07b 2868.63b 4460.44a 38.67b paven 76 35.20c 35.56b 2650.32c 4229.00b 38.01b kakaba 39.27a 38.24a 3174.65a 4445.60ab 41.14a lsd (0.05) 1.33 1.70 152.42 231.86 0.94 year 2013 35.87b 33.99b 2592.75a 4173.68b 38.09b 2014 38.66a 39.26a 3202.97b 4583.06a 40.46a lsd(0.05) 1.09 1.39 124.45 188.00 0.77 cv% 8.86 11.48 23.54 12.99 6.22 note: means of the same parameter in a column followed by the same letter are not significantly different at p = 0.05 according to lsd fishers protected test. nkps = number of kernels per spike, tkw = thousand kernel weight hi = harvest index table 7. interaction effect of variety and year on harvest index and straw yield of bread wheat in 2013 and 2014 main cropping seasons in enderta, tigray regional state, ethiopia. variety straw yield (kg ha-1) harvest index (%) 2013 2014 2013 2014 mekelle i 4230.41b 4690.53a 37.35c 40.00b kakaba 4065.55b 4825.83a 40.61ab 41.67a paven 76 4225.20b 4232.90b 36.31c 39.71b lsd(0.05) 325.12 1.33 cv% 12.99 5.92 note: means in a column followed by the same letter are not significantly different at 5% level of significance according to lsd fishers protected test 4. discussion the increase in soil organic matter, total nitrogen, and available phosphorus observed in this study in response to the application of fym and compost are in line with the findings of aziz et al. (2010), dinesh et al. (2012) and kwadwo et al. (2015) who reported enhanced contents of soil organic matter and plant available nutrients in response to the application of organic fertilizers. similarly, these results are in agreement with that of wondimu et al. (2006) who reported that fym application increased soil organic matter over the control treatment and improved soil fertility status at sirinka agricultural research centre in northern ethiopia. the enhanced crop growth and productivity due to the application of integrated organic manure and mineral fertilizer may be attributed to improved soil physical conditions, enhanced soil fertility and gradual release of plant nutrients and increased nutrient uptake by the plant to support growth. similar results were also reported by afifi et al. (2003), matsi et al. (2003), and rehman and khalil (2008) who obtained higher aboveground biomass yield from the application of organic manure and mineral fertilizer, which could be attributed to improved root growth and increased uptake of nutrients favoring better growth and delayed senescence of leaves of the crop. beyenesh and nigussie east african journal of sciences volume 12 (1) 29-40 36 table 8. estimated marginal rate of return (%) for mineral and organic fertilizer treatments on bread wheat during the 2013 and 2014 cropping seasons in enderta district, tigray regional state, ethiopia. note: rnp = recommended fertilizer rate; tvc = total variable cost; mrr = marginal rate of return increase in total aboveground biomass and grain yields in response to application of the mineral and organic fertilizers could be attributed to enhanced uptake of nutrients and water by the plants as a result of improved availability in the soil. this result is consistent with that of sarwar et al. (2008), who reported enhanced growth and yield of rice in response to application of compost the significantly higher yield and dry biomass yield of kakaba in comparison to the other two bread wheat varieties could be attributed to the genetic constitution of the variety as indicated by sharshar and said (2000). the other possibility may have been differential uptake of nutrients by the varieties. kakaba may have increased its total aboveground biomass yield through more uptake and efficient utilization of the available nutrient (data not shown). the difference in the grain yield of wheat varieties might be due to the differences in their yield components like spike length, kernels per spike, number of effective tillers produced per plant and harvest index that may have contributed to the highest grain yield of the former. corroborating this result, iftikhar et al. (2002) and jemal et al. (2015) showed enhanced grain production of wheat varieties due to better production of fertile tillers, number of grains per spike, and maximum 1000-grain weight. it is obvious that high yielding wheat varieties demand ample nutrient supply to produce maximum grain yield (ali and yasin, 1991). in the same way, dalrymple (1986) reported that semi-dwarf wheat varieties were shown to attain increased yields through more efficient utilization of assimilates associated with crop lodging. furthermore, varying yields between the growing seasons might be attributed to differences in rainfall variability in which the mount (522 mm) and distribution of rainfall in 2014 was apparently more adequate than the one that fell in the 2013 cropping season which amounted to 398 mm, and was less by about 24% than the rainfall that was received in 2014. thus, the observed increase in grain yield components in the 2014 growing season could be ascribed to enhanced water and nutrient availability in the soil, which may have concomitantly improved uptake of nutrients by the wheat plants, thereby leading to enhanced production and translocation of dry matter contents from source to sink (ebaid et al., 2007). similar results were also reported by dejene et al. (2010) in which grain yield of tef was significantly influenced by fertilizer type and year. on the other hand, the low biological yields of the crop plant in the 2013 cropping season may be attributed to the relatively lower amount of rainfall received than the amount received in the 2014 cropping season. consistent with this suggestion, muurinen et al. (2007) also indicated that seasonal differences in rainfall accounted for year x genotype and year x n rate interactions. likewise, the varying grain yields between the years could also be attributed to the varying dry matter production contributed by higher nutrient uptake (data not shown) for increased metabolic activity. treatment tcv (etb ha-1) net benefit (etb ha-1) raised benefit (etb ha-1) raised cost (etb ha-1) mrr% variety mekelle i control(check) 0.00 14564.04 rnp (41 kg n + 46 kg p2o5 ha-1) 2130.15 30242.05 15678.01 2130.15 736% ½ rnp + 3.5 compost t ha-1 2146.32 31040.20 798.15 16.17 4936% ½ rnp + 5 t fym ha-1 2790.07 33002.07 1961.87 643.75 305% ½ rnp + 10 t fym ha-1 4415.07 33838.12 836.05 1625.00 51% variety kakaba control(check) 0.00 15422.41 rnp (41 kg n + 46 kg p2o5 ha-1) 2130.15 30770.98 15348.57 2130.15 721% ½ rnp + 3.5 compost t ha-1 2146.32 32708.30 1937.32 16.17 11981% ½ rnp + 5 t fym ha-1 2790.07 37290.80 4582.50 643.75 712% ½ rnp + 10 t fym ha-1 4415.07 37134.16 1625.00 1625.00 100% variety paven76 control(check) 0.00 12367.32 rnp (41 kg n + 46 kg p2o5 ha-1) 2130.15 26720.23 14352.91 2130.15 674% ½ rnp + 3.5 compost t ha-1 2146.32 27288.20 567.97 16.17 3512% ½ rnp + 5 t fym ha-1 2790.07 30835.38 3547.18 643.75 551% ½ rnp + 10 t fym ha-1 4415.07 31416.23 580.85 1625.00 36% beyenesh and nigussie effect of mineral fertilizers, farmyard manure, and compost on yield and soil properties 37 similar observations were also made by alam (2007) where varieties responded differently to differences in nutrient supplies in the soil. on the other hand, sharshar and said (2000) reported that different varieties responded differently to their genotypic characters, input requirements, growth process and the prevailing environment during the growing season. a similar result was also reported by alam (2007). the increase in grain yield of wheat in response to combined application of mineral fertilizers either with fym or compost might be attributed to possible improvement in moisture retention capacity, soil physical properties, enhanced soil fertility and better utilization of nutrients (edward, 2007; tayebeh et al., 2010; chuan et al., 2013; assefa, 2015; tewodros and belay, 2015). the beneficial effect of organic manure on yield may be due to the increased organic matter content of the soil (wilkinson, 1979) and improvement in the soil structure conditions, which encourages the plant to have good root development by improving the aeration and moisture holding capacity of the soil (arisha et al., 2003). this suggestion is concurrent with the results of murage et al. (2000) who reported that soil organic matter is a surrogate for total soil nitrogen. sharma et al. (1990) also reported that the application of manure made the soil more porous and pulverized it which allows better root growth and development and significantly increased the root cec at each stage of growth. besides, compost not only releases nutrients slowly but also prevents losses of mineral fertilizers through denitrification, volatilization and leaching by binding to nutrients and releasing them with the passage of time, thereby improving nutrient uptake by plants and crop yields (arshad et al., 2004). increased grain yields in response to the integrated use of organic and mineral fertilizer as opposed to their sole application were reported by various researchers (getachew and taye , 2005; våje, 2007; bandyopadhyay et al., 2009, dejene et al., 2010). the increased yield attributes might be due to induced cell division, expansion of cell wall, meristematic activity, photosynthetic efficiency and regulation of water intake into the cells, resulting in the enhancement of yield parameters (hidayatullah et al., 2013; sharma et al., 2013). in addition, it is evident from the results obtained in this experiment that combining mineral fertilizer with fym was more productive than combining with compost. this might be attributed to the difference in nutrient concentration of the fym and compost used in the experiment, in which n, p and organic matter contents in farmyard manure were higher than the compost which may have induced better growth as reported by chong (2005) and dejene et al. (2010). the increment in hi from combined fertilizer application might be attributed to greater photo assimilate production and its ultimate partitioning into grains compared to partitioning into straw. mitiku et al. (2014) also indicated that fym and inorganic np increased hi of barley. similarly, mooleki et al. (2004) reported the same on rice. thus, factors which make up grain yield such as kernel weight and kernel number have great effect on harvest index. thus, the highest harvest index of the variety kakaba may be attributed to its higher kernel weight, number of kernels and higher grain yield as compared to the other two varieties. similarly, the moisture supply during the 2014 growing season may have impacted up on higher kernel weight and kernel number as compared to 2013, which in turn may have impacted on harvest index. the highest agronomic yields, however, did not bring about the highest profit as the value of the increase in yield was not enough to compensate for the increase in costs (tvc) of the treatments. 5. conclusion the results of this study have demonstrated that applying mineral np fertilizer combined with fym and compost enhanced growth and yield of bread wheat as well as increased contents of soil organic carbon, total nitrogen, and available phosphorus. furthermore, the results have shown that variety kakaba is superior to both mekelle i and faven 76 in grain and biomass yields, indicating high potential of the variety for adoption and cultivation in the study area. concerning the fertilizer application, combined supply of the blanket recommended np fertilizer with 10 and 5 t ha-1 fym, and 7 and 3.5 t ha-1 compost increased the grain yield of the crop significantly by 185%, 170%, 160% and 149% over the control treatment, respectively. in addition, application of the aforementioned rates of combined fertilizers led to grain yield increments of 19, 25, 14, and 9.0%, respectively, over the grain yield obtained in response to application of full dose of the blanket recommended mineral np fertilizer. specifically, the cost benefit analysis also indicated that applying half of the blanket recommended mineral np fertilizer (20.5 kg n + 23 kg p2o5 ha-1) combined with 5.0 t fym ha-1 led to the production of optimum grain and straw yields. these two combined fertilizer rates resulted in the production of twice as much grain yield of the crop as the average grain yield obtained in the region (i.e., 100% increment), which is 1.4 t ha-1 and in about a 50% additional grain yield increment over the national bread wheat grain yield in the whole country, which is 2.4 t ha-1. the results of the study generally imply that optimum yields of the crop and sustainably enhanced chemical properties of the soil, namely, soil organic matter, total nitrogen, and available phosphorus are ensured not merely by application of full dose of the blanket recommended mineral np fertilizer but by combining beyenesh and nigussie east african journal of sciences volume 12 (1) 29-40 38 half of it with at least 5.0 t fym ha-1. however, dearth of fym due to scarcity and competing end-users may hinder widespread use of this fertilizer in the study area. therefore, policy makers and development agents need to focus on promoting application of organic fertilizers to crop fields as a customary practice by providing other options to replace the use of manure and crop residues as fuel wood, construction, animal feed etc. the variations in grain and strain yields across the two seasons indicated that adequate rainfall during a growing season is necessary to realize enhanced productivity of crops through fertilizer application. therefore, supplementary irrigation needs to be promoted to enhance the benefit that farmers could get from application of fertilizers. future research work has to be geared towards elucidating the effect of using varied rates of combined mineral np and organic fertilizers with different water regimes for optimization of productivity of the crop and its water and fertilizer use efficiencies in the study area. 6. acknowledgements the authors are thankful to the east africa agriculture productivity project of the ethiopian institute of agricultural research (eiar) for the financial support. the authors also thank mekelle soil 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ethiopia. biological agriculture and horticulture, 24 (3): 293-300. east african journal of sciences (2018) volume 12 (2) 127-136 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: temesgenterefeaga@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) practices and challenges of beekeeping in chiro district of west hararghe zone, eastern oromia, ethiopia temesgen terefe* haramaya university, college of agro-industry and land resources, p. o. box 226 chiro, ethiopia abstracts: ethiopia is the leading honey producer in africa and one of the ten largest honey producing countries in the world. however, low productivity and poor quality of honey and other bee products are the major constraints faced by honey producers. the exact number of people engaged in honey production and the challenges they face are not well known. lack of documented information on honey production and challenges hinders extension supports. therefore, a survey was conducted in chiro district (woreda) in 2013/2014 with the objective of eliciting information on practices of honey production, beekeeping management systems and associated challenges faced by honey producing farmers in the study area. six representative peasant associations were selected using a purposive sampling method. a total of 120 beekeepers were interviewed on major beekeeping management practice and challenges they were facing. the results were subjected to descriptive statistics using spss. of all the respondents, only 8 (6.7%) were women. a total of 863, 818 traditional beehives and 45 modern beehives were owned by the respondents. the average numbers of traditional and modern beehives owned per respondent were 6.87 and 0.38 respectively. only 58.8% of the traditional beehives and 46.7% of the modern beehives were colonized by bees while the remaining ones were empty. most (53.4%) of the respondents kept the beehives under the roof of their houses where as 30.7% kept them in the garden; 15.1% inside the house, and the 0.8% on trees. the main sources of the foundation colony were three, i.e., catching bee swarms, gift from family, and buying. the major challenges were shortage of bee colonies, escalating prices of modern hives and their accessories as well as low level of extension services. it is concluded that honey production in the study area is dominated by traditional practices, and constrained by shortage of bee colonies, inadequate farmers’ technical know-how and practical skills, high prices of modern hives and their accessories, lack of practically supported extension services on modern beekeeping technologies, incidences of pests, low participation of women, and lack of year-round availability bee forage. the results imply that the sector needs tangible supports from the extension system in terms of improved technologies as well as in building knowledge of farmers for better management of honey bees to increase productivity and income of households through honey production. keywords: absconding; bee colony; beehives; beekeeping; respondents; swarming 1. introduction of all the countries in the world, no country has a longer tradition of beekeeping than ethiopia (ayalew and gezahegn 1991). it seems as old as the history of the country and it is an integral part of the life style of the community (adebabay et al., 2008). the exact number of people engaged in the honey sub-sector in ethiopia is not well known. however, it is estimated that there exist more than 10 million bee colonies and more than one million farm households involved in beekeeping business using the traditional, intermediate and frame beehives (gidey and mekonen, 2010). ethiopia is the leading honey producing country in africa and one of the ten largest honey producing countries in the world (ayalew, 1990). the country is also one of the four largest beeswax producing countries (moard, 2012). however, low productivity and poor quality of bee products are the major economic impediments for rural beekeepers (nuru, 1999). honey bees play also a great role in pollinating plants and farmers are realizing that vegetation is a source of forage for bees. as a result, they are conscious enough to protect vegetation from destruction and propagate more plants to provide pollen and nectar for honey bees. in the process, many plants are conserved and protected from destruction (fao, 2009). holetta bee research and training center is the only institution in the country that formally undertakes adaptive and applied research on apiculture (hbrc, 2003). however, research conducted in the country so far regarding beekeeping has not elucidated the practices and challenges of beekeeping in large areas of the country that have high potential for honey production. similarly, no studies have so far been conducted to identify management practices, constrains, economic benefits, and potential of honey production in most areas of the country. in chiro district (woreda) and the highland areas of west hararghe zone, which is covered by high forest (jallo forest), and is characterized by both arable land and shrubby hills. to improve beehive management practices, researchers and experts have been giving a series of training to honey producing farmers in collaboration with haramaya university and mailto:temesgenterefeaga@gmail.com temesgen east african journal of sciences volume 12 (2) 127-136 128 non-governmental organizations. the feedback obtained from farmers has indicated existence of different challenges in the sector. however, no any systematic study has so far been carried out on honey production and associated challenges in the district. this study was, therefore, conducted to elucidate beekeeping practices and challenges as well as the degree of participation of women in production of honey bee and its products. 2. materials and methods 2.1 description of the study area chiro is one the districts (woreda) in west hararghe zone. the site is bordered on the south by kuni town, on the west by guba koricha district on the northwest by mieso district, on the north by doba district on the northeast by tulo district and on the east by the galetti river which separates it from mesela and east hararghe zone. the site is located about 325 km to the east of addis ababa along the main road to harar and dire dawa. it has a latitude and longitude of 9°05′n 40°52′e and an altitude of 1826 meters above sea level. agro-ecologically, the district is classified as highland (10%), mid-land (36%) and low land (54%) with altitude of 2300 3200, 1500 -2300 and 500-1500 meter above sea level), respectively. the district has a bimodal rainfall distribution pattern, which is most frequently erratic and its average annual rainfall is between 600 mm to700 mm. the mean annual temperature varies between 17.5°c and 27.5°c (moa, 1998). 2.2 sampling techniques, data collection and analysis the survey was conducted in six peasants associations (pa) of chiro district in west hararghe zone of ethiopia from september 2013 to june 2014 (fig. 1). both purposive and random sampling was used in this study. purposive sampling was used for selection of the six pas based on their accessibility and beekeeping potential. from each pa, 20 beekeeping farmers (a total of 120) were randomly selected from among all beekeepers and interviewed by using a pre-tested semi-structured questionnaire. the core points of the questionnaires for primary data collection on identifications of beekeeping management practices included: number of bee colonies owned, type of hives used, amount of honey harvested per colony, apiary management, bee colony placements, absconding and swarming rate, honey flow seasons and pest and predator management practices. for identification and prioritization of challenges faced by farmers in beekeeping activities, the sampled beekeepers were interviewed on natural and man-made beekeeping variables; beekeeping knowledge and related extension services, availability of bee colonies, bee predators, and availability of beekeeping equipment, drought and market. to identify women participation in beekeeping practices, women ownership of beehives and the level and type of beehive management were considered as the major variables. the number of women owning beehives from among the randomly selected 120 beekeepers was used to calculate the level of participation in beehive ownership. all sampled men respondents were interviewed on the willingness of involving women in hive managements. secondary data were also additionally collected from the district’s agricultural and rural development office. the data were analyzed using spss software and descriptive statistics. figure 1. map of the study area 3. results and discussion 3.1 household information the age group of sampled beekeepers ranged from 15 to 82 years old. accordingly, 86.1% of the respondents were between 30 to 60 years of age, while age groups of 15 to 30 and above 60 years were 8.9% and 5.1% respectively. the result showed that people in the most productive age are actively engaged in beekeeping activities with an average experience of 6.34 years. the survey result indicated that 14.2, 19.3 and 66.4 % of the respondents had above 20, between 10 and 20, and less 10 years of experiences, respectively in beekeeping. concerning the educational background of the respondents, only 4% of the beekeepers had education level of up to 12 grade whilst 32% had education level of 8th grade. about 44% of the beekeepers had only basic education (read and write) whereas 39% were illiterate (table 1). the result also indicated that 84.8% of the respondents are young beekeepers, whose age ranges between 15 to 45 years, which has the advantages to exert positive effort to integrate natural resource conservation with modern bee keeping technologies (table 1). . https://tools.wmflabs.org/geohack/geohack.php?pagename=chiro_(town)&params=9_05_n_40_52_e_region:et-or_type:city(33420) temesgen practices and challenges of beekeeping 129 table 1. household information. p ar am e te rs u se d f o r b e e k e e p e rs v ar ia b le s f re q u e n c y (n ) r e sp o n d e n ts ( % ) e d u c at io n a l le v e l illiterate 39 32.8 basic education 44 36.9 grade1-4 18 15.1 grade5-8 14 11.8 grade9-12 4 3.4 a g e g ro u p o f th e 15-30 11 9.2 30-45 90 75.6 45-60 12 10.1 >60 6 5 e x p e ri e n c e , y e ar s < 5 years 41 34.5 5-10 38 31.9 10-20 23 19.3 20-30 14 11.7 >30 3 2.5 total 119 100 3.2. type of hive owned and colony distribution fig. 2 depicts beehive ownership and bee colony distribution. a total of 863, 818, and 45 traditional and modern beehives, respectively, were owned by the 119 respondents. the average traditional and modern beehives owned per respondent was 6.87 and 0.38, respectively. 58.8% of the traditional hives and 46.7% of the modern hives were colonized bees while the remaining ones were empty. a total of 502 bee colonies with an average of 4.22 colonies per head were owned by the farmer respondents. the number of bee colonies owned in traditional hives ranged from 1 to 50 with an average of 4.04. only 15.2% of the respondents had modern hives with and without bee colonies and none of the respondents had transitional hives. the relatively lower numbers of modern hives owned that traditional hives owned could be attributed to the respondents’ inadequate level of awareness and know-how on its operation (39.7%), high costs of modern hives (40.5%), and unavailability of modern hives in the area (19.8%). out of 863 hives owned by all respondents, only 45 were modern hives of which only 21 (46.7%) were colonized by bees. accordingly, the average functional modern hives owned per respondent was 0.18. according to the respondents, about 53.3% empty modern hives lay idle for more than two years. this could be attributed to the fact that all of the modern hives were given to the farmers free of charge by different ngos without provision of any training on how to do bee keeping and with no accessories required to operate the hives. figure 2. types and number of hives with and without bees in chiro district of western hararghe zone of ethiopia 3.3 participation of women in beekeeping activities as shown in table 2, out of 119 respondents, only 8 (6.7%) were women. the result showed that all of the 8 women were widowed and acquired the hives from their husband after death. according to the response of the male beekeepers, there were a few cases whereby they accompanied their wives and/or daughters during hive management activities. most of the beehives management activities were male dominated (table 2). female participation was nil in activities like preparation of hives, installing hives, inspecting and harvesting of hive products. this could be because of traditional perception that work meant originally for male ought to be done by male only. out of the total (111) male beekeepers, only 22 (19.8%) allowed their wives to sell the harvested honey. as indicated in table. 2, cleaning apiary, preparing fresh cow dung for smearing the hives and preparation of harvesting materials were activities in which women participation was relatively better than hive ownership, inspection, and honey harvesting. all of the male (111) beekeepers reasoned out that they allow women to participate in such activities because the activities are simple to perform. the results imply the dominances of male in controlling the benefit from the sector which could reduce the interests of the women involving in the sector. temesgen east african journal of sciences volume 12 (2) 127-136 130 table 2. participation of women in hive ownership and management in sample peasant associations in chiro district of western hararghe zone of ethiopia. beehive ownership and participation in management no of respondents man woman frequency (%) frequency (%) beehive ownership traditional 119 111 93.3 8 6.7 transitional 119 0 0 0 0 modern 119 18 15.2 0 0 participation in hive management preparing beehives 111 111 100 0 0 preparing fresh cow dung for smearing hives 111 13 11.7 98 88.3 installing beehives 111 111 100 0 0 inspecting beehives 111 111 100 0 0 cleaning apiary 111 46 41.4 65 58.6 preparation of materials for honey harvesting 111 0 0 111 100 harvesting honey 111 111 100 0 0 selling honey 111 89 80.2 22 19.8 3.4 source of foundation colony and purpose of keeping bees as mentioned by the sampled respondents, the main purpose of keeping honey bees was for production of honey for household consumption and generation of income. out of the total, 89% of the respondents kept their bees for generating income while 11% kept them for home consumption. the main sources of the foundation colony were three: catching swarms, gift from family, and buying. as shown in table 3, 44.5, 41.2 and 14.3% of the respondents obtained their colonies through gift from their families, catching swarms, and buying respectively. even though obtaining colony through gift from family and catching swarms were indicated to be the highest (85.7%) source of obtaining bee colony to start beekeeping, it is not considered as a reliable source of bee colonies. this is because of the following three reasons: 1. families would not give up their strong productive bee colonies for anyone. 2. bee swarming from the traditional hives emerges accidentally and at any time of the day, most of the time when the farmers and members of their families are working in farm land or away from their homes, which would result in loss of their new swarms. the 3rd source of bee colony is buying from the other beekeepers. in the study area, bee colony buying and selling was practiced in five out of the six pas. as mentioned above, only 14.3% of the respondents have got their bee colonies through buying. however, the types of bee colony purchased were not good since almost all (99.2%) of the beekeeper sell weak colonies that proved to be non-productive. the respondents indicated another problem associated with dependence on buying bee colonies to start beekeeping. this is related to the fact that even the weakest bee colonies would not be offered for sale at a time required by buyers since most beekeeping farmers (89.2%) sell bee colonies only in case they are confronted with critical financial problems. this means bee colonies would no be on offer in the market any as needed by would-be buyers. the respondents also indicated that they buy bee colonies by trekking long distances to remote villages where beekeeping is practiced, which poses difficulty of transpiration. the price of a bee colony ranges from 1300 2000 etb with the mean price of 1385 etb. the result of the three bee colony sources in the study area indicates absence of reliable bee colony sources and bee colony multipliers. this implies that there is a high market demand for bee colonies and dearth of supply at the same time. therefore, governmental and non-governmental organizations working on beekeeping intervention should plan promotion of queen rearing and bee colony multiplication techniques. 3.5. placement of hives and beekeepers’ preference of hives as shown in table 3, the respondents placed their hives in four different places; in the house, under the roof of the house, in the garden and on trees in the garden. most (53.4%) of the respondents in the study area kept the beehives under the roofs of their houses, 30.7% kept in the garden, 15.1% kept inside houses and 0.8 % kept on trees. figure temesgen practices and challenges of beekeeping 131 table 3. sources of bee colonies to start beekeeping at sampled peasant associations in chiro district of western hararghe zone of ethiopia. name of pa source of bee colonies beekeeping total amounts gift from family catching swarm buying chirokala count 2 11 7 20 % within pa 10 55 35 100 % of total pas 1.7 9.2 5.9 16.8 arbarakate count 7 8 5 20 % within pa 35 40 25 100 % of total 5.9 6.7 4.2 16.8 arbahore count 17 2 1 20 % within pa 85 10 5 100 % of total 14.3 1.7 0.8 16.8 madicho count 10 9 0 19 % within pa 52.6 47.4 0 100 % of total 8.4 7.6 0 16 ifabas count 7 11 2 20 % within pa 35.3 55 15 100 % of total 5.9 9.2 1.7 16.8 najabas count 10 8 2 20 % within pa 50 40 20 100 % of total 8.4 6.7 1.7 16.8 grand total count 53 49 17 119 % of total 44.5 41.2 14.3 100 a) b) figure 3. a). bee hives kept in the house; b). beehives being placed in a khat field in chiro district of western hararghe zone of ethiopia as indicated above most (68.5%) of the respondents keep their hives under the roofs and inside the houses due to fear of theft and for easy follow up by any of the household members. however, especially putting the beehives in the house and under the roof of the house poses a serious risk to children and domestic animals, including livestock, in the sense that the bees may swarm out of their hives to sting when they feel disturbed especially during hive inspection and honey harvesting. the farmers indicated that they relocate their children and domestic animals and livestock to neighboring houses to minimize the risk. 3.6. absconding and swarming as all other livening organisms, honeybee colonies abandon their shelter, hives, at any season of the year for different reasons such as lack of bee forage, frequent disturbance by enemies, and predators and uncomfortable hive designs. absconding incidence have occurred in all pas of the study area and 50.2% of the respondents reported absconding of their bee colonies. almost all of the absconding (99.4%) occurred from the traditional hives. however, the highest percentage of absconding from traditional hive was unlikely to be due to unsuitability of traditional hives for bee nesting but was due to a large sheer number (94.8%) of traditional hives registered in the study area. the reported causes for absconding of bee colonies as indicated by respondents were lack of forage (27.4% of the cases), incidence of pests and predators specially ants (62.8 % of the cases), lack of hive maintenance (8.6%), and bad weather condition (1.2%). as described by the respondents, the major absconding months of the year was march to may (67.9%), june to august (23%) and december to february (10.1%) (table 4). according to the respondents’ views, the main causes of the highest absconding rate between march to august was indicated temesgen east african journal of sciences volume 12 (2) 127-136 132 to be the cumulative effects of lack of forage for bee that would create favorable environmental conditions for attacks by pests and predators. the farmers also indicated that the cause of relatively lower (10.1%) absconding rate observed during december to february was mainly due to better availability of flowers in the area. from this result, it could be supposed that beekeepers should not remove all honey combs during honey harvesting if the colony is in traditional and transitional hives and should not harvest honey from the bottom box (brood box) of modern hives. additionally, they should also inspect the hives more regularly and manage the colonies through prevention of pests and predators and provision of supplementary feed especially during the months of march to august. figure 4. time of the year when absconding highly occurs in chiro district of western hararghe zone of ethiopia. swarming is the natural means of reproduction of honeybee colonies. in the process of swarming, the original single colony reproduces two and sometimes more colonies. as shown in table 4, 65.5% of the respondents indicated the formation of swarms by their bee colonies while the rest, 34.5%, did not observe swarming. the 34.5% non-appearance of swarms did not totally imply absence of swarm formation. this could be due to the fact that beekeepers cannot know whether or not a colony of bees is preparing itself for swarming since internal inspection is not possible in traditional hives. on the other hand, any swarm leaves the hive at any time of the day most of the time when the bee-keeper or his/her family members are not present at home when elders are working in farm fields and juniors are perhaps running errands. therefore, the real result of a swarm occurrence could be greater than the indicated figure. concerning major swarming period of the year, 46, 52.3 and 1.7% of the respondents indicated september to november, december to february, and june to august to be major swarming months of the year. accordingly, almost all (98.3%) of the respondents pointed out that september to february is the time of major swarm formations in the study area. these results indicate that if bee colonies are frequently inspected and followed up during september to february, a considerable number of swarms could be captured and prevented from leaving the hives, which can partly improve preservation of bee colonies table 4. degree and season of bee swarming in sample peasant associations in chiro district of western hararghe zone of ethiopia. variable peasant association total chiokala arbarakate arbahore madicho ifabas najabas n(20) n(20) n(20) n (19) n(20) n(20) n (119) % % % % % % % occurrence of swarming presnt 70 80 45 63.2 70 65 65.5 absent 30 20 55 36.8 30 35 34.5 swarm occurrence months sep to nov 65 95 20 15.8 40 40 46.0 dec to feb 35 5 80 84.2 50 60 52.3 march to may 0 0 2 0 0 0 0.0 jun to aug 0 0 0 0 10 0 1.7 3.7. hive inspection and management inspection of hives is one of the mechanisms through which problems faced in honey production are observed and identified. this would help to take necessary corrective or precautionary measures and/or to decide on early harvesting before the problems worsen. there are two types of hive inspection. these are external (without opening up of the hive) and internal (with opening up of the hive). all of the respondents pointed out that they make external inspections of their hives sometimes, but none of them inspected their hives internally. concerning the frequency of external inspection, 3.2 % of the respondents (beekeepers) visited their hives every day while 30.2% of them visited their hives once every week and the remaining ones (65.6%) visited their hives at least once during honey harvesting seasons to check if the hives have been colonized by bees. internal hive inspection was totally unknown to the respondents and hence, none of them inspected to cheek the condition of the queen, production of additional queens to create new bee swarms, production level of brood, and temesgen practices and challenges of beekeeping 133 presence or absence of pests and disease. the respondents indicated that the major reason for absence of internal hive inspection was the impossibility of hive inspection under traditional beekeeping condition, and lack of knowledge on what activities or conditions of the bees in the hive need inspection. this result agrees with the findings of other researchers (kerealem, 2005; tesfaye and tesfaye, 2007) who reported that farmers in ethiopia do not commonly practice internal hive inspection due to the difficulty experienced in inspecting traditional hives internally i.e., fixed combs are attached to the walls of traditional beehives. the only management activities done by some of the respondents were cleaning their apiary for prevention of ants. about 52.7% of the respondents cleaned heir apiaries (areas around the hives) and put ash under the hive stands to avoid encroachment by small ants while the remaining 47.3% did not at all clean their apiaries. figure 5. traditional hives invaded by weeds and exposed to attacks by pests and diseases in chiro district of western hararghe zone of ethiopia. during the survey, it was observed that most of the respondents (74.3%) did not properly manage their modern beehives. this might be due to lack of training and knowledge on improved beekeeping practices, lack of supervision or follow up by extension agents after distribution of the hives by donors. this could also be attributed to slovenliness of the beekeepers. about 74.3% of the modern hives did not have hive stands; they were merely placed directly on the ground (fig 6 a. this condition would subject the hives to invasion and damage by weeds that cover the entrance of the hives (figs. 5 and 6a). only 25.7% of the respondents place placed their hives on hive stands and managed them relatively well. the overgrow weeds would dislodge pollen and nectars that the bees collected while they try to re-enter the hives. a) b) figure 6 a. modern hives placed directly on the ground in chiro district of western hararghe zone of ethiopia; b. modern hives places on hive stands in grasses. 3.8. harvesting honey and other beehive products according to all respondents, honey is harvested at the time when beekeepers expect it to be ripe without any prior inspection. 67.4 % of the respondents indicated that they estimate the honey harvesting time simply by waiting for the end of flowering season while 33.6% use crowding of the entrance of hives by bees and smelling honey aroma as indicators of honey ripening. during honey harvesting from traditional hives, beekeepers cut and pull the fixed combs one by one. pollen, brood, and honey combs were removed and all kept in the same container. any comb pulled out of the hive (if it is empty) could not be returned. 67.4% of interviewed respondents used wood for smoking during harvesting while the remaining respondents (32.6 %) used cow dung. almost all (98.3%) of the respondents used direct smoking using cow dung and/or selected wood during honey harvesting while only 1.7% of the respondents used modern smoker for producing smoke. the small percentage of using modern smokers is attributed to lack of awareness of farmers on existence of such a device. the farmers intimated to the researcher that sometimes using direct smoke was one of the causes for serious fire accidents. during harvesting of honey from traditional hives, most of the respondents (83.7%) left some honey combs for the colony to prevent starvation, while 16.3% of the respondents harvested the whole content leaving the hive empty. in the study area, honey is harvested two times a year provided that bees did not abscond and/ or migrate before the second honey fallow season. the majority of the respondents (73%) collect large amounts of honey once during november to december in a year followed by twice (25%) during the mentioned time and may and june. this might be attributed to the difference in availability of abundant flowering plants between the two seasons. this result also agrees with the finding of nuru (2007) who indicated these months as the two main honey flow and harvesting periods of the year. in the first honey harvesting period, the main reason for availability of honey in larger quantities might be attributed to the presence of flowering crops and flowering plants while temesgen east african journal of sciences volume 12 (2) 127-136 134 in the latter period, potential flowering ability of different plants could be the major reason. the average honey yield in the survey area was 7.64 kg/colony from traditional hives (ranging from 5 kg to 12 kg/colony) while the annual average honey production was 39.1 kg/year /available colonies/household (ranging from 6 kg to 67 kg/year). as indicated by all of the respondents, bees wax is not harvested for utilization. the crude wax is harvested with honey and then broken down and sold together with the crude honey. after cutting the combs from the hive, if it has no any honey or is dry, the farmers destroy it either by burning or burying in the soil. according to the respondents, the main reasons for not collecting beeswax were lack of knowledge on the importance as well as its complex processing system. only 2 of the 119 respondents knew that wax could be processed and sold at local and international markets. wax is one of the most expensive and highly demanded bee products whose price is about three times more than the price of pure honey. all of the respondents had not any awareness and even did not hear other bee products; bee pollen, propolis, royal jelly and bee venom, could be produced and marketed. the result could suggest that improved practice-oriented training and awareness creation should be delivered to the farmers of the study area to produce at least some of the hive products and generate additional income from beekeeping. 3.9. honey bee pests and predators based on the result of this study, the existence of pests was a major challenge faced by farmers in beekeeping activities. the farmers indicated that ants, wax moth (galleria mellonella), lizard, spider and honey badger and birds were the most harmful pests in decreasing order of importance (table 5). similar findings were reported by solomon (2009) in the central and southeastern highlands of ethiopia respectively. additionally (brad, 2002) revealed ants, honey badgers, bee eater birds and wax moth devastate honey bee colonies and products especially during periods of dearth in gondar province in ethiopia. this survey revealed that 59.1% and 21.4% of respondents observed ants and wax moth as serious problems that frequently weaken the strength of the colony and resulted in absconding. some of the respondents (46.8%) indicated placing ash under the hive stands and cleaning the apiary as a good preventive system against ants while the remaining 53.2% could not totally control the ants. the result implies that research should be conducted to find better ways of controlling ants and wax moths in honey production. table 5. pest and predators of honey bees in chiro district of western hararghe zone of ethiopia; b. modern hives places on hive stands among grasses. major pest and predator total sample (n=120) percent rank ants 59.1 1 wax moth 21.4 2 lizard 11.8 3 spiders 7.7 4 honey badger 5.4 5 birds 3.2 6 total 100 3.10. challenges faced in beekeeping in the study area each bee-keeper involved in the study was requested to prioritize the challenges mentioned. accordingly, inadequate knowledge and practical skills (technical shortcomings), lack of bee colonies, poor extension service and pest and predators were found to be the top four challenges for beekeeping in the area. the detailed results are summarized in table 6. thus, shortage of bee colonies was the second most important challenge in the study area. some of the respondents who were members of beekeeping cooperatives indicated that they have 20 modern hives from ngo called cisp but due to lack of bee colonies, they kept the hives empty for two years without any function. this implies the necessity of queen rearing and colony multiplication technology intervention to alleviate the problem in the study area. according to the respondents, although the extension service workers told them the importance of using improved hives and technologies, no one practically demonstrated to them how to use them or the whole operational systems, which is from colonizing the hives with bees to harvesting the products. these problems may lead to low yield and quality honey produced in the area and inefficient utilization of both modern and traditional beehives that exist in the study area. according to discussions made with some of the development agents (das) working in the study area, some of the major reasons for lack of technical support were lack of skill on modern hive operations as a result of absence of practical oriented training programs, absence of incentives that would consider the nature of beekeeping management, in which case hive operation is done after regular working time (after 6:00 pm ). temesgen practices and challenges of beekeeping 135 table. 6 major challenges identified by respondents in the district in chiro district of western hararghe zone of ethiopia; b. modern hives placed on hive stands among grasses. no constraint degree of problem (%) 1 lack of knowledge 29.6 2 lack of bee colonies 26.1 9 poor extension service 12.5 3 pest and predator 9.3 4 lack of beekeeping equipment 7.6 5 lack of bee forage associated with deforestation 6.4 6 absconding 4.3 7 application of chemicals 2.1 8 poor storage facilities 1.2 10 drought 0.6 11 market problem 0.2 12 disease 0.1 total 100 4. conclusions the results of this study have demonstrated that honey production is widely practiced by farmers in the study area in which both men and women participate. however, the results have indicated that there are a number of problems that lower both the yield and quality of honey and its products obtained by farmers. this is attributed mainly to shortage of bee colonies, inadequate technical know-how and practical skills to properly manage hives and bee colonies, high price of modern hives and their accessories, lack of practically supported extension services on modern beekeeping technologies, incidences of pests like ants and wax moths, low participation of women due to dominance by men, and seasonal availability of bee forage and flowers. the results imply that extension supports are required to be given to honey producing farmers by providing different technologies and enhancing their knowledge and skills through training to improve management of beehives and enhance the yield and quality of honey and its products. there is also a need to educate farmers on producing diverse honey bee products especially wax as well as producing new bee colonies through queen rearing. future research needs to look into eliciting concrete information on better and adaptable ways of managing honey bees under farmers’ conditions, including hive and colony management as well as production of wax and rearing of bee queens. 5. acknowledgements i thank haramaya university, office of research and extension for financing and facilitating this research. my thanks are also due to chiro woreda livestock agency workers for providing secondary data on beekeeping and for facilitating primary data collection. i am also thankful to the development agents and beekeepers working in the study area for their willingness to be interviewed and for giving me all necessary information. 6. references adebabay kebede, kerealem ejigu, tessema aynalem and abebe jenberie. 2008. assessment of the status of beekeeping in amhara region. amhara regional research institute, bahir dar, ethiopia. pp. 32-35. ayalew k. 1990. the honeybees (apis mellifera) of ethiopia. a morphometric study. m.sc. thesis, agricultural university of norway, norway. ayalew kassaye and gezahegn tadesse. 1991. suitability classifi cation in apicultural development. moa (ministry of agriculture), addis ababa, ethiopia. brad, b. 2002. taking the sting out of beekeeping beekeeping rid lands of information network east africa (cd-rom), pp: 1-4 fao. 2009. bees and their role in forest livelihoods. a guide to the services provided by bees and the sustainable harvesting, processing and marketing of their products. rome, italy. gidey, y. and mekonen, t. 2010. participatory technology and constraints assessment to improve the livelihood of beekeepers in tigray region, northern ethiopia. momona ethiopia journal of science, 2 no.1. hbrc (holetta bee research centre). 2003. annual progress report 2002/2003. hbrc, holetta, ethiopia. kerealem, e. 2005. honey bee production system, opportunities and challenges in enebse sar midir district (amhara region) and amaro special district (southern nations, nationalities and peoples region), ethiopia. m.sc. thesis presented to alemaya university. moa (ministry of agriculture), 1998. moa (minster of agriculture) /national livestock development program 1998, ethiopia, working paper 4 national resources and the environment ethiopia. livestock research for rural development 19 (11) 2007. moard (ministry of agriculture and rural development). 2012. the third residue monitoring plan for honey from ethiopia. produced by members of the ethiopian honey and beeswax producers and exporters association (ehbpea). addis ababa ethiopia nuru adgaba. 2007. atlas of pollen grains of major honey flora of ethiopia, holata bee research center, holata, ethiopia. nuru adgaba. 1999. quality state of grading ethiopian honey. in: proceedings of the fi rst national temesgen east african journal of sciences volume 12 (2) 127-136 136 conference of the ethiopian beekeepers association, addis ababa, ethiopia. solomon, b. 2009. indigenous knowledge and its relevance for sustainable beekeeping development: a case study in the highlands of southeast ethiopia. tesfaye, k. and tesfaye, l. 2007. study of honey production system in adami tulu jido kombolcha district in mid rift valley of ethiopia. east african journal of sciences (2019) volume 13 (1) 75-80 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: kedir.t.roba@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) utilization of iodized salt and associated factor in zuway dugda district, arsi zone, oromia regional state, south east ethiopia doctor edao hiso1 and kedir teji roba2* 1 zuway dugda distirict health office, arsi zone, south east ethiopia 2school of public health, college of health and medical sciences, haramaya university, harar, ethiopia abstract: iodine deficiency is a major cause of preventable mental retardation, deafness, autism, short stature, and various other defects in humans around the globe. these problems can be prevented with simple slat iodization. ethiopia has implemented slat iodization as a strategy to prevent iodine deficiency disorders (idd). however, little is known about households’ use of iodized salt and associated factors. a community based cross-sectional study was conducted from august 1, 2017 to august 30, 2017 in rural zuway dugda, arsi zone, oromia regional state, south east ethiopia. a total of 402 households were selected using a systematic random sampling technique. data were collected using structured questionnaires and household salt use was tested using the rapid test kit from the salts used during the previous night. bivariate and multivariate analyses were performed to determine household uses of salt iodization. p-value of 0.05 was employed to declare statistical significance in multivariate analysis. this study indicated that 30.7% of the households had adequate iodine level (> 15ppm) in their salts while 60.1%, and 8.2% of the households had inadequate iodine level (< 15ppm and no iodine at all (0 ppm) respectively. using packed type of salt (aor=2.89, 95%ci (1.54, 5.44)), having information about iodized salt (aor= 4.11 95%ci 2.42, 7.01) and storing salt in dry place (aor=3.41 95% ci (1.01, 11.51) were positively associated with utilizations of adequately iodized salts. this study revealed that the availability of adequate iodized salt in the household salt was very low. health information dissemination to every household about the storage and the importance of utilizing iodized salt is critically important and needs to be done across the study area. keywords: iodized salt; rural; arsi zone; ethiopia 1. introduction iodine deficiency is a major public health problem facing mankind. iodine deficiency causes goiter and brain damage in all ages beginning with the fetus during pregnancy (basil and emeritus, 2004), physical sluggishness, growth retardation, reproductive failure, increased childhood mortality, and economic stagnation. healthy humans require iodine, an essential component of the thyroid hormones, thyroxin and tri iodothyronine. failure to have adequate iodine leads to insufficient production of these hormones, which affect many parts of the body, particularly muscle, heart, liver, kidney, and the developing brain. inadequate hormone production adversely affects these tissues and causes iodine deficiency disorders (idd). (de benoist, andersson et al. 2004). correction of the deficiency dramatically improves school performance, agricultural output and per capita income as it typically results in educable and economically productive population (yifru et al. 2007). there is no country in the developing world where iodine deficiency is not a public health problem. about 38 million newborns in developing countries every year remain unprotected from the lifelong consequences of brain damage associated with iodine deficiency disorders (unicef 2008). the primary cause of iodine deficiency is a low dietary supply of iodine, typically in environments where the soil lacks iodine due to past glaciation, often compounded by the leaching effects of precipitation or flooding. these remove iodine from the soil, and plants and livestock become iodine deficit (zimmermann et al., 2007). the estimated productivity loss due to idd in ethiopia was birr 64 billion between 2006 and 2015 (fmoh, 2009). people living in areas affected by severe iodine deficiency may have an intelligence quotient (iq) of up to 13.5 points below that of those from comparable communities in areas where there is no iodine deficiency (who,2007; zimmermann 2007). health planners and international agencies are increasingly recognizing that the elimination of iodine deficiency is an attainable goal with important benefits for many people (mannar and john, 1995). one of the possible ways to eliminate deficiency of iodine is fortification of the nutrient in salt. salt iodization programs, like any other health interventions, require an effective system for monitoring and evaluation. salt iodization is currently the most widely used strategy to control and eliminate idd. however, to be fully effective in correcting iodine deficiency, salt must not only reach the entire affected population – in particular those groups that are the most susceptible(pregnant women and young children) – but it also needs to be adequately iodized ( who 2007). treatment of idd prevents further complication of the disease and its impact on socioeconomic effects. the world health organization (who) and the micronutrient initiative state that in order to achieve sustainable elimination of iodine deficiency at least 90% of households must be using salt and that the salt must have an iodine content of 15 parts per million (ppm) or doctor and kedir east african journal of sciences volume 13 (1) 75-80 76 more (worldvision 2011). the ethiopian standards board requires that the iodine content in salt should not be less than 50 ppm at the production point; and it is expected to be at 25 ppm at the retail level (teklit, 2015). a review of the prevalence of iodine deficiency among vulnerable population in ethiopia indicates that severe iodine deficiency in women leads to 50,000 still births annually and the country’s goiter rate had ranged from14% to 59% in 2009 to 2011 respectively (tesema et al. 2009). moreover, to the knowledge of the principal investigator, there is no a documented community based study done on household’s salt iodine level and associated factors in the households of zuway dugda district as these community are living in lowland area. many studies have been conducted to assess household’s salt iodine level and associated factors, however, studies on the household’s salt iodine level and associated factors have not be conducted in this area. therefore, this study was undertaken to assess household’s salt iodine level and associated factors in rural zuway dugda district, arsi zone, and oromia regional state. 2. methods 2.1. study area and period this study was done in zuway dugda district, which is located in arsi administrative zone of oromia regional state, south east ethiopia, about 212 km distance to the south from addis ababa, the capital city of ethiopia. based on the 2007(1999e.c) census, the district has a total population of 137, 227 of whom 67,927 are males and 69,300 are females. this area with lowland area and the population growth rate was 2.1%. there are 30 kebeles in the district ( 2 urban and 28 rural ).governmental health facilities are six health centers (2 in town and 4 in rural areas) and 32 health posts (2 in town and 30 in rural areas); this makes the district a hundred percent health coverage (woreda expert and primary health care unit directore 2016). this study was conducted from august 1st to 30 august, 2017 in rural zuway dugda district. 2.2. design and population a community based cross-sectional study design was used to select 402 households living in different kebeles of zuway dugda district who lived the area for more than 6 months were included. the targeted study populations were household’s access to iodized salt and the study participants were household members mostly (women) participated in food cooking were interviewed. households that with seriously sick head of household (particularly women) that made communication difficult to get the necessary data was excluded from the study. 2.3. sample size determination and sampling procedures the sample size was determined by using the formula to estimate a single population proportion. the sample size was calculated using population proportion (pp), that is, 48.3% taken from previous study (tsegaye, h, et al. 2016), 95% confidence level, and 5% margin of error. adding 5% for the non-response rate the final samples size was 402. data were collected from rural kebles. among 28 rural kebles five kebeles: namely hula arba, beshira, hallo, kiyansho and ogolcho were selected using simple random sampling. the sampled population were selected from the selected kebele using systematic random sampling from registry of health extension workers (hew) and proportionally allocated to size of women found in each kebele. based on this sampling 84, 83, 62 93, and 80 data were collected from hula arba, beshira, hallo, kiyansho and ogolcho kebeles, respectively. 2.4. data collection data were collected using interviewer administered structured questionnaire. the questionnaire was developed through literature review and comprised of questions based on socio demographic characteristics, knowledge, associated factors, availability and accessibility of iodized salt. data were collected by six diploma clinical nurses and supervised by one bsc nurse and one public health officer. each team was given a standard scope of work, encompassing data collection (collecting salt sample, interview of the respondent and recorded in a structured questionnaire). 2.5. determination of iodated salt to determine the availability of adequately iodized salt, the interviewer asked every sample household to provide a teaspoon of salt used for food preparation during previous night. then the salt was filled on small cup and spread flat. then two drop of test solution were added on surface of salt from white ampule and color were compare with color chart within one minute to determine the iodine concentration (intense color). if no color change appeared on the salt (after one minute) add test solution on a fresh sample up to 5 drop of recheck solution in red ampule and then 2 drops of test solution on same spot and compared the color with color chart. finally, it was categorized as 0 ppm (no iodine content in the salt), <15 ppm (light blue and have inadequate iodine), ≥ 15 ppm (deep blue, have adequate iodine content) (who. 2011). this was determined by using improved iodized salt field test kit batch no. 016 mf jun. 2016 exp nov.2017 for salt fortified with potassium iodate only. unopened ampule was used and, the kit was accurate for visual detection of potassium iodate concentration at threshold of 15 ppm and result was valid. the test kit was obtained from unicef through oromia regional health bureau. during analysis households with iodine less than 15ppm and has no ioden at all were categorized as in adequate and household with iodine concentration greater than 15 ppm were categorized as adequate based on previous study (roba et al. 2016). doctor and kedir utilization of iodized salt and associated factor 77 2.6. quality control the questionnaire was translated into afan oromo for data collection and then retranslated back into english by language experts to check for consistency. a two-day training was provided to the data collectors and supervisors on the data collection tool and the data collection procedure. the questionnaire was pretested on 5% of the sample size out of the study area to ensure its appropriate and modifications were made on questionnaire before final data collection. the principal investigator and the supervisors checked completeness of each questionnaire on a daily basis. 2.7. data processing and analysis the collected data were entered into epi info version 7 statistical software and exported to spss statistical software version 21 for cleaning and analysis. before the analysis, data were checked for completeness and then cleaned. descriptive data will be described using frequencies, percentages and will be presented using tables and graphs. logistic regression model was used to identify factors associated with adequacy of iodine in household’s salts. p-value less than 0.05 were considered statistically significant. the degree of association between dependent and independent variables were reported using adjusted odds ratio (aor) and 95% ci. 2.8. ethical consideration ethical clearance was obtained from the ethical committee of rift valley university ethical review committee. letters of support was obtained from oromia regional health bureau, arsi zone health department and zuway dugda district health office. informed verbal consent was obtained from heads of household and study participants. the participants were allowed to consider their participation and given the opportunity to withdraw from the study at any point in the course of the study. participants’ name or personal identifier was not included in the written questionnaires to ensure participants’ confidentiality. health education on the importance and source of iodized salt and proper handling of it at household level was given to participants who has no iodine in their salt by the data collectors after data collection. 3. results 3.1. socio demographic ccharacteristics of the respondents a total of 402 households participated in the study with response rate of 100%. among those, 384 (95.5%) were female, 334(83.1%) of whom were married, 322 (80.1%) were muslim, 348 (86.6%) were from the oromo ethnic group. from this group, le 256(63.7%) had formal education, 329 (81.1%) were housewives, 213 (53%) had family size more than five and 187 (45.8%) of the respondents’ average monthly income was <500 ethiopia birr (table 1). 3.2. household salt iodization and practice of handling salt during data collection, we found all (402) of the households had salt in their homes. 337(83.8) of the households were using unpacked type of salt, 64.2% of the households got salt from the retail shop, 92.8% of the respondents stored the salt in a dry place and 82.3% stored the salt for less than two months after purchase. only 25.6% of the households added salt to cooked food at the end of cooking (table 2). around 54.6% of participants heard about iodized salt, for which only 34.4% respondents got information from health workers; only 26.5% of them mentioned iodized salt is important to prevent goiter. about 72.8% of the respondents responded that they knew the effects of iodine deficiency is goiter, 77.2% of the respondents thought that iodine deficiency did not cause still birth; 83.9% mentioned that iodine deficiency did not cause mental retardation, and 79.5% mentioned that every salt contains iodine (table 3). 3.3. iodine content of household salt of the total respondents, (30.7% of the salt tested had adequate iodine (≥15 ppm) while 8.2% had no iodine in it at all (0 ppm) (figure 3). figure 3: iodine content test result at household level in communities of zuway dugda districs doctor and kedir east african journal of sciences volume 13 (1) 75-80 78 table 1. socio demographic characteristics of respondents in zuway dugda district south east ethiopia, 2017. variable category frequency percent (%) sex female 384 95.5 male 18 4.5 age group 18-31 81 20.1 32-44 176 43.8 >45 145 36.1 marital status single 17 4.2 married 334 83.1 divorced 12 3.0 widowed 26 6.5 separated 13 3.2 ethnicity oromo 348 86.6 zey 45 11.2 others* 9 2.2 religion muslim 323 80.3 orthodox 64 16.0 protestant 7 1.7 catholic 8 2.0 educational status no formal education 146 36.3 formal education 256 63.7 occupational status house wife 329 81.8 government employer 34 8.5 private employer 39 9.7 family size(justify <=5 189 47 >5 213 53 monthly household income(justify <500 ebr 185 46.0 501-1000 141 35.0 >1000 76 19.0 note: *ahahra, gurage table 2. household salt utilizations in zuway dugda district, south eastern ethiopia, 2017. variable category frequency percent (%) type salt used packaged 65 16.2 not packaged 337 83.8 place to buy salt open market 258 64.2 retail shop 144 35.8 salt exposure to salt sunlight yes 7 1.7 no 395 98.3 washing the salt before use yes 1 0.2 no 401 99.8 salt storage place dry area 373 92.8 not dry place 29 7.2 salt container with cover 354 88.1 without cover 48 11.9 duration of salt storage at household level <=2 months 331 82.3 >2months 71 17.7 time salt is added during food cooking at early beginning of cooking 121 30.1 at middle of cooking 178 44.3 at the end of cooking 103 25.6 3.4. factors associated with utilizations of iodized salt in the households the present study indicated that having formal education, using packed type of salt, buying salt from retail shop, having information about iodized salt and storing salt in dry place were significantly associated presence of adequate iodine in salt during bivariate analysis. table 3. knowledge of respondents regarding the importance of iodized salt in communities of zuway dugda district, 2017. variable category frequency percent (%) have you heard about iodized salt no 219 54.6 yes 182 45.4 information source about iodized salt from health worker 14 7.6 from radio 145 79.7 from their child 15 8.2 from neighbors 8 4.4 know importance of iodized salt , n=402 to keep healthy 123 30.6 to prevent from goiter 90 22.4 better than other 77 19.2 to grow well 29 7.2 i don’t know 83 20.6 know cause of goiter, n= 217 yes 158 39.3 no 244 60.7 iodine deficiency cause still birth, n= 158 yes 48 30.4 no 110 69.6 iodine deficiency cause mental retardation , n=158 yes 35 22.1 no 123 77.9 doctor and kedir utilization of iodized salt and associated factor 79 using packed type of salt, buying salt from retail shop, storing salt in dry place and having information about iodized salt were significantly associated with household salt iodization. participants who had packed type of salt were 2.89 times more likely to have adequate iodine in their salt than those who had not (aor=2.89,95%ci (1.54,5.44)). those participants who purchased salt from retail shop were 1.97 times more likely to have adequate iodine in their salt than those who had bought it from the open market (aor= 1.97 95%ci (1.19,3.28). households who had information about iodized salt were 4.11 times more likely to use adequately iodized salt than those whose had no information (aor= 4.11 95% ci( 2.42,7.01) and storing salt in dry place was 3.41 times more likely to lead to adequate iodine in their salt than those store it t in a damp place (aor=3.41 95% i (1.01,11.51) (table 4). table 4. final model of predictors of adequately iodized salt availability in multivariable logistic regre ssion in zuway dugda district, south east ethiopia, 2017. variable iodine level in freq (%) cor aor >15ppm <15ppm educational status no formal education 32(21.3) 114(78.1) 1 1 formal education 91(35.7) 165(64.3) 1.97(1.24,3.16)* 1.29(0.76,2.18) type of salt used packed 40(61.5) 25(38.5) 4.88(2.79,8.52)* 2.89(1.54,5.44)* not packed 83(24.7) 251(75.3) 1 place to buy salt open market 56(21.70) 202(78.3) 1 1 retail shop 67(46.9) 77(53.1) 3.18(2.04,4.95)* 1.97(1.19,3.28)* place to store dry place 119(32) 253(68) 2.94(1.0,8.64)* 3.41(1.01,11.51)* not dry place 4(13.8) 26(86.2) 1 1 do heard about iodized salt no 24(13.2) 158(86.8) 1 1 yes 99(45.4) 120(54.6) 5.48(3.3,9.10)* 4.11(2.42,7.01)* note: *significantly associated in multivariate logistic regression at p≤0.05 4. discussion this study indicated that 30.7% of the households salt contained adequate iodine (>15ppm). using packed type of salt, having information about iodized salt and storing salt in dry place were found to be positively and statistically significantly associated with utilization of adequate salts. this study revealed that a small proportion of the households (30.7%) was using adequately iodized salt. this is very low compared to study conducted in india in which 51% of households had iodized salt (government of india office of salt commissionner 2010). again, the households use of iodized salt in this study was lower than the findings of studies conducted in southern ethiopia, sidama zone, bensa woreda, which found 45.2% of households used iodized salt (masresha tsegaye, dejene hailu et al. 2016) and rural communities in laelay maychew district, northern ethiopia which also found 33% of households used iodized salt (gidey b, alemu k et al. 2015). these differences might be due to differences in sociodemographic characters of the study areas as this study area is lowland and iodine concentration in salt is naturally low as a result of its volaitility. however, who recommends that more than 90% of the households should utilize adequately iodized salt to eliminate idd (who, 2007). therefore, the observed percentage was inadequate and require massive government intervention to reach universal salt iodization. in this study, knowledge of respondents about the benefit of iodized salt and its effect on preventing idds was noted to be poor. overall, only 5.9% of respondents know the important of iodine is to prevent iodine deficiency disorder and only 22.1% of respondents know iodine deficiency cause still birth. similarly, low level of communities’ knowledge was reported at another area in the country (masresha et al. 2016). unless households get access to information about how to store iodized salt, know the importance of it and the consequences of not using unionized salt to reduce idd. therefore, building the communities knowledge about the importance of salt iodization to containing idd is an important intervention. using packed salt at the household level was significantly associated with availability of adequate iodine in the salt. a study in sidama zone, bensa woreda showed households that were using packed type of salt containing adequate iodine compared to their counterparts. households who store their salts dry preferably in a cool place and away from strong light had adequate iodine (masresha t,, dejene het al. 2016). another similar study in laelay maychew district in northern ethiopia showed that packed salt was mostly adequately iodized compared to nonpackaged salt (gidey b et al. 2015). it’s clear that exposing iodized salt to households or using unpacked salt gradually reduces iodine concentration in salt due to its volatile nature. however, iodine content will remain relatively constant if the salt is packed dry with an impermeable lining such as polyethylene bags. doctor and kedir east african journal of sciences volume 13 (1) 75-80 80 5. strength and limitations of the study first, the study provided insights into salt iodation adequacy and usage based on the households and determine that iodized salt use level is inadequate and fall below the who’s recommendation. this can help nutritionists and public health experts to implement health promotion campaigns and awareness of using iodizes salt. second, salt was tested immediately on field and families were informed about the status of their salt. this has the potential to increase the use of iodized salt among the households in the study area. this study used rapid field-testing kits to determine availability of adequately iodized salt from salt samples which did not include titration level of iodine and urinary iodine. another limitation of this study is that most of the answers to the questionnaires that were collected through interview may lead to social desirability bias. to reduce this bias, data were collected in multiple pass to minimize this bias. 6. conclusion and recommendations the availability of adequately iodized salt at the household level was very low compared to the who’s recommendation. awareness should be given to households on proper storage, handling, place to buy salt, and type of salt used and to be bought . 7. acknowledgments the authors thank zuway dugda administration health office and six health centers management team for their support and encouragement and for their help in providing us transportation, materials and facilitating every activity during data collection. we deeply thank the data collectors, health extension workers and study participants who sacrificed their precious time to make this research possible. we would like to thank arsi zone health department for provision of test kit and zeway dugida woreda for provision of funds for data collectors. 8. reference de benoist, b., andersson, m., egli, i. m., el bahi, t., allen, h. and w. h. organization who 2004. iodine status worldwide: who global database on iodine deficiency. fmoh. 2009 2009. high-level salt iodisation launching and scale-up event. public relations department and unicef ethiopia: 1. gidey, b., alemu, k., atnafu, a., kifle, m., tefera, y. and sharma, h. r. 2015. availability of adequate iodized salt at household level and associated factors in rural communities in laelay maychew district, northern ethiopia. journal of nutrition and health sciences 2 (1):. 103. doi: 10.15744/23939060.1.403 government of india office of salt commissionner 2010. iodized salt coverage study 2010 conducted across eight states in india. 2010." micronutrient initiative. masresha, t., dejene, h. and menen, z. 2016. availability and utilization of adequately iodized salt by urban and rural households and associated factors in southern ethiopia, sidama zone, bensa woreda: a comparative cross-sectional study. intl j food sci nutr engin. 2016;6(3): 62–71. 10.5923/j.food.20160603.03. roba, k. t., o’connor, t., belachew, t., o’brien, n. 2016. serum zinc, iron and urinary iodine levels and their relationship to other indices of malnutrition among lactating mothers in two agroecological zones of rural ethiopia. j nutr health sci. 3(2): 202. teklit gebregiorgis ambaye. 2015. knowledge of iodine deficiency disorders and intake of iodized salt in residents of mekelle tigray, ethiopia. journal of food science and nutrition therapy: 002-007. tesema, m., belay. a, zerfu. d., abinet, t. a., kebede, s. eshetu, aregash, s., zelelew, a. and kebede, a. (2009). reviews of the prevalence of iodine deficiency among vulnerable population in ethiopia. micronutrient forum global conference addis ababa. tsegaye, m., hailu d and zegeye, m. 2016. availability and utilization of adequately iodized salt by urban and rural households and associated factors in southern ethiopia, sidama zone, bensa woreda. international journal of food science and nutrition engineering 6(3): 64-68. unicef. 2008. sustainable elimination of iodine deficiency. venkatesh, m., and john, t. d 1995. salt iodization for the elimination of iodine deficiency. international council for control of iodine deficiency disorders: 53. who. 2007. "assessment of iodine deficiency disorders and monitoring their elimination." who. 2007. assessment of iodine deficiency disorders and monitoring their elimination. 1,52. who. 2011. using rapid test kits to measure salt iodisation at the household level. global health and wash: 2. yibrie, a. s., yifru, d., tigabu, y., tefera, tekelu, t. and birhane, t. 2007. "iodine deficiency disorders for the ethiopian health center team." 9-11. yibrie, a., s. yifru, d. tigabu, y. tefera, t. tekelu and t. birhane. 2007. iodine deficiency disorders for the ethiopian health center team. university of gondar in collaboration with the ethiopia public health training initiative, the carter center, the ethiopia ministry of health, and the ethiopia ministry of education: 1-11. zimmermann, m. 2007. key barriers to global iodine deficiency disorder control. u.s. agency for international development's health infectious disease and nutrition office (hidn), under the terms of cooperative agreement no. ghs-a-00-0500012-00.: 1. east african journal of sciences (2018) volume 12 (2) 145-152 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: heirumenure782@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) effect of processing methods and blending cereal and legume grain on some mineral and sensory qualities of weaning foods menure heiru1*, geremew bultosa2, and negussie bussa3 1dire dawa university, institute of technology, department of chemical engineering, p. o. box 1362, dire dawa, ethiopia. 2botswana university of agriculture and natural resources, department of food science and technology, gaborone, botswana. 3haramaya university, department of food science and post-harvest technology, haramaya, ethiopia. abstract: the most important nutritional problems in weaning foods consumed by infants in many parts of developing nations including ethiopia are deficiencies in macronutrients and micronutrients. in view of this, the effect of processing method and blending of teff, finger millet, and sprouted groundnut on mineral contents and sensory acceptability of weaning food gruel was investigated. the treatments consisted of three blends b1 (20% teff + 40% finger millet + 40% groundnut), b2 (30% teff + 30% finger millet + 40% groundnut) and b3 (40% teff + 20% finger millet + 40% groundnut) and six processing condition (roasting, fermentation, three duration of sprouting and unprocessed blend as a control). the experiment was laid out as a completely randomized design (rcd) in a factorial arrangement (3 x 6 = 18 treatments) and replicated three times per treatment. the mineral contents of initial ingredients and blended samples were analyzed using standard methods. processing condition had significant (p < 0.05) effect on mineral and sensory properties of weaning food gruel. on sprouting (groundnut), roasting, and fermentation, zinc content increased. the highest zinc content (3.86 mg/100 g) was obtained in response to sprouting groundnut for 12 hr in blend b3 and the lowest was (1.91 mg/100 g) in the control weaning food b1. the highest iron (32.96 mg/100 g) content was recorded for roasted weaning food of b3, while the lowest (14.70 mg/100 g) was obtained in the control blend b1. the highest calcium (304.82 mg/100 g) content was in the roasted weaning food blend b1 and the lowest (110.63 mg/100 g) was in the control blend b1. sensory analysis revealed that the most acceptable product was obtained from roasted blends of weaning food (i.e., color, flavor, taste and overall acceptability scores of 5.36, 5.66, 5.84 and 5.75 on 7 point hedonic scale, respectively). overall, the result showed, roasting or fermentation or sprouting of groundnut (12 to 24 hr and drying the sprout at 50 oc for 20 hr) and blending level at b3 have improved the nutrient quality and sensory acceptability of weaning food gruel compared to control sample. in the developing country like ethiopia factory processed weaning foods are not affordable for majority of the population, such domestic processing conditions can be promoted at each household to improve weaning food gruel quality for child of weaning age. keywords: blending ratio; fermentation; finger millet; groundnut sprouting; teff, mineral contents; roasting, sensory quality 1. introduction the growth and survival of infants after the recommended period of exclusive breast feeding of six months depends on the nutritional quality of the weaning food (ogbeide and ogbeide, 2000; dewey and brown, 2003). breast milk is a sole and sufficient source of nutrition during the first six months of infant life since it contains all nutrients and immunological factors that infants require to maintain optimal health and growth. however, towards the middle of the first year, breast milk alone is insufficient to support the growing infant. therefore, nutritious complementary foods are needed to be introduced from six to twentyfour months of age (mamiro et al., 2005). weaning foods are traditionally processed from staple cereals and legumes either individually or as composite gruel (huffman and martin, 1994; mensah and tomkins, 2003), and supposed to serve as additional source of energy and nutrients for babies at weaning (ogbeide and ogbeide, 2000). traditional methods such as roasting, germination/ sprouting, and fermentation of grains are often used separately or in combination during preparation of weaning foods. roasting is one of the processing steps involved in the nut manufacturing industry to improve the flavor, color, texture and overall acceptability of the product (ayyildiz et al., 2001). the textural characteristic of the whole-kernel is affected by the roasting condition while moisture content is reduced on roasting (boge et al., 2009). color is an important quality indicator of the roasting process (cämmerer and kroh, 2009). germination/sprouting is a food processing method by which the quality of a cereals and legumes can be improved for both digestibility, nutrient bioavailability and physiological function. during germination, enzymatic activity and bioactive compounds increase within the seed. germination is induced by rehydration of the seed, which increases both respiration and metabolic activity that allow the mobilization of primary and secondary metabolites. the process of germination comprises three unit mailto:heirumenure782@gmail.com menure et al. east african journal of sciences volume 12 (2) 145-152 146 operations: steeping, germination and drying (lee et al., 2007). germination is a practical, cost-effective, and sustainable process for production of weaning foods with minimum paste viscosity, high energy, and nutrient density (mensah and tomkins, 2003). groundnut (arachis hypogaea), teff (eragrostis tef) and finger millet (eleusine coracana) are major agricultural products grown in many developing nations especially in ethiopia. teff (eragrostis tef) provides over two-thirds of the human nutrition in ethiopia (uraga and narasimha, 1997). both teff (bultosa, 2016) and finger millet (chandra et al., 2016) are high in their nutritional quality and research toward desirable weaning food gruel processing from them are important. the most important nutritional problems in weaning foods consumed by children in many parts of developing nations are protein energy malnutrition, deficiency in micronutrients, presence of anti-nutrients and lack of hygienic processing (mensah and tomkins, 2003; millward and jackson, 2004; abrams et al., 2013). so, diets that lack animal source of food (meat, poultry, fish, or eggs and milk product) cannot meet the nutritional requirements of children ages 6 to 24 months unless supplementary foods are used. if milk and other animal source foods are not taken in adequate amounts, grain legumes should be consumed daily, preferably within the same meal, to ensure adequate nutrient requirement (mensah and tomkins, 2003). thus, weaning foods made from locally available cereals and legumes are important at weaning age. with appropriate processing and blending of cereal and legume grains that can be easily conducted at household level, there is a possibility to produce quality weaning foods. therefore, in this work, the effects of processing methods (roasting, fermentation and three duration of groundnut sprouting) and three blending ratio (%) b1 (20:40:40), b2 (30:30:40) and b3 (40:20:40) of teff, finger millet and sprouted groundnut, respectively on ca, zn and fe contents and sensory acceptability of weaning gruel were reported. 2. materials and methods 2.1. description of study site sample preparation and analysis were conducted at the department of food science and postharvest technology, haramaya university, ethiopia. 2.2. experimental materials ingredients for the composite blends were acquired from the following sources: 1) groundnut (werer 962 variety) was from babile, haramaya university research center; 2) finger millet (padat variety) and teff (gemechis variety) were from marc (melkassa agricultural research center). the grains were all obtained from the harvests of 2009/2010 cropping year. all samples were stored at room temperature until being analyzed. 2.3. experimental procedures 2.3.1. grains and nuts cleaning finger millet, teff, and groundnut were manually cleaned of debris. split and discolored seeds were discarded. groundnuts were shelled manually using gloved hands, collected and stored in sealed plastic bags. 2.3.2. weaning blend formulations weaning blends were formulated at 60% cereal to 40% legume ratios, which yield the highest projected amino acid scores based on infant lysine requirements (fao/who/unu 1985). ingredients were weighed and blended on dry matter basis. 2.3.3. treatments and experimental design samples were divided into treatment of three blends and six processing methods. the three blends were: b1 (20% teff + 40% finger millet + 40% groundnut), b2 (30% teff + 30% finger millet + 40% groundnut) and b3 (40% teff + 20% finger millet + 40% groundnut). the six processing methods were: three duration (12, 24 and 36 hr) of groundnut sprouting, roasting, fermentation and control (unprocessed blended flour). the experiment was laid out as a completely randomized design (rcd) in a factorial arrangement (3 x 6 = 18 treatments) and replicated three times per treatment. 2.3.4. processing methods unprocessed control: all the samples were cleaned, free from abnormal odors, broken seeds, dust and other foreign materials including live or dead insects before grinding to flour. finger millet and teff were milled by cyclone mill (model 3010-081p, colorado, usa) to particle size of ≤ 250 µm sieve pore size, packed in plastic bottles with screw caps and stored at room temperature prior to blending. groundnut was shelled and ground to paste using a grinding mill (model typ a11 basic, china). natural fermentation: fermentation was performed using the microorganisms naturally associated with the grain. slurries of the three composite blend levels (1:4 w/v) were made from unprocessed control (raw ingredient blend) by mixing 200 g of the sample with 800 ml of distilled water in a sterile beaker. slurries were fermented in a temperature-controlled incubator at 30°c for 72 hr (chavan and kadam, 1989). after 72 hr fermentation period, the slurries were transferred into aluminum pans, and then oven-dried (model 10 1a, china) at 55°c for 48 hr. fermented dry blends were further milled in to fine flour using a coffee grinder. sprouting of groundnut: this was performed in a dark room following the modified method of griffith et al. (1998). groundnut were rinsed and soaked in distilled water (1:3 w/v) for 9 hr at ambient temperature (2325oc). seeds were blot dried and placed on perforated aluminum pans lined with filter paper, then placed in a dark, temperature-controlled cabinet at 30oc for 12, 24 and 36 hr for sprouting. sprouted seeds were rinsed twice daily with distilled water to reduce microbial growth and to maintain adequate hydration. after sprouting, seeds were dried in a forced air oven (model 101-1a, china) at 50°c for 20 hr. seed coat of dried menure et al. effects of processing method and blend on qualities of weaning food 147 sprout groundnut was removed manually using hand gloves and milled to paste by a grinding mill (model typ a11 basic, china). roasting: the ingredients were roasted using flat griddle until acceptable uniform roast color, aroma and flavor developed and then cooled under room temperature. medium roasted groundnuts were coarsely ground into paste using a coffee grinder mill. roasted finger millet and teff were milled by cyclone mill (model 3010-081p, colorado, usa) to fine flour (≤ 250 µm sieve pore size), packed in plastic bottles with screw caps and stored at room temperature prior to blending. then the flours of roasted finger millet and teff were mixed with groundnut paste. 2.4. mineral analysis the mineral (zinc, iron and calcium) contents of initial ingredients and blended samples of the weaning food flour were analyzed using standard methods by atomic absorption spectrophotometer (aacci, 2000 method 40-70). 2.5. sensory evaluation sensory acceptability was evaluated by 50 undergraduate, postgraduate students and staff members of the department of food science and postharvest technology, haramaya university. the weaning food gruels were prepared by mixing 135 g of flour with 900 ml of distilled water (15% w/v). the slurries were cooked in a boiling water until 15 min with regular stirring to prevent lump formation. just before each test session, orientation was given and the cooled sample (about 45 min) were served on a plate with spoon as three digit codded samples in a random order to judges. water in a cup was provided to cleanse carryover after each taste. the sensory attributes: taste, visual color, flavor and overall acceptability were evaluated on a seven point hedonic scale (7 = like extremely and 1 = dislike extremely). 2.6. statistical analysis a triplicate data were subjected to analysis of variance (anova) using the statistical analysis system (sas institute and cary, nc). means significant difference were separated by duncan’s multiple range tests at p < 0.05. 3. results and discussion 3.1. mineral contents mineral contents of teff, finger millet, and groundnut used in the weaning food gruel the zinc and iron contents were highest in teff, followed by groundnut and finger millet (table 1). the calcium content was highest in grain teff followed by finger millet and peanut. almost similar zinc content (2.86 mg/100 g), but lower iron content (36.18 mg/100 g) was reported in grain teff by abebe et al. (2007). the calcium and zinc contents determined in grain teff were almost similar to the value reported previously by urga et al. (1997). in addition to grain teff variety, the variation in mineral composition of the soil on which the teff plant was grown and differences in the postharvest handling practices of grain teff, particularly difference on soil contamination degree during threshing are contributors toward grain teff mineral contents difference. the zinc content of groundnut seed was in the range 0.0-6.5 mg/100 g reported by asibuo et al. (2008). the finger millet zinc and iron contents found in this study was almost similar to the value reported by mamiro et al. (2001) (i.e., zinc = 2.05 mg/100 g and iron = 5.48 mg/100 g), but were lower than the value reported by chandra et al. (2016) for calcium (344 mg/100 g) and zinc (2.3 mg/100 g). the analysis shows high mineral content to the weaning food blend can be contributed by teff. also high calcium and iron to then blend are contributed by finger millet and groundnut, respectively. table 1. the mineral contents of grains used for processing of weaning food. grain zn (mg/100 g) fe (mg/100 g) ca (mg/100 g) teff 3.10 ± 0.03 21.13 ± 0.38 152.91 ± 3.44 finger millet 1.58 ± 0.03 7.24 ± 0.40 139.20 ± 3.12 groundnut 2.79 ± 0.00 19.16 ± 0.37 78.51 ± 3.12 note: all values are mean ± sd on dry matter basis 3.2. effect of blending ratio and processing method interaction on mineral contents of weaning food the interaction effect of blending ratio and processing method significantly (p <0.05) influenced zn contents of the blended weaning food flour (table 2). the highest zn content (3.86 mg/100 g) was recorded for 12 hr sprouted groundnut blend (b3) and lowest (1.91 mg/100 g) was in b1 of unprocessed control weaning food flour. the increase in mineral contents of the weaning food in response to processing of the grains can be attributed to the destruction of anti-nutrient (phytic acid and condensed tannin) factors that chelates mineral elements and make them not bio-unavailable. germination enhances bioavailability of zn, fe and ca and improve protein quality in maize, legumes, groundnuts, pumpkin and millet seeds (sandstrom, 2001). also germination and malting induce hydrolysis of phytate and hence increase zn, fe, ca and magnesium absorption (sandström, 2001; gharibzahedi and jafari, 2017). the net effect on the nutrient bioavailability depends on the balance between factors that either inhibit or enhance nutrient absorption and/or utilization in the whole diet (sandström, 2001; gharibzahedi and jafari, 2017). some inherent anti-nutritional factors such as protease inhibitors, phytate, tannins and other phenolic compounds, oxalic acid and saponins are plant menure et al. east african journal of sciences volume 12 (2) 145-152 148 constituents which play an important role in biological functions of plants. these compounds, in humans, reduce the digestibility of nutrients and the absorption of minerals (dicko et al., 2005). due to the various processing methods (germination/sprouting and fermentation) phytates can be hydrolyzed by phytase enzymes and such processing leads to improved mineral absorption in cereals/legumes food products. table 2. effect of blending ratio and processing method interaction on mineral contents of weaning food. blend zn (mg/100 g) fe (mg/100 g) ca (mg/100 g) unprocessed control b1 1.91 ± 0.03o 14.70 ± 0.39k 110.63 ± 3.64k b2 2.34 ± 0.03m 16.24 ± 0.00i 112.39 ± 3.39kj b3 2.07 ± 0.03n 17.59 ± 0.00g 118.25 ± 3.46j roasted b1 2.55 ± 0.03kl 19.79 ± 0.00d 304.82 ± 5.86a b2 2.71 ± 0.03j 26.45 ± 0.02b 264.51 ± 5.80c b3 2.86 ± 0.02i 32.96 ± 0.00a 293.14 ± 5.87b fermented b1 3.19 ± 0.03h 19.51 ± 0.01e 138.77 ± 5.59i b2 3.21 ± 0.03h 26.23 ± 0.00b 151.37 ± 5.90fg b3 3.32 ± 0.02g 18.76 ± 0.00f 115.47 ± 5.77kj 12 hr sprouted groundnut blend b1 3.66 ± 0.02d 15.44 ± 0.38j 139.01 ± 5.89i b2 3.71 ± 0.03c 16.06 ± 0.39i 142.68 ± 3.46hi b3 3.86 ± 0.03a 17.61 ± 0.00g 146.47 ± 3.48gh 24 hr sprouted groundnut blend b1 3.43 ± 0.03f 16.71 ± 0.38h 150.61 ± 0.04fg b2 3.50 ± 0.01e 17.98 ± 0.38g 157.68 ± 3.40ef b3 3.77 ± 0.00b 19.11 ± 0.38ef 162.07 ± 0.04de 36 hr sprouted groundnut blend b1 2.53 ± 0.02l 15.40 ± 0.38j 156.95 ± 0.10ef b2 2.58 ± 0.03k 19.22 ± 0.39e 162.69 ± 0.09de b3 2.72 ± 0.03j 20.31 ± 0.00c 166.17 ± 3.14d mean 3.00 19.59 166.31 cv 0.93 1.32 2.53 note: mean ± sd within a column with the same letter are not significantly different (p0.05); cv=coefficient of variation; b1=20% teff + 40% finger millet + 40% groundnut; b2=30% teff + 30% finger millet + 40% groundnut; b3= 40% teff + 20% finger millet + 40% groundnut. iron content varied significantly (p < 0.05) among the blends and processing methods (table 2). the highest value of iron (32.96 mg/100 g) was recorded for roasted weaning food samples of blend (b3) where teff content in the blend was high, while the lowest value (14.70 mg/100 g) was recorded for b1 of unprocessed control flour (i.e., where teff content in the blend was low). the interaction of blending ratio and processing condition had a significant effect (p < 0.05) on calcium content of blended weaning food sample (table 2). the highest calcium content was recorded for b1 of roasted weaning food sample (304.82 mg/100 g) and the lowest (110.63 mg/100 g) was recorded for b1 of control weaning food sample. with roasting an increase in zinc, iron and calcium contents were observed and similar was reported in other works (ayoola and adeyeye, 2010) which was implicated because of the loss of volatile components on roasting. sprouted groundnut blended food significantly (p < 0.05) affected calcium content as compared to control sample. the calcium contents of sprouted groundnut blended weaning food sample at 12, 24, and 36 hr were 142.72, 156.08 and 161.93 mg/100 g, respectively (table 3). this result showed that there was a significant improvement in the mineral contents of the blended weaning foods as compared to the control weaning food sample. 3.3. effect of main factors of blending ratio and processing condition on mineral contents of weaning food processing condition and blending ratio had a significant (p < 0.05) effect on mineral contents of weaning food sample (table 3). the highest value of zn (3.86 mg/100 g) was recorded for 12 hr sprouted groundnut blended weaning food (b3) and the lowest (1.91 mg/100 g) was recorded for b1 of control weaning food sample. increasing teff proportion had increased zinc content of blend from 2.88 mg/100 g in b1 to 3.10 mg/100 g for b3 blends. this shows sprouting groundnut and blending proportion had a significant effect on mineral contents of weaning food sample. combination of cooking and fermentation were known to improve the nutrient quality and to reduce the content of anti-nutritional factors to safe levels in comparison to other methods of processing (obizoba and atii, 1991). the work showed that ca, zn, and fe contents were significantly highest (p < 0.05) in the processed samples as compared to the control weaning food menure et al. effects of processing method and blend on qualities of weaning food 149 sample. during sprouting, roasting and fermentation, zinc content was increased. germination has been an effective treatment to remove anti-nutritional factors from legumes (e. g., phytates and galactosides) and in mobilizing secondary metabolites (uebersax, 2006). such domestic processing are cheap and more effective in improving the nutritional value of grains and legumes, and, therefore, hoped that this can contribute to nutrition improvement for infants. table 3. effect of the main factors processing methods and blending ratio on mineral contents of weaning foods. factor processing method zinc (mg/100 g) iron (mg/100 g) calcium (mg/100g) c 2.11 ± 0.19f 16.17 ± 1.26e 113.76 ± 4.59f r 2.71 ± 0.13d 26.40 ± 5.70a 287.49 ± 18.66a f 3.24 ± 0.06c 21.50 ± 3.56b 135.20 ± 16.54e sd1 3.74 ± 0.09a 16.37 ± 1.00e 142.72 ± 5.65d sd2 3.57 ± 0.15b 17.94 ± 1.09d 156.08 ± 5.28c sd3 2.61 ± 0.08e 19.14 ± 1.08c 161.93 ± 4.32b cv (%) 2.94 12.16 6.72 blending ratio b1 2.88 ± 0.61c 17.34 ± 1.98b 165.55 ± 65.34a b2 3.01 ± 0.51b 20.36 ± 4.49a 166.80 ± 48.64a b3 3.10 ± 0.64a 21.06 ± 5.56a 166.93 ± 61.53a cv (%) 2.94 12.16 6.72 note: values are means ± sd. values followed by different letters with in a column indicate significant difference (p < 0.05): note: cv=coefficient of variation, c=unprocessed control, r=roasted, f=fermented, sd1, sd2, sd3 (sprouted groundnut blend at 12, 24, and 36 hr, respectively); b1=20% teff + 40% finger millet + 40% groundnut; b2=30% teff + 30% finger millet + 40% groundnut; b3=40% teff + 20% finger millet+ 40% groundnut. there was a significant (p < 0.05) effect on the iron content of weaning food samples due to blending ratio and processing method (table 3). as compared to the control blend, the iron content has significantly increased with roasting, fermentation, duration of groundnut sprouting and with an increase in the proportion of teff in the blend. the highest (26.40 mg/100 g) iron content was obtained for roasted weaning food blend and the lowest (16.70 mg/100 g fe) was recorded for the unprocessed control weaning food blends. iron content of the blends was increased from 17.34 mg/100 g for blend b1 to 21.06 mg/100 g for blend b3. also during germination, iron content of blended weaning food significantly (p < 0.05) increased as compared to the control samples. similar to this an increase in iron and phosphorus contents in response to germination of various cereals/legumes was earlier reported by sulieman et al. (2007). in addition to reduction of phytic acid and condensed tannins, fermentation can result into lower proportion of dry matter in the food leading to an increase in the mineral bioavailability (adams, 1990; mohite et al. 2013). the calcium content of blended weaning food significantly (p < 0.05) increased in roasted, fermented and on sprouting of groundnut processing conditions, but were not due to blending ratio of three blends (b1, b2 and b3) (table 3). the highest calcium content (287.49 mg/100 g) was recorded for the roasted weaning foods and the lowest (113.76 mg/100 g) was recorded for the control weaning food sample. this shows that processing significantly increases the calcium content of weaning food flours. during germination, calcium content increased with germination time, possibly due to degradation/hydrolyses of anti-nutrients factors. malting can improve safety of foods by degradation of toxic and anti-nutritional substances such as phytates, lectin and haemagglutinins thereby can improve the bioavailability of essential minerals (iron, calcium, zinc, phosphorus) (chung et al., 2009; li et al., 2014). consistent with the results, improvements in calcium bioavailability was observed after germination and fermentation of legume samples, which was attributed to simultaneous reduction of phytic acid, tannin, and dietary fibers (ghanem and hussein, 1999). mensah et al. (1991) also reported that long period of fermentation hydrolyzed phytates and increased minerals. thus this study conquer that processing methods at household levels such as soaking, fermentation, germination and roasting of cereal staples and legumes can be manipulated to enhance the content of micronutrients and/or alter the levels of absorption modifiers to improve micronutrients bioavailability (hotz and gibson, 2001; mensah and tomkins, 2003). 3.4. sensory evaluation of weaning food the scores obtained for sensory attributes: aroma, taste, color and overall acceptability demonstrated significant (p < 0.05) differences among the formulated weaning foods tasted (table 4). the interaction of processing condition and blending ratio had significant (p < 0.05) effect on weaning food flavor. the highest value of gruel flavor (5.72) was recorded for the roasted weaning food gruel of b3 (liked very much) and the lowest (4.50) was for fermented weaning food gruel blend of b3 (liked slightly). the flavor in fermented gruel blend appeared low probably because of lactic acid. whereas in roasted weaning gruel the flavor were high because of flavor release by maillard and caramelization reactions on roasting. similar to this, roasting of legumes were reported to result in a menure et al. east african journal of sciences volume 12 (2) 145-152 150 significant improvement in the flavor of the formulations (karen et al., 1984). among sprouting duration, 12 hr sprouted peanut scored high flavor. processing method and blending ratio had significant effect on taste of the weaning food gruels. the highest taste value (6.04) was in roasted weaning food blend (b3) and the lowest (4.66) was in b2 of fermented weaning food gruel. the roasting weaning food gruel was preferred very much as compared to the other processing methods. the highest weaning food (gruel) color (5.88) was observed in b2 of control (liked very much) and least (5.08) were obtained in b2 (liked slightly) of roasted weaning food gruel. the color of food gruel made from sprouted groundnut blended sample was most preferred (liked very much), while those prepared from roasted and fermented flour was least preferred for color (liked slightly). sprouting can lead to production of more reducing sugars from starch and free amino acids from proteins and this probably helped to release color compounds on maillard and caramelization reactions during sprouted groundnut drying at 50 oc for 20 hr that influenced color acceptance. germination is known to improve the consistency, mouth feel, and taste of the product (helland et al., 2002) and in other works panelists have highly rated for formulations from germinated grains for all the sensory parameters investigated (inyang and zakari, 2008). overall acceptability of weaning food gruel was significantly (p < 0.05) affected by processing condition and blending ratio. table 4. effect of blending ratio and processing condition interaction on sensory quality of weaning food. blend flavor/aroma taste color overall acceptability unprocessed control b1 5.34 ± 1.09cde 5.74 ± 0.94abc 5.52 ± 1.07bcd 5.66 ± 0.89abc b2 5.28 ± 0.92cde 5.40 ± 1.03bc 5.88 ±1 .04a 5.68 ± 0.89abc b3 5.18 ± 0.84cde 5.58 ± 0.94bc 5.24 ± 0.65cd 5.38 ± 0.77def roasted b1 5.62 ± 1.06abc 5.82 ± 0.98ab 5.30 ± 1.01cd 5.52 ± 0.83cde b2 5.66 ± 1.06ab 5.68 ± 1.09abc 5.08 ± 1.19d 5.70 ± 1.12abc b3 5.72 ± 1.05a 6.04 ± 0.69a 5.70 ± 0.95abc 6.04 ± 0.87a fermented b1 4.98 ± 0.99de 4.92 ± 1.00d 5.10 ± 1.14d 5.20 ± 0.67def b2 4.88 ± 1.17ef 4.66 ± 0.96d 5.26 ± 1.10cd 5.14 ± 0.98ef b3 4.50 ± 1.01f 4.64 ± 1.24d 5.38 ± 1.19bcd 5.04 ± 1.04f 12 hr sprouted groundnut blend b1 5.38 ± 0.98bcd 5.50 ± 1.01bc 5.50 ± 0.88bcd 5.76 ± 0.62abc b2 5.34 ± 0.79cde 5.44 ± 0.86bc 5.82 ± 0.71ab 5.89 ± 0.77ab b3 5.16 ± 0.93cde 5.52 ± 0.99bc 5.62 ± 0.92abc 5.42 ± 0.88def 24 hr sprouted groundnut blend b1 5.22 ± 0.93cde 5.46 ± 0.73bc 5.46 ± 0.95bcd 5.38 ± 0.85def b2 5.30 ± 0.83cde 5.50 ± 1.07bc 5.58 ± 0.78abc 5.68 ± 0.84abc b3 5.04 ± 1.08de 5.42 ± 0.97bc 5.36 ± 1.00cd 5.46 ± 0.83cde 36 hr sprouted groundnut blend b1 5.28 ± 0.80ecd 5.34 ± 0.84c 5.58 ± 0.73abc 5.38 ± 0.85def b2 5.34 ± 0.93cde 5.52 ± 0.97bc 5.30 ± 0.99cd 5.68 ± 0.84abc b3 5.18 ± 1.10cde 5.46 ± 1.01bc 5.52 ± 0.99bcd 5.46 ± 0.83cde mean 5.24 5.42 5.45 5.54 cv (%) 18.82 17.95 17.91 15.57 note: values followed by different letters within a column indicate significant difference (p < 0.05) using dmrt. * = mean ± sd, cv= coefficient of variation, b1=20% teff + 40% finger millet + 40% groundnut, b2=30% teff + 30% finger millet + 40% groundnut, b3=40% teff + 20% finger millet + 40% groundnut. the highest (6.04, liked very much) overall acceptability was recorded in roasted of blend b3 and the lowest (5.12, liked slightly) was recorded for the fermented weaning food gruel. the highest (6.04) overall acceptability of weaning food was observed in the roasted sample blended at b3 and the lowest (5.04) was observed in the fermented sample of blended at b3. over all the panelists have noted that flavor, taste, color and overall acceptability of the weaning food gruel prepared were highly acceptable in roasted and sprouted groundnut processed weaning gruel. the work showed domestic processing conditions such as sprouting, roasting and fermentation have high potential for processing acceptable and nutrients improved food gruels. 4. conclusions the results of this study have demonstrated that blending cereal and legume grains as well as processing them significantly enhanced the mineral contents (zinc, iron and calcium) of the weaning food samples. processing (roasting, fermentation or groundnut sprouting) improved the mineral contents and sensory quality attributes of the weaning food sample. overall, the result showed, roasting or fermentation or menure et al. effects of processing method and blend on qualities of weaning food 151 sprouting of groundnut (12 to 24 hr and drying the sprout at 50 oc for 20 hr) and 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estimation of selected fermented foods. international food research journal, 20 (3): 1373-1377. obizoba, i. c and atii, j. v. 1991. effect of soaking, sprouting, fermentation and cooking on nutrient composition and some anti-nutritional factors of sorghum (guinesia) seeds. plant foods for human nutrition, 41 (3): 203-212. ogbeide, o. n. and ogbeide, o. 2000. mineral content of some complementary foods in edo state, nigeria. west african journal of foods and nutrition, 2: 26-30. sandström, b. 2001. micronutrient interactions: effects on absorption and bioavailability. british journal of nutrition, 85 (sup. 2): s181–s185. sulieman, m. a., eityeb, m. m., abbass, m. a. ibrahim, e. e. a., babiker, e. e. and ei tinay, a. h. 2007. changes in chemical composition, phytate, phytate activity and minerals extractability of sprouted lentil cultivars. journal of biological science, 7(5): 776-780. uebersax. m. a. 2006. dry edible beans: indigenous staple and healthy cuisine, forum on public policy, usa. uraga, k. and narasimha, h. v. 1997. effect of natural fermentation on the hcl-extractability of minerals from tef (eragrostis tef). bulletein of chemical society of ethiopia, 11(1): 3-10. east african journal of sciences (2018) volume 12 (1) 11-28 _____________________________________________________________ licensed under a creative commons *corresponding author. e-mail: mulugetadebeleb@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) characterization and classification of soils of muger sub-watershed, northern oromia, ethiopia mulugeta debele1*, bobe bedadi1, sheleme beyene2 and muktar mohammed3 1school of natural resources management and environment sciences, haramaya university, p. o. box 138, dire dawa, ethiopia. 2school of plant and horticultural sciences, hawassa university, p. o. box 5, hawassa, ethiopia. 3department of forest resources management, oda-bultum university, p. o. box 226, chiro, ethiopia. abstract: soil characterization and classification is the main information source for soil management and precision agriculture. however, much of ethiopia’s documented soil information is scanty and inadequate relative to the large size of the country and the wide diversity of soils and landscapes. this study was, therefore, conducted with the objective of characterizing and classifying soils of the muger sub-watershed in north shoa zone of oromia regional state, ethiopia. three slope classes were considered and eight representative pedons (p01-p08) were opened and described at the study area. soil samples collected from identified horizons of each pedon were analyzed following standard procedures. the field as well as the laboratory data revealed that the textural classes of most of the pedons were sandy clay loam followed by sandy clay. the soils are acidic to neutral in reaction (ph 5.59-7.24). organic carbon, cation exchange capacity, and percent base saturation of the soils range from 0.41 to 4.06%, 26.42 to 60.94 cmol (+)kg-1 and 56.58 to 93.97%, respectively. the dominance of exchangeable bases was in the order of ca2+>mg2+>k+>na+. the soils are low to high in available p and total n contents whilst varying from low to high in the contents of available micronutrients measured. the contents of soil organic carbon range from very low to high whereas the cec and percent base saturation of the soils vary from medium to very high. it is concluded that the soils are classified as mollic leptosols (eutric) (p01, p02, p05, p06 and p08), pellic vertisols (grumic) (p04 and p07), and rhodic nitisols (haplic) (p03) according to the world reference base for soil resources, and are dominantly sandy clay loam in texture varied contents of organic matter, available phosphorus, total nitrogen, and cec. the wide variations in the pedons and physico-chemical properties of the soils imply designing land use system appropriate to specific needs of each soil class as well as implementing integrated soil fertility management practices to maintain soil organic matter and essential plant nutrients. keywords: chemical characteristics; horizon; morphological characteristics; physical characteristics; pedon; world reference base 1. introduction soil is the foundation natural resource on which the life supporting system and socio-economic development depends. soils provide food, fodder and fuel for meeting the basic human and animal needs (pulakeshi et al., 2014). since soil is a scarce resource with a carrying capacity that can be stretched only to a limited extent with the help of technology (buzuayehu et al., 2002), there is an increasing demand for information on it (fasina et al., 2007; nicolaescu et al., 2009). different soil types support different land use systems and require different management options for sustainable productivity. according to fagbami (1990), the diverse nature of soil is a major reason behind allocation of land to wrong uses. hence, proper understanding of its nature and properties is necessary for judicious, beneficial, and optimal use on suitable bases (jagdish et al., 2009). soil characterization and classification contribute to alleviating adverse effects of soil diversity. they are the main information source for precision agriculture, land use planning, and management (ogunkunle, 2005) and also serve as the first milestone to develop database for formulating land use models (basanta et al., 2013). soil characterization provides information for our understanding of the soils we depend on to grow crops, sustain forests and grasslands as well as support homes and society structures (ogunkunle, 2005). a soil can be characterized by its morphological, physical, chemical, and mineralogical properties (verma and jayakumar, 2012). soil classification helps to organize our knowledge, facilitate transfer of experience and technology from one place to another and helps to compare soil properties (ogunkunle, 2005). it also links research results and their beneficial extension to field application (lawal et al., 2012 and sharu et al., 2013). moreover, it helps to produce classes that have either similar properties and/or responses to external inputs (nortcliff, 2006), and soil-related agro-technology transfer (braimoh, 2002). ethiopia is one of the most populated countries in subsaharan africa. agriculture, which is the backbone of the mailto:mulugetadebeleb@gmail.com mulugeta et al. east african journal of sciences volume 12 (1) 11-28 12 country's economy accounts for 40 percent of the gross domestic product (gdp) (undp, 2014), nearly 90 percent of foreign exchange earnings (ifdc, 2012) and supports 73 percent of employment (eata, 2013). although ethiopia has a long history of collecting basic information on soil characteristics in the form of soil surveys (eylachew, 1987, 1999; mitiku, 1987; mohammed, 2003; abayneh, 2005; abayneh and birhanu, 2006; mulugeta and sheleme, 2010; abay and sheleme, 2012; teshome, 2013; nahusenay et al., 2014), the work is restricted to a few areas. thus, much of the country’s soil information remains rather scanty relative to the large size of the country and the wide diversity of soils and landscapes (nahusenay et al., 2014). furthermore, the few existing soil resource inventories that are available are characterized at small scales with high levels of generalization, mainly based on few observations scattered over large areas. the soil resource of the whole country was studied at a scale of 1:2,000,000 (wijntje-bruggeman, 1984). particularly, in muger sub-watershed, where this research was undertaken, limited information on soil characteristics is a major constraint to application of proper management practices and technology transfer. thus, providing up-to-date and site-specific soil information to the beneficiaries based on detailed soil study at watershed level is indispensable. hence, this study was conducted to characterize the soils from morphological, physical and chemical perspectives determined at field and in laboratory, and to classify the soils of the sub-watershed according to the fao/wrb classification system. 2. materials and methods 2.1. description of the study area the study area is located in wuchale district, north shoa zone of oromia regional state, ethiopia, between 9o 34' 2.13" to 9o 35' 44.7"n latitude and 38o 43' 49.02 " to 38o 45' 41.99" e longitude. the sub-watershed is part of duber watershed in the central highlands of the country. the total area of the sub-watershed is about 931 ha. the geology of the study area is characterized by thick flood basalt (trap series), with intermediate and silicic lava and pyroclastic sediments interstratified towards the top of the series (fao, 1984; bfedo, 2009). the area is largely flat and dissected by seasonal streams and few gentle and steep slopes towards the lowland parts. the highest and lowest elevations are 2672 and 2389 meters above sea level, respectively (figure1). a 20-year climate data (1992-2011) indicate that the mean annual rainfall of the area is about 946.1 mm with peak rainy months in july, august, and september. the mean maximum and minimum annual temperatures of the area are 19.2 and 8.2 ⁰c, respectively, with a mean annual temperature of 14.3 ⁰c and the warmest and coolest months being occurring in may and november, respectively (figure 2). 2.2. site selection, field description, and soil sampling after visiting the preliminary site and gathering land information from elderly farmers, a provisional map was made based on base map (1: 50,000 scale). representative pedons were selected based on observable site characteristics and described following the guidelines for soil description (fao, 2006a). the land units were identified on the basis of topographic features and land/soil characteristics using field observations and topographic maps. soil auger observations were implemented to identify variations in soil depth and textural characteristics. a total of eight pedons (p), 1.5 m width, 2 m length and 2 m+ depth (unless soil depth was limited either by stoniness or compactness), were excavated on representative sites on the basis of auger observation and delineation of soil boundary (table 1 and figure 1). mulugeta et al. soil characterization and classification of soil of muger watershed 13 figure1. map of the study area, figure 2. mean monthly rainfall, maximum and minimum temperature of the study area (19922011). the pedons on each category were described in situ and samples were collected from every identified horizon for laboratory analysis. a total of 21 disturbed (bulk) and 21 undisturbed (core) soil samples were collected depth-wise from each genetic horizon. the core soil samples were used for determination of bulk density and soil moisture retention characteristics. the descriptions of the genetic horizons were carried out following the guidelines for field soil description (fao, 2006a) and munsell color chart (munsell color company, 1994) was used for soil color notation. table 1. location and land use types of the selected pedons. pedons sp easting northing altitude (masl) slope (%) land use landform p-01 us 0472320 1059323 2579 13 cultivated (‘tef”) undulating p-02 us 0471605 1059727 2571 11 cultivated (wheat) undulating p-03 ms 0470043 1059067 2503 7 cultivated wheat undulating p-04 ms 0471746 1059352 2496 9 grazing land undulating p-05 ms 0470879 1059228 2493 10 cultivated (‘tef’) undulating p-06 ms 0471346 1059047 2482 8 cultivated (wheat) sloping p-07 ls 0472737 1059764 2430 5 grazing land undulating p-08 ls 0470613 1058105 2419 5 cultivated (bean) undulating note: sp = slope position; u s= upper slope; ms = middle slope; ls = lower slope; masl = meters above sea level mulugeta et al. east african journal of sciences volume 12 (1) 11-28 14 2.3. soil samples preparation the disturbed soil samples were air dried at room temperature, ground, and passed through a 2 mm sieve for analysis of physio-chemical properties. for the analysis of organic carbon (oc) and total nitrogen (total n), however, a 0.5 mm sieve was used. 2.4. laboratory analyses determination of particle size distribution was carried out by the bouyoucos hydrometer method (bouyoucos, 1962). bulk density was determined using the coresampling method as described by black and hartge (1986). particle density was determined by the graduated cylinder method as outlined by bashour and sayegh (2007). the moisture contents at field capacity (fc) and permanent wilting point (pwp) were measured at the soil water potentials of -1/3 bar (33 kpa) and -15 bars (1500 kpa) respectively, using the pressure plate apparatus technique (gupta, 2004). the available water content (awc) was computed from pwp and fc values. the soil ph (ph-h2o) and 1m kcl (ph-kcl) were determined in 1: 2.5 soil to water solution ratio using a ph meter as described by carter and gregorich (2008). the electrical conductivity was measured by conductivity meter in a soil-water extract (okalebo et al., 2002). organic carbon was determined following the walkley and black wet oxidation method (walkley and black, 1934). total n of the soils was determined through digestion, distillation and titration procedures of the micro-kjeldahl method as described by bremner and mulvaney (1982). available phosphorus in the soil was determined using the sodium bicarbonate extraction solution (ph 8.5) method and the amount was measured by a spectrophotometer as described by olsen et al., (1954). exchangeable bases and cation exchange capacity (cec) of the soils were determined by the 1m ammonium acetate (ph 7) method (van reeuwijk, 1993). exchangeable ca and mg in the extracts were measured by atomic absorption spectrophotometer (aas), while a flame photometer was used to determine the contents of exchangeable k and na. micronutrients (fe, mn, zn and cu) contents of the soils were extracted by diethylene triaminepenta-acetic acid (dtpa) method (houba et al., 1989) and the contents in the extract measured by aas. 2.5. soil classification the soils were classified into different reference soil groups following the world reference base for soil resource (fao, 2014). the presence or absence of specific diagnostic horizons, properties and materials were used to distinguish soil units and subunits. a soil map was prepared using arc gis 10.0 software. 2.6. statistical analysis the data from laboratory analyses were subjected to simple correlation analysis to distinguish functional relationships among and within selected soil physicochemical properties with the help of statistical-package for social sciences (spss) software. 3. results and discussion 3.1. site characteristics of the pedons the site characteristics of the pedons indicated differences in slope, permeability, and extent of water erosion. two (p1 and p2), four (p3, p4, p5 and p6) and two (p7 and p8) pedons were on landscape positions, which are having slopes of 11-13, 7-10 and 5; and are located on slope classes of upper, middle and lower slopes, respectively (table 1). the slope gradient of the study area was categorized on the basis of fao slope gradient classes (fao, 2006a). the gradient varies from strongly sloping (10-15%), to gently sloping (2-5%). the pedon in all slope classes were found to be well drained, maybe due to the sandy clay loam texture and existence of muger gorge immediately at the outlet of the subwatershed. the slope and parent materials are the major contributing factors to the differences in the site characteristics. parent materials determine certain soil properties and drainage condition, which is among other factors to determine the type of soil (david, 2005). 3.2. morphological characteristics of the soils the morphological properties of soils; horizon, depth, color, structure, consistency and horizon boundary varied along the toposequence at the study site. all the pedons had intermediate to deep profile (50 to 200cm) except p1, p5 and p8 (table 2). the thickness of the solum varied along the toposequence, whereby the shallowest (20cm) solum with lithic contact within the 50cm depth, which may limit the root penetration for deep rooted crops was observed at upper slope, while deep (>75cm) surface layers were noted on middle and lower slopes (table 2). the differences in depth of the solum might have been influenced by shape and slope length, which are important in influencing the rate at which water flows into or off the soil if the sites are unprotected. the running water may erode soils on slopes and form thinner surface layer, a-horizon (broderson, 1994). mulugeta and sheleme (2010) also reported that landscapes position influences runoff, drainage, soil temperature, soil erosion, soil depth and hence soil formation. the distinctness of horizon boundary between surface and subsurface horizons in all pedons were clear with smooth topography, except in pedons 5 and 3 (table 2). it was clear with wavy topography both in the surface and subsurface horizons of pedon 5; whereas, in pedon 3 the surface horizon had diffused while the subsurface horizon was clear with wavy boundary. the differences in nature of the horizon boundaries may indicate the mulugeta et al. soil characterization and classification of soil of muger watershed 15 existence of variations in the processes of soil formation and partly reflecting anthropogenic impacts (cools and de vos, 2010). biological activity was relatively higher in the surface horizons and decreased with depth of the pedons, which could be associated with decreasing root biomass, aeration, nutrients and management effects down the soil profiles. the roots in different horizons of the pedons also varied from very fine to coarse in size and a few to common in quantity. the pedons showed a great variability in relation to soil color patterns. surface soil color varied from very dark gray (7.5yr3/1, dry) to dark brown (7.5yr 3/2, dry) in the upper slope; very dark gray (10yr 3/1, dry) to olive gray (5y 5/2, dry) in the middle slope; brown (10yr 4/3, dry) to dark gray (2.5y 4/1, dry) in the lower slope (table 2). the subsurface color ranged from dark reddish black (5yr 3/3, dry) to light gray (2.5y 7/2, dry) in the upper slope; dark reddish brown (2.5yr 3/3, dry) to pale yellow (5y 7/4, dry) in the middle slope; to yellowish brown (10yr 5/4, dry) to light olive brown (2.5y 5/3, dry) in the lower slopes. generally, surface horizons have a darker color than their subsurface counterparts owing to the relatively higher organic matter contents in the surface horizons. in line with this result, several authors reported that the surface horizons have a darker color than the corresponding subsurface horizons as a result of relatively higher soil om contents (ashenafi et al., 2010; mulugeta and sheleme, 2010; dinku et al., 2014). concurrent with the findings of this study, dengiz et al. (2012) indicated that soil color could be related to om, waterlogging, carbonate accumulations and redoximorphic features. similarly, nuga et al. (2006) also reported that drainage condition and physiographic position may have major influence on the soil color. there were significant variations in the grade, size and shape of the soil structure among the pedons. the structure of the soils in the surface layers of the pedons varied from strong fine crumby to weak medium angular blocky, whereas in the subsurface horizons it ranged from weak medium sub-angular blocky to strong fine sub-angular blocky (table 2). the better developed structure of the subsurface layers could be due to the relatively higher clay content of the subsurface horizons than that of the surface horizons (ahn, 1993). the soil consistence in the pedons varies among the topographic positions, whereby it ranged from loose to hard (dry), loose to firm (moist) and slightly sticky/non-plastic to very sticky/very plastic at upper slope, whereas the pedons in the middle topographic position exhibited soft to hard (dry), loose to very firm (moist) and slightly sticky/ nonplastic to very sticky/ very plastic consistence. the observed differences in soil consistence could probably be explained by the differences in particle size distribution, particularly clay content, om and nature of the clay particles. the findings of this study are in agreement with the results reported by moradi (2013) who indicated that soil consistence varied with soil texture. mulugeta and sheleme (2010) also pointed out that the friable consistence observed in the surface soils of the pedons could be attributed to the higher soil om content. 3.3. physical characteristics of the soils all profiles of the pedons had high sand and low silt content across the horizons. sand accounted for over 50 percent by weight of the particle size of the soils at the surface horizons, except for pedon 1, 2, and 3, while silt ranged from 10 to 26 percent for all the pedons. although, sand content increased with depth in the pedons except for pedons 2, 3, and 5, none of the fractions showed a consistent trend with topographic positions. similar findings were reported by mahajan et al. (2007) and lawal et al. (2012), where more coarse sand fractions in the soils were recorded due to the presence of sandy type of rocks viz., sand stone, silt stone, granite, etc. the increment in the sand fraction with increased depths might be associated with the parent material. mulugeta et al. east african journal of sciences volume 12 (1) 11-28 16 table 2. selected morphological characteristics of soils of muger sub-watershed, northern oromia. pedon horizon depth (cm) matrix color structure *1 consistence *2 horizon boundary dry moist grade size shape dry moist stickiness plasticity upper slope pedon p-01 a 0-20 7.5yr3/2 10yr3/2 we me ab ha fr sst npl c-s c 20-98 2.5y7/2 10yr5/4 we me ma sha fi st spl c-s r 98+ _ _ _ _ _ _ _ _ _ _ p-02 ap 0-80 7.5yr3/1 10yr3/1 st me sb ha vfr vst vpl c-s ac 80-90 5yr3/1 5yr2.5/2 st fn sb sha fr st pl c-s ca 90-125 5yr3/2 5yr3/2 mo me sb so fi sst spl c-s c 125-200+ 5yr3/3 7.5yr3/2 we me sb lo lo st pl _ middle slope pedon p-03 ap 0-98 7.5yr3/3 7.5yr3/2 mo me gr ha vfr sst pl d-w bt 98200+ 2.5yr3/4 2.5yr3/2 we me ab so vfr st spl c-w p-04 a 0-35 5yr2.5/1 10yr3/1 mo me cr ha vfr sst spl c-s ab 35-50 2.5yr2.5/1 7.5yr2.5/1 we me sa sha lo sst pl c-s b 50-200+ 2.5y3/1 2.5y3/1 we me ab ha vfi st vpl _ p-05 a 0-25 5y5/2 5y5/3 st me gr ha fi vst vpl c-w ca 25-58 5y7/4 5y6/4 mo fn sb ha fr sst spl c-w r 58+ _ _ _ _ _ _ _ _ _ _ p-06 a 0-60 10yr3/1 7.5yr2.5/1 st me sb ha fr st spl c-s c 60-200+ 10yr6/6 10yr4/3 mo fn ma sha fr sst npl _ lower slope pedon p-07 a 0-90 2.5y4/1 7.5yr2.5/1 st fn cr ha fi vst pl c-s b 90-150 2.5y5/3 2.5y4/3 mo me ab sha fi sst spl c-s r 150+ _ _ _ _ _ _ _ _ _ _ p-08 a 0-20 10yr4/3 10yr3/2 mo me gr lo vfr sst spl c-s c 20-90+ 10yr5/4 7.5yr4/4 mo me ab lo vfr sst spl _ note: 1*: st= strong, mo= moderate, we=weak, fn= fine/thin, me=medium, we= wedge-shaped, ab= angular blocky, ma=massive, sb= sub-angular blocky, cr= crumb, gr= granular, 2*: ha=hard, sha= slightly hard, lo= loose, so= soft, vha= very hard, fi=firm, vfr=very friable, fr= friable, vfi=very firm, nst= non-sticky, sst= slightly sticky, st= sticky, vst= very sticky, npl=non-plastic, spl= slightly plastic, pl= plastic, vpl= very plastic, c=clear, d=diffused, s= smooth, w=wavy. the silt/clay ratio ranged from 0.19 -1.44 across the profiles. this ratio is one of the indices used to assess the rate of weathering and determine the relative stage of development of a given soil. according to ashaye (1969) the silt/clay ratio <1 could mean that the soil had undergone feralitic pedogenesis. accordingly, the silt to clay ratio is generally below a unit indicating that the soils of the sub-watershed are at an advanced stage of development, except for pedon 8 (abayneh, 2005; basava et al., 2005). the total porosity in the surface layers of the soils ranged from 42.9 to 59.5% (table 3) and decreased consistently with soil depth. the decrease in the total porosity with soil depth could be due to the effect of management, limited penetration of crop roots into subsurface layers as well as relatively higher om contents in the surface horizons. this finding is in agreement with that of pravin et al. (2013) who reported decrease in total porosity with soil depth as a result of increasing compaction, decreasing of rooting effect, and organic matter content with depth. the soil water content retained at field capacity (33kpa) ranged from 20.9 to 54.3% whereas at permanent wilting point (1500kpa), it was between 13.3 to 44.7% (table 3). the low water retention values for both suctions are indication for absence of waterlogging problem at the study site, which could be related with amount of clay content and om. in accordance with the report of edoga (2010), clay offers a higher resistance to movement of water because of its high proportion of micro-pores that hygroscopically or in film store water. the available water holding capacity (awhc) of the soil varied from 3.1 to 9.6% on horizon basis and could be rated as very low to low in accordance with beernaert (1990). accordingly, the limited amounts of finer fractions, particularly in subsurface soils, could decrease the water holding capacity of the soils and limit longer period of soil water retention for uptake by plants. 3.4. chemical characteristics of the soils soil ph, electrical conductivity and calcium carbonate content the ph values of the soils in the pedons ranged from moderately acidic to neutral (5.6 – 7.3), in accordance with the rating of jones (2003). the ph-h2o values varied from 5.59 to 6.42 in the surface layers and 5.78 to 7.24 in the subsurface horizons with an increasing trend with depth in all pedons except for p-5 (table 4). similarly, the ph – kcl values ranged from 4.56 to 5.46 and 4.53 to 6.31 in the surface and subsurface soils, respectively, and the values increased with depth. this increment in ph value of soil at the bottom layers might be attributed to the accumulation of exchangeable bases and caco3. the soil ph was positively and significantly correlated (r= 0.792; mulugeta et al. soil characterization and classification of soil of muger watershed 17 r=0.587, p <0.01) with both na and k contents respectively, while it was negatively and significantly (r= -0.447, p <0.05) correlated with fe (table 9). irrespective of the topographic positions, the soils of all pedons showed very low electrical conductivity values that ranged from 0.06 to 0.07ds/m, indicating that the soils are non-saline (fao, 1988). similarly, calcium carbonate (caco3) content of the soils ranged from 2.29 to 4.78% showing an increasing trend with soil depth, except for p-6. the relatively higher concentration of caco3 at the subsurface than at the surface horizons might be ascribed to effects of leaching and parent material; similar findings were reported by ozsoy and aksoy (2007), in which case the caco3 contents increased with depth. mulugeta et al. east african journal of sciences volume 12 (1) 11-28 18 table 3. selected physical characteristics of soils of muger sub-watershed, northern oromia. pedon horizon depth (cm) particle size distribution textural class s:c ratio bd (g cm-3) pd (gcm-3) tp (%) fc (%) pwp (%) awhc (%) sand silt clay upper slope pedon p-01 a 0-20 46 22 32 scl 0.69 1.08 2.46 56.10 28.03 23.87 4.15 c 20-98 52 15 33 scl 0.45 1.11 2.73 59.49 54.33 44.79 9.54 r 98+ _ _ _ _ _ _ _ _ _ _ _ p-02 a 0-80 44 13 43 clay 0.30 1.35 2.62 48.31 39.85 33.21 6.65 ac 80-90 43 20 37 cl 0.54 1.44 2.6 44.55 31.08 25.56 5.52 ca 90-125 49 20 31 scl 0.65 1.45 2.61 44.44 27.08 23.98 3.10 c 125-200+ 45 21 34 cl 0.62 1.45 2.61 44.44 34.11 24.71 9.41 middle slope pedon p-03 ap 0-98 47 19 34 scl 0.56 1.31 2.3 42.93 30.26 21.04 9.22 bt 98-200+ 38 10 52 clay 0.19 1.47 2.61 43.59 31.82 24.90 6.92 p-04 a 0-35 49 21 30 scl 0.70 1.06 2.62 59.50 45.11 36.14 8.96 ab 35-50 47 19 34 scl 0.56 1.35 2.6 48.23 36.24 32.11 4.13 b 50-200+ 50 11 39 sc 0.28 1.42 2.48 42.85 44.54 39.62 4.92 p-05 a 0-25 52 11 37 sc 0.30 1.14 2.64 56.82 49.27 41.60 7.67 ca 25-58 51 24 25 scl 0.96 1.23 2.3 46.52 44.30 35.53 8.78 r 58+ _ _ _ _ _ _ _ _ _ _ _ p-06 a 0-60 54 16 30 scl 0.53 1.37 2.66 48.50 27.17 20.43 6.73 c 60-200+ 70 16 14 sl 1.14 1.46 2.23 34.59 20.94 13.33 7.61 lower slope pedon p-07 a 0-90 53 10 37 sc 0.27 1.19 2.37 49.79 42.98 36.37 6.61 b 90-150 54 19 27 scl 0.70 1.26 2.18 42.12 41.97 33.12 8.84 r 150+ _ _ _ _ _ _ _ _ _ _ _ p-08 a 0-20 56 26 18 sl 1.44 1.31 2.61 49.98 33.54 23.90 9.63 c 20-90+ 73 15 12 sl 1.25 1.37 2.48 44.90 31.30 24.62 6.68 note: sc= sandy clay, scl=sandy clay loam, sl= sandy loam, cl= clay loam, bd= bulk density, pd= particle density, tp= total porosity, fc= field capacity, pwp= permanent wilting point, awhc= available water holding capacity. mulugeta et al. soil characterization and classification of soil of muger watershed 19 organic carbon, total nitrogen, c: n ratio, and available phosphorus the organic carbon (oc) content varied depth-wise from 0.41 to 3.45, 0.77 to 4.06 and 0.65 to 2.56% in the upper, middle and lower topographic positions, respectively (table 5). it did not show a consistent trend across topographic positions, but generally decreased with soil depth in all pedons except p-4. according to the ratings suggested by tekalign (1991), the oc contents of the soils in the study area can be categorized as having from very low to high contents of organic carbon. lower oc contents was recorded for cultivated lands compared to grazing lands, owing to intensive cultivation with low external organic inputs coupled with soil burning ‘gaye system’ which is a common practice in the area. table 4. soil ph, ec and calcium carbonate content of muger sub-watershed, northern oromia. pedon horizon depth (cm) ph (1:2.5) ec (dsm-1) caco3 (%) h2o kcl ∆ph upper slope pedon p-01 a 0-20 5.71 4.68 1.03 0.07 3.95 c 20-98 5.89 4.53 1.36 0.06 3.95 r 98+ _ _ _ _ _ p-02 a 0-80 6.42 5.46 0.96 0.06 3.85 ac 80-90 7.07 6.29 0.78 0.07 4.06 ca 90-125 7.16 6.31 0.85 0.07 4.78 c 125-200+ 7.02 6.23 0.79 0.07 4.68 middle slope pedon p-03 ap 0-98 5.73 4.64 1.09 0.06 2.29 bt 98-200+ 5.78 5.31 0.47 0.06 3.02 p-04 a 0-35 5.66 5.21 0.45 0.07 4.16 ab 35-50 5.91 5.27 0.64 0.06 4.78 b 50-200+ 6.87 5.7 1.17 0.07 4.47 p-05 a 0-25 6.18 4.97 1.21 0.06 3.12 ca 25-58 5.93 5.25 0.68 0.06 3.22 r 58+ _ _ _ _ _ a 0-60 5.93 4.63 1.3 0.06 3.74 p-06 c 60-200+ 6.46 5.34 1.12 0.06 3.54 lower slope pedon p-07 a 0-90 6.07 5.07 1 0.06 3.95 b 90-150 7.24 6.3 0.94 0.07 4.26 r 150+ _ _ _ _ _ a 0-20 5.59 4.56 1.03 0.06 4.26 p-08 c 20-90+ 5.84 4.98 0.86 0.06 4.78 note: ec= electrical conductivity this finding is in agreement with the report of wakene and heluf (2004) with respect to intensive cultivation and leading to gradual loss of soil organic matter and that of habtamu et al. (2009) with respect to land clearing for cultivation, which aggravate om oxidation and hence reduces oc content. the total n content of the soils ranged from 0.04 to 0.25% across the different topographic positions (table 5), and could be rated as low to high in accordance with the rating of havlin et al. (1999). the distribution pattern of total n with soil depth was similar to that of oc. this was also evident from the positive and highly significant (r=0.912, p<0.01) correlation between tn and oc indicating om is the main source of n (table 9). this finding is in agreement with that of meysner et al. (2006) who indicated that as much as 93 to 97% of the total n in soils is closely associated with om. available p content of the soils in the pedons ranged from 11.71 mg kg-1 in the bt horizon of p3 to 22.01 mg kg-1 in the a horizon of p1 (table 5) and ranged from medium to high as per the rating suggested by cottenie (1980). generally, the available phosphorus content of the soils decreased with profile depth in all pedons, which could be attributed to the relatively higher oc contents in the surface layers, and application of phosphorous containing fertilizer and compost by farmers on cultivated lands. mulugeta et al. east african journal of sciences volume 12 (1) 11-28 20 cation exchange capacity, exchangeable bases and percent base saturation the cation exchange capacity of the soils ranged from 26.42 to 60.94 cmol(+) kg-1 (table 6) which is high to very high according to the rating of hazelton and murphy (2007). generally, the pedons at upper and middle slope positions had relatively higher cec than those on the lower slope position; this could be associated with soil oc and relatively high clay contents. the high cec results showed that the soil of the study area has good nutrient retention and buffering capacity. however, cec did not show a consistent trend at different soil depths. table 5. soil organic carbon, tn, c: n ratio and av. p of muger sub-watershed, northern oromia. pedon horizon depth oc% tn (%) c:n ratio av. p (mg kg-1) upper slope pedon a 0-20 3.45 0.25 13.9 22.01 p-01 c 20-98 0.69 0.06 11.8 15.73 r 98+ _ _ _ _ a 0-80 1.10 0.09 12.5 18.64 p-02 ac 80-90 1.01 0.10 9.9 18.10 ca 90-125 0.69 0.07 9.5 14.49 c 125-200+ 0.41 0.04 9.3 14.25 middle slope pedon p-03 ap 0-98 3.41 0.32 10.6 16.80 bt 98-200+ 1.10 0.10 10.7 11.71 a 0-35 3.73 0.23 16.0 15.79 p-04 ab 35-50 4.06 0.29 13.9 14.25 b 50-200+ 2.35 0.13 18.0 13.90 a 0-25 2.03 0.13 15.5 18.16 p-05 ca 25-58 1.70 0.09 19.5 13.19 r 58+ _ _ _ _ p-06 a 0-60 1.99 0.15 13.7 16.03 c 60-200+ 0.77 0.09 8.6 15.02 lower slope pedon a 0-90 2.03 0.07 29.0 13.66 p-07 b 90-150 0.65 0.09 7.4 13.13 r 150+ _ _ _ _ a 0-20 2.56 0.16 16.0 20.53 p-08 ac 20-90+ 0.73 0.06 12.5 15.02 note: om = organic matter, c: n = carbon to nitrogen ratio, tn = total nitrogen, av.p = available phosphorus exchangeable ca was the dominant cation on the exchange sites followed by mg, k and na across the pedons (table 6), showing appropriate basic cation distribution in accordance with fao (2006b). the contents of exchangeable ca and mg varied from 9.52 to 27.68 and 3.97 to 12.04 cmol (+) kg-1, respectively, whereas exchangeable k and na varied from 0.14 to 4.33 and 0.66 to 2.49 cmol (+) kg-1, respectively. generally, the contents of exchangeable bases increased with increasing soil depth, perhaps due to leaching. the exchangeable k, ca and mg contents of the surface layers of the soils are above the critical values (sims, 2000). the ca: mg ratio of the soils was in the range of 1.63-3.71. accordingly, as per eckert (1987) ratings, the results indicate mg induced ca deficiency in the soils. on the other hand, the values of k: mg ratio varied from 0.06-0.37, and in accordance with the ratings by loide (2004), mg induced k deficiency is also expected in crop production on the soils. the results suggest the need for soil management to balance the cations for optimum crop production, although their absolute values are above the critical levels. the percent base saturation of the soil of the study area varied from 56.58 to 93.97% with an increasing trend with depth, which might be due to leaching of bases from the overlying layers and subsequent accumulation in the subsurface horizons. the percent base saturation in the soils of the area was also in the moderate to very high ranges (hazelton and murphy, 2007). mulugeta et al. soil characterization and classification of soil of muger watershed 21 table 6. exchangeable bases, cec and pbs of muger sub-watershed, northern oromia. note: cec = cation exchange capacity; pbs = percent base saturation extractable micronutrient the concentrations of dtpa extracted micronutrients were in the order of fe > mn > cu > zn in all the slope positions, except pedon 5 where the concentration of cu was the smallest. however, horizons with relatively higher clay content showed a relatively higher extractable cu content and cu was also highly significantly and positively correlated (r = 0.550, p < 0.01) with clay content but negatively and significantly correlated (r= -0.518, p < 0.05) with sand (table 9). as per the rating recommended by jones (2003), the soils of the study area were found to be high; medium; very low to high and low to high for fe, mn, zn and cu respectively. this finding is in line with that of abayneh (2005) who reported fe and mn were in adequate levels across ethiopian soils. soil micronutrients are influenced by several factors among which soil om content, soil reaction, and clay contents are the major ones (fisseha, 1992). in line with this, a significant and positive correlation (r = 0.510; p < 0.05) was observed between fe and organic carbon (table 9), while cu also exhibited highly significant and positive correlations (r = 0.741; r = 0.736, p < 0.01) with oc and total n, respectively (table 9). 3.5. classification of the soils according to fao – wrb system all pedons had well-structured dark surface horizons of more than 20 cm thickness having color values and chroma of less than 3 when moist. the surface layers of the pedons contained more than 0.6 percent of oc; base saturation (by 1m nh4oac, ph 7) of > 50 percent or more throughout the horizons (table 5 and 6) meeting the criteria for a mollic diagnostic horizons. pedon 3 had deep, well-drained soil with an effective depth of 200+cm; a subsurface horizon thicker than 30 cm with more than 30% clay; moderate to strong angular blocky structure with shiny pedfaces; silt/clay ratio of <0.4 meeting the criteria for nitic sub-surface horizon. the pedon had a diffused boundary between the surface and subsurface layers; without ferric, plinthic or vertic horizon and no gleyic color pattern starting within 100 cm of the surface meeting the requirements of nitisols (fao, 2014). furthermore, the subsurface layer started at 98 cm; had high fe content; dusky red (2.5 yr3/2 moist) to dark reddish pedon horizon depth (cm) exchangeable bases (cmol (+) kg-1 ) ca:mg k:mg pbs (%) ca mg k na cec upper slope pedon p-01 a c 0-20 20-98 16.44 27.68 7.68 12.04 1.25 0.66 0.79 0.66 38.90 60.94 2.14 0.16 67.25 67.33 r 98+ a 0-80 18.92 8.80 3.13 1.40 41.18 2.15 0.36 78.31 p-02 ac 80-90 19.33 7.78 4.13 1.57 40.56 80.91 ca 90-125 19.47 8.34 4.33 1.66 48.26 70.05 c 125-200+ 20.43 8.57 3.73 1.49 39.73 86.12 middle slope pedon ap 0-98 9.52 5.83 1.21 0.74 30.58 1.63 0.21 56.58 p-03 bt 98-200+ 10.25 6.58 1.93 0.87 29.12 67.40 a 0-35 22.59 9.49 0.58 1.44 53.66 2.38 0.06 63.54 p-04 ab 35-50 20.38 8.19 0.47 1.14 52.42 57.58 b 50-200+ 24.97 9.28 0.64 2.23 54.50 68.13 a 0-25 23.09 10.91 0.87 0.87 60.74 2.12 0.08 58.85 p-05 ca 25-58 22.63 10.64 0.89 0.79 56.78 61.54 r 58+ p-06 a 0-60 15.07 6.83 1.07 0.83 48.18 2.21 0.16 57.78 c 60-200+ 12.08 4.83 1.05 1.00 28.29 67.03 lower slope pedon a 0-90 21.44 7.70 1.10 1.05 41.18 2.79 0.14 75.96 p-07 b 90-150 24.33 8.26 1.26 2.49 42.85 84.81 r 150+ a 0-20 20.68 5.57 2.06 1.40 31.62 3.71 0.37 93.97 p-08 c 20-90+ 14.97 3.97 0.14 1.27 26.42 77.03 mulugeta et al. east african journal of sciences volume 12 (1) 11-28 22 brown (2.5yr3/4 dry) color; qualifying for rhodic prefix. thus, the soils represented by this pedon were classified as rhodic nitisols (haplic) in accordance with the world reference base for soil resources (fao, 2014). the pedons 4 and 7 had thick (>150 cm) subsurface horizons with greater than 30 percent clay, wedge shaped soil aggregates and slickensides produced by shrink and swell cracks starting at the surface qualifying for vertic horizon (fao, 2014). consequently, the pedons were classified as vertisol. the surface layers (0-50cm) had munsell color values of 3 and chroma 2 and less both moist, and self-mulching granular structure qualifying for pellic and grumic prefix and suffix, respectively. the soils of these pedons were classified under pellic vertisols (grumic) in accordance with world reference base for soil resources (fao, 2014). table 7. extractable micronutrient status of soils of muger sub-watershed, northern oromia. pedon horizon depth micronutrients (mg kg-1 ) fe mn zn cu upper slope pedon p-01 a c 0-20 20-98+ 41.66 44.77 6.30 14.36 1.50 0.06 6.58 3.06 r 98+ a 0-80 52.01 15.86 0.11 2.84 p-02 ac 80-90 43.38 8.53 0.04 1.91 ca 90-125 36.14 7.33 0.12 1.40 c 125-200+ 35.00 9.49 0.05 1.53 middle slope pedon ap 0-98 98.11 5.12 4.72 7.94 p-03 bt 98-200+ 36.14 17.45 0.04 3.57 a 0-35 97.17 18.16 0.94 5.14 p-04 ab 35-50 46.32 17.23 0.60 7.51 b 50-200+ 41.14 13.13 0.49 4.33 a 0-25 61.32 17.77 4.11 2.80 p-05 ca 25-58 52.53 16.16 5.32 1.95 r 58+ p-06 a 0-60 78.40 8.15 0.97 3.78 c 60-200+ 44.48 9.01 0.09 0.59 lower slope pedon a 0-90 92.37 17.68 0.81 6.32 p-07 b 90-150 51.66 8.10 0.02 1.32 r 150 p-08 a 0-20 76.84 17.39 0.07 0.81 c 20-90+ 54.24 13.31 0.08 0.30 mulugeta et al. soil characterization and classification of soil of muger watershed 23 table 9. correlation between properties of the soils in muger sub-watershed note: *. correlation is significant at p < 0.05; **. correlation is highly significant at p < 0.01 ρb awh ρs ph oc sand silt clay ec tn av.p fe mn zn cu ca mg k na cec pbs ρb 1 -.270 .140 .427 -.447* -.037 -.164 .110 -.076 -.278 -.335 -.393 -.304 -.340 -.296 -.452* -.501* .500* .270 -.502* .223 awh 1 -.016 -.132 -.120 .225 .170 -.265 -.134 -.081 .171 .311 .237 .079 -.269 .247 .087 -.152 -.029 .023 .280 ρs 1 .032 -.051 -.496* -.116 .457* -.073 -.012 .079 -.033 .207 -.397 .002 .074 .248 .455* -.090 .157 .091 ph 1 -.404 -.177 .085 .101 .549* -.317 -.116 -.447* -.401 -.315 -.312 .338 .138 .587** .792** .126 .452* oc 1 -.206 .195 .071 .292 .912** .293 .510* .178 .278 .741** -.041 .012 -.437* -.216 .166 -.445* sand 1 .138 -.875** -.211 -.251 .102 .029 .055 .071 -.518* .059 -.389 -.430 .053 -.144 .089 silt 1 -.601** .412 .201 .310 -.051 -.137 .388 -.269 .140 -.013 .148 .064 .076 .134 clay 1 -.031 .104 -.234 .001 .023 -.247 .550** -.117 .320 .275 -.074 .079 -.137 ec 1 .328 .353 -.025 -.276 .103 .074 .201 .094 .384 .517* .177 .119 tn 1 .324 .438* -.099 .203 .736** -.244 -.134 -.307 -.210 -.015 -.444* av.p 1 .063 -.024 -.007 -.041 .164 -.048 .154 -.057 .019 .233 fe 1 .108 .174 .458* -.154 -.167 -.335 -.230 -.128 -.165 mn 1 .085 -.062 .417 .310 -.314 -.083 .378 .015 zn 1 .067 -.037 .246 -.306 -.378 .303 -.553** cu 1 -.219 .082 -.295 -.334 .052 -.501* ca 1 .727** -.051 .434* .801** .252 mg 1 -.012 .009 .914** -.233 k 1 .281 -.169 .495* na 1 .083 .559** cec 1 -.335 pbs 1 mulugeta et al. east african journal of sciences volume 12 (1) 11-28 24 pedon1, 2,5, 6, and 8 were situated within the altitudinal range of 2,400 – 2,600 meters above sea level; and had a shallow depth with gravelly subsurface. the pedons had <20% (by volume) fine earth, averaged over a depth of 75cm from the soil surface. the effective depths of pedons 1, 5, and 8 were <25 cm, whereas that of pedons 2 and 6 were 80 and 60 cm, respectively. the soils of these pedons are categorized under leptosols according to wrb (fao, 2014). the pedons also revealed absence of duric or gypsic horizons, dominated by sandy clay loam textural class. hence, these soils were grouped under mollic leptosols (eutric) in accordance with the wrb classification system. table 8. diagnostic horizons, properties and soil types of muger sub-watershed. pedon diagnostic horizon d ia g n o st ic p ro p e rt ie s soil type surface subsurface u-01 mollic mollic leptosols (eutric) u-02 mollic mollic leptosols (eutric) m-03 nitic rhodic nitisols (haplic) m-04 mollic vertic vertic pellic vertisols (grumic) m-05 mollic mollic leptosols (eutric) m-06 mollic mollic leptosols (eutric) l-07 mollic vertic vertic pellic vertisols (grumic) l-08 mollic mollic leptosols (eutric) note: u = upper; m = middle; l = lower figure 3. soil map of the study area. 4. conclusion soils of muger sub-watershed, central ethiopia, showed variability in distribution, which were conditioned by topographic features. the studied soils were formed from an arero group of lower complex archean volcanic rock dominantly basalt parent material. topography influenced the soil formation, whereby the soils in the higher slope positions were developed from in situ weathering of the parent material whereas continuous deposition of materials from the upper slope resulted in the development of different soil types in the lower slope positions. consequently, three soil types, rhodic nitisols (haplic), pellic vertisols (grumic), and mollic leptosols (eutric) were identified. the results revealed different degrees of limitations, potential and management requirements, the consideration of which is fundamental for sustainable use of soil resources. the results of the study have demonstrated that the major limitations for augmenting agricultural production on a sustainable basis are low levels of organic carbon, total nitrogen, zinc, calcium, potassium, and shallow soil depth. thus, integrated soil fertility management should be employed to manage the cation balances and build up soil organic matter, as it influences soil physical, chemical, and biological qualities. in general, the observed relationships between features of landscape, soil characteristics and soil types will help to advance soil-landscape relations in the study area, and show a less costly way of acquiring soil formation. conflict of interests the author(s) have not declared any conflicts of interest. 5. acknowledgments the authors are grateful to arba minch university for facilitating the study; international developed agency for swedish agricultural research and economic cooperation with developing countries (sida/sarec) as well as ethiopian ministry of education for providing the first author with the required financial supports to do the research. 6. references abayneh esayas. 2005. characteristics, genesis and classification of reddish soils from sidamo, ethiopia. doctoral dissertation, university of putra, malaysia. ahn, p. m. 1993. tropical soils and fertility use. longman group uk limited, uk. ashaye, t. y. 1969. sesquioxides status and particle size distribution in twelve nigeria soils derived from sand stones. african soils, 14: 85-96. ashenafi ali, abayneh esayas and sheleme beyene. 2010. characterizing soils of delbowegene watershed, wolaita zone, southern ethiopia for planning appropriate land management. journal of soil science and environmental management, 1 (8): 184-199. basanta singh, t., nandini devi, k., bijen kumar, y., bishworjit, n., nongdren khomba singh, l. and athokpam, h. s. 2013. characterization, and evaluation for crop suitability in lateritic soils. african j. agricultural research, 8 (37): 4628-4636. basava, r. d., naidu, m. v. s., ramavatharama, n., venkalah, k., rama rao, g. and reddy, k. s. 2005. characterization, classification and evaluation of soils in chandragirimandal of chittoor district, andhra pradesh. agropedology, 15: 55-62. bashour, i. i. and sayegh, a. h. 2007. methods of analysis for soils of arid and semi-arid regions. mulugeta et al. soil characterization and classification of soil of muger watershed 25 food and agriculture organization of the united nations. rome, italy. beernaert, f. 1990. simple and practical method to evaluate analytical data of soil profiles. maputo, mozambique. pp 145-150. black, g. r. and hertge, k. h. 1986. bulk density. pp. 1: 377-382. in: klute, a. 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(ed.). handbook of soil science. crc press, boca raton. skopp, m. s. 2002. physical properties of primary particles. crc press. llc. tekalign, t. 1991. soil, plant, water, fertilizer, animal manure and compost analysis. working document no. 13. international livestock research center for africa, addis ababa, ethiopia. mulugeta et al. soil characterization and classification of soil of muger watershed 27 undp (united nations development programme). 2014. ethiopia: quarterly economic brief: third quarter, 2014. van reeuwijk, l. p. 1993. procedures for soil analysis.4th edition. international soil reference and information center, the netherlands. verma, s. and jayakumar, s. 2012. impact of forest fire on physical, chemical and biological properties of soil: a review. proceedings of the international academy of ecology and environmental sciences, 2 (3):168-176. wakene, n. and heluf, g. 2004. the impact of different land use systems on soil quality of western ethiopia alfisols. international research on food security: natural resource management and rural poverty reduction through research for development and transformation. deutcher tropentage-berlin 5-7 october, 2004. pp. 1-7. walkley, a. and black, c. a. 1934. an examination of the degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method. soil science, 37: 29-38. wijntje-bruggeman, h. y. 1984. provisional soil association map of ethiopia (1: 2,000,000). field document 6. assistance to land use planning project. ministry of agriculture. addis ababa, ethiopia. mulugeta et al. east african journal of sciences volume 12 (1) 11-28 28 east african journal of sciences (2018) volume 12 (2) 111-126 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: abrahamgdr@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) effect of integrating variety, seed treatment, and foliar fungicide spray timing on managing common bean anthracnose at bako, western ethiopia abraham negera*1 and mashilla dejene2 1oromia agricultural research institute, bako agricultural research center p.o. box 03, bako, ethiopia 2school of plant sciences, haramaya university, p.o. box 138, dire dawa, ethiopia abstract: bean anthracnose [colletotrichum lindemuthianum (sacc. and magn.) lams.-scrib] is one of the major diseases of common bean (phaseolus vulgaris l.), and causes huge yield losses in western ethiopia. the research was conducted at bako during 2014 main cropping season with the objectives to: 1) assess the efficacy of seed treatment and foliar fungicide spray timing; 2) determine the effect of integrated use of common bean varieties, seed treatment and foliar fungicide spray timing on anthracnose severity, yield and yield components; and 3) assess the economic feasibility of the treatments. the treatments consisted of three bean varieties (awash melka, awash-1 and mexican 142), two levels of seed treatment (thiram-treated at the rate of 5 g kg-1 seed and non-treated) and four foliar spray timing with tebuconazole at the rate of 350 ml ha-1 (at the fifth trifoliate, flowering, pod setting stages and unsprayed control). the experiment was laid out as a randomized complete block design (rcbd) in a factorial arrangement and replicated three times per treatment. disease parameters were assessed from 18 pre-tagged plants per plot; yield components were assessed from ten randomly pre-tagged plants; seed yields were recorded from plants in the three central rows in each plot. variety, seed treatment, and foliar spray timing interacted significantly (p  0.05) to influence foliage and pod disease severity index, area under the disease progress curve (audpc), infected pod per plant and seed yield. awash-1, without seed treatment and without foliar spray, showed the highest (86.0%) foliage severity and the highest (71.32%) pod severity with calculated audpc values of 2771.19 and 1150.25%-days for leaf and pod, respectively. mexican 142 from treated-seed and sprayed with tebuconazole at the fifth trifoliate stage produced the highest (2354.074 kg ha-1) seed yield, followed by awash-1 (2239.76 kg ha-1) from non-treated seed and sprayed starting at the flowering stage. the highest marginal rates of return of 3071 and 2568% were calculated for awash-1 without seed treatments but sprayed at flowering and pod setting, respectively, followed by awash melka (1962%) that was sown without seed treatment but sprayed at the flowering stage. therefore, awash-1 and awash melka without seed treatment and spraying with tebuconazole at the flowering stage resulted in the optimum yields of the crop, indicating that these treatments could be practiced as the most effective management measures against common bean anthracnose for sustainable production of the crop in the study area and elsewhere with similar agroecologies. keywords: area under the disease-progress curve (audpc); [colletotrichum lindemuthianum (sacc. and magnus) lams.-scrib]; phaseolus vulgaris l.; foliar spray timing seed treatment 1. introduction common bean (phaseolus vulgaris l.) is an important legume crop in the daily diet of more than 300 million of the world’s population (hadi et al., 2006). it has been rated as the second most important source of human dietary protein and the third most important source of calories of all agricultural commodities produced in eastern africa (pachico, 1993). common bean production in the central rift valley of ethiopia contributes to about 60% of the total common bean production in the country (aleligne, 1990). common bean is grown usually as mixed varieties in most of southern, eastern, and western parts of the country (mohammed and somsiri, 2005). the yields of common beans are about three times as high in developed countries, such as usa and canada, compared to the developing countries (porch et al., 2013). the national average yield of common bean in ethiopia is low and it was estimated at 1.41 t ha-1 in 2015/2016 cropping season (csa, 2016); seed yields of improved varieties on research fields in ethiopia ranged from 2.5 to 3.0 t ha-1 (eppa, 2004). there are various production constraints that contribute to the low yields of common bean in the country. diseases are known to be the major factors that, directly or indirectly, affect the production of the crop. the major diseases that are currently threatening common bean production in ethiopia include anthracnose [colletotrichum lindemuthianum (sacc. and magnus) lams.-scrib], rust (uromyces appendiculatus f. strauss), common bacterial blight (xanthomonas axonopodis pv. phaseoli), halo blight (pseudomonas syringae pv. phaseolicola), angular leaf spot mailto:abrahamgdr@gmail.com abraham and mashilla east african journal of sciences volume 12 (2) 111-126 112 (phaeoisariopsis griseola sacc. ferr), ascochyta blight (ascochyta phaseolorum sacc.) and bean common mosaic virus. anthracnose, rust, angular leaf spot and common bacterial blight are more important than other common bean diseases and are widely distributed, while the rest are much more restricted in specific growing areas in their distribution (habtu, 1987; habtu and abiy, 1995; habtu et al., 1996; odogwu et al., 2016). bean anthracnose is the most serious disease of common bean in the cool weathers in latin america and africa. in these parts of the world, the field losses ranged from 90 to 100% due to seedling, leaf, stem and pod infection under climatic conditions favorable to the disease (nyvall, 1989; padder and sharma, 2017). the infected seeds are the most important means of dissemination of colletotrichum lindemuthianum (c. lindemuthianum), which explains its worldwide distribution (allen et al., 1996). the crop is vulnerable to the pathogen at all stages of growth, from seedling to maturity, depending on the prevailing environmental conditions that favor initiation and further development of the pathogen. the disease causes an estimated common bean yield loss of 63-100% in ethiopia (tesfaye, 1997; kutangi et al., 2010; amin et al., 2014), but there is variation from one region to another. for instance, 42.4% yield loss was reported for haramaya district (amin et al., 2013) and 11.9% for bako area from infection of free seeds and 20% from infected seeds (mohammed and somsiri, 2005). also the planting value of harvested seed is reduced due to decreased germination and poor quality (singh and schwartz, 2010). management strategies used to minimize seed-borne infection due to c. lindemuthianum in the seed production fields include cultural, host resistance, biological, and chemical protection methods. although the infected seeds are the most important means of dissemination of c. lindemuthianum (allen et al., 1996), the pathogen affects the crop at all stages of growth. therefore, it is necessary to understand the interaction between common bean and the pathogen at different developmental stages of the crop to design sustainable disease management strategies. moreover, integrated disease management is the most recommended option for such diseases in which infection due to the fact that pathogen occurs starting from the seed to all growth stages of the crop, and due to the high diversity of the pathogen (allen et al., 1996). however, integrating host resistance, seed treatment and foliar application of fungicides at different growth stages of the crop was not studied well in ethiopia. therefore, this study was conducted with the objectives to elucidating the effect of integrating common bean variety, seed treatment, and foliar fungicide spray timing on the severity of common bean anthracnose and yield and yield components of the crop as well as to assess the economic feasibility of the different treatment combinations. 2. materials and methods 2.1. description of the study site the study was conducted at bako agricultural research center (barc) in western ethiopia during the 2014 main cropping season. bako agricultural research center (barc) has warm, humid climate with 54 years mean minimum, maximum and average temperatures of 13.3, 28.0 and 20.6 oc, respectively, and 48 years mean relative humidity of 63.55% (barc, 2014). the averages of seven days interval rainfall and temperature during the production period are depicted hereunder (figure 1). figure 1. weather data of bako during 2014 cropping season a. experimental materials i. common bean varieties the three malkasa agricultural research center released white seed-canning type common bean varieties, namely mexican 142, awash 1 and awash melka, released in 1973, 1990 and 1998/99, respectively, were used in this experiment. the varieties have been recognized to possess different susceptibility levels, viz. mexican 142 is moderately susceptible, and awash-1 and awash melka are susceptible and tolerant, respectively, for the disease anthracnose caused by c. lindemuthianum (sacc. and magnus) lams.(kutangi, et al., 2010; barc, 2013). ii. fungicides the fungicide used in seed treatment is a protective fungicide, commonly known as thiram 75 wp and chemically known as tetramethyl thiuram disulfide. the broad spectrum systemic fungicide tebuconazole 430 sc, commonly known as orius 25 ew, was used for foliar spray to manage common bean anthracnose. b. treatments and experimental design the treatments consisted of four spray application timing of foliar fungicide (tebuconazole, syn. folicur) at the rate of 350 ml ha-1 (at the fifth trifoliate, flowering, pod setting stages and unsprayed control), two rates of seed treatment with the fungicide thiram (thiramtreated at the rate of 5 g kg-1 seed and non-treated) and three common bean varieties (mexican 142, awash-1 abraham and mashilla integrated variety, seed treatment, and fungicide on common bean 113 and awash melka). the experiment was laid out as a randomized complete block design (rcbd) in a factorial arrangement and replicated three times per treatment. the treatments were assigned to each plot randomly. the experimental area was divided into 24 plots and each plot had size of 4 m x 2 m (=8 m2) with five rows each at the spacing of 40 cm apart and 10 cm between plants. the plots and adjacent replications were spaced at the distances of 1.0 and 1.5 m, respectively. recommended amount of 100 kg ha-1 diammonium phosphate (dap) fertilizer (consisting of 46 kg p2o5 and 18 kg n ha-1) was applied once at planting. 2.4. seed treatment the seeds of all common bean varieties (mexican 142, awash-1 and awash melka) were treated with the systemic fungicide tebuconazole at the rate of 5 g kg-1 seed 24 hours before sowing. the untreated seeds from all common bean varieties served as control or check treatments. 2.5. tebuconazole foliar fungicide application tebuconazole 430 sc (orius 25 ew) was applied at a rate of 350 ml ha-1 with water spray volume of 100 l ha1 at different growth stages of the crop, i.e. from vegetative stage (5th trifoliate stage), flowering (1st flower stage) to the beginning of pod setting using a knapsack sprayer having 20 liters capacity. control (check) plots were sprayed with pure water in the same manner with that of fungicide sprayed plots to prevent differences among plots due to variation in moisture. the fungicidesprayed plots were treated three times at a 10-day interval starting from the above mentioned growth stage of the crop onwards. the timing of application of the fungicide spray varied according to the growth stage of the crop varieties from the 5th trifoliate stage to the start of pod setting. fungicide drift between and among the treatments were prevented by covering the plots with plastic sheets. 2.6. data collection the first fungicide spray was applied 46 days after sowing. seven days after the start of fungicide spraying, anthracnose severity assessment was started. anthracnose severity was assessed from 18 pre-tagged plants of from three central rows in each plot every week. evaluation of disease severity was performed using a 1 to 9 grade disease scale proposed by schoonhoven and pastor-corrales (1987), where: 1 = leaf with no visible symptoms; 2 = few isolated small lesions on mid-veins in the lower leaf surfaces; 3 = a higher frequency of small lesions on mid-veins in the lower leaf surfaces; 4 = lesions in the mid-vein and occasionally in secondary leaf veins; 5 = many small lesions scattered on midand secondary veins; 6 = many small lesions as described in grade 5 in the lower and upper leaf surface; 7 = large lesions scattered over the leaf blade; 8 = many large, coalesced lesions accompanied by tissue breakdown and chlorotic or abscised leaf; and 9 = severely diseased or dead leaf. then the anthracnose severity grades were converted, for further analyses into percentage severity index (psi) using the formula developed by wheeler (1969) as follows: (1) the area under disease progress curve (audpc) and growth curve models were developed for the disease progress data. audpc-values were calculated for each plot using the formula stated by campbell and madden (1990). ….(2) where: n = represents the total number of assessment times, ti is the time of the ith assessment in days from the first assessment date, and xi is percentage of disease severity at ith assessment. disease progress in time was studied by recording the severity of anthracnose at a 7-day interval right from appearance of first disease symptoms till the maturity of the crop in different varieties and treatments. therefore, disease progress rate was calculated for each plot using the following formula (van der plank, 1963): (3) where: dpr = disease progress rate, and y = disease severity yield and yield component data, including number of pods per plant, number of infected pods per plant, number of seeds per pod, hundred seed weight and seed yield (kg ha-1) were measured from the three middle rows. the number of pods per plant was determined as the average number of pods from ten randomly pretagged plants and the number of infected pods per plant was determined from the same plants as the average number of anthracnose-infected pods. the average number of seeds per pod was counted at harvest time from ten randomly pre-tagged plants, in ten randomly taken pods per plant. the seeds were sun-dried and weighed. hundred seeds having the symptom of anthracnose infection were weighed and registered separately for all treatments. the weights of hundred seeds were measured from seeds randomly taken from the total seeds harvested from each plot. the seed yield per hectare in kilogram was estimated from seed yields of each plot (after adjusting to 10% seed moisture content) obtained from the three central rows. abraham and mashilla east african journal of sciences volume 12 (2) 111-126 114 2.7. data analysis all the disease, yield and yield component data were subjected to analysis of variance (anova) using general linear model (glm) procedure of sas statistical version 9.2 software (sas, 2009). the least significant difference (lsd) test was used to separate differences in treatment means of main factor effects where significant variation was observed at 5% probability level. lsmeans for significantly different interaction effects were separated by sas model plglm800 (p=0.05) using duncan’s multiple range test (dmrt). the cost and benefit of each treatment was estimated from the marginal rate of return (mrr) that was computed by considering the variable cost available in the respective treatment. variable costs included chemical costs and labor expenses for application of fungicides both for seed and foliar treatment. the yield and economic data were collected to compare advantages of seed treatment and foliar application in different treatments. economic data encompassed input cost that varied, including cost for chemicals and labour during production time. based on the data obtained, cost-benefit analysis was performed using partial budget analysis, which is a method of organizing data and information about the cost and benefits of various agricultural alternatives (cimmyt, 1988). before marginal analyses were carried out, dominance analysis was conducted for the treatments. a dominance analysis was thus carried out by first listing the treatments in order of increasing costs that varied. any treatment that has net benefits that are less than or equal to those of a treatment with lower costs that varied is dominated and it was eliminated from further consideration (cimmyt, 1988). 3. results and discussion 3.1. bean leaf anthracnose severity anthracnose disease appeared on bean leaves 46 days after sowing. consistent with this observation, hirpha and salvaraji (2016) reported that the disease appeared 48 days after sowing common bean at ambo. the interaction effect of seed treatment with foliar fungicide spray times indicated that plots without any fungicide treatment had high psi throughout the disease assessment periods that ranged from 27.89% at initial assessment to 66.17% at terminal disease assessment period. in a similar study, amin et al. (2013) reported that seed treatment with mancozeb followed by carbendazim foliar spray, and seed treatment with carbendazim followed by foliar spray with carbendazim significantly reduced bean anthracnose severity (table 1). the integrated effect of variety, seed treatment and foliar spray time generally exhibited significant (p ≤ 0.05) difference in psi all over the disease assessment periods (table 2, 3). all varieties, regardless of seed treatment, sprayed at the third leaf stage of the crop exhibited lower disease severity till 74 days after planting (das); however, they were infected by anthracnose after these days. the highest (38.8-86%) significant percentage severity index (psi) was recorded for awash1 variety without seed treatment, followed by no-foliar fungicide spray at all disease assessment periods. the combined treatment effect on all common bean varieties, and with and/or without seed treatment but sprayed at flowering stage showed the lowest psi at the final disease assessment period (table 3). 3.2. anthracnose severity on pod the percent severity index (psi) of pods was significantly (p ≤ 0.05) affected by integrated anthracnose management (tables 2 and 4). significant (p  0.01) variation was observed on pod percent severity index due to variety * seed treatment * foliar application time at all disease assessment periods (table 4). plots sown with seed-treated awash melka variety and sprayed with the fungicide at flowering stage of the crop resulted in significantly the lowest (20.9%) psi in comparison to non-treated seeds of awash-1 without foliar spray, which exhibited the highest (71.3%) pod psi. seed treatment and foliar spray at flowering stage resulted in 68, 53 and 37% pod severity reduction over the control plots, i.e. non-treated seeds and without foliar spray on each of awash-1, awash melka and mexican 142, respectively. control plots of awash-1 variety showed higher pod psi than the other varieties at all assessment periods; however, psi was lower for awash melka variety than for the other two varieties. abraham and mashilla integrated variety, seed treatment, and fungicide on common bean 115 table 1. the effect of common bean varieties integrated with foliar fungicide spray times on percentage severity index and audpc at bako in 2014 main cropping season. treatment component (variety x foliar spray time) anthracnose percent severity index (psi, %) audpc(%days) 53 das 60 das 67 das 74 das 81 das 88 das variety: foliar spray: awash melka 5th trifoliate 19.564 19.564 19.564c 22.826 f 31.236 ef 34.475 d 603.858 fg flowering 20.864 22.130 22.301c 22.568 f 23.075 g 23.639 f 514.558 fg pod setting 23.001 27.817 29.771b 32.156 de 33.210 ef 33.463 d 908.848 de control 25.570 33.263 35.900b 49.216 b 55.964 b 63.062 b 1674.383 b awash-1 5th trifoliate 20.174 20.174 21.619c 29.716 e 35.839 de 42.399 c 795.782 ef flowering 20.013 20.264 20.687c 21.628 f 22.840 g 24.753 ef 476.389 g pod setting 25.207 33.087 34.697b 36.783 cd 42.067 cd 42.362 c 1248.765 c control 29.676 38.117 49.125a 56.834 a 65.537 a 71.702 a 2071.193 a mexican 142 5th trifoliate 20.275 20.549 20.726c 23.141 f 27.823 fg 31.314 de 573.971 fg flowering 20.275 21.478 22.559c 23.050 f 24.487 g 26.072 ef 537.963 fg pod setting 26.169 33.211 34.455b 41.062 c 45.791 c 47.466 c 1360.391 c control 21.644 27.403 31.266b 35.638 cd 40.817 cd 45.881 c 1113.735 cd lsd (0.05) ns ns 6.235 5.342 6.280 7.088 296.620 se(±) 1.745 2.249 2.190 1.877 2.206 2.490 104.199 seed treatment: foliar spray: treated 5th trifoliate 20.062 20.184 d 21.029c 26.935 c 31.740 d 35.507 c 678.395 c flowering 20.338 21.079 d 21.702c 22.275 d 22.906 e 23.666 d 494.753 c pod setting 25.611 33.229ab 34.252b 36.969 b 40.137 c 40.984 c 1223.800 b control 23.368 27.388 c 31.131b 40.616 b 46.332 b 54.260 b 1290.775 b untreated 5th trifoliate 19.947 20.007 d 20.244c 23.520 cd 31.526 d 36.618 c 637.346 c flowering 20.430 21.503 d 21.996c 22.556 cd 24.029 e 25.977 d 524.520 c pod setting 23.974 29.514bc 31.696b 36.365 b 40.575 c 41.210 c 1121.536 b control 27.893 38.468 a 46.396a 53.843 a 61.880 a 66.170 a 1948.765 a lsd (0.05) ns 5.227 5.091 4.362 5.127 5.787 242.189 se(±) 1.425 1.836 1.788 1.532 1.801 2.033 85.078 note: means followed by the same or no letter within a column are not significantly different from each other at 0.05 probability level, dmrt test. abraham and mashilla east african journal of sciences volume 12 (2) 111-126 116 table 2. mean squares from analysis of variance for disease parameters of bean anthracnose as influenced by variety, seed treatment and foliar fungicide spray time. source df foliage psi dpr pod psi foliage audpc 53 das 88 das 60 das 88 das 67 das 88 das model 25 51.639** 666.053 ns 0.00202** 0.00075** 2182.58** 97114.93** 856224.40** variety (a) 2 20.567 ns 412.740 ns 0.00007 ns 0.00056** 2661.17** 145442.83** 454624.48** seed treatment (b) 1 9.229 ns 272.314 ns 0.00146 ns 0.00043** 555.56 ns 180505.14** 333472.22* foliar spray time (c) 3 153.564** 3927.266 ns 0.01184** 0.00463** 1172.86** 466359.58** 4626224.11** rap 2 27.700 ns 53.886 ns 0.00011 ns 0.00006 ns 12587.99** 8253.96 ns 111647.97 ns a x b 2 40.069 ns 147.976* 0.00007 ns 0.00007 ns 550.99** 97430.62** 178710.21 ns a x c 6 31.362 ns 376.596** 0.00029 ns 0.00041** 294.92 ns 24083.90** 452835.87** b x c 3 31.695 ns 131.943** 0.00250** 0.00009* 727.04** 9577.74 ns 557813.01** a x b x c 6 60.188** 118.769* 0.00064 ns 0.00004 ns 12.003 ns 28799.64** 218840.96** error 46 18.268 37.196 0.00041 0.00002 137.250 5546.630 65144.56 total 71 mean 22.700 40.550 0.0262 0.0245 23.457 584.639 989.986 r2 60.570 90.680 72.29 94.76 89.63 90.490 87.72 note: *= significant at p≤0.05; ** = highly significant p≤0.01; ns: non-significant; psi= percentage severity index; dpr= disease progress rate and audpc= area under disease progress curve. table 3. interaction effect of variety x seed treatment x foliar fungicide spray time on anthracnose percentage severity index at different anthracnose assessment periods on foliage at bako in 2014 main cropping season. variety seed treatment foliar leaf severity index (%) audpc 53 das 60 das 67 das 74 das 81 das 88 das (%-days) awash melka treated trifoliate 19.657 c 19.657 g 19.657 h 25.464 g-j 32.453 35.762 f-i 648.87 fg flower 21.1670 bc 22.345 fg 22.516 d-h 22.701 ij 22.701 23.363 l 517.80 fg pod 23.142 bc 27.966 c-g 29.499 b-g 31.366 e-h 32.435 32.940 h-l 900.21 d-f non 27.490 b 34.153 bc 36.562 b 48.679 b 52.938 64.837 b 1668.62b untreated trifoliate 19.471 c 19.471 g 19.471 h 20.189 j 30.020 33.188 h-l 558.85 fg flower 20.560 bc 21.915 fg 22.086 e-h 22.434 ij 23.450 23.914 kl 511.32 fg pod 22.861 bc 27.667 c-g 30.043 b-f 32.946 efg 33.985 33.985 g-k 917.49 d-f non 23.650 bc 32.374 bcd 35.237 b 49.752 b 58.991 61.288 bc 1680.14 b mexican 142 treated trifoliate 19.838 c 20.204 fg 20.382 h 22.687 ij 26.957 27.885 i-l 536.52 fg flower 19.657 c 20.200 fg 21.420 f-h 21.594 ij 22.791 23.428 l 472.43 g pod 27.342 b 37.304 b 37.777 b 43.819 bc 49.079 50.877 de 1540.43 bc non 22.068 bc 23.053 efg 26.174 c-h 29.232 f-i 34.028 40.540 f-h 832.51 e-g untreated trifoliate 20.712 bc 20.893 fg 21.071 gh 23.594 ij 28.689 34.744 g-j 611.42 fg flower 20.893 bc 22.756 efg 23.697 d-h 24.507 hij 26.184 28.715 i-l 603.50 fg pod 24.995 bc 29.118 b-f 31.13 bcd 38.304 cde 42.503 44.055 efg 1180.35c-e non 21.220 bc 31.752 b-e 36.358 b 42.044 bcd 47.605 51.222 cde 1394.96 bc awash-1 treated trifoliate 20.691 bc 20.691 fg 23.049 d-h 32.656 efg 35.809 42.875 e-h 849.79 d-g flower 20.189 c 20.691 fg 21.169 gh 22.531 ij 23.227 24.206 kl 494.03 fg pod 26.349 bc 34.418 bc 35.481 b 35.722 def 38.898 39.135 fgh 1230.76 c-e non 20.545 bc 24.957 d-g 30.657 b-e 43.936 bc 52.030 57.404 bcd 1371.19 bc untreated trifoliate 19.657 c 19.657 g 20.189 h 26.776 g-j 35.868 41.923 e-h 741.77 fg flower 19.838 c 19.838 g 20.204 h 20.726 j 22.452 25.301 jkl 458.75 g pod 24.065 bc 31.757 b-e 33.914 bc 37.844 cde 45.236 45.590 ef 1266.77b-d non 38.808 a 51.277 a 67.593 a 69.733 a 79.044 86.001 a 2771.19 a se(±) 2.468 3.180 3.097 2.654 3.120 3.521 147.36 lsd (0.05) 7.025 9.053 8.817 7.555 ns 10.024 419.484 note: means followed by the same or no letter within a column are not significantly different from each other at 0.05 probability level, dmrt test abraham and mashilla integrated variety, seed treatment, and fungicide on common bean 117 3.3. area under disease progress curve (audpc) interaction of variety * foliar spray, and seed treatment * foliar spray showed significant foliage audpc (tables 1). however, the interaction effect of variety * seed treatment showed no significant difference. awash-1 sprayed at flowering showed the lowest (476.389%-days) foliage audpc of all the other variety * foliar spray interactions. however, the highest audpc of 2071.193 and 1674.383%-days were observed on the foliage of control plots of awash-1, and awash melka, respectively. this current result agrees with the findings of mohammed and somsiri (2005) who reported that the foliage audpc value was higher for the variety awash-1 than mexican 142. audpc was also significantly different among common bean varieties based on their reaction to the disease, in which the susceptible variety produced the highest foliage audpc, while the values were the lowest in resistant varieties (sharma et al., 2008). hirpha and selvaraj (2016) also indicated that foliar fungicide application reduced audpc value on every variety. foliage audpc calculated for plots from untreated seeds and not receiving any foliar fungicide sprays showed significantly (p≤0.05) highest (1948.765%days) values of all the rest seed treatment and foliar fungicide spray combinations. however, the lowest 494.753 and 524.52%-days foliage audpc values were calculated from plots sown with seeds treated and sprayed at flowering, and untreated seeds but sprayed at flowering, respectively. similar to the results of the current study, amin et al. (2013) reported that interaction of seed treatment with foliar fungicide sprays significantly differed in foliage audpc values; generally plots from treated-seeds and followed by spray with foliar fungicide had significantly reduced foliage audpc values. the combined effect of variety *seed treatment* foliar spray time showed highly significant (p  0.01) difference in the area under disease progress curve (table 2). the lowest most significant foliage audpc value (458.745%-days) was calculated from plots of the variety awash-1, without seed treatment and sprayed at flowering, followed by audpc values of 472.428 and 494.033%-days that resulted from plots sown with treated-seeds of mexican 142 and awash-1, respectively, and both sprayed at flowering (table 3). the highest foliage audpc value (2771.193%-days) was calculated from data recorded from non-seed treated and unsprayed awash-1, followed by audpc value (1680.144%-days) on awash melka, without seed treatment and unsprayed plots. the three-way interaction effects of variety, seed treatment, and foliar fungicide spray showed significant differences on pod audpc values (table 2 and 3). significantly the highest pod audpc value (1150.25%days) was calculated from plots sown with non-treated seeds of awash-1 without foliar spray, followed by audpc value (919.45%-days) on plots sown with non-treated seeds of mexican 142 without foliar spray. however, the lowest pod audpc value (435.06%days) was calculated from plots sown with treated seeds of awash melka and sprayed at flowering of the crop variety (table 3). thus, integrated disease management options, rather than using a single component strategy alone, proved to be a more effective disease management option for sustainable bean production than using a single tactic alone. 3.4. anthracnose progress rate on common bean varieties the interaction effect of variety with foliar fungicide spray, and seed treatment with foliar fungicide spray were significant from 67 das assessment period onwards; however, the interaction effect of seed treatment with foliar fungicide spray was not significantly (p ≤ 0.05) different at 60 das (table 2). the interaction effect of variety * seed treatment, and variety * seed treatment * foliar spray were not significant. variety with foliar fungicide spray interaction resulted in significantly higher (0.0643 unitsday-1) anthracnose progress rate on awash-1 variety at 67 das than the interaction effect of the same variety without foliar spray. awash melka variety sprayed at fifth trifoliate stage till 67 das and awash-1 at 60 das did not show any increase in disease progress rate (figure 2). the analysis of variance revealed the occurrence of higher disease progress rates, i.e. 0.0584, 0.0471 and 0.0310 units-day-1 at the final disease assessment period on the control plots of awash-1, awash melka and mexican 142 varieties, respectively, than the treated plots of each variety. the maximum protected plot of awash melka sprayed at flowering reduced anthracnose progress rate 11 times more than the plots under natural condition (non-sprayed control plots), while the maximum protected plots of awash-1 and mexican 142 varieties sprayed with tebuconazole at flowering reduced disease progress rate seven and three times, respectively, more than the plots of the same varieties under natural conditions, i.e. without any treatment (figure 4). generally, anthracnose progress rates at 74 das disease assessment period onwards were lower on all bean varieties sprayed with tebuconazole at flowering stages than the disease progress rates of all the interactions due to other treatment combinations (figure 3). seed treatment and foliar fungicide spray at flowering significantly reduced anthracnose progress rate eight times more than the anthracnose progress rate on plots sown with treated-seeds but without foliar fungicide spray, while foliar spray alone reduced anthracnose progress rate six times more than plots sown from nontreated seeds and unsprayed with tebuconazole. similar to the results of this study, amin et al. (2013) reported that disease progress rate was significantly affected by seed treatment and foliar fungicide spray interaction at haramaya. abraham and mashilla east african journal of sciences volume 12 (2) 111-126 118 table 4. interaction effect of varieties, seed treatment and foliar spray times on pod percentage severity index (psi) and audpc at bako in 2014 main cropping season. seed treatment foliar pod anthracnose severity index (%) audpc (%-days) 67 das 74 das 81 das 88 das awash melka: treated trifoliate 19.47 g 19.47 g 22.28 ij 22.59 ij 439.44 j flower 19.84 g 20.89 fg 20.89 j 20.89 j 435.06 j pod 20.90 fg 21.24 fg 22.20 ij 22.20 j 454.88 j non 25.03 cde 37.48 bc 39.12 b-e 39.37 cd 761.71 cde untreated trifoliate 19.47 g 19.47 b 21.54 j 22.53 ij 434.06 j flower 19.47 g 21.58 fg 24.21 hij 24.51 g-j 474.50 ij pod 20.55 fg 21.26 fg 22.30 ij 22.30 ij 454.91 j non 21.54e fg 30.81 d 33.09 d-g 33.38 de 639.53 efg mexican 142: treated trifoliate 19.47 g 21.22 fg 24.17 hij 24.74 f-j 472.45 ij flower 19.47 g 19.84 g 21.61 j 22.30 ij 436.34 j pod 25.46 cd 26.65 def 30.34 f-i 30.34 e-g 594.24 f-i non 23.88 def 29.15 de 31.53 e-h 31.53 ef 618.61 fgh untreated trifoliate 19.47 g 21.57 fg 26.96 g-j 29.76 e-h 512.04 hij flower 20.53 fg 22.87 fg 26.77 g-j 27.05 e-j 513.97 hij pod 22.44 d-g 24.75 efg 27.08 g-j 27.34 e-j 536.96 g-j non 33.88 b 44.34 a 46.30 b 47.54 b 919.45 b awash-1: treated trifoliate 19.84 g 20.53 g 22.86 ij 26.36 f-j 465.40 j flower 19.47 g 20.85 g 21.91 j 22.28 ij 445.44 j pod 19.47 g 21.22 fg 22.56 ij 22.90 hij 454.76 j non 27.81 c 37.21 bc 45.35 bc 46.06 bc 836.48 bc untreated trifoliate 20.56 fg 32.30 cd 37.33 c-f 42.45 bc 707.90 def flower 20.56 fg 20.56 g 24.61 hij 29.23 e-i 490.42 ij pod 25.86 cd 37.48 bc 40.84bcd 41.08 bc 782.53 cd non 41.09 a 42.04 ab 66.08 a 71.32 a 1150.25 a lsd (0.05) 3.655 5.847 7.976 6.935 122.403 se(±) 1.284 2.054 2.802 2.436 42.999 note: according to dmrt, means followed by the same letter(s) within a column are not significantly different at 5% probability level. figure 2. interaction effect of seed treatment with foliar fungicide spray on anthracnose progress rate at bako in 2014 main cropping season. figure 3. interaction effect of variety with foliar fungicide spray on anthracnose progress rate at bako during 2014 main cropping season. abraham and mashilla integrated variety, seed treatment, and fungicide on common bean 119 3.5. effect of variety, seed treatment, foliar spray and their interaction on yield and yield components 3.5.1. pod per plant, infected pod per plant, and seed per pod main effects of variety, seed treatment and foliar fungicide spray showed highly significant (p ≤ 0.01) differences on the number of pods per plant and infected seed per pod. however, pod infection per plant was significantly (p ≤ 0.01) affected by variety and foliar fungicide spray (table 5). the highest (16.958) mean number of pods per plant was observed for the variety awash-1, while awash melka and mexican 142 produced lower pod number than awash-1, i.e. 13.542 and 14.875 pods per plant, respectively. also, plots sown with treated-seeds produced significantly higher (17.056) pod mean number per plant than plots sown with untreated seeds. plots sprayed with foliar fungicide at the fifth trifoliate stage gave significantly higher number of pods per plant than the control plots, followed by plots sprayed at flowering stage (figure 4). similar to this result, amin et al. (2014) reported that the number of pods per plant was significantly different from foliar fungicidesprayed plots and plots sown with bioagent-treatedseeds along with non-spray fungicide. but, contrary to this finding, amin et al. (2013) reported that the number of pods per plant was non-significant and did not differ from plots sown with treated-and untreatedseeds, and foliar sprayed and non-sprayed plots. figure 4. effect of variety, seed treatment and foliar spray on number of pods per plant and number of seeds per pod at bako in 2014 main cropping season. note: according to dmrt, means followed by the same letter(s) within a similar colored graphs are not significantly different at 5% probability level. table 5. mean squares of common bean morphological and yield related data parameters as influenced by integrated anthracnose management options at bako in 2014 main cropping season. source df mean squares (ms) values ip nsp pp model 25 1330.118** 0.298* 32.640** variety (a) 2 2329.542** 1.120** 73.789** seed treatment (b) 1 130.681 ns 0.405 ns 288.400** foliar spray (c) 3 6796.125** 0.323 ns 43.858** rep 2 32.042 ns 0.058 ns 0.691 ns a x b 2 433.681** 0.238 ns 1.934 ns a x c 6 433.986** 0.332 ns 29.659** b x c 3 132.384 ns 0.141 ns 15.937* a x b x c 6 690.384** 0.139 ns 2.907 ns error 46 77.998 0.163 4.494 total 71 r2 90.26 49.9 79.788 mean 31.625 5.500 15.054 note: df = degree of freedom; ip = infected pod per plant; nsp = number of seeds per pod and pp = pod per plant; ** highly significant at p ≤ 0.01; * significant at p ≤ 0.05; ns= non-significant. abraham and mashilla east african journal of sciences volume 12 (2) 111-126 120 plots sown with treated-seeds of awash melka variety and sprayed with tebuconazole at flowering stage reduced pod infection by more than 93, 93 and 94% over the plots sown with untreated seeds and unsprayed awash-1 and mexican varieties and treatedseeds and non-sprayed awash melka varieties, respectively. (tables 5 and 7). pod infection significantly (p≤0.05) varied among common bean varieties even without any fungicide treatment. in this connection, awash melka variety without any seed treatment showed lower (38.67%) pod infection, while 75 and 71.3% pod infections were recorded for the varieties awash-1 and mexican 142 plots, respectively, that did not receive any fungicide treatment. pod infection on the susceptible common bean variety ranged from 45.60 to 55.95% during favorable environment for pathogens to cause disease development (hanan et al., 2009). 3.5.2. effect of integrated anthracnose management options on hundred seed weight of infection-free and infected-seeds combined effect of common bean variety with foliar fungicide spray significantly affected hundred infectedseed weight; however, combined effect of variety with thiram seed treatment, foliar fungicide spray with seed treatment, and integrated effects of variety with seed treatment with foliar fungicide spray resulted in nonsignificant difference in weights of hundred infectedseeds (table 6). the result indicated that awash-1 variety without foliar fungicide spray significantly lowered (10.9 g) 100 infected seed weight. however, the infected seeds of the variety awash melka sprayed at pod setting and mexican 142 variety sprayed at flowering showed higher hundred seed weight than that of awash-1 (table 6). 3.5.3. effect of integrated anthracnose management options on seed yield the two-way interaction of variety with seed treatment, variety with foliar spray, and seed treatment with foliar spray showed a significant difference in bean seed yield (table 6). plots sown with treated seeds of awash melka produced the highest significant seed yield (1912.750 kg ha-1) of all treatments. similarly, the highest, i.e. average seed yields (2096.493 and 2071.486 kg ha-1,) were obtained from bean plots sown with treated and untreated seeds and sprayed at flowering stage, respectively, whereas plots sown with non-treated seeds and non-sprayed with fungicide showed significantly lower (1049.354 kg ha-1) average seed yield, followed by the seed yield (1419.920 kg ha-1) from plots sown with treated-seeds and nonsprayed plots (table 6). consistent with the results of this study, amin et al. (2013) reported that the combined effect of benlate (benomyl) as a seed treatment and difenoconazole (score 250 ec) effectively reduced anthracnose severity and increased the yield per plot. mexican 142 sprayed at the fifth trifoliate stage, and awash-1 and awash melka sprayed at the flowering stage produced the highest respective seed yields of 2226.770, 2197.88 and 2149.62 kg ha-1 of all other treatment combinations of variety with foliar fungicide sprays. on the contrary, awash-1 without foliar fungicide spray produced the lowest (948.32 kg ha-1) seed yield. foliar fungicide spray at flowering stage increased seed yield of awash-1 variety by 56% over the unsprayed (control) plots (table 6). three-way interactions of variety, seed treatment and foliar spray significantly differed in seed yield among the treatment combinations (table 7). the seed yield obtained from plots sown with treated seeds of mexican 142 variety and sprayed at the trifoliate stage was the highest (2354.07 kg ha-1), followed by 2156, 2239.76 and 2175.99 kg ha-1 seed yields of awash-1 sown with treated and non-treated seeds and sprayed at flowering stage, and awash melka without seed treatment and sprayed at flowering stage, respectively. foliar spray at flowering stage alone increased seed yield by more than 67% for awash-1 variety over the control plots of the same variety (table 7). the minimum seed yield advancement by 38% was recorded from awash-1 plots sown with seed-treated but without foliar fungicide spray as compared with its own control plots of the three-way interaction combinations. abraham and mashilla integrated variety, seed treatment, and fungicide on common bean 121 table 6. two-way interaction effect of common bean varieties, seed treatment and foliar fungicide spray time on yield and yield related parameters at bako in 2014 main cropping season. components: pod per plant (no.) 100 infected seed wt (g) yield (kgha-1) seed treatment x variety: seed treatment: variety: treated awash melka 15.258 14.796 1912.750 a awash-1 19.233 12.834 1598.607 c mexican 142 16.675 13.013 1793.011 b untreated awash melka 11.575 13.769 1680.616 c awash-1 14.575 12.696 1595.708 c mexican 142 13.008 12.692 1606.930 c lsd (0.05) ns ns 101.289 se (±) 0.601 0.414 35.582 seed treatment x foliar spray seed treatment: foliar spray: treated 5th trifoliate 19.111 a 13.463 1945.010 b flowering 18.611 a 14.896 2096.493 a pod setting 14.289 bc 13.400 1611.066 d control 16.211 b 12.433 1419.920 e untreated 5th trifoliate 14.444 bc 13.457 1765.225 c flowering 12.244 de 13.907 2071.486 a pod setting 11.722 e 13.176 1624.940 d control 13.800 cd 11.670 1049.354 f lsd (0.05) 2.011 ns 116.958 se (±) 0.707 0.477 41.086 variety x foliar spray variety foliar spray awash melka 5th trifoliate 13.383 de 14.418 ab 1845.490 bc flowering 14.267 cd 14.488 ab 2149.616 a pod setting 11.467 ef 15.338 a 1810.926 bc control 14.550 cd 12.886 bcd 1380.701 de awash-1 5th trifoliate 19.333 a 12.269 cde 1493.092 d flowering 16.533 bc 15.221 a 2197.883 a pod setting 17.467 ab 12.671 cd 1749.335 c control 14.283 cd 10.899 e 948.319 f mexican 142 5th trifoliate 17.617 ab 13.693 abc 2226.770 a flowering 15.483 bcd 13.495 bcd 1904.471 b pod setting 10.083 f 11.854 de 1293.748 e control 16.183 bc 12.369 cde 1374.891 de lsd (0.05) 2.464 1.665 143.244 se (±) 0.865 0.585 50.320 note: means followed by the same or no letter (s) in the same column are not significantly different from each other at p≤0.05, dmrt abraham and mashilla east african journal of sciences volume 12 (2) 111-126 122 table 7. interaction effects of common bean variety, seed treatment and foliar fungicide spray time on infected pod per plant and seed yield at bako in 2014 main cropping season. variety seed treatment foliar spray infected pod per plant (%) seed yield (kg ha-1) awash melka treated trifoliate 13.000 hi 1918.983def flower 4.333 i 2123.245 bcd pod 9.333 hi 2035.057 bcd non 73.000 a 1573.716 hi untreated trifoliate 23.333 e-h 1771.998 fgh flower 9.667 hi 2175.986 abc pod 9.333 hi 1586.794 ghi non 38.667 d 1187.686 m mexican 142 treated trifoliate 28.667 d-g 2354.074 a flower 23.000 e-h 2010.231 cde pod 14.000 hi 1298.336 j-m non 31.000 def 1509.400 ij untreated trifoliate 30.000 def 2099.465 bcd flower 21.667 e-h 1798.711 efg pod 21.667 e-h 1289.160 klm non 71.333 ab 1240.383 lm awash-1 treated trifoliate 58.333 bc 1561.973 hi flower 33.667 de 2156.003 abc pod 18.000 f-i 1499.805 ijk non 57.000 c 1176.645 m untreated trifoliate 58.000 bc 1424.212 i-l flower 15.000 ghi 2239.762 ab pod 22.000 e-h 1998.865 cde non 75.000 a 719.992 n lsd (0.05) 14.515 202.578 se(±) 5.099 71.163 note: means followed by different letters within the same column are significantly different from each other and without letters are not significant at p≤0.05, dmrt. 3.6. cost-benefit analysis in bean anthracnose management partial budget analysis of marginal cost and marginal benefit depicted the highest (etb 32,775.67 ha-1) marginal benefit from mexican 142 plots sown with treated-seed and foliar fungicide-spray at the fifth trifoliate stage. however, awash-1 and awash melka varieties sown without seed treatment and sprayed with tebuconazole at flowering stage resulted in the highest marginal benefits of etb 31,562.57 and 30,644.20 ha-1, respectively. in addition, the marginal rates of return were calculated for the significant treatments under dominant analysis for comparison of the treatment cost/benefit of the treatments (table 8). for the variety awash-1, plots sown with untreated seeds and sprayed with fungicide at flowering stage exhibited that for every one etb incurred or invested on foliar fungicide spray at this stage additional etb 30.72 was obtained in return, followed by etb 25.69 from plots without seed treatment and sprayed with fungicide at pod setting. generally, awash-1 without seed treatment and with foliar fungicide spray at flowering stage resulted in a higher marginal rate of return than the other two common bean varieties, i.e. awash melka and mexican 142. similar to the findings of this study, hirpha and selvaraji (2016) indicted that awash-1 sprayed with fungicide had high marginal rate of return. on the other hand, sowing seeds after treating with the fungicide resulted in lower rates of return than sowing without treatment because additional costs were incurred for the purchase of fungicide for seed treatment (table 8). abraham and mashilla integrated variety, seed treatment, and fungicide on common bean 123 table 8. cost-benefit analysis of common bean production as influenced by anthracnose management options at bako in 2014 main cropping season. seed treatment foliar spray seed yield (kg ha-1) adj. seed yield (kg ha1) gross return (etb ha-1) marginal cost (etb ha-1) marginal benefit (etb ha-1) mrr (%) awash melka treated trifoliate 1918.98 1727.085 27633.4 1123.00 26510.36 -- flowering 2123.25 1910.921 30574.7 1123.00 29451.73 -- pod setting 2035.06 1831.551 29304.8 1123.00 28181.82 -- none 1573.72 1416.344 22661.5 433.00 22228.51 1183.79 untreated trifoliate 1772.00 1594.798 25516.8 690.00 24826.77 1119.43 flowering 2175.99 1958.387 31334.2 690.00 30644.20 1962.54 pod setting 1586.79 1428.115 22849.8 690.00 22159.83 -- none 1187.69 1068.917 17102.7 0.00 17102.68 0.00 mexican 142 treated trifoliate 2354.07 2118.667 33898.7 1123.00 32775.67 1328.06 flowering 2010.23 1809.208 28947.3 1123.00 27824.33 -- pod setting 1298.34 1168.502 18696.0 1123.00 17573.04 -- none 1509.40 1358.460 21735.4 433.00 21302.36 794.65 untreated trifoliate 2099.47 1889.519 30232.3 690.00 29542.30 1692.87 flowering 1798.71 1618.840 25901.4 690.00 25211.44 1065.21 pod setting 1289.16 1160.244 18563.9 690.00 17873.90 -- none 1240.38 1116.345 17861.5 0.00 17861.52 0.00 awash-1 treated trifoliate 1561.97 1405.776 22492.4 1123.00 21369.41 -- flowering 2156.00 1940.403 31046.4 1123.00 29923.44 -- pod setting 1499.81 1349.825 21597.2 1123.00 20474.19 -- none 1176.65 1058.981 16943.7 433.00 16510.69 1418.66 untreated trifoliate 1424.21 1281.791 20508.7 690.00 19818.65 1369.68 flowering 2239.76 2015.786 32252.6 690.00 31562.57 3071.69 pod setting 1998.87 1798.979 28783.7 690.00 28093.66 2568.95 none 719.99 647.9928 10367.9 0.00 10367.88 0.00 note: numbers written in columns of marginal rate of return (mrr) were treatments that showed significant differences in dominance analysis; average market price of bean etb 16 kg-1 4. conclusions the results of this study demonstrated that seed treatment and foliar spray of common bean plants with the contact fungixide thiram at the rate of 5 g kg-1 at flowering stage significantly reduced foliage anthracnose percent severity index (psi) by 54.26, 61.88 and 71.85% over the respective control plots of all three varieties tested (i.e., sown with non-treated seed without any earlier foliar sprays). the results revealed that mexican 142 common bean variety sown from treated-seed and sprayed with tebuconazole at the fifth trifoliate stage produced the highest (2354.074 kg ha-1) seed yield, followed by seed yield (2239.76 kg ha1) of the variety awash-1 sown from non-treated seed and sprayed at flowering stage. the economic analysis of the seed treatment with thiram at the rate of 5 g kg-1 seed indicated the highest (3071%) marginal rate of return (mrr) from the variety awash-1, followed by the same variety with mrr of 2568% without seed treatments but sprayed at flowering and pod setting stages, respectively, as well as awash melka (1962%) mrr without seed treatment but sprayed at flowering stage. awash-1 without seed treatment but sprayed at pod setting gave 2568% mrr, but 13% of the seeds had blemishes on their surfaces due to anthracnose resulting in low seed quality. therefore, awash-1 and awash melka without seed treatment but with a foliar spray treatment with tebuconazole at the rate of 350 ml ha-1 at the water spray volume of 100 l ha-1 at flowering stage that resulted in optimum yield and economic benefits of the crop are recommended as options for the management of common bean anthracnose. this implies that common bean farmers in the study area can enhance the productivity of common bean with the integrated cultivation of awash-1 and awash melka common bean varieties with the spray of the fungicide at the aforementioned rate. similarly, further research into seed treatment with different fungicides, testing the efficacies of more fungicides, application rates and frequencies in multilocations over seasons is desirable to design a consolidated integrated bean anthracnose management abraham and mashilla east african journal of sciences volume 12 (2) 111-126 124 options for sustainable common bean production in the study area and elsewhere that have similar agroecologies. future research should focus also on breeding for resistance by transferring resistance genes into improved market-type elite common bean varieties. 5. acknowledgements this paper was extracted from a master’s thesis, and haramaya university is acknowledged for facilitating the study. the authors thank the oromia agricultural research institute for funding the research project and bako agricultural research center for facilitating the mobilization of resources to accomplish the task. special thanks are also extended to all staff members of the pulse and horticulture research team at bako agricultural research center for their unreserved assistance in managing the field trials and data collection. 6. references aleligne k. 1990. farm survey and on-farm research in haricot bean in the middle rift valley of ethiopia. pp. 3-7. in: proceedings of a national workshop on research on haricot bean in ethiopia, addis ababa, ethiopia, 1-3 october, 1990. allen, d. j., ampofo, j. k. and wortmann, c. s. 1996. pests, diseases, and nutritional disorders of the common bean in africa. a field guide. centro international de agricultural tropical (ciat); technical center for agricultural and rural cooperation (tca), cali, (ciat publication no. 260). colombia. 132 pp. amin m., amare a. and nigussie d. 2013. effect of integrated management of bean anthracnose (colletotrichum lindemuthianum sacc. magn.) through soil solarization and fungicide applications on epidemics of the disease and seed health in hararghe highlands, ethiopia. journal of plant pathology and microbiology, 4: 1-7. amin, m., fitsum, s., selvaraj, t. and mulugeta, n. 2014. field management of anthracnose (colletotrichum lindemuthianum) in common bean through fungicides and bioagents. advanced crop science technology, 2: 124. doi: 10.4172/23298863:1000124. barc (bako agricultural research center). 2013. bako agricultural research center progress report of pulse crop team. barc (bako agricultural research center). 2014. bako agricultural research center meteorology station data of 1960 to 2014 years. campbell, c. l. and madden, l. v. 1990. introduction to plant disease epidemiology. john wiley and sons, new york. usa. 532 pp. cimmyt (centro internacional de mejoramiento de maíz y trigo). 1988. from agronomic data to farmer recommendations: answers to workbook exercises. international maize and wheat improvement center. mexico, df. v. 79 pp. csa (central statistical agency). 2016. agricultural sample survey for the 2015/2016 crop season. volume i. report on area and production of crops for private peasant holdings (meher season). statistical bulletin 584. fdre/csa, addis ababa, ethiopia. eppa (ethiopian pulses profile agency). 2004. ethiopian export promotion agency product development and market research directorate, ethiopia. 25 pp habtu, a. 1987. haricot bean diseases and their importance in ethiopia. ethiopian journal of agricultural science, 9: 968-973. habtu, a. and abiy, t. 1995. disease management in lowland pulses: progress and possibilities for an integrated approach. pp. 97-141. in: habtu a. (ed.). 25 years of experience in lowland crops research: proceedings of the 25thanniversary of nazareth agricultural research center workshop, 20-23 september 1995. nazareth, ethiopia. habtu, a., ivan, s. and zadoks, j. c. 1996. survey of cropping practices and foliar disease of common beans in ethiopia. crop protection, 15: 179-186. hadi, h., kazem, g. g., rahimzadeh, k. f., mostafa, v. and reza, s. m. 2006. response of common bean to different levels of shade of agronomy. journal of agronomy, 5: 595-599. hanan, i. m., mohamed, o. i. and mustafa, m. a. 2009. anthracnose disease in common bean (phaseolus vulgaris l.) in shambat, sudan. journal of agricultural science, 17: 118-130. hirpha, k. and selvaraj, t. 2016. evaluation of common bean cultivars and fungicide spray frequency for the management of anthracnose in ambo, west shewa zone, ethiopia. journal of biology, agriculture and healthcare, 6: 68-80. kutangi, e., farrow, a., mutuoki, t., gebeyehu, s., karanja, d., alemayehu f., sperlin, l., beebe, s., rubyogo, j. c. and buruchara, r. 2010. improving common bean productivity: an analysis of socioeconomic factors in ethiopia and eastern kenya. baseline report tropical legumes ii. centro international de agricultura tropical-ciat. cali, colombia. mohammed, y. and somsiri, s. 2005. seed transmission and epidemics of colletotrichum lindemuthianum in the major common bean-growing areas of ethiopia. kasetsart journal (natural science), 39: 34 – 45. nyvall, r. f. 1989. diseases of field beans (phaseolus vulgaris l.). pp. 215-249. in: field crop diseases handbook. springer, boston, ma. odogwu, b. a., nkalubo, s. t., mukankusi, c., paparu, p., patrick, r., kelly, j. and steadman, j. 2016. prevalence and variability of the common bean rust abraham and mashilla integrated variety, seed treatment, and fungicide on common bean 125 in uganda. african journal of agricultural research, 11: 4990-4999. pachico, d. 1993. the demand for bean technology. pp. 60-73. in: henry, g. (ed.). trends in ciat commodities 1993. ciat working document, cali-columbia. padder, b. a and sharma, p. n. 2010. assessment of yield loss in common bean due to anthracnose (colletotrichum lindemuthianum) under glass house conditions. research journal of agricultural sciences, 1: 184-188. porch, t. g., beaver, j. s., debouck, d. g., jackson, s. a., kelly, j. d. and dempewolf, h. 2013. use of wild relatives and closely related species to adapt common bean to climate change. agronomy 3: 433461. sas (statistical systems analysis). 2009. sas/stat ® version 9.2. sas institute inc. cary, north carolina 27513. schoonhoven, a. v. and pastor-corrales, m. a. 1987. standard system for evaluation of bean germplasm. international center for tropical agriculture (ciat), cali, colombia. 53 pp. sharma, p. n., sharma, o. p., padder, b. a. and kapil, r. 2008. yield loss assessment in common bean due to anthracnose (colletotrichum lindemuthianum) under sub-temperate conditions of northwestern himalayas. indian phytopathology, 6: 323-330. singh, s. p. and schwartz, h. f. 2010. breeding common bean for resistance to diseases: a review. crop science, 50: -223. tesfaye, b. 1997. loss assessment study on haricot bean due to bean anthracnose. pest management journal of ethiopia, 1: 69-72. van der plank, j. e. 1963. plant disease: epidemics and control. academic press, ny., usa. 349 pp. wheeler, b. e. j. 1969. an introduction to plant diseases. john wiley and sons, london. 374 pp. abraham and mashilla east african journal of sciences volume 12 (2) 111-126 126 east african journal of sciences (2018) volume 12 (2) 87-100 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: adugnawmintesnot@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) effect of altitude, shade, and processing methods on the quality and biochemical composition of green coffee beans in ethiopia adugnaw mintesnot1* and nigussie dechassa2 1jimma university, department of horticulture and plant science, p. o. box 307, jimma, ethiopia 2haramaya university, department of plant sciences, p.o. box 138, dire dawa, ethiopia abstract: there are growing demands for high quality coffee in the international market today. this has given coffee producing countries an impetus to increase the quality as well as the quantity of coffee they produce. for improving coffee quality and meet market demands, attention has been given to exploring genetic and environmental factors as well as agronomic and other coffee management practices. however, little information is available in ethiopia regarding effect of environmental factors such as altitude and coffee management practices such as shading and processing methods on the quality and biochemical composition of green coffee beans. this problem has constrained efforts being made in the country to further exploit the growing demands for quality coffees in the international market. therefore, a study was conducted during the 2010/11 main cropping season to determine coffee quality attributes as a function of altitude, shade, and processing methods. red ripe coffee cherries were handpicked from three coffee farms in south-western ethiopia located at altitudes of 1150, 1545 and 1802 meters above sea level, which represented lowland, midland, and highland coffee growing areas, respectively. the coffee cherries were obtained from both shaded and unshaded farms in each of the aforementioned coffee growing areas. the green coffee beans were subjected to both wet and dry coffee processing methods. a total of 36 coded samples (18 washed and 18 unwashed green coffee beans) with a moisture content of about 10.5% were subjected to cup and laboratory tests. coffee cup test was done according to the procedure of ethiopian commodity exchange (ecx) using 36 green coffee bean samples. contents of caffeine, trigonelline, and chlorogenic acids were determined using hplc/thermo. sucrose was determined using gc varian 3800. univariate analysis of variance and stepwise multiple regression analyses were conducted using spss 16 v2. the results revealed that coffee beans originating from the high altitude had significantly higher first grade and q1 grade points than coffee beans originating from the low and middle altitudes. unshaded and unwashed coffee grade was better than the washed and shaded coffee grade. caffeine content of the beans was affected neither by altitude, shading, nor by the processing method. shading affected only the content of bean caffeoylferuloylquinic acids (cfqa), which was found to be significantly higher for the unshaded coffee bean samples than the shaded coffee bean samples. contents of 4,5-dicaffeoylquinic acid (4,5-dcqa), feruloylquinic acids (fqa), and total chlorogenic acid (tcga) were significantly higher for coffee beans originating from the low and middle altitudes than those originating from the high altitude. similarly, coffee beans that originated from the low altitude had significantly higher contents of 3,4dicaffeoylquinic acid (3,4-dcqa), caffeoylferuloylquinic acids (cfqa), and trigonelline than coffee beans that originated from the high altitude. however, coffee beans that originated from the high and middle altitudes had significantly higher contents of chlorogenic acids, i.e., 3-caffeoylquinic (3-cqa) and 5-caffeoylquinic acid (5-cqa) than coffee beans that originated from the low altitude. the sucrose content of coffee beans that originated from the low latitude was significantly higher than the sucrose content of coffee beans that originated from middle and high altitudes. washed coffee beans contained significantly higher amounts of dicaffeoylquinic acid (4,5-dcqa), caffeoylquinic acid (5-cqa), chlorogenic acid (tcga), and trigonelline than unwashed coffee beans. however, unwashed coffee beans had significantly higher 3-caffeoylquinic (3-cqa) and caffeoylferuloylquinic acids (cfqa) contents than washed coffee beans. unwashed coffee beans had higher values for primary defect, secondary defect, odour, total-point and preliminary grade whilst washed coffee beans had better scores for acidity, body, and flavour attributes, which distinctly influence the ultimate taste profile of coffee origins. it is concluded that coffee bean quality attributes and contents of the associated chlorogenic acids improved in response to increased altitude under both shaded and unshaded conditions regardless of the type of processing method used. the results imply that growing coffee plants in the highlands and midlands rather than in the lowlands as well as washing the beans results in the production of coffee beans with high quality attributes and chlorogenic acid contents that could meet the rising international market demands for high cup quality. keywords: chlorogenic acid; final grade; high altitude; low altitude; mid altitude 1. introduction it is documented that arabica coffee has evolved in ethiopian montane high rainforests where live genetic diversity exists (aerts et al., 2012). this natural endowment helps ethiopia to grow coffee in a wide range of agro-ecologies (adugnaw, 2014; tadesse, 2015). adugnaw and nigussie east african journal of sciences volume 12 (2) 87-100 88 climate (temperature, light and water) and altitude, among others, are well known to play an important role through affecting temperature and availability of light and water in the ripening process of coffee cherries (decazy et al. 2003). the distribution of sunshine has also been identified as being a strong influential factor on flowering, bean expansion, and ripening. in line with this, the effect of shade was studied where some findings (vaast et al. 2005) revealed a decrease in coffee tree productivity in response to shading by about 20%, thereby reducing the alternate bearing pattern. the finding by vaast et al. (2005) also revealed positive effects of shade on bean size and composition as well as beverage quality by delaying berry flesh ripening by up to one month. in addition, the presence of shade trees, especially leguminous species, is known to improve soil fertility and enhance coffee plantation sustainability (soto-pinto et al. 2000). in traditional coffee production systems (adugnaw, 2014) with different levels of shade, however, berries ripen more slowly and yields are lower but green coffee beans and cup quality are superior (pohlan and janssens, nd). the flavour and aroma of coffee are believed to be affected by the presence of various volatile and nonvolatile chemical constituents such as proteins, amino acids, fatty acids, and phenolic compounds, and also by the action of enzymes on some of these components (gichimu et al., 2014). the role of biochemical composition of green coffee bean on cup quality was also reported by various researchers (ky et al., 2001; yigzaw et al., 2007; gichimu et al., 2014). a review by alonso-salces et al. (2009) revealed that all of the cinnamoyl derivatives play an important role in coffee quality, being responsible for its organoleptic properties. for instance, according to the aforementioned authors, the quality of the beverage increased as the chlorogenic acid (cga) content decreased. beverage bitterness is assumed to associate with caffeine content. higher elevations produce hard, dense beans (higher quality than soft beans) that are more sought-after than beans grown at lower elevations, because they have a higher concentration of sugars, which produce more desired and nuanced flavors (vaast et al., 2006; scott, 2015). several factors contribute to the increased concentration of sugars in coffee grown at high elevations. higher elevations impose harsh growing conditions like lower temperatures, bean maturation process thereby providing time for full physiological process and complex sugars to develop (scott, 2015). higher elevations are well drained which reduces the amount of water the coffee plants can take up, and, in turn, their cherries show high dry matter content (scott, 2015). moreover, as the rate of plant growth is slower at higher elevations the competition for growth factor remains low, and the pressure from pests and diseases is low. in fact, elevation does not just have a generic positive effect on a coffee’s quality. it may vary from region to region and, certain general flavors are associated with different elevations. according to scott (2015) for instance, at 762 meters coffee beverage will be soft, mild, simple, and bland; at 914 meters it will be sweet and smooth; at ~1,200 meters, it may have citrus, vanilla, chocolate, or nutty notes, and at ~1,500 meters, it might be spicy, floral, or fruity. the wet or the dry method of coffee processing strongly influences and determines the quality of green coffees, thereby establishing characteristic flavour differences. coffee beverages prepared from coffees obtained from the wet process are characterized by their full aroma and pleasant acidity while dry-processed coffees typically exhibit a so-called full body (mazzafera and robinson, 2000). guyot et al. (1996) reported small losses of caffeine (3%) during the soaking phase of the wet process as compared to the dry process. chlorogenic acid subgroups or individual chlorogenic acids were also proved to be affected by processing (guyot et al., 1995; leloup et al., 2005). in other work, trigonelline was found to be reduced by wet treatment (leloup et al. 2005). the composition of numerous metabolites, particularly that of amino acids (bytof et al. 2005), carbohydrates (knopp et al., 2006), and chlorogenic acids (balyaya and clifford 1995; guyot et al., 1996;) differ significantly in wet and dry processed green coffees even if entirely identical starting material was used. green coffee seeds contain up to 14 % of chlorogenic acids (cga) which have a marked influence in determining coffee quality and play an important role in the formation of coffee acidity and bitterness (selmar et al. 2000). the main groups of cga found in green coffee beans are caffeoylquinic acids; 3caffeoylquinic acid (cqa) (10% of total cga), 4cqa(10% of total cga), 5-cqa (56-62 % of total cga); 3,4-dicaffeoylquinic acids (dicqa); 3,5dicaffeoylquinic acids; 4,5 dicaffeoylquinic acids) all about 15-20% of total cga; feruloylquinic acids (5-13% of total cga); caffeoylferuloylquinic acids (the remaining percentage) (clifford, 2003). the relatively high levels of chlorogenic acids and related compounds in coffee seeds reflect their physiological importance for the coffee plant, as well as their significant contribution to aroma and flavour formation of coffee beverage. genetic factors, the degree of maturation, and to some extent environmental conditions and agricultural practices, are important determinants of the composition of chlorogenic acids in green coffee beans, and will also affect the final beverage. high levels of chlorogenic acid (cga) were found to associate with low quality coffees and vice-versa (selmar et al., 2000). a study revealed a disagreeable flavour to coffee beverage due to addition of dicqa, which disappeared on subsequent addition of cqa (selmar et al., 2000). moreover, silva (1999) found higher cga content in lower quality samples. farah et al. (2006) also observed a strong association between higher levels of cqa (accounts for 60% of cga contents in roasted coffee) and fqa and low cup quality. coffee cup quality is reported to relate directly to polyphenol oxidase activity, and 5-cqa levels in mature coffee fruits seem to be inversely associated with polyphenol oxidase activity in coffee beans (silva, 1999). arabica coffees from certain regions of ethiopia (e.g. sidamo, yirgacheffe, and harar) fetch premium prices (stanculescu et al., 2011). there are other hitherto unknown regions in the country where ‘fine specialty https://driftaway.coffee/author/scottdriftaway-co/ https://driftaway.coffee/author/scottdriftaway-co/ https://driftaway.coffee/author/scottdriftaway-co/ https://driftaway.coffee/author/scottdriftaway-co/ adugnaw and nigussie green coffee beans quality and biochemical composition 89 coffees’ are produced that are highly rated on the market (adugnaw et al., 2015b). it is generally understandable that inherent coffee quality could be influenced by environmental and management factors (gichimu et al., 2014). the role of chemical soil properties has been studied (adugnaw et al., 2015a). the diversity of suitable varieties, soil type, climate, cultivation methods, among others, enables ethiopia to produce diverse and unique quality coffees for local and world markets (tadesse, 2015). to cope with the growing consumption and demand of high quality coffee, improvement and valorisation of coffee quality in the coffee chain provides a new impetus, resulting in the segmentation of the market with substantial premium prices in the world (hilina, 2010; adugnaw et al., 2015b). this scenario has led coffee-producing countries to give much attention to genetic, environmental, and management factors to cope with the market demands (hilina, 2010). however, no sufficient information is available on the effect of altitude, shade and processing methods as well as associations of coffee quality attributes with biochemical composition of green coffee beans in ethiopia. thus, the objective of this study was to elicit information on the effect of altitude, shade, and processing methods on coffee quality attributes and their associations with the biochemical composition of green coffee beans. 2. materials and methods 2.1. site selection the study was conducted on coffee beans collected from three farms in south-western ethiopia located at altitudes of 1150, 1545 and 1802 meters above sea level, which are designated as lowland, midland, and highland coffee growing areas in the country, respectively, (moa, 2003). the coffee beans were collected from both shaded and unshaded coffee trees in all three farms. according to the national meteorological services agency (2010), the study region is characterized by a mono-modal rainfall pattern of about 1565 mm, maximum and minimum temperatures of 26.1 and 13.20c, respectively, relative humidity of 73.3%, and sunshine hours of 5.4 (table 1). the farms were purposely selected considering the altitudinal ranges and uniformity in management methods. the selected farms belonged to the coffee plantation development enterprise. nine sub-coffee farms were selected with shaded plots and unshaded plots. 2.2. experimental procedures 2.2.1. coffee berry collection ripened coffee cherries were hand-picked at their peak ripening stages during the 2010/11 cropping season out of which washed and unwashed green coffee beans were carefully prepared without contamination in three replicates. table 1. location of study sites. farm region latitude longitude altitude (meters above sea level) bebeka (n= 3) benchmaji/ snnprs1 6056.580’n 35030.607’e 1150 goma (n= 3) jimma/ oromia 7055.253’ 36037.069’ 1545 kossa (n= 3) jimma/ oromia 7057.223’n 36052.664’e 1802 note: 1snnprs = southern nations, nationalities, and peoples regional state 2.2.2. laboratory analysis cupping analysis: a total of 36 coded samples (18 washed and 18 unwashed green coffee beans) with a moisture content of about 10.5% were used for the experiment. the coffee samples were handed over to ecx (100 g each), jimma centre. raw quality analysis (40%): the weight of 100 green coffee beans (hbw) for each sample was measured using a sensitive balance. then the entire green coffee bean sample weighing 100 g for each sample was used for raw evaluation test before roasting. then, primary and secondary defects, shape-make, colour, and odour of the coffee samples were assessed according to the procedure used by the ethiopian commodity exchange (ecx) (ecx, 2010). according to ecx (2010) one full defect of primary defect is equated with one full black, one full sour, one pod/cherry, two large stones, five medium stones, two large sticks, or five medium sticks. moreover, one full defect of secondary defect is equated with any of the following: parchment (2-3), hull/husk (2-3), broken/chipped (5), insect damage (2-5), partial black (2-3), partial sour (2-3), floater (5), shell (5), small stones (1), small sticks (1), or water damage (2-5). roasting and brew preparation: a batch roaster equipped with a cooling system, in which air was forced through a perforated plate, capable of roasting up to 500 g green coffee beans, was used for roasting the coffee beans. the entire 100 g of each bean sample was used and the beans were carefully roasted at the temperature of 170 200 0c to a medium brown roast colour (7 – 8 minutes). the roasted beans were ground to a medium level using guatemala sb coffee grinder. then, the powder was brewed. the water used for brewing contained 0.3 mmol to 1.2 mmol of calcium carbonate (caco3), which was free from chlorine or other foreign flavour-affecting factors. using the preheating graduating cylinder, 150 ml of boiled water (93 0c) was poured into a cup containing 12 g of roasted coffee powder and the infusion was allowed to steep for approximately 4 minutes to settle. the cup was then evaluated for its aroma. then, the surface of the beverage was skimmed off to remove foams after which it was cooled down to a comfortable temperature (55 0c) for tasting (iso, 2004). cup quality analysis (60%): a panel of three trained, experienced, and internationally certified (q graders) cuppers took 6 to 8 cc of the brew from 5 cups using adugnaw and nigussie east african journal of sciences volume 12 (2) 87-100 90 soup spoons and forcefully slurped it to spread evenly over the entire surface of the tongue and palate and then expectorated onto a spittoon. cup cleanness, acidity, body, and flavour were evaluated as per the standard method (ecx, 2010). finally, the preliminary grade assessment was made based on the sum of scores of the raw and cup quality analyses which gives the total point. according to the definition by ecx (2010) raw value is the sum of points of primary defect, secondary defect, shape-make, colour, and odour, while cup quality is the sum of points of cup defect (number of cup defects out of five cups tested), acidity, body, and flavour (coffee brew taste in the mouth which indicates the natural and specific coffee characteristics). chemical analysis: green coffee beans were subjected to freeze drying just before grinding to fine powder using a hand-held electrical blade coffee grinder (bosch mkm 6003 uc, bean container capacity: 75 g, power: 180 watt). grinding was assumed to be sufficient when the powder escaped to the ceiling of the cap of the grinder, and the powder was immediately packed in a plastic cup with a tight stopper, and kept in a desiccator until the laboratory analyses were conducted. caffeine, trigonelline and chlorogenic acids: the caffeine, trigonelline and chlorogenic acid contents were determined using hplc/thermo following the method of alonso-salces et al. (2009): 0.1 g freeze dried green coffee powder was weighed in an erlenmeyer flask of 50 ml. 10 ml of meoh/acetic acid (30:7.5:2.5) containing 2 mg/ml ascorbic acid was added and then placed in an ultrasonic bath for 15 minutes. the extract was filtered using whatman filter papers no.2, and subsequently over a 0.45 micrometer ptfe filter after which 1 ml of the filtrate was taken in a vial and injected into the hplc/thermo. the standard solutions of chlorogenic acid, caffeine and caffeic acid were mixed each at 0.5/1/1.5 mg/ml in one mixture in methanol and each solution was injected twice for calibration. a calibration curve was made using the standard concentration and area of sample and subsequently used to calculate the composition of the respective biochemical components using the area generated after the retention time. the detection was carried out at 278 nm (caffeine and trigonelline), and 324 nm (cga). for the identification and quantitative analysis, a standard curve was prepared using standards of caffeine, trigonelline, and chlorogenic acids. sucrose measurement: sucrose of the coffee beans was determined using gc varian 3800 following the standard method. a sample of green coffee powder was freeze-dried and weighed (0.5 1 g) in 50 ml volumetric flask to which 30 ml distilled water plus 5 ml frozen internal standard solution (iss) (phenyl-b-dpyranoside) were added. the sample was placed at 60 0c for 30 minutes after which it was cooled. next, 0.5 ml each of carre i (15 g znso4 and 7.5 g carre ii (k4fclcn)6 were added to de-protein the sample. the distilled water was then filled to the label of the mark on the 250 volumetric flasks and shaken well to homogenize the mixture. the solution was immediately filtered with whatman filter papers, and subsequently 1 ml filtrate was taken in small bottles using a glass pasteur pipette and dried under nitrogen drier using hollow needles to let nitrogen into the bottle. to this dry extract was added 1 ml stox (2.5 g hydroxylamine hydrochloride diluted with dry pyridine to 100 ml) under hood and kept at 60 0c for 30 minutes after which it was cooled. then, 1 ml of hmds (hexamethyldisilazan) was added and subsequently 0.1 ml tfa (trifluor acetic acid) was added before sedimentation for 60 minutes to get a clear extract solution. from the clear extract solution, 1 ml sample was taken in a vial with rubber stopper to inject to gc varian 3800. 2.3. statistical analysis frequency distribution of the preliminary grade was determined as a function of altitude, shade and processing methods. covariance analysis, univariate analysis of variance and tukey hsd method of mean separation were applied to separate significant mean differences. moreover, pearson correlation and stepwise multiple regression analyses were conducted to examine the relationship between coffee quality attributes and various potential predictors using spss 16 v2 software (ibm, 2007). 3. results 3.1. preliminary coffee quality attributes the preliminary coffee quality attributes are depicted in table 2 and figure 1a-g. the effect of processing methods was significant (p ≤ 0.05) on primary defect, secondary defect, odour, total-point, and preliminary grade. with regard to primary defect, secondary defect, odour, total-point and preliminary grade, unwashed coffee had higher values than washed coffee. although non-significant, washed coffee showed better score for acidity, body, and flavour attributes. other results indicated no significant differences owing to altitude and shading on the attributes mentioned above. although non-significant, subtle differences existed that may determine prices in the market. in line with this suggestion, with the exception of colour and secondary defect, and odour which were better at lowland and midland, respectively, the remaining attributes showed better score at highlands (fig.1). as clearly depicted in figure 1a-g, highland coffees dominantly scored higher values for preliminary coffee quality attributes. colour and shape-make attributes were favoured under shaded condition whilst the remaining attributes, including secondary defect, primary defect, acidity, body, flavour, total-point, preliminary grade and specialty-total were favoured by unshaded condition. the combined analysis of altitude, shade and processing methods on preliminary coffee quality attributes revealed that none of the interactions was significant (p > 0.05). in fact, the subtle differences indicated that the highest total-point and preliminary grade were recorded for the highlands with shade and the least for the lowlands with shade. with regard to total-points and preliminary grade, washing favoured production of better coffee beans at the lowlands and http://www.analytics-shop.com/gb/sample-preparation/filtration/whatman-filter/whatman-filterpapers.html http://www.analytics-shop.com/gb/sample-preparation/filtration/whatman-filter/whatman-filterpapers.html adugnaw and nigussie green coffee beans quality and biochemical composition 91 midlands than not washing. however, the best unwashed coffees were obtained from the highlands. both shaded and unshaded coffees had the highest quality score of preliminary grade under the unwashed method of preparation than under the washed method of preparation. table 2. preliminary coffee quality attributes as affected by processing methods. sample lot primary defect secondary defect odour@ acidityɛ body flavour total point preliminary grade† specialty+ washed 8.3±0.3b 4.9±0.8b 5.0±0.1b 11.5±0.3a 10.2±0.4a 10.5±0.4a 75.8±1.6b 2.9±0.2b 81.5±0.9a unwashed 14.8±0.3a 11.6±0.9a 9.8±0.1a 10.8±0.3a 9.9±0.4a 10.3±0.4a 82.4±1.6a 2.3±0.2a 80.0±0.9a p-value <0.001 <0.001 <0.001 0.131 0.631 0.792 0.007 0.034 0.235 sd 3.5 4.7 2.5 1.4 1.4 1.8 7.5 0.8 3.8 cv% 30.8 57.6 33.6 12.5 14.5 17.5 9.4 29.3 4.7 note: means followed by the same letter within a column are not significantly different at 5% level of significance. preliminary grade is the ranking of the sum of raw and cup analysis points during preliminary assessment which helps to differentiate coffee that has potential for being sold as specialty coffee with other commercial coffees; +specialty coffee is distinctive because of its full cup taste and little to no defects and commands premium prices in the international coffee market; body is the sensory perception of the mouth-feel of the brew. it is a combination of the fats, oils, and sediment swept off the surface of the freshly ground coffee particles and suspended in the unfiltered brew; ɛacidity is the corporeal gustatory perception of the hydrogen ions present in the brew, an actual physical sensation on the tongue. @odour is olfactory perception, olfactory sensation, smell, which is the sensation that results when olfactory receptors in the nose are stimulated by particular chemicals in gaseous form; flavour is the perceived combination of aroma and taste, with the modulation of the basic tastes: sweet, sour, bitter, salty, achieving a distinctive cup characteristic. the aroma is experienced retro-nasally through the back of the palate as the coffee is aerated in the mouth while it is slurped (scaa, 2004; ecx, 2010). the frequency of obtaining preliminary grade 1, 2, 3, 4, 5 and q1, q2, and commercial grade (3) was 2.8%, 41.7%, 44.4%, 5.6%, 2.8%, 8.3%, 41.7%, and 41.7%, respectively (table 3). the high altitude contributed high number of first grade and q1 grade point. unshaded and unwashed coffee grade was better most likely owing to favourable climatic conditions prevailing in south-western ethiopia. unwashed coffee had superior quality attributes most likely due to better physiological development and uniform maturity of the fruit under optimal weather conditions note: the altitudes lowland =1000 – 1550 midland = 1551 – 1750 highland = 1751 – 2150 source: moa, 2003 figure 1. frequency of preliminary coffee quality attributes as a function of altitude https://www.vocabulary.com/dictionary/olfactory%20perception https://www.vocabulary.com/dictionary/olfactory%20sensation https://www.vocabulary.com/dictionary/smell adugnaw and nigussie east african journal of sciences volume 12 (2) 87-100 92 table 3. frequency of preliminary and specialty grade by altitude, shade and processing methods in south-western ethiopia. factor preliminary grade® specialty grade© 1 2 3 4 5 q1 q2 commercial (c3) missing system 1150 m altitude (n=12) 5 6 1 3 8 1 1545 m altitude(n=12) 4 6 2 6 4 2 1802 m altitude (n=12) 2 6 4 3 6 3 shaded (n=6) 1 6 9 1 1 5 1 unshaded(n=6) 1 9 7 1 3 3 washed (n=6) 6 9 2 1 2 3 1 unwashed (n=6) 2 9 7 1 5 total (%) 97.2 (2.8 missing) 2.8 41.7 44.4 5.6 2.8 8.3 41.7 41.7 8.3 note: ® preliminary grade: according to ecx (2010) grade 1 is the coffee that has a total value (raw value + cup quality value) of more than 85; grade 2 between 75 -84; grade 3 between 63 74; grade 4 between 47 -62; and grade 5 between 3 – 45 percent. ©specialty grade green coffee (q1): according to scaa (2004) specialty green coffee beans have no more than 5 full defects in 300 grams of coffee. no primary defects are allowed. a maximum of 5% above or below screen size indicated is tolerated. specialty coffee must possess at least one distinctive attribute in the body, flavour, aroma, or acidity. it must be free of faults and taints. no quakers (unripened coffee beans, often with a wrinkled surface. quakers do not darken well when roasted) are permitted. moisture content is between 9-13%; premium coffee grade (q2): premium coffee must have no more than 8 full defects in 300 grams. primary defects are permitted. a maximum of 5% above or below screen size indicated is tolerated. it must possess at least one distinctive attribute in the body, flavour, aroma, or acidity. it must be free of faults and may contain only 3 quakers. moisture content is between 9-13%; commercial coffee grade (c3): commercial (exchange grade) coffee must have no more than 9-23 full defects in 300 grams. it must be 50% by weight above screen size 15 with no more than 5% of screen size below 14. no cup faults are permitted and a maximum of 5 quakers are allowed. moisture content is between 9-13 % (scaa, 2004; ecx, 2010). the variance estimates of the total-point attribute indicated that on average, 7.1%, 2.3%, and 29.4% of the total variations were contributed by altitude, shade, and processing methods, respectively (table 4). table 4 .variance estimates of dependent variables: total-point attributes. component estimate percent contributed for by var (altitude) 4.825 7.1 var (shade) 1.554 2.3 var (processing methods) 19.919 29.4 var (error) 41.464 61.2 total 67.762 100.0 method: anova (type iii sum of squares) 3.2. biochemical composition of green coffee beans the results of the biochemical compositions of green coffee beans are presented in table 5. caffeine: the caffeine content of the coffee beans was unaffected by altitude, processing method, and shade. 3-caffeoylquinic (3-cqa): the content of 3-cqa of the coffee beans was not affected by altitude and shade. however, it was significantly (p < 0.05) affected by coffee processing method. the content of this chemical composition in cofffee beans was found to be significantly higher for unwashed cofffe beans than washed coffee beans by about 11%. 4-caffeoylquinic acid (4-cqa) and 5caffeoylquinic acid (5-cqa): the contents of 4cqa and 5-cqa of the coffee beans were affacted by altitude, with significantly higher contents obtained for the high and middle altitudes than the low altitude. however, the contents of the two biochemical compositions were not affected by shade. on the other hand, coffee processing methods influenced the content of 5-cqa wheras it did not affect that of 4cqa. thus, the 5-cqa content of washed coffee was higher than that of unwashed coffee by about 3%. feruloylquinic acids (fqa): altitude significantly (p < 0.05) influenced the coffee bean content of fqa, with significantly higher levels recorded for coffee beans originating from the low and middle altitudes than the high altitude. this means increasing the altitude at which coffee is grown reduces the fqa content of the bean. however, coffee processing method and shade did not affect this parameter. 3, 4-dicaffeoylquinic acids (3,4-dcqa) and 4,5dicaffeoylquinic acid (4,5-dcqa): altitude significantly (p ≤ 0.05) influenced the contents of both 3, 4-dcqa and 4, 5-dcqa in the bean. but, shade did not affect the composition of both chemicals in the bean. coffee beans originating from the low altitude areas contained significantly higher amounts of 3, 4adugnaw and nigussie green coffee beans quality and biochemical composition 93 dcqa than coffee beans that originated from the mid altitude and high altitude areas. almost similarly, coffee beans that originated from low and mid altitude areas contained significantly higher amounts of 4, 5-dcqa than coffee beans that originated from the high altitude areas. the coffee bean content of 4, 5-dcqa was significantly influenced also by coffee processing method. thus, washed coffee beans contained significantly higher amounts of 4, 5-dcqa than unwashed coffee beans. the 4, 5-dcqa content of washed coffee beans exceeded that of unwashed coffee beans by about 37%. caffeoylferuloylquinic acids (cfqa): the cfqa content of coffee beans was significantly (p< 0.05) affected by altitude, shade, and processing method. thus, coffee beans that originated from the low and middle altitudes had significantly higher contents of cfqa than coffee beans that originated from the highlands. unshaded coffee had significantly higher content of cfqa than shaded coffee. the content of cfqa in the bean obtained from coffee beans that originated from unshaded coffee trees was about 16% higher than the cfqa content of coffee beans that originated from shaded coffee trees. unwahed coffee had significantly higher content of cfqa than shaded coffee. the amount of cfqa content obtained from unwashed coffee beans was about 46% significantly higher than that obtained from washed coffee beans. total chlorogenic acid (tcga): the tcga content of coffee beans was significantly (p < 0.05) influenced by altitude and processing method, but not by shade. the tcga content of coffee beans originating from the low and middle altitude significantly exceeded the content of tcga obtained from coffee beans originating from the high altitude by about 8%. similarly, the tcga content of washed coffee beans significantly exceeded that of unwashed coffee beans by about 3%. sucrose: the sucrose content of green coffee beans was significantly influenced by altitude. however, the content of this biochemical composition in the coffee bean was unaffected by both shade and processing method. the results clearly indicated that, increasing the altitude where coffee is grown consistently decreased sucrose content of the beans. thus, the sucrose content of coffee beans originating from the low altitude areas was significantly higher than the sucrose contents of coffee beans that originated from middle altitude and high altitude areas by about 17% and 27%, respectively. trigonelline: the trigonelline content of coffee beans was significantly (p ≤ 0.05) influenced by altitude and processing method. similarly, this chemical composition of the bean was significantly influenced by processing method. however, shade did not influence the content of this chemical composition in the coffee bean. increasing the altitude at which coffee is grown significantly decreased the trigonelline content of the bean. thus, the trigonelline content of coffee beans originating from the low altitude areas significantly exceeded the trigonelline content of coffee beans obtained from coffee beans originating from the middle altitude and high altitude by about 2% and 7%. similarly, the trigonelline content of washed coffee beans significantly exceeded that of unwashed coffee beans by about 2%. adugnaw and nigussie east african journal of sciences volume 12 (2) 87-100 94 table 5. effect of altitude, shade and processing methods on biochemical composition of green coffee beans in south-western ethiopia. variables of study caffeine 3-cqa 4-cqa 5-cqa fqa 3,4dcqa 4,5dcqa cfqa tcga sucrose trigonelline altitude (m) 1150 (12) 13.6±0.2 3.9±0.2 5.7±0.1b 27.2±0.3b 4.5±0.2a 4.1±0.2a 8.1±0.3a 4.0±0.1a 57.4±0.6a 58.8±2.2a 87.6±0.3a 1545 (12) 14.4±0.2 4.0±0.2 6.4±0.1a 28.9±0.3a 4.8±0.2a 2.9±0.2b 7.1±0.3a 3.2±0.1b 57.2±0.6a 50.1±2.2b 86.0±0.3b 1802 (12) 13.9±0.2 3.8±0.2 6.0±0.1a 28.2±0.3a 4.2±0.2b 2.3±0.2b 5.8±0.3b 3.1±0.1b 53.2±0.6b 46.2±2.2b 81.6±0.3c p-value 0.08 0.585 0.013 0.002 0.014 <0.001 <0.001 <0.001 <0.001 0.001 <0.001 shade shaded 14.2±0.2 3.8±0.1 5.9±0.1 27.9±0.2 4.6±0.1 2.9±0.2 7.2±0.2 3.2±0.1b 55.4±0.5 52.9±1.8 84.8±0.3 unshaded 13.7±0.2 4.1±0.1 6.1±0.1 28.2±0.2 4.4±0.1 3.2±0.2 6.8±0.2 3.7±0.1a 56.5±0.5 50.5±1.8 85.3±0.3 p-value 0.111 0.123 0.201 0.531 0.259 0.215 0.354 0.002 0.12 0.344 0.274 processing washed 14.2±0.2 3.7±0.1b 6.0±0.1 28.5±0.2a 4.6±0.1 3.1±0.2 8.1±0.2a 2.8±0.1b 56.7±0.5a 49.2±1.8 85.9±0.3a unwashed 13.7±0.2 4.1±0.1a 6.0±0.1 27.6±0.2b 4.3±0.1 3.1±0.2 5.9±0.2b 4.1±0.1a 55.2±0.5b 54.2±1.8 84.2±0.3b p-value 0.111 0.029 0.867 0.025 0.085 0.945 <0.001 <0.001 0.029 0.064 <0.001 sd 0.9 0.6 0.5 1.5 0.6 1.0 1.7 1.0 3.1 11.0 3.9 cv% 6.5 14.3 8.7 5.4 13.7 32.4 24.4 28.1 5.5 21.3 4.6 note: means followed by the same letter are not significantly different at 5% level of significance; 3-cqa = 3-caffeoylquinic acid; 4-cqa = 4-caffeoylquinic acid; 5-cqa = 5-caffeoylquinic acid; fqa = feruloylquinic acids; 3,4-dcqa = 3,4-dicaffeoylquinic acids; 4,5-dcqa = 4,5-dicaffeoylquinic acid; cfqa = caffeoylferuloylquinic acids; tcga = total chlorogenic acid. adugnaw and nigussie green coffee beans quality and biochemical composition 95 3.3. stepwise multiple regression stepwise multiple regressions were conducted to evaluate whether the biochemical compositions of the green coffee beans could predict preliminary coffee quality attributes. the regression analysis between biochemical compounds and preliminary coffee quality attributes (tables 6 &7) showed significant contributions of the model to all attributes tested indicating significant positive regression weights. with regard to flavour, acidity, and shape-make, the predictors entered to first model included 4,5-dcqa, sucrose, and fqa, respectively (table 6). the model contributed to about 16%, 14% and 11% of the total variations of flavour, acidity, and shape-make attributes, respectively. in this regard, the outcomes were negatively related to the respective predictors with the magnitude of 7.25%, 0.47%, and 5.85% of the variation in flavour, acidity, and shape-make accounted for by 4,5-dcqa, sucrose, and fqa, respectively (table 6). with regard to odour attribute, three models (model 1, model 2 and model 3) contributed to about 44%, 67%, and 71% of the total variations, respectively. among the predictors entered into the respective models, cfqa gave the best and positive prediction while 3,4-dcqa and 4,5-dcqa showed negative and respectively second and third most important prediction to the attribute. cfqa significantly affected odour attribute by 19.02% while 3,4-dcqa and 4,5-dcqa affected the attribute by 4.74% and 7.5% (p ≤ 0.001). regarding primary defect attributes, the model 1 & 2 showed significant contribution at the magnitude of 5.14% and 7.38%, respectively. in this regard, cfqa was found to be the best positive predictor followed by negative relation of 3, 4-dcqa with the magnitude of 21.19% and 10.63% of the variation of the outcome. moreover, model 1(p ≤ 0.002) &2 (p ≤ 0.001) had significant contributions to secondary defect attribute contributing 2.47% and 4.47% variation in the outcome. positive effect of cfqa and negative effect of trigonelline showed about 31% and 6% of the variation of secondary defect attribute. the totalpoint attribute which determines the final grade for marketing was most negatively affected by fqa (p ≤ 0.013) followed by 3, 4-dcqa (p ≤ 0.017) predictors (table 7). first and second models significantly (p=0.001 and p ≤ 0.001) contributed for the variation of the outcome with the magnitude of about 2.6% and 3.8%, respectively. thus, the final coffee grade could be most affected by increased level of the predictors in descending order of fqa and 3,4dcqa composition of green coffee beans. this study did not reveal any association between the coffee quality attributes considered and biochemical compounds including caffeine, 3-cqa, 4-cqa, 5cqa, and tcga composition of green coffee beans. table 6. the model for stepwise regression of preliminary cup quality attributes on biochemical composition of green coffee beans in south-western ethiopia. dependant variable model r r2 adjusted r2 se. of the estimate model p-value (regression) flavour 1 .397 .158 .133 1.701 0.016 acidity 1 .379 .143 .118 1.273 0.023 odour 1 .665 .442 .426 1.837 <0.001 2 .812 .659 .639 1.457 <0.001 3 .841 .708 .680 1.370 <0.001 shape-make 1 .332 .110 .084 1.037 0.048 primary defect 1 .717 .514 .500 2.506 <0.001 2 .859 .738 .722 1.868 <0.001 secondary defect 1 .497 .247 .225 4.045 0.002 2 .692 .479 .447 3.416 <0.001 total-point 1 .510 .260 .238 6.522 0.001 2 .615 .378 .340 6.069 <0.001 adugnaw and nigussie east african journal of sciences volume 12 (2) 87-100 96 table 7. regression of preliminary coffee qualities attributes on biochemical composition of green coffee beans in south-western ethiopia. dependant variable variable in the model unstandardized coefficients b std. error standardized coefficients beta t sig. flavour 4,5-dcqa -.725 .287 -.397 -2.524 0.016 acidity sucrose -.047 .020 -.379 -2.385 0.023 odour cfqa 1.902 .329 .755 5.780 ≤0.001 3,4-dcqa -.474 .165 -.334 -2.871 0.007 4,5-dcqa -.749 .326 -.309 -2.301 0.028 shape-make fqa -.585 .285 -.332 -2.053 0.048 primary defect cfqa 2.119 .344 .580 6.162 ≤0.001 3,4-dcqa -1.063 .203 -.493 -5.231 ≤0.001 secondary defect cfqa 3.066 .627 .642 4.892 ≤0.001 trigonelline -.590 .154 -.503 -3.832 0.001 total-point fqa -4.650 1.779 -.383 -2.614 .013 3,4-dcqa -1.602 .640 -.366 -2.503 .017 4. discussion the results indicated non-significant effect of altitude and shading on the studied coffee quality attributes. consistent with the results of this study, findings by avelino et al. (2005) in costa rica, salvador at 1200 and 1300 meters above sea level also showed similar results where non-significant differences were observed between the varieties in either overall preference or body. effect of altitude: the general trend of attributes indicated that most highland samples scored better values than lowland and midland samples (figure 1). as a result, high altitude contributed high number of first grade and q1 grade point. avelino et al (2005) also found a positive relation between altitude and taster preferences in orosi and santa mar´ıa de dota. similar studies by bertrand et al. (2006) found that samples originating from higher elevations (1350, 1400 and 1450 m) had higher beverage preference scores than samples from lower elevations (900, 1100, 1200 and 1300 m). the highest score values for highland coffees may be due to regulated temperature. the findings of bertrand, et al. (2006), guyot et al. (1996) and rojas, (1985) are in agreement with this result in which elevation was explained by temperature. it is generally accepted that, in the tropical climate, an increase in elevation of 100 m decreases the mean daily temperature by 0.65–10c (guyot et al., 1996). it is understood that temperature plays an important role in the phenologic cycle of coffee, particularly on berry development and physiological maturity. coffee berries grown at high altitude experience lower temperatures which lengthen the maturation period leading to higher accumulation of aroma precursors (avelino et al, 2005). furthermore, at low altitudes where the climate is warmer than optimal for coffee, shade was found to improve physical quality and organoleptic attributes most likely owing to a reduction in heat-induced stress in the plant and a lengthening of the maturation period of coffee berries (vaast and bertrand, 2006). this study showed that the mean value for 3,4-dcqa, 4,5-dcqa, cfqa, tcga, sucrose, and trigonelline decreased in the order of lowland, midland and highland samples probably due to better physiological maturity at lower temperature which gives the beans longer time to complete physiological maturity (avelino et al., 2005). trigonelline is an important precursor of the volatile compounds that contribute to the aroma and taste of roasted coffee (malta and chagas, 2009). however, for caffeine, 4-cqa, and 5-cqa, the values increased in the order of middle altitude, high altitude, and low altitude coffees whereas for 3-cqa and fqa the increase was in the order of middle altitude, low latitude, and high altitude samples. factors such as variety, soil, microclimate management practices may result in slight variations (vaast and bertrand, 2006). it is well documented that leaf to fruit ratios are higher at high elevations than at low elevations because leaf life span is longer and result in an increased carbohydrate supply to berries and higher bean fat synthesis. furthermore, berry flesh ripening is delayed at the lower temperatures encountered at higher elevations, allowing longer and better bean filling (vaast and bertrand, 2006). in another study by bertrand et al. (2006) elevation was not found to be a determining factor in explaining variation in caffeine and trigonelline concentrations of beans. however, an increase in chlorogenic acid concentration with increasing elevations was reported by decazy et al. (2003) who also reported a trend of more chlorogenic acid accumulation at lower elevations and sharp increments in fat concentration with increasing elevation. this study did not reveal any association between coffee quality attributes considered and biochemical compounds including caffeine, 3-cqa, 4-cqa, 5cqa, and tcga composition of green coffee beans. studies by bertrand et al. (2006) also discovered the same trend where caffeine, trigonelline, fat, sucrose and chlorogenic acid contents did not show good correlations with the sensory characteristics. most highland samples scored better and contributed high number of first grade and q1 grades. as the final adugnaw and nigussie green coffee beans quality and biochemical composition 97 coffee grade was most affected by increased level of fqa and 3,4-dcqa biochemical compositions of green coffee beans, which in turn increased with altitude, these compounds could help as an alternate and complementary means to predict coffee quality. thus, the findings imply that coffee cultivation in ethiopia needs to be gradually shifted towards higher altitudes particularly in response to the climate change and accompanying rising temperatures for sustainable production and for meeting the growing demand for quality coffee in the international market to increase farmers’ income and foreign exchange earnings of the country. effect of shade: most attributes were favoured by absence of shade as compared to shading most probably due to less competition from shade trees and prevailing optimal conditions for the coffee trees to grow and develop. several researchers discussed on both negative and positive influences of shade on coffee quality depending on the ecological variables. for instance, damatta (2004) found positive effects in sub-optimal locations whereas soto-pinto et al. (2000) found negative effects when shade density is above 50%. in other studies, bosselmann, et al. (2009) found negative effects of shade on sensory attributes and positive effects of altitude on physical attributes. similarly, vaast et al. (2005) reported that shade reduces yield by 20–30% under optimal conditions although that is compensated by higher quality beans and coffee prices. unshaded and unwashed coffee grade was better most likely due to favourable climatic conditions prevailing in south-western ethiopia and most likely due to better physiological development and uniform maturity of the fruit under such optimal weather conditions. consistent with this finding, bosselmann et al. (2009) revealed that fragrance, acidity, body, sweetness and preference were negatively influenced by shade cover. previous studies (damatta, f.m., 2004) have shown that shade has a positive impact on coffee quality at lower elevations, implying that optimal agronomic shade management for coffee quality needs site-specific considering climatic and other environmental conditions. under optimal growing conditions, the need for shade declines and this could be an opportunity to maintain high density coffee trees to increase yield per hectare (bosselmann et al. 2009). thus, agronomic shade management for coffee quality should be site-specific considering climatic and other environmental conditions. effect of processing methods: two types of processing methods were applied including washed coffee (green coffee prepared by wet processing of the fruit) and unwashed coffee (green coffee prepared by dry processing of the fruit). unwashed coffee had superior values for primary defect, secondary defect, odour, total-point and preliminary grade while washed coffee showed better score for acidity, body, and flavour attributes which have a distinguishing influence on the ultimate taste profile of coffee origins. the results are in agreement with that of of boot (2011) which summarized that washed coffee tended to have clarity of flavour and aroma that is often lacking in natural coffees. accordingly, acidity comes through more clearly, and the cup is generally cleaner that can have an intensely refreshing character. some studies indicated that processing is determinant of quality recording higher scores for wet-processed coffee than for dry-processed coffee (selmar et al., 2006). this was assumed to be due to the fact that wet-processed coffee had a higher percentage of ripe fruit harvested, while dry-processed had a mixed range of ripe fruits. however, taking samples of similar ripeness showed significant differences in the beans between washed and unwashed lots (selmar et al., 2006). clarke and macrae (1985) also noted that dry processed coffee has a better body due to the fact that the bean was in contact with its mucilage through a greater part of the processing phase, but wet processed arabica tends to be aromatic with a fine acidity due to the formation of acids in under water fermentation, but some astringency. in line with this gonzales rios et al. (2006) found the importance of mucilage removal in water to obtain coffees with better aroma quality. the wet processed coffees were found pleasant with fruity aroma characteristics whereas those obtained by mechanical removal of mucilage were characterized by less pleasant aromatic notes. however, unwashed coffee showed higher value for 3-cqa and cfqa, washed had higher values for 5-cqa, 4,5-dcqa, tcga and trigonilline composition of green coffee beans. furthermore, it was reported that the washed and unwashed methods played a role in complex metabolic processes of the beans during processing and drying due to effects on the sugars and flavor precursors present. varying forms of variability in biochemical composition (lipid, chlorogenic acid, sugar and caffeine content) of green arabica beans was found by joet et al. (2010) where they reported a close correlation between the type of post harvest processing and the content of fructose and glucose in the coffee bean. thus, a small amount of either hexos was present in washed coffee while in unwashed coffees they were significantly higher. it has been revealed that low levels of both fructose and glucose were associated with decrease in the wet process while dry processing did not influence much of fructose and glucose levels. these metabolic processes may be related to germination, which starts to occur even when the period between harvest and final drying is short, and drying may cause stress metabolism that can also play a role in the chemical compounds present (bytof et al., 2005). 5. conclusion this study has demonstrated that both coffee quality attributes and contents of the associated chlorogenic acids, which markedly influence coffee quality and play an important role in the formation of coffee acidity and bitterness, generally improved in response to increased altitude under both shaded and unshaded adugnaw and nigussie east african journal of sciences volume 12 (2) 87-100 98 conditions regardless of washing or not washing the beans. this implies that shifting the area of coffee production from lower to higher altitudes contributes to enhanced coffee quality attributes. this would enable better exploitation of the rising demands for quality coffees in the international market for enhancing foreign exchange earnings and income of coffee farmers in the country. further research needs to be done to optimize the altitude at which to grow the plant for attaining the best quality coffee attributes desired by the international market. 6. acknowledgements the authors are grateful to the iuc-ju soil fertility project for funding the research. we are especially thankful for the laboratory facilities of ghent university, belgium through iuc-ju soil fertility project for providing all facilities required to analyse the coffee bean samples. we are also indebted to ethiopian commodity exchange for testing the coffee quality. 7. references adugnaw mintesnot, 2014. association of arabica coffee quality with geographic origins in ethiopia. phd dissertation, haramaya university, ethiopia, 129 pp. adugnaw mintesnot, nigussie dechassa and ali mohammed, 2015a. association of arabica coffee quality attributes with selected soil chemical properties. east african journal of sciences, 9 (2): 7384. adugnaw mintesnot, nigussie dechassa and ali mohammed, 2015b. bean quality attributes of arabica coffee grown in ethiopia and the potential for discovering new specialty coffees. east african journal of sciences, 9 (2): 121-130. aerts, r., gezahegn berecha, gijbels, p., kitessa hundera, glabeke, s. v., vandepitte, k., muys, b. rolda´ n-ruiz, i., and olivier, h. 2012. genetic variation and risks of introgression in the wild coffea arabica gene pool in south-western ethiopian montane rainforests. evolutionary applications, issn 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trigonelline, chlorogenic acids and sucrose diversity in wild coffea arabica l. and c. canephora p. accessions. food chem., 75: 223-230 leloup, v., gancel, c., liardon, r., rytz, a. and pithon, a. 2005. impact of wet and dry process on green coffee composition and sensory characteristics. 20ème colloque scientifique international sur le café, bangalore, india, pp. 93–101 malta m. r. and chagas, s. j. r. 2009. avaliação de compostos não-voláteis em diferentes cultivares de cafeeiro produzidas na região sul de minas gerais. acta scientiarum agronomy, 31: 57-61. mazzafera, p. and robinson, s. p. 2000. characterization of polyphenol oxidase in coffee. phytochemistry, 55: 285-296. pohlan, hermann a. jurgen and janssens, marc j. j., nd. growth and production of coffee. http://w.w.w.eolss.net/eolss-sample chapter. aspx: accessed on 20 september 2016. rojas, o. 1985. estudio agroclimatico de costa rica. serie publicaciones miscelaneas no. 617. iica, san josé, costa rica, 65 p. scott, b. 2015. how does elevation affect the taste of coffee? coffeecademy, tasting. <https://driftaway.coffee/elevation/> accessed on 05/23/2018. selmar, d. kleinwächter, m. and bytof, g. 2000. metabolic responses of coffee beans during processing and their impact on coffee flavor. in: cocoa and coffee fermentations. p 432 – 462. https://www.researchgate.net/publication/2872733 55_coffee [accessed may 23 2018]. silva, e. b. 1999. fontes e doses de potássio na produção e qualidade de café provenientes de plantas cultivadas em condições edafoclimáticas. universidade federal de lavras, lavras, mg, brasil. doctorate thesis. soto -pinto, l., perfecto, y., castilio-hernandez, j. and caballero-nieto, j. 2000. shade effect on coffee production at the northern tzeltal zone of the state of chiapas, mexico. agric. ecosyst. environ, 80: 6169. stanculescu, d., scholer, m. and kotecha, s. 2011. ethiopia coffee quality improvement project: aid for trade global review: case story. the international trade centre. tadesse woldemariam gole. 2015. coffee production systems in ethiopia. environment and coffee forest forum (ecff), addis abeba, ethiopia. vaast, p. and b. bertrand. 2006. date of harvest and altitude influence bean characteristics and beverage quality of coffea arabica in intensive management conditions. hortscience. vaast, p., bertrand, b., perriot, j.p., guyot, b. and génard, m. 2005. fruit thinning and shade influence bean characteristics and beverage quality of c. arabica in optimal conditions. j. sci. food agric., 86: 197–204. yigzaw desalegn, labuschagne, m. t., osthoff, g. and herselman, l. 2007. variation for green bean caffeine, chlorogenic acid, sucrose, and trigonelline contents among ethiopian arabica coffee accessions. short communication. sinet: ethiopia, j. sc., 30(1): 7-82. hilina, a. 2010. specialty coffee: the new thing at ecx, addis fortune, volume 10, number 10. scaa. 2004. coffee cuppers handbook. scaa cupping form. p. 9. boot, w. j. 2011. ethiopian coffee buying manual: practical guidelines for purchasing and importing ethiopian specialty coffee beans. u.s. contractor implementing usaid/ethiopia’s agribusiness and trade expansion program. fintrac inc. www.fintrac.com, info@fintrac.com. http://w.w.w.eolss.net/eolss-sample%20chapter.%20aspx http://w.w.w.eolss.net/eolss-sample%20chapter.%20aspx https://driftaway.coffee/author/scottdriftaway-co/ https://driftaway.coffee/coffeecademy/ https://driftaway.coffee/coffeecademy/tasting/ https://www.researchgate.net/publication/287273355_coffee https://www.researchgate.net/publication/287273355_coffee adugnaw and nigussie east african journal of sciences volume 12 (2) 87-100 100 east african journal of sciences (2019) volume 13 (1) 15-26 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: slmnbkl092@gmail.com attribution-non-commercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) genetic progress for yield and yield components and reaction to bean anthracnose (colletotrichum lindemuthianum) of large-seeded food type common bean (phaseolus vulgaris) varieties in west shoa zone, ethiopia solomon bekele 1, firew mekbib2, gemechu keneni3, and birhanu amsalu4 1 bako agricultural research center, p. o. box 03, bako, ethiopia 2 haramaya university, p.o.box 138, dire dawa, ethiopia 3 holeta agricultural research center, p. o. box 31, holeta, ethiopia 4 melkasa agricultural research center, p.o.box 436, melkasa, ethiopia abstract: fourteen common bean (phaseolus vlgaris l.) varieties that were released in ethiopia from 1997 to 2012 as large-seeded food type common bean varieties were evaluated with the specific objectives to: (1) estimate the genetic progress made in 15 years of common bean breeding in ethiopia; (2) assess changes in associated traits in the genetic improvement of common bean varieties released in ethiopia; and (3) assess the reaction of common bean varieties to bean anthracnose [clletotrichum lindemuthianum (sacc. and magnus) briosi and cavara]. the study was conducted at two locations, bako and gute during 2014/2015 main cropping season in a randomized complete block design (rcbd) with three replications. days to 50% flowering (df), days to 90% maturity (dm), grain filling period (gfp), hundred seed weight (hsw), biomass yield (bmy), grain yield per plot (gy), harvest index (hi), biomass production rate (kg/ha/day), seed growth rate (kg/ha/day), grain yield per day (kg/ha/day) and anthracnose (1-9) scale data were collected on plot basis and plant height, number of pods per plant, number of seeds per pod, number of seeds per plant and grain yield per plant data’s were collected on plant basis. statistical data analyses were performed for biomass yield, grain yield, seed weight, harvest index and bean anthracnose severity. combined analysis of variance showed highly significant differences among the common bean varieties and between test environments for hundred seed weight. the vxl interaction of seed weight did not show significant difference among the varieties. regression analysis of mean performance at both environments on year of varietal release showed positive relationship for seed weight (r = 0.08), biomass yield (r = 0.04) and anthracnose disease severity (r = 0.10) but negative relationship for grain yield (r = -0.38), and harvest index (r = -0.37). the highest overall locations mean average of grain yield was 2679.5 kg ha-1 for ayenew and the lowest was 1050.2 kg ha-1 for glp-2, the grand mean being 1806 kg ha-1. the annual rates of genetic progresses were 12.7 kg ha-1 (0.13% ha-1 year-1), -48 kg ha-1 (-0.39%), 0.68 g 100 seed-1 year-1 (0.34% 100 seed-1 year1), -0.004% and 0.39% for biomass yield, grain yield, seed weight, harvest index and anthracnose disease severity, respectively. generally, the grain yield was reduced in the period of genetic improvement, due to the consistent performance of the reference variety gofta. stepwise regression indicated that grain yield day-1 (82.5%) and days to mature (21.8%) explained more for the variation of grain yield; but, seed size (-40.2%) was more important cause for grain yield reduction than bean anthracnose (-9.3%). it could, thus, be concluded that the yield of large seeded food type common bean varieties were reduced due to anthracnose and its large seeded for the last fifteen years (19972012) of breeding; in future also managing the disease; especially, anthracnose disease will be crucial and ayenew (26.79.5 kg ha-1), gofta 2627.1 kg ha-1) and fedis (2180.6 kg ha-1) are recommended for production in the study areas. keywords: anthracnose disease severity; canning type; colletotrichum lindemuthianum; common bean; genetic progress; large-seeded; phaseolus vulgaris; relative genetic gain; stepwise regression. 1. introduction common bean (phaseolus vulgaris l., 2n = 22), also referred to as dry bean, is an annual leguminous plant that belongs to the genus phaseolus, with pinnately compound trifoliate large leaves. in ethiopia, it is most likely that the portuguese introduced the crop in the 16th century (wortman, 1997). common bean is grown throughout ethiopia and is increasingly an important commodity in the cropping systems of smallholder producers (the average farm size for smallholder farmers is between 0.25 to 0.5 hectares) for food security and income. common bean has also health benefits being rich in protein content (about 23% for dried shelled beans and about 6% for green beans) and serving as a good source of iron and zinc (both of which are key elements for mental development). the area covered by common bean production in ethiopia was 113,249.95 ha and 244,049.94 ha for white and red common bean respectively with total area of 357,299.89 ha and total solomon et al. east african journal of sciences volume 13(1) 15-26 16 production of about 540,238.94 tons/ha and national average yield was 1600 kg/ha (csa, 2016). common bean is mainly grown in eastern, southern, south western and the rift valley areas of ethiopia (csa, 2016). beans need up to four months of warm weather and are not frost tolerant. they do poorly in very wet or humid tropical climates because of susceptibility to bacterial and fungal diseases. they need well-drained soils with a ph between 6.5 and 7.0 and are sensitive to deficiencies or high levels of minerals in the soil (broughton et. al., 2003). there is a wide range of common bean types grown in ethiopia, including white, mottled, red, and black varieties. the most commercial varieties are pure red and pure white colored beans and these are becoming the most commonly grown types with increasing market demand (ferris and kaganzi, 2008). to support both the growth in domestic and export bean markets, the ethiopian institute of agricultural research (eiar) has developed a range of high yielding, multi-disease resistant bean varieties. they are major sources of proteins in the lowlands where they are consumed as nifro, wasa, shirowat, soup and samosa. currently, according to the ministry of agriculture report on crop variety registered book in 2014, around 50 common bean varieties are under production; additionally, five new varieties (ser 119, ser 125, tatu, waju and ramada) that were released in 2014 are now under production (moa, 2014). common bean production is constrained by several biotic and abiotic environmental stresses. biotic (field and post-harvest pests and plant diseases) and a biotic (drought, excessive rain/flooding, poor soil fertility, heat and cold stressors) factors are known to cause significant reductions in grain yields (wortmann et al., 1998). bean anthracnose [colletotrichum lindemuthianum (sacc. & magnus) briosi & cavara] poses a major constraint on the production of dry bean in ethiopia. bean anthracnose develops early in the growing season and produces brown to black lesions along the veins of the lower leaves. rain spreads the spores of c. lindemuthianum to neighboring plants and further up into the canopy onto the stems and pods, resulting in the formation of brown to black sunken lesions on which the spore-bearing acervuli are formed. a study by tesfaye b (1997) stated that yield loss up to 62.8% due to anthracnose was recorded in ethiopia on susceptible cultivars of common bean like mexican-142, awash-1 and awash melka. yield refers to the mass of product at final harvest, for which dry matter content should be specified. yield potential is the yield of a cultivar when grown in environments to which it is adapted, with nutrients and water non-limiting and with pests, diseases, weeds, lodging, and other stresses effectively controlled. this definition of yield potential is based on the notion that there are yield genes and stress-resistance genes and that a yield potential measurement attempts to measure only the effects of the yield genes. in measuring progress in genetic yield potential, complications can arise as a result of the possibility of interactions between cultivar and growing conditions (evans and fischer, 1999). knowing the information on genetic progress achieved by a crop over time from a breeding program is absolutely essential to develop effective and efficient breeding strategies by assessing the efficiency of past improvement works in genetic yield potential and suggest on future selection direction to facilitate further improvement (waddington et al., 1986; donmez et al., 2001; many investigators did the genetic progress of common bean and they clarify its positive response; but, they don’t did by classifying according to its seed size and my study reveals negative to their response regarding genetic progress. the focus of this genetic progress work has been on the large-seeded food type common bean varieties with the specific objectives to estimate the genetic progress made in improving yield potential of common; bean varieties; to assess changes in associated traits in the genetic improvement of common bean varieties released in ethiopia; and to assess the reaction of common bean varieties to bean anthracnose in ethiopia. 2. materials and methods 2.1. description of the study area the field experiments were carried out at two locations, i.e. bako and gute, west shoa zone of oromia regional state, located 250 and 316 km, respectively, to west of addis ababa. the weather (temperatures and relative humidity) and edaphic conditions of the test locations are summarized and tabulated hereunder (table 1). table 1. description of the test locations for geographical position and physic-chemical properties of the soils. parameters locations bako gute geographical position latitude 09o6'n 09o5'30,n longitude 37o09'e 36o42'0'e altitude (m.a.s.l.) 1650 1918 edaphic characters soil type utisols nitosols soil ph 4.8-5.8 4.5-5.5 weather characters minimum t.(oc) 13.5 25 maximumt. (oc) 28.5 30 mean t. (oc) 21.0 27.5 rh (%) 48.4 57.3 arf (mm) 1067.1 1350 t* = temperature; arf = annual rainfall source: meteorological data of bako agricultural research center (2014) 2.2. treatments/experimental materials fourteen large-seeded food type of common bean varieties that released between 1997 and 2012 from different agricultural research centers in different solomon et al. genetic progress of common bean for yield and reaction to bean anthracnose 17 regions of ethiopia were used. seeds of the common bean test varieties were obtained from bako, melkasa, and sirinka agricultural research centers and haramaya university. the detailed descriptions of the common bean varieties used in the experiment are summarized and depicted in a tabular form hereunder (table 2). table 2. descriptions of the large-seeded food type common bean varieties used in the study at bako and gute, west shoa zone in 2014/15 main cropping season. s. no. varieties year of release maturity days yield (kg ha-1) crosses/ seed source 1 gofta 1997 79.2 2627.1 hu 2 ayenew 1997 82.8 2679.5 hu 3 melke 1998 85.0 1928.7 cross 14 marc/eiar 4 ibado 2003 82.0 1464.8 sari 5 red kidney 2007 77.7 1473.2 marc/eiar 6 kufanzik 2008 78.8 2079.8 hu 7 loko 2009 84.0 1630.4 barc 8 glp2 2011 81.2 1050.2 marc/eiar 9 morka 2011 85.8 1633.8 marc/eiar 10 hirna 2012 87.3 1455.4 hu 11 hundane 2012 84.8 1825.9 hu 12 babile 2012 82.3 1707.4 hu 13 tinike 2012 85.5 1549.2 hu 14 fedis 2012 85.7 2180.6 hu note: marc = melkasa agricultural research center, eiar = ethiopian institute of agricultural research, hu = haramaya university, barc = bako agricultural research center, sari = sirinka agricultural research institute. 2.3. experimental design and field management the experiments were conducted at bako and gute during the 2014 main cropping season.a plot of 6.4 m2 consisting of 4 rows of 4 m length with 0.4 m spacing between rows was used. a distance of 0.5 m was maintained between plots and 1 m between blocks. a seed rate of 100 kg ha-1 was used; 160 and 40 seeds were administered to each plot and each row, respectively. the two middle rows were used for data collection. the treatments were arranged in a randomized complete block design (rcbd). fertilizer was applied at the rate of 100 kg ha-1 diammonium phosphate (18 kg n ha-1, 46 kg p2o5 kg ha-1 and 0 k) and all other crop management practices were carried out as recommended. 2.4. data collection 2.4.1. collected data on plot basis days to 50% flowering (df): number of days from planting to the date on which 50% of plants on the two middle rows produced at least their first flowers. grain filling period (gfp): the number of days between days to flowering and days to physiological maturity. days to 90% physiological maturity (dm): the number of days from planting to the stage when 90% of the plants in a plot have reached physiological maturity, i.e., the stage at which pods lost their pigmentation and began to dry. biomass yield (bmy): determined by weighing the total air-dried above ground biomass yield of plants in the two middle rows. hundred seed weight (hsw): weight of 100 seeds were counted from each plot and weighted. grain yield per plot (gy): grain yield in kilogram of plants from the two middle rows and adjusted to 10% moisture level and then it was converted to kg ha-1. harvest index (hi): proportion of dry grain yield to the aboveground biological yield (biomass yield) was calculated as follows: hi= (1) biomass production rate (kg ha-1 day-1) = (2) seed growth rate (kg/ha/day) = (3) solomon et al. east african journal of sciences volume 13(1) 15-26 18 grain yield per day (kg/ha/day) = (4) bean anthracnose severity: bean anthracnose severity (1-9 scales) was pre-transformed into percentage values and then percentage values were arcsine transformed for statistical data analysis (little and hills, 1978). 2.4.2. collected data on plant basis plant height (cm): the plant heights of five randomly taken plants from each of the two middle rows were measured from the ground level to the tip of the plant at physiological maturity and expressed as an average of heights of five plants per plot. number of pods per plant: the number of pods per plant was counted from five randomly taken plants from the middle two rows and expressed as an average for each plot. number of seeds per pod: number of seeds was counted from five random pods from each of five randomly taken plants per plot and expressed as an average of five plants per plot. number of seeds per plant: it was determined by multiplying the number of pods per plant and number of seeds per pod. grain yield per plant (g): the average seed yield in grams obtained from five randomly taken plants in each plot. 3.5. statistical data analysis all the measured variables were subjected to analysis of variance (anova) following gomez and gomez (1984). the general linear model (glm) of sas statistical package version 9.2 software (sas, 2009) was employed for the analysis. the following model was used for computing the analysis of variance. for over location anova = pijk=  + bi+ vj + lk + (vl)jk + e ijk (5) where pijk= phenotypic observation on variety j in block i at location k (i = 1…b, j = 1…v, and k = 1…l) and b, v and l stand for number of blocks, varieties and location, respectively,  = grand mean, bi= the effect of block i with in location k, vj = the effect of variety j, lk = the effect of location k, (vl)jk = the interaction effect between variety and location, and e ijk = error. for individual location anova = yij = μ+ vi + bj + eij (6) where: yij = observed value of variety i in block j, μ= grand mean of the experiment, vi = effect of variety i, bj = effect of block j, ℮ij = error effect of variety i in block j. least significant difference (lsd) was used to separate treatment means when analysis of variance showed significant differences at 5% probability level. least significant difference means for significantly different interaction effects were separated by sas model (p = 0.05). the homogeneity of error mean squares between the two locations was tested by f-test on variance ratio and combined analyses of variance were performed for the traits whose error mean squares were homogenous (when the error mean square of one location less than by three-fold the error mean square of the second location) using proc glm procedure of sas. the annual rate of genetic gain achieved from past breeding efforts in grain yield and the associated agronomic traits was calculated by regressing the mean performance of each variety on the year of release (expressed as the number of years since 1973) for that variety. the relative annual gains achieved over the years of releases in different characters were determined as the ratio of annual genetic gain, which was estimated from regression to the corresponding estimated values of the oldest variety and expressed as percentage. annual rate of gain (b) =covxy (7) varx where x = the year of variety release, y = the mean value of each character for each variety, cov = covariance and var = variance. correlation coefficients among all characters were calculated using means of each character as: cc between x and y (rxy): (8) where: cc = correlation coefficient; rxy = correlation coefficient between x and y, cov(x, y) = covariance between x and y, var (x) = variance of x and var (y) = variance of y. stepwise regression analysis was carried out on the varietal mean using proc stepwise in minitab to determine those traits that contributed much to yield variation among varieties by using grain yield (response) as dependent variable and the other characters (predictors) as independent variable. 3. results and discussion 3.1. analysis of variance the combined analysis of variance of large-seeded food type of common bean varieties showed that variety by solomon et al. genetic progress of common bean for yield and reaction to bean anthracnose 19 location interaction was highly significant (p≤0.01) differences for seed growth rate, yield (gram plant-1), grain filling period and days to 50% flowering and significant (p≤0.05) for grain yield per day, number of seeds per plant, number of seeds per pod and number of pods per plant (table 3). 3.2. performance of the varieties the combined mean performance of hundred seed weight ranged from the lowest 25.63 g for ayenew to the highest 51.65 g for fedis variety, the grand mean being 40.7 g (table 4). this clearly indicated that common bean varieties released as large-seeded food type in ethiopia so far had significant variation for seed weight trait to be exploited in the future breeding programs. 3.3. genetic progresses from breeding 3.3.1 grain yield there was an average reduction by 720.9 kg ha-1 (5.94%) in grain yield for large-seeded food type of common bean varieties for the past 15 years (table 5) or an annual rate of genetic reduction by 48.06 kg ha-1 (0.39% ha-1 year-1), computed using the first released variety, gofta, as a reference (table 5 and figure 1). this is in contrast with the finding of kebere et al. (2006) who reported that the average relative annual gain in grain yield of haricot bean varieties since 1972 was 3.24% year-1, or about 84.24% for the whole period of 26 years and barley (1.34% ha-1 year-1), (fekadu et al., 2011). table 3. mean squares from the combined analysis of variance of 14 large-seeded food type of common bean varieties evaluated over two locations in west shoa during 2014 main cropping season characters source of variations mean cv (%) r2 loca tion (1) replic ation (2) variety (13) vxl (13) error (26) days to flowering (df) ** ns ** ** 0.96 36.3 2.7 0.94 days to maturity (dm) ** ns ** ns 4.59 83 2.6 0.79 plant height (ph) ** ns ** * 102.59 57.3 17.66 0.84 number of pods per plant (nppp) ** ns ** * 4.9 10.7 20.6 0.69 number of seeds per pod (nspp) ** ns ** ns 0.27 4.2 12.6 0.58 number of seeds per plant (nsppt) ** ns ** * 133.92 44.3 26.1 0.63 pod length (pl) ** ns ** ns 0.55 10.6 7.0 0.84 grain filling period (gfp) ns ns ** ** 6.62 47.7 5.4 0.6 yield in gram per plant (ygpt) ** * ** ** 25.24 18.4 27.3 0.69 hundred seed weight (hsw) ** * ** ns 17.54 40.7 10.3 0.85 biomass production rate in kg ha-1 day-1 (bmpr) ** * ** ns 242.3 68.2 22.8 0.78 seed growth rate in kg ha-1 day-1 (sgr) ** ** ** ** 65.8 37.9 21.4 0.84 grain yield per day in kg ha-1 (gyd) ** ** ** * 21.84 22 21.3 0.85 several similar reports indicated high increases in grain yields of some crops in other countries, like northeast china where high annual yield increase of 0.58% ha-1 per year was obtained from breeding soybean (jin, et al., 2010); canada where 0.45% ha-1 per year increase was obtained from breeding soybean (morrison, et al., 2000); and england where 0.39% ha-1 per year increase was realized from barley breeding for over hundred years (riggs, et al., 1981). on the other hand, the finding of the present study is in agreement with the investigation by egli (2008) who stated that very low grain yield, which was explained in the "attainment of yield plateaus", was also obtained from soya bean breeding in western usa. previously, it was reported that cultivar seed size and yield potential of common bean were negatively associated (peter. et. al., 1994). here in the current study, among large-seeded food type common bean varieties, gofta and ayenew were released in the same year, 1997; but, the variety gofta was chosen as a reference variety to compare and contrast with the other tested common bean varieties since it has an advantage over the variety ayenew for its high yielding potential when it was released and has been extensively distributed to the farmers by its hosting institution, haramaya university. non-consistent gradual reduction of yield of this large-seeded food type of common bean varieties across recently released varieties (table 6) implies that common bean breeding in our country needs future attention for better responses through different breeding strategies, like crossing. for example, if we compare the mean grain yield (2627.1 kg ha-1) (table 6) of gofta, which is one of oldest released common bean varieties, and the mean grain yield (1050.2 kg ha-1) of glp-2, the recently released variety, the mean grain yield of the latter was less by 1576.9 kg ha-1 (59.1%) than the grain yield of gofta. on the other hand, the mean grain yield (1455.4) kg ha-1) of hirna variety, the solomon et al. east african journal of sciences volume 13(1) 15-26 20 most recently released variety, was less by 1171.7 kg ha1 (44.6%) than the mean grain yield (2627.1 kg ha-1) of gofta variety (table 6). only the variety ayenew, which was released in the same year 1997, exceeded by 52.4 kg ha-1 (2%) the mean grain yield (2679.5 kg ha-1) of the variety gofta. the possible main reasons for the lower genetic progresses made for these large-seeded food type common bean varieties were the stability and better adaptation of the first released variety, gofta (table 6). therefore, to bring the drastic change for large-seeded common bean varieties through breeding, the ethiopian researchers are advised to apply rigorous breeding strategies like earlier study when gofta and ayenew varieties were first released and to come up with other promising varieties both in yield and disease resistant. table 4. mean performance of the varieties from combined analysis for hundred seed weight of largeseeded food type common bean varieties at bako and gute, west shoa, in 2014/2015 main cropping season. s.no. large-seeded food type common bean varieties 100 seed weight (g) 1 gofta 29.36 2 ayenew 25.63 3 melke 42.76 4 ibado 44.63 5 red kidney 47.78 6 kufanzic 30.26 7 loko 46.05 8 glp-2 45.91 9 morka 43.63 10 hirna 45.03 11 hundane 42.13 12 babile 37.01 13 tinike 38.01 14 fedis 51.65 mean 40.7 lsd (5%) 4.8 table 5. annual relative genetic gain (anrgg) and average relative genetic gain (argg) in % compared to the oldest variety gofta of large-seeded food type common bean variety. trends in genetic progress obtained from breeding common bean for biomass yield, grain yield, seed size, harvest index and anthracnose severity during the past 15 years 3.4 associations of characters the correlation coefficient is the measures of degree of symmetrical association between two traits and it is used for understanding the nature and magnitude of association among yield and yield components. association between any two traits or among various traits is of very importance to make desired selection of combination of traits (ahmad et al., 2003). therefore, the correlated characters for each other of large-seeded food type of common bean varieties are tabulated hereunder (tables 7). characters characters mean square of regression regression coefficient (b) p value coefficient of determination (r2) gain in 15 years kg ha-1 anrgg year1 (%) argg (%) biomass yield (kg ha-1) 75081.9 12.7 0.86 0.004 190.5 0.13 2.04 grain yield (kg ha-1) 1059099 -48 0.02 0.38 -720.9 -0.39 -5.94 seed weight (g) 215.52 0.68 0.05 0.28 10.2 0.34 5.16 harvest index (%) 0.008 -0.004 0.021 0.37 -0.06 -1.11 -16.61 bean anthracnose severity (%) 71.5 0.39 0.26 0.107 -5.85 -0.07 -1.10 solomon et al. genetic progress of common bean for yield and reaction to bean anthracnose 21 table 6. mean performance and their percentage increase in biomass yield (kg ha-1), grain yield (kg ha-1), seed weight (g), harvest index (%),and bean anthracnose severity (%) of large-seeded food type common bean varieties released during the past 15 years compared to the first released variety gofta. v ar ie ti e s y e ar o f re le as e characters grain yield seed weight harvest index biomass yield anthracnose severity mean weight (kg ha-1) increase over gofta variety mean weigh t (g) increase over gofta variety mean index (%) increase over gofta variety (%) mean yield (kg ha-1) increase over gofta variety mean severity (%) reduction from gofta variety (%) kg ha-1) (g 100-1 seeds, %) (kg ha-1) gofta 1997 2627.1 29.36 0.39 5416.7 10.14 ayenew 1997 2679.5 52.4 2 25.63 -3.73 -12.7 0.34 -12.8 6041.7 625 11.5 18.54 -82.8 melke 1998 1928.7 -698.4 -26.6 42.76 13.4 45.6 0.27 -30.8 6302.1 885.4 16.3 13.48 -32.9 ibado 2003 1464.8 -1162.3 -44.3 44.63 15.27 52 0.27 -30.8 5364.6 -52.1 -1 11.85 -16.8 red kidney 2007 1473.2 -1153.9 -44 47.78 18.42 62.7 0.30 -23.1 4166.7 -1250 -23.1 11.85 -16.8 kufanzic 2008 2079.8 -547.3 -20.8 30.26 0.9 3 0.30 -23.1 5052.1 -364.6 -6.8 23.7 -133.7 loko 2009 1630.4 -996.7 -38 46.05 16.69 56.8 0.28 -28.3 5156.3 -260.4 -4.8 10.14 glp-2 2011 1050.2 -1576.9 -59.1 45.91 16.55 56.4 0.29 -25.7 3385.4 -2031.3 -37.5 20.28 -100 morka 2011 1633.8 -993.3 -37.8 43.63 14.27 48.6 0.30 -23.1 5468.8 52.1 1 11.85 -16.8 hirna 2012 1455.4 -1171.7 -44.6 45.03 15.67 53.4 0.23 -41.1 7864.6 2447.9 45.2 36.9 -263 hundane 2012 1825.9 -801.2 30.5 42.13 12.77 43.5 0.28 -28.3 6406.3 989.6 18.3 20.3 -100.2 babile 2012 1707.4 -919.7 -35 37.01 7.65 26 0.30 -23.1 4947.9 -468.8 -8.7 13.57 -33.8 tinike 2012 1549.2 -1077.9 -41.1 38.01 8.65 29.5 0.24 -29.5 6250 833.3 15.4 15.2 -49.9 fedis 2012 2180.6 -446.5 -17 51.65 22.29 75.9 0.27 -30.8 7500 2083.3 38.5 16.9 -66.7 solomon et al. east african journal of sciences volume 13(1) 15-26 22 table 7. correlation coefficients (r-values) of yield and yield related traits of large-seeded food type common bean varieties. characters df dm ph nppp nspp nsppt pl gfp ygpt sw hi bmpr bmy sgr gyd gy ansiv df 0.59 0.17 -0.19 0.05 -0.17 0.07 -0.35** -0.15 -0.10 -0.34** -0.26* -0.19 -0.32** -0.41** -0.36** -0.19 dm 0.01 -0.01 -0.01 -0.03 0.01 0.54** 0.13 0.20 -0.50** 0.08 0.19 -0.32** -0.33** -0.23* 0.08 ph 0.45** 0.01 0.44** 0.12 -0.16 0.17 -0.33** 0.29** 0.34** 0.32** 0.48** 0.45** 0.45** 0.18 nppp 0.15 0.91** 0.24* 0.14 0.75** 0.04 0.28** 0.29** 0.27* 0.42** 0.43** 0.44** 0.04 nspp 0.42** -0.17 -0.07 0.22* -0.24* 0.29** -0.33** -0.33** -0.04 -0.05 0.06 -0.16 nsppt 0.12 0.14 0.78** -0.04 0.34** 0.16 0.15 0.36** 0.37** 0.38** 0.01 pl -0.07 0.29** 0.48** -0.17 0.25** 0.24* 0.07 0.06 0.06 0.07 gfp 0.30** 0.34** -0.22* 0.37** 0.43** -0.02 0.05 0.12 0.29** ygpt 0.39** 0.03 0.22* 0.23* 0.18 0.20 0.23* 0.03 sw -0.49** 0.31** 0.33** -0.17 -0.14 -0.10 0.02 hi -0.11 -0.18 0.66** 0.65** 0.60** -0.25* bmpr 0.99** 0.62** 0.65** 0.68** 0.39** bmy 0.56** 0.59** 0.64** 0.40** sgr 0.99** 0.98** 0.00 gyd 0.99** 0.03 gy 0.04 ansev note: ** and *, highly significant at p < 0.01 and significant at p < 0.05 respectively; and values with no asterisks are insignificant; df = days to 50% flowering, dm = days to maturity, ph = plant height (cm), nppp = number of pods plant-1, nspp = number of seeds pod-1, nsppt = number of seeds plant-1, pl = pod length (cm), gfp = grain filling period, ygpt = yield gram plant-1, sw = seed weight (g), hi = harvest index (%), bmpr = biomass production rate( kg ha-1), bmy = biomass yield (kg ha-1), sgr = seed growth rate (kg ha-1), gyd = grain yield (day-1 kg ha-1), gy = grain yield (kg ha-1+, ansev = anthracnose severity (%) solomon et al. genetic progress of common bean for yield and reaction to bean anthracnose 23 the association of characters of large-seeded food type common bean varieties ranged from -0.50 to 0.99 (table 7). grain yield was negatively associated with days to flowering (r = -0.36**) and days to physiological maturity (r = -0.23), while it was positively correlated with plant height (r = 0.45**), number of pods per plant (r = 0.44**), biomass yield (r = 0.64**), biomass production rate in kilogram per day (r = 0.68**), number of seeds plant-1 (r = 0.38**), seed growth rate in kilogram per day (r = 0.98**), grain yield in kilogram per day per hectare (r = 0.99**), harvest index (r = 0.60**) (table 7). similarly, correlation between grain yield with grain yield per day (white and izquierdo, 1991), with grain yield per day and biomass production rate were highly correlated (waddington et al., 1987; teklu, 1998). some authors also stated that grain yield was related positively with biomass yield; for instance, kebere et al. (2006) on haricot bean; laing et al. (1984) and saladonavaro et al. (1993) on soybean; and teklu (1998) on tef, obtained similar results. but, the findings of these authors indicated that grain yield showed no association with harvest index on their respective studied crops; this contradicts with the present finding. on the other hand, other authors reported that grain yield had positive association with both biomass yield and harvest index (riggs et al., 1981; waddington et al., 1987; perry and d’antuono, 1989) and their findings are in agreement with the current study. in another case study, tarekegne (1994) stated that no relation between grain yield and biomass yield and positive association between grain yield and harvest index were reported on bread wheat. according to kebere et al. (2006), seed growth rate, grain yield per day and biomass production rate were positively associated with grain yield. as kebere et al. (2006) stated, there was no correlation between grain yield and plant height; but the present finding stated that there was strong association between grain yield and plant height and supported with the finding of riggs et al. (1981) who reported positive association in wheat and negative association in spring barley, respectively, between grain yield and harvest index. grain yield was positively correlated with grain yield per plant (r = 0.23*) and negatively correlated with days to physiological maturity (r = -0.23*) (table 7). the current finding revealed that grain yield had no association with number of seeds per pod (r = 0.06), pod length (r = 0.06), grain filling period (r = 0.12) and hundred seed weight (r = -0.10). similar results were reported by kebere et al. (2006) who stated that there was no association among grain yields and number of seeds per pod, pod length and hundred seed weight. several authors also observed no association between grain yield and hundred seed weight (riggs et al., 1981; waddington et al., 1987; white and izquierdo, 1991; tarekegne, 1994; teklu, 1998). in contrast, positive correlations were recorded for grain yield with the number of seeds per pod and mean seed weight in soybean (karmakar and bhatnagar, 1996), with the number of grains per ear in wheat (waddington et al., 1987; perry and d’antuono, 1989). according to this finding, plant height (r = 0.45**), number of pods per plant (r = 0.44**), number of seeds per plant (r = 0.38**), harvest index (r = 0.60**), biomass production rate in kilogram per hectare per day (r = 0.68**), biomass yield in kg per hectare (r = 0.64**), seed growth rate in kilogram per hectare per day (r = 0.98**) and grain yield per day in kilogram per hectare (r = 0.99**) were highly correlated with grain yield (kg ha-1); so, plant breeders can possibly increase the final output by improving these characters, particularly the most interesting character, grain yield. according to this study, bean anthracnose severity had no association with grain yield for large-seeded food type common bean varieties. but, characters like grain filling period (r = 0.29**), biomass production rate in kilogram per hectare per day (r = 0.39**), biomass yield in kilogram per hectare (r = 0.40**) was highly correlated; while harvest index (r = -0.25*) negatively correlated with anthracnose severity; for the rest studied characters, anthracnose severity had no association (table 7). number of pods per plant and number of seeds plant (r = 0.91**), biomass yield in kilogram per hectare and biomass production rate in kilogram per hectare per day (r = 0.99**), seed growth rate in kilogram per hectare per day and grain yield in kilogram per day per hectare (r = 0.99**), grain yield in kilogram per day per hectare and grain yield in kilogram per hectare (r = 0.99**) and seed growth rate in kilogram per day per hectare and grain yield in kilogram per hectare (r = 0.98**) was strongly associated with each other in these large-seeded food type of common bean varieties during the study season. grain yield as a dependent variable, other unmentioned characters as independent variables and the stepwise regression analysis of the large-seeded food type of common bean varieties are tabulated hereunder (table 8). grain yield per day and days to physiological maturity were the most important characters that greatly contributed to the variation of grain yield of these common bean varieties (table 8). grain yield per day contributed 82.5%, while days to maturity contributed 21.8% of the total variations in grain yield. on the contrary, seed size and anthracnose severity contributed 40.2 and 9.3%, respectively, for the reduction of grain yield. solomon et al. east african journal of sciences volume 13(1) 15-26 24 table 8. summary of selection from stepwise regression analysis of mean grain yield of large-seeded food type common bean varieties as dependent variable on the other traits as independent variables independent variable grain yield in te rc e p ti o n r e g re ss io n c o e ff ic ie n ts (b ) r2 vif grain yield day-1 -1834 -0.643** 0.825 5.03 days to maturity 0.177** 0.218 5.03 seed weight 0.685** -0.402 4.07 anthracnose severity 0.395** -0.093 1.04 note: ** = significant difference at p < 0.01, r2 = coefficient of determination and vif = variance inflation factor 4. conclusion the averages over locations grain yield ranged from 1050.2 kg ha-1 for glp-2 variety to 2679.5 kg ha-1 for ayenew. the tested common bean varieties were found to be genetically different. the tested common bean varieties exhibited significant differences for most of the studied characters, and locations also exerted considerable effects on common bean varieties. however, the common bean variety by location interactions on anthracnose severity (%) from largeseeded food made crossover type of interaction as well or the different varieties performed in different way at different locations. the older released varieties were more stable and better adapted than the recent ones; grain yields of large-seeded food type common bean varieties were reduced by 48.06 kg ha-1 (0.39%) annually and 720.9 kg ha-1 (5.85%) in the period of genetic improvement for the past fifteen years. this is because most of the recent large-seeded food type common bean varieties are released for their type to export than yield production. relatively, better genetic progress was obtained from breeding large-seeded food type of common bean varieties in ethiopia in seed size and biomass yield than in grain yield, harvest index and anthracnose resistance for the last 15 years of breeding period. therefore, to bring drastic changes in these characters, appropriate breeding strategies should be devised for future research consideration to come up with effective yield gains like crossing. when we consider the past improvement, genetic progress made for large-seeded food type of common bean varieties decreased due to the consistent performance of the first released variety, gofta and the increase in seed size and anthracnose development as stepwise regression reflected. therefore, from stepwise regression point of view, grain yield per day would be praised by plant breeders to generate attractive yield; days to maturity also would be considered as well. the homework for the next investigator should be further identification of the important character(s) that contribute more to the variation of grain yield of common bean varieties and including well practicing of crossing for this crop. big seed size and anthracnose severity were considered as a reason for the reduction of the yield. therefore, even if big seed size of common bean has a contribution on the market, it has the problem on the reduction of the yield and disease development; especially, anthracnose disease will be considered for the next researcher. finally, among these evaluated large seeded food type common bean varieties, ayenew (26.79.5 kg ha-1), gofta (2627.1 kg ha-1) and fedis (2180.6 kg ha-1) will be recommended for the area. 5. acknowledgements this research was part of msc research work done by the first author at haramaya university under the supervision of the second, third and fourth authors. oromia agricultural research institute (oari) and bako agricultural research center (barc) are acknowledged for their financial support. melkasa agricultural research center (marc), haramya university (hu) and sirinka agricultural research center (sarc), are also praised for providing common bean varieties. finally, we wish to express our heartfelt gratitude to all individuals, who were involved directly or indirectly in the research activity, for the assistance and support they gave during the research work. 6. references ahmad, m., mohammad, f., maqbool, k., azam, a. and iqbal, s. 2003. genetic variability and trait correlation in wheat. sarhad journal of agriculture, 19 (3): 347-351. broughton, 2003. ‘bean (phaseolus spp.) – model food legumes.’ plant & soil, 252. csa (central statistical agency), 2014. agricultural sample survey 2013/14: report on area and production of crops (private peasant holdings, meher season). addis ababa, ethiopia. donmez, e., sears, r.g., shroyer, j. p. and paulsen, g.m. 2001. genetic gain in yield attributes of winter wheat in the great plains. crop science, 41:14121419. csa (central statistics agency of ethiopia) (2016) report on area and crop production of major crops for 2016 meher season, 1: 125. egli, d. b. 2008. soybean yield trends from 1972-2003 in mid-western usa. field crops research. 106: 53-59. evans, l. t. and fischer, r.a. 1999. yield potential: its definition, measurement, and significance. crop science, 39: 1544-1551. solomon et al. genetic progress of common bean for yield and reaction to bean anthracnose 25 fekadu, w, zeleke, h and ayana, a. 2011 genetic improvement in grain yield potential and associated traits of food barley (hordeum vulgare l.) in ethiopia. ethiopian journal of applied science and technology. 2(2): 43-60. ferris, s. and kaganzi, e. 2008. evaluating marketing opportunities for haricot beans in ethiopia. paper 7. in: ipms (improving productivity and market success) of ethiopian farmers project working ilri (international livestock research institute), nairobi, kenya. 68 gomez, k. and gomez, a. 1984. statistical procedurefor agricultural research. 2nd ed. international rice research institute. john wiley and sons inc. 680 pp. jin, j., liu, x., wang, g., mi, l., shen, zh, chen. x. and herbert, s.j. 2010 agronomic and physiological contributions to the yield improvement of soybean cultivars released from 1950 to 2006 in northeast china. field crops research. 115: 116-123. karmakar, g. and bhatnagar, s. 1996. genetic improvement of soybean genotypes released in india from 1969 to 1993. euphytica, 90: 95-103. kebere bezaweletaw, ketema belete and prapa sripichitt, 2006. genetic gain in grain yield potential and associated agronomic traits in haricot bean (phaseolu vulgaris l.). kasetsart journal (natural science), 40: 835-847. laing, d.r., jones, p.g. and davis, j.h.c. 1984. common bean (phaseolus vulgaris l.). pp. 305-351. in: p.r. goldsworthy and n.m. fisher (eds.). the physiology of tropical field crops, john wiley, new york, usa. 23: 91-105. little, t. m. and hills, f. j. 1978. agricultural experimentation: design and analysis. john wiley and sons, new york. 38: 273-452. meteorological data of bako agricultural research center (2014) moa (ministry of agriculture). 2014. ministry of agriculture, animal and plant health regulatory directorate. crop variety register issue no. 17, june 2014, addis ababa, ethiopia. morrison, m. j., voldeng, h. d. and cober, e. r. 2000 agronomic changes from 58 years of genetic improvement of short-season soybean cultivars in canada. agronomy journal. 92: 780-784. pastor-corrales, m. a. and tu, j. c. 1989. anthracnose. pp. 77-104. in: bean production problems in the tropics. 2nd ed. edited by h.f. schwartz and m.a. pastor-corrales, centro internacionale de agricultura tropical, cali, columbia. perry, m. w. and antuono, m. f. d'. 1989. yield improvement and associated characteristics of some spring wheat cultivars introduced between 1960 and 1982. journal of australian agricultural research, 50: 457-472. peter, j., sexton, j., white, j.,w. kenneth, w. and boote j., 1994. yield determining processes in relation to cultivar seed size of common bean. field crops res. 34: 8-91. riggs, t. j., hanson, p. r., start, n. d., miles, d. m., morgn, c. l. and dord, m. a. 1981 comparison of spring barley varieties grown in england and wales between 1880 and 1980. journal agricultural science. 97: 599-610. sas (statistical analysis system). 2009. salado-navarro, l. r., sinclair, t. r. and hinson, k. 1993. changes in seed yield and seed growth traits in soybean cultivars released in southern usa from 1945 to 1983. crop science, 33: 1204-1209. tarekegne, a. 1994. yield potential of rainfed wheat in the central highlands of ethiopia. msc thesis. alemaya university of agriculture, alemaya, ethiopia. 3: 41-59 teklu, y. 1998. genetic gain in grain yield potential and associated agronomic traits of tef (eragrostis tef (zuss) trotter). msc thesis. alemaya university of agriculture. alemaya, ethiopia. tesfaye, b. 1997. loss assessment study on haricot bean due to anthracnose. pest management journal of ethiopia 1: 69-72. waddington, s., ransom, s. osamanzi, m. and sounders, d. 1986. improvement in the yield potential of bread wheat adapted to northwest mexico. crop science, 26: 699-703. white, j.w. and izquierdo, j. 1991. physiology of yield potential and stress tolerance, pp. 287-382. in: a. van schoonhoven and o. voysest (eds.). common bean: research for crop improvement. c.a.b. international. nillingford, uk. wortmann, c.s., kirkby, r.a., eledu, c.a. and allen, d.j. 1998. atlas of common bean production in africa, ciat, cali, colombia. 133 pp solomon et al. east african journal of sciences volume 13(1) 15-26 26 ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2019) volume 13 (2) 113-120 ________________________________________________________________________________________________________________ licensed under a creative commons *corresponding author. e-mail: assefa.ayele50@gmail.com attribution-non-commercial 4.0 international license. technical efficiency of wheat production by smallholder farmers in soro district of hadiya zone, southern ethiopia assefa ayele1*, jema haji2, and bosena tegegne2 1southern agricultural research institute, areka agricultural research center, areka, ethiopia 2haramaya university, college of agriculture and environmental sciences, p. o. box 138, dire dawa, ethiopia abstract: productivity of what in ethiopia is below potential. this could be attributed to a number of factors among which is lack of knowledge on how to use new wheat crop production technologies. therefore, this study was conducted to estimate the technical efficiency of smallholder wheat producers and identify its determinants in soro district of hadiya zone, southern ethiopia. cross sectional data from a random sample of 125 wheat producing farmers were collected during the 2015/16 main production season and analyzed. a cobb-douglas production function and stochastic frontier analysis were employed to achieve the objectives. the results revealed that the mean technical efficiency of wheat producing farmers was 72%. the discrepancy ratio gamma (γ), which measures the relative deviation of output from the frontier level due to inefficiency, was about 63%. this implies that about 63% of the variation in wheat production among the sample farmers was attributed to technical inefficiency effect. the estimated inefficiency parameters showed that age, education level, land ownership, fertility status of the plots and extension contact negatively and significantly affected technical inefficiency of wheat production showing that an increase in the value of the variable attached to the coefficient means the variable negatively contributed to inefficiency level or conversely it contributed positively to efficiency levels. however, land fragmentation positively and significantly affected technical inefficiency showing that this variable has a negative influence on technical efficiency. keywords: cobb-douglas; soro; stochastic frontier analysis; technical efficiency; wheat. 1. introduction agriculture is the main economic pillar of the ethiopian economy. the sector accounts for about 36.3% of the gross domestic product (gdp), provides employment opportunities to more than 73% of total population that is directly or indirectly engaged in agriculture, generates about 70% of the foreign exchange earnings of the country and 70% raw materials for the industries in the country (undp, 2018). ethiopia is the largest wheat producer in sub-saharan africa and has a favorable climate for wheat production. wheat is the fourth important cereal crop in the country and predominantly grown by subsistence farmers under rain-fed conditions. however, , the country is reliant on foreign wheat imports to satisfy its annual domestic demand (fao, 2014). wheat is cultivated in the highlands of ethiopia, mainly in oromia, amhara, southern nations and nationalities peoples (snnp) and tigray regions and it is the first most important cereal crop in hadiya zone, especially soro district. according to the report of central statistical agency, for the crop year of 2015/2016, from the total land allocated for cereal crops, wheat stands in fourth by covering 13.33% of the total areas preceded by teff, maize, and sorghum. in the production year, the total area covered by wheat was 1.66 million hectares with a production of 42.19 million quintals and yield of 25.35 qt/ha from 4.78 million holders. despite the importance of wheat as a food and industrial crop and the efforts made so far to generate and disseminate improved production technologies, its productivity remains far below its potential. the average wheat yield was about 2.1 tons per hectare in 2012/2013 cropping season (csa, 2013). according to previous research conducted in ethiopia, there exists a wide cereal yield gap among the farmers that might be attributed to many factors such as lack of knowledge and information on how to use new crop technologies, poor management, biotic, climate factors and more others (sisay et al., 2015; ahmed et al., 2013; mesay et al., 2013). if the existing production system is not efficient, introduction of new technologies could not bring the expected improvements in the productivity of wheat and other crops. given the existing technology, improvements in the technical efficiency will enable farmers to produce the maximum possible output from a given level of inputs. hence, improvements in the level of technical efficiency will increase productivity. yet empirical data on the farm level technical efficiency is limited and level of knowledge of farmers’ on what production remain scantly known particularly in sub-saharan africa. hence, given that developing countries have scarce resources to undertake new investments on modern agricultural technologies, improving the technical efficiency of farmers is indispensable i.e. there is a wide room for increasing agricultural productivity and production in these areas by improving technical efficiency of farmers at the existing resources. therefore, from the perspective of formulating effective agricultural policies, undertaking research to generate empirical data on farm level technical efficiency has a paramount importance for providing valuable information to policy makers which will be used to enhance agricultural productivity. equally important is to examine the principal factors that affect technical efficiency of farmers since these factors can be influenced by public policies. in the study area, there is lack of pertinent research on technical efficiency of the smallholder farmers and the determinants of the variability in the efficiency levels among farmers. this study is aimed at assessing and analyzing the technical efficiency of the farmers in the study area and bridging the prevailing information gap on factors contributing to efficiency differences in wheat production. assefa et al. east african journal of sciences volume 13 (2) 113-120 114 2. research methodology 2.1. description of the study area the study was conducted in soro district. it is located in hadiya administrative zone in southern ethiopia and is lies between 7023'00'' and 70 46'00'' north latitude and 37018'00'' and 37023'00'' east longitude. the district has an altitude that ranges between 840-2850 meters above sea level. according to swado report, (2015/16) the district has three basic agro-climatic conditions, namely dega (cool) (14.2%), woyinadega (semi-cool) (53.1%) and kola (warm) (32.7%). the mean annual rainfall of the area is 1260 mm and the average temperature is 190c. farming system of soro is mixed crop-livestock farming. the main types of crops grown are wheat, teff, barley, maize, sorghum, etc. wheat is the most important crop grown in terms of area coverage and volume of production in the district. wheat, being one of the major crops grown in the study area, is mostly used as a staple food and source of income. figure 1: map of the study area. 2.2. data sources and sampling technique in this study, both primary and secondary data were used. the primary data were collected from randomly selected sample respondents using a structured questionnaire. in order to support primary data, secondary data were also collected from different published and unpublished documents about the study area from the district’s agricultural development offices, governmental and non-governmental agencies and websites. thus, purposive and twostage random sampling techniques were employed for this study. the study district was purposively selected based on the extent of wheat production. in the first stage, out of 28 major wheat producer kebeles, three kebeles were selected randomly. in the second stage, the lists of wheat producing farmers in the production year 2015/16 in the selected kebeles were identified in collaboration with woreda agricultural and development office experts. finally, 125 sample farm households were selected by a simple random sampling technique based on probability proportional to size (pps). the sample size for the study was determined based on becker (1997) that suggested the procedure of drawing an adequate sample size from a given population at 5 percent error and 95 percent confidence level. this is given by: maximum error of margin at 5% = where n is the minimum sample size to be drawn, z is the value corresponding to 95 percent level of confidence, and p* is the proportion that belongs to the target population out of total population. the population of wheat producing farmers in the 28 kebeles of the district is about 24,388 in which the size of wheat farmers in the three sample kebeles is about 8.95 percent and z-score that corresponds to the 95 percent level of confidence is 1.96. table 1. sample from the randomly drawn kebeles using pps. no name of kebele no. of wheat farmers sample size 1 kecha 1015 46 2 bure 820 38 3 sundusa 890 41 total 3 2,725 125 2.3. data analysis to achieve the objectives of the study, both descriptive and econometric methods were employed. accordingly, in the descriptive part, simple measures of central tendency, frequency and percentages are used to describe the socio-economic, demographic and institutional characteristics of the sample wheat farmers. the stochastic frontier production function and the inefficiency model are simultaneously estimated with the maximum likelihood method using the econometric software, frontier 4.1 computer programme. 2.4. econometric analysis efficiency measurements are usually done using frontier methodologies, which shift the average response functions to the maximum output or to the efficient firm. these methodologies are broadly categorized under two frontier models; namely parametric and non-parametric. first, they differ on assumptions of the distribution of the error term that represents inefficiency. second, they differ in the way the functional form is imposed on the data. parametric methods use econometric approaches to impose functional and distributional forms on the error term whereas the non-parametric methods do not (coelli et al., 1998). agricultural production is inherent to variability due to random shocks such as drought, weather, pest infection, fires, diseases, etc. furthermore, because many farmers are smallholders whose farm operations are managed by family members, therefore keeping of accurate records is not always a priority. thus, much data available on production are likely to be subject to measurement errors (tim and george, 1996). due to these errors and random shocks which makes variation in output the stochastic production frontier will be used for its key features that the disturbance term is composed of two parts, a symmetric and a one-sided component. the symmetric component captures the random effect outside of the control of the decision maker including the statistical noise contained in every empirical relationship particularly those based on crosssectional assefa et al. technical efficiency of smallholder wheat production 115 household survey data. the one-sided component captures deviations from the frontier due to inefficiency. therefore, the general stochastic frontier model developed independently by aigner et al. (1977) and meuse and ven den broeck (1977) in which an additional random error, (vi), is added to the non-negative random variable, (µi), is specified as follows: ) there are different functional forms to represent the production frontier. the two commonly used functional forms are cobbdouglas and translog, each having their merits and demerits. both models overwhelmingly dominate the applications literature in stochastic frontier and econometric inefficiency estimation (coeil et al., 2005). however, the work by kopp and smith (1980) confirmed that if the interest lies in measuring technical efficiency and not in the analysis of general structure of the production function, the functional form will have insignificant impact on measurement of efficiency. in order to identify the specific functional forms which will fit with our data, generalized likelihood ratio test was used. therefore, cobb-douglas was selected for this study. where: outp is the total output of wheat produced in quintal by the ith household; area is the total area covered by wheat in hectares of the ith household; lab the total labor force used for plowing, planting, weeding and cultivation which are all measured in terms of man-day; seed is the total quantity of wheat seed used by the ith household measured in kilogram; urea/dap is the total amount of urea/dap fertilizer in kilogram applied by the ith household for wheat production; oxpw the amount of draught power used for different farming activities for wheat production is measured in oxen day. herb-this is the total expenditure the farmer on herbicide purchase for wheat production and measured in birr. viis the disturbance error term, independently and identically distributed as n(0, σv2) intended to capture events beyond the control of farmers; and µi is a non-negative random variable, independently and identically distributed as n (µ, σµ2) intended to capture technical inefficiency effects in the production of wheat measured as the ratio of observed output to maximum feasible output of the ith household. the technical inefficiency effects model in which both the stochastic frontier and factors affecting inefficiency (inefficiency effect model) are estimated simultaneously is specified in equation (4) as a joint estimation of a stochastic frontier production function: 4) where the variables used in the above inefficiency model are defined as follows: µi is the inefficiency score of the ith household; δi is a vector of parameter to be estimated; wi is error term; the one-stage estimation procedure of the inefficiency effects model together with the production frontier function was used in the study. the two-stage procedure produces inconsistency in the assumption (coelli et al., 1998). moreover, one-stage procedure is the most commonly used method in the analysis of technical efficiency. thus one-stage procedure was selected for this study. the maximum likelihood estimates of the parameters of the frontier model are estimated, such that the variance parameters are expressed in terms of the parameterization; and (5) where the γ parameter has a value between 0 and 1. a value of γ of zero indicates that the deviations from the frontier are entirely due to noise, while a value of one would indicate that all deviations are due to technical inefficiency. σ2 is the variance parameter that denotes deviation from the frontier due to inefficiency; σv2 is the variance parameter that denotes deviation from the frontier due to noise σs2 is the variance parameter that denotes the total deviation from the frontier. in the prediction of firm level technical efficiencies, battese and coelli (1995) pointed out that the best predictor of exp (-µi) is obtained by: (6) where = ; 𝜙(.) is the density function of a standard normal random variables. for the frontier model defined by equation (5), the null hypothesis, that there are no technical inefficiency effects in the model is conducted by testing the null and alternative hypothesis h0: γ = 0 versus h1: γ > 0. the hypothesis involving γ are considered due to the fact that, the battese and cora (1977) parameterization was adopted for this study and the test must be performed as a onesided test because γ cannot take negative values. as a result, the one-sided generalized likelihood ratio test suggested by coelli (1995) should be performed when maximum likelihood estimation is involved. this test statistic requires the estimation of the model under both the null and alternative hypotheses. under the null hypothesis h0: γ = 0, the model is equivalent to the traditional average response function, without the technical inefficiency effect, ui. a number of tests were made in this study using the likelihood ratio (lr) test given by equation (7). lr=λ=-2 ln [l(h0) / l(h1)] (7) λ = -2[ln l(h0) – ln l(h1)] where, λ is the likelihood ratio (lr), l(h0) = the log likelihood value of the null-hypothesis; l(h1) = the log likelihood value of the alternative hypothesis; and ln is the natural logarithms. this test statistics is asymptotically distributed as a chi-square (or mixed chisquare) random variable with degree of freedom equal to the number of restrictions involved (coelli et al., 1998). assefa et al. east african journal of sciences volume 13 (2) 113-120 116 table 2. variables used in the inefficiency model and their expected sign. no variables description measurement expected sign 1 age age of the household head years 2 educ years of schooling of farm hh years -/+ 3 sex sex of farm hhh 1=male;0=female 4 fams number of family members working on farm number 5 totcult lnd total operational land holding ha -/+ 6 ferty fertility status of the soil 1=fert;0=otherwise 7 lives number of tlu number 8 exten farmers contact to extension service number 9 slop slope of the plot 1=plain;0=otherwise 10 credit harmer access and use of formal credit 1=access&use;0=otherwise 11 frag number of plots of all annual crops number + 12 ownl ownership of plots 1=owned&hired;0=otherwise 3. results and discussion 3.1. descriptive statistics the summary of the descriptive statistics related to the entire variables used for the analysis is presented as mean, minimum, maximum and standard deviation values for continuous variables and frequencies and percents for discrete variables (table 3). the results show that the average wheat output produced in the study area was 1315 kg. the land allocated for wheat production, by sampled farmers during the survey period was on average of 0.59 ha and the amount of seed that sample households used was on average 54.88 kg. the sample farmers on average applied 49.69 kg of dap, 46.60 kg of urea, 28.68 man-days, and 12.24 oxen days; and incurred birr 154.07 for cost of herbicide for the production of wheat during 2015/16 production season. average age of sample household heads was 44.1 years, average family size was 5.18 and educational level on average, was 3.33 years. the average land holding of the sample households in the district was 0.93 ha and a farmer on average has 2.25 plots with the number of plots varying from one to five. the livestock holding was measured in terms of tropical livestock unit (tlu) and sample farmers on average owned livestock of 3.74 tlu and average frequency of extension contacts during the production season was about 3.19 times. table 3. descriptive statistical for the variables used in the analysis continuous variables unit minimum maximum mean st. deviation output kg 200 4500 1315 986 seed kg 20 135 54.88 30.22 dap kg 15 130 49.69 29.90 urea kg 10 125 46.60 29.00 area ha 0.13 1.5 0.59 0.32 human labor man-days 15 62.50 28.68 11.82 oxen oxen day 2.50 31.63 12.24 7.29 herbicide birr 27 300 112.16 58.88 age years 25 72 44.12 10.46 education years 0 12 3.33 3.68 total cultivated land ha 0.25 3.5 0.93 0.66 fragmentation number 1 5 2.25 0.97 livestock tlu 1 18.1 3.74 2.64 family size number 2 9 5.18 1.58 extension frequency 0 7 3.19 1.66 discrete variables labels frequency percentage sex male=1 106 84.8 female=0 19 15.2 land ownership owned or rented=1 96 76.8 otherwise=0 29 23.2 fertility perception fertile=1 67 53.6 otherwise=0 58 46.4 slope plain=1 64 51.2 otherwise=0 61 48.8 credit used=1 79 63.2 not used=0 46 36.8 source: own computation (2016) assefa et al. technical efficiency of smallholder wheat production 117 3.2. econometric results 3.2.1. hypotheses testing one attractive feature of spf method is that it is possible to test various hypotheses using maximum likelihood test ratio. therefore, before presenting and discussing about parameter estimates of production frontier function and the inefficiency effects, it is advisable to run hypotheses tests in order to choose an appropriate model for further analysis and interpretation. tests of hypotheses for the parameters of the frontier model were conducted using the generalized likelihood ratio statistics, λ, defined by equation (7). accordingly, the following hypotheses were tested, namely to select the correct functional form for the given data set, for the existence of inefficiency and finally for variables that explain the difference in efficiency. the first null hypothesis was ho: γ = 0, which specifies that the inefficiency effects in the spf were not stochastic. the generalized likelihood ratio statistics, λ= 42.62, presented in table 4 is found to be greater than the critical value of 6.63. hence, we reject null hypothesis (ho) at 1% level of significance showing that the average response function is not an adequate representation of the data. the second test was the null hypothesis that identifies an appropriate functional form between restrictive cobb-douglas and the non restrictive translog production function which specifies that square and cross terms. the test result show that the calculated value of λ = 44.64 is less than the critical value of 48.27, thus the null hypothesis is not rejected at 1% level of significance implying that cobb-douglas functional form best fit the data set. table 4. generalized likelihood ratio tests of hypothesis for the parameters of the spf. null hypothesis df lho lh1 calculated χ2 (lr) value critical value (χ2, 0.01) decision ho: γ = 0 1 -7.47 35.15 42.62 6.63 reject ho: β8 = β9 = β35=0 28 35.15 57.47 44.64 48.27 not reject h0: ui =δ1= δ2= . . .= δ12=0 12 -6.17 35.15 82.64 26.21 reject source: own computation (2016) 3.2.2. input parameter estimates of the spf model the stochastic cobb-douglas production function maximum likelihood estimates of the parameters defined by equation 3 are presented in table 5. the diagnostic statistics of inefficiency component reveals that sigma squared (σ2) was statistically significant which indicates goodness of fit, and the correctness of the distributional form assumed for the composite error term. the estimated value of gamma (γ) is 0.63 which indicates that 63% of total variation in wheat output among sample farmers is due to technical inefficiency. in addition to this, the results showed that the estimated coefficients for dap, urea, oxen power, herbicide and area are all positive and significant which confirm that, these inputs significantly increase output. the mle values of the coefficients can be interpreted as elasticity of production. the coefficients of inputs indicate that on average a 1% increase in dap, urea, oxen power, herbicide and area increases the output of wheat by 0.13%, 0.17%, 0.29%, 0.12% and 0.48%, respectively. 3.2.3. technical efficiency scores the mean technical efficiency of the sampled wheat producer households in 2015/16 production year in the area was 72%, with minimum and maximum efficiency levels of about 37% and 96% respectively (table 6). this shows that there is a wide disparity among wheat producer farmers in their level of technical efficiency which in turn indicates that, there exists a room for improving the existing level of wheat production through enhancing the level of farmers’ technical efficiency. the mean level of technical efficiency further tells us that the level of wheat output of the sample respondents can be increased on average by about 28% if appropriate measures are taken to improve the level of efficiency of wheat growing farmers. in other words, there is a possibility to increase yield of wheat by about 28% using the resources at their disposal in an efficient manner without introducing any other improved (external) inputs and practices. table 5. mles for parameters of the cobb-douglas stochastic production function. variables coefficient standard-error t-ratio constant 5.09*** 0.62 8.16 lnseed -0.08 0.09 -0.82 lndap 0.13*** 0.05 2.57 lnurea 0.17*** 0.05 3.31 lnlabor 0.11 0.09 1.19 lnoxen 0.29*** 0.09 2.99 lnherbicide 0.12** 0.05 2.20 lnarea 0.48*** 0.13 3.52 diagnostic statistics sigma-squared (σ2) 0.06*** 0.08 4.86 gamma (γ) 0.63* 0.32 1.94 log likelihood function 35.15 source: own computation (2016) note: *, ** and *** significant at 10%, 5% and 1% significance level, respectively. assefa et al. east african journal of sciences volume 13 (2) 113-120 118 the next the null hypothesis that the explanatory variables associated with technical inefficiency effect model are all zero, (h0: ui=δ0 = δ1 = δ2 δ12 = 0). to test this hypothesis likewise, λ was calculated using the value of the log likelihood function under the stochastic frontier model (a model without explanatory variables of inefficiency effects, h0) and the full frontier model (a model with variables that are presumed to determine inefficiency of each farmer, h1). the calculated value of λ = 82.64 is greater than the critical value of 26.21, thus the null hypothesis that variables in the inefficiency effects model are simultaneously equal to zero is rejected at 1% level of significance. hence, these variables explain the difference in inefficiency among farmers. table 6. estimated technical efficiency scores. descriptive statistics technical efficiency scores mean 0.72 maximum 0.96 minimum 0.37 standard deviation 0.17 source: own computation (2016) 4.2.4. determinants of technical inefficiency the main interest behind measuring technical efficiency level is to know the factors that determine the technical efficiency level of individual farmers. the parameters of the various hypothesized variables in the technical inefficiency effect model that were expected to determine efficiency differences among farmers were estimated through mle method using one-stage estimation procedure. table 7 illustrates the socio-economic, demographic, farm characteristics and institutional factors that affect efficiency in wheat production. out of the twelve variables used, six variables (age, education, land fragmentation, land ownership, fertility status of the plot and extension contact) were found to affect significantly the efficiency of wheat farmers. the age of respondents has a significant negative effect on inefficiency of wheat producing farmers at 10% level of significance. this indicates that as the age of farmers increases their inefficiency reduces which leads to improvement in the level of technical efficiency. this may be due to the fact that age can serve as a proxy variable of farming experience, in which farmers with more years of experience are expected to be less inefficient. the result is in conformity with the results of endalkachew (2012) and shumet (2012) and in contradiction with the study by mesay et al. (2013). education was measured in years of formal schooling. as expected, the sign of education was negative and significant at 10% level of significance implying that less educated farmers are not technically efficient than those that are relatively better educated. hence, education can be a proxy variable for managerial ability of the farmer and improves the ability of the household to make informed decision about production inputs. educated farmers more often have better access to agricultural information and higher tendency to adopt and utilize improved inputs (like fertilizers and crop varieties) more optimally and efficiently. this result is in line with results of the studies by endrias et al. (2013) and mesay et al. (2013). land fragmentation was hypothesized that plots in the area are highly fragmented and scattered over many places that would make undertaking farming activities on time and efficiently difficult. the positive and significant value of the coefficient of fragmentation in table 7 at 1% level of significance is consistent with the previous expectation. this may be because if the number of plots operated by the farmer increases, it may be difficult to manage these plots. thus, farmers that have a large number of plots may waste time in moving between plots. this finding is in line with empirical findings of fekadu (2004) and wondimu (2010). table 7 shows land ownership measured in terms of dummy, which was found to determine the efficiency level of farmers in producing wheat positively and significantly at 1% of significance. farmers who used their own land or hired land for wheat production were more efficient than farmers who managed sharecropped land. this may be due to the fact that operator farmers might not perform each farming activity on time especially during peak periods. in addition, the sharecropping arrangement would not encourage the operator farmer to take risk as the risk on loss of returns on inputs is solely taken by the operator farmer. the result is consistent with the results obtained by fekadu (2004). as can be seen from table 7, perceived soil fertility had a significant and positive impact on technical efficiencies at 10% level of significance. this implies that farmers having fertile land were more efficient than those who have less fertile land. this may be associated with the fact that fertile lands require application lower amounts of fertilizers which leads to reduction in cost and time, leading to reduction in the inefficiency of farmers. this result is similar with the findings reported by shumet (2012), hassen et al. (2014) and hailemaraim (2015). finally, the results showed that extension contact determined the inefficiency level of farmers negatively and significantly at 5% level of significance. this is consistent with the priori expectation that the more the farmer has extension visits, the less he/she will become inefficient. the improvement in the production system of wheat in the study area is one of the major focuses of extension. in the study area, the contact farmers had with extension workers played a significant role in improving the level of technical efficiency. the findings are consistent with earlier results of berhan (2013). table 7. maximum likelihood estimates of the factors determining technical inefficiency. inefficiency variable coefficien t standarderror t-ratio constant 0.90*** 0.18 4.84 age -0.05* 0.02 -1.91 sex -0.06 0.07 -0.90 education -0.02* 0.09 -1.84 total cultivated land 0.02 0.04 0.55 land fragmentation 0.07*** 0.03 2.87 land ownership -0.13*** 0.05 -2.35 fertility -0.18* 0.07 -2.69 slope -0.02 0.05 -0.44 livestock -0.02 0.01 -0.18 family size -0.01 0.02 -0.85 credit -0.04 0.05 -0.90 frequency extension contact -0.04** 0.02 -2.17 source: own computation (2016) assefa et al. technical efficiency of smallholder wheat production 119 note: *, ** and *** significant at 10%, 5% and 1% significance level, respectively 4. conclusions the results of this study demonstrated that that the traditional average response function is not an adequate representation of production frontier. the study revealed that a significant proportion of the variation in the stochastic frontier production function was due to technical inefficiency. this implies that there is a room for improvement in output through improving the inefficiency of farmers. the mean technical efficiency level of 72 percent indicates that production can be increased by 28 percent. hence, if inputs are used to their maximum potential, there will be considerable gain from improvement in technical efficiency. the estimated spf model together with the inefficiency parameters showed that age of farmers, education level, land ownership, soil fertility, and frequency of extension contact had a negative and land fragmentation had a positive and significant influence on the inefficiency of farmers. these factors have important policy implications for mitigating the existing level of inefficiency of farmers in the production of wheat and other crops, and hence, development programs should exploit these variables. therefore, the results of this study have relevance for policy makers on how to improve the technical efficiency and optimal use of resources for crop production in the study area. the following general policy recommendations could be drawn based on the results of the study. first, the local government should arrange field days, crossvisits, creating forum for experience sharing elder households and provision of short-term training programs so as to share the knowledge of elder households to young farmers. second, it is important to give due attention for farmers education through strengthening and establishing both formal, informal type of farmers' education by using the available human and infrastructural facilities like extension agents and farmers training centers. third, development programs need to strengthen improved land management practices to improve and maintain the fertility of farm land to increase efficiency of farmers. the result reveals that there is land shortage in the study area as a result of high population pressure. hence, serious intervention is required for intensive and efficient use of farming practices by improving the fertility of land and by adopting other improved crop production technologies. fourth, given the existing technologies at hand, bringing farmers under extension contact and rendering them the necessary advisory services can enhance the level of their technical efficiency in wheat production. fifth, land policy that would increase the ownership right would not only increase the efficiency of farmers but also increase the use of improved technologies since it minimizes the risk aversion behavior of farmers to invest on technologies. finally, farmers that operate a larger number of plots are less efficient than others. this implies that land policy that favors unfragmented land holding increases the efficiency of farmers. 5. acknowledgments this paper has emanated from msc research work done at haramaya university by the first author. the authors express their gratitude to global development network (gdn) for funding the research work through the project known as building ethiopia’s research capacity in economics and agribusiness (bercea) and also thank haramaya university for facilitating the research financial grant, training monitoring and evaluations of the research works. secondly, the authors thank soro woreda of agriculture and development office and farmers who participated in the study and provided the required data. 6. references aigner, d. j., lovell, c. a. k and schmidt, p. 1977. formulation and estimation of stochastic models. journal of econometrics, 6(1): 21-37. battese, g. e. and cora, g. s., 1977. estimation of a production frontier model: with application to the pastoral zone of eastern australia. australian journal of agricultural economics, vol. 21, pp. 169-179. battese g.e. and coelli, t.j. 1995. a model for technical inefficiency effects in a stochastic frontier production function for panel data. empirical economics, 20: 325 332. becker, w.e. 1997. statistics for business and economics using microsoft excel 97. indiana university s.r.b. publishing, bloomington, indiana. berhan tegegne. 2013. analysis of technical efficiency in onion production under irrigation conditions: the case of smallholders in kobo woreda of amhara region, ethiopia. m.sc. thesis, haramaya university, haramaya, ethiopia. beyan ahmed, jema haji and endrias geta. 2013. analysis of farm households' technical efficiency in maize production of smallholder farmers: the case of girawa district, ethiopia. journal of agriculture and environmental science, 13(12): 1615-1621. coelli, t. j., 1995. 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(http://www.fao.org/fileadmin/templates/.../ethiopia/.../ethiopi a_wheat_web.pd) (accessed on may 15, 2015). http://www.fao.org/fileadmin/templates/.../ethiopia/.../ethiopia_wheat_web.pd http://www.fao.org/fileadmin/templates/.../ethiopia/.../ethiopia_wheat_web.pd assefa et al. east african journal of sciences volume 13 (2) 113-120 120 fekadu gelaw. 2004. analysis of technical efficiency of wheat production: a study in machakel woreda, ethiopia. m.sc. thesis, haramaya university, haramaya, ethiopia. hailemaraim leggesse. 2015. technical efficiency in tef production: the case of bereh district, oromia national regional state, ethiopia. m.sc. thesis, haramaya university, haramaya, ethiopia. hassen nurhussen, adam bekele and jema haji. 2014. analysis of technical efficiency of haricot bean production in misrak badawacho woreda, hadiya zone, ethiopia. science, technology and arts research journal, 4(1): 234-241. kopp, r.j. and smith, v.k. 1980. frontier production function estimates for steam electric generation. a comparative analysis. southern economic journal, 47: 1049–1059. meeusen and j.van den broeck. 1977. efficiency estimation from cobb-douglas production function with composed error. international economic review, 18: 435-444. mesay yami, tesfaye solomon, bedada begna, fekadu fufa, tolesa alemu and dawit alemu. 2013. sources of technical inefficiency of smallholder wheat farmers in selected waterlogged areas of ethiopia: a translog production function approach. african journal of agricultural research, 8(29): 39303940. shumet asefa. 2012. analysis of technical efficiency of crop producing smallholder farmers in tigray, ethiopia. mpra paper no. 40461. (http://mpra.ub.unimuenchen.de/40461/) (accessed on july 27, 2015). sisay debebe, jema haji, degye goshu and abdi-khalil endriss. 2015. technical, allocative, and economic efficiencies among smallholder maize farmers in southwestern ethiopia: parametric approach. journal of development and agricultural economics, 7(8): 282-291. swado (soro woreda agricultural development office). 2015. crop extension profile of the soro district.of hadiya zone, soro, southern ethiopia. tim c. and george, b. 1996. identification of factors which influence the technical inefficiency of indian farmers. austria journal agricultural. economics. 40(2):103-128. undp (united nations development programme). 2018. ethiopia's progress to warding eradicating poverty. paper to be presented to the inter-agency group meeting on the implementation of the third united nations decade for the eradication of poverty (2018-2027) addis abeba, ethiopia. wondimu sakita. 2010. economic efficiency of export oriented crop production in ethiopia: the case of haricot beans in adama and dugda districts, east shewa zone of oromia, ethiopia. m.sc. thesis, haramaya university, haramaya, ethiopia. http://mpra.ub.unimuenchen.de/40461/ east african journal of sciences (2019) volume 13 (1) 65-74 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: ngusufekade@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) effects of replacing maize with kocho in white leghorn layers ration on egg production, egg and chick quality, fertility and hatchability nigussu fekade1*, mengistu urge2, ajebu nurfeta3, and getachew animut4 1department of animal sciences, assosa university, p. o. box 18, assosa, ethiopia 2school of animal and range sciences, haramaya university, p.o. box 138, dire-dawa, ethiopia 3school of animal and range sciences, hawassa university, p.o. box 5, hawassa, ethiopia 4agricultural transformation agency, p.o.box 708, addis ababa, ethiopia abstract: one hundred and eighty 26-week old white leghorn layers were used to evaluate the effect of replacing maize with kocho on egg production, egg and chick quality as well as fertility and hatchability. the layers were fed with ration containing kocho at the levels of 0% (t1), 33% (t2), 67% (t3) and 100% (t4) replacing white maize grain in the ration. the experiment was arranged in a completely randomized design with four treatments, each replicated three times with 15 birds each. the experiment lasted 12 weeks. hens were weighed at the start and end of the experiment. data on dry matter intake, hen day egg production (hdep), egg weight and egg mass were recorded daily. egg quality parameters (egg shell weight and thickness, albumen weight and height, haugh unit and yolk weight as well as color) were determined at the interval of 7 days on 4 eggs per replicate. kocho contained 3663 kcal/kg dm, 3.8% cp, 2.5% ether extract, 2.3% crude fiber and 1.5μg/100g beta-carotene. highly significant (p<0.05) dry matter intake (140.2, 136.9, 133.4 and 152.4 g for t1, t2, t3 and t4). respectively, and average daily gains (1.93, 2.02, 1.91, 1.96 g) were recorded for t4. egg mass, egg weight and feed conversion ratios were statistically similar (p>0.05) among treatments. hdep for t3 (53.83 %) and t4 (53.62%) was similar and significantly (p < 0.05) higher than t1 (40.54%) and t2 (43.19%). egg quality characteristics, except yolk color were similar (p > 0.05) among treatments. yolk color was higher (p < 0.05) for t1 compared with t3 and t4. percent hatchability on fertile egg bases for t4 was significantly (p<0.05) lower than the remaining treatments while t2 and t3 were similar. mid embryonic mortality was significantly (p < 0.05) higher for t4 compared to the rest of the treatments but t2 and t3 had similar values. the lowest (p < 0.05) late embryonic mortality was recorded for t1. fertility, early and pipe embryonic mortalities, chick weight, chick length and yield percentage were similar (p > 0.05) among treatments. the partial budget analysis indicated that replacement of maize with 67% (t3) kocho gave a higher net return. therefore, kocho can replace maize in layers ration when there is scarcity of maize in enset growing areas of ethiopia. keywords: egg production; fertility; hatchability; kocho, layers 1. introduction poultry production plays an important role in ethiopia’s economy. it renders a significant contribution to household income and food security particularly in providing animal protein to the people (gondwe, 2004). however, the productivity per unit of bird and the contribution of this sector to the national economy is relatively low in ethiopia. feed scarcity and consequent high price of conventional energy and protein sources are factors that limit the productivity of poultry in ethiopia (aberra et al., 2011). compared to other animals, feed resources for commercial poultry production are grains of good quality, which also are used as human food. this put the sector in a direct competition for grains which leads to increased cost of poultry production (gura, 2008). ethiopia is endowed with diverse agro-climatic conditions favoring production of many different kinds of crops, providing a wide range of alternative feedstuffs suitable for poultry feeding (tadelle et al., 2002). one of such crop is enset (ensete ventricosum). ensete ventricosum (welw.) (cheesman, musaceae) is a monocarpic short-lived perennial plant which is cultivated in the central, south and south-western parts of ethiopia, where an estimated 35% of the total population of ethiopia lives and the plant is used as one of the staple food in these areas (csa, 2014). the pseudo-stem, corm and the stalk of inflorescence constitute the most important components of enset (adugna, 2008). over 70% of the enset plant is composed of pseudostem and corm (ajebu et al., 2008). the major food products obtained from the enset plant are kocho, bulla and amicho. kocho is bulky, fermented starch, made from a mixture of the decorticated pseudostem and grated root fermented with yeast, in a traditionally dug out pit (admasu, 2002). as indicated by tsegaye (2001) kocho has high carbohydrate (96%) the content even more than maize (83%). according to admasu (2002) kocho yield of enset per unit of space and time, in terms of edible dry weight and energy was much higher than the yields of any other crops cultivated in ethiopia. kocho could be produced throughout the year and hence is available year round unlike that of maize and it can be stored for a long period of time without spoiling. earlier work shows that substitution of maize with kocho up to 100% resulted in similar dry matter intake, average daily gain, and carcass yield of hubbard broiler chicks (ajebu et al., 2015) and could be used as an alternative ingredient to replace maize in the diet of sheep (ajebu et al., 2012). however, there is scarcity of information regarding the effect of feeding kocho mailto:ngusufekade@gmail.com nigussu et al. east african journal of sciences volume 13 (1) 65-74 66 on performance and egg quality of layer chickens. therefore, the present experiment was conducted to evaluate the effect of replacing kocho for maize on egg production, egg and chick quality, fertility and hatchability of white leghorn layers. 2. materials and methods 2.1. description of the study area the experiment was conducted at haramaya university poultry farm, located at 42° 3’ east longitude, 9° 26’ north latitude, at an altitude of 2006 meters above sea level. the mean annual rainfall of the area was reported to be 780 mm and the average minimum and maximum temperature are 8 and 24°c, respectively (samuel, 2008). 2.2. experimental feeds preparation enset plants of age 4-6 years of “ashakti” variety were bought from farmers in daryan kebele, south west shewa zone, oromia regional state, ethiopia. the pseudo-stem and corm were pulverized with a long wooden (bamboo) pestle and pound into a pulp from which the fibers were removed. the remaining scrapings, the pulp, and the inner core were kneaded together, rolled into balls, and wrapped in a fresh enset leaves. the leaf packages with fresh enset mash were packed into a pit in the ground that has been completely lined with leaves and left to ferment for fifteen days (asres and omprakash, 2014). the fibre of wet kocho was separated by hand. then the wet kocho was spread over plastic sheet to sundry until it becomes safe for storage. feed ingredients used to formulate the rations for the study were kocho, maize grain, wheat short, soybean meal, noug seed cake, salt, vitamin premix and dicalcium phosphate (table 1). maize, noug seed cake and salt were ground at haramaya university feed mill to pass through 5mm sieve before mixing to formulate the rations. the feed ingredients used for the experiment (except kocho) were purchased from local market. the treatment rations used in the present study were formulated to be nearly isocaloric and isonitrogenous with 2800 kcal me/kg dm and 16.0% cp to meet the nutrient requirements of layers (leeson and summers, 2005). kocho was included into the treatment ration to replace 0, 33, 67, and 100% of maize for t1, t2, t3 and t4, respectively. table 1. proportion of the feed ingredients used in formulating layers rations. ingredients treatments t1 t2 t3 t4 maize 43.5 29 14.5 0 kocho 0 14.5 29 43.5 wheat short 17 17 13 10 noug cake 17 17 17 17 soybean meal 14 14 18 21 vitamin premix* 1 1 1 1 salt 0.5 0.5 0.5 0.5 lime stone 6.5 6.5 6.5 6.5 dicalcium phosphate 0.5 0.5 0.5 0.5 total 100 100 100 100 note: t1 = 0% kocho; t2 = 33% kocho; t3 = 67% kocho; t4 = 100% kocho as replacement to maize; *vitamin premix 50 kg contains, vit a = 2000000iu, vit d3 = 400000 iu, vit e = 10000 mg, vit k3 = 300 mg, vit b1 = 150 mg, vit b2 = 1000 mg, vit b3 = 2000 mg, vit b6 = 500 mg, vit b12 = 4 mg, vitpp = 60000 mg, folic acid = 160 mg, choline chloride = 30000 mg, anti-oxidant = 500 gm, manganese = 10000 mg, zinc = 14000 mg, iron = 9000 mg, copper = 1000 mg, iodine= 200 mg, selenium = 80 mg, calcium = 28.2%. 2.3. experimental animals management and experimental design a total of 180 white leg horn pullets with body weight of 1.13±0.06kg (mean±sd) and age of 26 weeks were used for the experiment. pullets used in the study were obtained from haramaya university poultry farm. pullets were grown with feed containing 20% cp and 2800kcal/kg dm me during starter phase and 16% cp and 2700kcal/kg dm me during the grower phase. before placing the pullets into the experiment house, the experimental pens, watering and feeding troughs and laying nests were thoroughly cleaned, disinfected and sprayed against external parasites. the floor of the pens was covered with disinfected sawdust. the pullets were vaccinated against newcastle, gumburo and fowl typhoid diseases using appropriate vaccine according to the manufacturer’s recommendation. vitamins were given as vitamin premix mixed in the diet. each pen was equipped with individual laying nests, covered with saw dust. the wet litter was changed with dry, disinfected and clean sawdust whenever required. the birds were randomly allocated to four dietary treatment groups in a crd design. each treatment has three replicates comprising 15 pullets and 2 cocks per replicate. each pen has a 2 x 2.4m wire mesh partitioned pens. twenty four cocks were randomly and equally distributed to each replication. during the twelve weeks period of the study, the birds were subjected to similar managerial and sanitary conditions. 2.4. feed intake and laying performance of hens feed was offered ad libitum with 10% refusal twice per day at 0800 and 1700hours and clean tap water was available all the time. the amount of feed offered and refused per pen was recorded daily, and the amount consumed was determined as the difference between the two. feed offered and refused were sampled daily per pen and pooled per treatment for the entire experimental period for chemical analysis. hens were individually weighed at the start and end of the experiment and body weight change was calculated as the difference of the two weights. eggs laid in a pen were collected three times a day at 0800, 1300 and 1700hours. eggs collected daily were weighed immediately after collection for each pen and average egg weight was computed by dividing the total egg weight to the number of eggs. egg mass per hen was calculated as total egg weight divided by number of hens. hen-day egg production was determined according to hunton (1995). feed conversion ratio was calculated as gram of eggs produced per gram of feed consumed. 2.5. egg quality characteristics egg quality parameters, such as egg shell weight, egg shell thickness, albumen weight, albumen height, egg yolk weight and egg yolk color were determined at an interval of 7 days on freshly laid 4 eggs per replicate after breaking and separating each of the components. egg shell, albumen and yolk weights were measured using sensitive balance. albumen and yolk nigussu et al. replacing maize with kocho in white leghorn layers ration 67 height were measured with a tripod micrometer. egg shell thickness was measured by eggshell thickness micrometer gauge. measurements of egg shell thickness were taken from three regions (large end, small end and on the equator region of the eggshell) and the average value was taken. yolk color was determined by comparing the color of properly mixed yolk sample placed on white paper with the color strips of roche fan measurement, which consist 1-15 strips ranging from pale to orange yellow color. haugh unit was calculated from the egg weight and albumen height using the formula suggested by haugh (1937). egg and yolk shape indexes were computed according to penda (1996). 2.6. fertility, hatchability and chick quality the eggs for incubation were collected towards the end of the study and stored for 7 days at a 10-14oc. good shape, clean shell, no cracks, medium or average sized eggs (50 eggs for each replication) were selected and used for incubation. the eggs were candled on the 9th day of incubation for the determination of percentage fertility. average percentage hatchability of the fertile eggs was computed by dividing the number of chicks hatched by the number of fertile eggs. early, mid, late and pipe embryonic mortalities were determined from the incubated eggs at 9th, 14th, 18th and on the last days of incubation, respectively by breaking all unhatched eggs with respective replicate using the method of bonnier and kasper (1990). chick quality was determined according to molenaar et al. (2009) and chick length was determined according to the method of meijerhof (2005). chick weight at hatching was determined by weighing the chick after 12 hours of hatching (molenaar et al., 2009). yield percentage evaluates the weight loss during incubation and was calculated as the percentage of average chick weight to average initial weight of egg set (molenaar et al., 2009). 2.7. economic evaluation partial budget analysis developed by upton (1979) was applied to estimate the economic benefits of each treatment ration. market price of each feed ingredients were registered at the time of purchase and feed consumed by birds were multiplied by the cost of the ingredient. total return (tr) was calculated as a total egg produced multiplied by price of egg at haramaya university during the experiment period. net return (nr) = tr-tvc (total variable cost, in this case feed cost). change in total variable cost (∆tvc) was calculated as total feed cost of treatments containing kocho (termed as experimental ration) minus total feed cost of treatments without kocho (control). the change in tr (∆tr) was calculated as the difference between total incomes from the respective experimental treatments minus total income of the control. change in nr (∆nr) was calculated as nr of the respective experimental treatments minus nr of the control experiment. the marginal rate of return (mrr) measures ∆nr associated with each additional units of expenditure (∆tvc). it is calculated as: mrr = ∆nr/∆tvc. 2.8. feed chemical analysis dried feed samples were milled to pass through 1 mm screen for chemical analysis. samples were analyzed for dry matter, crude protein, ether extract, crude fibre and ash following the proximate method of analysis (aoac, 1990). calcium and total phosphorus content was analyzed by atomic absorption and vanado-molybdate method, respectively (aoac, 1990) and beta-carotene content of kocho was determined by spectrophotometer (aoac, 1998). metabolisable energy (me) content of the experimental diets was calculated by indirect method from the equation proposed by wiseman (1987) as follows: me (kcal/kg dm) = 3951 + 54.4ee 88.7cf 40.8 ash. 2.9. statistical analysis data was analyzed using the general linear model procedure of statistical analysis systems software (sas, 2009). differences between treatment means were separated using tukey kuramer test. the following model was used for data analysis. yij = μ + ti + eij, where: yij = represents the jth observation in the ith treatment level, μ = over all mean, ti = treatment effect and eij = random error. the effect was considered significant at p< 0.05. 3. results 3.1. chemical composition of the feeds the cp content of kocho was the lowest compared with other ingredients (table 2). the me content of kocho was higher than other ingredients, except maize grain which had almost similar value. phosphorus content of kocho was lower than any other ingredients used to formulate treatment diets. table 2. chemical composition (% dm) of the feed ingredients and treatment diets. note: dm= dry matter; cp= crude protein; ee= ether extract; cf= crude fibre; t1 = 0% kocho; t2 = 33% kocho; t3 = 67% kocho; t4 = 100% kocho as replacement to maize; ca = calcium; p = phosphorous; me =metabolizable energy (kcal/kg dm); nd=not determined ingredients and treatments dm (%) ash cp ee cf me ca p beta-carotene (µg/100 g) kocho 86.3 5.8 3.8 2.5 2.3 3647 0.5 0.06 1.5 maize 92.4 3.2 9.3 3.9 3.8 3657 0.1 0.30 nd wheat short 91.8 4.6 15.7 3.3 7.8 2664 0.1 0.30 nd noug cake 92.7 13.0 31.8 8.2 15.2 2518 0.3 0.60 nd soyabean meal 91.9 6.1 44.7 4.9 12.6 2660 0.3 0.70 nd t1 92.8 15.8 16.5 3.6 6.9 2893 2.09 0.35 nd t2 91.8 16.9 16.9 3.9 7.3 2827 2.12 0.33 nd t3 91.7 17.0 16.9 4.0 7.4 2820 2.22 0.37 nd t4 89.6 13.3 15.8 4.4 8.8 2868 2.23 0.31 nd nigussu et al. east african journal of sciences volume 13 (1) 65-74 68 table 3. dry matter intake, body weight change and egg laying performance of white leghorn hens fed kocho as a replacement to maize. variables treatments sem p value t1 t2 t3 t4 dm intake (g/hen/d) 130.1b 125.7b 122.3b 136.5a 3.49 0.001 initial body weight (kg) 1.15 1.09 1.14 1.14 0.01 0.342 final body weight (kg) 1.31 1.26 1.30 1.30 0.05 0.246 body weight gain (g/hen/day) 1.93 2.02 1.91 1.96 0.10 0.640 hen-day egg production (%) 40.54b 43.19b 53.83a 53.62a 1.88 0.027 egg mass (g/hen/day) 15.15 15.65 20.73 22.21 0.74 0.054 egg weight (g) 51.13 51.42 51.36 52.12 0.38 0.627 fcr (g feed dm/g egg) 3.04 2.76 2.71 2.72 0.04 0.442 mortality rate (%) 7.89 note: a,b means within a row with different superscripts differ (p<0.05); t1 = 0% kocho; t2 = 33% kocho; t3 = 67% kocho; t4 = 100% kocho as replacement to maize; dm=dry matter; sem = standard error of the mean; fcr= feed conversion ratio replacement to maize. table 4: egg quality characteristics of white leghorn hens fed kocho as a replacement to maize egg quality parameters treatment sem p value t1 t2 t3 t4 sample egg weight (g) 51.1 51.8 51.42 51.12 0.41 0.558 egg length (mm) 54.4 54.4 54.5 55.5 0.02 0.449 egg width (mm) 41.7 40.7 40.4 40.1 0.61 0.099 egg shape index 73.82 74.73 74.00 72.40 11.35 0.830 egg shell weight (g) 6.04 5.92 5.95 5.63 0.07 0.235 egg shell thickness (mm) 0.322 0.301 0.294 0.293 0.00 0.115 egg albumen weight (g) 29.78 30.91 30.55 30.07 0.27 0.537 albumen height (mm) 8.06 8.40 8.18 8.12 0.13 0.857 haugh unit 91.50 93.02 92.14 92.01 0.74 0.932 egg yolk weight (g) 15.31 15.03 14.92 14.42 0.15 0.178 egg yolk height (µm) 15.23 15.10 15.04 13.99 0.22 0.165 egg yolk diameter (mm) 4.79 4.81 4.84 4.92 0.31 0.321 egg yolk index 0.32 0.32 0.31 0.30 0.22 0.345 yolk color (rsp*) 3.97a 3.75ab 3.55b 3.08c 0.09 0.003 note: a,b,c means within a row with different superscripts differ (p<0.05); t1 = 0% kocho; t2 = 33% kocho; t3 = 67% kocho; t4 = 100% kocho as replacement to maize ; *rsp = roche scale points; sem = standard error of mean table 5: fertility, hatchability and chick quality characteristics of white leghorn hens fed kocho as a replacement for maize. parameters treatments sem p value t1 t2 t3 t4 fertility (%) 99.73 99.35 97.93 97.98 0.43 0.674 hatchability on fertile egg bases (%) 84.66a 76.97b 72.22b 66.96c 2.37 0.036 early embryonic mortality (%) 2.91 2.92 4.11 6.63 0.80 0.458 mid embryonic mortality (%) 3.46c 5.22b 5.51b 7.47a 0.53 0.030 late embryonic mortality (%) 4.21b 4.62b 9.71a 11.51a 1.10 0.008 pipe embryonic mortality (%) 5.63 9.53 8.89 7.97 1.10 0.678 chick weight (gm) 33.70 33.87 32.56 33.60 0.34 0.571 yield percentage 52.90 49.73 42.79 41.57 1.88 0.068 chick length (cm)and 15.08 14.78 14.50 14.75 0.12 0.412 note: a,b,c means within a row with different superscripts differ (p<0.05); t1 = 0% kocho; t2= 33% kocho; t3 = 67% kocho; t4 = 100% kocho as replacement to maize; sem = standard error of mean. 3.2. feed intake and laying performance of hens the dm intake and body weight gain of hens fed t4 diets were higher (p<0.05) than other treatments while hens consumed t1, t2 and t3 diets did not differ in (p>0.05) dm intake and body weight gain (table 3). hen-day egg production for t3 and t4 was higher (p<0.05) than those nigussu et al. replacing maize with kocho in white leghorn layers ration 69 fed t1 and t2 diets. egg mass and egg weight were similar (p>0.05) among treatments. lower feed conversion ratio was observed for layers on t3 and t4 than on control diet while layers fed t2 had similar value with t3 and t4 diets. 3.3. egg quality characteristics egg quality characteristics, except yolk color were similar (p>0.05) among treatments (table 4). yolk color was in the order of t1 > t3 > t4 (p<0.05), while the value for t2 was similar with t1 and t3 but was higher than t4. table 6: economics of feeding kocho to white leghorn as replacement to maize. treatments total cost t1 t2 t3 t4 total feed consumed/ head (kg) 11.7 11.5 11.2 12.8 total feed cost/head (birr) 66.5 69.1 67.8 73.0 total variable cost (feed cost) (birr) 66.5 69.1 67.8 73.0 ∆tvc (birr) 2.6 1.3 6.5 total revenue total number of egg produced/hen 35.0 39.0 41.0 40.0 total return (tr)(birr) 87.5 97.5 102.5 100.0 ∆tr (birr) 10.0 15.0 12.5 net return( nr) (birr) 21.0 28.4 34.7 27.0 ∆nr (birr) 7.4 13.7 6.0 mrr (%) 2.8 10.5 0.9 note: ∆tvc = change in total variable cost; ∆tr= change in total return; nr=net return; ∆nr=change in net return; mrr = marginal rate of return; birr= ethiopia’s unit of currency: us $ 1.00= birr 22.00; egg sale = 2.5 birr/egg; t1 = 0% kocho; t2 = 33% kocho; t3 = 67% kocho; t4 = 100% kocho as replacement to maize 4. discussion 4.1. chemical composition of feeds the cp content of kocho (3.8%) in the present study was higher than the values (2.7%, 2.6%, 1.8% and 1.5%) reported by ajebu et al. (2012) for different varieties of kocho. higher cp (4.76%) content of kocho was reported by melese (2013) compared with the current experiment. the pseudo stem of 3-selected enset varieties on average was reported to have 7.2 (%cp) (fekadu and ledin, 1997). the difference in cp content may be due to difference in enset varieties from which kocho is produced. ajebu et al. (2008) observed varietal difference in cp content of unprocessed corm and pseudostem from which kocho is produced. melese (2013) noted fermentation time as a factor to increase the cp content of kocho. the me content for kocho noted in the present study is lower than the values of 3800 kcal/kg dm reported by tsegaye (2001) but higher than the 2111kcal/kg dm reported by tilahun et al. (2004). mohammed et al. (2013) also reported 3437 and 3379kcal/kg dm for unprocessed corm and pseudostem, respectively. the cf content (2.3%) of kocho is low as compared to the unprocessed corm (5.65%) and pseudostem (7.51%) reported by mohammed et al. (2013) but within the range of 1.47-4.42% reported by melese (2013) for different enset varieties. method of processing might have been contributed to the relatively low cf content of kocho. the relatively low level of cf in kocho and high level of me is indicative of its potential as a diary ingredient in layers ration. beta-carotene content of kocho (1.5µg/100g) is lower as compared to feed ingredients known for good beta-carotene content such as golden whole kernel and yellow corn which contains about 15.7 and 52.22 μg/100 g, respectively (scott and eldridge, 2005). the cp contents of the treatment diets are within the recommended values (14-19%) suggested by nrc (1994) for high producing layer hens. the me content of treatment diets were between 2820 to 2893 kcal/kg dm which were higher than the minimum values of me requirement (2700 kcal/kg dm) recommended by nrc (1994) for white leghorn layer. the calcium (2.09-2.23g) and phosphorous (0.310.37g) contents of treatment diets were near to the recommended values (2.0 gca and 0.32 gp) for white leghorn layers at first phase of laying (nrc, 1994). 4.2. feed intake and laying performance of hens there is no information in literature on feed intake, egg production, egg and chick quality, fertility and hatchability in layers fed ration containing kocho. therefore, most of the comparisons were made with other energy sources and root crops used in poultry ration as a replacement for maize. in the present experiment, 100% kocho inclusion in the ration significantly increased dm intake of white leg horn layers. in agreement with the present study, hossain et al. (2013) and ngiki et al. (2014) reported increased feed intake with increasing level of cassava root meal as a substitute for maize. however, anaeto and adighibe (2015) reported reduction in feed intake with complete replacement of maize with cassava root meal. on the other hand, similar dry matter intake was reported by ajebu et al. (2015) for hubbard broiler chickens fed 0%, 33%, 67% and 100% kocho diets and seyoum (2013) for those fed 0%, 33.3%, 66.7% and 100% furfurame, a by-product of kocho processing produced from enset, as a replacement to nigussu et al. east african journal of sciences volume 13 (1) 65-74 70 maize. the higher feed intake of layers at 100% kocho diet in the current experiment may be attributed to the composition of the diet as the lysine content was relatively high because of increased levels of soyabean in the ration (table 1). the higher hdep for layers fed on t3 and t4 in the current experiment could be due to the higher lysine content (5.5%) in kocho (mohammed et al., 2013) than maize (0.2%) (leeson and summers, 2008). the positive effect of lysine in the diet on egg production has been reported (wu, 2013). enyenihi et al. (2009) reported a higher hdep when 75% cassava tuber meal replaced the maize in the ration. inclusion of sweet potato meal up to 20% as a replacement for maize increased hdep as compared to 30% and 40% diets in white leghorn layers (afolayan et al., 2013), which could be due to the effect of anti-nutritional factors at higher levels of potato diets (ravindran, 1995). uchegbu et al. (2010) noted lower hdep when layers were fed 15% cassava root meal combined with brewery dried yeast and jack bean at dietary inclusion rates of 10 and 25%, respectively, as replacement for maize. the higher hdep at higher level of kocho in the current experiment suggests use of kocho in formulating ration for smallholder poultry as a replacement for maize during its scarcity since kocho production is available throughout the year. kana et al. (2013) found no effect on egg weight and feed conversion from pullets fed 0%, 33%, 66%, 100% cassava root meal substituted for maize while, anaeto and adighibe (2015) found decreased egg weight when birds were fed diet containing cassava root meal beyond 50% as a replacement for maize. on the other hand, aderemi et al. (2012) found that birds fed diet containing more than 25% cassava meal showed reduced feed conversion which is consistent with the current result. 4.3. egg quality characteristics egg quality characteristics were not affected by the dietary inclusion levels of kocho, except the yolk color. this implies that kocho could be used in layers ration replacing maize without compromising the egg quality characteristics. the current result is in agreement with mihret (2012) who observed similar egg quality parameters for birds fed diet containing cassava root meal replacing maize. similarly, rezaei (2006) indicated replacing rice bran with corn in layer diet had no effect on egg shell quality and haugh unit score. the reason for reduction in egg yolk color with increasing level of kocho is presumably associated with the lower beta-carotene (table 1) content of kocho. consistent to the current finding, lower yolk color was reported by kim et al. (2017) for birds fed 30% cassava tuber replacing maize. however, fafiolu et al. (2006) observed higher yolk color for layers fed malted sorghum as a substitute for maize. egg yolk color is a very important factor in consumer satisfaction and influences human appetite (amerine et al., 1995), with a preference for golden yellow to orange yolk color (hasin et al., 2006). 4.4. fertility, hatchability and chick quality the similarity of fertility among treatments justifies that kocho can replace maize without affecting fertility. etalem et al. (2013) reported lack of effect on fertility by the dietary inclusion of cassava root chips as a replacement for maize. haftu et al. (2014) also reported similar fertility for white leghorn layers fed ration containing up to 30% dietary levels of malted barley replacing maize. hatchability was reduced when kocho completely replaced maize in the diet. however, zebib (2012) observed similar effect upon substitution of maize with 0%, 25%, 50%, 75% and 100% sorghum in layers diet. ajebu et al. (2008) observed most fractions of enset to be rich in iron and manganese, but deficient in copper and zinc. the lower hatchability and higher embryonic mortality at higher level of kocho could be an attribute of insufficient availability of zinc and copper (kienholz et al., 1961; caskey et al., 1939). breeder diets that are deficient in zn can lead to a decrease in egg production, eggshell quality and hatchability. in breeder hens, zn is important component of carbonic anhydrase, which is involved in the supply of carbonate ions during eggshell formation, carboxypeptidases and dna polymerases, which are important in immune responses and hormone production (nys et al., 1999). moreover, cu is closely associated with iron metabolism and plays an important role in eggshell membrane formation, which in turn influences eggshell structure, texture, and shape (baumgartner et al., 1978). zinc and cu play important roles in embryo development as well as hatchability (kidd, 2003), and a positive relationship has been established between egg zn content and hatchability (badawy et al., 1987). thus, kocho has to be supplemented with zn and cu to enhance hatchability and minimize embryonic mortality. tona et al. (2003) reported positive correlation between eggs and chick weight. zebib (2012) also reported positive correlation of egg size and chick weight for birds fed with sorghum ration as a substitute for maize. the similarity in chick weight observed in the current result is attributed to the non significant variation in egg weight (table 4) as a result of replacing kocho for maize. this observation is in agreement with mihret (2012) who reported similar chick weight for birds fed ration containing 0%, 25%, 50%, 75%, and 100% cassava root meals as a substitute for maize. similarly, the non significant variation in chick length in the present study could be due to the comparable chick weight. chicks with better yolk utilization could have developed more body mass during the incubation period, and therefore grew longer (meijerhof, 2006). 4.5. economic evaluation in the current study 34.7, 28.4, 27.0 and 21.0 birr net return was obtained from sale of eggs on 67%, 33%, 100% and control kocho diets, respectively, within 12 weeks of experimental period. the higher net return for t3 (67%) in the current study is due to higher egg production. therefore, under the condition of the current experiment, kocho can replace maize economically up to 67%. https://www.ncbi.nlm.nih.gov/pmc/articles/pmc4377136/#cr107 nigussu et al. replacing maize with kocho in white leghorn layers ration 71 5. conclusion egg weight, egg mass and egg quality characteristics except, yolk color, were not affected by dietary levels of kocho replacing maize. yolk color and hatchability were the lowest when maize was completely substituted with kocho. hen-day egg production was higher at 67% and 100% dietary level of kocho. kocho can replace maize economically up to 67%. therefore, kocho can replace maize in layers ration when there is scarcity of maize in enset growing areas of ethiopia. however, dietary levels of kocho have to be supplemented with carotene rich ingredients to maintain normal yolk color. 6. 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and (2) select high yielding varieties through participatory variety selection approach. the research was conducted at adet and koga agricultural research sites in yilmana-densa and mecha districts (woredas), respectively. the data were collected from agronomic and farmers’ research and extension group members with involvement of fifteen (koga) and seventeen (adet) farmers of both sexes (male and female) in pair-wise and direct matrix ranking; on varieties, including necho, degu, mecha, acc.229380, padet, tadesse, debatsi, gute, wama and barieda. all collected agronomy and farmer selected criteria were analyzed. combined mean values indicated that, wama (2067 kgha-1) followed by gute (1967 kgha-1) and barieda (1717 kgha-1) were found to be high yielding finger millet varieties, and debatsie (1367 kgha-1) was identified as the least seed yielding variety. according to farmers’ evaluation criteria, over all higher rank was scored by the varieties barieda and degu followed by wama and gute varieties, in that order, with reference to ease of threshing, early maturity, high biomass yield and quality. the researcher and farmers together identified and suggested barieda, degu, wama and gute finger millet varieties for production in different ranks. among the traits preferred by farmers seed color was given priority at mecha as well as tillering capacity per mat and number of fingers per panicle at adet. early maturation was scored 146.5 and 146.8 days on wama and barieda, respectively. high tillering capacity (6.3) and (5.37) for barieda and degu shown in that order; as well as, low disease susceptibility depicted on barieda, degu and gute. the farmers also prefer white seed color for sale and injera making, and also the black seed color for local beer, arki and bread making. therefore the results indicated, farmers are interested in a wider range of traits or combinations of traits than breeders expected. keywords: combined mean values; eleusine coracana, finger millet; pair-wise and direct matrix ranking; participatory evaluation; selection criteria; variety; yield. 1. introduction in ethiopia finger millet [eleusine coracana (l.) gaertn] is one of the most important indigenous cereal crop grown largely by small holder farmers. finger millet has been mainly grown in amhara, benishangul-gumuz, oromia, southern nations, nationalities and people’s region of ethiopia, and tigray (figure 1). finger millet covers about 453,909.38 ha of land with production of 915,314.518 tons (csa, 2015). it had 3.62 and 3.39% share as compared to the national cereal crops area and production, respectively. amhara region is the largest finger millet producer, which has 53.5 and 53.56% share from national finger millet area and production, respectively. west gojam zone from amhara region has substantially a large share in area coverage with 35.21% and production 28.97% (csa, 2015). west gojam zone from amhara region has substantially a large share in area coverage with 35.21% and production 28.97% (csa, 2015). in this regard, finger millet in west gojam zone, particularly mecha district (woreda) finger milletgrowing area has equal importance as food and feed crop. in spite of the fact that the crop yield in the above zone is low as compared to other cereals (csa, 2015), its stiff straw is used for animal feed. this is because finger millet has received less priority in research and in the agricultural development extension service. similarly, several researchers reported that finger millet received less emphasis from research and development for generating improved new varieties, crop management practice and enhancement of adoption of improved technologies (andualem, 2008; degu et al., 2009; molla, 2010; altaye, 2012; tafere and melak, 2013). according to mecha district agriculture development office extension workers, (personal communication, august 10, 2013), ascribed the limitation to lack of improved finger millet varieties and other agronomic package in extension services as compared to other cereal crops. even if there are a number of released improved varieties, farmers in the study areas do not have information about the existing improved varieties. likewise, salasya et al. (2009) and osiru et al. (2010) mailto:wossen.tarekegne@yahoo.com wossen et al. east african journal of sciences volume 13 (1) 27-38 28 pointed out that if the selection and development of the varieties is performed in the absence of major stakeholders and their selection criteria, the resulting technologies would have poor and low adoption and diffusion. a similar problem was also observed in potato improved varieties for high yielding and resistance to late blight (abebe et al., 2013; gebremedhin, 2013; semagn et al., 2015). participatory variety selection addresses problems of farmers that were not touched by the formal breeding system; for instance, evaluation of released and prereleased varieties that enhance varietal diversity in farm cropping system (sangay and mahesh, 2010). likewise, thapa et al. (2009) and tiwari et al. (2009) illustrated participatory variety selection as a desirable method to resolve problems in introduction and adoption of released varieties, in evaluation and selection for preferences of farmers for their target environments. therefore, it is important to identify high yielding and good quality finger millet varieties by participating farmers of yilmana-densa and mecha districts. thus, this study was carried out with the specific objectives to (1) identify farmers’ selection criteria for finger millet genetic improvement; and (2) select high performing varieties through participatory variety selection approach. 2. materials and methods 2.1. description of experimental sites adet and koga were the testing sites found in yilmanadensa and mecha districts in west gojam zone of northwest ethiopia. their geographical and edaphic (table 1) characteristics are indicated in tabular form below. table1. description of experimental sites in the two districts of west gojam in 2013 cropping season. parameters mecha (koga) yilmanadensa (adet) soil ph 5.09-5.30 5.38-5.48 edaphic factors class clay clay soil type nitisol fluvisol % om 2.34-4.44 2.67-2.86 % total n 0.18-0.24 0.17-0.47 available p (ppm) 3.54-8.70 2.64-2.67 geographi cal positioning altitude 1960 2240 latitude 11o25'20'' 11o16'16'' longitude 37o10'20'' 37o28'38'' weather conditions maximum 28.1 26.9 minimum 9.4 10.9 rainfall (mm)/annum 1454.5 1164.1 source: wamsc, 2013; nsrc, 2006; berhanu, 2014*; nsrc, 2006**; o.morganic matter; ppm parts per million. 2.2. treatments, experimental design and agronomic management ten finger millet varieties and elite genotype necho, degu, mecha, acc.229380, padet, tadesse, debatsi, gute, wama and barieda were used for this study. the seed of each variety was obtained from adet, melkasa, pawe bako agricultural research centers, amhara region agricultural research institute (arari), oromia agricultural research institute (orari) and ethiopian institute of agricultural research (eiar). some of the major characteristics of the varieties are indicated below (table 2). table 2. description of tested finger millet varieties included in the varietal evaluation study in two districts of west gojam zone in 2013 main cropping season. no. variety year of release origin seed color maintainer 1 necho 2011 local white adarc/arari 2 degu 2005 local black adarc/arari 3 mecha 2014 local red brown adarc/arari 4 acc 229380 local brown adarc/arari 5 padet 1998/99 introduced brown marc/eiar 6 tadesse 1998/99 introduced brown marc/eiar 7 debatsi 2010 local brown parc/eiar 8 gute 2009 local brown barc/oari 9 wama 2007 introduced brown barc/oari 10 barieda 2009 local brown barc/oari note: adarc-adet agricultural research center; arari -amhara region agricultural research institute: marc-melkasa agricultural research center; eiar-ethiopian institute of agricultural research; parc-pawe agricultural research center; barcbako agricultural research center; oari-oromia agricultural research institute wossen et al. finger millet [ eleusine coracana (l.) gaertn] varieties evaluation 29 figure 1. map of ethiopia indicating the study areas for the field experiment in 2013 and major finger milletproducing regions of ethiopia. each experimental plot had an area of 10 m2 with five rows of 2 m length spaced at 0.40 m between rows and 0.15 m between plants as well with seed rate of 15 kgha1. the ten finger millet varieties were laid down in a randomized complete block design (rcbd) with three replications. fertilizer rates of 100/50 kgha-1 for dap and urea were applied in rows, respectively. sowing was done on july 3 and july 11, 2013 at adet and koga experimental sites, respectively. at the same time the guard rows were planted at both end side of experimental area. the total required amount of phosphorous applied at basal, but from the total nitrogen applied half was used at planting and the remaining was top dressed at tillering stage. hand hoeing and weeding was made one and two times, respectively over the growing season to put the experimental plots free of weeds. there was no major insect pest incidence in the season and hence plants were not sprayed with any agro-pesticide. other agronomic management practices were done as per their recommendation. depending on the maturity period of each variety, harvesting was done, from mid up to last week of december, 2013. threshing was done after the harvest was exposed to sun drying. 2.3. agronomic data collected the phenological, seed yield and yield components and blast susceptibility and lodging percentage of the crop are recorded as follows. days to flowering (dtf): this parameter was recorded as number of days from sowing to stage when ears emerged from 50% of the tillers per plot. days to physiological maturity (dpm): it was recorded as number of days from sowing to stage when 50% of the tillers per plot had matured ears (detected by yellowing of leaves). plant height (ph) (cm): it was recorded by measuring the height of plants from ground level to the tip of inflorescence (ear), at dough stage. number of tillers per plant (not): the number of tillers per plant was number of basal tillers that bear mature ears and recorded from five randomly taken plants of each plot at harvest. number of ears per plant (noe): the number of ears per plant was recorded as the total number of ears produced from all tillers and recorded from five randomly taken plants of each plot at harvest. number of fingers per ear (nof): the number of fingers per ear was recorded from five randomly taken plants at harvest. finger length (fl) (cm): the finger length was recorded from the base of the ear to the tip of the finger at each five randomly taken plants of main tillers, at dough stage. biomass yield/plot (bmy) (kg): the biomass yield was recorded from weight of the aboveground parts (stem + leaves + seed) by sensitive balance at harvest after sun drying. seed yield (syd) (kg ha-1): seed yield was determined by harvesting all plants from the five rows of each plot, since there was no space between plots to remove the border effect. seeds were weighed by sensitive balance and approximately adjusted to 10% moisture content by drying in the sun. thousand seed weight (tsw) (g): thousand seeds were counted manually from a bulk of threshed seeds of each plot, their moisture were adjusted and weighed in the same way as seed yield data. harvest index/plot (hi) (%): harvest index was estimated from the proportion of seed weight to the above-ground biomass weight at harvesting dry weight (stem + leaves + seed) at harvest×100. head blast: it was recorded and scored on a 1-9 scale, where: 1 = no lesion (resistant/no susceptibility); 3 = low susceptibility, 5 = medium susceptibility, 7= high susceptibility. lodging susceptibility: this parameter was recorded at the stage of maturity as 1 = very low or no lodging, 3 = low lodging, 5 = intermediate and 7 = high lodging susceptibility according to the finger millet descriptors (ibpgr, 1985). 2.4. farmers’ participatory variety selection the selected research areas for finger millet research through participatory variety selection (pvs) are found within the research mandate area of adet agricultural research center (aarc). during 2004, adet agricultural research center formally adopted clientwossen et al. east african journal of sciences volume 13 (1) 27-38 30 oriented research for enhancing the technology generation and transfer processes through establishment and working with farmers research and extension group (freg). the farmers’ research and extension group members were selected by dwellers of the peasant association and the established size of farmers’ research and extension group ranged from 15 to 45 farmers based primarily on their finger millet indigenous knowledge, capable for technology transfer and willingness to participate in the research. the farmers’ research and extension group members of fifteen (koga) and seventeen (adet) farmers of both sexes (male and female) participated from each district in the evaluation and selection of improved finger millet varieties. to undertake participatory variety selection, farmers identified the selection criteria with respective weight on the basis of their interest. then the varieties were ranked accordingly. decision was made among farmers research and extension group members through group discussion on the appropriate growth stage for evaluation. the farmers then observed and evaluated the varieties based on their overall performance at physiological maturity stage. the farmers’ research and extension group members were regrouped by mixing literate and illiterate members to facilitate for writing the criteria and varieties in order. discussions were made in each group and ranked the criteria using pair-wise ranking matrix and obtained the relative weight of each character by considering their interest. lelo et al. (1995) stated that selection criteria identified by farmers were ranked depending on the number of repetition of each selection criterion chosen by the respective group. after identifying the weight, randomly taken one block of the experimental site, farmers obtained clarification how to evaluate ten varieties of finger millet based on the fitness of specific agreed selection criteria. scores were given to each variety based on the selection criteria (1 = very good, 2 = good, 3 = average, 4 = poor and 5 = very poor) and ranked each of them. to select the best variety fitted to farmers’ interest, multiple weights were given to each criterion by the rank of the varieties. according to de boef and thijssen (2006) scoring and ranking were done based on agreement of farmers involved during discussion on the criteria and variety selection. 2.5. data analysis analysis of variance (anova) was done for all the traits following procedures of gomez and gomez (1984) using statistical analysis system (sas, 2002). combined data analysis was done on the measured parameters in the two districts, since the error variances were homogenous. the mean separation was done with duncan’s multiple range test (dmrt) method. data collected through participation of farmers’ research and extension group members were analyzed using pairwise ranking and direct matrix procedure. the criteria were fixed in the first row while the varieties in the first column of the table; and ranking was done in groups. 3. results and discussion 3.1. performance of tested finger millet varieties in two locations the analysis of variance (anova) revealed significant (p≤0.01) difference among the varieties for phenological and agronomic traits, and indicated the presence of sufficient variability, which could be attributed to the genetic potential of the varieties used among the evaluated varieties and for the traits under consideration (table 3). this result is in agreement with similar findings of sorghum (yalemtesfa et al., 2014; mihret, 2015). results of combined analysis for days to flowering ranged from 96.5 to 110.3 days. except debatsie, other tested finger millet varieties flowered earlier, but the least range was recorded for acc.229380 (table 3). days to physiological maturity ranged from146.5 to 158.3 days. the finger millet varieties wama and barieda matured earlier than the rest varieties and recorded 146.5 and 146.8 days, respectively, but debatsie matured later (158.3 days) (table 3). the physiological maturity for the varieties wama and degu agreed with that of the observation by molla (2012). the finger millet degu was the tallest (mean height 73.67 cm) variety, while debatsie was the shortest (with mean height of 56.1 cm) variety in the group (table 3). as far as finger length is concerned, degu had the longest (mean of 11.67 cm), followed by necho (11.2 cm) and barieda (9.5 cm); however, the varieties tadesse and padet (6.07 cm) and debatsie (5.5 cm) had the shortest lengths (table 3). high number of fingers (8.2 fingers per panicle) was recorded for the variety necho, followed by the variety degu (7.23) and debatsie (7.17), whereas less numbers of 4.6 and 5.0 were recorded for the varieties wama and mecha, respectively, than the rest varieties. high mean numbers of tillers of 6.3, 5.37 and 4.5 were recorded for the varieties barieda, degu and necho, in that order. correspondingly, less numbers of fingers of 3.5 and 3.53 were recorded for the acc. 229380 and for both varieties tadesse and gute. high number of ears was recorded for the variety degu (7.63), followed by barieda (6.7) and necho (5.7); but less numbers of 4.0 and 4.03 were recorded for the acc.229380 and tadesse, respectively. previously molla (2012) reported similar results with the current findings with reference to plant height, finger length and number of fingers tested under various environments. the varieties evaluated in the present study had a wide adaptation across the various agro-ecologies of the study areas. the differences in plant heights, finger lengths, numbers of fingers, numbers of tillers and numbers of ears among the finger millet varieties might be due to inherent characters of the varieties and the variability in the rainfall distribution in the study areas. finger length per plant, number of fingers per plant, number of tillers wossen et al. finger millet [ eleusine coracana (l.) gaertn] varieties evaluation 31 per plant and number of ears per plant are important features of the crop in determining the yield potential, particularly for varieties having thin straws (stems); however, this result contradicts with the tested finger millet performance that illustrated maximum yield with stiff stalks (i.e. wama and gute varieties). wama and gute varieties showed higher seed weight and wider finger width with large number of seeds per finger. the present research results are consistent with the investigation by molla (2012). table 3. combined mean values for different traits of tested finger millet varieties in two districts of west gojam zone in 2013 main cropping season. no. varieties days to flowering days to maturity plant height finger length number offinger number of tiller number of ear 1 necho 99.00b 150.80b 70.85abc 11.20a 8.20a 4.60bc 5.70bc 2 degu 100.50b 149.00bc 73.67a 11.67a 7.23b 5.37ab 7.63a 3 mecha 99.30b 148.80bc 65.50bc 8.03c 5.00cd 4.37bc 5.10cd 4 ac.229380 96.50b 147.30bc 64.70c 7.50c 5.50cd 3.50c 4.00d 5 padet 99.20b 148.30bc 68.70abc 6.07d 5.07cd 3.60c 4.10d 6 tadesse 98.70b 148.50bc 69.47abc 6.07d 5.63c 3.53c 4.03d 7 debatsi 110.30a 158.30a 56.10d 5.50d 7.17b 3.73c 4.10d 8 gute 99.30b 148.20bc 73.17a 7.62c 5.07cd 3.53c 4.10d 9 wama 99.00b 146.50c 71.63ab 7.97c 4.60d 3.67c 4.20d 10 barieda 101.30b 146.80c 67.10abc 9.50b 5.27cd 6.30a 6.70ab mean 100.32 149.27 68.52 8.11 5.88 4.22 4.97 se (+) 0.54 0.74 0.95 0.124 0.11 0.1 0.14 cv (%) 1.32 1.22 3.42 3.75 4.62 5.91 6.99 the analysis of variance (anova) revealed highly significant (p≤0.01) difference between locations for phenological and agronomic traits between locations (table 4). a result of combined analysis for flowering was early (97.8 days) at mecha, while it was late (102.83 days) at adet (table 4). short duration (147.67 days) was required for physiological maturity at mecha. on the contrary, plants required long duration (150.87 days) to mature at adet (table 4). differences among varieties for phenological traits could be due to the inherent genetic ability of the varieties, altitude and climate differences. hence, the longest duration (days) to physiological maturity was suitable to areas having long production season, but the early maturing ones are suited to short crop production season. table 4. combined mean values for phenological and agronomic traits of finger millet tested varieties across locations in west gojam zone in 2013 main cropping season. no. location days to 50% flowering days to physiologic al maturity plant height (cm) finger length (cm) number of fingers number of tillers per mat number of ears per panicle 1 adet 102.83a 150.87a 64.85b 8.28a 6.42a 4.71a 5.90a 2 mecha 97.80b 147.67b 71.34a 7.95b 5.33b 3.727b 4.04b mean 100.3 149.27 68.1 8.11 5.88 4.22 4.97 se(+) 0.24 0.33 0.43 0.06 0.05 0.05 0.06 cv (%) 1.32 1.22 3.42 3.75 4.62 5.91 6.99 3.2. combined analysis of yield and yield components of tested finger millet varieties the analysis of variance (anova) revealed significant (p ≤ 0.01) difference in yield and yield components among the tested finger millet varieties except for biomass yield. the mean seed yield of the varieties ranged from 1,367 to 2,067 kg ha-1 for debatsie and wama, respectively. the high yielding varieties were wama (2,067 kg ha-1), gute (1,967 kg ha-1) and barieda (1,717 kg ha-1). on the contrary, debatsie (1,367 kg ha1), acc.229380 (1,383 kg ha-1) and necho (1,417 kg ha1) were low yielding varieties (table 5). highly significant seed yield variations among varieties could be due to inherent genetic characters of the varieties, different and uneven rainfall distribution and variation in altitudes. high value (3.33 g) of thousand seed weight was recorded for the varieties wama and mecha, which had large seed sizes. but, barieda, degu and necho had the respective low values of 2, 2.13 and 2.18 g thousand seed weight (table 5). in agreement with the present finding previously several researchers reported similar results in their investigations and stated the presence of significant difference among varieties in seed yield of wossen et al. east african journal of sciences volume 13 (1) 27-38 32 finger millet (andualem, 2008; chrispus, 2008; molla, 2012). the variety wama had the highest performance in seed yield and biomass yield both in this and previous study of molla (2012). the variation for seed yield and thousand seed weight among varieties might be due to the inherent genetic difference of the tested finger millet varieties. combined mean values of seed yields and harvest indices of debatsie, padet and tadesse were less than that of the other tested finger millet varieties even though they had better performance in biomass. the varieties wama, gute and barieda showed consistent performance in seed yield, biomass yield and harvest indices in both tested areas, which, in turn, contributed to their selection preferences by farmers and plant breeders. the breeders showed that the higher yielding varieties were found to have both higher biomass and harvest indices than the low yielder varieties. therefore, wama, gute and barieda had genetic differences in more than one preferred character, namely seed yield, harvest index and biomass yield, could use as parent material in breeding program to improve finger millet. the analysis of variance (anova) revealed highly significant (p≤0.01) difference in yield and yield components between locations except for thousand seed weight and harvest index (table 6), indicating the presence of sufficient genotypic differences in finger millet for the traits under consideration. the variability among the evaluated traits could be attributed to the genetic potential of the varieties used, which is in concurrence with the results of sorghum (yalemtesfa et al., 2014; mihret, 2015). about 1693 kg ha-1 seed yield was obtained at adet as compared to 1473 kg ha-1 at mecha (table 6). generally, the performance of tested finger millet varieties was recorded higher at adet than at mecha. this might be because of occurrence of favorable weather conditions throughout the growing season of the crop at adet. table 5. combined mean values for yield and yield components of tested finger millet varieties in two districts of west gojam zone in 2013 main cropping season. no. varieties seed yield (kg ha-1) 1000 seed weight (g) biomass yield(kg ha-1) harvest index (%) 1 necho 1417c 2.18e 7300b-d 19.69a-c 2 degu 1483bc 2.13e 7900a-d 19.03b-d 3 mecha 1450c 3.33a 6800cd 22.03ab 4 ac.229380 1383c 2.77cd 6600d 21.12ab 5 padet 1483bc 2.95bc 9550a 15.63cd 6 tadesse 1500bc 3.03bc 9167ab 16.57cd 7 debatsi 1367c 2.53d 9100ab 15.18d 8 gute 1967a 3.17ab 8800a-c 22.88ab 9 wama 2067a 3.33a 9067ab 23.83a 10 barieda 1717b 2.00e 7783a-d 22.71ab mean 1583 2.74 8.21 19.87 se (+) 0.0396 0.09 0.41 1.2 cv (%) 6.125 7.55 12.3 14.84 3.3. lodging susceptibility and reaction of the tested finger millet varieties to disease lodging susceptibility among varieties of finger millet and across the two locations observed was none except the variety degu with low lodging susceptibility (table 7). equal to the other parameters, disease resistant varieties are more advantageous for finger millet improvement. among tested finger millet varieties, susceptibility difference for head blast disease was expressed at both research locations. this might have occurred due to genetic variation in the finger millet varieties and dissimilarity in weather conditions and altitudes of the research areas. the environmental conditions, such as low minimum up to high maximum temperatures and high rainfall and low altitude were recorded at mecha. in connection to this, head blast disease was more severe in mecha than in adet. similarly, patro and madhuri (2014) expressed that the increase in temperature high rainfall and high relative humidity would increase infection on susceptible finger millet varieties by head blast disease. the values of reaction of tested finger millet varieties to head blast disease at adet and mecha are tabulated (table 7). the occurrence of the disease varied among varieties and across locations. the severity of head blast was relatively much higher on necho, degu, mecha, padet, gute and wama in mecha than in adet district. but, barieda and debatsie showed resistant reaction, while tadesse and acc.229380 exhibited moderately susceptible reaction to head blast. according to lule et al. (2013), an average of 42% finger millet grain yield was lost due to blast disease in ethiopia. similarly, finger millet yield loss was estimated at 41.8% (gashaw et al., 2014). wossen et al. finger millet [ eleusine coracana (l.) gaertn] varieties evaluation 33 table 6. combined mean values for yield and yield components of the varieties across locations in west gojam zone in 2013 main cropping season. n o . l o c at io n (d is tr ic t) s e ed y ie ld (k g h a1 ) 1 0 0 0 s ee d w e ig h t (g ) b io m as s y ie ld (k g h a1 ) h ar v e st in d e x ( % ) 1 adet 1693a 2.79a 9056a 19.08b 2 mecha 1473b 2.69b 7356b 20.65a mean 1583 2.74 8207 19.87 se(+) 0.02 0.04 0.18 0.54 cv (%) 6.13 7.55 12.3 14.84 table 7. mean values of tested finger millet varieties for disease reaction and lodging susceptibility at two locations in west gojam zone in 2013 main cropping season. head blast lodging no. varieties mecha adet mecha adet 1 necho 3 1 1 1 2 degu 2 1 1 1.33 3 mecha 3 1 1 1 4 acc.229380 5 1 1 1 5 padet 4 1 1 1 6 tadesse 5 2 1 1 7 debatsie 1 1 1 1 8 gute 3 1 1 1 9 wama 4 2 1 1 10 barieda 1 1 1 1 head blast: 3= low susceptibility, 5= medium susceptibility, 7= high susceptibility. lodging: 1= very low or no lodging, 3= low lodging, 5= intermediate and 7= high lodging susceptibility. 3.4. farmers’ evaluation results of tested finger millet varieties the evaluation result of farmers’ research and extension group members’ selection criteria are described here under table 8 and table 9. the selection criteria that farmers depended on for evaluation were seed yield, yield components, seed color and disease resistance; which are similar to selection criteria identified for bean (asrat and fitsum, 2008; mekonen et al., 2012) and sorghum (yalemtesfa et al., 2014). at the time of criteria selection, women and men farmers were grouped separately; and women farmers chose seed yield and seed color (especially at adet) traits, while men focused on seed yield and other yield related characters. the interest of selection depends on the demand to generate income in local market and home consumption in women’s and needs for food and feed for animals in men. focus group discussion (fgd) was under taken together in the farmers’ research and extension group members prior to individual group’s variety selection to depict the performance of variety according to the selection criteria in each experimental plot (figure 2). figure 2. freg members holding focus group discussion (fgd) for identification of stage of evaluation, and setting selection criteria for evaluation of performance of finger millet varieties in two districts of west gojam zone in 2013 main cropping season table 8. pair-wise ranking matrix of freg selection criteria at mecha site, (n=15), west gojam zone in 2013 main cropping season. n o. criteria early maturity biomass quality seed yield disease resistance biomass yield seed color total ran k 1 early maturity x early maturity seed yield disease resistance early maturity seed color 2 4 2 biomass quality x seed yield disease resistance biomass yield seed color 0 6 3 seed yield x seed yield seed yield seed yield 5 1 4 disease resistance x disease resistance disease resistance 4 2 5 biomass yield x seed color 1 5 6 seed color x 3 3 note: number of participants=15 (male=12, female=3) wossen et al. east african journal of sciences volume 13 (1) 27-38 34 table 9. pair-wise ranking matrix of freg selection criteria at adet site, (n= 17) west gojam zone in 2013 main cropping season. no. criteria early maturity biomass quality seed yield disease resistance tiller capacity number of finger total rank 1 early maturity x early maturity seed yield disease resistance tiller capacity early mature 2 4 2 biomass quality x seed yield disease resistance tiller capacity number of finger 0 6 3 seed yield x seed yield seed yield seed yield 5 1 4 disease resistance x disease resistance disease resistance 4 2 5 tiller capacity x tiller capacity 3 3 6 number of finger x 1 5 note: number of participants=17 (male= 15, female= 2) farmers’ research and extension group members found in both sites were evaluated general performance of varieties based on the selection criteria (table 10 and table 11). table 10. focus group discussion and evaluation of merits and drawbacks given for each finger millet variety at mecha, west gojam zone, during 2013 cropping season. no. variety merits drawbacks 1 necho long finger length, good grain filling, preferred for injera uniformity problem, susceptible to blast disease 2 degu long finger length, high tiller, ease of threshing, high biomass yield and quality, tall height uniformity problem 3 mecha long finger length, tall height, good grain filling, average biomass quality low uniformity 4 acc.229380 average finger length, good biomass yield and quality non effective tiller, low uniformity, susceptible to disease 5 padet _ short finger length, low tillering capacity, poor biomass quality 6 debatsi _ late maturing, short height, short finger length, non effective tiller 7 gute tall height, long finger length, good grain filling, high biomass yield, average biomass quality low tillering capacity 8 wama good grain filling, wide finger width, average biomass quality short finger length, low tillering capacity 9 barieda good performance, tall height, long finger length, high tillering capacity, have uniformity, ease of treshing, high biomass yield and quality _ 10 tadesse _ short finger length, low tillering capacity, low uniformity, low biomass quality each group of freg members’ ranked each variety based on the agreed selection criteria and the total points each scored and the ranks of finger millet varieties were depicted (table 12 and 13). the degree of concurrence between the results of focus group discussion (table 10 and 11), and the information gathered during participatory variety selection in individual group evaluation were high (table 12 and 13). the process of ranking revealed that there were differences among finger millet varieties. high scores were given to five of the finger millet varieties, including barieda, degu, gute, wama and acc. 229380 at mecha (table 12). similarly, the finger millet varieties barieda, degu, necho, wama and gute scored one up to five, in that order, at adet (table 13). wossen et al. finger millet [ eleusine coracana (l.) gaertn] varieties evaluation 35 table 11. focus group discussion and evaluation of merits and drawbacks given for each variety at adet, west gojam zone, during 2013 cropping season. no. variety merits drawbacks 1 necho tall height, long finger length, have branched tillers, medium biomass yield and quality low uniformity, low basal tillering capacity 2 degu high basal tillering capacity, ease of threshing, high biomass yield and quality low finger thickness, low branched tillers 3 mecha _ short finger length, low tillering capacity, 4 acc.229380 _ short finger length, low tillering capacity, low number of finger, 5 padet wide finger width, good grain filling low number of fingers, low biomass yield and quality 6 debatsi more number of finger, good grain filling short height, low biomass quality 7 gute long finger length, good grain filling, medium biomass yield and quality low number of fingers 8 wama good grain filling, high tillering capacity, medium biomass quality, high biomass yield _ 9 barieda long finger length, more number of finger, high uniformity, high tillering capacity, ease of trashing high biomass yield and quality _ 10 tadesse good grain filling low tillering capacity, low biomass quality table 1. direct matrix ranking finger millet varieties for the selected traits by freg at mecha west gojam zone, in 2013 cropping season. no. selection criteria relative weight finger millet varieties necho degu mecha a2293 80 padet debat si gute wama baried a tadess e 1 early maturity 4 (4.7) 18.8 (3) 12 (3) 12 (3.3) 13.2 (2.7) 10.8 (4.3) 17.2 (2) 8 (1.7) 6.8 (1) 4 (3.7) 14.8 2 biomass quality 6 (4.7) 28.2 (1) 6 (4) 24 (2.3) 13.8 (3.3) 19.8 (5) 30 (2) 12 (2.7) 16.2 (1) 6 (4) 24 3 seed yield 1 (4.7) 4.7 (2.7) 2.7 (2.7) 2.7 (3.7) 3.7 (3) 3 (5) 5 (1) 1 (2) 2 (1) 1 (4.3) 4.3 4 disease resistance 2 (1.7) 3.4 (1) 2 (1.3) 2.6 (1.7) 3.4 (1.3) 2.6 (1.7) 3.4 (1.3) 2.6 (1.3) 2.6 (1) 2 (1.7) 3.4 5 biomass yield 5 (4.3) 21.5 (1) 5 (2.3) 11.5 (3) 15 (4.3) 21.5 (3) 15 (3.3) 16.5 (3.3) 16.5 (1) 5 (4) 20 6 seed color 3 (1) 3 (2) 6 (3) 9 (3) 9 (3) 9 (4) 12 (3) 9 (3) 9 (4) 12 (3) 9 total 21 79.6 33.7 61.8 58.1 66.7 82.6 49.1 53.1 30 75.5 rank 9 2 6 5 7 10 3 4 1 8 note: numbers in parenthesis are mean scores given by farmers to each variety with respect to each character (5=very poor, 4=poor, 3=average, 2=good, 1=very good); numbers in bold case are the product of relative weight of the selection criterion and the score of a variety given by farmers. ranks are in ascending order from one to ten. 3.5. identified finger millet varieties for yilmanadensa (adet) and mecha districts’ tested finger millet varieties suitable to both study areas were identified based on their seed yield potential and farmers’ preferences. the overall selection results are presented in the following sections. varietal yield performance and farmers’ variety evaluation ranks are presented illustrated and tabulated, respectively (figure 3, table 14). the traits utilized as selection criteria for the tested finger millet varieties are in harmony with previous finger millet research findings (molla, 2012) and most of the selection criteria at physiological maturity used were similar to sorghum varietal selection criteria (yalemtesfa et al., 2014). accordingly, the present study on finger millet selection criteria and ranks were presented by farmers listed on the bases of their order of preferences. hence, farmers’ interest of traits and their order of importance could be explained through participatory research beyond the expectation of plant breeders (ceccarelli and grando, 2006; fekadu, 2013). generally, participatory variety selection was effective and reliable for identifying appropriate varieties through partnership with resourcepoor farmers (tafere et al., 2012). wossen et al. east african journal of sciences volume 13 (1) 27-38 36 table 13 direct matrix ranking of finger millet varieties for the selected traits by freg of adet west gojam zone, in 2013 cropping season. finger millet varieties no. selection criteria relative weight necho degu mecha a.229380 padet debatsi gute wama barida tadesse 1 early maturity 4 (2.7) 10.8 (1) 4 (4) 16 (3.7) 14.8 (2.7) 10.8 (5) 20 (4.3) 17.2 (2.3) 9.2 (1) 4 (3.3) 13.2 2 biomass quality 6 (2) 12 (1) 6 (2.7) 16.2 (3.7) 22.2 (3.7) 22.2 (5) 30 (1.7) 10.2 (2) 12 (1) 6 (4.7) 28.2 3 seed yield 1 (2) 2 (2) 2 (3.7) 3.7 (2.7) 2.7 (2.7) 2.7 (5) 5 (1.7) 1.7 (1) 1 (1) 1 (3) 3 4 disease resistance 2 (1) 2 (1.3) 2.6 (1.7) 3.4 (1.7) 3.4 (1.3) 2.6 (1.3) 2.6 (1.7) 3.4 (1.3) 2.6 (2) 4 (2.3) 4.6 5 tiller capacity 3 (2) 6 (1) 3 (3) 9 (3) 9 (3.7) 11.1 (5) 15 (3.3) 9.9 (2.7) 8.1 (1) 3 (3.7) 11.1 6 number of finger 5 (1) 5 (2.7) 13.5 (3) 15 (3.3) 16.5 (3.7) 18.5 (5) 25 (3.7) 18.5 (2.3) 11.5 (2) 10 (2.7) 13.5 total 37.8 31.1 63.3 68.6 67.9 97.6 60.9 44.4 28 73.6 rank 3 2 6 8 7 10 5 4 1 9 note: numbers in parenthesis are mean scores given by farmers to each variety with respect to each character (5=very poor, 4=poor, 3=average, 2=good, 1=very good); numbers in bold case are the product of relative weight of the selection criterion and the score of a variety given by farmers. ranks are in ascending order from one to ten. the result of seed yield performance of ten finger millet varieties in both research areas, namely mecha and adet (figure 3) revealed that wama, gute and barieda produced higher (mean 1583 kg ha-1) seed yield than the means for the rest tested finger millet varieties. similarly, wama, gute and barieda, except all the tested varieties, produced above the average (1661 kg ha-1) seed yield of finger millet in west gojam zone (csa, 2015). table 2. farmers’ preference ranking of tested finger millet varieties at two locations (mecha and adet) in west gojam zone in 2013 main cropping season. no. finger millet varieties mecha adet overall ranking 1 necho 9 3 6 2 degu 2 2 2 3 mecha 6 6 6 4 acc.229380 5 8 7 5 padet 7 7 7 6 tadesse 8 9 9 7 debatsie 10 10 10 8 gute 3 5 3 9 wama 4 4 3 10 barieda 1 1 1 the overall ranks of the tested finger millet varieties (table 14) were evaluated by farmers research and extension group members of the farmers’ associations in adet and koga research sites in west gojam zone. farmers’ preference ranking indicated that barieda, degu, wama and gute ranked one up to four, respectively, in that order. the identified finger millet varieties based on yield potential and farmers’ preferences are the same, but, their harmony differs only because of selected varieties prioritization order. this occurred due to the need for multiple traits found in one variety, like straw palatability, early maturity and seed color. figure 3. seed yield performance of finger millet varieties in two location of west gojam zone in 2013 main cropping season. 4. conclusion the results of the study showed that the tested finger millet varieties had a wide agro-ecological adaptation. the identified varieties by the farmers based on yield potential and other agronomic parameters in both study areas’ were the same, but, their concurrence differed only in priotization order of varieties. this is because the farmers’ research and extension groups’ interaction in participatory variety selection indicated differences by farmers in their choice of finger millet varieties based on wossen et al. finger millet [ eleusine coracana (l.) gaertn] varieties evaluation 37 their preferred traits and evaluating the performance of better varieties. these showed that, the developed participatory finger millet variety selection criteria could identify suitable varieties with necessity of more than one criteria preferred by farmers, and, this farmers’ evaluation helps to introduction, adoption and dissemination of selected improved varieties and different farmers in different communities select different varieties therefore the biodiversity over the total area is maintained or even increased in the tested areas along with local landraces grown by farmers. in this regard, the underlying rationale and empirical evidence presented in the text argue strongly for success of this approach. therefore the research should give priority for a wider range of traits or combinations of traits as farmers’ interest. 5. acknowledgements this paper is part of phd research work done at haramaya university. the authors thank the ministry of education and debre markos university for their financial support. furthermore, we are grateful to amhara agricultural research institute (arari) and adet agricultural research center (aarc), particularly finger millet research team for access to the internet, material and place of 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mekonen haile, firew mekbib and habtamu zeleke. 2012. performance and farmers’ evaluation of released common bean varieties in dawro zone, southwestern ethiopia. journal of crop improvement, 26: 197-210. mihret yirgu. 2015. genetic gain in lowland sorghum [sorghum bicolor (l.) moench] varieties in ethiopia. international journal of horticulture and plant breeding sciences, 2(1): 1 -13 molla fentie. 2010. genotype x environment interaction and stability analyses of yield and yield related traits of finger millet (eleusine coracana (l) gaertn) varieties in northwestern ethiopia. m.sc thesis, haramaya university, haramaya, ethiopia. molla fentie. 2012. participatory evaluation and selection of improved finger millet varieties in northwestern ethiopia. international research journal of plant science, 3: 141-146. nsrc (national soil research center). 2006. soils of adet agricultural research center testing sites. addis abeba, ethiopia. osiru, d.s.o., balyejusa-kizito, e., bisikwa, j., 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t.p., virk, d.s. and sinclair, f.l. 2009. rapid gains in yield and adoption of new maize varieties for complex hillside environments through farmer participation. improving options through participatory varietal selection (pvs). field crops research, 111: 137-143. wamsc (western amhara meteorological services center). 2013. seasonal agrometeorological data. bahir dar, ethiopia. yalemtesfa firew, firew mekbib and asfaw adugna. 2014. performance and farmers’ evaluation of released sorghum [sorghum bicolor (l.) moenech) varieties in benishangul-gumuz region of ethiopia. msc thesis: haramaya university, haramaya, ethiopia. east african journal of sciences (2019) volume 13 (1) 39-50 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: chemeda2012@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) heterosis in sesame (sesamum indicum l.) hybrids of diverse parental lines for agromorphology characters in ethiopia chemeda daba1, amsalu ayana2, adugna wakjira,3 and habtamu zeleke2 1bako agricultural research center, p. o. box 03, bako, west shewa, ethiopia 2haramaya university, p. o. box 138, dire dawa, ethiopia 3ethiopian institute of agricultural research, p. o. box 2003, addis ababa, ethiopia abstract: heterosis breeding is a technique with potential to improve sesame yield. the productivity of sesame need to be increased significantly to exploit the maximum benefit from the increasing world market demand for this crop as well as to reduce the deficit in edible oil in ethiopia. the objective of this study was to determine the extent of heterosis for yield and yield related traits in sesame. the present investigation on sesame comprised a full-diallel set of 10 parents and their 90 f1 crosses. the hybrids were produced during the main growing season of 2011. seeds of all f1 and their parents were planted in randomized complete block design, with three replications at two experimental sites viz., uke (1383 meters above sea level) and wama (1436 meters above sea level) of bako agricultural research center on 12 and 14 june 2012, respectively. the data was recorded for four traits viz., days to flowering, branches per plant, yield per plan (g) and oil content (%). analysis of variance computed for each location and over locations revealed highly significant differences among the parental lines and f1 hybrids for all the studied traits. the magnitude of mid and better parent heterosis for seed yield ranged from -40.0 to 31.6-% and40.2 to 23.3%, respectively. the range of standard heterosis for yield and oil content was -41.8 to 13.6% and –5.6 to 7.8%, respectively. seven crosses of f1 and reciprocal f1 displayed positive and significant standard heterosis for number of branches per plant while a total of 35 (37.6%) crosses of f1and reciprocal f1 had negative better parent heterosis for days to flowering of which 18 (20.0%) displayed negative and significant standard heterosis. a total of 16 crosses (of f1 and reciprocal f1) displayed positive better parent heterosis for seed yield per plant, of which bg006 x ew003-1, ew023-2 x dicho and bg006 x ew002 crosses of f1and rcecprocal f1 exhibited positive and significant standard heterosis of 10.5, 29.4 and 13.6%, respectively. all except two crosses of f1 displayed positive standard heterosis for seeds oil content of which 74 (82.22%) of crosses exhibited positive and significant standard heterosis. the different magnitude of heterosis displayed by some crosses of f1 and their reciprocal f1 for all characters indicated the presence of maternal inheritance, which suggested the importance of considering the use of female parents in the respective crosses and characters to maximize the exploitable heterosis in hybrids. generally, the results of the research revealed higher chances of producing heterotic sesame hybrids that combined the highest yield, oil content, early maturity and high number of fertile branches. this suggests that heterosis breeding and/or hybridization could be one of the breeding methods in sesame in ethiopia to produce heterotic hybrids that combine desirable traits as many as possible or to develop potential recombinant pure lines from segregating generations. keywords: better parent heterosis, mid parent heterosis, oil content, seed yield and standard heterosis. 1. introduction sesame (sesamum indicum l.) is a source of edible oil with high nutritive value and keeping quality (pathak et al., 2014). it is the most important oil crop grown in ethiopia having tremendous potential for export; making ethiopia the second largest world exporter of raw sesame seed after india (rutes et al., 2015). however, domestic processing of edible oil from sesame seed in ethiopia is low.therefore, ethiopia imports large quantities of edible oil, mainly palm oil (wijnands et al., 2011), to satisfy the demand of increasing human population. the production and productivity of sesame need to be increased significantly to exploit the maximum benefit from the increasing world market demand for sesame as well as to reduce the deficit in edible oil in ethiopia. since 1960s, efforts have been made to improve the productivity of sesame through introduction, which have high yielding, high oil quality and disease esistant/tolerant varieties in ethiopia (tadele, 2005). studies on genetic gain progress in sesame variety showed the existence of reasonable level of yield and oil quality over the last five decades (musa et al., 2011) which is advanced nearly to 1 ton ha-1. however, its productivity is still low (0.8 ton ha-1) (csa, 2017) as compared its genetic potential, which is 2 ton ha-1. therefore, it is vatal to develop high yielding varieties with high oil quality and disease resistance than the released varieties, which are under production. heterosis breeding is the most important breeding method in both self and cross-pollinated crops to develop improved varieties. parental identification and evaluation is the major technique in the development of crop varieties in which to enhance productivity (gowda et al., 2010). estimation of heterosis provides clues to select desirable parents for future crossing in hybridization. heterosis has been developing due to deviation from the parental means, which is expressed chemeda et al. east african journal of sciences volume 13 (1) 39-50 40 in increase vigourity and productivity (khan et al., 2009). heterosis breeding is a potential technique to improve yields in sesame (nayak et al., 2017). sesame, although predominantly a self-pollinated crop, its reproductive biology and making crosses offers a good scope for exploitation of heterosis (rani et al., 2015). high levels of mid parent heterosis in sesame have been reported from various countries (sundari and kamala, 2012). in addition, the heterotic response over the standard check (jadhav and mohrir,2013;, vavdiya et al.,2013; rani et al.,2015) and over better parent (heterobeltiosis) for seed yield and yield components has been observed in sesame (prajapati et al., 2010; padmasundari and kamala,2012;chaudhari et al., 2017). heterosis over better parent is relatively more important than the mid heterosis for commercial exploitation of hybrids (prajapati et al.,2010, padmasundari and kamala 2012; tripathy et al.,2016; nayak et al.,2017). the magnitude of heterosis provides a basis for genetic diversity and a guide to the choice of parents for developing superior f1 hybrids, so as to exploit hybrid vigour and/or for building better gene pools to be employed in population, improvement (jatothu et al., 2013). information on heterosis in sesame is highly required for breeding work in ethiopia. therefore, the objective of this study was to determine the extent of heterosis for yield and yield related traits in sesame. 2. materials and methods 2.1. planting materials the 10 parental genotypes viz., ew002, bg006, ew023-2, ew006, ew003-1, ew019, obsa, dicho, wama and ew010-1 used in the study (table 1). parental lines, obsa and dicho are released varieties while others were elite breeding lines. initially bako agricultural research center (barc) identified the elite breeding lines among many sesame genotypes collected from western ethiopia. for the crossing purpose, to establish the 10 parents as pure lines, seeds of a single plant from each genotype were collected during 2010 main season. table 1. description of 10 sesame parental lines for selected agromorphology traits they exhibited variations. genotype code collection zone collection altitude (masl) soil texture reaction to bacterial blight ew002 p1 east wellega 1470 clay loam r bg006 p2 benshangul-gumuz 1000 clay loam r ew023-2 p3 east wellega 1580 sandy mr ew006 p4 east wellega 1400 clay r ew003-1 p5 horo-guduruwellega 1346 clay loam r ew019 p6 benshangul gumuz 1095 clay loam r obsa p7 horo-guduruwellega 1395 clay r dicho p8 east wellega 1460 clay mr wama p9 east wellega 1430 clay mr ew010-1 p10 east wellega 1473 sandy loam r note: masl=meters above sea level, df=days to flowering, bp=number of branches per plant, yp= seed yield per plant (g) and oc=oil content (%), r=resistant, mr=moderately resistant. 2.2. experimental sites and experimental procedures ten parental lines were crossed in 10 x 10 diallel mating design, including reciprocals in 2011cropping season. seeds of all 90 f1s and their 10 parents was planted on 12 june 2012 at uke (1383 meters above sea level) and on 14 june 2012 at wama (1436 meters above sea level.) experimental sites of the barc in a randomized complete block design with three replications. each plot consisted of a single row of 5 m length with 50 cm and 25 cm inter and intra-row spacing, respectively. the seeds were drilled in each row at the seeding rate of five kg ha-1. twenty days after planting, the plants were thinned out to adjust for optimum population per hectare. nitrogen fertilizer at the rate of 50 kg n ha-1in the form of urea was applied as side dressing four weeks after emergence. hand weeding was carried out four times at a two-week interval starting 20 days after planting. observations were made on various characters of sesame genotypes (10 parental lines and 90 f1s hybrids) but only four characters of interest in sesame breeding were selected as representative of groups of characters (phenology, growth, yield and oil content) to assess the magnitude of heterosis. data for days to flowering (50%) was registered on a plot basis. observations were made on ten randomly selected plants for number of branches per plant, seed yield per plant, and percentage oil content. oil content of seeds was determined at holetta research center using nuclear magnetic resonance method (robbelen et al., 1989). 2.3. data analysis analysis of variance was performed using sas software to determine the existence of significant variations among parents and crosses for all the traits. the performance of the hybrids was estimated in terms of the percentage increase or decrease of their performance over the mid-parent (heterosis), better parent (heterobeltiosis) (hochholdinger and hoecker, 2007) and standard parent. mid parent heterosis, better parent heterosis (heterobeltiosis) and standard heterosis were estimated following procedure developed by chemeda et al. heterosis for sesame hybrids for agromorphology characters 41 fonesca and patterson (1968). heterosis over mid parent value (hm) was estimated as: (1) where: hm is heterosis over the mid parent value; f1is mean performance of f1; m is mean value of the two parental lines involved in producing that particular f1. heterosis over the better parent (also known as heterobeltiosis) was estimated as: (2) where, hbp is heterosis over the better parent value; f1is mean performance of f1; bp was mean value of the better parent value involved in producing that particular f1. heterosis over the standard variety/check (also known as standard heterosis or commercial heterosis) was estimated as: (3) where: hsv is stanadard heterosis; f1 is mean performance of f1; sv is mean value of the standard/check variety included in the experiment. the mean of two standard checks (obsa and dicho) was used to estimate standard heterosis.the significance of mid parent heterosis was tested as per the method proposed by panse and sukhatme (1961) where critical difference was calaculated as: cd for mid parent heterosis = rxems 23 x ‘’t’’ cd for better parent and standard heterosis= rxems2 x “t” (4) where: r = number of replications, ems = error mean square, t = table value of ‘’t’’ at error degree of freedom at 5% and 1% probability level. 3. results and discussion 3.1. analysis of varaiance and mean performance of genotypes the mean square for the parental lines, f1 cross and reciprocal f1 crosses for all traits at each location was significant, indicating that there was sufficient variability among the genotypes for the traits (data not presented). parental diversity of sesame is desirable to exploit heterosis in its breeding program (das et al., 2013). the analysis of variance (anova) over location for parents, f1 cross and reciprocal f1cross showed that there was a significant variation among genotypes for days to flowering and branches per plant (table 2). similar results were reported earlier for these and other traits in sesame by aladji et al. (2015), pawar and aher (2016), chaudhari et al. (2017) and nayak et al. (2017). table 2. mean squares from combined analysis of variance (anova) over location for phenology and growth characters of three groups of sesame genotypes tested at uke and wama, western ethiopia in 2012. source of variation 10 parental lines 45 f1 crosses 45 reciprocal f1 crosses days to flowering number of branches/plant days to flowering number of branches/plant days to flowering number of branches/plant replication (location) 4.1ns 3.1ns 59.1** 20.7** 20.1ns 26.4** genotype 17.3** 9.7** 21.3** 6.3** 25.2** 7.8** location 0.1ns 0.8ns 9.6ns 2.0ns 34.8 ns 0.9ns genotype x location 1.2ns 7.8** 10.2** 4.8** 15.8ns 4.2** error 4.9 3.0 3.7 1.9 10.9 2.5 note: ns,* and ** non signficant, significant at p< 0.05 and p< 0.01, respectively.degree of freedom for replication (location) and location was 4 and 1, respectively, while for genotype, it was 9, 44 and 44 for parental lines, f 1and reciprocal f1 crosses, respectively. accordingly, degree of freedom for genotype x location and error for parental lines was 9 and 36, respectively, while it was 44 and 44 for both f1and reciprocal f1 crosses, respectively. for yield per plant and oil content, the combined mean square over locations (table 3) was significant for parents, for f1 cross and f1 reciprocal, demonstrating high variability among the genotypes for both traits. this is consistent with the results of studies in sesame by sumathi and murlidharan (2010) and gidey et al., (2013). the mean square for genotype x location was significant for all characters, indicating the importance of testing genotypes over locations. the overall combined anova for all studied traits was highly significant for genotypes and genotype x locations (table 4).this indicates that there is variation among genotypes for all studied characters. combined anova was significant for locations for all traits except branches per plant. table 3. mean squares from combined anova over location for seed yield and seed oil content of three groups of sesame genotypes tested at uke and wama, western ethiopia in 2012. chemeda et al. east african journal of sciences volume 13 (1) 39-50 42 source of variation 10 parental lines 45 f1 crosses 45 reciprocal f1 crosses seed yield per plant (g) seed oil content (%) seed yield per plant(g) seed oil content (%) seed yield per plant (g) seed oil content (%) replication (location) 26,2ns 0.4ns 95.4** 10.2* 83.9** 2.3ns genotype 77.7** 7.9** 44.1** 7.3** 55.1** 3.8** location 2.6ns 14.0** 45.8** 15.6** 132.5** 11.2** genotype x location 29.6ns 1.8* 50.8** 2.5** 52.6** 2.9** error 15.7 0.8 16.3 1.1 15.3 1.4 note: ns,*, ** non signficant, significant at p< 0.05 and p< 0.01, respectively.degree of freedom for replication (location) and location was 4 and 1, respectively, while for genotype, it was 9, 44 and 44 for parental lines, f1and reciprocal f1 crosses, respectively. accordingly, degree of freedom for genotype x location and error for parental lines was 9 and 36, respectively, while it was 44 and 44 for both f1and reciprocal f1 crosses, respectively. table 4. mean squares from combined analysis of variance over locations for yield and related traits of 10 sesame parental lines andtheirf1crossess tested at uke and wama, western ethiopiain 2012. sourceof variation degree of freedom days to flowering number of branches per plant seed yield per plant (g) seed oil content (%) replication (location) 4 61.3 44.8 187.1 9.1 genotype 99 19.4** 7.5** 51.8** 6.5** location 1 20.5* 3.68ns 164.0** 37.0** genotype x location 99 7.5** 4.5** 48.4** 2.6** error 396 4.4 2.3 15.7 1.3 note: ns, *, and ** non signficant, significant at p< 0.05 and p< 0.01, respectively. mean performance of sesame parents for all the studied traits are shown in table 5. days to flowering ranged 65 to 70, the number of branches per plant 5 to 9, seed yield per plant 12 to 17 gram, and oil content of the seed 50 to 54%. parental genotype, ew023-2 had least number of branches per plant, however, with above average seed yield per plant. two parents viz., ew0031 and ew019 had maximum days to flowering, indicating that these lines are important to develop late maturing varieties. parental line, dicho had above average days to flowering, number of branches per plant and seed yield per plant. parental genotype, wama had maximum days to flowering, and above average yield per plant, average number of branches per plant but with below average oil content, indicating that it is important parent for yield per plant. genotype, ew010-1 is a parental line that had very minimum days to flowering, showing that it could be suitable to contribute for early flowering genes. however, it has low oil content among all parental lines with above average yield per plant. table 5. mean performance of 10 sesame parental lines over locations for seed yield and related characters as evaluated at uke and wama, western ethiopia in 2012. parental line code days to flowering number of branches/plant seed yield per plant (g) seed oil content (%) ew002 p1 70 9 17 53 bg006 p2 67 7 16 54 ew023-2 p3 68 5 12 53 ew006 p4 67 8 12 53 ew003-1 p5 70 8 13 52 ew019 p6 70. 8 12 53 obsa p7 68 7 14 52 dicho p8 70 8 16 51 wama p9 70 6 16 51 ew010-1 p10 65 7 15 50 mean 69 7 14 52 parents generally exhibited variable mean performance and none of them had done well for all characters. they are, however, certain parents, which showed good performance for two traits or more. for instance, ew002 had maximum yield per plant, number of branches per plant, and days to flower and with above average oil content. genotype, bg006 is the top ranking parental line for its high oil content with chemeda et al. heterosis for sesame hybrids for agromorphology characters 43 average seed yield per plant. parental line, ew006 had above number of branches and oil content. parental genotype, obsa possessed average number of branches per plant, yield per plant, oil content with below average days to flowering, indicating that this line is desirable for these all traits.such parents possessing with multiple desirable characters may be of great value in sesame breeding program (tripathy et al., 2016). 3.2. heterosis for phenology and growth characters the estimate heterosis mid parent, better parent and standard variety for days to flowering and branches per plant in f1 and reciprocal f1 crosses of sesame is presented in table 6. the mid and better parent heterosis in f1 and reciprocal f1crosses for days to flowering ranged from –12.4 to 5.9% and -14.3 to 5.9%, respectively, while standard heterosis range from -15.0% to 4.3 %. a total 26, 35 and 22 (f1s and reciprocal f1) crosses exhibited negative and significant mid, and better parent and standard heterosis for days to flowering, respectvely. prajapati et al., (2010), reported similar results. four f1 crosses viz., ew002 x ew003-1, bg006 x wama, ew019 x wama, and obsa x dicho showed highly significant negative heterosis over both better and stanadard parents for days to flowering. among which cross ew019 x wama and obsa x dicho were the crosses with the maximum value for their negative standard heterosis. eleven reciprocal f1 crosses such as bg006 x ew002, ew003-1 x ew002, obsa x ew002, wama x bg006, dicho x ew0023-2, ew0031 x ew006,ew019 x ew003-1, wama x ew003-1, ew010-1 x ew019, wama x obsa and ew010-1 x dicho also demonstrated highly significant negative better and stanadard heterosis for days to flwering. out of these wama x bg006 was with the maximum value followed by ew003-1 x ew002. evidently, a large number of crosses showed significant negative heterosis over both better and standard parents, indicating the chances of developing early flowering/maturing genotypes out of the crosscombinations. jatothu et al (2013) reported negative heterosis for days to flowering and were of the view that earliness could be induced in sesame. earliness characters are of paramount importance in breeding for early maturing varieties/hybrids of oilseed crops in general and sesame in particular for better adaptation to climate change (paroda, 2013). selection for maturation period can be effective using flowering period for improving uniform ripening capsule (jamie et al., 2002). a suitable breeding methodology and the identification of superior parents are the most important pre-requisites for the development of early maturing and high yielding genotypes. regarding number of branches per plant, mid, and better parent and standard heterosis ranged from --36.8 to 46.7%, -40 to 22.2% and -36 to 5.3%, respectively. sumathi and murlidharan (2010) reported that number of branches per plant have high association with grain yield in sesame. for number of branches 27, 11 and 7 crosses (f1 and reciprocal f1) displayed significant positive mid, better parent and standard heterosis, respectively.for the same trait, two f1 crosses viz., ew023-2 x ew003-1 and ew023-2 x dicho showed positive and highly significant heterosis over both better and standard parents. four reciprocal crosses such as ew019 x ew002, wama x ew023-2, ew0101 x ew023-2 and dicho x ew006 also demonstrated positive and highly significant better parent and stanadard variety heterosis for the same trait. in the present study for both traits viz., days to flowering and branches per plant majority of the hybrids exhibited negative and significant mid, better and standard parent heterosis, indicating that for these traits the genes with negative effects were dominant. jadhav and mohrir (2013), parimala et al.(2013) and nayak et al. (2017) have also reported both negative and positive signficant heterosis for these and other different traits in sesam. chemeda et al. east african journal of sciences volume 13 (1) 39-50 44 table 6.heterosis over mid, better and standard parents in 45 f1 and reciprocal 45f1 crosses of sesame for phenology and growth characters evaluated over two locations in western ethiopia in 2012. f1 cross days to flowering number of branches/plant reciprocal f1 cross days to flowering number of branches/plant hmp hbp hsv hmp hbp hsv hmp hbp hsv hmp hbp hsv p1xp2 -0.7 -2.9 -1.4 0 -11.1** -15.8** p2 x p1 -3.6* -5.7** -4.5** 12.5** 0 -5.3** p1x p3 0 -1.4 0 0 0 -5.3** p3x p1 -1.4 -2.8 -1.5 0 0 -5.3** p1 xp4 0.7 -1.4 0.0 -17.6** -22.2** -26.3** p4xp1 -2.2 -4.3* -3.0 -5.9** -11.1** -15.8** p1x p5 -7.1** -7.1** -5.8** -17.6** -22.2** -26.3** p5 x p1 -8.6** -8.5** -7.8** -5.9** -11.1** -15.8** p1xp6 -5.7** -5.7** -4.3* -29.4** -33.3** -36.8** p6 x p1 -4.3* -4.3* -3 17.7** 11.1** 5.3** p1 xp7 -1.4 -2.9 -1.4 -15.8** -20.0** -15.8** p7 x p1 -5.8** -7.1** -6.1** -26.3** -30.0** -26.3** p1x p8 -4.3* -4.3* -2.9 -22.2** -22.2** -26.3** p8 xp1 0 0 1.4 -11.1** -11.1** -15.8** p1x p9 -4.3** -4.3* -2.9 6.7** -11.1** -15.8** p9 x p1 0 0 1.4 -6.7** -22.2** -26.3** p1xp10 -0.7 -4.3* -2.9 -12.5** -22.2** -26.3** p10 x p1 -0.7 -4.3* -3.0 -12.5** -22.2** -26.3** p2xp3 2.2 1.5 0 -12.5** -22.2** -26.3** p3 xp2 2.2 1.5 0 12.5** 0 -5.3** p2 xp4 0.0 0 -2.9 20.0** 12.5** -5.3** p4 x p2 -1.5 -1.5 -4.6** 6.7** 0 -15.8** p2 x p5 2.2 0 1.4 -6.7** -12.5** -26.3** p5x p2 -2.2 -4.3* -3.0 20.0** 12.5** -5.3** p2 x p6 3.6* 1.4 2.9 -6.7** -12.5** -26.3** p6 x p2 0.7 -1.4 0.0 -6.7** -12.5** -26.3** p2 xp7 -2.2 -2.9 -4.3* -5.9** -20.0** -15.8** p7x p2 2.2 1.5 0 -17.7** -30.0** -26.3** p2 xp8 -0.7 -2.9 -1.4 0 -11.1** -15.8** p8x p2 -2.2 -4.3* -3 0 -11.1** -15.8** p2x p9 -5.1** -7.1** -5.8** 23.1** 14.3** -15.8** p9x p2 -12.4** -14.3** -15.0** -7.7** -14.3** -36.8** p2x p10 -1.5 -3.0 -5.8** 0 0 -26.3** p10 x p2 4.6** 3 0 -14.3** -14.3** -36.8** p3 x p4 0.7 0 -1.4 -5.9** -11.1** -15.8** p4 x p3 2.2 1.5 0 5.9** 0 -5.3** p3 x p5 -2.9* -4.3* -2.9 17.6** 11.1** 5.3** p5x p3 1.5 0 1.4 -5.9** -11.1** -15.8** p3 xp6 1.4 0 1.4 -17.6** -22.2** -26.3** p6x p3 0 -1.4 0 5.9** 0 -5.3** p3 x p7 5.9** 5.9** 4.3* 5.3** 0 5.3** p7 x p3 1.5 1.5 0 -5.3** -10.0** -5.3** p3 xp8 1.4 0 1.4 11.1** 11.1** 5.3** p8x p3 -5.8** -7.1** -6.1** 0 0 -5.3** p3xp9 4.3** 2.9 4.3* 6.7** -11.1** -15.8** p9 x p3 2.9* 1.4 2.8 46.7** 22.2** 15.8** note: *, and ** significant at p< 0.05 and p< 0.01 level of significant, respectively.hmp, hbp and hsv =heterosis over mid, better and standard parents, respectively.p1=ew002, p2=bg006, p3=ew023-2, p4=ew006, p5=ew003-1, p6=ew019, p7=obsa, p8=dicho, p9=wama, p10=ew010-1. chemeda et al. heterosis for sesame hybrids for agromorphology characters 45 table 6. continued. f1 cross days to flowering number of branches/plant reciprocal f1 cross days to flowering number of branches/plant hmp hbp hsv hmp hbp hsv hmp hbp hsv hmp hbp hsv p3 xp10 3.8** 1.5 0.0 0.0 -11.1** -15.8** p10 x p3 2.3 0.0 -1.5 25.0** 11.1** 5.3** p4x p5 2.2 0.0 1.4 0.0 0.0 -15.8** p5 xp4 -3.6* -5.7** -4.6** 12.5** 12.5** -5.3** p4 xp6 0.7 -1.4 0.0 0.0 0.0 -15.8** p6 x p4 -0.7 -2.8 -1.5 0.0 0.0 -158** p4 x p7 5.2** 4.4* 2.9 -22.2** -30.0** -26.3** p7x p4 -2.2 -2.9 -4.5** -22.2** -30.0** -26.3** p4 xp8 -0.7 -2.9 -1.4 -5.9** -11.1** -15.8** p8 xp4 0.7 -1.4 0 17.7** 11.1** 5.3** p4x p9 0.7 -1.4 0.0 28.6** 12.5** -5.3** p9 x p4 5.1** 2.8 4.2* 14.3** 0.0 -15.8** p4 x p10 4.5** 3.0 0.0 -6.7** -12.5** -26.3** p10x p4 1.5 0.0 -3.0 -6.7** -12.5** -26.3** p5 xp6 -4.3** -4.3* -2.9 -25.0** -25.0** -36.8** p6x p5 -5.7** -5.7** -4.6** 0.0 0.0 -15.8** p5x p7 0.0 -1.4 0.0 -11.1** -20.0** -15.8** p7x p5 -2.9* -4.3* -3.0 -22.2** -30.0** -26.3** p5 x p8 0.0 0.0 1.4 -29.4** -33.3** -36.8** p8 x p5 -1.4 -1.4 0.0 -17.7** -22.2** -26.3** p5 xp9 0.0 0.0 1.4 14.3** 0.0 -15.8** p9 x p5 -5.7** -5.7** -4.6** 0.0 -12.5** -26.3** p5 x p10 -2.2 -5.7** -4.3* 6.7** 0.0 -15.8** p10x p5 -0.7 -4.3* -3.0 6.7** 0.0 -15.8** p6x p7 -2.9* -4.3* -2.9 -22.2** -30.0** -26.3** p7 x p6 -1.4 -2.8 -1.5 -11.1** -20.0** -15.8** p6 xp8 -2.9* -2.9 -1.4 -17.6** -22.2** -26.3** p8x p6 -4.3** -4.3* -3.0 -29.4** -33.3** -36.8** p6 x p9 -8.6** -8.6** -7.2** 0.0 -12.5** -26.3** p9 xp6 -2.8 -2.8 -1.5 14.3** 0.0 -15.8** p6x p10 2.2 -1.4 0.0 -20.0** -25.0** -36.8** p10xp6 -3.7* -7.1** -6.2** -6.7** -12.5** -26.3** p7x p8 -7.2** -8.6** -7.2** -36.8** -40.0** -36.8** p8 xp7 -2.9* -4.3* -3.0 -26.3** -30.0** -26.3** p7 x p9 -1.4 -2.9 -1.4 -25.0** -40.0** -36.8** p9 x p7 -4.4** -5.7** -4.6** -25.0** -40.0** -36.8** p7xp10 3.8** 1.5 0.0 -17.6** -30.0** -26.3** p10xp7 2.3 0.0 -1.5 -5.9** -20.0** -15.8** p8 x p9 -5.7** -5.7** -4.3* -20.0** -33.3** -36.8** p9x p8 -2.8 -2.8 -1.5 20.0** 0.0 -5.3** p8 x p10 2.2 -1.4 0.0 0.0 -11.1** -15.8** p10xp8 -2.2 -5.7** -4.6** -12.5** -22.2** -26.3** p9x p10 0.7 -2.9 -1.4 7.7** 0.0 -26.3** p10x p9 3.7* 0.0 1.4 7.7** 0.0 -26.3** note: *, and ** significant at p< 0.05 and p< 0.01 level of significant, respectively.hmp, hbp and hsv =heterosis over mid, better and standard parents, respectively.p1=ew002, p2=bg006, p3=ew023-2, p4=ew006, p5=ew003-1, p6=ew019, p7=obsa, p8=dicho, p9=wama, p10=ew010-1. chemeda et al. east african journal of sciences volume 13 (1) 39-50 46 3.3. heterosis for seed yield and seed oil content to achieve higher yields in sesame, exploitation of heterosis is the most practical and achievable option. for yield per plant, mid, better and standard parent heterosis was ranged from -40 t0 to 31.6, -46.2 to 23.3 and -41.8 to 13.6 %, respectively (table 7). the total of 32 (f1 and reciprocal f1) crosses revealed positive and significant mid heterosis for seed yield per plant. eight f1 crosses viz., bg006 x ew023-2, bg006 x ew0031, bg006 x ew010-1, ew023-2 x dicho, ew023-2 x wama ew023-2 x ew010-1 ew019 x dicho and dicho x wama were desirable crosses for their better parent heterosis for seed yield per plant. chaudhari et al.( 2015) and das et al. (2013) noted desirable heterosis for seed yield and other yield contributing characters. eight reciprocal f1 crosses such as bg006 x ew002, ew23-2 x bg006, ew019 x bg006, dicho x bg006, ew019 x ew023-2, wama x ew023-2 and wama x dicho were exhibited positive and significant better parent heterosis. similar findings were reported by jadhav and mohrir (2013), vavdiya et al (2013),subashini et al (2014) and chaudhari et al(2017) for seed yield per plant.the best promising crosses for their both better and standard heterosis were f1 cross bg006 x ew03-1 and ew023-2 x dicho and reciprocal f1 cross bg006 x ew002. parents of these crosses are good combiners and could be used for increasing yield per plant in future breeding program. therefore, more emphasis should be given to these crosses for development of varieties with high seed yield per plant. georgiev et al. (2011) and parimala et al. (2013) also reported significant positive heterosis over both mid and better parents for this trait.in this study, the percentage of hybrids significantly superior to the standard check was low, indicating the necessity to make a large number of crosses to obtain heterotic hybrids for economic exploitation of yield per plant (g). on the other hand, for seed yield per plant, 15 f1 cross and 22 reciprocal f1 crosses showed negative and highly significant mid parent heterosis. for the same trait large number of crosses exhibited significant negative better and standard heterisis as compared to mid parent for yield per plant. according to ilker et al. (2010), large negative values of mid parent heterosis and heterobeltiosis were observed for certain hybrids for seed yield per plant that may have accumulated deleterious genes which causes difficulties for selection in breeding program. generally, positive heterosis is desired in the selection for seed yield and its components, whereas negative heterosis is important for early maturty and low plant height (lamkey and edwards, 1999). this shows that both positive and negative heteroses are useful, depending on the breeding objectives. to exploit commercially viable heterosis the new crosses are usually compared with released varieties, so that the crosses with high heterotic potential could be commercialized. from the perspective of the breeder, better parent heterosis (heterobeltiosis) is more effective than mid parent heterosis (relative heterosis), particularly in the breeding of self-pollinating crops where the objective is to identify superior hybrids (lamkey and edwards, 1999). however, in some cases, the yields of f1 hybrids being considerably higher than those of the better parents have been reported (azeez and morakinyo, 2014). the single economic trait in sesame is its oil content. for oil content, a total of 24 f1 crosses for mid, 17 for better and 33 for standard parents showed positive and significant heterosis. among these 12 f1 crosses viz., ew002 x obsa, ew006 xew019, ew003-1x ew019, ew003-1 x obsa, ew003-1 x dicho, ew003-1 x wama, ew003-1 x ew010-1, ew019 x dicho, obsa x dicho, obsa x ew010-1,dicho x wama and wama x ew010-1 exhibited positive and highly significant heterosis over both better and standard parents. f1 cross ew006 x ew019 was the best for its high degree of standard heterosis for oil content, demonstrating that this cross can be used in breeding for high seed oil content. for mid 28, for better 7, and for standard parent 41 reciprocal f1 crosses showed highly positive and significant heterosis for oil content. for oil content, mid, better and standard heterosis was ranged from 3.8 to 8.9, -5.6 to 7.8 and -1 to 8.7, respectively. reciprocal f1 cross ew010-1 x wama was the best for its high better parent and standard heterosis followed by ew023-2 x ew002 and ew006 x ew023-2. the parents of these all crosses have the potential to be used in breeding program. in agreement with this finding, banerjee and kole (2011), salunke and lokesha, 2013) and subashini et al (2014) reported positive and highly significant heterosis for sesame. as compared to other studied traits large number of crosses, showed appreciable advantage over the parents for oil content. generally, heterosis is associated with the nonadditive effects (over-dominance and epistasis) (beche et al., 2013). critical choice of parents is the most crucial step in any breeding program and particularly in heterosis breeding (salunke and lokesha, 2013). in the present study, large number of crosses showed mid parent heterosis than better and standard heterosis for all studied traits except for oil content. on the contrary, sunduri and kumala (2012) reported high number of crosses having standard heterosis than heterosis over mid parent for yield and related traits in sesame. heterotic behavior of crosses with respect to yield and yield related traits differ trait to trait. however, a few crosses such as cross ew023-2 x dicho possessed positive and significant standard heterosis for three traits viz., branches per plant, yield per plant and oil content. cross bg006 x ew003-1 also showed an appreciable level of promising hybrid vigour for yield per plant and oil content. chemeda et al. heterosis for sesame hybrids for agromorphology characters 47 table 7. heterosis over mid, better and standard parents in 90 f1 and reciprocal f1 crosses of sesame for seed yield and seed oil content evaluated over two locations in western ethiopia in 2012. f1 cross seed yield (g) seed oil content (%) reciprocal f1 cross seed yield (g) seed oil content (%) hmp hbp hsv hmp hbp hsv hmp hbp hsv hmp hbp hsv p1xp2 -4.2 -13.3** -17.3** 0.9 0.0 4.9** p2 x p1 31.6** 19.1** 13.6** 2.8** 1.9 6.8** p1x p3 0.5 -11.4** -15.5** 0.0 0.0 2.9** p3x p1 8.1** -4.8 -9.1** 3.8** 3.8** 6.8** p1 xp4 -13.5** -15.5** -15.5** -3.8** -5.6** -1.0 p4xp1 -2.3 -4.6 -4.6 1.9* 1.9 4.9** p1x p5 -40.5** -41.8** -41.8** -1.0 -1.9* 1.0 p5 x p1 -20.9** -22.7** -22.7** 1.0 0.0 2.9** p1xp6 -12.2** -24.8** -28.2** -1.9* -1.9* 1.0 p6 x p1 22.2** 4.8 0.0 0.0 0.0 2.9** p1 xp7 -8.1** -16.9** -1.8 4.8** 3.8** 6.8** p7 x p1 -23.4** -30.8** -18.2** 2.9** 1.9 4.9** p1x p8 -14.9** -21.0** -24.5** 0.0 -1.9* 1.0 p8 xp1 12.8** 4.8 0.0 0.0 -1.9 1.0 p1x p9 11.0** 5.7 0.9 1.9* 0.0 2.9* p9 x p1 -10.0** -14.3** -18.2** 0.0 -1.9* 1.0 p1xp10 22.8** 5.2 0.5 1.0 -1.9* 1.0 p10 x p1 -11.1** -23.8** -27.3** 4.9** 1.9 4.9** p2xp3 19.4** 15.9** -10.5** -0.9 -1.9* 2.9** p3 xp2 15.2** 11.8** -13.6** 0.9 0.0 4.9** p2 xp4 11.3** -1.4 -1.4 -2.8** -3.7** 1.0 p4 x p2 -33.3** -40.9** -40.9** 0.9 0.0 4.9** p2 x p5 24.6** 10.5** 10.5** 0.0 -1.9* 2.9** p5x p2 18.0** 4.6 4.6 3.8** 1.9 6.8** p2 x p6 5 -1.2 -23.6** -2.8** -3.7** 1.0 p6 x p2 25.0** 17.7** -9.1** 2.8** 1.9 6.8** p2 xp7 -21.9** -35.4** -23.6** -1.9* -3.7** 1.0 p7x p2 -2.3 -19.2** -4.6 0.0 -1.9 2.9** p2 xp8 3.4 0.6 -17.7** 4.8** 1.9* 6.8** p8x p2 20.0** 16.7** -4.6 2.9** 0.0 4.9** p2x p9 -5.6* -10.5** -22.7** 2.9** 0.0 4.9** p9x p2 -11.1** -15.8** -27.3** 2.9** 0.0 4.9** p2x p10 15.0** 8.2* -16.4** 3.8** 0.0 4.9** p10 x p2 -6.3* -11.8** -31.8** 1.9* -1.9 2.9** p3 x p4 1.6 -12.3** -12.3** 0.0 -1.9* 2.9** p4 x p3 -15.8** -27.3** -27.3** 3.8** 3.8** 6.8** p3 x p5 12.1** -3.2 -3.2 -1.0 -1.9* 1.0 p5x p3 -21.1** -31.8** -31.8** 2.9** 1.9 4.9** p3 xp6 14.2** 4.1 -19.5** 0.0 0.0 2.9** p6x p3 16.1** 12.5** -18.2** 1.9* 1.9 4.9** p3 x p7 -4.3 -22.7** -8.6** 1.0 0.0 2.9** p7 x p3 -19.1** -34.6** -22.7** 1.0 0.0 2.9** p3 xp8 30.6** 27.8** 29.4** 1.9* 0.0 2.9** p8x p3 11.8** 5.6* -13.6** 0.0 -1.9 1.0 p3xp9 27.4** 17.4** 1.4 1.9* 0.0 2.9** p9 x p3 27.8** 21.1** 4.6 1.9* 0.0 2.9** *, and ** significant at p< 0.05 and p< 0.01 level of significant, respectively.hmp, hbp and hsv =heterosis over mid, better and standard parents, respectively.p1=ew002, p2=bg006, p3=ew023-2, p4=ew006, p5=ew003-1, p6=ew019, p7=obsa, p8=dicho,p9=wama, p10=ew010-1. chemeda et al. east african journal of sciences volume 13 (1) 39-50 48 table 7. continued. f1 cross seed yield (g) seed oil content (%) reciprocal seed yield (g) seed oil content (%) hmp hbp hsv hmp hbp hsv f1 cross hmp hbp hsv hmp hbp hsv p3 xp10 23.2** 12.4** -13.2** 4.9** 1.9* 4.9** p10 x p3 3.2 0.0 -27.3** 2.9** 0.0 2.9** p4x p5 -1.4 -1.4 -1.4 1.0 -1.9* 2.9** p5 xp4 -4.6 -4.6 -4.6 2.9** 1.9 4.9** p4 xp6 3.2 -13.2** -13.2** 5.7** 3.7** 8.7** p6 x p4 -13.5** -27.3** -27.3** 1.9* 1.9 4.9** p4 x p7 -37.9** -42.7** -32.3** 4.8** 1.9* 6.8** p7x p4 -16.7** -23.1** -9.1** 2.9** 1.9 4.9** p4 xp8 15.5** 5.0 5.0 3.8** 0.0 4.9** p8 xp4 -20.0** -27.3** -27.3** 1.9* 0.0 2.9** p4x p9 0.5 -6.4* -6.4* 0.0 -3.7** 1.0 p9 x p4 -22.0** -27.3** -27.3** 3.9** 1.9 4.9** p4 x p10 -20.5** -33.2** -33.2** 4.9** 0.0 4.9** p10x p4 -2.7 -18.2** -18.2** 4.9** 1.9 4.9** p5 xp6 -1.1 -16.8** -16.8** 4.8** 3.8** 6.8** p6x p5 24.3** 4.6 4.6 2.9** 1.9 4.9** p5x p7 -36.3** -41.2** -30.5** 3.8** 3.8** 4.9** p7x p5 -41.7** -46.2** -36.4** 3.9** 3.9** 4.9** p5 x p8 -24.5** -31.4** -31.4** 4.9** 3.8** 4.9** p8 x p5 -5.0 -13.6** -13.6** 2.9** 1.9 2.9** p5 xp9 -11.2** -17.3** -17.3** 6.8** 5.8** 6.8** p9 x p5 -7.3** -13.6** -13.6** 2.9** 1.9 2.9** p5 x p10 14.6** -3.6 -3.6 7.8** 5.8** 6.8** p10x p5 13.5** -4.6 -4.6 5.9** 3.9** 4.9** p6x p7 3.4 -18.5** -3.6 1.0 0.0 2.9** p7 x p6 -12.2** -30.8** -18.2** 1.0 0.0 2.9** p6 xp8 16.4** 6.7* -12.7** 5.8** 3.8** 6.8** p8x p6 -9.1** -16.7** -31.8** 3.9** 1.9 4.9** p6 x p9 -15.3** -24.2** -34.5** 3.8** 1.9* 4.9** p9 xp6 -5.9* -15.8** -27.3** 0.0 -1.9 1.0 p6x p10 6.0 6.0 -27.7** 4.9** 1.9* 4.9** p10xp6 -6.7* -6.7* -36.4** 4.9** 1.9 4.9** p7x p8 -23.2** -35.0** -23.2** 6.8** 5.8** 6.8** p8 xp7 4.6 -11.5** 4.6 2.9** 1.9* 2.9** p7 x p9 -27.6** -37.3** -25.9** 1.0 0.0 1.0 p9 x p7 -28.9** -38.5** -27.3** 4.9** 3.9** 4.9** p7xp10 -9.8** -28.8** -15.9** 5.9** 3.8** 4.9** p10xp7 -17.1** -34.6** -22.7** 3.9** 1.9* 2.9** p8 x p9 21.6** 18.4** 2.3 5.9** 5.9** 4.9** p9x p8 24.3** 21.1** 4.6 5.9** 5.9** 4.9** p8 x p10 9.1** 0.0 -18.2** 1.0 0.0 -1.0 p10xp8 15.2** 5.6 -13.6** 5.0** 3.9** 2.9** p9x p10 7.1* -4.2 -17.3** 5.0** 3.9** 2.9** p10x p9 -23.5** -31.6** -40.9** 8.9** 7.8** 6.8** note: *, and ** significant at p< 0.05 and p< 0.01 level of significant, respectively.hmp, hbp and hsv =heterosis over mid, better and standard parents, respectively.p1=ew002, p2=bg006, p3=ew023-2, p4=ew006, p5=ew003-1, p6=ew019, p7=obsa, p8=dicho,p9=wama, p10=ew010-1. chemeda et al. heterosis for sesame hybrids for agromorphology characters 49 heterosis is a complex phenomenon depending upon the balance of additive, dominance and their interacting components as well as distribution of genes in parental lines.the extent of heterosis relies upon the extent of diversity among parental lines, gene frequency difference between parents and degree of dominance for the particular trait (parimala et al., 2013). like many other crops, the magnitude of heterosis in sesame has been related to the degree of divergence of the parents (yadav et al., 2005). high genetic diversity for ethiopian sesame has been reported earlier by daniel and parzies (2011) and ahadu, (2012). in the present study, for almost all the characters, varying number of crosses depicted heterosis in both positive and negative directions indicating that genes with negative and positive effects or a complementary type of gene interaction or simply correlated gene distribution may seriously inflate the mean degree of dominance and convert partial dominance into apparent over dominance (hayman, 1954). sesame is the most suitable crop for exploiting heterosis on a commercial scale because of low seed rate, high seed multiplication ratio (1:50), epipetalous floral structure enabling easy emasculation and natural out crossing to an extent of 5 to 50 per cent (chaudhari et al.,2017). 4. conclusion from the present study, it can be concluded that cross ew019 x wama, obsa x dicho, wama x bg006 and ew03-1 x ew002 were the top ranking hybrids among eighteen promising crosses for early maturity to better adaptation to climate change. out of seven crosses with high standard heterosis, cross wama x ew023-2 was the best for its maximum value for number of branches. for seed yield per plant, sixteen crosses had high standard heterosis of which bg006 x ew03-1, ew023-2 x dicho and bg006 x ew002 were the best promising. large number of crosses had showed high standard heterosis of which cross ew010-1 x wama, ew023-2 x ew002 and ew006 x ew023-2 were the top ranking for their high value for oil content.the selected crosses for each trait have high potential to be used for recombination breeding to develop high potential pure lines. all parents in the selected crosses can be used for future breeding program of this crop. 5. acknowledgements the authors thank the rural capacity building project for the financial support. they are also grateful to bako agricultural research center for all support given to them during the execution of this experiment. 6. references ahadu menzir, a.2012. phenotypic variability, divergence analysis and heritability of characters in sesame (sesamum indicum l.) genotypes. nature and science 10(10):117-126. aladji a. m. m. i., noubissie,t.j. b., njintang, y.n., nguimbou, r. m. and bell, j. m. 2015. diallel analysis of seed oil content in sesame (sesamum indicum l). journal of global bioscience, 4(3):1735-1746. azeez, m.a. and morakinyo, j.a. 2011. path analysis of the relationships between single plant seed yield and some morphological traits in sesame (genera sesamum and ceratotheca). international journal of plant breeding and genetic,5:358-368. banerjee, p. 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______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: beshirshk2@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) prevalence of protein-energy malnutrition in children under five years of age admitted to pediatric wards at asella referral and teaching hospital, arsi zone, oromiya, ethiopia beshir shaku beriso department of statistics, haramaya university, p. o. box 138 dire dawa, ethiopia abstract: malnutrition is a serious problem in ethiopia as a result of which there is a high rate of mortality of children under the age of five years. the main objective of this paper is, therefore, to identify the prevalence of protein energy malnutrition and determine factors contributing to it for children under the age of five years that were admitted to asella referral and teaching hospital in arsi administrative zone, central ethiopia. data were collected from 367 sample households selected randomly from a total of 6554 respondents. the data were analyzed using descriptive statistics and binary logistic regression model. the results revealed that 12%, 46% and 14% children were underweight, stunted and wasted, respectively. this implied that there is less severe problem form of protein energy malnutrition status. it was also found that sex of children, educational level of parents, distance of work place of caregiver from home, age of children, age of caregiver, marital status, family size, and family income were predictors of protein energy malnutrition. in addition, educational level of parents and economy of parents were important components for ensuring good nutritional of children. therefore, improving parents’ economy and literacy of the community (especially female literacy) is instrumental in minimizing protein energy malnutrition for under five-year children. moreover, it is advisable if nutritional status of children be assessed periodically to monitor the situation and to take appropriate measures for combating and preventing malnutrition in children. keywords: binary logistic regression; nutritional status; protein energy malnutrition. 1. introduction protein-energy malnutrition is manifested primarily by inadequate dietary intakes of protein and energy, either because the dietary intakes of these two nutrients are less than required for normal growth or because the needs for growth are greater than can be supplied by what otherwise would be adequate intakes (kliegman, 2011). the term protein energy malnutrition includes a wide spectrum of malnutrition primarily affecting children in developing countries (infants, preschool). the severe clinical forms are marasmus, kwashiorkor and mixed feature called marasmic-kwash. the milder forms like stunting (chronic form), wasting (acute form) of malnutrition are highly rampant in developing countries (kariuki et al., 2002). globally, protein energy malnutrition continues to be a major health burden in developing countries and the most important factor for illnesses and diseases especially among young children. the who estimates that about 60% of all disease occurring among children aged less than five years in developing countries, could be attributed to malnutrition (faruque et al., 2008; mullero, 2005). the improvements of nutrition, therefore, is the main prerequisites for the reduction of high infant and under five mortality rate, the assurance of physical arouse, social and mental development of children as well as academic achievements (gernaat, 2008). sub-saharan africa bears the brunt of protein energy malnutrition in the world. on average the protein energy malnutrition associated mortality in sub saharan africa is between 25% and 35% (medhyg, 2004; rutherford and mahan, 2005). protein energy malnutrition is mostly common and kwashiorkor is prevalent in children under five years of age whereas marasmus is common in children less than 12 month of age (kariuki et al., 2002). under nutrition is a serious public health problem facing children worldwide particularly developing countries and the causes are multi factorial. the data from who showed that about 6% of all deaths occurring among children aged less than five years in developing countries could be attributed to under nutrition. in addition to this, who estimated that 226 million children are stunted, 67 million are wasted and 183 million are under weight (tadesse, 2005; yamane and daman, 2006). malnutrition in children under five years is a devastating and costly public health problem associated with high morbidity and mortality in the developing world. malnutrition impairs growth and development in children, delays recovery from disease and injury, predisposes to infections and also reduces wellbeing (abdulkarem and jasim, 2009). globally, 148 million under-fives in developing regions are underweight for their age (kamau et al., 2002). in children under five years of age, just over 2 million deaths are directly attributed to stunting, severe wasting, and restricted intrauterine growth, and about 1 million to vitamin a and zinc deficiencies. and again about one-third an estimated 178 million children under age five living in developing countries have stunted growth. in line with mailto:beshirshk2@gmail.com beshir shaku east african journal of sciences volume 13 (1) 81-88 82 this, stunted growth is the most important risk factor for illness and death with hundreds of millions of pregnant woman and children are particularly affected by nutritional status (lisa et al., 2011; who, 2004). malnutrition continues to be a major health problem through developing world particularly in southern asia and sub saharan africa (who, 2004). most studies show that children under the age of five are the worst affected by malnutrition in developing countries. this is because of children of this age require a lot of nutrients not only to grow but also to build immunity against disease (anwar et al., 2010). protein energy malnutrition affects every fourth child worldwide, 150 million (26.7%) are underweight while 182 million (32.5%) are stunted. geographically more than 70% of protein energy malnutrition children live in asia, 26% in africa and 4% in latin america and caribbean. their flight will have begun even before birth with a malnourished mother (israt rayhan and sekander, 2006; sununtar, 2005). in ethiopia child malnutrition is an enormous challenge since as the country had a 10.4 % under-five mortality rate in 2009, of which the majority was linked to severe and mild to moderate malnutrition (mofed, 2002; unicef, 2010). according to ethiopian demographic and health survey in 2016 reports, the stunting (chronic malnutrition) and underweight (chronic and acute malnutrition) in children less than five years of age were 47% and 38%, respectively (csa, 2012). in addition to this, in ethiopia child malnutrition rate is one of the most serious public health problems and the highest in the world (margaret and yaguett, 1976; zewditu et al., 2001). although, the prevalence of child malnutrition in ethiopia shows that, 51%, 47% and 11% of under five-year children are stunted, underweight and wasted respectively and protein energy malnutrition is the major cause of child mortality and is responsible for 85% of under-five mortality (deriak and jellife, 1999; gugsa, 2000). while the problem of malnutrition in ethiopia is relatively well documented, its specific determinants are not well understood. to reduce malnutrition one must understand causes of child malnutrition and factors affecting them significantly impairs growth and development in children, delays recovery from disease and injury, predisposes to infections and also reduces wellbeing in particular and economic growth of countries like ethiopia in general. most previous studies conducted on prevalence and factors of malnutrition status of under five children in different countries used descriptive statistics and chi-square test of association. however, applying descriptive statistics is only used to summarize the information in short form and chisquare test also used to identify the association between the dependent variable and independent variables. however, the current study used descriptive statistics to identify demographic characteristics, socio-economic characteristics, perception of respondents on nutritional status of under five children, and binary logistic regression model to determine factors affecting protein energy malnutrition of under five year children in selected area. the main objectives of this study were, therefore, to assess the prevalence of protein energy malnutrition and the factors associated thereof for under five-year children at asella referral and teaching hospital. 2. data and methodology 2.1. source of data the 2016/17 assessment of the prevalence of protein energy malnutrition on under five-year children admitted to pediatric wards survey of asella referral and teaching hospital was used in this study. the data were collected to provide basic information on the protein energy malnutrition status of under five-year children admitted to pediatrics wards in the hospital. the survey was conducted by the asella referral and teaching hospital in 2016-2017. for the purpose of sample selection, simple random sampling technique was adopted to select a representative sample. finally, after cleaning the data based on relevant variables, this study selected a total of 367 out of 6554 respondents. the sample size was obtained using the following formula:   (1) )1( 2 2 2/ d ppz n    (2) 1         n n n n f where: d is some margin of error to tolerate in estimation; p is the proportion of protein energy malnutrition status (stunting under five year children); q is the proportion of non-stunting children; n is total number of children admitted in hospital; n is sample of selected children using simple random sampling and nf is the sample size calculated based on the total number of children admitted; z is the value of standard normal distribution for a given level of significance ( ). in fixing this sample sizes at ,05.0 400.p were used. the value of p was taken from ethiopian demographic and health survey in 2017 that the prevalence of stunting was 40%. 2.2. methods of data analysis the methods of data analysis used for this particular study were descriptive statistics for describing general characteristics of the respondents. the dependent variable is protein energy malnutrition status of children for binary logistic model, which is categorized as malnourished and notmalnourished. the independent variables included in model are age of child, sex of child, number of siblings, age of caregivers, marital status of caregiver, religion, caregiver beshir shaku protein-energy malnutrition and factors of children under five years 83 distance of work place from home, family income, educational status of parents and family size. 2.2.1. logistic regression model logistic regression analysis extends the techniques of multiple regression analysis to research situations in which the dependent variable is categorical like malnourished/non-malnourished (present/absent). logistic regression allows one to predict a discrete outcome, such as group membership, from a set of independent variables that may be continuous, discrete, dichotomous, or a mix of any of these. generally, the dependent variable for this study is binary which is malnutrition status (malnourished/not-malnourished). logistic regression is much more relaxed and flexible in its assumptions than multiple regression analysis. unlike the multiple regression analysis, the logistic regression does not have the requirements of the dependent variables to be normally distributed, linearly related, nor equal variance with in each group. logistic regression has a peculiar property of easiness to estimate logit differences for data collected both retrospectively and prospectively and this has contributed a lot to its importance in application areas (tabachnik and fidell, 2001). there are two main uses of logistic regression: firstly, to predict the group membership. since logistic regression calculates the probability of success over the probability of failure, the results of the analysis are in the form of an odds ratio. secondly, logistic regression also provides knowledge of the relationships and strengths among the dependent and independent variables. the assumptions of logistic regression are: firstly, the dependent variable must be categorical, the groups must be mutually exclusive and exhaustive; a case can only be in one group and every case must be a member of one of the groups. secondly, the independent variables need not be interval, nor normally distributed, nor linearly related, nor of equal variance within each group (polit, 1996; agresti, 1990). the dependent variable in logistic regression is usually dichotomous, that is, the dependent variable can take the value “1” with probability of being malnourished/presence of pem’’ i ‘’or the value 0 with probability of being notmalnourished/absence of pem’’ i 1 ’’. for example, binary (dichotomous), but logistic regression analysis does not model this outcome directly. rather, logistic regression analysis is based on probabilities associated with the values of y . we assume that y is dichotomous, taking on values of 1 (that is, positive outcome, or success) and 0 (that is, negative outcome, or failure). the probability proportion of 1 i y is defined as )/1( iii xyp  and 0 i y is defined as )0(1  ii yp . because of the reasons discussed above, the logistic regression model was used in order to address the issues under objectives of this study effectively. the logistic model is defined as; let y n 1 be a dichotomous outcome random variable with categories 1 (malnourished) and 0 notmalnourished children. suppose x pn )1(  denote the collection of p predicator variables of y , where,                     npnnn p p xxxx xxxx xxxx ... ...... ...... ...... ... ... 321 2232221 1131211 1 1 1 x is called regression matrix and without the loading column of 1’s is termed as predictor data matrix. then, the conditional probability that a child can be malnourished given the x set of independent variables is denoted by iii xyp  )/1( . the expression i has the form: )3( 11 ' ' ... .... 11 11 e e e e x x i xx xx ppo ppo             where: i is the probability of child i being malnourished, iy is the observed nutritional status of i children’s, 1)1(  p is a vector of unknown coefficients. the model given in equation (3) is logistic regression model. the relationship between the independent and dependent variable is not a linear function in logistic regression; instead, the logit transformation of equation  i yields the linear relationship between the independent and dependent variables. the logit transformation of i is given as follows:   )4(xβ...xβxββ π1 π logπlogit pp22110 i i i         where: yi is the dependent variable which is dichotomous taking the value of 1 if child is a malnourished or 0 otherwise. 0 is the constant term, xi is an independent variable, i=1,2,…,k; p  ,, ,...21 are the coefficients of independent variables. the maximum likelihood and non-iterative weighted least squares are the two estimation methods used in fitting logistic regression model (hosmer and lemeshaw, 1989). when the assumption of normality beshir shaku east african journal of sciences volume 13 (1) 81-88 84 of the predictors does not hold, the noniterative weighted least squares method is less efficient (maddala, 1997). in contrast, the maximum likelihood estimation method is appropriate for estimating the logistic model parameters due to its less restrictive nature of the underlying assumptions (hosmer and lemeshaw, 1989). hence, in this study the maximum likelihood estimation technique is applied to estimate parameters of the model. consider the logistic model ' ' 1    x x i e e   . since observed values of y say, )...,,2,1(' nisy i  are independently distributed as bernoulli with parameter i , the maximum likelihood function of y is given by:   )(5 y βχ1 1 υ βχ1 βχ ...., i ρυ)l(β( i , i i , i , i 1 n 1i n 1i ipi21i ee e χχχυ                          where: ),...,,(' 21 p   the objective of stating likelihood function is to get an estimator )...,,( 10   p  of  which maximizes the likelihood function expressed in equation (5). since the likelihood equations are non linear in the parameters, the newton-raphson iterative maximum likelihood estimation method that expresses   at the thu )1(  cycle of the iteration is expressed as rv uuuu              1 ' 1  , where ,...2,1,0u and v  is a diagonal matrix, )6()()1(            cov i diag iv  with its diagonal elements 1x i . finally,   is the resultant maximum likelihood estimator of  with residual yyr ˆ . newton’s method usually converges to the maximum of the log-likelihood in just a few iteration unless the data are especially badly conditioned (hosmer and lemeshaw, 1989). wald statistic: it is a way of testing the significance of particular independent variables in a statistical model. in logistic regression we have a binary outcome variable and one or more independent variables. for each independent variable in the model there was an associated parameter. the wald test, described by (polit, 1996; agresti, 1990) is one of a number of ways of testing whether the parameters associated with a group of independent variables are zero. if for a particular independent variable of wald test is significant, then we would conclude that the parameters associated with these variables are significantly different from zero, so that the variables should be included in the model. if the wald test is not significant then these independent variables can be omitted from the model. wald 2  statistics are used to test the significance of individual coefficients in the model and are calculated as follows: )7( )ˆ( ˆ j j se z    each wald statistic is compared with a 2  distribution with 1 degree of freedom. wald statistics are easy to calculate but their reliability is questionable, particularly for small samples. for data that produce large estimates of the coefficient, the standard error is often inflated, resulting in a lower wald statistic, and therefore the independent variable may be incorrectly assumed to be unimportant in the model (bewick et al., 2005). likelihood-ratio test: an alternative and widely used approach to testing the significance of a number of independent variables is to use the likelihood ratio test. this is appropriate for a variety of types of statistical models. the likelihood ratio test is better, particularly if the sample size is small or the parameters are large (polit, 1996; agresti, 1990). the likelihood-ratio test uses the ratio of the maximized value of the likelihood function for the full model )( 1 l over the maximized value of the likelihood function for the simpler model )( 0 l . the likelihood-ratio test statistic equals:    8)log(l)log(l2 l l og2 1o 1 o          l it is compared with a 2  distribution with p-k degree of freedom, where p and k are the parameters of simpler model and full model, respectively. this log transformation of the likelihood functions yields a chisquared statistic. as mentioned above, the binary logistic regression was used to analyze the determinant variables that affect prevalence of protein energy malnutrition status in selected area. 3. results 3.1. demographic characteristics of the respondents results of the study show that out of the 367 selected children, 61% were protein energy malnourished whereas 39% were not malnourished. similarly, results revealed that 49% are male and 51% are female. with respect to marital status, 66% of them were married, 12% were single, while 22% were either widowed or divorced. in terms of parents educational status, about 28% of the respondents were uneducated, 25% can read and write, 30% attained primary school, while 17% were above secondary school. the average family size in the study area is 12.30 with standard deviation of 73.64. the study also illustrates that mean age of the children is 26.10 months with standard deviation of 13.70, whereas the mean age of the caregiver is 31.57 beshir shaku protein-energy malnutrition and factors of children under five years 85 years with standard deviation of 6.46. the ethnic composition of the sample households includes 65% oromo, 28% amhara, and 7% belongs to other ethnic group. on the other hand, the distribution of religion from sample households shows that 38% are orthodox, 44% are muslim, and 18% belongs to other religion groups. the distribution of the classification of world health organization (who) standard curve, weight for age, revealed that 12% were underweight children while marasmic, marasmickwash and kwash were not diagnosed. with respect to the classification of height for age, 46% of children were stunted, of which 24% were mild stunted, 14% moderate stunted and 8% severe stunted. in terms of weight for height, about 9% children were wasted. among the wasted children 6% were mild wasted, 5% moderate wasted and 3% severe wasted. the results of the classification of weight for height also show that 7% of them were moderately malnourished, whereas 2% severely malnourished children. when we take measurement of upper arm circumference (muac) into consideration, results indicate that 31% were moderately malnourished and 5% severely malnourished children (table 2). table 1. descriptive statistics of demographic characteristics of respondents. demographic characteristic category/measure value/percent pem status sex of children malnourished not malnourished male 61% 39% 49% female 50% age of children in month mean standard deviation 26.10 13.70 age of caregiver in year mean standard deviation 31.57 6.46 family size mean standard deviation 12.30 73.64 family income mean standard deviation 1070 988 educational status uneducated 28% can read and write 25% primary school 30% secondary school 11% prep. and higher level 6% ethnicity oromo 65% amhara 28% others 7% religion muslim 44% orthodox 38% protestant 18% marital status married 66% single 12% divorced and widowed 22% table 2. the prevalence of protein energy malnutrition of under five year children. who standard curve status/ category count percent (%) weight for age normal (>80%) marasmic (<60%, edema absent) marasmickwash(60-80% with edema) kwash (<60% with edema) underweight(60-80% with no edema) 322 45 88 12 height for age normal (95%) mild stunting (90-95%) moderate stunting (85-90%) severe stunting (<85%) 200 87 50 30 55 24 14 8 weight for height normal (>90%) mid wasting (85-90%) moderate wasting (75-85%) severe wasting (<75%) 315 23 17 12 86 6 5 3 muac normal (>12.5 cm) moderately malnourished (11.5-12.5 cm) severely malnourished (11.5 cm) 235 115 18 64 31 5 3.2. factors affecting pem status of under fiveyear children admitted to pediatric wards factors hypothesized to affect protein energy malnutrition status were sex of children, age of children, age of caregiver, educational level of caregiver, marital status of caregiver, number of siblings, family size, religion of caregiver, family income and distance of work place of caregiver from home. finally, the model beshir shaku east african journal of sciences volume 13 (1) 81-88 86 outputs of factors affecting protein energy malnutrition status of under five-year children are given in table 3. results of binary logistic regression show that among proposed independent variables affecting protein energy malnutrition status, sex of children (female), age of children, age of caregiver or parents, educational level of parents (secondary school and above), marital status of caregiver (divorced and widowed), family size, family income and distance of work place of caregiver from home were found to be statistically significant in this study (table 3). accordingly, sex of children, educational level of caregiver, distance of work place of caregiver from home positively affect protein energy malnutrition status, whereas age of children, age of caregiver, marital status, family size, and family income negatively affect protein energy malnutrition status. the result regarding the variable sex of child shows that female children are 1.684 times more likely malnourished as compared to male children, while the effects of the other variables are constant. the results also show that for an additional year in age of child and caregiver, the odds of malnourished children is lower by a factor of 1.075 and 0.956, respectively. this implies that older mothers or parents have more experience in child care than young mothers and are likely to find solutions to their problems. in line with this, education was grouped into four categories ranging from uneducated to those who have attended higher level (secondary school and above). the odds of being malnourished for uneducated caregivers were found to be 1.018 times higher than those attended secondary school and above. in terms of marital status, the odds of being malnourished for divorced and widowed caregivers were found to be 1.362 and 1.590 times that of those single caregivers (reference category), respectively. table 3. factors affecting pem status of under five year children admitted in pediatric wards. variables coef. s.e z value or sex of child: 1=female age of children age of caregiver educational level of caregiver 2=can read and write 3=primary school 4=secondary school & above marital status of caregiver: 2=married 3=divorced 4=widowed number of siblings family size religion of caregiver: 2=protestant 3=orthodox family income: distance of work place of caregiver from home constant 0.521 0.227 2.30 1.684** -0.072 0.107 -2.45 1.075** -0.460 0.025 -2.37 0.956** 0.101 0.320 0.32 1.107 0.316 0.300 1.05 1.371 0.018 0.421 1.68 1.018* 0.411 0.415 0.99 1.509 -0.309 0.479 -1.72 1.362* -0.464 0.845 -1.76 1.590* 0.120 0.086 1.40 1.127 -0.056 0.072 -2.35 0.946** 0.187 0.338 0.55 1.204 0.430 0.261 0.67 0.651 -0.020 0.010 -2.33 1.020** 0.027 0.021 1.66 1.027* 1.278 0.772 1.66 3.591 log likelihood = -230.18 lr chi2 (16) = 29.40 prob > chi2 = 0.0214 note: *=significant at 0.10; **= significant at 0.05; s.e= standard error; or=odds ratio results show that an increase in family size by one decreases the odds ratio in favor of not malnourished by a factor of 0.946. one birr increment of family income, the odds of lowering malnourished of children increases by 1.020, when other variables remain constant. 4. discussion a number of related studies have been conducted in various parts of the world on the topic. the study conducted by (abdulkarem and jasim, 2009) stated that 22.33% of children were underweight, 31.98% were stunted while 4.35% of them were wasted. in addition, reports in ethiopia shows that 25% were underweight, 25% were stunted and 9% were wasted children. similarly, in oromia region the prevalence of child malnutrition, as reports clarify, is that about 34.4% are underweight children of which 11% are severe underweight, 9.6% of them were wasted (2.4% severe wasted) while 41% were stunted (21.8% severe stunted) (csa, 2012). the study conducted in gindhir hospital revealed that 32.3% were underweight children whilst 17.6% were marasmic, 10.6% were marasmickwash and 4.1% were kwashy children. the result of this study also expressed that 34.7% were stunted (14.4% severe beshir shaku protein-energy malnutrition and factors of children under five years 87 stunted) whereas 42.4% were wasted (16.3% severely wasted) (abdi et al., 2012). in line with this, the study conducted in gimbi district, oromia region shows that 32.4% children were stunted, 15.9% underweight and 23.5% wasted (kebede et al., 2007). although, the finding in gobu seyo district by (gemede et al., 2014) on the prevalence of malnutrition of children age 36-72 months shows that 49% of children were stunted. in contrary to this, the present study illustrated that 12% were underweight children while severe form of protein energy malnutrition (marasmic, marasmickwash and kwash) were not diagnosed or absent. the present finding also indicated that 46% were stunted with 8% severely stunted and 14% wasted with 3% severely wasted. with regard to the prevalence of underweight, the level found in the current finding (12%) is lower than the level reported 32.3%, 22.33%, 25%, 15.9% (abdi et al., 2012; abdulkarem and jasim, 2009; csa, 2012; kebede et al., 2007) and the level of severe stunting found in the current study (8%) is less than the level reported 14.4%, 21.8% (abdi et al., 2012; csa, 2012). according to the study conducted by (fuad et al., 2017), the results show that the prevalence of stunting, wasting and underweight were 36.07% (11.44%, severe stunting), 14.43% (6.72%, severe wasting) and 23.63% (6.47%, severe underweight), respectively. regarding the related factors of malnutrition status this study used chi-square test of association and the result revealed that age of child, sex of child, diarrhea infection, employment status of the mother, and household food security status were significant predictors of nutritional status of the children. the current finding is in agreement with this study regarding some predictors of nutritional status (sex of child and age of child); but, it contradicts with this study on the statistical model used and other predictors of malnutrition status. this finding in the study by (fuad et al., 2017) used chi-square test of association whereas the present study applied logistic linear regression model which was employed to determine factors of protein energy malnutrition status and it is advanced than the earlier statistical model used. the finding of the present study revealed that age of caregiver, educational level of caregiver, marital status of caregiver, family size, family income and distance of work place of caregiver from home were other predictors of protein energy malnutrition. on the other hand, study conducted by (tsedeke et al., 2014), shows that the overall prevalence of malnutrition in the community was high with 43.6% of the children being underweight, 53.1% stunted, and 28.2% wasted. prevalence of severe stunting, underweight and wasting were 2.50%, 0.30% and 0.80% respectively. this finding also applied logistic regression model to determine the predictors of malnutrition status and the results show that age of child and economic status of parents were significantly affect the malnutrition status of children in the selected area. the present study is in agreement with this finding regarding statistical model used and some predictors of malnutrition status (age of child and economic status of parents). but, it contradicts with this study concerning the other predictors of malnutrition status such as sex of child, age of caregiver, educational level of caregiver, marital status of caregiver, family size and distance of work place of caregiver from home were which are found to be determinants of protein energy malnutrition status. as mentioned above, most previous studies have employed different methods of data analysis and revealed different results on the prevalence of malnutrition status. this difference of results might be attributed to the study period and study area. 5. conclusions and recommendations the study has revealed that there is a low rate of malnutrition among children admitted in to asella referral and teaching hospital. this diagnostic study revealed less severe form of protein energy malnutrition status (underweight, wasting and stunting) but severe form of protein energy malnutrition like marasmus, marasmickwash and kwash were absent. in addition, the study revealed that educational level of parents is an important component for ensuring good nutritional of children, which implied that higher education level of parents is instrumental in minimizing protein energy malnutrition. similarly, the economy of parents is an essential component to reduce the malnutrition of under five-year children. based on the findings of this study, the recommendations or policy implications that can be drawn includes the right for education and achieving 100% literacy will definitely go a long way in improving the nutritional status of under five-year children. also, improving economy of parents is important for enhancing nutritional status of under five-year children. moreover, it is advisable if nutritional status of children be assessed periodically to monitor the situation and to take appropriate measures for combating and preventing malnutrition in children. 6. acknowledgments the author sincerely acknowledges haramaya university, college of computing and informatics, department of statistics for allowing me to undertake this study with great encouragement and providing facilities for conduct of the research work. the author also indebted to management of arsi university asella referral and teaching hospital for allowing me to have access to the pertinent medical registers from which the author extracted the data used in this study. finally, the author is grateful to central statistical agency (csa) of ethiopia for providing me with the necessary materials and for making the data ready for analysis. beshir shaku east african journal of sciences volume 13 (1) 81-88 88 7. references abdi a., adeba a. and wondu g. 2012. assessment of prevalence of protein energy malnutrition among under five children. journal of applied science and research 1:50-72 abdulkarem k. and jasim a. 2009. malnutrition in children admitted to karbala pediatric teaching hospital: prevalence and associated risk factors. journal of medical science 12(2):215-230. anwar, f., thomson, a., and riyadi h. 2010. high participation in paysandú nutrition program improved children nutritional status. journal of food science and nutrition practice 4(3):208-214. bewick v., cheek l., and ball j. 2005. statistics review 14: logistic regression. critical care, landon, england, 9(1): 112-118. csa (central statistical agency). 2012. ethiopia demographic and health survey 2011. addis ababa, ethiopia. deriak, b. and jellife, m. 1999. child nutrition in developing countries, universities of west indians, jamaica, 1,118. fao (food and agriculture organization). 2012. the state of food insecurity in the world 2012. economic growth is necessary but not sufficient to accelerate reduction of hunger and malnutrition (fao) rome, italy 1-61. faruque, a., ahmed a., and hassan, m. 2008. nutrition for healthy children and mother in bangladesh. health popular ;210-213 fuad r., gudina e., adem k. 2017. prevalence of malnutrition among children aged 6-59 in haramaya district, oromia, ethiopia. journal biometry and biostatistics 8: 114-118. gemede f., tolera g., wirtu d. 2014. prevalence of wasting and associated factors among preschool children in gubo sayo, east wollega, ethiopia: journal of food science and quality management 28:125135. gernaat h. dechoring w. and voorhees w.2008. mortality in sever protein energy malnutrition at nichelenge zambia. journal of trop pediatrics 44(4):211217 gugsa y., ejhd. 2000. malnutrition among children in southern ethiopia, levels and risk factors 14(3): 283-292. hosmer, d.w. and lemeshaw. 1989. applied logistic regression, wiley, delhi. israt rayhan. md. and sekander h. k. 2006. factors causing malnutrition among under five children in bangladesh, pakistan journal of nutrition 5 (6): 558-562. kamau, t. f., omwega, a.m. and muita, j. w. 2002. childcare practices and nutritional status of children age 0-2 years in thika, kenya. east african medical journal 79(10): 524-529. kariuki, f., monari, j. and kibui, m. 2002. prevalence and risk factors of malnutrition 51:44–50. kebede e. 2007. prevalence and determinants of child malnutrition gimbi district, oromia region, ethiopia: an m.sc. thesis submitted to the graduate studies of addis ababa university, addis ababa. kliegman, b. (2011). text books of pediatrics, 19th edition. lisa a.b., belinda s.g., and timothy c.c. 2011. hospital malnutrition: prevalence, identification and impact on patients and the healthcare system. international journal of environment and res public health 8: 514-527. maddala g.s. 1997. introduction to econometrics 2nd edition. margaret, c. and yaguett, v. 1976. manual on feeding children and infants, 2nd edition. medhyg, k. r.2004. management of protein energy malnutrition in nigeria, an evaluation of regimen at the kersey nutrition rehabilitation center, nigeria. journal of food science 88:594-599. mofed (ministry of finance and economic development). 2002. development and poverty profile of ethiopia. welfare monitoring unit of finance and economic development. federal democratic republic of ethiopia, addis ababa. mullero, k. 2005. malnutrition and health in developing countries 173(3); 279 polit c.v.1996 and agresti p.r. 1990. introduction to logistic regression 3rd edition. rutherford, g., and mahan j. a. 2005. prevalence of malnutrition and causes and rates of death and illness among dislocated persons in gaza and in habana provinces. journal of trop pediatrics 31:143-149 sununtar, s. 2005. child malnutrition as poverty indicator, an evaluation in the context of different development interventions in indonesia. tabachnik, b. g and fidell, l.s. 2001. using multivariate statistics, boston: allyn and bacon. tadesse b. 2005. assessment of causes of malnutrition in ethiopia. tsedeke w., tefera b., and tadesse b. 2014. prevalence of under nutrition and determinant factors among preschool children in hawassa, southern ethiopia. food science and quality management 20:65-72. unicef (united nations children’s fund). 2010. strategy for improved nutrition of children and women in developing countries, new york. who (world health organization). 2004. united nation children’s fund joint statement on the management of acute diarrheal, geneva. who (world health organization).2004. why have mortality rate for severe malnutrition remained so high? yamane b. and daman h. 2006. helmutic loos; epidemiology and ecology of health and diseases in ethiopia, 1st edition: 330-371. zewditu et al, ejhd. 2001. review of the status of malnutrition and trends in ethiopia 15(2): 55-74. microsoft word m_ms-no-04-2019_the comment to be sent to prof east african journal of sciences (201 ______________________________________________________________ licensed under a creative commons attribution-noncommercial 4.0 international license. consumption habit and food sources in haramaya district, ethiopia daniel alemu1* and anbesse girma2 1haramaya institute of technology, food technology and process engineering 2haramaya institute of technology, food science and postharvest technology abstract: haramaya is among the localities that considered as food insecure and poor consumption habit. the study was intended to investigate consumption habits and food patterns o district. data on available raw materials of food sources and the habit of consumption in four kebeles were collected. the result described that area and of total accessible cereals in the area, 65.6% of them are obtained from subsistent farming of own-land production and the remaining, 34.4%, from the market. are the main foods for consumption prepared from cereal grains. among the legumes and pulses, pea, common bean and chickpea are the key food sources, but the majority (54.2%) consume rarely. similarly, though a high quantity of fruit and vegetabl adequate and the same for meat and dairy products. food sources exists, consumption habit is unbalanced due to poor diversified foods. the households entirely depend on cereal grains with minimal consumption of other food sources. therefore, balanced food preparation and consumption education programs are needed to create awareness on diversified eating habit and its benefit. hence, dissemination of proper food nutrition concepts within the community is vital. keywords: food habit; food sources; food type; food diversification; haramaya district 1. introduction the world’s population is expected to grow to almost 10 billion by 2050 boosting agricultural food demand (chauvin et al., 2012). the growth would accelerate the demand of consumption requiring proper utilization and high production to feed the future. ethiopia is a country primarily relies on agricultural based economy where grains are the most important crops and the chief component in the diet of most ethiopians 2009). the principal grains are teff, wh sorghum and millet. it has been also reported that ethiopia has experienced a positive growth rate in oil crops, fruit yields and tuber crops in addition to cereal grains to secure the food demand of the country 2017; chauvin et al., 2012). according to the united nation report, ethiopia is the poorest country in the world with a low human development index and high vulnerability with severe food insecurity (european-commission, 2017) the country showed successive economic growth in the last few years, the problems are still remain on the ground. most of these food insecure populations are subsistence farmers and vulnerable to weather fluctuation. high population growth has also contributed to the decline in farm land size and environmental degradation remains a problem. dramatic variation in rainfall and repeated environmental shocks further contribute to poverty and food insecurity ethiopia is the second most populated nation in africa making the weight of fighting food insecurity even african journal of sciences (2019) volume 1 ______________________________________________________________ *corresponding author. e-mail: danimerry21@gmail.com noncommercial 4.0 international license. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992 consumption habit and food sources in haramaya district, ethiopia haramaya institute of technology, food technology and process engineering haramaya institute of technology, food science and postharvest technology haramaya is among the localities that considered as food insecure and poor consumption the study was intended to investigate consumption habits and food patterns o . data on available raw materials of food sources and the habit of consumption in four kebeles were collected. the result described that sorghum and maize are main cereal grains abandoned in the area and of total accessible cereals in the area, 65.6% of them are obtained from subsistent farming of land production and the remaining, 34.4%, from the market. injera, shumo, genfo, kita are the main foods for consumption prepared from cereal grains. among the legumes and pulses, pea, common bean and chickpea are the key food sources, but the majority (54.2%) consume rarely. similarly, though a high quantity of fruit and vegetables are available, household consumption is not adequate and the same for meat and dairy products. though sufficient distribution and availability of food sources exists, consumption habit is unbalanced due to poor diversified foods. the households depend on cereal grains with minimal consumption of other food sources. therefore, balanced food preparation and consumption education programs are needed to create awareness on diversified eating habit and its benefit. hence, dissemination of proper food preparation, good eating habit and nutrition concepts within the community is vital. food habit; food sources; food type; food diversification; haramaya district the world’s population is expected to grow to almost 10 billion by 2050 boosting agricultural food demand . the growth would accelerate the demand of consumption requiring proper utilization and ethiopia is a country primarily relies on agricultural based economy where grains are the most important crops and the chief component in the diet of most ethiopians (abegaz, . the principal grains are teff, wheat, barley, corn, sorghum and millet. it has been also reported that ethiopia has experienced a positive growth rate in oil crops, fruit yields and tuber crops in addition to cereal grains to secure the food demand of the country (eu, according to the united nation report, ethiopia is the poorest country in the world with a low human development index and high vulnerability with severe commission, 2017). although the country showed successive economic growth in the last few years, the problems are still remain on the ground. most of these food insecure populations are farmers and vulnerable to weather fluctuation. high population growth has also contributed to the decline in farm land size and environmental degradation remains a problem. dramatic variation in rainfall and repeated environmental shocks further to poverty and food insecurity (piguet, 2003). he second most populated nation in africa making the weight of fighting food insecurity even heavier (mihiretu, 2008). studies indicated that the problems are high in east hararghe zone of ethiopia and could span throughout the life if intervention is delayed (piguet, 2003). east hararghe zone is a complex agro-ecological area in which heavy population density with a high ratio of cash to food crops insecurity remains as the major challenges to achieve development in ethiopia especially in the area including haramaya districts (gibson and anderson, 2009) recent study indicated that among the reasons for food insecurity in haramaya area, in some locations, is the result of dependency on undiversified food al., 2018). the degree and distribution of under micronutrient deficiency in a given population depends on many factors including the eco education level, sanitation practices, season of production, food production volume, culture and religious food custom or taboos and effectiveness of the nutritional program (bedeke, 2012) dietary diversity and micro consumption and problematic feeding pra to the high rate of undernutrition assure proper nutrition of a country good care and feeding practices, food preparation and diversity of diet and intra-household distribution of food should be guaranteed (bedeke, 2012; researches indicated that nutritional problems lead to less mental and physical development of the community (gibson and anderson, 2009) volume 13 (2) 207-212 danimerry21@gmail.com 8195 (online), issn 1992-0407(print) haramaya is among the localities that considered as food insecure and poor consumption the study was intended to investigate consumption habits and food patterns of haramaya . data on available raw materials of food sources and the habit of consumption in four kebeles sorghum and maize are main cereal grains abandoned in the area and of total accessible cereals in the area, 65.6% of them are obtained from subsistent farming of kita, wot and kolo are the main foods for consumption prepared from cereal grains. among the legumes and pulses, pea, common bean and chickpea are the key food sources, but the majority (54.2%) consume rarely. es are available, household consumption is not though sufficient distribution and availability of food sources exists, consumption habit is unbalanced due to poor diversified foods. the households depend on cereal grains with minimal consumption of other food sources. therefore, balanced food preparation and consumption education programs are needed to create awareness on diversified preparation, good eating habit and . studies indicated that the problems are high in east hararghe zone of ethiopia and could span throughout the life if intervention is . east hararghe zone is a complex ecological area in which heavy population density with a high ratio of cash to food crops existed. food insecurity remains as the major challenges to achieve development in ethiopia especially in the area including (gibson and anderson, 2009). a recent study indicated that among the reasons for food insecurity in haramaya area, in some locations, is the result of dependency on undiversified food (mulugeta et the degree and distribution of under-nutrition and micronutrient deficiency in a given population depends on many factors including the economy development, education level, sanitation practices, season of production, food production volume, culture and religious food custom or taboos and effectiveness of the (bedeke, 2012). in addition, lack of dietary diversity and micro-nutrient dense food consumption and problematic feeding practice contribute to the high rate of undernutrition (khaeron, 2016). to proper nutrition of a country good care and feeding practices, food preparation and diversity of diet household distribution of food should be (bedeke, 2012; uehara, 2012). many researches indicated that nutritional problems lead to less mental and physical development of the community (gibson and anderson, 2009). proper use helps to daniel and anbesse east african journal of sciences volume 13 (2) 207-212 208 reduce poverty and improve the wellbeing of the community through better access to a good diet. failure of proper use of a food product, which is available in the area, could lead to malnutrition. there is scanty report on the availability, utilization of food source for consumption and feeding practice in the study area. therefore, this study generally attempted to identify the availability of food source, type of foods, way of consumption and feeding practice in the haramaya district. 2. materials and methods 2.1. description of the study area east hararghe zone, located in the oromia region, consists of 17 districts among which haramaya is the one. it is located 18 km away from harar city and about 508 km east of the capital city, addis ababa. the district has uneven rainfall distribution, short rainy season occurring between february and may while the longer occurs between the months of june to september. the mean annual rainfall is 492 mm, which vary between 118 and 866 mm and located at 420 30’e, 90 26’n. the district has 33 rural kebeles with main crops of sorghum, maize and common bean, groundnut, potato, onion, khat and other vegetable crops. the most regular cash crops for the district are vegetables and khat. 2.2. approach and data collection a general survey model was used to collect data through questionnaires which include series of open ended questions. data gathering was conducted on production and utilization of cereal grains, legumes, fruit, vegetable, root-tuber and animal food source. data on consumption habit and method of food preparation in four randomly selected kebeles (damotta, finqile,tinke and gandalafe) around haramaya university was collected. each kebeles contain an estimated population size less than 2000 (administrative office). a total of 150 representative sample households were interviewed based on population size of the study area (hamed, 2017). a simple descriptive statistics used to express frequency and simple comparison. the field data collection involved a combination of a qualitative and quantitative descriptive survey. 3. result and discussions 3.1. production and consumption of cereal grains grains are energy dense food sources which is about 1020 times more energy than from fruit and vegetables (sidhu et al., 2007). they are important sources of dietary protein, carbohydrates, the b complex of vitamins, vitamin e, iron, trace minerals and fiber (demissie et al., 2009). it has been estimated that global grain consumption directly provides about 50% of the protein and energy necessary for the human diet (mkumbwa, 2012). consumption of whole grain is more important than consuming the refined flour due to high minerals and fiber content of the hull and bran (courtin, 2014). figure 1. common grains in the study area both on the farm and market place the most important agricultural crops available in the area mainly are sorghum and maize (figure 1). sorghum and maize are the two main kinds of cereal grain abandoned in the area and obtained from farmland production. according to many literatures, the common staple grain in many small farm land owners are grains such as maize, sorghum and wheat (gray and abu, 2013).the common ways of obtaining the grains are both from subsistent own-farm production and purchasing from the market. from the total accessible cereals, 65.6% of them are obtained from own-land production and the remaining 34.4%, especially wheat and barley, from the nearby market. wheat is obtained from the market and its use for household consumption, in a range of products, is vital. from the total respondents, 65.4% of them explained that cereal grains are the main dish for daily bases but 34.6% of them add other food items beside to cereal grains. 50.8961355 3 45.4429781 5 1.830443 16 1.830443 16 0 20 40 60 sorghum maize wheat barley a va il ab il it y, % daniel and anbesse consumption habit and food sources in haramaya district 209 figure 2. the main household products for consumption made from cereal grains the common household products prepared by the community are injera, shumo (local language for boiled grain), genfo (porridge), kita (unfermented bread), wot (stew) and kolo (toasted grain). among them, shumo, genfo and kita are produced in a high amount respectively. including those purchased foods (bread and pasta) household food security of the community depends on these main products (figure 2). now a days, creation of awareness on food diversification is common in different world (rashid, 2010). hence, educating these communities to diversify their eating habit through different means is important. 3.2. production and consumption of legumes and pulses legumes and pulses contain a high amount of proteins and other components including various enzymes, protease and carbohydrase inhibitors, and lectins (kabata et al., 2017) ). most of the proteins are water-soluble, functional proteins as distinct from storage protein. the various proteins are composed of essential and nonessential amino acids; some contains more of certain individual essential amino acids than others. pulses and legumes are usually mixed with other grains such as sorghum and maize to enhance the protein content and these activities need to be promoted for a better result (dias, 2012). besides the agricultural cereal grains, legumes and pulses are common for consumption (figure 3). pea found in high amount (80.7%) compared to the others followed by common bean (10.1%) and chickpea (7.3%). from the total respondents, only 8.3% of them use legumes and pulses in their daily food schedule. according to gibson et al, (2009), including pulse and legume in the diet, helps to provide range of nutrients in addition to using as a cash crop. the majority (54.2%) consume once or twice a month and the remaining (37.5%) uses occasionally. the main products prepare from these raw materials are shumo (local language for boiled grain and legumes mixes) and wot indicating that no various products produced for consumption. legumes and pulses contain nutrients which are lacking in cereal grains; therefore, incorporation of these food items in household’s menu is important. figure 3. common legumes and pulses found in the area both from the farm and market place (a) and consumption frequency (b). rarely: once or twice a month, sometimes: three-ten times a month, often: more than ten times a month 81.35710576 6.924009001 5.193006751 3.486238532 1.73100225 1.743119266 0 20 40 60 80 injera shumo genfo kita wot kolo h o us eh o ld p ro d uc ts , % 7.338237722 10.11209158 80.70226935 1.847401347 0 20 40 60 80 100 chickpea bean pea habsh a va il ab il it y, % 54.16666667 37.5 8.333333333 0 10 20 30 40 50 60 rarely sometimes often c o n su m p ti o n fr eq ., % frequency daniel and anbesse east african journal of sciences volume 13 (2) 207-212 210 3.3. production and consumption of vegetables compared to other food group’s nutrient profiles, fruits and vegetables provide the nutrient characteristics that most consumers perceive as health promoting. they contain no cholesterol, very little fat, sugar, and sodium, yet provides concentrated sources of many vitamins and minerals. consumption of fruit and vegetables provides minerals, antioxidants, vitamins and most importantly they deliver phytochemicals (demissie et al., 2009). most of the components such as antioxidant can scavenge free radicals before damaging cellular components preventing cancer and related disease (jongen, 2002). as indicated earlier, the consumption of fruit and vegetables has a vital use in providing a diversified nutrient. there are lots of fruit and vegetables in the study area; however, consumption is very minimal as confirmed by the finding indicated in the graph below (figure 4). it can be concluded that the majority of the respondent (36%) do not consume as part of their diet, only 32% of them in a regular base. this might be due to the lack of knowledge of how vital they are for the wellbeing of their family and community. they are more focused on taking to the market for cash. moreover, consuming a diet high in fruit and vegetables is associated with lower risks for numerous chronic diseases, including cancer and cardiovascular disease. replacing foods of high energy density with food such as fruits and vegetables provides an active life with healthy body weight proportion (kader, 2001). figure 4. major vegetables in haramaya district (sources are both from own-farm and market) 3.4. production and consumption of meat and dairy products meat and poultry are nutritious because of their high source and quality of protein, vitamins, and minerals. for example, a typical cut of beef may contain 60% water, 21% fat, 18% protein, and 1.0% ash (lawrie and ledward, 2006). they are also a good source of fatty acids especially omega fatty acids. a well-balanced diet that includes variety of meat and poultry can contribute to heart health and children’s proper growth and development. the increased pressure on the livestock sector to meet the demand for high-value animal protein is expanding. there is a positive relationship between the level of income and consumption of animal products. consumption of milk in the area is relatively higher than the egg and meat. among the total respondents, 8% of them consume meat and dairy products on a regular basis whereas 72% of them use once a month. consumption of meat, milk and eggs is usually in the expense of staple foods. due to this, as a developing country, the consumption of these products is minimal in the study area even though it provides essential nutrients to the households. through different means, it is better to create awareness in society how good these food sources are from a nutritional point of view (lawrie and ledward, 2006). 3.5. overall consumption of foods and drinks the proportion of food and drinks consumed by the community varies a lot and the most frequently used food and drink items are shown in the graph below. consumption of injera, which is a staple food in ethiopia, is very high (rashid, 2010). according to the data collected, 47.7% from the total consumption is injera. it is prepared from blends of sorghum and maize, in most case with a 70% to 30% ratio respectively. the mixing is done not for the nutritional purpose; it is for ease of processing. besides, injera, porridge and bread, pasta consumption is high in the community. boiled grain-legumes-pulses mix and toasted grains are also common and have equal 2.3% shares from the total dish. unlike injera, porridge, toasted grain and boiled grain-legumes mix which is home-made, bread and pasta are purchased from the market. according to the survey, 73.1% of them have the capacity to purchase food items from the market. capacity to buy items from the market is developed due 21.46389713 13.55093966 18.19980218 14.04549951 4.352126607 1.879327399 6.231454006 3.758654797 3.659742829 3.659742829 0 5 10 15 20 25 potato onion carrot cabbage tuber-red sweet potato tomato currumba chilli spinach p ro d u ct io n ,% daniel and anbesse consumption habit and food sources in haramaya district 211 to the common cash crop, khat, abounded in the area (piguet, 2003). the remaining 26.9% of the respondents do not have the capacity to do that. figure 5. major foods and drinks consumed in four kebeles of haramaya district usually, the communities prepare food from sorghum and maize or a mix of the two. a habit of mixing cereals with other food items for a better nutrient is not common and should be disseminated to the community through different means such as training. most of the respondents were replied that they have a habit of mixing not for nutritional profit. they simply added that mixing ingredients would benefit for ease of processing. the most common drinks in the area are hoja, tea, coffee and milk. hoja is among the traditional hot drink, which is consumed in a high amount (47.1%, compared to other drinks) followed by tea and coffee. hoja is prepared by boiling dry coffee pulp (after the seed is removed) with water and salt (similar to tea boiling) rarely they add milk and sugar is added at the end. literatures are limited about traditional hot drinks in the study area. but, due to their importance from nutritional point of view, it is recommended to use them in a daily bases. 4. conclusion sorghum, maize, legumes, pulses, fruits and vegetables including cabbage, potato, carrot and tomato are commonly produced in many parts of the study areas. though food items are not scarce in the area, there is still poor consumption habit in the community. lack of awareness of balanced food preparation and its benefits is a reason for poor consumption and non-diversified food eating. therefore, it is recommended to create awareness on balanced food preparation and benefit of consumption through different means, such as mass media, (radio and television) and conducting training. besides the aforementioned factors, a combination of different factors, especially low production, lack of proper food preparation and low digestibility of proteins from major sorghum-based food products are the key areas that need technological intervention in order to improve the quality of community life. the outcome of this research can be used as a baseline for any activity to be conducted in the area. 5. references abegaz, g.a. 2009. cereal productivity in ethiopia: an analysis based on erhs data. , 1–28. bedeke, s. b. 2012. food insecurity and copping strategies : a perspective from kersa. food sci. qual. manag., 5, 19–27. 47.72727273 22.72727273 20.45454545 4.545454545 2.272727273 2.272727273 0 5 10 15 20 25 30 35 40 45 50 injera bread pourage pasta toasted grain boiled g, l & p consumption, % food 14.70588235 17.64705882 20.58823529 47.05882353 0 5 10 15 20 25 30 35 40 45 50 milk coffee tea hoja consumption, % drinks daniel and anbesse east african journal of sciences volume 13 (2) 207-212 212 chauvin, n. d., mulangu, f. and porto, g. 2012. food production and consumption trends in subsaharan africa : prospects for the transformation of the agricultural sector. courtin, p.c. 2014. cereal science and technology, belgium, leuven: unpublished manuscript. demissie, t., ali, a. and zerfu, d. (2009) availability and consumption of fruits and vegetables in nine regions of ethiopia with special emphasis to vitamin a deficiency. ethiop .j. heal. dev, 3: 216–222. dias, j. s. 2012. nutritional quality and health benefits of vegetables : a review. food nutr. sci., 2012, 1354–1374. european-commission. 2017. eurostat handbook for annual crop statistics ( regulation ( ec ) no 543 / 2009 , commission delegetad regulation ( eu ) 2015 / 1557 and ess agreement for annual crop statistics ) revision 2017 ( released 9 february 2017 ),. gibson, r. s. and anderson, v. p. 2009. a review of interventions based on dietary diversification or modification strategies with the potential to enhance intakes of total and absorbable zinc. food nutr. bull., 30, 108–143. gray, q. and abu, t. (2013) ethiopia grain and feed annual report, addis abeba. hamed, t. (2017) determining sample size ; how to calculate survey sample size 1 survey sample size. int. j. econ. manag. syst., 2: 237–239. jongen, w. 2002. fruit and vegetable processing, north america by crc press llc, 2000 corporate blvd, nw boca raton fl 33431, usa. kabata, a., henry, c., moges, d., kebebu, a., whiting, s. and regassa, n. 2017. determinants and constraints of pulse production and consumption among farming households of ethiopia. , 6: 41–49. kader, a. 2001. importance of fruits, nuts, and vegetables in human nutrition and health. perishables handl. q., 4. khaeron, e. h. 2016. assessment of sustainable food diversification development model in west java , indonesia. int. j. humanit. soc. sci., 6, 175–181. lawrie, r. a. and ledward, d. a. 2006. meat science seventh ed., england: woodhead publishing limited, abington hall, abington cambridge cb1 6ah, england. mihiretu, t. a. 2008. farmers’ evaluation and adoption of improved onion production package in fogera district, south gondar, ethiopia. mkumbwa, s. s. 2012. cereal food commodities in eastern africa: consumption production gap trends and projection, muniche. mulugeta, m., tiruneh, g. and alemu, z. a. 2018. magnitude and associated factors of household food insecurity in fedis woreda east hararghe zone , oromia region , ethiopia. agric. food secur., 1–8. available at: https://doi.org/10.1186/s40066-0170140-6. piguet, f. 2003. hararghe food security hampered by long-term drought conditions and economic constraints. un rep., 1–14. rashid, s. 2010. staple food prices in ethiopia, addis ababa, ethiopia. sidhu, j. s., kabir, y., huffman, f.g., sidhu, j.s. and kabir, y. 2007. functional foods from cereal grains. int. j. food prop., 2912. uehara, m. 2012. food diversification in japan : recent developments in. j. issaas, 18: 22–30. east african journal of sciences (2018) volume 12 (1) 61-76 _____________________________________________________________ licensed under a creative commons *corresponding author. e-mail: alemunega531@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2018 issn 1993-8195 (online), issn 1992-0407(print) reaction of improved maize (zea mays l.) varieties to grey leaf spot (cercospora zeaemaydis) in south and southwest ethiopia alemu nega*, fikre lemessa, and gezahegn berecha department of horticulture and plant sciences, college of agriculture and veterinary medicine, jimma university, p. o. box 307, jimma, ethiopia. abstract: grey leaf spot (gls) is one of the most important diseases that constrain maize production and productivity in maize-growing areas of ethiopia where a warm humid environmental condition prevails. thus, this study was conducted to evaluate the reaction of 12 maize varieties to maize grey leaf spot under field conditions in hawassa and jimma, south and southwest ethiopia, in 2014 and 2015 cropping seasons. the treatments consisted of twelve maize varieties. the experiment was laid out as a randomized complete block design (rcbd) and replicated three times per treatment. disease severity was assessed as the proportion of leaf area affected by the disease on 10 randomly tagged plants in the middle two rows. the area under disease progress curve (audpc) and disease progress rates were estimated from the percent severity index (psi). similarly, grain yield was determined after harvest and converted into yield per hectare. the results revealed that the final disease severity varied from 37.33 to 84.83 psi and 39.5 to 81.83 psi at jimma; 35.67 to 78.12 psi and 35.67 to 78.12 psi at hawassa in 2014 and 2015 main cropping seasons, respectively. audpc varied from 1426.67 to 3281.67%-days in jimma and from 1476.67 to 3225%-days in hawassa in 2014 main cropping season; 1176.17 to 3031.67%-days in jimma and 1226.67 to 2975%-days in hawassa in 2015 main cropping season. the varieties gibe-2, bh-543 and local-k exhibited high disease severity, high audpc and high infection rate and were categorized as highly susceptible maize varieties. the results also indicated that bh-660 and bh-670 were considered resistant to grey leaf spot across the two locations and had low disease severity as well as low audpc values. it is concluded that under field conditions, different maize varieties responded differently to grey leaf spot and the disease severity was strongly affected by the use of different resistance levels of maize varieties and difference in the environmental conditions. it is therefore, promising to use the two maize varieties, such as bh-660 and bh-670, were considered as resistant under field conditions and that are recommended to be used by farmers in the study areas and elsewhere with similar agro-ecologies in ethiopia. keywords: audpc, disease progress rate, disease severity index, grey leaf spot, grain yield, zea mays. 1. introduction maize (zea mays l.) is one of the most important food crops world-wide. it is the principal component of human diet and feed constituent for domestic animals. it ranks third in production worldwide following wheat and rice (faostat, 2012), and is grown in most parts of the world over a wide range of environmental conditions, with altitudinal ranges from 0 to 3000 m above sea level (dowswell et al., 1996). in africa, maize is grown by small and medium-scale farmers who cultivate 10 hectares or less (devries and toenniessen, 2001). in the region, the use of agricultural input is extremely low resulting in poor average yield of 1.3 tons per hectare (bänziger and diallo, 2004). regardless of poor or low productivity, maize production area is rapidly increasing in sub-saharan africa, including the marginal areas (faostat, 2012). in ethiopia, maize is one of the most important cereal crops grown. among all cereals, maize ranks second to tef (eragrostis tef) in area coverage but first in productivity and total production (csa, 2014). maize is currently produced by more farmers than any other crops. at the national level, there are about 8.8 million maize cropping smallholder farmers in ethiopia (csa, 2012). in view of its importance, extensive adaptation, total production and productivity, maize is considered as one of the most priority food security crops in ethiopia (csa, 2012). however, maize yields have remained low due to several biotic, abiotic and socioeconomic constraints (mosisa et al., 2012). the predominant biotic constraints of maize production in ethiopia are (diseases, weeds, insect insects and other arthropod pests), abiotic (drought and nutrient deficiencies) and socio-economic (market price fluctuation, and unavailability of inputs) constraints that limit maize productivity in ethiopia (tesfa et al., 2004; mosisa et al., 2012). among the biotic factors, diseases are the principal threats limiting maize production and productivity. foliar diseases, including grey leaf spot (cercospora zeae-maydis tehon and mailto:alemunega531@gmail.com alemu et al. east african journal of sciences volume 12 (1) 61-76 62 daniels), turcicum leaf blight (exserohilum turcicum pass leonard and suggs) and common leaf rust (puccinia sorghi schr.) (tewabech et al., 2012) are the most important infectious diseases of maize in the country. compared to other leaf diseases, grey leaf spot is the most widely distributed and has high economic importance (tewabech et al., 2012). grey leaf spot is particularly important in africa because maize is the main staple food crop for millions of people in the rural areas (ward et al., 1999). this foliar disease has the potential to threaten food security in many countries (ward et al., 1999). the disease causes necrotic lesions that may coalesce and cause extensive blighting of leaves, thereby reducing the photosynthetic area of maize plants. consequently, it may result in poor grain filling, which leads to low maize yields (kinyua et al., 2010) that impacts the yield. according to allison and watson (1996), the upper eight or nine leaves of the plant contribute 75 to 90% of the photosynthate for grain filling. the premature death of these tissues due to infection seriously restricts accumulation of photosynthates in the developing kernel. in years of severe blighting, susceptible hybrids develop symptoms that look like frost damage due to necrosis of leaf area (donahue et al., 1991). because of reduced photosynthetic areas resulting from blighting, photosynthate is derived from the stalk and roots at a greater than normal level causing them to senesce prematurely. among the major disease constraints on maize production in ethiopia, diseases such as grey leaf spot result in high yield losses due to high grey leaf spot incidence and severity in the farmers’ fields. cultural methods and use of fungicides have been used for grey leaf spot management (ward et al., 1997), but have not been effective because fungicide application is costly and not practical in most operations for the resourcepoor farmers and also unpredictable weather and the environmental side effects (danson et al., 2008). availability and adoption of resistant maize hybrids would provide a cost-effective means of controlling grey leaf spot (ininda et al., 2007). however, little empirical information is available regarding the reaction of several maize varieties to the disease. therefore, the objective of this study was to evaluate the reaction of improved maize varieties to maize grey leaf spot under field conditions. 2. materials and methods 2.1. description of the experimental sites the grey leaf spot evaluation of field trials was made on 12 maize varieties planted at two locations in 2014 and 2015 main cropping seasons. field experiments were conducted at two different locations of south and southwest ethiopia, namely eladale (experimental field of jimma university college of agriculture and veterinary medicine) and hawassa agricultural research center (harc) in the two consecutive main rainy seasons. the field experiment was conducted on clay soil at eladale and clay loam soil at hawassa agricultural research center (harc) during the main cropping seasons. jimma (eladale-jucavm field) is located at 7o42’n and 36o48’e with an altitude of 1813 m.a.s.l. in southwest jimma zone at around 8 km away from jimma university college of agriculture and veterinary medicine (jucavm). jimma (eladalejucavm field) is also characterized by extended higher precipitation (estimated to exceed 1616 mm per annum) and many rainy days than hawassa during the cropping periods with mean daily temperatures ranging between 12.4 and 28.4oc (mulugeta et al., 2011), while hawassa agricultural research center (harc) is located at 7o4’n and 38o31’e with an altitude of 1700 m.a.s.l. in southern nations, nationalities and peoples’ region (snnpr). the mean annual rainfall for the location is 1072 mm during the main cropping season with mean minimum and maximum temperatures of 14.1 and 26.3oc, respectively (waga, 2011). 2.2. land preparation, experimental materials, treatments and design: 2.2.1. land preparation the land was prepared by plowing two times in each cropping season. recommended fertilizers dap and urea at a rate of 100 kg ha-1 each was applied. it was performed by applying dap at the time of planting and urea was applied when the maize plants reached at knee height. cultivation and weed management were carried out three times after planting at the two locations of jimma and hawassa in 2014 and 2015 main cropping seasons. 2.2.2. experimental materials eleven released maize varieties (bh-660, bh-540, bh140, bh-543, bhqpy-545*, bh-670, bh-661, gibe-2, morka, kuleni, and gibe-1) with different levels of resistance and one local check variety, totally 12 maize varieties, were evaluated for their reaction to grey leaf spot at two locations (jimma and hawassa) in 2014 and 2015 main cropping seasons (table 1). 2.2.3. treatments and experimental design the treatments consisted of twelve maize varieties tested at two locations of jimma and hawassa in 2014 and 2015 cropping seasons. the experiments were conducted under naturally-infected fields. each plot size was 3 m x 3 m (= 9 m2) consisting of four rows with 30 cm intra-row and 75 cm inter-row spacing’s. the whole plots were bordered on four sides with three infector rows of the susceptible variety, local-k. the space between plots was 1 m and there was 1.5 m space between blocks. the total area of the land used for this experiment was 16 m x 51 m (816 m2). seeds were planted in rows with two seeds per hill and also alemu et al. reaction of improved maize varieties to grey leaf spot under field 63 seedlings were thinned into one plant per hill four weeks after emergence. in each plot 40 plants were grown and each row had 10 maize plants. the treatments were arranged in a randomized complete block design (rcbd) with three replications. sowing was done on april 19 and april 28 in 2014 and 2015 cropping seasons at jimma and april 27 and may 18 in 2014 and 2015 cropping seasons at hawassa, respectively. table 1. description of maize varieties with their agro-ecological adaptation and agronomic characters used in this study at jimma and hawassa, south and southwest ethiopia. varieties year of release altitude (m) rainfall (mm) plant height (cm) reaction to gls released by bh-660 1993 1600-2200 1000-1500 255-290 t barc bh-540 1995 1000-2000 1000-1200 240-260 mt barc bh-140 1988 1000-1700 1000-1200 240-255 mt barc bh-543 2005 1000-2000 1000-1200 250-270 mt barc bhqpy-545* 2008 1000-1800 1000-1200 250-260 t barc bh-670 2001 1700-2400 1000-1500 260-295 t barc bh-661 barc gibe-2 2011 barc morka 2008 1600-1800 1200-2000 270-300 t jarc kuleni 1995 1700-2200 1000-1200 240-265 t barc gibe-1 2000 1000-1700 1000-1200 240-260 mt barc local-k s note: t = tolerant; mt = moderately tolerant; s = susceptible; where: barc = bako agricultural research center, jarc = jimma agricultural research center. source: mandefro et al. (2009). 2.3. disease incidence and severity assessments field disease assessment at each location was assessed 6 times throughout the growing season from onset of the disease until the maize reached the dent stage (ringer and grybauskas, 1995). ten randomly taken plants in the two central rows were tagged and used for successive disease assessments. disease incidence (%): the progress of percentage incidence of disease in maize was quantified in staggered plant at 10 days intervals starting from onset of disease to dent stages or ratio of infected leaves to the total number of leaves on a particular plant and expressed as a percentage. the percentages of disease incidence were calculated by using the following formula suggested by cooke et al. (2006). incidence (%) = no. of diseased plants x100 (1) total no of plants assessed disease severity (%): disease severity was rated using 1-5 scales described by maroof et al. (1993). the scores were described as 1 = no symptoms; 2 = moderate lesion development below the leaf subtending the ear; 3 = heavy lesion development on and below the leaf subtending the ear with a few lesions above it; 4 = severe lesion development on all but the uppermost leaves, which may have a few lesions; and 5 = all leaves dead. rating started when obvious genotypic differences for gls reaction became apparent and continued until leaves senesced. disease severity scores were converted into percentage severity index (psi) for analysis using the following formula suggested by wheeler (1969) as given below. psi= sum of all numerical ratings x 100_________ (2) total no. of rated x max. disease score on scale 2.4. area under disease progress curve (audpc) the area under disease progress curve, which consists of proportions of diseased plants, was calculated from disease severity recorded at ten days interval starting from the onset of disease 6 times in each location throughout the growing period and converted to percent severity index (psi). to ensure consistent disease evaluation in the field, the area under disease progress curve was calculated. this curve was developed from 10 days disease severity reading in different locations. by constructing a curve, symptom development and disease severities were compared over years and locations. the area under disease progress curve (audpc) is used to quantify suppressing of the beginning of the epidemic and the time until the grey leaf spot reached peak. grey leaf spot (gls) for the whole plant was converted to audpc to compare relative level of resistance and susceptible varieties. area under disease progress curve (audpc) was computed from severity data using the formula suggested by campbell and madden (1990) as: n audpc = ∑ [0.5 (xi +xi+1)] [ti+1 ti] (3) i=1 alemu et al. east african journal of sciences volume 12 (1) 61-76 64 where: xi is the disease severity expressed in percentage at ith observation, ti is time (days after planting) at the ith observation and n is total number of days disease was assessed. 2.5. phenological parameters plant height (cm): plant height was measured in centimeters two weeks after pollen shed had ceased, as the distance from the soil surface to the base of lowest tassel branch of 10 plants in the middle two rows. days to physiological maturity: days to maturity of 10 plants from the two middle rows of each plot were recorded as the number of days from emergence to when 50% of the plants in a plot formed a black layer at the tip of each kernel on the ears. 2.6. grain yield (gy) and thousand seed weight grain yield (kg ha-1): at maturity, the yields of the 10 maize varieties were harvested manually from the two middle rows of each plot. the yield from the two rows was converted into kg per hectare (kg ha-1). thousand seed weight (tsw) (g): one thousand randomly taken seeds from each plot were weighed separately and thousand seed weight was reported in grams. 2.7. data analysis analysis of variance (anova) was conducted for gls severity, audpc and infection rate at all plant growth stages, and yield data were subjected to analysis of variance, and means were compared using least significant difference (lsd) at p≤0.05 level of significance and sas version 9.2 (sas, 2008) software was employed for the analysis. to determine the disease progress rate, a logistic growth model, ln[x/ (1x)], (vander plank, 1963) was used to estimate the disease progression. the transformed data were regressed over time (dap) to determine the disease progress rate. the audpc values and disease progress rate (r) were calculated for each tested variety and data were analyzed by analyses of variance. the disease progress rates (r) were calculated based on the linearized logistic model (vander plank, 1963) and the calculated values were analyzed by using sas version 9.2 as follows: (4) where: r = disease progress rate, xo = initial disease severity, x = final disease severity, t = the duration of the epidemic and ln = natural logarithm. the two locations were considered as different environments because of heterogeneity of variance as tested bartlett’s test (gomez and gomez, 1984) and f-test was significant for grey leaf spot reaction on maize varieties under field conditions studied. thus, the data were not combined for analyses. correlation analysis was performed using sas version 9.2 to determine relationship among disease assessment parameters, such as disease severity, area under disease progress curve (audpc) and infection rate (r) and yield and thousand seed weight. 3. results 3.1. disease development on maize varieties under field conditions 3.1.1. grey leaf spot (gls) severity typical grey leaf spot (gls) symptoms appeared on the highly susceptible variety earlier than on the improved maize varieties at both locations in 2014 and 2015 cropping seasons. different levels of grey leaf spot severities (as percent leaf area diseased) were recorded on the different maize varieties tested under natural infections. the mean disease severity in the two cropping seasons significantly (p < 0.05) differeed among the tested varieties. the varieties more or less showed differential responses to the disease. the mean initial and final disease severity in the two cropping seasons were significantly (p < 0.05) different among the varieties in both locations (tables 2 and 3). the lowest mean initial and final disease severity was recorded for both improved and susceptible maize varieties at both locations in 2014 and 2015 cropping seasons. disease severity during initial assessment varied significantly (p ≤ 0.05) among the varieties in two seasons of testing at jimma. higher initial severities of 24.5 psi on the variety bh-543 and 28.12 psi on the susceptible check variety, local-k, were recorded in 2014 and 2015 cropping seasons at jimma, respectively, while it was much lower on varieties bh660 (11.33 psi), bh-670 (12.67 psi), kuleni (12.67 psi) and bh-540 (13.67 psi) in 2014 and bh-660 (12 psi), bh-670 (13.67 psi), kuleni (15.5 psi) and morka (16.12 psi) in 2015 cropping season at jimma. however, there was no significant difference between the four varieties in initial disease severity in 2014; and also there was no significant difference among the three varieties in initial disease severity in 2015 at jimma. the susceptible check variety, local-k, had no significant difference from six of the varieties other than bh-670, bh-660, kuleni, bh-140, bh 540, and morka in initial disease severity in 2014, and local-k had also no significant difference from any one of the varieties other than bh-543 in initial disease severity in 2015 at jimma (tables 2 and 3). the level of initial disease severity on the variety bh-543 was 24.5 psi, which was even higher than the susceptible check local-k in 2014 and lower than the susceptible check variety, local-k, at jimma, in 2015. disease severity at final assessment near crop physiological maturity was also significantly (p ≤ 0.05) different among the varieties in 2014 and 2015 at jimma. lower final disease severities of 37.33 and 39.5 alemu et al. reaction of improved maize varieties to grey leaf spot under field 65 psi were recorded on the variety bh-660 in two cropping seasons (2014 and 2015) and the variety bh670, which had 49.12 psi and 44 psi final disease severity at jimma in two seasons of testing, respectively (table 3). the levels of final disease severities on the varieties bh-660 and bh-670 were significantly different from that of the other remaining tested varieties; these varieties showed similar reaction at their early growth stages in having significantly lower initial gls severities. the initial disease severity on the variety bh-670 was slightly higher (13.67psi) than bh660 (12 psi), and was significantly different from the susceptible check, local-k, (28.12 psi) at jimma in two seasons of testing. at hawassa, grey leaf spot severity during initial assessment varied significantly (p < 0.05) among the varieties (table 3). higher initial severities of 25.67 psi and 25.26 psi were recorded on the susceptible check variety, local-k, while it was much lower with values of 10.67 psi and 10.33 psi on the variety (bh-660), 11.67 psi and 12 psi on the variety bh-670, 12 psi and 13.5 psi on the variety (kuleni), and 14 psi and 16.33 psi on the variety bh-140 at hawassa, in 2014 and 2015 cropping seasons, respectively. however, there was no significant difference between the four varieties (bh-140, bh-540, bh-670 and kuleni) in initial disease severity in 2014 and, also, there was no significant difference among the three varieties (bh140, bhqpy*-545 and morka) in initial disease severity at hawassa in 2015 cropping season. the susceptible check variety, local-k, had significant difference from all of the rest varieties except bh-543 in initial disease severity (table 3). disease severity at final assessment near crop physiological maturity was also significantly (p < 0.05) different among the 12 varieties in the two cropping seasons at hawassa. lower final disease severity 38.33 psi and 35.67 psi was recorded on varieties bh-660 and bh-670, which had 50 psi and 43 psi final disease severity in 2014 and 2015 cropping seasons, respectively (tables 2 and 3). the levels of final disease severity on bh-660 and bh-670 were significantly different from that of the other varieties tested; these varieties showed more or less similar reaction at their early growth stages in having significantly lower initial severity of the disease. the initial disease severity on the bh-670 variety was also somewhat higher than bh-660, and was significantly different from the susceptible check, local-k, at hawassa in 2014 and 2015. 3.1.2. disease progress rates disease progress rates and parameter estimates due to grey leaf spot are tabulated hereunder (tables 2 and 3). the disease progress rates showed variations among the 12 maize varieties used in both locations in 2014 and 2015 cropping seasons. disease progress rates calculated in the 12 maize varieties ranged from 0.0256 to 0.0489 units’ day-1 and 0.02613 to 0.04340 units day-1 at jimma in 2014 and 2015, respectively (table 2 and 3). at hawassa, the rates were in between 0.0273 to 0.0561 units day-1 and 0.0262 to 0.0407 unit day-1 in 2014 and 2015 cropping seasons, respectively. the disease progress rate was relatively higher at jimma than at hawassa in 2015 cropping season, while the disease progress rate was also lower at jimma than at hawassa in 2014 cropping season. on the varieties bh-540, bh-543, local-k, bh-661, gibe-1, gibe-2 and bh-140 at both locations, the disease progressed faster than in the other five varieties in 2014, whereas in 2015 on the varieties bh-140, local-k, bh-543, bh-661, gibe-1 and gibe-2 in both locations, the disease progressed faster than in the other six varieties. the calculated disease progress rates were significantly different among the maize varieties tested. even though the maximum audpc was observed on localk, relatively faster mean disease progress rates, i.e. r = 0.0561 and r = 0.0407, over the years was observed on the varietiesbh-540 and bh-140 at hawassa in 2014 and 2015, respectively. on the other hand, the maximum audpc was observed on local-k; however, faster mean disease progress (infection) rate, r = 0.04340 over the seasons was observed on the variety bh-540 at jimma in 2015. the overall mean infection rate on bh-540 and bh-140 was higher than that of the rates on bh-670, bh-660, kuleni and morka in both locations (tables 2 and 3). disease progress rates of 0.025 and 0.031 units day-1 were observed on the varieties bh-660 and bh-670, while the rates were 0.027 and 0.033 units day-1 on the varieties bh-660 and bh-670, respectively, although there was significant difference between infection rates on bh-660 and bh670 as well as kuleni at jimma, while no significant difference was observed at hawassa in 2014 cropping season. alemu et al. east african journal of sciences volume 12 (1) 61-76 66 table 2. mean initial (psii) and final (psif) severity indices and parameter estimates of grey leaf spot (c. zeae-maydis) on 12 maize varieties at jimma and hawassa in 2014 main cropping seasons. varieties jimma in 2014 hawssa in 2014 psiintial psifinal disease progress rate (logit days-1) psiintial psifinal disease progress rate (logit days-1) local-k 23.00+1.73ab 84.83+1.44a 0.0489+0.0018a 25.67+0.52a 84.00+0.89a 0.0453+0.0007bc bh-543 24.50+0.50a 80.00+2.29ab 0.0419+0.0028cd 22.33+0.51b 83.67+2.06a 0.0481+0.0022b gibe-2 21.00+2.00bc 79.25+2.16bc 0.0445+0.0024bc 19.00+0.89c 82.12+2.46a 0.0497+0.0036b bh-140 17.00+2.64d 71.50+6.26de 0.0421+0.0036cd 14.00+2.36d 75.33+1.36bc 0.0490+0.0019b bh-540 13.67+2.31e 74.00+3.60cd 0.0484+0.0010ab 12.00+1.55de 79.67+1.36ab 0.0561+0.0031a gibe-1 22.33+0.57a-c 78.00+0.86bc 0.0418+0.0012cd 20.33+0.51bc 81.00+1.54a 0.0469+0.0020b bh-661 20.33+0.57bc 75.33+1.57b-d 0.0413+0.0008cd 19.00+0.89c 82.33+1.86a 0.0499+0.0028b bhqpy*-545 21.00+1.00bc 74.33+2.52cd 0.0399+0.0019de 18.67+1.36c 72.33+2.25cd 0.0406+0.0031cd kuleni 12.67+1.53e 55.50+1.50f 0.0359+0.0028ef 12.00+0.89de 49.00+4.47e 0.0325+0.0026fg morka 19.60+2.94cd 66.50+3.96e 0.0351+0.0042fg 18.00+2.36c 68.00+4.73d 0.0380+0.0048de bh-670 12.67+1.53e 49.12+1.75g 0.0317+0.0017g 11.67+1.03de 50.00+2.25e 0.0335+0.0009ef bh-660 11.33+1.53e 37.33+4.85h 0.0256+0.0033h 10.67+1.03e 38.33+4.50f 0.0273+0.0034g cv (%) 9.83 4.51 6.25 8.56 4.35 7.35 lsd(0.05) 3.04 5.25 0.0042 2.45 5.19 0.0054 note: mean within a column followed by the same letters are not significantly different from each other according to lsd at 5% probability level. lsd = least significant difference, cv = coefficient of variation. initial and final disease severity (psi) of grey leaf spot. table 3. mean initial (psii) and final (psif) severity indices and parameter estimates of grey leaf spot (c. zeae-maydis) on 12 maize varieties at jimma and hawassa in 2015 main cropping seasons. varieties jimma in 2015 hawassa in 2015 psiintial psifinal disease progress rate (logit days-1) psiintial psifinal disease progress rate (logit days-1) local-k 28.12+3.40a 81.83+1.44a 0.0407+0.0036ab 25.26+1.10a 78.12+0.78a 0.0393+0.0012ab bh-543 26.67+2.00ab 78.33+4.31ab 0.0385+0.0015b 23.67+2.00ab 74.83+0.76ab 0.0377+0.0025b gibe-2 24.12+0.76b 76.25+2.16bc 0.0385+0.0034ab 21.16+0.76cd 73.08+3.76b 0.0386+0.0026ab bh-140 18.67+1.53cd 70.00+1.73d 0.0387+0.0030ab 16.33+1.15g 69.12+0.28c 0.0407+0.0013a bh-540 19.50+0.87c 73.67+0.57cd 0.0434+0.0019a 19.00+2.64de 67.83+2.75c 0.0367+0.0039bc gibe-1 24.50+2.78b 75.00+0.86bc 0.0371+0.0025b 21.50+2.78bc 71.50+3.50bc 0.0370+0.0023b bh-661 19.83+0.76c 73.67+1.52cd 0.0404+0.0018ab 18.83+1.26ef 55.12+1.61e 0.0278+0.0023e bhqpy*-545 18.42+0.80c-e 73.33+2.08cd 0.0417+0.0024ab 16.75+1.14fg 60.50+1.32d 0.0338+0.0018cd kuleni 15.50+0.50ef 52.50+1.50f 0.0299+0.0004cd 13.50+0.50hi 46.83+1.04f 0.0288+0.0002e morka 16.12+2.36def 56.83+4.36e 0.0321+0.0051c 14.92+0.72gh 56.12+3.88e 0.0332+0.0034d bh-670 13.67+0.28fg 44.00+4.27g 0.0267+0.0028d 12.00+0.00ij 43.00+1.00g 0.0285+0.0006e bh-660 12.00+1.00g 39.50+1.00h 0.0261+0.0020d 10.33+0.57j 35.67+2.08h 0.0262+0.0005e cv (%) 9.37 3.83 8.02 7.44 3.57 5.11 lsd(0.05) 3.14 4.29 0.0049 2.24 3.69 0.0029 note: means within a column followed by the same letters are not significantly different from each other according to lsd at 5% probability level. lsd = least significant difference, cv = coefficient of variation. initial and final disease severity (psi) of grey leaf spot. alemu et al. reaction of improved maize varieties to grey leaf spot under field 67 3.1.3. area under disease progress curve (audpc) audpc was computed from severity data and showed highly significant (p < 0.01) difference among the tested 12 maize varieties at both locations in 2014 cropping season (figures 1 and 2). in 2014 cropping season, audpc varied between 1426.67 and 3281.67%-days in jimma, whereas the audpc values varied between 1476.67 and 3225%-days in hawassa. the highest (3281.67%-days) audpc value was calculated for the local-k, which is considered as a more susceptible variety in jimma, while 3225%-day was calculated for the same local-k in hawassa. since the lowest audpc value was calculated for the variety bh-660, followed by bh-670 and kuleni varieties, these varieties are considered as resistant to gls at both locations in the two testing seasons (figures 1 and 2). there was also highly significant (p < 0.01) difference in audpc values computed from severity data among the tested 12 maize varieties at both locations in 2015 cropping seasons (figures 3 and 4). in 2015 year, audpc values varied between 1176.17and 3031.67%days at jimma, whereas the audpc values varied between 1226.67 and 2875%-days in hawassa. the highest (3031.67%-days) audpc value was calculated for the local-k that was considered as a more susceptible variety at jimma than at hawassa, while 2975%-days were calculated for the local-k at hawassa. since the lowest audpc value was calculated for bh-660, followed by the varieties bh670 and kuleni, they were considered as resistant to the disease at the two locations in the two testing seasons. all varieties that were considered as susceptible resulted in consistently higher area under disease progress curve at jimma than at hawassa during the two testing seasons. the result of this analysis in line with those data obtained from different similar assessment. overall, results of the two season experiments indicated a difference but stable reaction by the varieties to natural infection by grey leaf spot at hawassa (south ethiopia) and jimma (southwest ethiopia). figure 1. audpc values for maize grey leaf spot on 12 maize varieties tested in 2014 cropping season in jimma, southwestern ethiopia. figure 2. audpc values of grey leaf spot on 12 maize varieties tested in 2014 cropping season in hawassa, south ethiopia. figure 3. audpc values of maize grey leaf spot on 12 maize varieties tested in 2015 cropping season in jimma, southwestern ethiopia. figure 4. audpc values of maize grey leaf spot on twelve maize varieties tested in 2015 cropping season in hawassa, southern ethiopia. 3.1.4. disease progress curve disease onset (do) of grey leaf spot appeared at jimma and hawassa early at 50 and 52 days after planting, respectively, in 2014 cropping seasons. however, disease appearance at jimma and hawassa also appeared at 54 and 60 days after planting, respectively, in 2015 cropping season. the dry weather at hawassa at planting time most probably delayed the onset of grey leaf spot there (data was not shown). the disease progress curve of grey leaf spot was sketched coherently for 12 maize varieties tested at both locations (figures 5 – 8). each curve for 12 maize varieties revealed that disease severity progressed increasingly starting from the onset to the final severity records at both locations during the study periods. the four disease progress curves for 12 maize varieties tested also indicated that the disease progress alemu et al. east african journal of sciences volume 12 (1) 61-76 68 was not similar for all improved and susceptible check maize varieties used. disease severity in local-k, bh543, gibe-1 and gibe-2 followed relatively high progressive curve trends and displayed the highest levels of grey leaf spot severity in the two cropping seasons at jimma. disease severity in bh-540, bh-140, bh-661 and bhqpy*-545 followed roughly similar curves and lied at intermediate levels of grey leaf spot severity, whereas disease progress curves of bh-660, bh-670, kuleni and morka displayed the lowest levels of grey leaf spot severity at jimma at different days after planting in the two testing seasons (figures 5 and 7). on the other hand, disease development also differed markedly among maize varieties at hawassa. disease severity in local-k, bh-543, gibe-1, and gibe-2 followed relatively high progressive curve and displayed the highest levels of grey leaf spot severity. disease severity in bh-540, bh-140, bh-661, bhqpy*-545 and morka followed medium curves and lied intermediate levels of grey leaf spot severity while the varieties bh-660, bh-670 and kuleni had low levels of grey leaf spot infection at hawassa at different days after planting in 2014 and 2015 cropping seasons (figures 6 and 8). figure 5. disease progress curve on 12 maize varieties at jimma in 2014 main cropping season. figure 6. disease progress curve on 12 maize varieties at hawassa in 2014 main cropping season. figure 7. disease progress curve on 12 maize varieties at jimma in 2015 main cropping season. figure 8. disease progress curve on 12 maize varieties at hawassa in 2015 main cropping season. 3.2. phenological parameters the phenological parameters of all tested maize varieties showed a highly significant (p < 0.01) difference among each other at the two locations in 2014 cropping season (table 4). the tallest plant heights of 333.3 and 254.33 cm were measured from the variety morka from the two experimental sites of jimma and hawassa, while gibe-2 with plant heights of 192 and 205.67 cm was the shortest variety at jimma and hawassa, respectively, measured in 2014 cropping season. there was also highly significant (p < 0.01) difference in plant height measured among the tested 12 maize varieties at the two locations in 2015 cropping season (table 5). the plant heights of all tested maize varieties showed taller appearance at jimma than at hawassa in both 2014 and 2015 cropping seasons. the tallest appearance of tested maize varieties at jimma was due to the prolonged growing season and effect of weather. the prolonged season may lead to delay in maturity and increase in vegetative growth of the maize varieties. at jimma, the variety local-k was the latest and the earliest in maturity was bh-660, while at hawassa the variety local-k was the latest and the earliest in maturity was bh-660 in the two testing seasons alemu et al. reaction of improved maize varieties to grey leaf spot under field 69 table 4. plant height and days to physiological maturity of 12 maize varieties in jimma (southwest ethiopia) and hawassa (south ethiopia) in 2014 main cropping season. varieties jimma in 2014 hawassa in 2014 plant height (cm) days to maturity plant height (cm) days to maturity bh-140 198.90+11.56f-h 147.67+2.25fg 237.67+5.86a-d 148.00+1.78d bh-540 218.90+17.13d-f 149.67+2.25fg 229.33+5.03a-d 146.00+1.78d bh-543 229.70+15.82c-e 150.33+2.25f 212.67+8.62cd 148.33+6.77d bh-660 241.06+3.94b-d 145.00+2.68g 251.67+10.21ab 144.33+2.25d bh-661 250.40+10.14bc 161.67+3.14c 233.33+7.76a-d 158.00+1.78c bh-670 257.40+16.05b 161.00+3.22d 256.00+2.64a 157.00+1.78c bhqpy*-545 195.50+14.23gh 167.67+2.25c 236.33+6.43a-d 165.33+2.25b gibe 1 215.67+11.58e-g 148.00+2.68fg 228.00+5.00a-d 145.33+2.25d gibe 2 191.76+15.33h 162.33+1.86d 205.67+33.65d 160.00+2.68bc kuleni 221.80+4.39de 155.00+2.68e 216.00+36.29b-d 150.00+2.68d local-k 256.13+2.01b 195.00+2.68a 210.33+37.63cd 183.67+2.25a morka 333.27+22.46a 181.00+2.36b 245.33+30.17a-c 179.33+2.73a cv (%) 5.17 1.60 8.27 2.14 lsd(0.05) 20.51 4.32 32.25 5.68 note: mean within a column followed by the same letters are not significantly different from each other according to lsd at 5% probability level. cv = coefficient of variation, lsd = least significant difference. table 5. plant height and days to physiological maturity of 12 maize varieties in jimma (southwest ethiopia) and hawassa (south ethiopia) in 2015 cropping season. varieties jimma in 2015 hawassa in 2015 plant height (cm) day to maturity plant height (cm) day to maturity bh-140 204.90+12.92e-f 145.67+2.52g 232.67+5.86a-c 151.00+2.00d bh-540 224.90+19.15de 147.67+2.52f 224.33+5.03a-c 149.00+2.00d bh-543 235.70+17.68cd 148.33+2.52f 207.67+8.62bc 151.33+7.57d bh-660 201.50+15.91fg 143.00+3.00g 205.33+37.63c 147.33+2.51d bh-661 247.07+4.41bc 159.67+3.51d 228.33+7.76a-c 161.00+2.00c bh-670 256.40+11.34b 159.00+3.60d 231.33+6.43a-c 160.00+2.00c bhqpy*-545 263.40+17.94b 165.67+2.52c 246.67+10.21a 168.33+2.51bc gibe 1 221.67+12.95d-f 146.00+3.00fg 223.00+5.00a-c 148.33+2.51d gibe 2 197.76+17.14g 160.33+2.08c 200.67+33.65c 163.00+3.00bc kuleni 227.80+4.91cd 153.00+3.00e 211.00+36.29b-c 153.00+3.00d local-k 262.40+2.25b 193.00+3.00a 251.00+2.64a 186.67+2.51a morka 339.27+25.12a 179.00+2.64b 240.33+30.17ab 182.33+3.05a cv (%) 5.04 1.61 8.46 2.09 lsd(0.05) 20.51 4.32 32.25 5.68 note: mean within a column followed by the same letters are not significantly different from each other according to lsd at 5% probability level. cv = coefficient of variation, lsd = least significant difference. 3.3. grain yield (gy) and thousand seed weight grain yield showed a highly significant (p ≤ 0.01) difference among the 12 tested maize varieties in both locations in 2014 cropping season (table 6). at hawassa, the mean grain yield and thousand seed weight were significantly (p < 0.05) greater than that of jimma when mean disease severity was significantly (p < 0.05) lower in the 2014 main cropping season. this was because the disease at jimma started early and the growth stage of the crop was followed by very fast disease progress before the crop reached dent or physiological maturity stage, whereas at hawassa highest grain yield and thousand seed weight were obtained in the two main cropping seasons since the disease symptoms were observed later and the development of the disease was slow and reached maximum when the crop reached maturity stage. therefore, the disease effect on grain yield was relatively higher in jimma than in hawassa during 2014 cropping season. the lowest grain yield and thousand seed weight (tsw) (3514.7 kg ha-1, 367.77 g), (3570.2 kg ha-1, 371.46 g) and (4018 kg ha-1, 312.87 g) was measured on bh-543, gibe-2 and local-k maize varieties, respectively, at jimma in 2014 cropping season, whereas at hawassa lowest grain yield and thousand seed weight (5101.9 kg ha-1, 1552.33 g), (5393.2 kg ha-1, 1530.62 g) and (5412.9 kg ha-1, 1401.67 g) was alemu et al. east african journal of sciences volume 12 (1) 61-76 70 measured on local-k, gibe-2 and bh-543, respectively, in 2014 main cropping season. grain yields of the relative susceptible varieties bh-543, gibe-2 and local-k were generally lower in jimma than in hawassa in both 2014 and 2015 main cropping seasons. both bh-543 and gibe-2 were previously released as moderately resistant varieties to the disease. but, in the present study they were considered as susceptible varieties with the lowest grain yield in the two locations. the highest grain yields of 5791.8 kg ha-1, 5750.9 kg ha-1, 5620.6 kg ha-1 and 5612.7 kg ha-1 along with thousand seed weights of (455.83 g, 412.13 g, 406.93 g and 429.57 g were obtained from bh-660, bh-670, kuleni and morka maize varieties, respectively, at jimma in 2014 cropping season, while at hawassa, the highest grain yields and the corresponding thousand seed weights (7284.8 kg ha-1, 1672.67 g), (7100 kg ha-1, 1605.67 g), (6234.6 kg ha-1, 1572.33 g) and (5787.1 kg ha-1, 1578.33 g) were recorded on bh-660, bh-670, morka and kuleni maize varieties, respectively, in 2014 main cropping season. there was also highly significant (p < 0.01) difference in grain yield among the 12 tested maize varieties in both locations (hawassa and jimma) in 2015 cropping season (table 7). at hawassa, the mean grain yield and thousand seed weight was significantly (p<0.05) greater than that of jimma when mean disease severity was significantly (p<0.05) lower in 2015 cropping season, whereas the highest grain yield and thousand seed weight were obtained at hawassa when the disease symptoms were observed later and the development of the disease was slow and reached maximum when the crop reached at maturity stage. therefore, the disease effect on grain yield was also relatively higher at jimma than at hawassa in 2015 testing season. the lowest grain yields along with thousand seed weights (3760.2 kg ha-1, 317.87 g), (3524.7 kg ha-1, 372.77 g) and (4028 kg ha-1, 376.47 g) were measured on bh-543, gibe-2 and local-k maize varieties, respectively, at jimma in 2015 cropping season, whereas lowest grain yields along with thousand seed weights (5383.2 kg ha-1, 1396.67 g), (5402.9 kg ha-1, 1500.33 g) and (5545.9 kg ha-1, 1488.33 g) were measured on bh-543, local-k, and gibe-2, respectively, at hawassa in 2015 cropping season. yields of the relative susceptible varieties bh-543, gibe-2 and local-k were also generally low at jimma than at hawassa in 2014 and 2015 cropping seasons. the highest grain yields along with thousand seed weights (5801.8 kg ha-1, 460.83 g), (5760.9 kg ha-1, 434.57 g), (5630.6 kg ha-1, 411.93 g) and (5099.9 kg ha-1, 410.43 g) were measured on bh-660, bh-670, kuleni and morka maize varieties, respectively, at jimma in 2015 cropping season, while highest grain yields along with thousand seed weights (7274.8 kg ha-1, 1667.67 g), (7090 kg ha-1, 1600.67 g), (6224.6 kg ha-1, 1573.33 g) and (6091.9 kg ha-1, 1568.33 g) were measured on the maize varieties bh-660, bh-670, morka and kuleni, respectively, at hawassa in 2015 cropping season. overall, the grain yield obtained from hawassa experimental site was even higher than that of jimma in the two cropping seasons. therefore, variety reaction to disease severity was affected by locations. this means that a variety that was considered as higher or lower yielder in one location acted differently in other locations, indicating there were differences in the reactions of the varieties across locations. 3.4. correlation analysis among disease variables, yield and phenological parameters relationship among the various grey leaf spot evaluations with grain yield and growth parameters at jimma and hawassa in 2014 and 2015 cropping seasons were determined (table 8). the interactions between parameters were generally the same in both locations. in both sites, all yield component and growth parameters, i.e. thousand seed weight, plant height and days to physiological maturity were positively correlated with grain yield at jimma and negatively correlated with grain yield at hawassa. on the contrary, all the disease parameters were non-significant and were positively correlated with grain yield at jimma and non-significant negatively correlated with grain yield at hawassa. furthermore, disease parameters, i.e. initial and final percent severity indices, area under disease progress curves (audpc) and disease progress rates (r) were highly significant and positively associated with each other in both locations. thousand seed weight, plant height and days to maturity were also non-significant and positively correlated to each other except that plant height was significant and positively associated with both thousand seed weight and days to physiological maturity at jimma, while at hawassa it was nonsignificant and negatively correlated with each other except thousand seed weight that was non-significant and positively associated with both plant heights and days to physiological maturity. generally thousand seed weight was weakly correlated with all parameters at hawassa experimental site and significantly and positively correlated with disease progress rate and plant height at jimma. alemu et al. reaction of improved maize varieties to grey leaf spot under field 71 table 6. grain yields and thousand seed weights of 12 maize varieties tested at jimma (southwest ethiopia) and hawassa (south ethiopia) ethiopia in 2014 cropping season. varieties jimma in 2014 hawassa in 2014 yield (kg ha-1) tsw(g) yield (kg ha-1) tsw (g) bh-140 4189.40+716.08b-d 395.07+51.92bc 5710.20+896.83b 1505.33+48.01ab bh-540 4892.30+278.98a-c 383.67+36.05bc 5778.40+614.86b 1557.33+71.23ab bh-543 3514.70+336.48d 367.77+38.61cd 5412.90+348.62b 1401.67+32.33b bh-660 5791.80+446.08a 455.83+26.84b 7284.80+158.49a 1672.67+92.50a bh-661 4909.60+365.67ab 399.30+35.25a-c 5584.10+1328.72b 1530.33+13.01ab bh-670 5750.90+751.53a 412.13+57.03a-c 7100.00+1098.50a 1605.67+233.35a bhqpy*-545 5093.20+401.24ab 405.43+16.52abc 5723.41+500.72b 1573.33+132.19ab gibe 1 4182.70+260.53b-d 392.87+40.72bc 5555.90+452.57b 1493.33+53.91ab gibe 2 3750.20+712.79d 371.46+26.05bc 5393.20+327.11b 1530.67+13.01ab kuleni 5620.60+763.49a 406.93+10.42a-c 5787.10+917.60b 1578.33+127.75ab local-k 4018.00+422.81cd 312.87+5.95d 6101.90+1315.45ab 1552.33+120.38ab morka 5612.70+656.69a 429.57+49.59bc 6234.60+660.77ab 1572.33+73.00ab cv (%) 12.09 8.73 12.15 6.88 lsd(0.05) 978.27 58.31 1228.9 180.37 note: means within a column followed by the same letters are not significantly different from each other according to lsd at 5% probability level. tsw = thousand seed weight, cv = coefficient of variation, lsd = least significant difference. table 7. grain yields and thousand seed weights of 12 maize varieties tested at jimma (southwest ethiopia) and hawassa (south ethiopia) in 2015 cropping season. varieties jimma in 2015 hawassa in 2015 yield (kg ha-1) tsw(g) yield (kg ha-1) tsw(g) bh-140 4199.40+800.60b-d 404.30+39.41a-c 5700.20+896.83b 1525.33+34.78ab bh-540 4902.90+311.91a-c 400.07+58.04bc 5768.40+614.86b 1567.33+73.00ab bh-543 3760.20+796.93d 317.87+6.65d 5383.20+327.11b 1396.67+32.33b bh-660 5801.82+498.74a 460.83+30.01a 7274.80+158.49a 1667.67+92.50a bh-661 4919.60+408.84a-c 397.87+45.52bc 5574.10+1328.72b 1557.33+71.23ab bh-670 5760.90+840.23a 434.57+55.45ab 7090.00+1098.49a 1600.67+233.35a bhqpy*-545 5622.7+734.21a 417.13+63.75a-c 5777.10+917.60b 1525.67+34.78ab gibe 1 4192.70+291.28b-d 388.67+40.30bc 5713.40+500.72b 1547.00+120.38ab gibe 2 3524.70+376.20d 372.77+43.17cd 5545.90+452.58b 1488.33+53.91ab kuleni 5630.6+853.62a 411.93+11.65a-c 6224.60+660.77ab 1573.33+127.75ab local-k 4028.00+472.72cd 376.47+29.16bc 5402.90+348.62b 1500.33+48.01ab morka 5099.90+453.12ab 410.43+18.47a-c 6091.90+1315.45ab 1568.33+132.19ab cv (%) 12.05 8.62 12.17 6.90 lsd(0.05) 978.52 58.31 1228 180.40 note: mean within a column followed by the same letters are not significantly different from each other according to lsd at 5% probability level. tsw = thousand seed weight, cv = coefficient of variation, lsd = least significant difference. 4. discussion maize is commonly produced by small-scale farmers throughout the world and its production is highly affected by grey leaf spot (gls). because chemical control of grey leaf spot is not practical and economic in maize production areas, adoption of resistant hybrid(s) has been established as a cost-effective means of managing grey leaf spot (ininda et al., 2007). the present research confirmed different maize varieties reacted differently to grey leaf spot in different locations in the different cropping seasons. this work is related with the findings of wang et al. (1998) and dunkel and levy (2000) who reported that there is evidence that the virulence of c. zeae-maydis is changing or that races of the pathogen exist predominantly. based on the research results of the present study, the epidemics of grey leaf spot were slightly higher at jimma than at hawassa in both 2014 and 2015 cropping seasons. this could be due to variation in altitude and associated amount, distribution and timing of rainfall and the variation in the day temperature. jimma area had longer extended period of rainfall and more rainy days than hawassa and mild mean daily temperature (that ranged from 14.1 to 26.3 oc) and higher relative humidity in the two cropping periods. these weather conditions might have strongly influenced the early initiation and progress of grey leaf spot in the cropping seasons. in line with the current alemu et al. east african journal of sciences volume 12 (1) 61-76 72 finding, beckman and payne (1982) and rupe et al. (1982) reported that grey leaf spot development is favored by extended periods of overcast days, warm temperatures and high relative humidity. high relative humidity, suitable air temperatures, host susceptibility and the presence of a source of inoculum are the conditions necessary to cause widespread and destructive outbreak of grey leaf spot. under field conditions, it was also observed that the disease was developed differently on the tested 12 maize varieties in the south and southwest ethiopia in the two testing seasons. the calculated disease progress rates were significantly (p < 0.05) different among the 12 maize varieties. several studies have also shown that environmental factors have tremendous impacts on the rate of within season grey leaf spot development. in ohio, denazareno et al. (1992) found that the rate of grey leaf spot progress (r) ranged from 0.13 to 0.17 logits per day under favorable conditions for disease development and 0.02 to 0.06 logits per day under less favorable conditions for gls development. nutter and stromberg (1999) also reported a similar result in iowa where they obtained more or less higher estimates of disease increase with rates of disease development ranging from 0.07 in 1991 (moderately favorable) to 0.28 logits per day in 1992 (extremely favorable). in south africa, ward et al. (1999) also found apparent infection rates of up to 0.10 logits per day (moderately favorable) up to 0.16 logits per day (highly favorable) during 1991/1992 rain season. table 8. correlation analysis among disease assessments with grain yield, thousand seed weight and phenological parameters at jimma and hawassa in 2014 and 2015 cropping seasons. parameters jimmaa psif audpc ir yield tsw ph dm psii 0.81*** 0.86*** 0.49** 0.12ns 0.19ns 0.33ns 0.37ns psif 0.97*** 0.89*** 0.16ns 0.48ns 0.29ns 0.33ns audpc 0.83*** 0.13ns 0.45ns 0.36ns 0.40ns ir 0.11ns 0.58** 0.25ns 0.25ns yield 0.28ns 0.22ns 0.17ns tsw 0.56** 0.32ns ph 0.81*** parameters hawassaa psif audpc ir yield tsw ph dm psii 0.71*** 0.87*** 0.35ns -0.08ns -0.06ns -0.35ns 0.52* psif 0.94*** 0.89*** -0.23ns 0.26ns -0.22ns 0.23ns audpc 0.74*** -0.16ns 0.12ns -0.30ns 0.35ns ir -0.22ns 0.37ns -0.18ns -0.04ns yield -0.10ns -0.46ns 0.03ns tsw 0.03ns 0.27ns ph -0.13ns note: initial and final disease severity (psi) of grey leaf spot, audpc = area under disease progress curve, ir = infection rate, tsw = thousand seed weight, ph = plant height and dm = days to maturity. **, * and ns correlation is significant at * p < 0.1, ** p < 0.01 and *** p < 0.001 levels and ns = no significant difference, respectively, and a/ = test locations. the epidemics of grey leaf spot progress were faster at jimma than at hawassa in both 2014 and 2015 main cropping seasons. this might be due to the inconsistency in environmental conditions, production systems and practices that worsened the problem to maximum. grey leaf spot was also favored by high rainfall and relative humidity, warm temperatures, and the presence of large amounts of inoculum. these current results are in agreement with previous findings that high grey leaf spot severity has been associated with locations and seasons with high precipitation (ringer and grybauskas, 1995). ringer and grybauskas (1995) also reported the disease components and grey leaf spot progresses under field conditions. these researchers concluded that rainfall and sporulation during early infection cycles had a significant effect on the development of grey leaf spot. they also postulated that early rains created favorable environmental conditions contributing to relatively high numbers of primary lesions that may provide sufficient inoculum to cause subsequent high levels of disease severity. rupe et al. (1982) also observed that high humidity was frequent in the two-week period prior to large increase in gls severity. in the present study, relatively the highest grain yield losses and the smallest thousand seed weight were observed at jimma in two testing seasons. this was because the disease started early at jimma and the growth stage of the crop was followed by very fast disease progress before the crop reached dent stage. this present investigation is in line with the work of ward et al. (1999) and dagne et al. (2001) who stated that the extent of damage is dependent on hybrid and on environmental conditions. increased incidence of alemu et al. reaction of improved maize varieties to grey leaf spot under field 73 grey leaf spot in africa has been associated with continuous cultivation of maize, and use of susceptible maize cultivars (denazareno et al., 1993; gevers et al., 1994). a study conducted on three commercial varieties, namely bh-660, bh-140 and phb-3253 in ethiopia for three consecutive years indicated that grain yield loss ranged from 0 to 36.9%, depending on the time of disease onset, disease severity and maize hybrid’s susceptibility and yield potential (tewabech et al., 2012). this indicates that grey leaf spot could be severe in some favorable seasons causing significant yield losses, even on resistant varieties (dagne et al., 2004). high levels of maize residue, moist conditions in the crop canopy, and susceptible hybrids are all factors that can contribute to yield loss caused by this grey leaf spot. fungicide application is costly and not practical in most operations for resource-poor farmers. when maize is planted into no-till fields with infested maize residues remaining on the soil surface and environmental conditions that are favorable for grey leaf spot development, grey leaf spot epidemics usually progress faster and reaches more damaging levels than in the fields where infected residues are either absent or greatly reduced (denazareno et al., 1992; ward et al., 1998). to this effect, grey leaf spot epidemics have been frequently reported from different parts of ethiopia (jimma, illubabor, west wellega, north omo and the sidam zones) in earlier years (dagne et al. 2001; tewabech et al., 2001; dagne et al., 2004; tewabech et al., 2011). furthermore, nzuve et al. (2013) stated that grey leaf spot is recognized as one of the yield-limiting diseases with yield losses ranging from 90 to 100% during times of grey leaf spot epidemics. yield losses associated with grey leaf spot occur when photosynthetic tissue is rendered non-functional due to lesions and/or the blighting of entire leaves. the blighting and premature death of leaves severely limits interception of radiation as well as the production and translocation of photosynthate to developing kernels. this is especially true for the upper eight or nine leaves, which contribute 75 to 90% of the photosynthate to grain filling (allison and watson, 1996). leaves of susceptible hybrids or inbreeds may become severely blighted or killed as early as 30 days prior to physiological maturity (jenco, 1995; ward et al., 1996). in ethiopia, dagne et al. (2004) also found that yield losses due to grey leaf spot on resistant, moderately resistant, and susceptible varieties ranged between 014.9, 13.7-18.3 and 20.8-36.9%, respectively, from 2003-2004 cropping seasons in bako and its nearby areas or vicinities. the findings of the present study revealed that gls severity had significant effect on grain yield at jimma and hawassa. this variation indicated that the disease development at both locations in the two testing seasons clearly showed that the disease becomes more severe when the susceptible plants are at the tasseling to grain filling stage. in the two testing seasons, disease severity assessment was positive but had nonsignificant impact on grain yields of all maize varieties at jimma, while the disease severity was negative but had non-significant impact on grain yield of all maize varieties at hawassa. this could be due to the higher contribution of the maize leaves in grain filling (converting photosynthetic products to grain). this evidently showed that grain yield loss could be high when disease severity occurs during vegetative and tasseling or silking to grain filling stage and low grain yield loss was found after grain filling stage. on the other hand, several factors may also contribute to this response, including yield potential of the varieties, growth stage of crops and the ability of leaf blighting to predispose the variety to stalk rots that result in high yield reduction. with reference to the area under disease progress curve at the two locations, audpc showed non-significant but negative association with grain yield. the present study indicated that yield reductions due to grey leaf spot were affected by disease severity and audpc. grain yield did not show strong and positive correlations with any of the disease parameters considered. in general, grain yield was significantly affected by maize variety but no significant difference was observed among varieties for the yield related trait, i.e. thousand seed weight. this means that varieties with low disease severity values had high thousand seed weight. on the other hand, there were strong and positive correlations among all disease parameters, such as gls severity, audpc and infection rate, that were affected by variety. significant reactions of varieties to the disease indicated that reduction in grain yield due to this disease varied from variety to variety, and that a specific variety showed different amount of yield depression due to disease. overall, the study showed that grey leaf spot (gls) attack on maize resulted in significant reduction in grain yield in the absence of any control measure. ward et al. (1999) suggested management of grey leaf spot through conventional tillage that buries crop residues, crop rotation, fungicides, and utilization of resistant varieties. fungicides are widely used in maize production (munkvold et al., 2001) but are too expensive for low income and resource-poor farmers in the tropics (menkir and ayodele, 2005). host plant resistance is found to be the most efficient and costefficient means of managing grey leaf spot and preventing leaf blighting (coates and white, 1994). however, no commercial hybrids with sufficient resistance presently exist in ethiopia, as they have not been improved for resistance to this specific disease so far (dagne et al., 2008). reportedly, breeding programs involved in developing resistance to grey leaf spot are alemu et al. east african journal of sciences volume 12 (1) 61-76 74 in progress (latter and rossi, 1983; ayers et al, 1985). inbreds and hybrids differs in their level of resistance to the disease, highly resistant lines have not been identified to date. horizontal resistance appears to be a viable option for improving the levels of grey leaf spot resistance in maize varieties (ayers et al, 1985). the results of this study demonstrated that the use of resistant maize varieties effectively reduced the disease severity and minimized grain yield losses. this implies that adequate levels of host resistance can prevent reduction in grain yield. the overall results of this study also demonstrated that all the released varieties in two tested locations showed susceptible reaction to grey leaf spot with the exception of hybrid varieties bh-660, bh-670, kuleni and morka that were relatively considered as resistant to gls in 2014 and 2015 cropping seasons. 5. conclusion in this field experiment under natural infection, it was identified that the performance of some maize varieties were generally consistent with results of previous seedling test experiments. in this case, moderately resistant varieties, such as gibe-2 and bh-543, have shown different host susceptible reaction, while the susceptible variety, such as local-k under field conditions, have shown similar host susceptible reaction. on the optimistic side, the varieties bh-660, bh-670, kuleni (improved open pollinated variety) and morka (improved open pollinated variety) showed promising resistant reaction to grey leaf spot in the field. the current results also designated that the maize varieties, such as bh-660 and bh-670, were considered as resistant under field conditions. under field condition, grey leaf spot was strongly affected by different resistant levels of maize varieties and difference in the environmental conditions. disease pressure had strong negative impact on grain-filling, which resulted in large amount of yield losses on susceptible maize varieties across locations. therefore, understanding relevant variables could play an important role in the management of this major disease of maize in ethiopia. ethiopia is a center of diversity for maize; various sources of resistant varieties could be obtained against grey leaf spot through resistant breeding programs. in conclusion, the present research confirmed that, under field conditions, different maize varieties responded differently to grey leaf spot and the disease severity was strongly affected by the use of different resistance levels of maize varieties and difference in the environmental conditions. it is therefore, promising to use the two maize varieties, such as bh-660 and bh670, were considered as resistant under field conditions and that are recommended to be used by farmers in south and southwest ethiopia as they had showed good performance such as moderate resistance to grey leaf spot, vigorous growth and high grain yield under field condition in two seasons of testing. further studies on the reaction of maize varieties to grey leaf spot should continue to identify and exploit genotypic differences among lines; resistant lines could be exploited by breeders to identify and develop cultivars with high degree of resistance so that they could be used either directly for production or indirectly as parents for developing hybrids. 6. acknowledgments this piece of scientific work was a component of the phd dissertation research at jimma university college of agriculture and veterinary medicine (jucavm). the authors are thankful to jimma university college of agriculture and veterinary medicine for financial and logistic supports. we are also very thankful to the national maize research program for providing seeds of maize varieties used for the study. the authors also thank hawassa agricultural research centers (harc) for provision of logistic support and facilities as well as for the assistance rendered by the staff. 7. references allison, j. c. s. and watson, d. j. 1996. the production and distribution of dry matter in maize after flowering. uk, london. annual botany, 30: 365-381. ayers, j. e., johnson, m. w. and hill, r. r. 1985. identifying resistance to grey leaf spot. rep 39th annual corn sorghum research conferences, 39: 157-175. bänziger, m., and diallo, a. o. 2004. progress in developing drought and n stress tolerant maize cultivars for eastern and southern africa. pp.189194. in: friesen, d. k. and palmer, a. f. e. 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3200, south africa. ward, j. m. j., laing, m. d. and cairns, a. l. p. 1997. management practices to reduce grey leaf spot of maize. journal of crop science, 37: 1257 1262. ward, j. m. j., stromberg, e. l., nowell, d. c. and nutter, f. w. j. 1999. grey leaf spot: a disease of global importance in maize production. plant disease, 83: 884-895. wheeler, b. e. j. 1969. an introduction to plant diseases, john wiley and sons limited, london, 374 pp. microsoft word paper-8(proof revised) final.docx ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (1) 95-98 licensed under a creative commons *corresponding author: e-mail: chemedabirhanu@gmail.com attribution-non-commercial 4.0 international license. registration of ‘kumsa’ finger millet (eleusine coracana) variety chemeda birhanu 1*, kebede dessalegn 1, dagnachew lule 2, girma chemeda 1, geleta geremew 1, megersa debela 1, girma mengistu 2, gudeta badada 1, hailu feyia1, bodena gudisa 1, megersa kebede1 and fufa anbassa1 1bako agricultural research center, p. o. box 03, bako, west shoa, ethiopia 2oromia agricultural research institute, addis ababa, ethiopia abstract: kumsa is a brown-seeded finger millet (eleusine coracana sub spp. coracana) variety. its pedigree is designated by bkfm 0063 (1). it is a selection from fourteen genotypes obtained from the ethiopian biodiversity institute, which had been collected from western parts of the oromia regional state, ethiopia. kumsa and other pipeline finger millet genotypes were evaluated against a standard check (gute) for grain yield, disease reaction, and other agronomic traits across two locations (bako and gute) for three consecutive years (2014-2016) during the main cropping seasons. additive main effect and multiplicative interaction (ammi), and genotype and genotype by environment interaction (ggi) biplot analysis showed that kumsa is stable, disease tolerant, and high yielder (3.17 t ha-1) with 25.3 % yield advantage over standard check gute (2.53 t ha-1). therefore, it was developed and released by bako agricultural research center for western oromia and similar agroecological areas of ethiopia in 2019. keywords: additive main effect and multiplicative interaction (ammi); disease resistant; genotype and genotype by environment interaction (ggi); grain yield; standard check; stability 1. introduction finger millet is a climate-resilient crop with highly nutritious and antioxidant properties (gupta et al., 2017). it is grown mainly by subsistence farmers in the drier regions of africa and serves as a food security crop because of its high nutritional value, excellent storage qualities and as a low input-requiring crop (dida et al., 2008). despite its importance, it is one of the neglected and underutilized crops (ayalew, 2015) in africa. more emphasize of improvement is often directed towards staple cereal crops such as maize, wheat, rice, barley, etc than finger millet. in ethiopia, finger millet, which is considered as a poor man's crop, is being grown by the rural poor farmers in marginal lands with low yielding potential, mainly in amhara and oromia regions (adugna et al., 2011; ayalew, 2015). low grain yield due to lack of stable and high yielding varieties with disease resistance is a major problem constraining widespread cultivation and use of finger millets in ethiopia (dagu et al., 2009; dagnachew et al., 2015). therefore, to address the problem, developing adaptable, stable, high yielding and disease resistant varieties is important. 2. varietal origin and evaluation kumsa [bkfm 0063 (1)] was developed through selection from finger millet landrace collections originally from western oromia regional state, east wollega zone, gobu sayo district, ethiopia. kumsa and other fourteen finger millet pipeline genotypes were evaluated against the standard check (gute) for three years (2014-2016) across two districts (locations), namely bako and gute. bako is located at 9º6’n latitude and 37º09’e longitude, and altitude of 1650 meters above sea level. the district receives mean annual rainfall of 1215.45 mm and its mean maximum and minimum temperatures are 14.0 and 28.4oc. gute is located at 9o01.06’n and 36o38.196’e, altitude 1915 meters above sea level. the district receives mean annual rainfall of 1431 mm and its mean maximum and minimum temperatures of the district are 12.3 and 32.0oc) (kebede et al., 2018). 3. agronomical and morphological characteristics the released variety, kumsa [bkfm 0063(1)] is characterized by light brown seed color, average 1000 seeds weight of 3.5 grams, and an average plant height of 85 cm (table 3). chemeda et al east african journal of sciences volume 14 (1) 95-98 96 4. yield performance the multi-location blast prone areas (bako and gute) and multi-year evaluation (2014-2016) data records indicated that kumsa [bkfm 0063(1)] is a stable and high yield variety which produced 2.5 3.2 t ha-1 on research station. on-farm (farmers’ field) yield evaluation recorded from variety verification plots at bako and gute revealed that kumsa gave an average grain yield ranging from 2.2 2.9 t ha-1 (tables 1 and 2). table 1. mean grain yield (t ha-1) and disease reaction across location over years. genotype mean grain yield (t ha-1) and disease reaction (1-5 scale) a bako gute mean lbs hbs 2014 2015 2016 2014 2015 2016 203353 1.70 4.92 2.37 3.39 1.17 1.15 2.45 3 2 203360 1.87 4.00 2.96 3.13 0.66 1.47 2.35 3 2 214988 1.78 3.55 2.01 4.13 0.79 1.34 2.27 4 3 214989 1.59 3.47 2.02 3.58 0.78 0.89 2.05 4 4 214997 1.92 4.05 4.52 3.58 0.88 0.99 2.66 4 4 229738 1.66 4.19 3.04 3.27 0.81 2.60 2.59 4 3 230103 1.65 3.12 3.98 3.48 1.17 2.90 2.72 4 2 bkfm0052 2.05 4.03 2.98 4.10 1.28 2.08 2.76 4 3 bkfm0007 1.73 4.10 2.33 4.05 2.52 1.84 2.75 3 2 bkfm0034 1.64 2.72 2.20 3.77 0.39 1.35 2.01 3 2 bkfm0042 1.77 3.91 2.54 4.27 1.51 0.72 2.45 3 2 bkfm0043 1.64 3.81 1.89 3.20 0.81 2.35 2.28 3 2 bkfm0063(1) 1.84 4.61 4.83 3.91 1.90 1.91 3.17 2 2 gute 1.95 4.25 2.22 4.06 0.60 2.11 2.53 3 3 local 1.40 2.93 2.20 3.75 1.35 1.27 2.15 3 2 mean 1.75 3.98 2.67 3.71 1.11 1.66 2.48 lsd 0.70 1.02 1.19 1.03 0.48 0.63 cv 23.8 16.7 27.9 18.7 26 22.6 f-value ns ** ** ns ** ** note: a blast severity (1= highly resistant, 2 = resistant, 3 = moderately resistant, 4 = susceptible and 5= highly susceptible, ** significant at 0.01 probability level; ns = non-significant; lbs = leaf blast severity, hbs = head blast severity, lsd = least significant difference. cv = coefficient of variation. 5. stability and adaptability analysis eberhart and russell (1966) model revealed that kumasa [bkfm 0063 (1)] variety showed a regression coefficient (bi) closer to unity (figs 1 and 2) and thus is a more stable and widely adaptable variety than the remaining genotypes. both gge biplot and ammi analysis also indicated that kumsa [bkfm 0063 (1)] was stable and high yielding, which gave about 25.3% (31.17 t ha-1) yield advantage over the standard check gute (2.53 t ha-1). hence, the variety was officially released and recommended for production in the testing locations and areas with similar agro-ecological conditions to boost production and productivity of the crop. accordingly, kumsa was recommended for western oromia areas (bako, gute and bilo) as well as for areas with similar agro ecological conditions. chemeda et al registration of ‘kumsa’ finger millet variety 97 figure 1. gge biplot analysis showing grain yield stability of genotypes and environments. figure 2. ammi biplot showing genotypes grain yield stability and preferential adaptation over environment. 6. reaction to diseases the variety was evaluated in blast prone areas at bako and gute. accordingly, kumsa is resistant to blast (magnaporthe oryzea), a devastating major disease of finger millet that affect all above ground parts of the plant (table 1). comparison biplot (total 63.63%) 229738 bkfm0043 bkfm0007bkfm0042203360 bkfm0034 214989 local 203353 214988 214997 gute bkfm0005 bkfm00-63(1) 230103 b15 b16 g14 g15g16 b14 pc1 40.43% p c 2 2 3 .2 0 % aec environment scores genotype scores plot of gen & env ipca 3 scores versus means bkfm0034 230103 gute bkfm0007 bkfm0043 203360 bkfm0042 214989 229738 214988 214997 203353 local bkfm0005 bkfm00-63(1) g16 g15 b14 b15 b16 g14 1000 -40 2000 -30 3000 -20 4000 -10 0 10 20 2500 1500 3500 ip c a s co re s genotype & environment means chemeda et al east african journal of sciences volume 14 (1) 95-98 98 table 2. agronomic/morphological characteristics of finger millet variety, kumsa. variety name kumsa [acc. bkfm 0063 (1)] agronomic and morphological characters adaption areas: bako, gute, bilo boshe and similar agro-ecologies  altitude (m.a.s.l.)a 1500-2200  rainfall (mm) 1200-1300 seed rate (kgha-1) 15 spacing (cm) 40 cm x 10 cm planting date late may to mid-june fertilizer rate (kgha-1) 105 for dap and 65 for urea, respectively days to maturity (days) 144 1000 seed weight (g) 3.5 plant height (cm) 85 seed color light brown growth habit erect crop disease reaction tolerant to blast (leaf and head) finger millet disease yield (t ha-1)  research field 2.5 3.2  farmers field 2.2 2.9 year of release 2019 breeder seed maintainer bako agricultural research center note: a m a.s.l. = meters above sea level. 7. conclusions kumsa finger millet variety was released for its high grain yield, showed better adaptability and stable performance than the standard check. the variety is also tolerant to blast disease. therefore, it was released and recommended for smallholder farmers and other finger millet producers at bako, gute, bilo and areas with similar agro-ecologies in the country to boost finger millet productivity. 8. acknowledgments the authors would like to acknowledge oromia agricultural research institute for funding the research work. the authors also thank bako agricultural research center and all staff members of the cereal technology generation team for implementation of the experiment. 9. references adugna, a., tesso, t., degu, e., tadesse, t., merga, f., legesse, w., tirfessa, a., kidane, h., wole, a. and daba, c. 2011. genotype-by-environment interaction and yield stability analysis in finger millet (elucine coracana l. gaertn) in ethiopia. american journal of plant sciences, 2(03): 408-415 ayalew, b. 2015. trends, growth and instability of finger millet production in ethiopia. research journal of agriculture and environmental management, 4(2): 078-081. dagnachew, l., kassahun, t., awol, a., masresha, f., kebede, d., girma, m., geleta, g., hailu, f., kassa, m., chemeda,b., girma, c. and gudeta, b. 2015. registration of “addis-01” finger millet variety. east african journal of science, 9 (2): 141142. degu, e., adugna, a., tadesse, t. and tesso, t. 2009. genetic resources, breeding and production of millets in ethiopia, in new approaches to plant breeding of orphan crops in africa. proceedings of an international conference, bern switzerland, 1921 september, 2007 dida, m.m., wanyera, n., dunn, m.l.h., bennetzen, j.l. and devos, k.m. 2008. population structure and diversity in finger millet (eleusine coracana) germplasm. tropical plant biology, 1(2): 131-141. eberhart, s.a. and russell, w.a. 1966. stability parameters for comparing varieties. crop science, 6 (1): 36-40. gupta, s.m., arora, s., mirza, n., pande, a., lata, c., puranik, s., kumar, j. and kumar, a. 2017. finger millet: a “certain” crop for an “uncertain” future and a solution to food insecurity and hidden hunger under stressful environments. frontiers in plant science, 8 (643): 1-11 kebede, d., dagnachew, l., megersa, d., chemeda, b., girma, m., geleta, g. and gudeta, b., 2019. genotype by environment interaction and grain yield stability of ethiopian black seeded finger millet genotypes. african crop science journal, 27(2): 281-294. east african journal of sciences (2019) volume 13 (1) 51-64 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: misganawaytenfsu@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) distribution and association of common bean angular leaf spot (phaeoisariopsis griseola) with biophysical factors in southern and southwestern ethiopia misganaw aytenfsu 1*, habtamu terefe 1, and getachew ayana 2 1 department of horticulture, mizan-tepi university, p.o. box 260, mizan-tepi, ethiopia 2 melkassa agricultural research center, eiar, p. o. box 436, adama, ethiopia abstract: in ethiopia, the average yield of common bean is low due to a wide range of factors. angular leaf spot (als), caused by phaeoisariopsis griseola, is one of the most destructive diseases in major bean growing areas of the country. therefore, a field survey was conducted in four districts and two agricultural research centers to determine the distribution and importance of als intensity and its association with different biophysical factors in southern and southwestern parts of ethiopia. in the survey, als was found prevalent in all common bean growing fields. however, mean incidence and severity varied among independent variables and variable classes. mean incidence varied from 66.35% in awassa zuria district to 88.06% in jimma agricultural research center (jarc), whereas mean severity ranged from 81.14% in bako tibe district to 90.58% in hawassa agricultural research center (harc). higher mean incidence of 81.57% was obtained at altitude of >1718m.a.s.l than lower altitude class. the highest (86.56%) disease severity was obtained at pod filling stage compared to other growth stages. the independent variables showed a variable association response to als disease intensity in logistic regression model. variables like districts, cropping system, growth stage, sowing date and weed density were significantly (p ≤ 0.05) associated with disease incidence. low mean disease incidence had high probability of association to bako tibe district, lower weed density and intercropping system. similarly, low mean disease severity had high probability of association to bolloso sore district and lower altitudinal range. findings of this study showed that als is a major constraint of common bean production, implying the need for proper intervention to improve available common bean varieties through careful weeding, intercropping practices and use of clean seed in the study areas and other agro-ecologies. keywords: angular leaf spot; biophysical factors; common bean; incidence; severity 1. introduction common bean (phaseolus vulgaris l.) is widely cultivated in tropical and subtropical countries. it is an important source of proteins, carbohydrates, fiber, vitamins and minerals (voysest, 2000). its high nutritional value and high rate of consumption make common bean an important food for many people in developing countries in africa, asia, and latin america (beebe, 2014). worldwide, about 22.8 million metric tons (mt) of dry beans were produced and india is the highest producer with an annual production of more than 4 million mt (fao, 2012; faostat, 2014). common bean is grown widely and is becoming an important commodity in the cropping systems of smallholder producers both for food security and income in ethiopia. the crop is widely grown in areas between 1400-2000 m. according to csa (2017), about 290, 202.43 ha of land was allocated for common bean production and a total of 483,922.66 ton was obtained with an average productivity of 1.60 t ha-1 for white and 1.69 t ha-1 for red common beans in the 2016/17 main cropping seasons in ethiopia. however, productivity of common bean is constrained by several factors including a wide range of biotic, abiotic and socio-economic issues that limit the genetic potential of the crop (singh and schwartz, 2010). among biotic factors, diseases and pests are affecting the production and productivity of common bean in ethiopia (kutangiet al., 2010). different diseases are reported as major constraints that threaten the productivity of common bean in the country. of which, anthracnose (colletotrichum lindemuthianum), rust (uromysis appendiculatus), angular leaf spot (phaeoisariopsis griseola) and common bacterial blight (xanthomonas campestris pv. phaseoli) are the dominant ones (yesuf, 2005). among the major fungal diseases, angular leaf spot (als) is one of the most destructive diseases of common bean in tropical and subtropical regions of the world (allorent and savary, 2005). the disease is favored by intermittent dry-wet and warm-cool weather (correavictoria et al., 1989). under favorable temperature conditions of 18 to 24 oc, high humidity (>70%) and in the presence of a susceptible host, the pathogen has the ability to colonize different parts of bean plants including leaves, pods and seeds (stenglein et al., 2003). about 47% yield reduction of common bean due to als is reported so far in ethiopia (fikre et al., 2011). different production practices and variation in climatic conditions are thought to influence disease occurrence, epidemics development and damage to the crops under misganaw et al. east african journal of sciences volume 13 (1) 51-64 52 field conditions (allerent and savary, 2005; mwangombe et al., 2007). the effects of the disease also vary from season to season, between production situations, agroecological areas and other biophysical factors. the effects of various management practices like cropping system on disease prevalence and intensity was reported (fernandez et al., 2011). and also resistant varieties have been suggested as a cost effective strategy to manage the disease at small scale farms (mahuku et al., 2009). however, deployment of resistant varieties for the control of als requires understanding of environmental, cultural and epidemiological factors (singh, 2007). understanding the association of disease intensity with cropping systems, crop combinations and management practices would help to identify the most important variables and to develop an integrated and sustainable management options (rusuka et al., 1997; zewde et al., 2007). in spite of this, information on disease occurrence, importance and effects of different agronomic practices, environmental variables and other biophysical factors on als of common bean are limited in ethiopia. thus survey studies are found useful to gain insights into the distribution and relative importance of plant diseases. therefore, the objectives of this study were to determine (1) the prevalence, intensity and relative importance of angular leaf spot of common bean in southern and southwestern ethiopia and (2) the association between disease intensity with different biophysical factors in the study areas. 2. materials and methods 2.1. the survey areas survey of angular leaf spot of common bean was conducted in four major common bean growing districts (bako tibe, kerisa, bollosso sore and awassa zuria) and two agricultural research centers, namely hawassa agricultural research center (harc) and jimma agricultural research center (jarc) of southern and southwestern ethiopia during the 2017 main cropping season. bollosso sore is located in wolaita zone of southern nations, nationalities and peoples region (snnpr), while awassa zuria and harc are placed in sidama zone of snnpr. bako tibe is located in west shoa zone of oromia national regional state (onrs), of ethiopia, whereas kerisa and jarc are found in jimma zone of onrs (figure 1). the surveyed districts are different in agro-ecological characteristics and weather conditions (table 1).the districts were selected purposively as the disease is frequently reported in those areas and with due consideration in potential of bean production, spatial and ecological location which representing the diverse conditions under which beans are cultivated. table 1. characteristic features of surveyed common bean districts and research centers in southern and southwestern ethiopia, during the 2017 cropping season. district and research centre altitude (m.a.s.l) latitude longitude relative humidity (%) mean temperature range (°c) jarc 1774-1814 7°40.11''-7°40.13'' 36°40.50''-36°47.53'' 48.05-50.6 28-28.7 kersa 1746-1785 7°42.41''-7°42.799'' 37°00.00''-37°00.62'' 50.45-64.4 22.05-28.65 bako tibe 1602-1681 9°01.30''-9°06.23'' 36°59.70''-37°02.52'' 31.5-49.25 26.45-32.1 bolloso sore 1760-1801 7°03.040''-7°05.123'' 37°41.142'-37°41.924'' 50.3-72.45 24.4-30.45 harc 1696-1702 7°03.616''-7°03.640'' 38°30.517''-38°30.565'' 45-46.3 25.8-27.65 awassa zuria 1686-1750 7°00.803''-7°01.380'' 38°22.154''-38°23.911'' 36.85-57.15 27.05-32.1 2.2. sampling and sample units group discussions were held with development agents and agricultural district officials who are working with farmers to have broader understanding of the production potentials of common bean and route in the survey kebeles (small population unit in the district = peasant association) and fields. formal survey questionnaires were prepared to gather the information from the farmers via personal interviews. the maximum of three peasant associations (pas) were selected from bolloso sore district and about 17 fields were assessed from them. similarly, two pas each were selected from awassa zuria and bako tibe districts, and 12 and 10 fields were assessed, respectively. on the other hand, only one pa and seven fields were assessed from kerisa district. the rest nine fields were assessed from research centers (four from jarc and five from harc) and a total of 55 fields were surveyed from all districts and research centers. peasant associations per district were selected purposively based on intensity of bean production, while fields were randomly selected at intervals of about 5 km along the main and accessible rural roads. within selected fields, four quadrats (1m2) diagonally spaced about 5 to 8 m apart were sampled. then, plant samples exhibiting symptoms of angular leaf spot disease were assessed systematically for each field. misganaw et al. common bean angular leaf spot (phaeoisariopsis griseola) with biophysical factors 53 figure 1. map showing districts and zones (where each respective research center is found) surveyed for angular leaf spot (phaeoisariopsis griseola) of common bean in southern and southwestern ethiopia. 2.3. geographical and agronomic data global positioning system (gps) instrument was used to determine the coordinates (latitude and longitude) and altitude of each field visited. gps based survey sheet was prepared to collect information on disease status from each area. additionally, data on agronomic parameters like field size, cropping systems (sole or intercropping), planting date, weed density, planting pattern (row or broadcast), growth stage and plant density were collected to determine the relationship with disease intensity. information like planting date was obtained from growers through interview. the plant population and weed density were assessed using 1m2 area placed diagonally three times within a field. the mean plant and weed population density were obtained by taking the average number of population in four quadrants. the average value of relative humidity and temperature of surveyed fields were also measured using thermos-hygrometer. 2.4. disease assessment angular leaf spot incidence was determined from priory laid four quadrats of 1m2 in each inspected field across districts and research centers, while disease severity was scored from randomly taken 20 plants per field using standard scoring scales. 2.4.1. disease incidence angular leaf spot incidence was assessed by counting the number of plants showing typical als symptoms in the four quadrats (1m2) and incidence per farm was computed using the following formula: x100 counted plants of no. total infected plants of no. total (%) incidence  2.4.2. disease severity angular leaf spot severity was rated from 20 randomly selected plants per field by scoring five representative plants for each spaced quadrat using standard scales of 1 to 9 (pastor-corrales and jara, 1995). the description of the scales is given in table 2. table 2. scales, parts affected and descriptions of scales used to score angular leaf spot severity. scale plant parts affected by angular leaf spot 1 no visible disease symptoms; 2 the presence of up to 3% leaf lesions; 3 the presence of up to 5% leaf lesions, without sporulation of the pathogen; 4 the presence of sporulating lesions covering 10% of the leaf area 5 the presence of various sporulating lesions from 2 to 3 mm in size, covering 10-15% of the leaf area; 6 presence of numerous sporulating lesions greater than 3 mm in size, covering 15-20% of the leaf area 7 the presence of numerous sporulating lesions greater than 3 mm in size, covering 20-25% of the leaf area; 8 presence of numerous sporulating lesions greater than 3 mm in size, covering 25-30% of the leaf area 9 >30% of the leaf or pod surface area is covered by large sporulating and often coalescing lesions. leaf tissues are generally chlorotic resulting in severe and premature defoliation. infected pods are often deformed and shriveled and contain a low number of seeds. abundant sporulating lesions are present on stem and branches. misganaw et al. east african journal of sciences volume 13 (1) 51-64 54 the severity grades obtained were converted into percentage severity index (psi) using the formula suggested by whleer (1969). 100 scaleon score m aximum x scored plants ofnumber total ratings numarical of sum psi x 2.5. data analysis simple descriptive statistics were used to summarize data obtained from field surveys after using stata computer program version 12 for windows. summary of incidence and severity of angular leaf spot was presented for each independent variable and variable classes. disease incidence and severity data were classified into distinct classes of bivariate qualitative data. class boundaries were chosen so that classes contained approximately equal numbers. contingency table of independent variables by disease intensity was built to represent the bivariate distribution of fields according to two classifications (e.g. weed density by als incidence) (table 3). an entry in a cell of a contingency table represents the frequency of fields falling into that cell. t-tests were used to compare the frequencies of diseased fields between sowing date, cropping pattern, cropping system and plant population based on the proportion of fields in each district that were assigned to a given disease incidence class (samuel et al., 2008a). the associations of als intensities with independent variables were analyzed using logistic regression as described by yuen et al. (1996) and hosmer and lemeshow (1989) with the sas procedure genmod (sas, 2007). the logistic regression model allows evaluation of the importance of multiple independent variables that affect the response variable. logistic regression calculates the probability of a given binary outcome as a function of the independent variables (mccullagh and nelder, 1989). if the predicted probability of the outcome is denoted as (p), the logistic regression model assumes the logarithm of the odds of p (p/(1-p)), which equals logit (p), and is a linear function of the independent variables (yuen et al., 1996). the genmod procedure gives parameter estimates and standard error of the parameter estimates. exponentiation the parameter estimate yields the odds ratio, which is interpreted here as the relative risk (yuen et al., 1996). the importance of each independent variable was evaluated in two ways. first, the association of an independent variable alone with disease incidence or severity was tested in a single variable model. this consisted of testing the deviance reduction attributed to a variable when it first enters into the model. second, the association of an independent variable with disease incidence or severity was tested when enter last in to the model with all other independent variables. the deviance was used to compare different models. the difference between two models, a likelihood ratio test (lrt) was used to examine the importance of variables and was tested against a χ2 value (mccullagh and nelder, 1989). misganaw et al. common bean angular leaf spot (phaeoisariopsis griseola) with biophysical factors 55 table 3. categorization of variables used in analysis for distribution of angular leaf spot epidemics of common bean in four different districts and two research centers (n = 55) of southern and southwestern ethiopia, during the 2017 cropping season. variable variable class number of fields angular leaf spot intensity incidence severity ≤80% >80% ≤85% >85% district bolloso sore 17 6 11 11 6 harc a 5 1 4 1 4 awassa zuria 12 11 1 4 8 bako tibe 10 3 7 5 5 jarc b 4 0 4 1 3 kerisa 7 2 5 3 4 altitude (m.a.s.l) ≤1718 26 14 12 10 16 >1718 29 9 20 15 14 field size (m2) ≤1000 30 10 20 13 17 >1000 25 13 12 12 13 sowing date late june-june 30 23 5 18 9 14 >august 01 32 18 14 16 16 cropping pattern row planting 46 16 30 22 24 broadcasting 9 7 2 3 6 cropping system c sole cropping 42 13 29 19 23 intercropping 13 10 3 6 7 growth stage flowering 15 12 3 7 8 pod filling 29 9 20 13 16 maturity 11 2 9 5 6 plant density d ≤34 19 11 8 11 8 >34 36 12 24 14 22 weed density e ≤50 36 15 21 14 22 >50 19 8 11 11 8 incidence ≤80% 23 … … .. .. >80% 32 .. .. .. .. severity ≤85% 25 .. .. .. .. >85% 30 .. .. .. .. note: a harc = hawassa agricultural research center and b jarc = jimma agricultural research center; c cropping system in which intercropping refers to common bean fields planted with maize, enset, coffee and/or sweet potato; d plant density was determined as number of plants per 1 m2 quadrat; e weed density was determined as number of weeds less than or equal to 50 or greater than 50 per 1m2 quadrat. field size was measured in m2. 3. results 3.1. overview of surveyed fields out of 55 common bean farms inspected, the most (30.9%) and least (7.27%) number of farms were assessed in bolloso sore district and jarc, respectively. similarly, both of the smallest (100 m2) and the largest (3,333.33 m2) field sizes were visited in bolloso sore and over 54% of observed fields were below 1000 m2. about 58% of common bean farms were sown in august, while the remaining farms were sown from late june to the end of july. most (83.64%) of surveyed fields were row planted and the rest farms were broadcasted. with regard to cropping system, 76.36% of inspected farms were sole cropped and the remaining 23.64% was intercropped with maize, enset, coffee and/or sweet potato. common bean fields were found at three growth stages during the time of survey in which 27.27%, 52.73% and 20% were at flowering, pod filling and maturity growth stages, respectively. none of the common bean growers were used chemical spray as angular leaf spot management option, but over 40% of growers were found to apply cultural practices like rouging and cutting of diseased plants and plant parts as disease management schemes to reduce rapid pathogen dispersal among plant canopies. high weed infestation was observed in kerisa and some part of bolloso sore districts. in addition, some other common bean diseases and pests were also observed in association with als. all districts, excluding awassa misganaw et al. east african journal of sciences volume 13 (1) 51-64 56 zuria, showed floury leaf spot (mycovellosiella phaseoli). on the other hand, about 35% of awassa zuria farms were infected by rust (uromyces appendiculatus). moreover, bean stem maggot (ophiomyia phaseoli) was encountered as key insect pest in kerisa as 71.43% of observed fields were showed maggot (larvae) on stem of plants. 3.2. distribution and disease intensity of angular leaf spot angular leaf spot was prevalent and widely distributed in all common bean fields studied. however, there was variation in mean disease incidence and severity of als among independent variables and variable classes (table 4 and figure 2). different level of als incidence and severity were recorded among districts and research centers. higher mean disease incidence (88.06%) was obtained in jarc compared to the other districts and research centers. contrary, mean disease incidence in awassa zuria district was lowered by 24.65%, 19.93%, 17.44%, 16.71% and 15.63% compared to jarc, bako tibe, harc, bolloso sore and kerisa, respectively. on the other hand, minimum mean disease severity of als was recorded in bako tibe (81.14%) and the maximum was obtained in harc (90.58%). mean disease severity in harc was 2.78%, 4.87%, 6.03%, 6.54% and 10.42% higher than jarc, awassa zuria, kerisa, bolloso sore and bako tibe, respectively. higher mean disease incidence of 81.57% was obtained in altitude of >1718m.a.s.l than lower altitude class. similarly, mean disease severity was one and half percent higher in semi-highland areas (altitude >1718m.a.s.l) than semilowland areas (altitude ≤1718m.a.s.l). there were no much mean incidence and severity variation between variable classes of field size and sowing date. conversely, intercropped fields reduced disease incidence by 13.47% than sole cropping. on the other hand, mean disease severity was 1.21% higher in intercropped fields than sole cropped fields. regarding cropping pattern, mean disease incidence in row planted fields was 10.84% higher than broadcasted fields, while mean severity was 1.94% higher in broadcasted fields than row planted fields. with regard to growth stage, mean disease incidence at maturity growth stage was 19.98% and 4.11% higher than flowering and pod filling growth stages, respectively. mean disease severity at pod filling stage was 5.39% and 2.16% higher than maturity and flowering growth stages. this indicates that growth stage might have an influence to the disease epidemics. there was a variation in mean disease incidence with regard to crop and weed density even though the variation in mean disease severity was minimum. the mean disease incidence was higher in highly weed infested farms than farms with low to free weed infestations. likewise, mean disease incidence reduced by 8.38% in sparsely populated farms to densely populated beans. unfortunately, we failed to report varietal differences in incidence and severity of angular leaf spot due to lack of sufficient information upon the survey period. comparison of common bean fields of low and high plant population, cropping system (sole cropping and intercropping), early (late june to july 30) and late (>august 01) planting as well as cropping pattern (row planting and broadcasting) with disease incidence showed significant (p ≤ 0.05) variation in t-test (table 5). cropping system showed high association to disease incidence (t-value = 3.1, p < 0.0031), followed by sowing date (t-value = 2.67, p < 0.0099). however, none of the variables showed significant association with disease severity (data not shown). figure 2. mean disease incidence and severity of angular leaf spot across different districts and research centers in southern and southwestern ethiopia, during the 2017 cropping season. misganaw et al. common bean angular leaf spot (phaeoisariopsis griseola) with biophysical factors 57 table 4. mean disease intensity of angular leaf spot of common bean for different independent variables in southern and southwestern ethiopia, during the 2017 cropping season. variable variable class angular leaf spot intensity incidence (%) severity (%) min. max. mean sd a min. max. mean sd a district bolloso sore 52.93 93.94 79.66 12.42 77.14 94.67 84.66 5.03 harc b 72.4 84.27 80.37 4.69 82.22 96 90.58 5.49 awassa zuria 50.07 84.99 66.35 9.53 73.33 93.33 86.17 6.41 bako tibe 66.67 93.33 82.87 9.15 60 90 81.14 10.69 jarc c 86.14 92.01 88.06 2.73 83.33 91.42 88.06 3.79 kerisa 50.07 95.56 78.64 11.97 60 96 85.12 7.11 altitude(m.a.s.l) ≤1718 50.07 93.33 75.36 11.73 60 96 84.84 8.64 >1718 52.93 95.56 81.57 11.61 72 94.67 85.37 5.53 field size (m2) ≤1000 50.07 93.94 79.71 12.06 62.86 96 85.32 6.57 >1000 59.64 95.56 77.33 11.99 60 94.67 84.87 7.84 sowing date late june-july 30 66.34 93.94 83.46 7.76 60 96 85.14 8.5 >august 01 50.07 95.56 83.46 7.76 60 96 85.14 8.5 cropping pattern row planting 50.07 95.56 80.06 12.06 60 96 84.84 7.44 broadcasting 61.77 87.95 71.38 8.89 77.78 94.67 86.52 5.18 cropping system d sole cropping 52.93 95.56 81.22 11.15 60 96 84.87 7.49 intercropping 50.07 88.98 70.28 11.01 76 94.67 85.91 5.89 growth stage flowering 50.07 92.06 68.11 11.35 72 94.67 84.69 5.84 pod filling 52.93 95.56 81.62 10.49 73.33 96 86.56 5.9 maturity 68.64 93.33 85.12 6.87 60 90.83 81.89 10.48 plant density e ≤34 50.07 93.33 74.19 13.63 73.33 94.67 85 6 >34 54.32 95.56 80.98 10.45 60 96 85.18 7.71 weed density f ≤50 52.93 93.94 78.38 11.83 60 96 85.6 7.62 >50 50.07 95.56 79.12 12.56 72 93.33 84.2 6.1 note: a sd = standard deviation; b harc = hawassa agricultural research center; c jarc = jimma agricultural research center; d cropping system in that intercropping refers to planting common bean fields with maize, enset, coffee and/or sweet potato; e plant density was determined as number of plants per 1 m2 quadrat; f weed density was determined as number of weeds less than or equal to 50 or greater than 50 per 1m2 quadrat. table 5. contingency t-test analysis of mean disease incidence difference of angular leaf spot of common bean, southern and southwestern ethiopia, during the 2017 cropping season. independent variable variable class angular leaf spot incidence se t-value p-value plant density a ≤34 1.74 2.06** 0.0445 >34 3.13 cropping system b sole cropped 1.72 3.10*** 0.0031 intercropped 3.05 sowing date late june -july 30 1.62 2.67*** 0.0099 >august 01 2.35 cropping pattern row planting 1.78 2.05** 0.0457 broadcasting 2.96 note: *** and ** indicates that there is significant difference in the frequency of diseased fields based on disease incidence at p<0.001 and p ≤ 0.05, respectively; a plant density was determined as number of plants per 1 m2 quadrat; b cropping system in that intercropping refers to planting common bean fields with maize, enset, coffee and/or sweet potato. misganaw et al. east african journal of sciences volume 13 (1) 51-64 58 3.3. association of angular leaf spot intensity with biophysical factors the independent variables showed a variable association response to angular leaf spot incidence and severity (table 6). variables including district (χ2 = 149.48, 5df), cropping system (χ2 = 5.95, 1df), growth stage (χ2 = 67.91, 2df), field size (χ2 = 4.1, 1df), sowing date (χ2 = 7.3, 1df) and weed density (χ2 = 3.82, 1df) were significantly (p ≤ 0.05) associated with als incidence in logistic regression model. however, field size lost its significance when entered last into the model. on the other hand, district (χ2 = 21.61, 5df), cropping system (χ2 = 4.06, 1df), growth stage (χ2 = 47.68, 2df), sowing date (χ2 = 8.9, 1df) and weed density (χ2 = 3.82, 1df) maintained their association with als incidence when entered into the reduced variable model. variables such as altitude (χ2 = 0.06, 1df), cropping pattern (χ2 = 0.92, 1df) and plant density (χ2 = 0.18, 1df) were not significantly (p ≤ 0.05) associated with als incidence when entered first and last into the model. the influencing magnitude of sowing date on disease incidence slowly increased, while the contribution of district, cropping system and growth stage to incidence decreased in the reduced model (table 6). growth stage was the most significantly associated variable with angular leaf spot incidence when entered first and last into the model (χ2 = 67.91 and 47.68, p < .0001, 2df). all significantly associated variables, excluding field sizes, were tested in reduced multiple variable model and their analysis of deviance showed the importance of each variable and variable class to mean disease incidence (table 7). the parameter estimate and standard error resulted from reduced regression model are shown in table 7. the probability of als incidence >80% was highly associated to kerisa, jarc and bolloso sore districts, in sole cultures, at pod filling to maturity growth stage, in early planting and in farms with high weed infestation. on the other hand, low incidence had high association to bako tibe and harc districts, intercropping system, flowering growth stage, late planting and farms with low weed infestation. the probability of occurrence of high incidence in jarc was twice higher than disease incidence in bako tibe and harc. similarly, the probability of occurrence of high incidence in sole culture was about 1.2 times higher than incidence in intercropping system. regarding growth stages, the probability of occurrence of high incidence at flowering stage was about twice and 2.5 times lesser than pod filling and maturity growth stages, respectively. there were 1.37 and 1.2 times higher probability of high disease incidence could occur in early planting and high weed density (>50) than disease epidemics in late planting and low weed density, respectively. table 6. independent variables used in logistic regression model for angular leaf spot intensity and their likelihood ratio test in southern and southwestern ethiopia, during the 2017 cropping season. variable df angular leaf spot incidence lrt a angular leaf spot severity lrt a vef vel vef vel dr pr > χ2 dr pr > χ2 dr pr > χ2 dr pr > χ2 district 5 149.48 <.0001 21.61 0.0006 29.37 <.0001 24.49 0.0002 altitude 1 0.06 0.81 0.36 0.55 4.07 0.043 6.11 0.013 field size 1 4.1 0.04 1.45 0.23 3.85 0.049 2.63 0.104 cropping system 1 5.95 0.015 4.06 0.044 0.25 0.62 0.58 0.45 growth stage 2 67.91 <.0001 47.68 <.0001 1.62 0.44 3.13 0.21 cropping pattern 1 0.92 0.34 2.56 0.11 2.88 0.089 2.95 0.086 sowing date 1 7.3 0.0069 8.9 0.0028 2.26 0.13 2.12 0.12 plant density 1 0.18 0.67 0.27 0.6 0.41 0.52 1.04 0.31 weed density 1 3.82 0.05 3.82 0.05 0.9 0.34 0.9 0.34 note: a lrt= likelihood ratio test; vef = variable entered first; vel = variable entered last; df = degrees of freedom; dr = deviance reduction; pr = probability of a value χ2 exceeding the deviance reduction; χ2 = chi square. misganaw et al. common bean angular leaf spot (phaeoisariopsis griseola) with biophysical factors 59 table 7. analysis of deviance, natural logarithms of odd ratio and standard error of als incidence and likelihood ratio test on independent variables in southern and southwestern ethiopia, during the 2017 cropping season. added variable residual deviance a df als incidence lrt b variable class estimate loge (odds ratio)c sed odds ratio dr pr > χ2 intercept 460.74 0 2.3151 0.23 10.13 district 311.26 5 14.86 0.0001 bolloso sore -0.6011 0.16 0.55 8.88 0.0029 harc -1.0241 0.34 0.36 11.38 0.0007 awassa zuria -0.9724 0.29 0.38 9.42 0.0022 bako tibe -1.1113 0.36 0.33 2.09 0.148 jarc -0.3279 0.23 0.72 kerisa 0* . cropping system 301.15 1 4.06 0.044 sole cropping 0.2339 0.12 1.26 intercropping 0* . growth stage 233.24 2 20.93 <.0001 flowering -0.9742 0.21 0.38 2.44 0.12 pod filling -0.2786 0.18 0.76 maturity 0* . sowing date 225.02 1 8.75 0.0031 late june to july30 0.3149 0.11 1.37 >august 01 0 0 . weed density 221.02 1 3.84 0.05 ≤50 -0.2013 0.10 0.82 >50 0* . note: a unexplained variations after fitting the model; b lrt = likelihood ratio test; c* reference group; d se = standard error; dr = deviance reduction; df = degrees of freedom; pr = probability of a value χ2 exceeding the deviance reduction; χ2 = chi square. table 8. analysis of deviance, natural logarithms of odd ratio and standard error of angular leaf spot severity and likelihood ratio test on independent variables in southern and southwestern ethiopia, during the 2017 cropping season. added variable residual deviance a df als severity lrt b variable class estimate loge (odds ratio)c se d odds ratio dr pr > χ2 intercept 201.9159 0 1.6212 0.2735 5.06 district 172.5443 5 2.29 0.13 bolloso sore -0.251 0.1658 0.78 7.45 0.0063 harc 1.3412 0.4913 3.82 3.54 0.06 awassa zuria 0.8185 0.4353 2.27 1.87 0.1719 bako tibe 0.6791 0.4972 1.97 0.61 0.4366 jarc 0.1882 0.2419 1.21 kerisa 0* . altitude 168.4765 1 5.26 0.0219 ≤1718 -0.9854 0.4298 0.37 >1718 0* . note: a unexplained variations after fitting the model; b lrt= likelihood ratio test; c * reference group; d se = standard error; dr = deviance reduction; df = degrees of freedom; pr = probability of a value χ2 exceeding the deviance reduction; χ2 = chi square; als = angular leaf spot. some independent variables, namely district (χ2 = 29.37, 5df), altitude (χ2 = 4.07, 1df) and field size (χ2 = 3.85, 1df) were significantly (p ≤ 0.05) associated with disease severity when first entered to the model (table 6). however, field size lost its importance when entered last in to the model. district was the most significantly associated variable with severity when entered first and last into the model (χ2 = 29.37 and 24.49, 5df). variables including cropping system (χ2 = 0.25, 1df), growth stage (χ2= 1.62, 2df), cropping pattern (χ2 = 2.88, 1df), sowing date (χ2 = 2.26, 1df), plant density (χ2 = 0.41, 1df) and weed density (χ2 = 0.9, 1df) were not significantly (p ≤ 0.05) associated with severity when entered first and last in to the model. this implies that the effects of sowing date, cropping system, cropping pattern, growth stage, weed and crop density on disease severity may vary with misganaw et al. east african journal of sciences volume 13 (1) 51-64 60 agro-ecology, pathosystem and weather factors. on the other hand, district (χ2 = 24.49, 5df) and altitude (χ2 = 6.11, 1df) maintained their association with severity when entered into reduced variable model. the influencing magnitude of altitude on severity highly increased, while the contribution of district to severity decreased in the reduced variable model (table 6). classes of district and altitude were tested in reduced multiple variable model and their parameter and standard error resulted from reduced regression analysis are shown in table 8. the probability of als severity >85% was highly associated to at higher altitude range (>1718m.a.s.l), harc and awassa zuria districts. low severity had high association to lower altitude ranges, bolloso sore and kerisa districts. there were one and half, two, three and four times higher probabilities of association for the occurrence of high severity in harc than awassa zuria, bako tibe, jarc and kerisa, respectively. on the other hand, the probability of occurrence of high severity in semi-low land areas (altitude ≤1718m.a.s.l) was two and half times lower than semi-high land areas (altitude >1718m.as.l). 4. discussion angular leaf spot was prevalent and widely distributed in all common bean growing fields studied regardless of agro-ecology, altitude, field size, sowing date, cropping system, growth stage as well as weed and crop density. the distribution of this destructive disease in all surveyed areas might be either due to the environmental conditions which favor development of the disease and/or due to presence of diversified causative pathogens across different common bean growing areas. comparatively, higher mean disease incidence and severity were observed in jarc and harc that might be partly due to fluctuating high temperatures and relative humidity, which favor the disease development under field condition together with other epidemic factors. angular leaf spot was reported to be the important disease in bean growing areas characterized by a humid climate, high temperature and high rainfall in ethiopia (habtu et al., 1996). variation in disease prevalence and intensity across locations would be attributed to prevailing environmental conditions and crop management practices, which is similarly reported by sceuemann et al. (2012). furthermore, the high mean disease intensity observed in all agro-ecologies might be associated to the poor cultural practices adopted by smallholder farmers in the area including use of poor quality farmer-saved seed sources, lack of crop rotation and poor management practices exacerbated by conducive environment conditions for disease development (njingulula, 2014; kijana et al., 2017). dependency on own seed sources, as observed in the studied areas, could result in the build-up of inoculum and significantly contribute to the development disease epidemics (wachenje, 2002; mwangombe et al., 2007). the amount of inoculum present in each farm, level of field sanitation and type of cropping system employed might also had an influence on overall disease distribution and epidemics (stenglein et al., 2003, mwangombe et al., 2007). the findings of the study revealed that mean disease intensity was more pronounced in semi-high land areas (altitude >1718m.a.s.l). this might be partly due to the high rainfall and relative humidity common in the areas, which could favor als infection and epidemic development. mwangombe et al. (2007) also obtained high disease incidence in altitude ranges of 1601-2000 m.a.s.l, which was lower in areas above 2000 m.a.s.l. due to the cool temperature in high altitude areas that may inhibit als developments. in contrast, kijana et al. (2017) reported that als severity was high in the higher altitudes than lower altitude areas. similarly, ddamulira et al. (2014) found slightly high disease incidence and low severity observed in high altitude areas of uganda, which are characterized by cold conditions. this indicated that cold temperatures alone might not be the only factor contributing to als epidemics, but bean cultivar type grown may also influence disease incidence. cropping system showed unavoidable effects on als disease epidemics as mean disease incidence reduced by 13.47% in intercropped fields. the effects of intercropping on disease incidence might be due to an increase in spatial distance between host plants, which might inhibit free dispersal of pathogen and suppress weeds responsible for the build-up of high humidity under the canopy. there are also several studies with regard to the inhibition potential of intercrops against different pathogens in various pathosystems (chemeda, 2003; altieri et al., 2005; samuel et al., 2008b; habtamu et al., 2015). however, intercropping did not show reduction effects on disease severity, which might imply that intercropping could not be effective to reduce disease epidemics once the disease has established on host plants. chemeda and jonathan (2001) also observed higher maize rust epidemics in maize-sorghum intercropped fields than in sole cropped fields. the effects of intercropping on disease epidemics also depend on the temperature and relative humidity requirements of pathogens (boudreau and mundt, 1992; chemeda, 1996). cropping pattern also showed strong association with als disease epidemics. mean disease incidence was 10.84% higher in row planted fields than broadcasted. this could be due to bean association with component crops in intercropping systems as majority of broadcasted fields were observed intercropped with other crops. on the other hand, the effects of cropping pattern on disease epidemiology may vary with pathosystem, other cropping practice, geographic area and weather factors too. there was a variation with regard to the influence of crop growth stage on the disease epidemics. mean disease incidence at maturity stage was 19.98% and 4.11% greater than flowering and pod filling growth stages, respectively. on the other hand, mean disease severity at pod filling stages was higher than flowering and maturity growth misganaw et al. common bean angular leaf spot (phaeoisariopsis griseola) with biophysical factors 61 stages even though there was a minimum variation among them. this might be due to defoliation of early infected leaves before reaching maturity growth stage. if the conditions are conducive for als development, it may result in premature defoliation (saettler, 1991). the reduction effects of disease incidence at flowering stage might partly associated with cropping system as majority of intercropping fields were at flowering growth stages. the effects of growth stage on disease severity might explain the fact that as far as the environmental condition is conducive and once the disease infects the plant, it might damage the whole growth stages during the growing season. in addition, a change in agronomic practices and climate might have contributed to development of new aggressive strain which may lead to devastation of the crop. moreover, the influence of growth stage on disease epidemics might vary with seasonal effects, sowing date, cultivar used and many other epidemic factors. reports of ciat (2010) showed that als is more prominent during late flowering and pod formation stages. a study by kijana et al. (2017) also found significant association between disease intensity and common bean growth stages in which angular leaf spot disease was higher in pod filling stage than flowering and pre-podding stages. in contrast, samuel et al. (2008b) found higher disease intensity of faba bean chocolate spot at flowering stage than pod filling stage and associated to defoliation or aging of already infected leaves of the plant at pod filling crop growth stage. crop and weed density had strong association to disease incidence. the mean disease incidence was higher in highly weedy farms as well as in densely populated beans than weed free and sparsely populated beans. high weed infestation could reduce crop vigor and promote disease development through competition for available resources that render crops susceptible to both foliar and soil-borne pathogens. in addition to competition for resources, weed modifies the microclimate and increase canopy humidity that would assist epidemic development (samuel et al., 2008b; eshetu et al., 2013). dense population could also increase relative humidity and competition for similar resources, which in turn could make host plants weak and susceptible for the pathogen to enhance the development of high disease incidence. low plant population is also supposed to decrease canopy enclosure and may increase free circulation of air under the crop canopy. free circulation of air might reduce damp sites responsible for high humidity build-up. similarly, habtu et al. (1996) reported that high plant densities are associated with high disease development and high population density favor easy spread of bacterial blight and anthracnose propagules between crops. a study by samuel et al. (2008b) also found that a higher number of faba bean was infected with chocolate spot in densely populated fields than in sparsely populated faba beans. the logistic regression model revealed that district, cropping system, growth stages, sowing date and weed density were significantly associated with als incidence individually or in combination. variables like altitude and cropping pattern were not significantly associated with incidence. the insignificant association of altitude and disease incidence might be partly due to the suitable environmental conditions favouring als development and/or there might be variable pathogen races in the surveyed areas, which enable the pathogen to widely infect the host regardless of elevation differences. in addition, the survey was made during typical bean growing period with wet and dry weather conditions which is conducive for als development. if environmental conditions are known to favor disease development, there might be high disease incidence and severity even in low altitude areas ranging from 1000 to 1200 m.a.s.l (correa-victoria et al., 1989; ddamulira et al., 2014). angular leaf spot development is stimulated under temperature conditions of 18-22 °c and relative humidity of 70-100%. such conditions are experienced in low altitude bean growing areas (stenglein et al., 2003; mugisha, 2008). higher temperatures, with an optimum for disease development between 24 and 28 °c, favored the infection and colonization by p. griseola as well as als development (bassanezi et al., 1998). the probability of occurrence of high disease incidence was triple times in early planting than late planting. early sowing might be associated with high infestation of weed that may modify the micro-environment to humid in planting fields, which could favor the germination of spores, growth and developments of disease. in addition, early sown common bean genotypes were at pod filling to physiological maturity stages in which als disease expected to be high. according to habtu et al. (1996), sowing date had a clear effect on disease epidemics. a study by essubalew et al. (2015) also revealed that early bean sowing increased als incidence in which early planting expose plants for long period of rainfall, leaf wetness, pathogen and high humidity. similarly, als spreads and develops rapidly if production conditions of moderate temperature, prolonged periods of wet weather or high humidity alternates with warm weather (celetti et al., 2006). in addition, most of the surveyed common bean fields were at pod filling stage at which the crop is expected to be susceptible to the pathogen and the development of als is supposed to be high keeping the effects of the other epidemic factors constant. with regard to weed population, high probability of disease incidence was highly associated with high weed density. weed population could modify micro-environment under the crop canopy, which might favor disease development. low weed density was highly associated with low bacterial blight, whereas medium and high weed population were strongly associated with high bacterial blight (habtu et al., 1996). several studies also indicated that weedy farms positively associated with high disease parameters in different host-pathogen pathosystems (zewdie et al., 2007; samuel et al., 2008; eshetu et al., 2013). the logistic model misganaw et al. east african journal of sciences volume 13 (1) 51-64 62 quantified the relative importance of independent variables implying that als epidemics was the function of these variables either to increase or decrease disease epidemics. 5. conclusions results of the study identified that angular leaf spot was widely distributed and high mean disease incidence and severity was observed in all agro-ecologies surveyed. als intensity varied among districts and research centers, altitude, field size, sowing date, cropping system, crop growth stages as well as weed and crop density. these independent variables were confirmed as important to the developments of common bean als. results from regression analysis also indicated that the independent variables have strong association with disease epidemics and implying appropriate interventions are needed to perform through creating awareness for growers about disease causative agent characteristics, survival, dispersal as well as possible management options to reduce effects below economic injury level. in addition, proper cultural practices such as using of quality seed, practicing crop rotation and intercropping should be adopted by growers to minimize the associated inoculum load and als epidemics. likewise, maintaining optimum crop density and managing weeds below economic damaging level also should be included in disease management strategies. improving locally and commercially available common bean varieties is highly desirable to reduce sensitivity of the crop to the pathogen. 6. acknowledgements the study was financed by the ministry of education (moe), ethiopia. we are very grateful to melkassa agricultural research center for providing transport and other facilities during the survey period. the authors acknowledge mr. birhanu sisay, mr. nigus gurims and mr. abrham atile for their contribution to the efforts of data collection, data analysis and study map generation. common bean growers and developmental agents in the study areas are sincerely appreciated for their keen interest and collaboration in the survey. 7. references allen, d. j. 1983. the pathology of tropical food legumes: disease resistance in crop improvement. john wiley and sons, new york, 413p. allorent, d. and savary, s. 2005. epidemiological characteristics of angular leaf spot of bean: a systems analysis. european journal of plant pathology, 113(4): 329-341. altieri, m.a., ponti, l. and nicholls, c. 2005. enhanced pest management through soil health: toward a below ground habitat management strategy. biodynamics, 3340. bassanezi, b., amorim, l., bergamin f., a. and hau, b. 1998. effects of bean line pattern mosaic virus on the monocyclic components of rust and angular leaf spot of phaseolus bean at different temperatures. plant pathology, 47: 289-298. beebe, e.s., rao, m.i., devi, j.m. and polania, j. 2014. common beans, biodiversity, and multiple stresses: challenges of drought resistance in tropical soils. crop and pasture science, 65(7): 667-675. boudreau, m.a. and mundt, c.c. 1992. mechanisms of alteration in bean rust epidemiology due to intercropping with maize. phytopathology, 82: 10511060. celetti, m.j., melzer, m.s. and boland, g.j. 2006. angular leaf spot on snap beans. factsheet order no. 06-047. ministry of agriculture, food and rural affairs. ontario, canada. accessed from http://www.omafra.gov.on.ca/english/crops/facts/ 06-047.pdf on 04 february 2018. chemeda fininsa and jonathan yuen. 2001. association of maize rust and leaf blight epidemics with cropping systems in hararghe highlands, eastern ethiopia. crop protection, 20: 669-678 chemeda fininsa.1996. effect of intercropping bean with maize on bean common bacterial blight and rust diseases. international journal of pest management, 42 (1): 51-54. chemeda fininsa. 2003. relation between common bacterial blight severity and bean yield loss in pure stand and bean-maize intercropping systems. international journal of pest management, 49: 177-185. ciat (centro internacional de agricultura tropical). 2010. bean disease and pest identification and management. kampala, uganda. no. 371. correa-victoria, f.j., pastor-corrales, m.a. and saettler, a.w. 1989. angular leaf spot. in: schwarts, h.f. and pastor-corrales, m.a. 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(ed.) compendium of bean diseases aps press, st paul, mn: 15-16 samuel sahile, seid ahmed, chemeda fininsa, mathew m.a. and parshotam, k.s. 2008a. effect of mixed cropping and fungicides on chocolate spot (botrytis fabae) of faba bean (vicia faba) in ethiopia. crop protection, 27: 275-282. samuel sahile, seid ahmed, chemeda fininsa, mathew m.a. and parshotam, k.s. 2008b. survey of chocolate spot (botrytis fabae) disease of faba bean (vicia faba l.) and assessment of factors influencing disease epidemics in northern ethiopia. crop protection, 27: 1457-1463. scheuermann, k.k., raimondi, j.v., marschalek, r., de andrade, a. and wickert, e. 2012. magnaporthe oryzae genetic diversity and its outcomes on the search for durable resistance. caliskan, m. (ed.). isbn 978-95351-01574. the molecular basis of plant genetic diversity, chapter, 15: 331-356. singh, s.p. and schwartz, h.f. 2010. breeding common bean for resistance to diseases. crop science, 50: 22002223. singh. 2007. revised introductory plant pathology. stenglein s., ploper, l.d., vizgarra, o. and balatt, p. 2003. angular leaf spot: a disease caused by the fungus phaeoisariopsis griseola (sacc.) ferraris on phaseolus vulgaris l. advances of applied microbiology, 52: 209-243. voysest, o. 2000. mejoramientogenetico del frijol (phaseolus vulgaris l.). ciat, colombia: 195p. wachenje, c.w. 2002. bean production constraints, bean seed quality and effect of intercropping on floury leaf spot disease and yields in taita taveta district, kenya. msc. thesis, university of nairobi: 117p. wheeler, b.e.j.1969. an introduction to plant diseases. wiley, london: 347p. yesuf, m. 2005. seed borne nature of colletotrichum lindemuthianum and its epidemic on common beans in the major bean growing areas of ethiopia. a phd thesis in tropical agriculture. graduate school, kasetsart university. yuen, j., twengstrom, e. and sigvald, r. 1996. calibration and verification of risk algorithms using logistic regression. european journal of plant pathology, 102: 847-854. http://faostat3.fao.org/faostat-gateway/ http://faostat.fao.org/site/567/default.aspx#ancor misganaw et al. east african journal of sciences volume 13 (1) 51-64 64 zewde, tamire., chemeda fininsa., sakhuja, p.k. and seid, ahmed. 2007. association of white rot (sclerotium cepivorum) of garlic with environmental factors and cultural practice in the north shewa highlands of ethiopia. crop protection, 26: 1566-1573. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2019) volume 13 (2) 135-144 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: zelalembekeko@yaoo.com attribution-non-commercial 4.0 international license. distribution and importance of common rust of maize (puccinia sorghi schw.) in hararghe highlands, eastern ethiopia zelalem bekeko school of plant sciences, haramaya university, p.o. box 138, dire dawa, ethiopia abstract: maize is an important staple crop in ethiopia. however, its production is threatened by a number of diseases among which common rust caused by puccinia sorghi, is the most destructive foliar disease of the crop in the country. data are useful to gain insight into the occurrence, distribution, relative importance of plant diseases and the association of these diseases with cropping systems, environmental factors and cultural practices. therefore, field surveys were conducted during 2013 and 2014 main cropping seasons in hararghe highlands, ethiopia to investigate the prevalence, intensity and importance of common rust of maize. in both years, a total of 230 maize fields were surveyed in eastern and western hararghe zones. in order to incorporate different altitudinal ranges and analyze the survey data, a three-stage nested design was used. among the surveyed maize fields, 85% of them were infested with the disease. the mean disease incidence in two years ranged from 75% in the eastern hararghe to 100% in the western hararghe zone and the severity ranged from 25% to 65%, respectively. combined analysis over the years also showed that the mean incidence and severity of common rust of maize were significantly associated with the zones (χ2=15, df=1, p=0.0001). the highest mean common rust incidence (95%) and severity (55%) were recorded for boke, chiro, oda bultum and tullo districts in the western hararghe zone whilst deder, chelenko, haramaya and kombolcha districts of the eastern hararghe zone had the lowest mean incidence (45%) and severity (25%) scores, respectively. higher epidemic frequency of the disease was also associated with intermediate and humid areas (tullo, boke and oda bultum districts) (χ2=30, df=7, p=0.0001). the prevalence, intensity, and importance of the disease was also correlated with cropping systems, altitude, weather variables and varieties used during the survey time (r=0.55; r=0.45; r=0.25 and r=0.50), respectively. it is, thus, concluded, that common rust (puccinia sorghi schw.) is the most widely distributed and important foliar disease of maize in hararghe highlands. keywords: ecology; epidemiology; eastern hararghe zone; incidence; prevalence; severity; western hararghe zone 1. introduction maize (zea mays l.) is one of the most important cereal crops in larger parts of the world including ethiopia (abate et al., 2015; fao, 2017). in ethiopia it is a staple food crop and one of the main sources of calories in major maize producing regions. it is cultivated on about 2.135 million hectares of land in the country (csa, 2018). the national average yield of maize under subsistence production is about 3665 kg/ha (csa, 2018). this is too much below the world’s average yield (tilahun et al., 2017). this low yield is attributed to foliar diseases and insect pests such as stalk borers (dagne et al., 2008; girma et al., 2015; zelalem et al., 2018). in ethiopia, the production of maize is threatened by a number of biotic and abiotic factors. among the biotic factors, common rust caused by puccinia sorghi, is the most destructive foliar disease of maize in the country. in maize growing regions of ethiopia, the disease has become a potential threat to maize cultivation (tewabech et al., 2012). it appears from the early stages of maize growth and if proper management is not adopted in time, it damages the plant causing higher yield losses (assefa et al., 1993; netsanet, 2005; daniel, 2008; tewabech et al., 2012). common rust causes extensive yellowing and premature desiccation of maize foliage, resulting in leaf necrosis, and complete destruction of the photosynthetic areas. in extreme cases, heavy rust infestations may result in stunting, incomplete ear tip fill and pustules on ear husks, reducing marketability and yield. the disease occurs in several maize producing areas in the country, resulting in grain yield reductions up to 23% (fininsa, 2001) and 60.5% yield loss was also noted for susceptible cultivars such as cml202 (deyle et al., 2012). common rust of maize caused a yield loss of 12-60% (utpal et al., 2012) in asia and occurs in all maize growing areas of the world (bello et al., 2012; wang et al., 2014). similarly, in eastern ethiopia, netsanet (2005) reported a disease severity of up to 35% and relative yield loss of 29% in unsprayed plots due to this pathogen. currently, common rust has also become the most important threat to maize production in maize bekeko east african journal of sciences volume 13 (2) 134-144 136 growing areas of ethiopia causing significant yield losses (tewabech et al., 2012). in developing countries like ethiopia, one of the bottlenecks, which are responsible for lowering the yielding potential of maize, is the usage of varieties with inferior genes, which are susceptible to diseases, insects, weeds, low yielding and inferior quality. in addition, lack of adequate investment and skilled manpower to improve varieties for high yield and disease resistance as well as, diminishing land and water resources and environmental stresses are reducing yielding potential of the crop (shiferaw et al., 2014). in hararghe highlands of eastern ethiopia, where maize is grown among the major cereals, in the high rainfall areas such as (chiro, doba, tullo, mesela, gemechis, kuni, boke, habro, darolabu, deder, chelenko, haramaya and kombolcha) foliar diseases and soil fertility depletion are major problems constraining crop productivity. intercropping is widely used in these areas by combining maize or sorghum with the perennial narcotic crop like khat (catha edulis forsk) and common bean which further exposes the soil to rampant nutrient depletion and high disease epidemics leading to poor crop yield (heluf et al., 1999; fininsa, 2001; ararsa, 2012). in this area, maize is grown on soils devoid of basic crop nutrients being exposed to foliar diseases such as common rust. hence, the genetic potential of hybrids deployed in this region will not be fully exploited (bekeko, 2013; bekeko, 2014). maize yield is highly variable in rainfed environments of ethiopia and it is still very low (often less than 4 t/ha., csa, 2018). therefore, developing and deploying maize varieties combining high yield potential and tolerance to major foliar diseases, is vital to reduce the risks associated with planting under rainfed conditions in the highlands of the country (brummer et al., 2011). most of the maize varieties growing in eastern ethiopia are prone to the disease, which inflicts heavy yield losses under favorable weather conditions (bekeko, 2014; tilahun et al., 2017; zelalem et al., 2018). most of the local cultivars, composites and novel hybrid maize varieties growing in this area showed susceptibility to this disease which can potentially affect the food security of the community. previous surveys in other regions of ethiopia have examined the association of the disease with cropping systems and some cultural practices. jeger (2004) and madden et al. (2007) indicated the importance of the knowledge of epidemiological features of plant diseases in providing useful information for understanding the biology of their causal agents, and its role as the basis for the establishment, planning and monitoring of effective disease management strategies. understanding disease epidemiology as it is affected by different variables is also useful to design ecologically sustainable disease management tactics and strategies (madden et al., 2007). survey data are useful to gain insight into the occurrence, distribution, relative importance of plant diseases and the association of these diseases with cropping systems, environmental factors and cultural practices (rusuka et al., 1997). however, little documented information is available to gain insights into occurrence, distribution, and the relative importance of maize rust in the eastern highlands of ethiopia. this research was, therefore, conducted to determine the prevalence and relative importance of common rust of maize in hararghe highlands, eastern ethiopia. 2. materials and methods 2.1. description of the survey procedures field surveys were conducted in different agroecological zones of eastern ethiopia (eastern and western hararghe zones) during the 2013 and 2014 main cropping seasons. the survey route followed major roads to towns and localities in each zone. a total of 230 farmers’ fields in eight districts were assessed for the prevalence, intensity and importance of common rust of maize. fields were randomly selected at the interval of 5-10 km along the main and accessible rural roads. within selected fields, three quadrants (4 m * 4 m) diagonally spaced about 10 m apart were sampled. all plants in each quadrant were used as sampling units. when necessary, the sample size (the number of observed fields per district) was adjusted to suit the crop distribution. similarly, the sample units (the number of quadrants) were adjusted to suit the field size. all of the sampled fields belonged to smallholder farmers, research farms and private investors. each field was visited once in each of the two years during which the survey was conducted. bekeko prevalence and importance of common rust of maize 137 fig.1: geographic map of the study area 2.2. prevalence, incidence and severity of common rust of maize the survey covered the most important maize growing districts in eastern and western hararghe zones with frequent intensity of the work pauses at different intervals depending on the variability of fields in terms of altitude and cropping systems. size of the survey site and availability and accessibility of maize fields was given due consideration in deciding where to stop and intensify the work on survey routes. disease prevalence was assessed by determining the number of fields where common rust of maize was recorded in relation to the number of fields sampled in different localities. disease assessment was made on 40 randomly selected plants in each field. common rust of maize incidence was assessed as: x100 inspectedplant of no. total ratings numerical all of sum incidence disease  disease severity: common rust of maize severity was rated according to dey et al. (2012) using 1-5 scales: 1 = no symptoms; 2 = moderate lesion development below the leaf subtending the ear; 3 = heavy lesion development on and below the leaf subtending the ear with a few lesions above it; 4 = severe lesion development on all but the uppermost leaves, which may have a few lesions; and 5 = all leaves dead. the survey was conducted at the stages of booting and physiological maturity stages to assess and rate the average leaf area of maize covered by the common rust of maize pustules from 40 randomly selected diseased plants per field. the numerical rating was converted to percentage severity index (psi) using the following equation suggested by wheeler (1969): x100 scaleon score disease maximum × rated of no. total ratings numerical all of sum psi  2.3. data analysis data was first checked for various anova assumptions. the mean incidence and severity data were calculated for each district. the field survey data for common rust of maize (incidence and severity) was analyzed using a three-stage nested design. mean common rust of maize incidence and severity of each zone were used to make comparison among the surveyed districts within two zones. chi square test was employed to determine the distribution of the disease and correlation analysis was made to determine the association of common rust of maize epidemics, incidence and severity with different districts, weather variables, varieties and cropping systems within zones. all the statistical analyses were carried out using sas v bekeko east african journal of sciences volume 13 (2) 134-144 138 9.2 and the least significant difference (lsd) test was used for mean comparison (gomez, 1984). 3. results and discussion 3.1. prevalence and intensity of common rust of maize analysis of the results of disease intensity indicated that common rust of maize was prevalent in all maize producing districts of the surveyed districts in the region. the lowest mean incidence is74.25% for kombolcha and the highest mean incidence is 95.25 % for boke indicating the disease was the most destructive during the survey seasons (table 1). the highest prevalence of common maize rust (89.3%) was recorded for tullo district, followed by boke, oda bultum and chiro districts of the western hararghe zone which had severity of 95%, 90% and 85% respectively, while the lowest prevalence of common rust of maize (55%) was recorded for deder, chelenko, haramaya and kombolcha districts, east hararghe zone (table 1). table 1. incidence and severity (mean values) of common rust of maize (puccinia sorghi) on maize at hararghe highlands, under field conditions (2013 and 2014 data). location altitude (m.a.s.l) mean of crm incidence (%) mean of crm severity (%) chiro 1850 2300 90.00 65.10 kuni 2150 2460 85.77 70.40 tullo 1850 2200 89.34 75.57 boke 16502300 95.25 65.25 deder 17002150 80.50 55.50 chelenko 17502000 75.00 45.85 haramaya 18502200 82.50 35.50 kombolcha 18502300 74.25 40.50 mean 84.13 56.70 cv 9.50 13.25 note: m.a.s.l = meters above seal level; crm = common rust of maize in general, common rust of maize was the most prevalent (85%) in all of the 230 maize farms surveyed from eastern and western hararghe zones in 2013 and 2014. the higher prevalence of common rust of maize during the survey seasons in all assessed districts could be attributed to the favorable environmental conditions coupled with cultivation of susceptible maize cultivars worsened the problem to maximum. a common rust of maize epidemics is favored by high rainfall and relative humidity, with warm temperatures, and the presence of larger amounts of inoculums in the region (tewabech et al., 1993). the other most possible reasons for the variation in common rust distribution in the region could be the variability in weather conditions. as a result, producers can have an impact on the prevalence and intensity of this disease by deciding from a number of management strategies including host plant resistance, cultural practices (adjusting planting date, plant density, crop rotation and tillage practices) and careful use of foliarapplied fungicides (fininsa, 2001). the previous study of tewabech et al. (2012) reported that the presence of increased prevalence of common rust in the major maize producing regions of western, southern, northwestern, eastern, southeastern parts of ethiopia. according to the report, common rust of maize has become the principal maize disease since 1993 in ethiopia. 3.2. incidence and severity of common rust of maize across zones analysis of the result of incidence and severity data revealed that common rust of maize was the most prevalent in the entire surveyed zones but with varying intensity. table 2. distribution of common rust of maize in wester hararghe zone (mean values) in 2013 and 2014 main cropping seasons. distribution level boke oda bultum tullo χ2 test n % n % n % high 92 94.8 85 100 92 93.9 medium 5 5.2 0 0 6 6.1 5.695* low 0 0 0 0 0 0 over all sample 97 100 85 100 98 100 bekeko prevalence and importance of common rust of maize 139 the mean incidence and severity of the disease varied significantly from zone to zone (tables 2). there was a statistically significant (p<0.001) difference between the zones in terms of incidence of the disease (table 2). the mean incidence in the two zones ranged from 57.6-65.6% (table 3). it was also revealed that the disease occurred in the entire assessed districts having different agro-ecologies and was the most prevalent in all the surveyed maize farms. combined analysis over the years also revealed that the mean incidence and severity of the disease significantly varied from district to district with a wider frequency of distribution (χ2=16.5, df=8). higher incidence of common rust of maize was observed for boke (95%) and tullo (94%) followed by oda bultum (82%) and chiro (75%) districts. the wider distribution and the higher incidence of the disease in western hararghe zone could be attributed to the occurrence of intermediate rainfall, variation in altitude, adopted cropping systems and varieties planted by farmers and lack of crop rotation in the zone that are favorable for the growth and development of the fungus leading to its sporadic epidemics (netsanet et al., 2005; mohammed et al., 2014). table 3. incidence and severity of common rust of maize (puccinia sorghi) on farmer’s field in eastern and western hararghe zones 2013 and 2014 main cropping seasons in major maize producing districts. zone location altitude (m.a.s.l) incidence of crm (%) severity of crm (%) july to august sept to october western hararghe chrio 1470 20 8 1500 15 10 1580 15 10 1880 35 30 2300 45 35 1900 35 30 1480 20 10 1750 15 10 mean 25 17.8 kuni 1750 25 15 2225 75 58 2000 70 55 2100 70 50 2050 72 45 9000 65 45 1870 55 35 1800 50 35 mean 60.25 42.25 eastern hararghe deder 1900 55 35 1920 65 50 1950 65 50 2250 75 50 2400 80 70 2200 70 75 2000 70 58 2250 75 50 mean 69.38 54.75 chelenko 1900 35 25 2050 40 30 2350 85 75 2250 80 75 2000 70 60 2000 50 35 1860 45 25 1960 45 25 2125 55 25 2100 55 20 1700 35 15 mean 74.38 51.25 bekeko east african journal of sciences volume 13 (2) 134-144 140 danson et al. (2008) reported that increased incidence of common rust of maize in africa was associated with weather variables, cropping systems, cultural practices such as reduced tillage, continuous cultivation of maize, and use of susceptible maize cultivars. according to the authors, conservation tillage leaves infested residue from previous crop on the soil surface that increases initial inoculums of the disease attached to the green bridge which serve as the over wintering of the parasite (obligate fungi). moreover, increasing crop residue on the soil proportionally increases the amount of primary inoculum sources of the pathogen (dey et al., 2012). fig 2. infested maize fields with common rust of maize (puccinia sorghi) at chiro, west hararghe, photo taken by the author, 2013. fig 3: infested maize fields with common rust of maize (puccinia sorghi) at tullo, west hararghe zone, photo taken by the author, 2013. fig 4. infected maize fields with common rust of maize (puccinia sorghi) at deder east hararghe zone, photo taken by the author, 2014 statistically there was also a significant (p<0.001) difference in severity of the disease between the two zones. the mean severity of common rust of maize in the zones ranged from 35 to 75% (table 3). severity of common rust of maize was also higher at boke (75%) and tullo (67%) followed by chiro (52%) districts whereas the lowest severity was recorded for komobolch (25%), in 2013. this result revealed that higher variations in disease incidence and severity were recorded for the two zones (table 3). this suggests that variation in existing weather condition, cultural practices, lack of crop rotation and difference in genetic background of maize genotype planted by farmers in the zones contributed for the variation in the development of the fungus and the disease, respectively. therefore, farmers can have different options to manage this disease based on the variation in incidence and severity of common rust of maize by choosing from a number of management techniques including cultural practices, which include crop rotations, soil cultivation, intercropping with common bean, resistant host genotypes, use of short-season maize varieties, regulating planting time and plant density and use of fungicides. 3.3. incidence and severity of common rust of maize across districts within zones the survey result on the prevalence, intensity and importance of common rust of maize in maize growing districts of separate zones of eastern ethiopia were presented in table 3. common rust of maize was prevalent in all the assessed areas of the two zones. both incidence of the disease varied significantly across the districts within two zones of different agroecological at chiro (fig. 2) and tullo (fig. 3) and at deder (fig. 4) east hararghe zone; and the severity of the disease conditions were shown in tables 4. the mean incidence of common rust of maize in the different districts ranged from 55% to 100%. statistically, there was highly significant (p < 0.001) difference among districts in terms of common rust of maize incidence and severity (tables 3). the seriousness of common rust of maize was elucidated by the damage (severity) demonstrated on the plant. similarly, a survey conducted by fininsa and yuen (2001) in 280 farmers' fields in 10 districts of different cropping systems in the hararghe highlands including sole maize, maize-bean, maize-bean-sorghum and maize-bean-other has shown the difference in occurrence and distribution of common maize rust of maize in studied geographical area. in their conclusion bekeko prevalence and importance of common rust of maize 141 they reported mean rust incidences of 69–75% and severities of 48–57% in all the surveyed cropping systems. this is in agreement with the present finding, which depicted higher values of common rust incidence and severity in this investigation (table 4). table 4. distribution of common rust of maize in eastern hararghe zone (mean values). distribution level deder chelenko haramaya χ2 test no. % no. % no. % high 72 82.75 85 100 92 93.9 medium 15 17.24 0 0 6 6.1 12.50* low 0 0 0 0 0 0 over all sample 87 99.9 85 100 98 100 generally, the overall severity of the disease was 65% (table 4). the highest frequency of epidemic occurrences of this disease was more associated with areas which have predominant and intermediate relative humidity (tullo, kuni and oda roba (χ2=23.5, df=4)) followed by areas which have an intermediate annual rainfall amounts and warmer temperatures. the prevalence and intensity of the disease was also associated with the existing cropping systems, weather variables and varieties used during the survey time (r=0.55; r=0.45; r=0.25 and r= 0.50), respectively. from this study, it was also observed that the maize common rust is the most widely distributed and important foliar disease of maize in the hararghe highlands significantly limiting maize yield. in view of the fact that, all of the surveyed areas, common rust of maize was recorded in all districts, thus common rust of maize was present in all areas of the assessed districts. earlier results of various surveys conducted in most maize growing regions of ethiopia indicated that the disease has a wide distribution and significant impact on maize yield reduction on both local and improved varieties (tewabech et al., 2012; fininsa, 2001). according to worku et al. (2012), some of the released hybrid maize varieties, bh-660, bh-661 and phb-30h83 were found to be relatively tolerant to common rust of maize. this disease has also been observed in maize seed multiplication sites at eastern shewa, jimma, east wollega and sidama zones where monocropping is practiced using the recently released maize varieties. several reports, from the u.s.a. (iowa), brazil, kenya, ethiopia showed the epidemics of common rust of maize is severe under monoculture (sole maize), with no rotation practices and minimum tillage practices (fininsa and yuen, 2001; doyel et al., 2012). it was apparent that maize is grown over a large area of eastern and southeastern parts of ethiopia where this disease dominantly exists. 3.4. relationship between weather variables, common rust incidence and severity the relationship between disease development and weather variables was established using correlation analysis to look for the effect of individual variable on disease development. correlations between weather variables and common rust of maize (crm) incidence and severity were determined (table 5). the result revealed that common rust of maize incidence and severity had negative and insignificant correlation with altitude (r = 0.55 and r = -0.850, respectively). there was strong positive correlation between rainfall and mean common rust of maize incidence and severity (r = 0.25 and r = 0.55, respectively). rainfall during the actual maize production seasons of each surveyed area in 2013 and 2014 was also strongly correlated but insignificantly with both common rust of maize incidence and severity. on the other hand, temperature had insignificant correlation with both disease incidence and severity. this indicated the strong influence of weather condition particularly that of rainfall on common rust of maize development. a strong positive and highly significant correlation (r = 0.85) was also found between disease incidence and severity. in the present survey, conducted in hararghe highlands, eastern ethiopia greater variation in common rusts of maize prevalence, intensity and importance, were observed ranging from mild to severe infections. in this study, all of the surveyed areas showed moderate to severe common rust of maize infection, which usually have, humid or warm temperature and high rainfall. cropping systems such as inter-cropping and use of cultivar mixture are also recognized in reducing disease pressure in positive or negative ways (fininsa and yuen, 2001; jeger, 2004). from the present investigation it was observed that farmers in surveyed region do not apply any specific management practice to control common rust of maize at least intentionally. disease assessment is one of the most challenging tasks in working with plant diseases (madden et al., 2007). a diseased plant or group of diseased plants is often recognized easily once symptoms or signs become visible; however, it is the quantification of the disease that presents the challenge. the assessment of disease incidence (i.e., the number or proportion of diseased plants in a population) is an apparently simple counting task, but is subject to the usual limitations of interpretation related to sample size. the accurate and bekeko east african journal of sciences volume 13 (2) 134-144 142 precise estimation or measurement of disease severity (i.e., the area or proportion of plant tissue that is symptomatic) can be a formidable task because of visual and measurement errors and the need for samples to be representative of the area considered and to be of adequate number (danson et al., 2006; delaney et al., 1998; madden et al., 2007; siniya et al., 2013; bekekoet al., 2013). understanding disease epidemiology as it is affected by different variables is also useful to design ecologically sustainable disease management tactics and strategies. management practices aimed at a reduction of initial inoculum are effective against polycyclic diseases and/or diseases with longer latent periods, especially diseases having multiple hosts (zadoks and schein, 1979). therefore the present study helps in managing this disease in the study area. . table 5. correlation values of common rust of maize incidence and severity with environmental variables in 2013 and 2014 main cropping seasons. variables altitude (m.a.s.l) rainfall(mm) cropping system variety incidence (%) severity (%) altitude (m.a.s.l) 1 rainfall(mm) 0.830 1 cropping system 0.752 0.875 1 variety 0.750 0.550 0.645 1 incidence (%) 0.255 -0.725 -0.540 -0.750 1 severity (%) -0.680 -0.760 -0.565 -0.850 0.975 1 note: m.a.s.l = meters above sea level 5. conclusion the results of this study demonstrated that common rust of maize occurred in all assessed districts of both eastern and western hararghe zones having different agro-ecologies. the highest mean common rust incidence (75.57%) and severity value of (355%) were recorded for boke, chiro, oda bultum and tullo districts in the western hararghe zone whilst deder, chelenko, haramaya and kombolcha districts of the eastern hararghe zone had the lowest mean incidence (45%) and severity (25%) scores, respectively. it is, thus, concluded, that common rust (puccinia sorghi schw.) is the most widely distributed and important foliar disease of maize in hararghe highlands. hence, the information generated from this study may help in understanding and planning the type of management decision to be used in managing the disease in the study area. therefore, it is recommended that use of tolerant and/or resistant varieties and designing an efficient, inexpensive and sustainable management approaches such as intercropping with food legumes, plant density adjustment and use of improved soil fertility management practices against this pathogen is very crucial for sustainable management of the disease in hararghe highlands. 6. acknowledgements this research activity was financed through the haramaya university research grant for academic staffs from 2012 to 2014. the author thanks the office of the vice-president for research affairs of haramaya university for smooth facilitation of the research activities, the farmers of eastern and western hararghe zones and development agents for participating in the field surveys and their assistance in data collection. 7. references abate, t., shiferaw, b., menkir, a., wegary, d., kebede, y., tesfaye, k., kassie, m., bogale, g., tadesse, b. and keno, t. 2015. factors that transformed maize productivity in ethiopia. food security 17:965-81. ararsa, g. 2012. gis based land suitability evaluation for sustainable agricultural development at kuni (sebale) water shade west hararghe zone, oromia. m.sc. thesis mekele university, ethiopia. assefa, t. and tewabech, t. 1993. review of maize disease research in ethiopia. pp. 43-51. in: benti, t. and ransom, j.k. 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(eds.) 2012. meeting the challenges of global climate change and food security through innovatie maize research. proceedings of the third nati onal maize workshop of ethiopia. mexico, df: cimmyt. zadoks, j.c. and schein, a.d. 1979. epidemiology and plant disease management. oxford university press. oxford. p 427. zelalem, b., chemeda f., dagne w., temam h., shimelis h.and belachew a., 2018. combining ability and nature of gene action in maize (zea mays l) inbred lines for resistance to gray leaf spot disease (cercospora zeae maydis) in ethiopia. crop protection 112 (2018) 39–48. bekeko east african journal of sciences volume 13 (2) 134-144 144 zelalem, bekeko, 2014. effect of enriched farmyard manure and inorganic fertilizers on grain yield and harvest index of hybrid maize (bh-140) at chiro, eastern ethiopia. african journal of agricultural research. 9(7), pp.663-669. zelalem, bekeko. 2014. evaluation of enriched farmyard manure and inorganic fertilizers profitability in hybrid maize (bh-140) production at west hararghe zone, eastern ethiopia. journal of genetic and environmental resources conservation vol 1(3):83-89. east african journal of sciences (2019) volume 13 (2) 145-158 _____________________________________________________________________________________________ licensed under a creative commons *corresponding author. e-mail: slmnbkl092@gmail.com attribution-noncommercial 4.0 international license. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) genetic progress for yield and yield components and reaction to bean anthracnose (colletotrichum lindemuthianum) of large-seeded food type common bean (phaseolus vulgaris) in west shoa zone, ethiopia solomon bekele1*, firew mekbib2, gemechu keneni3, and birhanu amsalu4 1 bako agricultural research center, p. o. box 03, bako, ethiopia 2 haramaya university, p.o.box 138, diredawa, ethiopia 3 holeta agricultural research center, p. o. box 31, holeta, ethiopia 4 melkasa agricultural research center, p. o. box 436, melkasa, ethiopia abstract: fourteen common bean (phaseolus vlgaris l.) varieties that were released in ethiopia from 1997 to 2012 were evaluated as large-seeded food type common bean varieties with the specific objectives to: (1) estimate the genetic progress made in 15 years of common bean breeding in ethiopia; (2) assess changes in associated traits in the genetic improvement of common bean varieties released in ethiopia; and (3) assess the reaction of common bean varieties to bean anthracnose [clletotrichum lindemuthianum (sacc. & magnus) briosi & cavara]. the study was conducted at two locations, bako and gute during 2014/2015 main cropping season in a randomized complete block design (rcbd) with three replications. days to 50% flowering (df), days to 90% maturity (dm), grain filling period (gfp), hundred seed weight (hsw), biomass yield (bmy), grain yield per plot (gy), harvest index (hi), biomass production rate (kg/ha/day), seed growth rate (kg/ha/day), grain yield per day (kg/ha/day) and anthracnose (1-9) scale data were collected on plot basis and plant height, number of pods per plant, number of seeds per pod, number of seeds per plant and grain yield per plant data’s were collected on plant basis. statistical data analyses were performed for biomass yield, grain yield, seed weight, harvest index and bean anthracnose severity. combined analysis of variance showed highly significant differences among the common bean varieties and between test environments for hundred seed weight. the vxl interaction of seed weight did not show significant difference among the varieties. regression analysis of mean performance at both environments on year of varietal release showed positive relationship for seed weight (r = 0.08), biomass yield (r = 0.04) and anthracnose disease severity (r = 0.10) but negative relationship for grain yield (r = -0.38), and harvest index (r = -0.37). the highest overall locations mean average of grain yield was 2679.5 kg ha-1 for ayenew and the lowest was 1050.2 kg ha-1 for glp-2, the grand mean being 1806 kg ha-1. the annual rates of genetic progresses were 12.7 kg ha-1 (0.13% ha-1 year1), -48 kg ha-1 (-0.39%), 0.68 g 100 seed-1 year-1 (0.34% 100 seed-1 year-1), -0.004% and 0.39% for biomass yield, grain yield, seed weight, harvest index and anthracnose disease severity, respectively. generally, the grain yield was reduced in the period of genetic improvement, due to the consistent performance of the reference variety gofta. stepwise regression indicated that grain yield day-1 (82.5%) and days to mature (21.8%) explained more for the variation of grain yield; but, seed size (-40.2%) was more important cause for grain yield reduction than bean anthracnose (-9.3%). the yield of large seeded food type common bean varieties were reduced due to anthracnose and its large seeded for the last fifteen years (19972012) of breeding; in future also managing the disease; especially, anthracnose disease will be the crucial and ayenew (26.79.5 kg ha-1), gofta (2627.1 kg ha-1) and fedis (2180.6 kg ha-1) will be recommended for the area. keywords: anthracnose disease severity; canning type; colletotrichum lindemuthianum; common bean; genetic progress; large-seeded; phaseolus vulgaris; relative genetic gain; stepwise regression. 1. introduction common bean (phaseolus vulgaris l., 2n = 22), also referred to as dry bean, is an annual leguminous plant that belongs to the genus phaseolus, with pinnately compound trifoliate large leaves. in ethiopia, it is most likely that the portuguese introduced the crop in the 16th century (wortman, 1998). common bean is grown throughout ethiopia and is increasingly an important commodity in the cropping systems of smallholder producers (the average farm size for smallholder farmers is between 0.25 to 0.5 hectares) for food security and income. common bean has also health benefits being rich in protein content (about 23% for dried shelled beans and about 6% for green beans) and serving as a good source of iron and zinc (both of which are key elements for mental development). the area covered by common bean production in ethiopia was 113,249.95 ha and 244,049.94 ha for white and red common bean respectively with total area of solomon et al. east african journal of sciences volume 13 (2) 145-158 146 357,299.89 ha and total production of about 540,238.94 tons/ha and national average yield was 1600 kg/ha (csa, 2016). common bean is mainly grown in eastern, southern, south western and the rift valley areas of ethiopia (csa, 2016). beans need up to four months of warm weather and are not frost tolerant. they do poorly in very wet or humid tropical climates because of susceptibility to bacterial and fungal diseases. they need well-drained soils with a ph between 6.5 and 7.0 and are sensitive to deficiencies or high levels of minerals in the soil (broughton et. al., 2003). there is a wide range of common bean types grown in ethiopia, including white, mottled, red, and black varieties. the most commercial varieties are pure red and pure white colored beans and these are becoming the most commonly grown types with increasing market demand (ferris and kaganzi, 2008). to support both the growth in domestic and export bean markets, the ethiopian institute of agricultural research (eiar) has developed a range of high yielding, multi-disease resistant bean varieties. they are major sources of proteins in the lowlands where they are consumed as nifro, wasa, shirowat, soup and samosa. currently, according to the ministry of agriculture report on crop variety registered book in 2014, around 50 common bean varieties are under production; additionally, five new varieties (ser 119, ser 125, tatu, waju and ramada) that were released in 2014 are now under production (moa, 2014). common bean production is constrained by several biotic and abiotic environmental stresses. biotic (field and post-harvest pests and plant diseases) and a biotic (drought, excessive rain/flooding, poor soil fertility, heat and cold stressors) factors are known to cause significant reductions in grain yields (wortmann et al., 1998). bean anthracnose [colletotrichum lindemuthianum (sacc. & magnus) briosi & cavara] poses a major constraint on the production of dry bean in ethiopia. bean anthracnose develops early in the growing season and produces brown to black lesions along the veins of the lower leaves. rain spreads the spores of c. lindemuthianum to neighboring plants and further up into the canopy onto the stems and pods, resulting in the formation of brown to black sunken lesions on which the spore-bearing acervuli are formed. a study by tesfaye b (1997) stated that yield loss up to 62.8% due to anthracnose was recorded in ethiopia on susceptible cultivars of common bean like mexican-142, awash-1 and awash melka. yield refers to the mass of product at final harvest, for which dry matter content should be specified. yield potential is the yield of a cultivar when grown in environments to which it is adapted, with nutrients and water non-limiting and with pests, diseases, weeds, lodging, and other stresses effectively controlled. this definition of yield potential is based on the notion that there are yield genes and stress-resistance genes and that a yield potential measurement attempts to measure only the effects of the yield genes. in measuring progress in genetic yield potential, complications can arise as a result of the possibility of interactions between cultivar and growing conditions (evans and fischer, 1999). knowing the information on genetic progress achieved by a crop over time from a breeding program is absolutely essential to develop effective and efficient breeding strategies by assessing the efficiency of past improvement works in genetic yield potential and suggest on future selection direction to facilitate further improvement (waddington et al., 1986; donmez et al., 2001; many investigators did the genetic progress of common bean and they clarify its positive response; but, they don’t did by classifying according to its seed size and my study reveals negative to their response regarding genetic progress. the focus of this genetic progress work has been on the large-seeded food type common bean varieties with the specific objectives to estimate the genetic progress made in improving yield potential of common bean varieties; to assess changes in associated traits in the genetic improvement of common bean varieties released in ethiopia; and assess the reaction of common bean varieties to bean anthracnose in ethiopia. 2. materials and methods 2.1. description of the study area the field experiments were carried out at two locations, i.e. bako and gute, west shoa zone of oromia regional state, located 250 and 316 km, respectively, to west of addis ababa. the weather (temperatures and relative humidity) and edaphic conditions of the test locations are summarized and tabulated hereunder (table 1). 2.2. treatments/experimental materials fourteen large-seeded food type of common bean varieties that released between 1997 and 2012 from different agricultural research centers in different regions of ethiopia were used. seeds of the common bean test varieties were obtained from bako, melkasa, and sirinka agricultural research centers and haramaya university. the detailed descriptions of the common bean varieties used in the experiment are summarized and depicted in a tabular form hereunder (table 2). solomon et al genetic progress and reaction to anthracnose of bean 147 table 1. description of the test locations for geographical position and physic-chemical properties of the soils. parameters locations bako gute geographical position latitude 09o6'n 09o5'30,n longitude 37o09'e 36o42'0'e altitude (m.a.s.l.) 1650 1918 edaphic characters soil type utisols nitosols soil ph 4.8-5.8 4.5-5.5 weather characters minimum temperature (oc) 13.5 25 maximum temperature (oc) 28.5 30 mean temperature (oc) 21.0 27.5 rh (%) 48.4 57.3 annual rainfall (mm) 1067.1 1350 source: meteorological data of bako agricultural research center (2014) table 2. descriptions of the large-seeded food type common bean varieties used in the study at bako and gute, west shoa zone in 2014/15 main cropping season. s.n o. varieties year of release maturity days yield (kg ha-1) crosses/ seed source 1 gofta 1997 79.2 2627.1 hu 2 ayenew 1997 82.8 2679.5 hu 3 melke 1998 85.0 1928.7 cross 14 marc/eiar 4 ibado 2003 82.0 1464.8 sari 5 red kidney 2007 77.7 1473.2 marc/eiar 6 kufanzik 2008 78.8 2079.8 hu 7 loko 2009 84.0 1630.4 barc 8 glp2 2011 81.2 1050.2 marc/eiar 9 morka 2011 85.8 1633.8 marc/eiar 10 hirna 2012 87.3 1455.4 hu 11 hundane 2012 84.8 1825.9 hu 12 babile 2012 82.3 1707.4 hu 13 tinike 2012 85.5 1549.2 hu 14 fedis 2012 85.7 2180.6 hu note: marc = melkasa agricultural research center, eiar = ethiopian institute of agricultural research, hu = haramaya university, barc = bako agricultural research center, sari = sirinka agricultural research institute. 2.3. experimental design and field management the experiments were conducted at bako and gute during the 2014 main cropping season. a plot of 6.4 m2 consisting of 4 rows of 4 m length with 0.4 m spacing between rows was used. a distance of 0.5 m was maintained between plots and 1 m between blocks. a seed rate of 100 kg ha-1 was used; 160 and 40 seeds were administered to each plot and each row, respectively. the two middle rows were used for data collection. the treatments were arranged in a randomized complete block design (rcbd). fertilizer was applied at the rate of 100 kg ha-1 diammonium phosphate (18 kg n ha-1, 46 kg p2o5 kg ha-1 and 0 k) and all other crop management practices were carried out as recommended. 2.4. data collection 2.4.1. collected data on plot basis days to 50% flowering (df): number of days from planting to the date on which 50% of plants on the two middle rows produced at least their first flowers. grain filling period (gfp): the number of days between days to flowering and days to physiological maturity. days to 90% physiological maturity (dm): the number of days from planting to the stage when 90% of the plants in a plot have reached physiological maturity, i.e., the stage at which pods lost their pigmentation and began to dry. biomass yield (bmy): determined by weighing the total air dried above ground biomass yield of plants in the two middle rows. hundred seed weight (hsw): weight of 100 seeds were counted from each plot and weighted. grain yield per plot (gy): grain yield in kilogram of plants from the two middle rows and adjusted to 10% moisture level and then it was converted to kg ha-1. solomon et al. east african journal of sciences volume 13 (2) 145-158 148 harvest index (hi): proportion of dry grain yield to the aboveground biological yield (biomass yield) was calculated as follows: hi= biomass production rate (kg ha-1 day-1) = seed growth rate (kg/ha/day) = grain yield per day (kg/ha/day) = bean anthracnose severity: bean anthracnose severity (1-9 scales) was pre-transformed into percentage values and then percentage values were arcsine transformed for statistical data analysis (little and hills, 1978). 2.4.2. collected data on plant basis plant height (cm): the plant heights of five randomly taken plants from each of the two middle rows were measured from the ground level to the tip of the plant at physiological maturity and expressed as an average of heights of five plants per plot. number of pods per plant: the number of pods per plant was counted from five randomly taken plants from the middle two rows and expressed as an average for each plot. number of seeds per pod: number of seeds was counted from five random pods from each of five randomly taken plants per plot and expressed as an average of five plants per plot. number of seeds per plant: it was determined by multiplying the number of pods per plant and number of seeds per pod. grain yield per plant (g): the average seed yield in grams obtained from five randomly taken plants in each plot. 3.5. statistical data analysis all the measured variables were subjected to analysis of variance (anova) following gomez and gomez (1984). the general linear model (glm) of sas statistical package version 9.2 software (sas, 2009) was employed for the analysis. the following model was used for computing the analysis of variance. for over location anova = pijk=  + bi+ vj + lk + (vl)jk + e ijk where pijk= phenotypic observation on variety j in block i at location k (i = 1…b, j = 1…v, and k = 1…l) and b, v and l stand for number of blocks, varieties and location, respectively,  = grand mean, bi= the effect of block i with in location k, vj = the effect of variety j, lk = the effect of location k, (vl)jk = the interaction effect between variety and location, and e ijk = error. for individual location anova = yij = μ+ vi + bj + eij where: yij = observed value of variety i in block j, μ= grand mean of the experiment, vi = effect of variety i, bj = effect of block j, ℮ij = error effect of variety i in block j. least significant difference (lsd) was used to separate treatment means when analysis of variance showed significant differences at 5% probability level. least significant difference means for significantly different interaction effects were separated by sas model (p = 0.05). the homogeneity of error mean squares between the two locations was tested by f-test on variance ratio and combined analyses of variance were performed for the traits whose error mean squares were homogenous (when the error mean square of one location less than by three fold the error mean square of the second location) using proc glm procedure of sas. the annual rate of genetic gain achieved from past breeding efforts in grain yield and the associated agronomic traits was calculated by regressing the mean performance of each variety on the year of release (expressed as the number of years since 1973) for that variety. the relative annual gains achieved over the years of releases in different characters were determined as the ratio of annual genetic gain, which was estimated from regression to the corresponding estimated values of the oldest variety and expressed as percentage. annual rate of gain (b) : covxy varx where x = the year of variety release, y = the mean value of each character for each variety, cov = covariance and var = variance. correlation coefficients among all characters were calculated using means of each character as: correlation coefficient between x and y (rxy) : where rxy = correlation coefficient between x and y, cov(x, y) = covariance between x and y, var (x) = variance of x and var (y) = variance of y. stepwise regression analysis was carried out on the varietal mean using proc stepwise in minitab to determine those traits that contributed much to yield variation among varieties by using grain yield (response) as dependent variable and the other characters (predictors) as independent variable. solomon et al genetic progress and reaction to anthracnose of bean 149 3. results and discussions 3.1. analysis of variance the combined analysis of variance of large-seeded food type of common bean varieties showed that variety by location interaction had significant (p≤0.01) differences for seed growth rate, yield (gram plant-1), grain filling period and days to 50% flowering and significant (p≤0.05) for grain yield per day, number of seeds per plant, number of seeds per pod and number of pods per plant (table 3). 3.2. performance of the varieties the combined mean performance of hundred seed weight ranged from the lowest 25.63 g for ayenew to the highest 51.65 g for fedis variety, the grand mean being 40.7 g (table 4). this clearly indicated that common bean varieties released as large-seeded food type in ethiopia so far had significant variation for seed weight trait to be exploited in the future breeding programs. 3.3. genetic progresses from breeding 3.3.1 grain yield there was an average reduction by 720.9 kg ha-1 (5.94%) in grain yield for large-seeded food type of common bean varieties for the past 15 years (table 5) or an annual rate of genetic reduction by 48.06 kg ha-1 (0.39% ha-1 year-1), computed using the first released variety, gofta, as a reference (table 5 and figure 1). this is in contrast with the finding of kebere et al. (2006) who reported that the average relative annual gain in grain yield of haricot bean varieties since 1972 was 3.24% year-1, or about 84.24% for the whole period of 26 years and barley (1.34% ha-1 year-1), (fekadu et al., 2011) solomon et al. east african journal of sciences volume 13 (2) 145-158 150 table 3. mean squares from the combined analysis of variance of 14 large-seeded food type of common bean varieties evaluated over two locations in west shoa during 2014 main cropping season. characters source of variations mean cv (%) r2 location (1) replication (2) variety (13) vxl (13) error (26) days to flowering (df) ** ns ** ** 0.96 36.3 2.7 0.94 days to maturity (dm) ** ns ** ns 4.59 83 2.6 0.79 plant height (ph) ** ns ** * 102.59 57.3 17.66 0.84 number of pods per plant (nppp) ** ns ** * 4.9 10.7 20.6 0.69 number of seeds per pod (nspp) ** ns ** ns 0.27 4.2 12.6 0.58 number of seeds per plant (nsppt) ** ns ** * 133.92 44.3 26.1 0.63 pod length (pl) ** ns ** ns 0.55 10.6 7.0 0.84 grain filling period (gfp) ns ns ** ** 6.62 47.7 5.4 0.6 yield in gram per plant (ygpt) ** * ** ** 25.24 18.4 27.3 0.69 hundred seed weight (hsw) ** * ** ns 17.54 40.7 10.3 0.85 biomass production rate in kg ha-1 day-1 (bmpr) ** * ** ns 242.3 68.2 22.8 0.78 seed growth rate in kg ha-1 day-1 (sgr) ** ** ** ** 65.8 37.9 21.4 0.84 grain yield per day in kg ha-1 (gyd) ** ** ** * 21.84 22 21.3 0.85 solomon et al genetic progress and reaction to anthracnose of bean 151 table 4. mean performance of the varieties from combined analysis for hundred seed weight of largeseeded food type common bean varieties at bako and gute, west shoa, in 2014/2015 main cropping season. s.no. large-seeded food type common bean varieties 100 seed weight (g) 1. gofta 29.36 2. ayenew 25.63 3. melke 42.76 4. ibado 44.63 5. red kidney 47.78 6. kufanzic 30.26 7. loko 46.05 8. glp-2 45.91 9. morka 43.63 10. hirna 45.03 11. hundane 42.13 12. babile 37.01 13. tinike 38.01 14. fedis 51.65 mean 40.7 lsd (5%) 4.8 several similar reports indicated high increases in grain yields of some crops in other countries, like northeast china where high annual yield increase of 0.58% ha-1 per year was obtained from breeding soybean (jin, et al., 2010); canada where 0.45% ha-1 per year increase was obtained from breeding soybean (morrison, et al., 2000); and england where 0.39% ha-1 per year increase was realized from barley breeding for over hundred years (riggs, et al., 1981). on the other hand, the finding of the present study is in agreement with the investigation by egli (2008) who stated that very low grain yield, which was explained in the "attainment of yield plateaus", was also obtained from soya bean breeding in western usa. previously, it was reported that cultivar seed size and yield potential of common bean were negatively associated (peter. et. al., 1994). here in the current study, among large-seeded food type common bean varieties, gofta and ayenew were released in the same year, 1997; but, the variety gofta was chosen as a reference variety to compare and contrast with the other tested common bean varieties since it has an advantage over the variety ayenew for its high yielding potential when it was released and has been extensively distributed to the farmers by its hosting institution, haramaya university. figure 1. bi-plot of grain yield of large-seeded food types of common bean varieties against years of varietal release table 5. annual relative genetic gain (anrgg) and average relative genetic gain (argg) in % compared to the oldest variety gofta of large-seeded food type common bean variety. trends in genetic progress obtained from breeding common bean for biomass yield, grain yield, seed size, harvest index and anthracnose severity during the past 15 years. characters characters mean square of regressio n regressi on coefficie nt (b) p value coefficient of determinatio n (r2) gain in 15 years kg ha1 anrg g year1 (%) argg (%) biomass yield (kg ha-1) 75081.9 12.7 0.86 0.004 190.5 0.13 2.04 grain yield (kg ha-1) 1059099 -48 0.02 0.38 -720.9 -0.39 -5.94 seed weight (g) 215.52 0.68 0.05 0.28 10.2 0.34 5.16 harvest index (%) 0.008 -0.004 0.021 0.37 -0.06 -1.11 -16.61 bean anthracnose severity (%) 71.5 0.39 0.26 0.107 -5.85 -0.07 -1.10 non-consistent gradual reduction of yield of this largeseeded food type of common bean varieties across recently released varieties (table 6) implies that common bean breeding in our country needs future solomon et al. east african journal of sciences volume 13 (2) 145-158 152 attention for better responses through different breeding strategies, like crossing. for example, if we compare the mean grain yield (2627.1 kg ha-1) (table 6) of gofta, which is one of oldest released common bean varieties, and the mean grain yield (1050.2 kg ha-1) of glp-2, the recently released variety, the mean grain yield of the latter was less by 1576.9 kg ha-1 (59.1%) than the grain yield of gofta. on the other hand, the mean grain yield (1455.4) kg ha-1) of hirna variety, the most recently released variety, was less by 1171.7 kg ha1 (44.6%) than the mean grain yield (2627.1 kg ha-1) of gofta variety (table 6). only the variety ayenew, which was released in the same year 1997, exceeded by 52.4 kg ha-1 (2%) the mean grain yield (2679.5 kg ha-1) of the variety gofta. the possible main reasons for the lower genetic progresses made for these large-seeded food type common bean varieties were the stability and better adaptation of the first released variety, gofta (table 6). therefore, to bring the drastic change for large-seeded common bean varieties through breeding, the ethiopian researchers are advised to apply rigorous breeding strategies like earlier study when gofta and ayenew varieties were first released and to come up with other promising varieties both in yield and disease resistant. 3.4 associations of characters the correlation coefficient is the measures of degree of symmetrical association between two traits and it is used for understanding the nature and magnitude of association among yield and yield components. association between any two traits or among various traits is of very importance to make desired selection of combination of traits (ahmad et al., 2003). therefore, the correlated characters for each other of large-seeded food type of common bean varieties are tabulated hereunder (tables 7). solomon et al genetic progress and reaction to anthracnose of bean 153 table 6. mean performance and their percentage increase in biomass yield (kg ha-1), grain yield (kg ha-1), seed weight (g), harvest index (%),and bean anthracnose severity (%) of large-seeded food type common bean varieties released during the past 15 years compared to the first released variety gofta. varieties y e ar o f re le as e characters grain yield seed weight harvest index biomass yield anthracnose severity m e an w e ig h t (k g h a1 ) increase over gofta variety mea weight (g) increase over gofta variety mean index (%) increase over gofta variety (%) mean yield (kg ha-1) increase over gofta variety mean severity (%) reduction from gofta variety (%) (kg ha-1) (g 100-1 seeds, %) (kg ha-1) gofta 1997 2627.1 29.36 0.39 5416.7 10.14 ayenew 1997 2679.5 52.4 2 25.63 -3.73 -12.7 0.34 -12.8 6041.7 625 11.5 18.54 -82.8 melke 1998 1928.7 -698.4 -26.6 42.76 13.4 45.6 0.27 -30.8 6302.1 885.4 16.3 13.48 -32.9 ibado 2003 1464.8 -1162.3 -44.3 44.63 15.27 52 0.27 -30.8 5364.6 -52.1 -1 11.85 -16.8 red kidney 2007 1473.2 -1153.9 -44 47.78 18.42 62.7 0.30 -23.1 4166.7 -1250 -23.1 11.85 -16.8 kufanzic 2008 2079.8 -547.3 -20.8 30.26 0.9 3 0.30 -23.1 5052.1 -364.6 -6.8 23.7 -133.7 loko 2009 1630.4 -996.7 -38 46.05 16.69 56.8 0.28 -28.3 5156.3 -260.4 -4.8 10.14 glp-2 2011 1050.2 -1576.9 -59.1 45.91 16.55 56.4 0.29 -25.7 3385.4 -2031.3 -37.5 20.28 -100 morka 2011 1633.8 -993.3 -37.8 43.63 14.27 48.6 0.30 -23.1 5468.8 52.1 1 11.85 -16.8 hirna 2012 1455.4 -1171.7 -44.6 45.03 15.67 53.4 0.23 -41.1 7864.6 2447.9 45.2 36.9 -263 hundane 2012 1825.9 -801.2 30.5 42.13 12.77 43.5 0.28 -28.3 6406.3 989.6 18.3 20.3 -100.2 babile 2012 1707.4 -919.7 -35 37.01 7.65 26 0.30 -23.1 4947.9 -468.8 -8.7 13.57 -33.8 tinike 2012 1549.2 -1077.9 -41.1 38.01 8.65 29.5 0.24 -29.5 6250 833.3 15.4 15.2 -49.9 fedis 2012 2180.6 -446.5 -17 51.65 22.29 75.9 0.27 -30.8 7500 2083.3 38.5 16.9 -66.7 solomon et al. east african journal of sciences volume 13 (2) 145-158 154 table 7. correlation coefficients (r-values) of yield and yield related traits of large-seeded food type common bean varieties. characters df dm ph nppp nspp nsppt pl gfp ygpt sw hi bmpr bmy sgr gyd gy ansiv df 0.59 0.17 -0.19 0.05 -0.17 0.07 -0.35** -0.15 -0.10 -0.34** -0.26* -0.19 -0.32** -0.41** -0.36** -0.19 dm 0.01 -0.01 -0.01 -0.03 0.01 0.54** 0.13 0.20 -0.50** 0.08 0.19 -0.32** -0.33** -0.23* 0.08 ph 0.45** 0.01 0.44** 0.12 -0.16 0.17 -0.33** 0.29** 0.34** 0.32** 0.48** 0.45** 0.45** 0.18 nppp 0.15 0.91** 0.24* 0.14 0.75** 0.04 0.28** 0.29** 0.27* 0.42** 0.43** 0.44** 0.04 nspp 0.42** -0.17 -0.07 0.22* -0.24* 0.29** -0.33** -0.33** -0.04 -0.05 0.06 -0.16 nsppt 0.12 0.14 0.78** -0.04 0.34** 0.16 0.15 0.36** 0.37** 0.38** 0.01 pl -0.07 0.29** 0.48** -0.17 0.25** 0.24* 0.07 0.06 0.06 0.07 gfp 0.30** 0.34** -0.22* 0.37** 0.43** -0.02 0.05 0.12 0.29** ygpt 0.39** 0.03 0.22* 0.23* 0.18 0.20 0.23* 0.03 sw -0.49** 0.31** 0.33** -0.17 -0.14 -0.10 0.02 hi -0.11 -0.18 0.66** 0.65** 0.60** -0.25* bmpr 0.99** 0.62** 0.65** 0.68** 0.39** bmy 0.56** 0.59** 0.64** 0.40** sgr 0.99** 0.98** 0.00 gyd 0.99** 0.03 gy 0.04 ansev note: ** and *, highly significant at p < 0.01 and significant at p < 0.05 respectively; and values with no asterisks are insignificant; df = days to 50% flowering, dm = days to maturity, ph = plant height (cm), nppp = number of pods plant-1, nspp = number of seeds pod-1, nsppt = number of seeds plant-1, pl = pod length (cm), gfp = grain filling period, ygpt = yield gram plant-1, sw = seed weight (g), hi = harvest index (%), bmpr = biomass production rate( kg ha-1), bmy = biomass yield (kg ha-1), sgr = seed growth rate (kg ha-1), gyd = grain yield (day-1 kg ha-1), gy = grain yield (kg ha-1), ansev = anthracnose severity (%) solomon et al genetic progress and reaction to anthracnose of bean 155 the association of characters of large-seeded food type common bean varieties ranged from -0.50 to 0.99 (table 7). grain yield was negatively associated with days to flowering (r = -0.36**) and days to physiological maturity (r = -0.23), while it was positively correlated with plant height (r = 0.45**), number of pods per plant (r = 0.44**), biomass yield (r = 0.64**), biomass production rate in kilogram per day (r = 0.68**), number of seeds plant-1 (r = 0.38**), seed growth rate in kilogram per day (r = 0.98**), grain yield in kilogram per day per hectare (r = 0.99**), harvest index (r = 0.60**) (table 7). similarly, correlation between grain yield with grain yield per day (white and izquierdo, 1991), with grain yield per day and biomass production rate were highly correlated (teklu, 1998). some authors also stated that grain yield was related positively with biomass yield; for instance, kebere et al. (2006) on haricot bean; laing et al. (1984) and saladonavaro et al. (1993) on soybean; and teklu (1998) on tef, obtained similar results. but, the findings of these authors indicated that grain yield showed no association with harvest index on their respective studied crops; this contradicts with the present finding. on the other hand, other authors reported that grain yield had positive association with both biomass yield and harvest index (riggs et al., 1981; waddington et al., 1987; perry and d’antuono, 1989) and their findings are in agreement with the current study. in another case study, tarekegne (1994) stated that no relation between grain yield and biomass yield and positive association between grain yield and harvest index were reported on bread wheat. according to kebere et al. (2006), seed growth rate, grain yield per day and biomass production rate were positively associated with grain yield. as kebere et al. (2006) stated, there was no correlation between grain yield and plant height; but the present finding stated that there was strong association between grain yield and plant height and supported with the finding of riggs et al. (1981) who reported positive association in wheat and negative association in spring barley, respectively, between grain yield and harvest index. grain yield was positively correlated with grain yield per plant (r = 0.23*) and negatively correlated with days to physiological maturity (r = -0.23*) (table 7). the current finding revealed that grain yield had no association with number of seeds per pod (r = 0.06), pod length (r = 0.06), grain filling period (r = 0.12) and hundred seed weight (r = -0.10). similar results were reported by kebere et al. (2006) who stated that there was no association among grain yields and number of seeds per pod, pod length and hundred seed weight. several authors also observed no association between grain yield and hundred seed weight (riggs et al., 1981; waddington et al., 1987; white and izquierdo, 1991; tarekegne, 1994; teklu, 1998). in contrast, positive correlations were recorded for grain yield with the number of seeds per pod and mean seed weight in soybean (karmakar and bhatnagar, 1996), with the number of grains per ear in wheat (perry and d’antuono, 1989). according to this finding, plant height (r = 0.45**), number of pods per plant (r = 0.44**), number of seeds per plant (r = 0.38**), harvest index (r = 0.60**), biomass production rate in kilogram per hectare per day (r = 0.68**), biomass yield in kg per hectare (r = 0.64**), seed growth rate in kilogram per hectare per day (r = 0.98**) and grain yield per day in kilogram per hectare (r = 0.99**) were highly correlated with grain yield (kg ha-1); so, plant breeders can possibly increase the final output by improving these characters, particularly the most interesting character, grain yield. according to this study, bean anthracnose severity had no association with grain yield for large-seeded food type common bean varieties. but, characters like grain filling period (r = 0.29**), biomass production rate in kilogram per hectare per day (r = 0.39**), biomass yield in kilogram per hectare (r = 0.40**) was highly correlated; while harvest index (r = -0.25*) negatively correlated with anthracnose severity; for the rest studied characters, anthracnose severity had no association (table 7). number of pods per plant and number of seeds plant (r = 0.91**), biomass yield in kilogram per hectare and biomass production rate in kilogram per hectare per day (r = 0.99**), seed growth rate in kilogram per hectare per day and grain yield in kilogram per day per hectare (r = 0.99**), grain yield in kilogram per day per hectare and grain yield in kilogram per hectare (r = 0.99**) and seed growth rate in kilogram per day per hectare and grain yield in kilogram per hectare (r = 0.98**) was strongly associated with each other in these large-seeded food type of common bean varieties during the study season. grain yield as a dependent variable, other unmentioned characters as independent variables and the stepwise regression analysis of the large-seeded food type of common bean varieties are tabulated hereunder (table 8). grain yield per day and days to physiological maturity were the most important characters that greatly contributed to the variation of grain yield of these common bean varieties (table 8). grain yield per day contributed 82.5%, while days to maturity contributed 21.8% of the total variations in grain yield. on the contrary, seed size and anthracnose severity contributed 40.2 and 9.3%, respectively, for the reduction of grain yield. solomon et al. east african journal of sciences volume 13 (2) 145-158 156 table 8. summary of selection from stepwise regression analysis of mean grain yield of large-seeded food type common bean varieties as dependent variable on the other traits as independent variables. note: ** = significant difference at p < 0.01, r2 = coefficient of determination and vif = variance inflation factor 4. conclusion the averages over locations grain yield ranged from 1050.2 kg ha-1 for glp-2 variety to 2679.5 kg ha-1 for ayenew. the tested common bean varieties were found to be genetically different. the tested common bean varieties exhibited significant differences for most of the studied characters, and locations also exerted considerable effects on common bean varieties. however, the common bean variety by location interactions on anthracnose severity (%) from largeseeded food made crossover type of interaction as well or the different varieties performed in different way at different locations. the older released varieties were more stable and better adapted than the recent ones; grain yields of large-seeded food type common bean varieties were reduced by 48.06 kg ha-1 (0.39%) annually and 720.9 kg ha-1 (5.85%) in the period of genetic improvement for the past fifteen years. this is because most of the recent large-seeded food type common bean varieties are released for their type to export than yield production. relatively, better genetic progress was obtained from breeding large-seeded food type of common bean varieties in ethiopia in seed size and biomass yield than in grain yield, harvest index and anthracnose resistance for the last 15 years of breeding period. therefore, to bring drastic changes for these characters, appropriate breeding strategies should be devised for future research consideration to come up with effective yield gains like crossing. when we consider the past improvement, genetic progress made for large-seeded food type of common bean varieties decreased due to the consistent performance of the first released variety, gofta and the increase in seed size and anthracnose development as stepwise regression reflected. therefore, from stepwise regression point of view, grain yield per day would be praised by plant breeders to generate attractive yield; days to maturity also would be considered as well. the homework for the next investigator should be further identification of the important character(s) that contribute more to the variation of grain yield of common bean varieties and including well practicing of crossing for this crop. big seed size and anthracnose severity were considered as a reason for the reduction of the yield. therefore, even if big seed size of common bean has a contribution on the market, it has the problem on the reduction of the yield and disease development; especially, anthracnose disease will be considered for the next researcher. finally, among these evaluated large seeded food type common bean varieties, ayenew (26.79.5 kg ha-1) , gofta (2627.1 kg ha-1) and fedis (2180.6 kg ha-1) will be recommended for the area. 5. acknowledgements this piece of research work was part of a postgraduate research work at haramaya university. dr. firew mekbib, dr. gemechu keneni and dr. berhanu amsalu are acknowledged for their comments and suggestion given on the research work. oromia agricultural research institute (oari) and bako agricultural research center (barc) are acknowledged for their financial support. melkasa agricultural research center (marc), haramya university (hu) and sirinka agricultural research center (sarc), are also praised for providing common bean varieties. finally, we wish to express our heartfelt gratitude to all individuals, who were involved directly or indirectly in the research activity, for their friendly assistance and affection and support given during the research work. 6. references ahmad, m., mohammad, f., maqbool, k., azam, a. and iqbal, s. 2003. genetic variability and trait correlation in wheat. sarhad journal of agriculture, 19 (3): 347-351. broughton, 2003. ‘bean (phaseolus spp.) – model food legumes.’ plant & soil, 252. donmez, e., sears, r.g., shroyer, j.p. and paulsen, g.m. 2001. genetic gain in yield attributes of winter wheat in the great plains. crop science, 41:14121419. grain yield independent variable interception regression coefficients (b) r2 vif grain yield day-1 -1834 -0.643** 0.825 5.03 days to maturity 0.177** 0.218 5.03 seed weight 0.685** -0.402 4.07 anthracnose severity 0.395** -0.093 1.04 solomon et al genetic progress and reaction to anthracnose of bean 157 csa (central statistics agency of ethiopia) (2016) report on area and crop production of major crops for 2016 meher season, 1: 125. egli, d.b. 2008. soybean yield trends from 1972-2003 in mid-western usa. field crops research. 106: 53-59. evans, l.t. and fischer, r. a. 1999. yield potential: its definition, measurement, and significance. crop science, 39: 1544-1551. fekadu, w., zeleke, h. and ayana, a. 2011 genetic improvement in grain yield potential and associated traits of food barley (hordeum vulgare l.) in ethiopia. ethiopian journal of applied science and technology. 2 (2): 43-60. ferris, s. and kaganzi, e. 2008. evaluating marketing opportunities for haricot beans in ethiopia. paper 7. in: ipms (improving productivity and market success) of ethiopian farmers project working ilri (international livestock research institute), nairobi, kenya. 68 gomez, k. and gomez, a. 1984. statistical procedurefor agricultural research. 2nd ed. international rice research institute. john wiley and sons inc.680 pp. jin, j,. liu, x., wang, g., mi, l., shen, zh, chen. x. and herbert, s.j. 2010 agronomic and physiological contributions to the yield improvement of soybean cultivars released from 1950 to 2006 in northeast china. field crops research. 115: 116-123. karmakar, g. and bhatnagar, s. 1996. genetic improvement of soybean genotypes released in india from 1969 to 1993. euphytica, 90: 95-103. kebere bezaweletaw, ketema belete and prapa sripichitt, 2006. genetic gain in grain yield potential and associated agronomic traits in haricot bean (phaseolu vulgaris l.). kasetsart journal (natural science), 40: 835-847. laing, d. r., jones, p. g. and davis, j.h.c. 1984. common bean (phaseolus vulgaris l.). pp. 305-351. in: goldsworthy p.r. and fisher n.m. (eds.). the physiology of tropical field crops, john wiley, new york, usa. 23: 91-105. little, t. m. and hills, f. j. 1978. agricultural experimentation: design and analysis. john wiley and sons, new york. 38:273-452. meteorological data of bako agricultural research center (2014) moa (ministry of agriculture). 2014. ministry of agriculture, animal and plant health regulatory directorate. crop variety register issue no. 17, june 2014, addis ababa, ethiopia. morrison, m. j., voldeng, h. d. and cober, e. r. 2000 agronomic changes from 58 years of genetic improvement of short-season soybean cultivars in canada. agronomy journal. 92: 780-784. perry, m.w. and antuono, m.f.d'. 1989. yield improvement and associated characteristics of some spring wheat cultivars introduced between 1960 and 1982. journal of australian agricultural research, 50: 457-472. peter, j., sexton, j., white. j. w., kenneth, w. and boote j., 1994. yield determining processes in relation to cultivar seed size of common bean. field crops res. 34:8-91. riggs, t. j., hanson, p.r., start, n. d., miles, d. m., morgn, c. l. and dord, m. a. 1981 comparison of spring barley varieties grown in england and wales between 1880 and 1980. journal agricultural science. 97: 599-610. sas (statistical analysis system). 2009. salado-navarro, l.r., sinclair, t.r. and hinson, k. 1993. changes in seed yield and seed growth traits in soybean cultivars released in southern usa from 1945 to 1983. crop science, 33: 1204-1209. tarekegne, a. 1994. yield potential of rainfed wheat in the central highlands of ethiopia. msc thesis. alemaya university of agriculture, alemaya, ethiopia. 3: 41-59 teklu, y. 1998. genetic gain in grain yield potential and associated agronomic traits of tef (eragrostis tef (zuss) trotter). msc thesis. alemaya university of agriculture. alemaya, ethiopia. tesfaye b (1997) loss assessment study on haricot bean due to anthracnose. pest management journal of ethiopia 1: 69-72. waddington, s., ransom, s. osamanzi, m. and sounders, d. 1986. improvement in the yield potential of bread wheat adapted to northwest mexico. crop science, 26: 699-703. white, j. w. and izquierdo, j. 1991. physiology of yield potential and stress tolerance, pp. 287-382. in: van schoonhoven a. and voysest o. (eds.). common bean: research for crop improvement. c.a.b. international. nillingford, uk. wortmann, c. s., kirkby, r. a., eledu, c. a. and allen, d. j. 1998. atlas of common bean production in africa, ciat, cali, colombia. 133 pp solomon et al. east african journal of sciences volume 13 (2) 145-158 158 east african journal of sciences (2019) volume 13 (2) 185-194 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: mitikuguya@yahoo.com attribution-noncommercial 4.0 international license. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) chemical composition, mineral profile and sensory properties of traditional cheese varieties in selected areas of eastern gojjam, ethiopia mitiku eshetu1* and aleme asresie2 1school of animal and range sciences, haramaya university, p.o. box 138, dire dawa, ethiopia 2department of animal production and technology, adigrat university, adigrat, ethiopia abstract: this study was conducted to evaluate the chemical composition, mineral profile and sensory properties of metata, ayib and hazo traditional cheese varieties in selected areas of eastern gojjam. the chemical composition and mineral content of the cheese varieties were analyzed following standard procedures. sensory analysis was also conducted by consumer panelists to assess taste, aroma, color, texture and overall acceptability of these traditional cheese varieties. metata cheese samples had significantly (p<0.05) lower moisture content and higher titratable acidity than ayib and hazo cheese samples. the protein, ash, fat contents of metata cheese samples were significantly (p<0.05) higher than ayib and hazo cheese samples. moreover, phosphorus, calcium, magnesium, sodium and potassium contents of metata cheese samples were significantly (p<0.05) higher than that of ayib and hazo cheese samples. metata cheese samples had also the highest consumer acceptability scores compared to ayib and hazo cheese samples. in general, the results of this work showed that metata cheese has higher nutritional value and overall sensory acceptability. this could be due to the fermentation of the product for several months and use of different types of spices. keywords: chemical composition; consumer acceptability; mineral profile 1. introduction the major fermented milk products in ethiopia produced by smallholder farmers using traditional methods include ergo (fermented sour milk), ititu (fermented milk curd), kibe (traditional butter), neter kibe (clarified butter), ayib (cottage cheese), arerra (defatted sour milk), aguat (whey) (gonfa et al., 2001) and metata (fermented cottage cheese variety) (eyassu, 2013). traditional cottage cheese (ayib) is made from defatted sour milk obtained from churning of sour whole milk and then by heating the product on a slow flame until distinct curd forms. the shelf life of ayib is limited to few days and therefore, it is either consumed at home or marketed as quickly as possible (assefa et al., 2008). there are also some more traditional dairy products known in the mixed and pastoral production systems of the country. metata, hazo and zureshekefign are the traditional fermented cottage cheese varieties produced in northwestern highlands of ethiopia (eyassu, 2013; and geremew et al., 2015). awabal, gozamin, machakel and dejen districts of east gojjam zone are important milk producing areas in amhara national regional state of northwestern highlands of ethiopia. in these areas milk is produced from cows under traditional conditions and processed into different traditional cheese varieties such as ayib, metata, hazo and zureshekefign. these dairy products differ from the traditional cottage cheese. metata cottage fermented cheese production involves the use of various spices, spontaneous fermentation for about 25 days coupled with continuous removal of whey. these products are more shelf stable compared to the most common ayib (which can be kept only for a few days) and properly made metata ayib could be kept for more than 10 years if tightly sealed and stored in a cool place. metata valued by the community for its medicinal and cultural values (tegegne et al., 2013). these products could be of significant nutritional importance for the community with substantial contribution to the country’s economic development. however, there is no adequate information available on their chemical composition, mineral profile as well as sensory properties. nevertheless, it is essential to understand such properties of these traditional dairy products in order to improve manufacturing procedures, standardize the processing parameters, and to provide basic information necessary to improve the quality of these dairy for households use and commercial purpose. the aim of this study was therefore, to evaluate the chemical composition, mineral profile and sensory properties of metata, ayib and hazo traditional cheese varieties along the cheese value chain in selected areas of eastern gojjam, northwestern highlands of ethiopia. 2. materials and methods 2.1. description of the study areas east gojjam is one of the zones in the amhara national regional state of ethiopia. it borders the oromia national regional state in the south, west gojjam zone in the west, south gondar in the north, and south wollo in the east. the bend of the abay mitiku and aleme east african journal of sciences volume 13 (2) 185-194 186 river defines the zone's northern, eastern and southern boundaries. the zone has seventeen districts of which four districts namely, gozamin, awabal, dejen and machakel districts were purposively selected based on dairy potential, history of dairy development interventions and number of crossbred dairy cattle. 2.2. cheese sampling procedures and layout a total of 216 samples (of ≈ 300g each) of the three traditional cheese varieties namely metata, ayib and hazo were collected from dairy producers (120), dairy products retail shops and kiosks (60), and dairy cooperatives (36) from the four selected districts (table 1; figure 1). the samples were placed in sterile bottles (300 g) aseptically and stored in an icebox having ice packs, and delivered to the ethiopian food, medicines and health care administration and control authority (efmhaca) and bless agrifood laboratory services for analysis. total number of samples collected for each cheese variety was 72 (table 1). each sample was analyzed in duplicate for chemical composition, mineral profile and consumer acceptability tests. fig 1. ayib (a), metata cheese variety (b) and hazo cheese variety (c) table 1. cheese sampling procedures and layout districts sampling sources and cheese varieties producers cooperatives dairy prsk metata ayib hazo metata ayib hazo metata ayib hazo total awabal 10 10 10 3 3 3 5 5 5 54 gozamin 10 10 10 3 3 3 5 5 5 54 machakel 10 10 10 3 3 3 5 5 5 54 dejen 10 10 10 3 3 3 5 5 5 54 total 40 40 40 12 12 12 20 20 20 216 note: dairy prsk=dairy product retail shops and kiosks. 2.3. determination of chemical composition 2.3.1. fat content the soxhlet fat extraction method was used to determine the fat content of traditional cheese (metata, ayib and hazo) varieties as described by aoac (1995) method 933.05. three grams for each of the traditional cheese varieties was fed into a soxhlet apparatus fitted with a 1-l round-bottom flask and condenser. the extraction was carried out for 8 hours using n-hexane (boiling point of 68-70°c). the solvent was removed by heating at 70°c in a hot dry oven (pn9410.gl. britain). the recovered oil was then weighed and expressed as fat percentage. where: wa = thimble weight; wb = sample weight before extraction; and wc = sample weight after extraction 2.3.2. moisture content the moisture content of the traditional cheese (metata, ayib and hazo) varieties was determined by drying three grams cheese samples in a forced draft oven (edsc, 99h207: england) at 102±2°c for 3 hours. the moisture content of these traditional cheese samples was calculated according to bradley et al. (1993). 2.3.3. ash content the ash content of cheese samples was determined according to the method described in aoac (1995) method no. 935.42 by igniting the pre-dried cheese samples (≈ 2.0 g) that were used for moisture determination in a muffle furnace (lindberg/blue m mitiku and aleme properties of traditional cheese varieties in eastern gojjam 187 crucible furnace, top loading 100-1200 serious, fisher scientific) at 550℃. then, it was placed in desiccators while cooling and reweighed. the initial and final weights of the cheese samples were taken. the obtained ash weight was divided by original sample weight and expressed in percent. the ash content was calculated according to the following formula. 2.3.4. protein content the total nitrogen content of the traditional cheesevarieties (1 g) was determined by the kjeldahl method as described by the international dairy federation (idf, 1993). the crude protein content of these traditional cheese samples was determined by multiplying the nitrogen content by the factor 6.38. where: % n= percentage nitrogen by weight, vs = volume of hcl used for titration of sample vb = volume of hcl used for titration of the blank %cp = percentage of crude protein %cp= %n *f; f = 6.38 was used as conversion factor 2.3.5. ph determination the ph of the traditional cheese varieties was measured using a digital ph meter (crison, barcelona, spain). 2.3.6. titratable acidity the titratable acidity of the traditional cheese varieties was determined by measuring 10 g of finely grounded traditional cheese samples and adding water (40℃) to a volume of 105 ml. after vigorous shaking, the mixture was filtered and an aliquot of the filtrate (25 ml) was titrated with 0.1 n sodium hydroxide solution using phenolphthalein as indicator. the titratable acidity was expressed as % lactic acid and calculated according to the procedure of aoac (1995) method 920.124. 2.4. determination of mineral profile the mineral profile (phosphorus, calcium, magnesium, sodium and potassium) of the traditional cheese varieties were determined according to the procedure of aoac (1995) method 999.10 using atomic absorption spectrophotometer (model phillip pu9100x) with a hollow cathode lamp and a fuel rich flame (air-acetylene). ten gram of each cheese sample were incinerated to a white ash at 550℃ in a muffle furnace for 4 hours, cooled and the ash was washed into 250 ml beaker with 30 ml of concentrated trioxonitrate acid evaporated to dryness on steam bath, the residue was further heated for 30 minutes, there after the sample was dissolved in 40 ml of hydrochloric acid (hcl) at a ratio of 1:1 and digested for about 2 hours on a hot plate magnetic stirrer. 1 ml of dilute hydrochloric acid was further added to the sample and boiled for about 1 hour, filtered with whatman number four filter paper, washed with hcl and the volume made up to 100 ml with distilled water. samples were aspirated and the mean signal responses were recorded at each of the element respective wavelength. 2.5. sensory analysis sensory evaluation of the traditional cheese (metata, ayib and hazo) varieties was conducted by consumer panelists according to the method described by resurrecin (1998). a total of fifty-eight adult consumers took part in the sensory analysis and they were requested to evaluate the sensory attributes of the cheese samples and fill the prepared questionnaire. consumer panelists were selected based on the following criteria: age between 18-40 years old and they have to be “consumers” of fermented milk products. metata, ayib and hazo traditional cheese samples (20 g) were placed in three-digit coded white plastic plates and served in a bright well-ventilated room. bottled water was provided to the panelists to rinse their mouth after each taste. the taste, color, aroma, texture, appearance and overall acceptability of metata, ayib and hazo traditional cheese samples were evaluated using a 5point hedonic scale (5 = like very much, 4 = like moderately, 3 = neither like nor dislike, 2 = dislike moderately and 1 = dislike very much). these traditional cheese samples were presented in a random fashion. the sensory evaluation was conducted at the ethiopian food, medicines and health care administration and control authority (efmhaca). 2.6. data analysis data related to chemical composition, mineral profile and sensory properties of the traditional cheese varieties (metata, ayib and hazo) were analyzed using the general linear model procedure of the sas (version 9.1, 2008). means were separated by duncan multiple range test. significant differences were declared at 5% significance level. the model used; yijk = µ + αi + єijk where: yijk = chemical composition, mineral profile and sensory properties of cheese varieties µ = overall mean; αi = cheese varieties; and єijk = random error. mitiku and aleme east african journal of sciences volume 13 (2) 185-194 188 3. results and discussion 3.1. chemical composition of traditional cheese varieties the moisture content of metata cheese samples was significantly (p<0.05) lower than that of ayib and hazo cheese varieties regardless of their sources (table 2). the lower moisture content of metata cheese as compared to ayib and hazo cheese varieties might be due to continuous loss of water from the curd as a result of lactic acid development which causes curd contraction and syneresis during the production process and ripening period (terzic-vidojevic et al., 2007). the moisture content of metata cheese observed in the current study is in agreement the finding of eyassu (2013) who reported 42.3% moisture content for metata cheese variety, and with the moisture content of halloumi cheese made from goat milk, cow milk and their mixture which was found to be 41.33% (elgaml et al., 2017). table 2. the chemical composition of the traditional cheese varieties (mean ± se) (n=216). cheese varieties variables sampling sources metata ayib hazo moisture (g/100 g) dp 38.53±0.69b 78.33±0.69a 77.15±0.55a dc 38.59±1.22b 78.71±1.26a 76.35±1.26a dr 41.27±0.95b 78.49±0.98a 78.18±0.98a fat (g/100 g) dp 31.89±0.41a 1.42±0.47b 1.43±0.34b dc 30.86±0.91a 1.40±0.86b 1.42±0.62b dr 30.19±0.70a 1.44±0.67b 1.41±0.48b ash (g/100 g) dp 4.55±0.93a 1.17±0.11b 1.16±0.31b dc 4.57±0.17a 1.16±0.24b 1.15±0.22b dr 4.52±0.13a 1.15±0.14b 1.17±0.12b crude protein (g/100 g) dp 41.54±6.29a 16.78±0.28b 15.03±2.88b dc 40.82±3.21a 14.59±1.61b 14.94±2.61b dr 41.44±1.24a 14.53±1.24b 14.40±6.24b ph dp 4.18±0.05b 4.49±0.04a 4.44±0.06a dc 4.12±0.15b 4.53±0.14a 4.54±0.16a dr 4.26±0.11b 4.48±0.12a 4.47±0.14a ta (% lactic acid) dp 0.73±0.02a 0.44±0.02b 0.45±0.02b dc 0.72±0.03a 0.43±0.03b 0.44±0.03b dr 0.74±0.02a 0.44±0.02b 0.46±0.02b note: dp = dairy producers, dc = dairy cooperatives, dr = dairy product retail shops and kiosks, ta = titratable acidity, n = sample size and a,b means with different superscript letters in a row for each variables under the three sampling sources and cheese varieties are significantly different (p<0.05). the fat, ash and crude protein content of metata cheese samples were significantly (p<0.05) higher than that of ayib and hazo cheese samples collected from different sources (table 2). however, there was no significant (p>0.05) difference in fat, ash and protein content between ayib and hazo cheese samples. the fat content of metata cheese (30.19 31.89 g/100 g) obtained in the present study is slightly higher than the fat content of metata cheese (28.7±8.4 (g/100 g) reported in western gojjam zone of amhara region, ethiopia (eyassu, 2013). however, the fat content of ayib (1.16-1.52 (g/100 g) reported by regu et al. (2016) is much lower than metata ayib obtained from the present study. the higher fat content of metata cheese compared to ayib and hazo cheese varieties means that it could serve as an important source of energy and essential fatty acids in human nutrition. fat has many important functions in food; it contributes to the taste, texture and appearance of the cheese (manson and willet, 2001). the average ash content of metata cheese recorded in the present study is similar to the ash content of cheese made from cow milk (4.53%) and buffalo milk (4.67%) (masud et al., 1992). the higher ash content of metata mitiku and aleme properties of traditional cheese varieties in eastern gojjam 189 cheese compared to ayib and hazo cheese varieties might be due to the effect of spices, the reduction of moisture content and absorption of salt by cheese curd during ripening. metata cheese had more or less similar protein content with the findings of eyassu (2013) who reported protein content of metata ayib to be 43.0±6.9% (g/100 g). the higher protein content of metata cheese samples might be due to an increase in soluble protein contents during storage as a result of continuous proteolysis of protein and a decrease in moisture content during ripening. the higher crude protein content observed in metata cheese samples in the present study could serve as an important source of amino acids in human nutrition and its consumption will help to ameliorate protein deficiencies. cheese contains biologically valuable proteins that are almost 100% digestible, as the ripening phase of the manufacturing process involves a progressive breakdown of caseins to water soluble peptides and free amino acids (lopez-expsito et al., 2012). the ph values of metata cheese samples was significantly (p<0.05) lower than that of ayib and hazo cheese samples collected from different sources (table 2). the ph value observed in the present study is similar with the findings of kassa (2008) who reported a ph value of 4.34 for ethiopian traditional cottage cheese (ayib) samples collected from a local market in shashemene area, southern ethiopia. the lower ph values observed in metata cheese samples might be associated with the fermentation of lactose to lactic acid resulted in reduction of ph and rise in acidity. cheese ph directly influences chemical changes in the protein network of the cheese curd, with high ph leads to increased interactions among proteins (floury et al., 2009). the variation in ph values most probably originated from acidifying activities of lactic acid bacteria (lab) present in cheese (prodromou et al., 2001). in contrary to this, an increase in ph value may occur during cheese ripening which might be as a result of yeast metabolic activity which uses lactic acid as a source of carbon or a result of great amounts of alkaline compounds released during proteolytic activities (volken de souza et al., 2003). the titratable acidity of metata cheese samples was also significantly (p<0.05) higher than that of ayib and hazo cheese samples (table 2). the present result is not in agreement with the finding of eyassu (2013) who reported titratable acidity of 0.43±0.07 for metata cheese samples collected from northwestern gojjam. the higher titratable acidity observed in metata cheese samples in the current study might be associated with the growth of lactic acid bacteria that increased the level of lactic acid and consequently resulted in the low ph values of the cheese. titratable acidity is regulated by the amount of lactose fermented to lactic acid and the buffering capacity of the curd during manufacturing of the cheese (kafili et al., 2009). lactobacilli may utilize the residual lactose in cheese during ripening and contribute to increased titratable acidity of the cheese (arenas et al., 2004). 3.2. mineral profile of metata, ayib and hazo cheese varieties the mineral contents of metata, ayib and hazo varieties collected from different sources are presented in table 3. the mineral content of metata cheese samples was significantly (p<0.05) higher than that of ayib and hazo cheese varieties for all the three sampling sources. however, there was no significant (p>0.05) difference observed in mineral content between ayib and hazo cheese varieties. the value of phosphorus in metata cheese samples observed in the current study is in line with the finding of adetunji and babalo (2011) who reported phosphorus content of 179 (mg/100 g) for wara, a traditional west african soft cheese. phosphorus is the second most abundant mineral in human body with many important biological functions such as acid-base balance, bone and teeth formation, development and maintenance and energy metabolism. (cashman, 2002). although phosphorus is the most important structural component of bones and teeth, excessive intake of phosphorus combined with reduced calcium intake may have negative effects on bones (cashman, 2006). the calcium content of metata cheese samples observed in the current study is in agreement with the finding of gonzalez et al. (2009) who reported 50.26±2.30 (mg/100 g) calcium content in semi-hard cheese during six month of ripening period. the higher calcium content of metata cheese is quite possibly as a result of firmer curd in fermented metata cheese with higher number of calcium phosphate molecules. research showed that insufficient intake of calcium raises the risk of obesity (parikh and yanovski, 2003), hyperlipidemia and insulin-resistance syndrome (teegarden, 2003; zemel, 2004). on the contrary, a diet rich in daily calcium intake enhanced weight reduction in type two diabetic patients (shahar et al., 2007). moreover, calcium is responsible for many regulatory functions, such as normal cardiac rhythm maintenance, blood clotting, hormone secretion, muscle contraction and enzyme activation (cashman, 2002). the magnesium content of metata cheese samples observed in the current study is in agreement with kailas and kapadnis (2015) who reported 49.6 mg/100 g magnesium content of soft cheese samples in nashik region. magnesium plays an important role in many physiological processes, such as metabolism of proteins and nucleic acids, neuromuscular transmission and muscle contraction, bone growth and blood pressure regulation (zamberlin et al., 2012). the sodium content of metata cheese samples observed in the current study is not in agreement with mian et al. (2014) who reported 678 (mg/100 g) sodium content for cheddar cheese made from buffalo milk mitiku and aleme east african journal of sciences volume 13 (2) 185-194 190 and their mixture with cow milk. the higher values of sodium in metata cheese samples might be attributed to multiple additions of sodium chloride during the cheese production. cheese is perceived as containing high levels of sodium, which discourages some consumers from eating cheese (johnson et al., 2009; saint-eve et al., 2009). consumption of too much sodium is associated with high blood pressure and increased risk of heart attack and stroke (smith-spangler et al., 2010; usda, 2010). the potassium content of metata cheese samples observed in the current study is in agreement with slacanac et al. (2011) who reported 202.43±2.44 (mg/100 g) potassium concentration in cheese made from a mixture of croatian goat and cow milk. the higher value of potassium in metata cheese samples could be attributed to the release of this mineral from the caseins due to the heat denaturing effect, different processing method employed and the numerous spices used. the high mineral content of metata cheese is of significant importance from nutritional point of view in that it can be used to combat malnutrition (mineral deficiency) which is prevalent among the general public in developing countries such as ethiopia. table 3. the mineral profile of traditional cheese varieties (mean±se) (n=216). cheese varieties minerals sampling sources metata ayib hazo phosphorus (mg/100 g) dp 174.99±1.47a 126.48±1.64b 126.15±2.42b dc 175.68±1.63a 126.74±2.64b 125.22±2.44b dr 175.60±1.02a 125.17±2.04b 124.26±3.04b calcium (mg/100 g) dp 52.44±2.40a 40.47±0.30b 40.65±0.70b dc 51.46±1.28a 39.68±1.18b 41.73±1.28b dr 52.28±1.99a 41.23±2.99b 43.91±0.99b magnesium (mg/100 g) dp 43.75±0.36a 8.27±0.36b 8.24±0.26b dc 44.21±0.46a 8.17±0.66b 8.19±0.26b dr 43.59±0.51a 8.29±0.11b 8.12±0.71b sodium (mg/100 g) dp 338.73±2.34a 42.97±2.64b 41.03±1.65b dc 348.15±4.22a 42.71±4.82b 42.87±3.42b dr 348.36±4.74a 41.88±3.74b 43.60±3.75b potassium (mg/100 g) dp 200.83±3.34a 81.58±4.33b 80.75±4.54b dc 201.05±1.25a 83.91±4.27b 82.65±4.45b dr 200.31±2.34a 82.66±4.31b 81.28±3.31b note: dp = dairy producers, dc = dairy cooperatives, dr = dairy product retail shops and kiosks, n = sample size, a,b means with the different superscript letters in a row for each mineral under the three sampling sources and cheese varieties are significantly different (p<0.05). 3.3. sensory evaluation of metata, ayib and hazo cheese varieties consumer acceptability of metata, ayib and hazo traditional cheese are presented in table 4. metata cheese samples had significantly (p<0.05) higher taste, color, aroma, texture, appearance and overall acceptance score than ayib and hazo cheese varieties. the average taste score for metata cheese samples observed in the current study is in agreement with the findings of regu et al. (2016) who reported that inclusion of one percent garlic powder treated cottage cheese samples had a taste scores of 4.62. the higher taste score of metata cheese samples observed in the present study could be attributed to various spices added during processing that resulted in strong flavor and acceptable taste. flavor perception is critically influenced by type of starter culture, level and proteolytic activity of coagulating enzyme, curd washing, ripening condition and rate of curd cooling (guinee and kilcawley, 2010). the average color score of metata cheese samples found in the present study is comparable with the report of marilda et al. (2013) who reported color score of 4.41 for marajo cheese manufactured from buffalo milk and cow milk. this might be due to colour change from white to blue mold during ripening of metata cheese. according to carpino et al. (2004) cheese color depends on milk fat colour and the content of fat itself. the aroma value of metata cheese variety observed in the present study is in agreement with the findings of el-aziz et al. (2012) who reported that cheese made from buffalo milk fortified with ginger extract had the lowest aroma scores. soryal et al. (2004) reported that the concentrations of free fatty acids mostly short chain fatty acids in cheese significantly influence cheese flavor and aroma. too much free fatty acid causes a nasty, sour and unpleasant taste to cheese. the higher aroma score in metata cheese might be attributed to the inherent property of different spices used during mitiku and aleme properties of traditional cheese varieties in eastern gojjam 191 processing, which might have imparted pleasant aroma to the cheese. texture of cheeses is related to a complex interaction between chemical composition and ripening parameters. the differences in moisture content may be the possible reason for the differences in cheese hardness (anka et al., 2016). texture is an essential feature of food as it influences processing, handling and shelf life as well as customer preferences for the product (karadbhajne and bhoyarkar, 2010). kumar and srinivasan (2011) reported that texture of cheese might be affected by water binding capacity due to the nature of protein. however, karadbhajne and bhoyarkar (2010) reported that fat, cheese yield, storage period and moisture content as well as coagulants plays an important role in cheese texture. the appearance scores of metata cheese samples observed in the present study is in agreement with gehan and samah (2014) who reported appearance scores of kareish cheese manufactured by various ways as 4.3-4.7. the overall acceptability of metata cheese samples observed in the present study agrees with bandyopadhy et al. (2007) who reported that a sandash (antioxidant enriched dairy product) fortified with ginger had good acceptability scores. the higher acceptability of metata cheese might be attributed to the various spices used during its preparation. the high consumer acceptability of metata cheese is important in that it will facilitate the scaling-up of metata cheese production to commercial level in the future. table 4. consumer acceptability of traditional cheese varieties (mean ± se) (n = 58). cheese varieties variables sampling sources metata ayib hazo taste dp 4.46±0.24a 3.50±0.25b 3.62±0.15b dc 4.48±0.23a 3.48±0.21b 3.58±0.29b dr 4.47±0.17a 3.46±0.37b 3.56±0.37b color dp 4.56±0.14a 3.65±0.35b 3.58±0.35b dc 4.31±0.29a 3.76±0.19b 3.58±0.24b dr 4.31±0.14a 3.65±0.17b 3.56±0.27b aroma dp 4.74±0.33a 3.48±0.22b 3.41±0.55b dc 4.85±0.26a 3.45±0.31b 3.44±0.36b dr 4.75±0.15a 3.46±0.45b 3.48±0.42b texture dp 4.84±0.15a 3.58±0.35b 3.54±0.22b dc 4.86±0.19a 3.54±0.41b 3.55±0.24b dr 4.83±0.17a 3.53±0.27b 3.56±0.33b appearance dp 4.57±0.37a 3.37±0.21b 3.39±0.45b dc 4.49±0.35a 3.35±0.11b 3.34±0.67b dr 4.47±0.39a 3.38±0.14b 3.36±0.68b over all acceptability dp 4.27±0.25a 3.53±0.34b 3.51±0.55b dc 4.31±0.39a 3.49±0.48b 3.48±0.65b dr 4.33±0.17a 3.48±0.49b 3.47±0.77b note: dp = dairy producers, dc = dairy cooperatives, dr = dairy product retail shops and kiosks, a, bmeans with the different superscript letters in a row for each variable (sensory attribute) under the three sampling sources and cheese varieties are significantly different (p<0.05), n = total number of panelists. 4. conclusions this study we found that metata cheese variety is rich source of fat and crude protein as well as minerals (calcium, phosphorous, magnesium, sodium and potassium). moreover, lower moisture content of this cheese variety attributed to its longer shelf life. the consumer acceptability value of metata cheese variety was also significantly higher than that of ayib and hazo cheese varieties. in general metata cheese variety is highly nutritious and acceptable by the consumer than ayib and hazo cheese varieties due to its good gross chemical composition, high-mineral profile and acceptable organoleptic properties. therefore, nutritional value and acceptability of metata cheese variety calls for scaling-up of this cheese production to commercial level by developing standardized manufacturing protocols. 5. acknowledgements the authors are grateful to ethiopian institute of agricultural research for research grant, ethiopian food, medicines and health care administration and control authority, and bless agri-food laboratory services for providing laboratory facilities for laboratory analyses. mitiku and aleme east african journal of sciences volume 13 (2) 185-194 192 6. references adetunji, v. o. and babalo, o. o. 2011. a comparative assessment of the nutritional contents of ‘wara’ a west african soft cheese using calotropis procera and cymbopogon citratusas coagulants. african journal of food agriculture nutrition and development, 11 (7): 55745585. anka, p. v., snezana, p., anka, k., marija, j., milka, p. and branislava, b. 2016. production, composition and characteristics of organic hard cheese. biotechnology in animal husbandry, 32 (4): 393-402. arenas, r., gonzalez, l., bernardo, a., fresno, j. m. and tornadijo, m. e. 2004. microbiological and physico-chemical changes in genestoso cheese, a spanish acid curd variety, throughout ripening. food control,15 (4): 271-279. assefa, e., beyene, f., and santhanam, a. 2008. isolation and characterization of inhibitory substance producing lactic acid bacteria from ergo, ethiopian traditional fermented milk. livestock research for rural development volume 20 no. 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journal of clinical nutrition, 79 (5): 907-912. mitiku and aleme east african journal of sciences volume 13 (2) 185-194 194 ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2019) volume 13 (2) 121-134 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: diribuz07@gmail.com attribution-noncommercial 4.0 international license. combining ability of highland adapted double haploid maize inbred lines using line x tester mating design diribu tesfaye1*, demissew abakemal2, and ermias habte1 1ambo university, p. o. box 19, ambo, ethiopia 2ethiopian institute of agricultural research, ambo-pprc ethiopia, p.o. box 37, ambo, ethiopia abstract: development of inbred lines is a routine activity in hybrid maize breeding program. understanding the relative importance of general (gca) and specific (sca) combining ability effects for different traits of newly developed maize lines is of paramount importance to design future breeding strategies for the development of hybrid. there are several types of mating designs available to study the combining abilities of maize inbred lines, of which line x tester mating scheme is one used to determine the combining abilities and also to categorize the lines into heterotic groups. the objectives of the study were, therefore, to estimate gca and sca of newly developed highland maize lines using line x tester mating design, to identify best promising hybrid crosses with desirable traits for further breeding and cultivar development, and to identify the heterotic groups of the lines involved in the crosses. twelve lines and four testers were involved in the study. a total of 48 testcrosses along with two checks were made available for evaluation across locations. an alpha lattice design (10x5) with two replications at each location was used. two lines (l6 and l5) showed highly significant and positive gca effects for grain yield. besides, l6 also revealed positive gca effects for the other yield related traits such as number of ears per plant (nepp), number of rows per ear (nrpe), number of kernels per row (nkpr) and ear diameter (ed). on the other hand, crosses l7xt2, l8xt4, and l9xt1 had positive and significant sca effects for grain yield. the lines and crosses with positive and significant gca and sca effects, respectively; could be selected for use in highland maize hybrid or/and synthetic cultivar development. the testers clearly categorized l3 and l6 into their respective heterotic groups in a similar pattern unlike the other lines which requires the application of molecular markers for further verification. keywords: general combining ability; specific combining ability; line; tester 1. introduction maize (zea mays l., 2n=2x=20) is among the world’s most widely grown cereals indicating its adaptability to a wide range of environments. maize is an important source of food and nutritional security for millions of people in the developing world, especially in subsaharan africa (ssa) and latin america. it is a staple food in many of the ssa countries and is commonly grown by resource poor small-scale farmers in rural areas (shiferaw et al., 2011). the need for food security and the diverse agro-climatic conditions in ethiopia have encouraged the majority of subsistence farmers to grow various crops. one major shift is that over the past 20 years, the area dedicated to maize cultivation in ethiopia has expanded progressively (demissew et al., 2013). increase in maize production and productivity can be achieved by identifying elite parental materials which can be used to develop high yielding hybrids by using suitable mating designs (liaqat et al., 2015). there are several types of mating designs available to study the combining ability of maize lines; of which line x tester mating scheme is one. a line x tester mating design involves the crossing of a number of selections, lines, or clones to a common parent (tester) (kempthorne, 1957). the tester is used as male parent and lines which are used as females to be tested are either male-sterile or self-incompatible, or are emasculated before pollen shed to prevent selfing. for line evaluation, a desirable tester is defined by matzinger (1953) as one that combines the greatest simplicity in use with the maximum information on performance to be expected from tested lines with respect to general and specific combining abilities. apart from evaluation of cross performances at early stages of line development, several studies were conducted to study general combining ability (gca) and specific combining ability (sca) of lines for different traits using line x tester. the design is useful in deciding the relative ability of female and male lines to produce desirable hybrid combinations (kempthorne, 1957). it also provides information on genetic components and enables the breeder to choose appropriate breeding methods for cultivar development. it is always important for any breeding program to generate such information for any new batch of lines generated or received outside of the program (panhwar et al., 2008). understanding the relative importance of general (gca) and specific combing ability (sca) effects for different traits of newly developed lines are of paramount importance to diribu et al. east african journal of sciences volume 13 (2) 121-134 122 design future breeding strategies for the development of hybrid and or synthetic varieties (joshi et al., 2002). heterotic classifications generated from a line x tester analysis can assist in determining the relationship existing among the different lines (joshi et al., 2002; sharma et al., 2004). a number of maize inbred lines have been developed from maize breeding programs in ethiopia (bayisa et al., 2005; dagne et al., 2007; worku et al., 2008). however, there has been limited information on the combining ability effects and heterotic classification of the newly developed lines, which necessitated this study. therefore, the objectives of this study were: (1) to determine general combining abilities (gca) and specific combining abilities (sca) of newly developed highland maize lines using line x tester mating design and (2) to identify the heterotic groups of the newly developed lines for further use in the breeding program. 2. materials and methods 2.1 description of the study sites the experiments were conducted in the main cropping season of 2015 at ambo plant protection and holetta agricultural research centers. ambo is located at 8057n latitude and 3807e longitudes and an altitude of 2225 meters above sea level (masl). the long-term average annual rainfall at ambo is 1115 mm with minimum and maximum temperature of 11.70c and 25.40c, respectively. the soil type of the experimental site of ambo is heavy vertisol. the location at holetta research center is 9000n latitude and 38030‘e longitude and an altitude of 2400 meters at sea level with soil type of nitosol. the area receives an average annual rainfall of 1065 mm, with minimum temperature 6.40c and maximum 22.10c. both locations represent the highland sub-humid maize growing agro-ecology of ethiopia. 2. 2 experimental materials there were twelve lines and four testers used in the present study. the testers were fs59 (tester-1), fs67 (tester-2), ec573 (tester3), and kitale synthetic ii (tester4); the first two were lines and while the later two were populations (table 1). originally, tester-1 and tester-2 were derived from tester-3 and tester-4 respectively, while the twelve lines were derived from either of the population testers. the lines were introduced to ethiopia from cimmyt-kenya in 2014 and test crossed with the aforementioned four testers. a total of 48 lines x tester crosses constituted from twelve lines and the four testers were made available for evaluation in 2015 cropping season. these 48 f1 crosses and two standard checks (amh851and amh850) were used for this study. 2.3. experimental design and field management an alpha lattice experimental design (10x 5) was used with two replications at each location. and also one replication consisted of five incomplete blocks within main blocks. the spacing used was 75cm between rows and 25cm between plants. each plot consisted of a single 5.25m long row. each entry had an equal chance of being randomly placed to any plot per block within a replication. planting was done on 26th of may 2015 manually using two seeds per hill after reliable moisture level of the soil had been attained to ensure good germination as well as seedling development. later on, 35 days after planting, maize seedlings were thinned out to one plant to get 53,333 maize plant populations per hectare. the recommended rate-150 and 200 kg ha-1 dap and urea-was used, respectively. band application of phosphorous fertilizer in the form of diammonium phosphate (dap) was carried out at planting time. urea was applied in two splits-at 40 days and 70 days after planting. all other agronomic management practices were done, accordingly. 2.4 data collection days to silking (sd), days to tasseling (ad), and days to maturity (dm): the number of days from planting to when 50% of the plants in a plot produced 2-3 cm long silk, started shedding pollen and the plants in a plot reaches physiological maturity respectively. plant height (ph), expressed in cm, measured from the base of a plant to the insertion of the first tassel branch of the same plant, ear height (eh), measured in cm from the base of a plant to the insertion of the top most ear of the same plant). ear length (el) was measured as the length of the ear from the base to tip, ear diameter (ed) was measured at the mid-way along ear length, and number of ears per plant (nepp) is number of ears with at least one fully developed grain divided by the number of harvested plants). number of rows per ear (nrpe) and number of kernels per row (nkpr) were randomly taken as averages. thousand kernel weight (tkwt) is weight in grams of 1000 random kernels was weighed from each plot using sensitive balance and was adjusted to 12.5 % moisture level. ear aspect (ea) was taken by judging the phenotypic appearance of the ear by giving a number scale from 15. grain yield (gy) was weighed in kg/plot and adjusted to12.5% moisture content and 80% shelling percentage and then converted to tones/ha and the percentage of bare-tip ears recorded for husk cover (hc). root lodged (rl) percentage of plants lodged per plot was recorded. 2.5 statistical procedures analyses of variance anova per individual location across location ware carried out using the proc glm procedure of sas 9.3(sas, 2002). genotypes were considered as fixed factor while replications and diribu et al. combining ability of highland adapted double haploid maize 123 incomplete blocks within replications were considered as random factors. when significant difference was detected among entries at each location, a combined anova was conducted. the combined analyses across locations were done for characters that showed statistically significant differences among the genotypes at two of the locations. partitioning of the mean squares due to crosses in to lines (gcal), testers (gcat) and line x tester interactions (scalxt) (kempthorne, 1957) was also done using sas (ver. 9.3) software program. checks were not included in the combining ability analyses. the combining ability analyses for grain yield and other agronomic traits were done using the line x tester linear model as follows: yijk= µ + r(ek) + ek + li + tj + (l x t)ij + (l x e)ik + (t x e)jk + (l x t x e)eijk + ԑijk; where yijk is measured trait of the genotype of ith line crossed to jth tester evaluated in r replications across k environments; µ is grand mean; r(ek) is the effect of replication nested within the k environments; l and t represent average effects of lines and of testers, respectively, which is equivalent to gca effects of lines and testers, respectively; l x t = line x tester interaction effects that is equivalent to the sca effects of the crosses; e is the environmental main effects; l x e, t x e, and l x t x e are the interactions of the lines, testers and the lines x testers with the environments, and ԑijk is the random experimental error. the gca of lines (gcal) and testers (gcat), and scalxt of crosses and their standard errors were estimated (dabholkar, 1992). inbred line that expressed negative sca effects when crossed to a certain tester implied that they are categorized under the same heterotic group with the tester; however, if the same line manifests positive sca effect with the same tester, it is classified into opposite heterotic group (vasal et al., 1992). data transformation for percentage data was done before analysis for traits such as husk cover, stalk and root lodging. arcsine transformation method: y’ = arcsin √ y for husk cover and square root transformation methods: y’ = √ y + 0.5 for stalk and root lodging where y’ is the transformed value, and y is the original value. table 1. descriptions of the 12 highland maize lines and 4 testers used for the research. serial no. code pedigree source role in the study 1 l1 (zewac1f2-134-4-1-b-1-b*4/cml540)dh-8-b-# cimmyt line 2 l2 (g16bnseqc4-(f22x1)-2-3-1-b*4-b/zm523b-29-2-1-1-bbb)dh-7b-# cimmyt line 3 l3 zm523b-29-2-1-1-bbb-b-b-# cimmyt line 4 l4 (zewac2f2-183-2-bbb-b/cml542) dh-3-b-# cimmyt line 5 l5 (cml545/cml505) dh-10-b-# cimmyt line 6 l6 (cml545/cml505) dh-29-b-# cimmyt line 7 l7 (cml545/cml505) dh-44-b-# cimmyt line 8 l8 (zewac2f2-183-2-bbb-b/[inta-2-1-3/inta-60-1-2]-x-11-6-3bbb-b) dh-11-b-# cimmyt line 9 l9 (zewac2f2-183-2-bbb-b/[inta-2-1-3/inta-60-1-2]-x-11-6-3bbb-b) dh-17-b-# cimmyt line 10 l10 (zewac1f2-151-6-1-b-1/zewac1f2-300-2-2-b-1) dh-3012-b-b-# cimmyt line 11 l11 (cml505/[inta-2-1-3/inta-60-1-2]-x-11-6-3-b) dh-3016-b-b-# cimmyt line 12 l12 (inta-f2-192-2-1-1-1-b*9/cml505-b) dh-3021-b-b-# cimmyt line 13 t1 fs59 ambo-hmbp* tester 14 t2 fs67 ambo-hmbp tester 15 t3 ec573 ambo-hmbp tester 16 t4 kitale synthesis ii ambo-hmbp tester 17 49 amh851 ambo-hmbp check 1 18 50 amh850 ambo-hmbp check 2 note: *hmbp –highland maize breeding program 3. results and discussions 3.1 combining ability analysis the results from combined combining ability analyses of variances for grain yield and yield related traits are presented in table 2. the combined analyses of variance across locations revealed that mean square due to location had non-significant difference for ph, nrpe and el while all the rest traits showed significant differences (p < 0.01) indicating that the two locations differed in their environmental conditions. these findings agreed with those reported by aly and amer (2008), aly et al. (2011) and mousa and aly (2012). according to gezahegn (2005), however, significant mean squares of locations for ph across four locations were reported. the mean squares due to diribu et al. east african journal of sciences volume 13 (2) 121-134 124 crosses exhibited highly significant differences (p < 0.01) for most of the traits with the exception of ear length. this indicated that the crosses were sufficiently different from each other for these traits and hence, selection is possible to identify the most desirable hybrids. in line with this study several investigators reported the existence of highly significant differences among the maize crosses for almost all traits under study (parvez et al., 2007; aly and amer, 2008; zoran et al., 2012). the line mean square values were highly significant for all traits indicating that the existence of variability among the set of lines used in this research (table 2). tester mean squares for most traits were also showed highly significant difference (p < 0.01). the significance of mean squares due to lines and testers (gca) for most traits indicated the prevalence of additive types of gene actions in the expression of these traits. in support of the present investigation, reza et al. (2013) observed that lines and testers had significant mean squares in single cross maize hybrids for all traits in the study. mean squares from the combined analysis for lines x tester (sca) interaction also showed highly significant differences for most traits including gy, ad, sd, eh, hc, nkpr, ed, and tkw indicating the overwhelming contribution of dominant effect type of gene action in these traits. however, the proportion of gca sum of squares to sca for all the traits were greater than unity indicating that the contributions of additive gene effects were more important than non-additive gene effects in this study. therefore, lines used in the present study were diverse, resulting in the expression of variation among genotypes for various traits. earlier investigators also found that line x tester mean squares were significant for grain yield and yield related traits across locations (parveez et al., 2007; aly and amer, 2008). lines x location mean squares (table 2) were significant for traits, but the magnitudes were consistently smaller than the respective line mean squares obtained from individual location analysis. this suggests the need of selecting different parental lines for hybrids in specific environment. trait which showed non-significant variations for line x location interaction were gy, ph, pa, md, nrpe, el, and ed. similar results of combined analyses were previously reported by various researchers (bayisa et al., 2008; kanyamasoro et al., 2012; mousa and aly, 2012) using different sets of maize inbred lines. however, this result contradicts with ibrahim and mousa (2011) reports of significant interaction of line x location mean squares for gy. diribu et al. highland adapted double haploid maize inbred mating design 125 table 2. mean squares of combining ability from combined analysis for grain yield and other related traits of 48 line x tester crosses evaluated across two locations(ambo and holetta) in 2015. source of variation df gy ad sd ph eh pa ea rl hc md nepp nrpe nkpr el ed tkw location 1 15.52** 20708.52** 26861.67** 405.42 2275.63** 5.03** 3** 1.22** 25986.75** 2227.68** 8.97** 1.06 781.25** 9.29 199.92** 332868.55** rep (location) 1 4.3* 28.07** 45.38** 1371.71** 1362.52** 0.01 0.31 1.0** 33.26 75.08* 0.003 0.32 4.63 4.56 1.61 1986.9 crosses 47 5.65** 45.00** 56.08** 1119.43** 1005.49** 0.51** 0.82** 0.22** 848.11** 51.68** 0.11** 3.80** 18.25** 10.49 24.44** 5644.88** line (gcal) 11 11.66** 131.42** 133.27** 1378.09** 2411.20** 1.53** 1.57** 0.28** 2340.95** 76.95** 0.28** 5.92** 45.01** 15.02* 40.4** 11999.32** tester (gcat) 3 22.04** 141.5** 300.01** 10010.17** 4843.47** 0.88** 5.11** 0.79** 1397.76** 98.39** 0.09 28.1** 4.76 12.43 134.7** 5174.34* line*tester (scalxt) 33 2.15** 7.42** 8.18** 224.97 188.01** 0.13 0.19 0.15 300.54** 39 0.05* 1.15 10.56** 8.81 9.09** 3569.63** crosses*location 47 1.31 3.52** 5.71** 232.0 79.77 0.16 0.16 0.21** 333.2** 32.27 0.04** 1.19 10.56** 7.34 2.91 2988.00** line* location 11 1.19 6.89** 12.52** 355.11 174.7** 0.139 0.42** 0.37** 670.95** 26.39 0.01** 1.19 11.97* 9.19 1.83 4459.05** tester*location 3 0.19 3.45 10.31* 259.85 41.28 0.31 0.08 0.01 361.72* 54.56 0.05** 0.57 20.65** 11.90 3.91 824.49 line*tester*locations 33 1.46 2.4 3.02 188.43 51.63 0.15 0.08 0.17 218.03** 32.2 0.02 0.74 9.17* 6.31 3.18 2694.34* pooled error 94 1.13 1.64 3.26 184.08 65.76 0.20 0.14 0.12 112.66 25.51 0.02 0.97 5.83 7.65 2.54 1623.48 r2 gm 0.76 8.23 0.99 95 0.98 97.47 0.79 243.97 0.90 132.4 0.66 2.99 0.79 3.24 0.67 0.93 0.88 25.79 0.72 176.69 0.87 1.35 0.72 13.25 0.79 36.8 0.54 17.10 0.86 44.65 0.82 346.73 cv% 13.33 1.34 3.26 5.76 6.12 14.97 11.72 37.5 41.04 2.85 11.18 7.45 6.54 16.17 3.57 11.62 note: *and ** refers to significant at p < 0.05 and p < 0.01 respectively, gy=grain yield (t h-1), ad=days to 50% anthesis, sd=days to 50% silking, ph=plant height(cm), eh=ear height (cm), pa=plant aspect (1-5 scale), ea=ear aspect (1-5 scale), rl=root lodging (%), hc=husk cover (%), md=days to 50% maturity, nrpe=number of row ear-1 (number), nepp= number of ear plant-1 (number), nkpr= number of kernel row-1 (number), el=ear length (cm) and ed= ear diameter (cm), tkw=thousand kernel weight(g), of the genotypes used. diribu et al. east african journal of sciences volume 13 (2) 121-134 126 3.2 general combining ability effects the estimates of gca effects of lines for grain yield and yield related traits combined across two locations are presented in table 3. accordingly, l6, l5 and l9 showed highly significant and positive gca effects for gy. whereas l2, l7 and l10 had significantly negative gca effects for gy. consequently, the lines with positive gca effect could be selected as good combiners for grain yield improvement. gca of t1 and t4 revealed positive and highly significant effects in the combined analysis for grain yield. in contrast to this, t2 and t3 revealed negative and highly significant gca effects. in line with the current study, several authors reported both positive and negative significant gca effects of experimental maize hybrids for grain yield (ahmad and saleem, 2003; pswarayi and vivek, 2008; legesse et al., 2009; mosa, 2010; zeleke and tuna, 2010). the estimates of lines’ gca effects varied from -6.28 (l10) to +3.65(l9) and -5.97(l10) to +3.83(l9) for ad and sd, respectively (table 4). l3, l4, l6, l7 and l9 had significant positive gca effects for both traits while l1, l8 and l10 were highly significant and negative gca effects for similar traits. aminu and izge (2013) reported highly significant negative and positive gca effects among the tested lines for days to tasselling and silking. lines showed varied trends of significant gca effects for ph in the combined analysis (table 3). l10 (-21.59) had negative and highly significant gca effects for ph suggesting that this line could contribute for shorter stature trait in the improvement of maize for lodging resistance. on the other hand, l6 (+13.46) and l3 (+11.77) had positive and highly significant gca effects for the same traits. most of the lines with significant gca effects for eh also revealed similar trend for ph with the exception of l5 (+7.53) that showed contrasting effects (table 3). similar findings reported short ph and eh reduced lodging in maize (mosa, 2010; zeleke and tuna, 2010; rahman et al., 2012). gca estimates for ea from the combined analysis ranged from -0.43 to +0.34. l3, l9, and l4 revealed a high and negative gca effect which indicated a good ear character in this regard and could thus be used in breeding programs for the improvement of germplasm for the trait. similar lines revealed significant positive and negative gca effects for pa and ea as well. therefore, the lines with negative gca can be good combiners for pa, while the lines with positive gca effects may be poor combiners for the trait. in support of this study, girma et al. (2015) reported positive and negative gca effects for ear aspect at a single location evaluation. in contrast, wende (2013) found two lines with positive gca effects among nine maize inbred lines evaluated across seven environments for the same trait. 3.3. specific combining ability effects the estimates of specific combining ability effects across locations in respect to the 48 hybrids are presented in table 4. of all the 48 crosses evaluated, l1xt1, l7xt4 and l4xt4, expressed negative and significant sca effects for grain yield, which is unwanted as these crosses showed a tendency to reduce grain yield performance. in contrast, crosses l7xt2, l8xt4 and l9xt1 revealed positive and significant sca effects for gy. these crosses with high positive and significant estimates of sca effect could be selected for their specific combining ability to use in maize improvement. in this investigation, sca of gy across environments was negative for most crosses, which may be attributed from using lines with the same genetic background. sca effects could be positive with superior performance for crosses involving lines from different genetic backgrounds (betran et al., 2003b). for days to 50% anthesis, nine and four crosses showed significantly negative and positive sca effects across locations, respectively. seven and three crosses showed significant negative and positive sca effects across locations for days to 50% silking, respectively (table 4). aminu and izge (2013) reported that negative and positive sca estimates with respect to twenty hybrids for ad and sd in maize across environments. the sca effects showed that crosses l2xt1, l10xt4 and l11xt2 revealed negative and highly significant values for ph suggesting the possibility of inheritance of shortness in maize plants to develop genotypes tolerant for lodging. these results are in contrast with those obtained by aly (2013), who reported positive and negative significant sca effect of top-crosses studied across two locations for the trait. crosses l1xt1, l1xt2, l4xt2, l2xt3, l5xt1, l6xt3, l7xt3 and l10xt4 revealed negative and highly significant sca effect for eh. in contrast to this, seven crosses revealed positive sca effects for the trait. in line with this study, aminu and izge (2013) reported that negative and positive sca estimates with respect to twenty hybrids for eh in maize across environments . diribu et al. highland adapted double haploid maize inbred mating design 127 table 3: general combining ability effects (gca) of the 12 lines and four testers for grain yield and other yield related traits combined across two locations (ambo and holetta) in 2015. traits line gy ad sd ph eh pa ea rl hc md nepp nrpe nkpr el ed tkw l1 -0.18 -2.28** -2.53** -0.16 -11.58** 0.16* -0.15 0.01 -16.7** 1.36 0.05 -0.52* -0.86 -1.39 -1.64** 14.31 l2 -1.07** -0.78 -0.53 -7.66 0.72 0.06 0.25 0.21 14.95* 0.17 -0.06 0.13 0.43 -0.4 -2.05** -48.98** l3 0.44 3.28** 1.77* 11.77** 11.91** -0.27** -0.43** 0.2 -16.8** 3.8** 0.04 -0.94** 0.17 0.9 -0.29 49.92** l4 -0.51 1.65** 2.58** 3.58 5.91 -0.18* -0.3* -0.03 -14.62* -2.07 -0.02 0.05 4.35** 0.03 0.01 -11.15 l5 0.9** 0.65 -0.41 -2.22 7.53* -0.18* 0.19 0.02 9.76 1.55 0.11* -0.23 -2.17** 0.16 -0.15 43.3** l6 1.88** 2.4** 2.58** 13.46** 18.84** -0.08 -0.15 -0.09 3.24 2.61* 0.28** 0.71** 1.65* -0.56 2.19** -18.16 l7 -0.98** 1.53* 2.77** -1.41 5.03 -0.08 0.25 0.16 -1.8 0.61 -0.11* -0.46 -0.65 2.5** -0.03 5.07 l8 -0.08 -3.03** -2.97** -2.84 -6.96* 0.34** 0.34* -0.07 10.12 -2.51* -0.04 0.01 -1.14 -0.3 0.71* 10.314 l9 0.55* 3.65** 3.83** 3.65 -0.52 -0.27** -0.43** -0.16 -6.42 -1.38 -0.01 0.51 -0.19 -0.01 2.04** -7.95 l10 -0.81** -6.28** -5.97** -21.59** -28.71** 0.78** 0.34* -0.11 10.23 -2.88* 0.08 0.09 -1.26 -1.07 -2.54** -20.93 l11 -0.18 -0.15 -1.09 -3.53 -5.15 -0.24** -0.24 -0.15 -6.34 0.98 -0.17** 1.22** 0.1 0.06 2.13** -13.56 l12 0.06 -0.65 -0.03 6.96 2.97 -0.02 0.31* 0.01 14.48* -2.26 -0.13 -0.57* -0.41 0.08 -0.36 -2.17 se(gi) 0.26 0.62 0.84 4.51 3.16 0.08 0.15 0.14 6.2 1.22 0.05 0.26 0.82 0.72 0.32 15.98 tester t1 0.83** -0.94** -0.76 3.75 1.6* -5.98* -0.34** -0.06 -0.01 -1.23 0.02 0.05 0.02 0.12 -0.07 5.06 t2 -0.46** -0.86** -2.16** -18.82** -12.83** 1.06 0.01 -0.08 -0.01 1.19 0.03 -1.08** -0.36 -0.12 -1.85** 9.05* t3 -0.62** -0.76** -0.68 -0.93 -0.42 6.83** 0.42** 0.2** 0.03** -1.23 -0.01 0.36** -0.06 -0.58 -0.28 -14.67** t4 0.25** 2.57** 3.6** 16** 11.61** -1.91 -0.06* -0.04 -0.02* 1.28 -0.05 0.66** 0.4 0.58 2.21** 0.55 se(gi) 0.05 0.23 0.4 2.01 0.8 2.37 0.03 0.07 0.01 0.92 0.04 0.09 0.56 0.43 0.24 3.58 note: *and ** refers to significant at p < 0.05and at p < 0.01 respectively, l1-12 = line, t1-4= tester, gy=grain yield (t h-1), ad=days to 50% anthesis, sd=days to 50% silking, ph=plant height (cm),eh=,ear height (cm), pa=plant aspect (1-5 scale), ea=ear aspect (1-5 scale), rl=root lodging (%), hc=husk cover (%), md=days to maturity, nepp= number of ear plant-1 (number), nrpe=number of row ear-1 (number), nkpr=number kernel row-1 (number), el=ear length (cm) and ed= ear diameter (cm), tkw=thousand kernel weight (g), of the genotypes used; see table 1 for descriptions of lines and testers codes diribu et al. east african journal of sciences volume 13 (2) 121-134 128 sca effects for pa varied from -0.38 to +0.55. cross l3xt2 manifested negative and significant sca effect for pa indicating that it was good specific combiner. on the other hand, the cross combinations of l1xt2 and l3xt1 expressed positive and significant sca effects. hybrids such as l3xt4, l8xt1, l9xt2 and l11xt3 had significantly negative sca effects for ear aspect (ea) while l2xt1, l3xt3, l7xt1, and l11xt4 had significantly positive sca effects for the same trait (table 4). girma et al. (2015) obtained negative and positive sca effects for ear aspect, while wende (2013) reported similar results for plant aspect. crosses of l1xt3 and l2xt3 showed positive and highly significant sca effects for root lodging (rl) suggesting that they were undesirable crosses. similarly, bhatnagar et al. (2004) reported significant sca effect for rl. cross l9xt2 had significant and negative sca effect for hc. other hybrids with significant and positive sca effects for hc included l7xt3, l5xt4 and l12xt1. these results were at par with the findings of girma et al., (2015) who reported positive and negative significant sca effects of maize crosses for hc. the sca effects for md ranged from -5.82 to +6.4. crosses l6xt1, l10xt2 and l11xt4 manifested negative and significant sca effects indicating that these crosses were good specific combinations for early maturing. hence, such cross combinations could effectively be exploited in hybrid breeding program in maize research for reduced days to maturity. on the other hand, cross combinations l6xt2 and l9xt4 expressed positive and significant sca effects for days to 50% maturity, which were undesirable as these crosses showed a tendency to mature late (table 4). this result disagrees with the findings of melkamu et al. (2013) who reported nonsignificant qpm crosses for the same trait at a single location evaluation. twelve crosses showed significant estimates of sca effects for nepp (table 5). cross l1xt3, l2xt2, l5xt4, l6xt1, l7xt1, l8xt4, and l11xt4 were good positive specific combiners while l1xt2, l5xt1, l6xt4, l7xt4 and l8xt3 were found poor. the highest sca effect for gy in the combined analysis was obtained from l8xt4 cross. it was, therefore, demonstrated that high yielding crosses showed high sca values, indicating the importance of sca effects in predicting hybrid performance for each trait. this observation is similar with the study of betran et al. (2003b) and gezahegn (2005) who suggested that sca predicts hybrid performance for nepp. sca estimates of combined data of the crosses ranged from -0.9 to +0.84 for nrpe. crosses l1xt3, l4xt2, l11xt3 and l12xt4 showed positive and significant sca effects which was attractive for this trait because genotypes with good sca can contribute to increased grain yield in hybrid combinations. on the other hand, l2xt2, l3xt3 and l11xt4 revealed negative and significant sca effects. however, aly (2013) reported non-significant sca among twenty-two top-crosses studied across two locations for nrpe. only cross l7xt4 revealed positive and significant effects for number of kernels per row (nkpr). in contrast to this investigation, aly (2013) reported positive and negative significant sca effects among twenty-two top-crosses studied across two locations for number of kernels per row. eight crosses showed positive and significant estimates of sca effects for ed (table 4). cross l1xt1, l2xt4, l4xt2, l7xt3, l9xt2, l10xt2, l11 xt1 and l12xt4 were found with good positive sca while nine crosses were the poorest of all for the same trait. these results contradict with the results of aly (2013) who reported non-significant ed. the highest positive sca effect for the gy was contributed by l3xt3 from the across locations analysis. in general, it was demonstrated that high yielding crosses showed high sca values in this study indicating the importance of sca effects in predicting the performance hybrids. ear diameter and number of kernel rows per ear could be given attention during selection for grain yield improvement in maize (manivannan, 1998). sca effects of el and tkw ranged from -2.39 to 6.04 and -75.81 to -45.62, respectively (table 4). cross l2xt2 and l7xt4 expressed significant negative sca effects and were found to be poor combiners for tkw while cross l7xt4 showed positive and highly significant effect for el. these results were in agreement with the investigation of pal et al. (1986) who reported positive and negative significant sca effects for tkw, and aly (2013) found similar results for ear length. table 5 shows putative heterotic grouping of the lines used. in general, from the sca values in table 5, one can depict that the four testers: tester-1(fs59), tester-2(fs67), tester-3(ecu573) and tester-4(kitsyn ii) of the two major heterotic groups (ecuador and kitale) used in the highland maize breeding program were able to categorized seven of them (l2, l3, l4, l6, l8, l9, and l12) among the 12 lines into the already known heterotic groups (ecuador and kitale), whereas there was no clear discrimination in to heterotic groups for the remaining five lines (l1, l5, l7, l10 and l11) by the testers. particularly, both groups of testers clearly categorized l3 and l6 into their respective heterotic groups in a similar pattern unlike for the other lines where the testers groups had not shown similar patterns of classifications, though the sca values were not statistically significant in some cases. diribu et al. highland adapted double haploid maize inbred mating design 129 table 4: estimation of specific combining ability effects of the 48 line x tester crosses for grain yield and other related traits evaluated across locations in 2015. traits crosse gy ad sd ph eh pa ea rl hc md nepp nrpe nkpr el ed tkw l1xt1 -0.01 1.32* 1.32 5.43 -6.2* -0.08 -0.22 -0.22 2.7 -0.32 -0.01 -0.17 0.29 0.41 2.53** 41.17 l1xt2 -1.08* -2.51** -2.02** -3.48 -6.72* 0.55** 0.01 -0.07 -0.29 2.48 -0.19** -0.2 -0.97 -0.56 -0.44 9.99 l1xt3 0.9 0.13 0.01 -1.13 13.6** -0.23 -0.01 0.45** -0.53 -2.57 0.15* 0.84* 0.35 0.58 -0.31 -9.89 l1xt4 0.19 1.05 0.7 -0.81 -0.68 -0.23 0.22 -0.16 -1.88 0.4 0.05 -0.45 0.33 -0.43 -1.76* -41.27 l2xt1 0.25 0.32 -0.17 -17.06** 3.73 0.01 0.36** -0.13 2.6 3.364 -0.09 0.32 2.15 1.16 -0.92 12.03 l2xt2 0.01 -0.01 0.72 8.51 -0.78 0.02 -0.14 -0.15 5.17 -3.07 0.14* -0.7* 1.19 0.33 -1.79* -75.81** l2xt3 0.19 -0.36 -0.75 -2.13 -6.95* -0.01 -0.04 0.34** 0.32 0.114 -0.001 0.17 -1.6 -0.35 0.43 29.34 l2xt4 -0.45 0.05 0.2 10.68 4.00 -0.01 -0.18 -0.05 -8.19 -0.4 -0.05 0.21 -1.74 -1.14 2.28** 34.42 l3xt1 -0.71 -0.48 1.26 -0.01 1.29 0.34* -0.06 0.33 2.73 -0.01 -0.03 -0.09 -0.25 -0.41 0.45 -20.98 l3xt2 0.71 0.92 0.66 5.82 4.02 -0.38* -0.07 -0.27 -2.6 1.05 0.1 0.54 -0.79 -0.99 0.19 -8.46 l3xt3 -0.72 -1.67* -1.56* -8.31 -4.89 0.07 0.39** 0.12 -0.4 -3.01 -0.04 -0.9* -0.16 0.35 -1.16 2.55 l3xt4 0.72 1.23 -0.35 2.49 -0.43 -0.04 -0.24* -0.19 0.27 1.96 -0.02 0.46 1.21 1.04 0.52 26.89 l4xt1 0.24 -0.11 -0.29 6.68 5.79 -0.12 0.057 0.04 1.05 -0.88 -0.05 -0.42 0.72 0.97 -0.77 5.47 l4xt2 0.45 -0.44 -1.15 -7.23 -7.97** -0.09 0.17 -0.03 -3.39 -0.32 0.05 0.71* 2.02 0.99 1.63* 31.03 l4xt3 0.56 0.19 0.11 1.36 6.35* 0.11 -0.23 0.01 -5.86 3.36 0.08 0.09 -2.44 -0.71 -0.36 -22.76 l4xt4 -1.26* 0.36 1.32 -0.81 -4.12 0.1 0.01 -0.02 8.21 -2.15 -0.08 -0.37 -0.3 -1.25 -0.49 -13.74 l5xt1 -0.89 -0.36 -0.04 -10.5 -7.57* 0.01 -0.19 0.23 -9.55 -0.51 -0.18** 0.19 0.6 -0.78 0.31 -5.59 l5xt2 -0.14 1.05 -0.15 6.32 4.40 0.15 0.04 -0.08 4.35 -3.44 0.01 0.16 -1.08 0.24 -1.62* 11.46 l5xt3 0.79 0.69 1.11 5.68 6.98* -0.13 0.14 -0.13 -2.31 2.23 0.01 0.21 0.76 -0.15 0.53 -26.25 l5xt4 0.24 -1.38* -0.92 -1.5 -3.80 -0.01 0.01 -0.01 7.52 1.71 0.16** -0.58 -0.27 0.68 0.77 20.37 l6xt1 -0.03 -1.36* -0.29 -1.94 2.35 -0.08 -0.09 0.01 -5.05 -5.82* 0.13* 0.06 1.17 0.32 0.71 4.96 l6xt2 0.12 0.55 0.34 6.89 2.58 0.05 0.39** 0.02 11.24 5.48* 0.02 -0.62 -0.69 0.43 -0.03 -13.24 l6xt3 -0.69 0.69 0.86 -4.5 -6.07* -0.23 -0.14 -0.14 -1.05 -2.07 0.02 0.25 0.63 -0.34 -0.9 -10.02 l6xt4 0.6 0.11 -0.92 -0.44 1.13 0.26 -0.15 0.1 -5.12 2.4 -0.17** 0.29 -1.1 -0.42 0.3 18.3 l7xt1 -0.01 1.76** 0.76 0.18 -0.32 -0.08 0.24* -0.24 1.03 1.92 0.15* 0.09 -2.32 -2.39* -1.98* -23.5 l7xt2 1.09* 0.67 0.66 6.76 8.1** 0.05 -0.14 0.06 -10.23 1.48 0.09 -0.26 -1.61 -2.06* 0.65 38.36 l7xt3 0.25 -3.17** -2.81** -5.63 -16.01** 0.01 -0.04 0.04 13.06* -0.57 -0.08 0.53 0.99 -1.58 1.6* 30.77 l7xt4 -1.34** 0.73 1.39 -1.31 8.19** 0.01 -0.05 0.12 -3.85 -2.84 -0.15* -0.35 2.94* 6.04** -0.27 -45.62* table 4. continued diribu et al. east african journal of sciences volume 13 (2) 121-134 130 l8xt1 -0.48 0.82 1.26 -1.38 -3.57 -0.02 -0.34** -0.13 -11.11 0.8 -0.01 -0.05 1.84 1.01 -0.99 20.3 l8xt2 -0.15 -0.76 -0.83 -0.29 -0.34 -0.13 0.14 0.14 3.46 1.61 -0.05 0.41 -1.29 0.12 1.33 -12.03 l8xt3 -0.41 -1.61* -2.06** -4.69 -5.26 0.07 0.1 -0.16 -10.3 -0.69 -0.12* -0.69 -0.84 0.67 1.22 -6.31 l8xt4 1.05* 1.55* 1.64* 6.36 9.19** 0.07 0.09 0.15 17.95** -1.71 0.19** 0.33 0.29 -1.81 -1.57* -1.95 l9xt1 1.54** -0.11 -2.04** 10.36 3.73 -0.02 0.05 -0.04 0.34 -1.32 0.02 0.28 -1.62 0.94 0.34 4.3 l9xt2 -0.67 -0.44 0.09 -10.79 -3.28 -0.01 -0.32** 0.1 -12.76* -4.51 -0.03 0.41 0.67 -0.34 1.54* 30.65 l9xt3 -0.78 1.44* 1.61* 3.30 -2.95 -0.04 0.26* -0.07 8.34 -0.57 -0.08 -0.53 1.38 0.98 -1.35 -25.85 l9xt4 -0.08 -0.88 0.32 -2.88 2.5 0.07 0.01 0.01 4.06 6.4** 0.09 -0.16 -0.43 -1.58 -0.54 -9.1 l10xt1 -0.35 0.07 -0.23 2.11 -1.07 0.04 0.02 0.12 -5.83 1.17 0.08 -0.13 -2.31 -0.88 0.01 -13.73 l10xt2 0.34 -0.26 -0.33 2.95 3.15 -0.06 -0.1 0.04 6.45 -5.01* -0.1 0.01 1.81 0.97 1.82* 21.11 l10xt3 0.03 1.63* 1.68* 7.05 8.73** 0.24 -0.01 -0.13 3.7 2.17 0.09 -0.45 -0.47 0.54 -0.09 24.12 l10xt4 -0.02 -1.44* -1.1 -12.13* -10.8** -0.22 0.09 -0.03 -4.31 1.65 -0.07 0.58 0.97 -0.62 -1.73* -31.49 l11xt1 0.29 0.44 0.64 6.05 0.8 -0.05 -0.01 0.24 6.5 1.8 -0.06 -0.26 -1.77 -0.58 1.93** 12.05 l11xt2 -0.22 0.11 0.78 -13.35* 0.58 -0.03 -0.01 0.09 9.8 1.61 -0.07 0.21 -0.54 0.18 -1.59* -21.44 l11xt3 -0.16 1.01 1.3 5.74 2.67 0.04 -0.29* -0.21 -8.78 1.3 -0.04 0.75* 1.73 0.63 0.01 -0.72 l11xt4 0.1 -1.57* -2.73** 1.55 -4.11 0.04 0.31* -0.11 -7.52 -4.71* 0.17** -0.7* 0.59 -0.23 -0.35 10.11 l12xt1 0.16 -2.3** -2.17** 0.05 0.98 0.09 0.18 -0.21 14.49* -0.19 0.06 0.19 1.5 0.21 -1.63* -36.49 l12xt2 -0.45 1.11 1.22 -2.1 -3.78 -0.13 0.04 0.14 -11.19 2.61 0.03 -0.66 1.29 0.66 -1.69* -11.63 l12xt3 0.03 1.01 0.49 3.24 3.78 0.07 -0.1 -0.12 3.83 0.3 0.01 -0.28 -0.32 -0.61 0.47 15.04 l12xt4 0.25 0.17 0.45 -1.19 -0.99 -0.04 -0.11 0.19 -7.13 -2.71 -0.11 0.75* -2.47 -0.26 2.84** 33.08 se(sij) 0.5 0.64 0.72 5.69 2.97 0.16 0.12 0.17 6.12 2.35 0.06 0.35 1.25 1.02 0.73 21.51 note: *and ** refers to significant at p < 0.05 and highly significant at p < 0.01respectively, l1-12 = line, t1-4 = tester, gy=grain yield(t h-1), ad=days to 50% anthesis, sd=days to 50% silking, ph=plant height (cm),eh=,ear height (cm), pa=plant aspect (1-5 scale), ea=ear aspect (1-5 scale), rl=root lodging (%), sl= stem lodging (%), hc=husk cover (%), md=days to maturity, nrpe=number of row ear-1 (number), nepp= number of ear plant-1 (number), nkpr= number of kernel row1(number), el=ear length (cm) and ed= ear diameter (cm), tkw=thousand kernel weight (g), of the genotypes used. diribu et al. highland adapted double haploid maize inbred mating desig n 131 table 5. grain yield mean and sca effects of highland maize lines evaluated across locations using different tester groups. tester-1 (fs59) tester-2 (fs67) tester-3 (ec573) tester-4 (kitsyn ii) line gy sca gy sca gy sca gy sca l1 8.87 -0.01 6.5 -1.08* 8.33 0.9 8.5 0.19 l2 8.25 0.25 6.7 0.01 6.72 0.19 6.95 -0.45 l3 8.8 -0.71 8.94 0.71 7.34 -0.72 9.65 0.72 l4 8.8 0.24 7.7 0.45 7.65 0.56 6.7 -1.26* l5 9.07 -0.89 8.53 -0.14 9.3 0.79 9.63 0.24 l6 10.94 -0.03 9.77 0.12 8.8 -0.69 10.97 0.6 l7 8.07 -0.01 7.87 1.09* 6.87 0.25 6.15 -1.34** l8 8.5 -0.48 7.53 -0.15 7.1 -0.41 9.45 1.05* l9 11.17 1.54** 7.65 -0.67 7.37 -0.78 8.95 -0.08 l10 7.9 -0.35 7.3 0.34 6.83 0.03 7.65 -0.02 l11 9.17 0.29 7.35 -0.22 7.25 -0.16 8.4 0.1 l12 9.3 0.16 7.37 -0.45 7.7 0.03 8.8 0.25 based on these classifications, the two tester groups could not be suggested as most contrasting candidate testers for assigning the lines into heterotic groups. on the other hand, absence of distinct categories or classifications for the remaining five lines could be attributed, in part, to the limited discriminating power of the testers which restricts the development of good testers for the highland breeding program. therefore, it is imperative to further confirm these results through applications of molecular techniques in addition to multi-environment combining ability tests. because no one method can absolutely be used to estimate heterotic grouping, so that, the integration of different methods can be the best solution since each method has its own limitations as suggested by duvick et al. (2004). 4. conclusions maize breeding relies on the extent of genetic variability available among genotypes. the lines and testers used in the present study were diverse, resulting in the expression of variation among genotypes for various traits. the genetic variability observed among the lines and testers used in this investigation for various traits implied great potential for the development of improved hybrids for the highland agro-ecologies. from the combined analysis, gca accounted for 73.20% while for sca was 26.80% of the total sum of squares for grain yield showing the importance of additive genetic effect over the non-additive. line like l5 and l6 showed highly significant and positive gca effects for gy across locations. in addition, l6 had revealed positive gca effects for other yield related traits such as nepp, nrpe, nkpr and ed. consequently, these lines can selectively be used to make progress in yield improvement in the highland maize breeding program. crosses such as l7xt2, l8xt4 and l9xt1 manifested significant and positive sca effects for grain yield. besides, the significant and desirable sca effects by some of the crosses for increasing grain yield, number of ear per plant, number of rows per ear, number of kernels per row, ear diameter, ear length and thousand kernel weight, reduced days to maturity and plant height indicated the prevalence of dominance gene effects that could be exploited through hybrid breeding method. the two major heterotic groups (ecuador and kitale) used in the highland maize breeding program were able to categorized seven lines (l2, l3, l4, l6, l8, l9, and l12) into the already known heterotic groups. particularly, l3 and l6 were classified into their respective heterotic groups in a similar pattern showing that the restricted power of the testers to discriminate. consequently, the applications of molecular techniques in addition to multi-environment tests are important to confirm further highland maize breeding program. 5. acknowledgements we genuinely thank highland maize breeding programme of ambo plant protection research centre for their material support during the accomplishment of this research. 6. references ahmad, a. and saleem, m. 2003. combining ability analysis in maize. international journal of agriculture and biology 5:239-244. aly, r. s. 2013. relationship between combining ability of grain yield and yield components for some newly yellow maize inbred lines via line x tester analysis alex. j. agric. res. vol. 58, no. 2, pp.115‐124. aly, r. s. and amer, e. a. 2008. combining ability and type of gene action for grain yield and some other traits using line × tester analysis in newly yellow diribu et al. east african journal of sciences volume 13 (2) 121-134 132 maize inbred lines (zea mays l.). journal of agricultural sciences 33: 4993-5003. aly, r. s., metwali, e. m., and mousa, s. t. 2011. combining ability of maize (zea mays l.) inbred lines for grain yield and some agronomic traits using top cross mating design. global journal of molecular science 6(1): 01-08. aminu, d. and izge, a. 2013. gene action and heterosis for yield and yield traits in maize (zea mays l.), under drought conditions in northern guinea and sudan savannas of borno state, nigeria; 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third international scientific symposium "agrosymjahorina 2012" 10.7251/agsy1203205c udk 633.15-152. diribu et al. east african journal of sciences volume 13 (2) 121-134 134 ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2019) volume 13 (2) 169-184 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: minasie2017@gmail.com attribution-noncommercial 4.0 international license. a gis-based multi-criteria land suitability analysis for surface irrigation along the erer watershed, eastern hararghe zone, ethiopia kassaye hussien1*, gezahagn woldu1 and shimelis birhanu2 1 school of geography, department of gis, haramaya university, ethiopia; 2 department of agricultural engineering, haramaya institute of technology, haramaya university, ethiopia abstract: the high dependency on rain-fed and the incessant erratic rainfall during the main growing seasons in ethiopia pose a huge threat to agricultural production and productivity. multi-criteria irrigation land suitability analysis and mapping can play an important role not only in sustainable use of scarce resources, but also in overcoming the global problem of water scarcity and crop production caused due to the high degree of rainfall variability and unreliability. the objective of this study was to determine suitable sites for surface irrigation along the erer watershed of east hararghe zone, ethiopia. the study employed gis-based multi criteria land suitability evaluation method considering fifteen factors , namely, soil ph, soil type, soil drainage, soil depth, awsc, impermeable layer, ece, cec, phase, organic carbon, texture classes, obstacle to root, land use /land cover, slope, and distance from the river outlets to find suitable land for surface irrigation. each factor was standardized to a common measurement scale so that the results represent numeric range giving higher values to more suitable and lower values to less suitable attributes. using the weighted overlay tool, the values of each dataset were weighted and combined to find the most suitable location for irrigation using the arcgis environment. the results of the study revealed that about 386,731ha (11.7% of the watershed area) is highly suitable while 140,308 ha (36.3% of the watershed area) is not suitable for surface irrigation. the remaining suitability classes placed within the marginally and moderately suitable categories were about 151,120 ha (39.07%) and 50,223 ha (12.98%) of the watershed area, respectively. the findings drawn from this study can play an indispensable role in boosting irrigable land and crop production in the study area by considering suitable irrigable lands in terms of the fifteen factors described. keywords: gis; multi criteria evaluation; surface irrigation; weighted overlay analysis; suitability map 1. introduction ethiopia, one of the mountainous countries in east africa, is often called the “water tower of africa” due to its topographical nature and climatic condition. the country is endowed with a substantial amount of water sources. it receives about 980 billion cubic meters square of rain water per year. the irrigation potential is estimated to be about 3.7 million hectares, of which only 190,000 hectares (5.3% of the potential) has currently been under irrigation and plays insignificant roles in the country‟s agricultural production (negash and seleshi, 2004). despite the presence of immense potential for expanding irrigated agriculture in ethiopia, irrigation systems are little developed and at an infant stage in the country, with very low contributions to the growth of the agriculture sector, which is the backbone of the country‟s economy (moa, 2011 and seleshi, 2010). the country largely depends on rain-fed agriculture which is highly vulnerable to high degree of rainfall variability and unreliability (hailemariam et al., 2018). this in turn has resulted in frequent crop failures and droughts which negatively affect the agricultural productivity and food supply of the fast-growing population in the country. the high dependency on rain-fed farming in the dry lands of ethiopia and the erratic rainfall requires an alternative means to improve agricultural production and productivity. these can be achieved through an optimal development of surface irrigation (fao, 2003). surface irrigation is the application of water by gravity flow to the surface of a field either the entire field is flooded (basin irrigation) or the water is fed into small channel (furrow) or strip of land (borders). it is the oldest and still the most widely used method of water application to agricultural lands. surface irrigation offers numerous benefits for the less skilled and poor farmers. even if local irrigators have least knowledge of how to operate and maintain the system, more than 90% of the world uses surface irrigation (saymen, 2005). these systems can be developed at the farm level with a minimal capital investment (kalkhajeh et al., 2012). proper land suitability evaluation of land resources in irrigation command area is a prerequisite for better utilization of land resources which help to optimize and sustain the productivity of these land resources. availability of irrigation leads to land use change as well as intensive cropping system. improper use of irrigation water has resulted in degradation of natural resources that leads to decline in the productivity of land resources and deterioration of land quality for its future use (sulieman et al., 2015). so as to address this water challenge, geographic information system (gis) based multi-criteria land suitability analysis (mclsa) techniques were applied. kassaye et al. east african journal of sciences volume 13 (2) 169-184 170 the techniques can handle large volumes of datasets considering all spatial factors to select surface irrigation site. kumi-boateng et al. (2016) suggested that gis based multi-criteria evaluation land suitability analysis (mcelsa) techniques are possible way of making optimal decisions in selecting suitable land for dam or surface irrigation. gis based multi-criteria evaluation (mce) techniques are the numerical algorithms that define suitability of solution based on input criteria and weights together with some mathematical or logical means of determining tradeoffs when conflicts arise. in this technique, weight can be assigned to the geospatial dataset from various sources to reflect their relative importance (abeyou et al., 2012) and overlaid using gis-based multi-criteria analysis techniques in the arcgis software environment. therefore, this study was aimed at identifying suitable areas on gis-based mce for surface irrigation along the erer watershed of eastern hararghe zone, ethiopia. 2. materials and methods 2.1. description of the study area the study area, erer watershed, is one of the largest watersheds of the shebelle basin in eastern hararghe zone with a total area of 386,731 ha. it lies between 8o 20„n and 9o 20„n latitude and 41o 40„e and 42o 30„e longitude (fig. 1). elevation of the watershed ranges between 886 m and 2,885 m above sea level (fig. 1). in the watershed, there are traditional small-scale irrigations managed by local farmers along the erer river. according to the data collected from ethiopian national meteorological services agency, this region receives 523.4 mm of mean annual precipitation with an average temperature that varies from 10.5°c to 32°c. the river erer with 138.35 km length emanates from an elevation of about 2,885 m in the eastern hararghe highlands (fig. 1). figure1. map of the study area 2.2. methods 2.2.1. data and materials topographic map (1:50,000) and aerial photograph (1:250,000) of the study area were collected from the ethiopian mapping agency (ema). the project area was selected based on topography and access to irrigation water supply. information was collected on climate, soil and vegetation cover of the study area from available documents. interpretation and identification of land features was made using the existing 1:250,000 and 1:50,000 scale aerial photograph and topographical maps, respectively. the watershed and river networks were delineated from digital elevation model (dem) using arc hydro tools extension in arc map environment. the data were then integrated with other data in the arcgis software version 10.3. the dem from the advanced spaceborne thermal emission and reflection radiometer (srtm) was used for topographic analysis. soil data were downloaded from harmonized world soil database (hwsd) website (nachtergaele et al., 2009). these digital datasets were imported and integrated in the arcgis environment. in addition, frequent field observations were carried out to collect the ground truth of land-use/land-cover using hand-held global positioning system (gps). meteorological data were collected from national meteorological agency (nma). landsat 8 operational land imager (oli) image of 2015 and aster dem were downloaded from usgs website. 2.2.2. preparation of database since the primary issue in mce is concerned with how to combine the information from several criteria to kassaye et al. gis based multi-criteria land suitability analysis for surface irrigation 171 form a single index of evaluation, series of base maps and images were prepared to facilitate the processing, data integration and functionality of gis software (eastman, 2001). all preprocessing activities such as downloading, extracting, geo-referencing, formatting and resampling digital data of the factors were done before analysis. first, the main watershed, sub watersheds, river networks, slope and outlets were delineated from dem (30m) using arc hydro tools in gis platform. then, lulc map was generated from landsat8 satellite imagery (kassaye et al., 2018 and fig. 2). finally, twelve soil factors were extracted from harmonized world soil database version 1.2. table 1. spatial database and sources. data type source meteorological data national metrological agency (nma) ground control points (gcp‟s) gcps were collected from each lulc soil data harmonized world soil database version 1.2 topographic map and aerial photograph ethiopian mapping agency (ema) key informant interview experts in the field digital elevation model (dem) aster website landsat8 (oli) usgs portal http://www.earthexplorer.usgs.gov. table 2. software packages and devices. software’s and instruments application arcgis10.3 erdas imagine 2013 elshal smart gis idrisi 32 envi 5.2 google earth digital camera gps(garmin72h) data visualization and map layout image preprocessing and classification download rectified google earth image weighting influencing percentage image correction ground verification collect ground truth collect ground control point (gcp‟s) kassaye et al. east african journal of sciences volume 13 (2) 169-184 172 figure 2.flow chart of suitable land analysis for surface irrigation 2.2.3. factors used to map land suitability for surface irrigation factors that affect the suitability of an area for surface irrigation were identified based on literature and expert opinion (worqlul et al., 2017). fifteen factors were used to assess the suitability of surface irrigation. the factors (sub models) were soil ph, soil type, soil drainage, soil depth, available water storage capacity (awsc), impermeable layer (il), cation exchange capacity (cec), electrical conductivity (ece), phase, organic carbon (oc), texture classes (tc), obstacle to root crops (orc), land use /land cover (lulc), slope (s), and distance from the river outlets (dws) to find suitable land for surface irrigation. dem satellite imagery soil data 1. soil ph 2. soil drainage 3. soil type 4. soil depth 5. awsc 6. impermeable layer 7. ece 8. cec 9. phase 10. organic carbon 11. texture classes 12. obstacle to root lulc fill slope flow direction depression less dem flow accumulation snap pour point delineate watershed establishing the factor weights watershed pour point weighted overlay (mce) euclidean distance from outlets standardizing the factors watershed map majority filter river networks suitable land for irrigation spatial data kassaye et al. gis based multi-criteria land suitability analysis for surface irrigation 173 2.2.3.1. soil soil is a key factor in determining the suitability of an area for agriculture and sustained irrigation (dagnenet, 2013 and usdibr, 2003). its primary influence is on the productive capacity, but it may also influence production and development costs. both the spatial and attribute soil data were obtained from the harmonized world soil database (hwsd) version 1.2. as usdibr (2003) stated that several soil characteristics must be evaluated to determine soil suitability for irrigation. the primary factors are soilmoisture relationships, toxicity, fertility, depth to gravel and cobble, continuing layer, and the erosion hazard. therefore, for this study chemical (ph, organic carbon, awsc, cec, ece) and physical (soil type, soil drainage, soil depth, obstacle to roots of crops, impermeable layer, phase and texture classes) primary soil factors were extracted from hwsd (table 3 and 4 and fig. 3). table 3 and 4 illustrate the detail agronomical significances of each soil factors extracted from hwsd which has been compiled by food and agriculture organization of the united nations (fao), international institute for applied systems analysis (iiasa), isric-world soil information institute of soil science – chinese academy of sciences (isscas) and joint research centre of the european commission (jrc) (nachtergaele et al., 2009). phases are subdivisions of soil units based on characteristics which are significant for the use or management of land. they are used, for example, where indurated layers or hard rock occur at shallow depth (fao, 1995). the soil map of erer watershed contains four phases which are lithic, gravelly, sodic and no phase. as it is stated in hwsd version 1.2, lithic phase is used when continuous coherent and hard rock occurs within 50 cm of the soil surface; the sodic phase marks soils which have more than 6 percent saturation with exchangeable sodium in some horizons within 100 cm of the soil surface. the gravelly phase is used to indicate over 35% gravels with diameter < 7.5 cm (nachtergaele et al., 2009). table 3. agronomic significances of chemical soil factors for land suitability assessment of surface irrigation criteria parameter agronomic significances of the soil source <15 very low available water storage capacity nachtergaele et al., 2009 15 75 low available water storage capacity awsc (mm/m) 75 100 moderately good for most crops > 100 optimum for most crops usdibr, 2003 < 9 very low nutrient storage capacity for most crops nachtergaele et al., 2009 9 12 low nutrient storage capacity for most crops cec (cmol kg-1) 12 13 marginally good nutrient storage capacity for most crops usdibr, 2003 > 13 considered satisfactory nutrient storage capacity for most crops < 0.1 very low salt content ideal for crops nachtergaele et al., 2009 ece (ds m-1) 0.1 1.1 moderate salt content > 1.1 high salt content most crops do not resist <0.7 invariable need organic or inorganic fertilizer nachtergaele et al., 2009 0.7 0.74 poor in organic matter oc (%) 0.74 1.15 marginally good for crops usdibr, 2003 1.15 2.18 moderately good for crops > 2.18 optimum for crops > 4.4 extremely acid soils include acid sulfate soils 4.4 5.4 very acid soils. some crops are tolerant this (tea, pineapple). usdibr, 2003 ph 5.4 6.5 acid to neutral soils: these are the best ph conditions for nutrient availability and suitable for most crops. 6.5 6.6 carbonate rich soils. nachtergaele et al., 2009 > 6.6 indicates alkaline soils often highly sodic (na reaching toxic levels), kassaye et al. east african journal of sciences volume 13 (2) 169-184 174 table 4. significances of physical soil factors for land suitability assessment of surface irrigation. 2.2.3.2. slope slope is the principal topographic characteristic which determines suitability of land for irrigation. it affects the suitability of an area in terms of land preparation for irrigation and irrigation operation (usdibr, 2003). it influences method of irrigation, land development, design of on farm irrigation systems, erosion hazard, drainage requirements, water use practices, crop, and other management and production costs. thus, the study of slope is a principal factor for land suitability study for surface irrigation. the slope of the watershed was extracted from 30 m resolution dem and was classified in to four classes (0 – 2%, 2 – 5%, 5 – 8% and > 8%) based on (fao, 1979) and united state department of the interior bureau of reclamation (usdibr, 2003) technical guidelines for suitability land classification method for surface irrigation. 2.2.3.3. land use land cover land use data help to identify the productivity of an area for irrigation. to generate and analyze the lulc suitability map for surface irrigation, the landsat 8 operational land imager (oli) image was downloaded from usgs website. the land sat imagery was classified in to six major land use classes (bare land, bush land, dispersed forest, farm, range land and settlement). the land use group was classified into four classes ranging from highly suitable (class s1) to not suitable (class s4). table 6 presents the fao framework of land suitability classification. farm land use types were classified as highly suitable (s1) and rangeland, which requires land clearing and leveling, as moderately suitable (s2). bush land which requires higher initial investment for land preparation, were reclassified as marginally suitable (s3). dispersed forest, settlement and bare land use types were reclassified as not suitable (s4). 2.2.3.4. distance from water supply (source) to identify irrigable land close to the water supply (rivers), four (from 0 – 5, 5 10, 10 – 20 and > 20 km2) buffer zone distance were generated from the watershed outlets and was reclassified. (mandal et al., 2017). then reclassified distance map was used for weighted overlay analysis along with other factor maps (table 5). distance from water source is the highest weighted factor which accounts 18% of the influences among the other factors (table 9). this is to reduce cost for redirecting the water to the command area. criteria parameters agronomic significances for surface irrigation source drainage well moderately well imperfectly poor excessive optimum moderate marginal not ideal for upland crops has little significance nachtergaele et al., 2009 sodic optimum nachtergaele et al., 2009 gravelly moderate usdibr, 2003 phase lithic very low no phase no data >150 optimum nachtergaele et al., 2009 impermeable layer (cm) <40 not optimum > 80 optimum obstacle to roots (cm) 40 60 modrate nachtergaele et al., 2009 20 40 low soil depth(cm) < 10 .10 50 50 100 > 100 very low low marginal optimum mandal et al., 2017 soil type chromic luvisols humic nitosols eutric vertisols haplic calcisols rendzic leptosols lithic leptosols optimum moderate marginal low very low very low fao and unesco,1988 texture classes sandy loam loamy sand loam silt loam marginal low optimum moderate usdibr, 2003 mandal et al., 2017 kassaye et al. gis based multi-criteria land suitability analysis for surface irrigation 175 table 5. agronomic significances of other physical factors for land suitability assessment of surface irrigation. criteria parameter agronomic significance source euclidean distance (km) 0 5 5 10 10 20 > 20 optimum moderate marginal low mandal et al, 2017 lulc rangelands farmland dispersed forest settlement bush bare land moderate optimum low not optimal marginal not optimal slope (%) 0 2 optimum mandal et al, 2017 2 5 moderate usdibr, 2003 5 8 marginal buhari, 2014 > 8 low 2.2.4. structure of land suitability classifications land suitability is the fitness of a given type of land for a defined use by food and agricultural organization (fao, 1976). the fao (1976 and 2007) proposed an approach for land suitability evaluation in terms of suitability ratings from highly suitable to not suitable based on the suitability of land characteristics to different crops. according to fao (1976 and 1983), land suitability maps are generally classified into two orders, i.e., suitable(s) and not suitable (n). these orders are further classified in to three and two classes respectively based on their benefits and limitations: highly suitable (s1), moderately suitable (s2), marginally suitable (s3) and temporarily not suitable s4 (n1) and permanently not suitable s5 (n2) respectively (table 6). table 6. framework of land suitability classification. class land description s1 highly suitable land without significant limitations. this land is the best possible and does not reduce productivity or require increased inputs. s2 moderately suitable land that is clearly suitable but has limitations that either reduce productivity or require an increase of inputs to sustain productivity compared with those needed on s1 land. s3 marginally suitable land with limitations so severe that benefits are reduced, and/or the inputs required sustaining production need to be increased so that this cost is only marginally justified. n1 currently not suitable land having limitations which may be surmountable in time, but which cannot be corrected with existing knowledge at currently acceptable cost; the limitations are so severe as to preclude successful sustained use of the land in the given manner. n2 permanently not suitable: land having limitations which appear as severe as to preclude any possibilities of successful sustained use of the land in the given manner. source: fao, 1976 and 1981 2.2.5. derivation of criterion maps deriving datasets is the step after having defined the problem and breaking it into sub models when building a suitability model based on multi criteria evaluation (esri, 1996). selection of evaluation criteria in this study was based on project objective, spatial scale, and, data availability. thus, the study aimed at considering fifteen factors (sub models) , namely, soil ph, soil type, soil drainage, soil depth, awsc, impermeable layer, ece, cec, phase, organic carbon, texture classes, obstacle to root, land use /land cover, slope, and distance from the river outlets to find suitable land for surface irrigation. criterion maps or datasets were derived to each factor in gis environment (fig. 3). soil datasets with the attribute were derived from hwsd (table 3 and 4). land use/ land cover dataset was derived from landsat 8 satellite imagery and slope was derived from dem (fig. 3 and table 5). finally, to find ideal site away from the river, the euclidean (straightline) distance was derived from the river‟s outlet points (fig. 3 and table 5). these attributes were used to create the criterion maps database in arc gis (fig. 3 kassaye et al. east african journal of sciences volume 13 (2) 169-184 176 and table 3, 4 and 5). the criterion maps were standardized to a common numeric range for further processing that was establishing the factor weights (esri, 1996). figure 3. factors maps and level of suitability to assess optimum location for surface irrigation: (a) obstacle to roots of crops, (b) soil depth, (c) phase of the soil, (d) impermeable layer, (e) soil type, (f) soil texture class, (g) drainage (h) slope (i) distance from water sources (j) soil organic carbon (k) available water storage capacity, (l) cation exchange capacity, (m) soil salinity, (n) soil ph and (o) land use land cover. kassaye et al. gis based multi-criteria land suitability analysis for surface irrigation 177 2.2.6. standardizing the factors each of the factors was standardized using the module reclassify so that the results represent a common numeric range giving higher values to more suitable attributes (fig. 3). reclassification is the method to assign values of preference, sensitivity, priority, or some similar criteria to a raster (esri, 2011). as it was quantified in tables 3, 4 and 5, the factors were reclassified as per the spatial existence of the factors in the study area. as a result, of the fifteen factors, impermeable layer has the smallest classes whereas soil type and land use have the largest classes (fig. 3). the reclassification process was done based on the five classes of agricultural land suitability for irrigation according to the fao framework (fao, 1976, 1985; mandal et al., 2017and table 6). 2.2.7. establishing the factor weights this stage was done to establish a set of weights for each of the factors. in this stage, the importance or preference of each criterion relative to the rest of the criteria on suitable land selection was expressed by assigning weights (esri, 2012). this was done based on related review literatures, field observation and on expert judgment to fill out a pairwise comparison matrix from which a set of weights referred to as eigenvectors together with consistency ratios were generated for each of the criteria being considered (chen et al., 2010; gizachew and yihenew, 2015). the available values for the comparison are the member of the set: {9, 7, 5, 3, 1, 1/3, 1/5, 1/7, 1/9}, with 9 representing absolute importance and 1/9 the absolute triviality (saaty, 1980; saaty and vargas 1991 and table 8). then the factor weights were evaluated to undertake the multi-criteria evaluation of suitability for surface irrigation development. table 7. factors for surface irrigation land suitability assessment. factors parameters suitability eigenvector of weights weight (%) drainage well s1 moderately well s2 imperfectly s3 0.0408 4.08 poor s4(n1) excessive s5(n5) phase sodic s1 gravelly s2 0.0345 3.45 lithic s3 no phase s4(n1) impermeable layer (cm) >150 s1 0.1108 11.08 <40 s2 obstacle to roots of crops(cm) > 80 s1 40 60 s2 0.1229 12.29 20 40 s3 soil depth(cm) < 10 s4(n1) 10 50. s3 0.0404 4.04 50 100 s2 > 100 s1 soil type chromic luvisols s1 humic nitosols s2 eutric vertisols s3 0.0322 3.22 haplic calcisols s4(n1) rendzic leptosols s5(n2) lithic leptosols s5(n2) texture classes sandy loam s3 loamy sand s4(n1) 0.059 5.9 loam s1 silt loam s2 available water < 15 s4(n1) kassaye et al. east african journal of sciences volume 13 (2) 169-184 178 storage capacity (mm/m) 15 75 s3 0.0634 6.34 75 100 s2 > 100 s1 cation exchange capacity (cmol kg-1) < 9 s4(n1) 9 12. s3 0.0744 7.44 12 13. s2 > 13 s1 electrical conductivity of soil (ds m-1) < 0.1 s1 0.1 1.1 s2 0.0351 3.51 > 1.1 s3 < 0.7 s5(n2) 0.7 0.74 s4(n1) organic carbon (%) 0.74 1.15 s3 0.0388 3.88 1.15 2.18 s2 > 2.18 s1 < 4.4 s5(n2) 4.4 5.4 s3 ph 5.4 6.5 s1 0.0292 2.92 6.5 6.6 s2 > 6.5 s4(n1) euclidean distance(km) 0 5 s1 5 -10. s2 0.18 18 10 20. s3 > 20 s4(n1) lulc rangelands s2 farmland s1 dispersed forest s4(n1) 0.0369 3.69 settlement s5(n2) bush s3 bareland s4(n1) slope (%) 0 2 s1 2 5. s2 0.1017 10.17 5 8. s3 > 8 s4(n1) after the pairwise comparison matrices were filled, the weight module of idrisi software was used to identify inconsistencies and develop the best fit weights (table 9). the technique described here and implemented in the idrisi software was that of pairwise comparisons developed by saaty (1977) in the context of a decisionmaking process known as the analytical hierarchy process (ahp). table 8. scale for pair-wise comparisons (saaty and vargas, 1991). intensity of importance description 1 equal importance 3 moderate importance 5 strong importance 7 very strong importance 9 extreme importance 2,4,6,8 intermediate values reciprocals values for inverse comparison kassaye et al. gis based multi-criteria land suitability analysis for surface irrigation 179 2.2.8. undertaking the multi-criteria evaluation once the weights were established, the module weighted overlay tool (for multi-criteria evaluation) was used to combine the factors for undertaking multi criteria evaluation (fig. 4). with a weighted linear combination, factors are combined by applying a weight to each followed by a summation of the results to yield a suitability map i.e.: s = wixi where s = suitability; wi = weight of factor i; xi = criterion score of factors i the procedure is optimized for speed and has the effect of multiplying each factor by its weight, adding the results, and then successively multiplying the result by each of the factors. the eigenvectors weights and weights sum (the total influence for all factors) to 1 and 100 percent, respectively (table 9). gis and mce techniques are globally recognized for its outstanding support in map overlay process for any form of land suitability analysis (carver, 1991 and malczewski, 1999). the primary issue in mce is concerned with how to combine the information from several criteria to form a single index of evaluation (eastman, 2001). prioritization and selection of criteria„s influence was executed by reviewing important literatures related to this study and supplemented by opinion of experts in the field and other stake holders based on their preliminary knowledge and fair judgment (eastman, 2006). the basic advantages of using mce techniques are related to possibilities to evaluate all factors at different scales. moreover, it enables the researchers to merge information gathered from different criteria based on their relative weights guided by experts‟ knowledge to produce single out put map (ebistu et al., 2013; malczewski, 2004 and 2006) and (fig. 4). finally, majority filter tool was used to refine optimal areas for surface irrigation (esri, 2008). 4. results and discussion 4.1. effect of factors for surface irrigation suitability mapping the result of the pair-wise comparison matrix showed that fifteen of the major factors were compared one-toone and scored using a saaty scale (saaty, 1977). the eigenvector was calculated as the product of the row matrix and the weights of each factor were calculated by normalizing the respective eigenvector weight (ew) by the cumulative vector. table 9 shows the weights of importance or preference of each criterion relative to rest of the criteria on suitable land selection. as a result, physical factors such as distance from water source (dws), obstacle to roots of crops (orc), impermeable layer (il), lithic phase and slope(s) were the most important factors for determining the suitability of the watershed for irrigation followed by cat-ion exchange capacity (cec), available water storage capacity (awsc) and texture classes(tc), soil drainage(dr) and soil depth(sd); with 7.44%, 6.34% and 5%, 4.1% and 4.04%, of weight of influence respectively. land use land cover (lulc), electrical conductivity (ec), organic carbon (oc), ph, and soil type were listed as less important, with 3.69, 3.51%, 3.88% 2.92% and 3.22% weight of influence respectively (table 9). table 9 presents the results of the pair-wise comparison matrix and influences of weights of factors. kassaye et al. east african journal of sciences volume 13 (2) 169-184 180 table 9. pairwise comparison matrix for assessing the comparative importance of fifteen factors awsc cec dr ec dws phase il lulc oc orc ph s sd st tc ew w (%) awsc cec dr ec dws phase il lulc oc orc ph s sd st tc 1 1 1/2 1/2 2 1/2 2 1/2 1/2 2 1/4 2 1 1/2 1 1 1 2 1/2 2 1 2 2 1/2 5 1 1 1 1 1/5 1/2 1/3 1/4 1/5 1/7 1/2 1/3 1/5 1/5 1 2 1 2 5 1/2 2 1 1 1/3 1 1/5 1/4 2 1/4 1 1/2 1/2 1/5 1 3 1 2 1 1 2 1 1/5 1 1/2 1/3 1/3 1 1/3 1/4 1/3 1 2 3 1 2 0.0634 0.0744 0.0408 0.0351 0.18 0.0345 0.1108 0.0369 0.0388 0.1229 0.0292 0.1017 0.0404 0.0322 0.059 1.0001 6.34 7.44 4.08 3.51 18 3.45 11.08 3.69 3.88 12.29 2.92 10.17 4.04 3.22 5.9 100 1 1/3 1/3 3 1 3 1/3 1/5 5 1/4 2 1/2 1/3 1 1 3 1 2 1 1 3 1/2 2 2 1 3 1 2 2 1/2 2 1 1/2 2 1 2 2 1/4 2 1 consistency ratio = 0.07 consistency is acceptable. kassaye et al. gis based multi-criteria land suitability analysis for surface irrigation 181 the credibility of the pairwise matrix consistency was evaluated using consistency ratio. the result was found to be trustworthy with a consistency ratio of 0.07 (eastman, 2006 and worqlul et al., 2017). 4.2. land suitability analysis land suitability analysis for surface irrigation at a catchment scale is an interdisciplinary approach by including the information from various sources such as climate, topography, soils, lulc and distance form water source (bojorquez et al., 2001). potentially surface irrigable land was identified based on the specified suitable criteria by creating irrigation suitability model analysis which involved weighting of values of all the fifteen sub models (factors dataset). the weighted criterions (table 9) were aggregated to produce a final suitability map according to defined regulation in arcgis (fig. 4). the resultant map showed the extent of distribution of the land suitability classes (fig. 3 and table 10). to this effect, out of the total area of the watershed which is 386,731 ha, a small portion of about 45,080 ha (11.7%) of the watershed was assessed highly suitable for surface irrigation due to factors such as gentle slope (0–2%), absence of obstacle to root up to 80 cm depth, absence of impermeable layer within 150 cm soil depth, soil depth greater than 100 cm, closest distance to water sources(0–10 km2) and nonlithic phase (fig. 3). the second portion of 50,223ha (12.98%),) of the total area of the watershed was calculated as moderately suitable land for surface irrigation due to moderate slope (2–5%), moderate cation exchange capacity (12–13 cmol km-1) and gravelly soil texture (fig. 3). the largest part of the watershed 151,120ha (39.07%) of the total area was evaluated as marginally suitable because of factors such as acidic soil ph, low organic carbon content of the soil, low available water storage capacity of the soil and long distance from water sources (10–20 km). the marginally suitable land is in the western and south western part of the watershed. lastly, the second largest part 140,308 ha (36.3%) of the total area of the watershed was found to be unsuitable land for surface irrigation due to physical constraints such as steep slope (> 8%), stoniness, presence of impermeable layer with in 40cm depth, longest distance from water source (> 20km ) in the northern part, shallow soil depth, very low cat-ion exchange capacity(< 9km-1) and presence of obstacle to roots of crops from 20 – 40 cm depth (fig. 3). as seen from the map in figure 4, the largest part of unsuitable land is in the northern and south west central part of the watershed. although the south west central part of the watershed is located close to the water source and has ideal available water storage capacity, it is unsuitable for surface irrigation due to its steep slope (> 8%), shallow soil depth (10 – 50 cm), imperfectly soil drainage and lithic phase (fig. 3 and 4). while the northern part of the watershed has ideal soil depth, soil type, soil texture, soil salinity and available water storage capacity, it was found to be unsuitable land for surface irrigation because of the figure 4. surface irrigation suitability map physical limitations such as very high steep slope (> 8%), high distance from water sources (> 20 km), lithic phase, presence of impermeable layer (20 – 40 cm) and obstacle to root with in 40cm depth (fig. 3). almost the entire study area, caso4 (gypsum and caco3 (lime) were not considered as limiting factors. this is because the content of both caso4 and caco3 uniformly distributed with values from none to very low (0 – 0.1%) and from none to moderate (0 – 9%) respectively. this is consistent the findings of nachtergaele et al. (2009) who reported that up to 2 percent gypsum in the soil favors plant growth, between 2 and 25 percent has little or no adverse effect if in powdery form, but more than 25 percent can cause substantial reduction in yields. the authors added that low levels of calcium carbonate (caco3) enhances soil structure and are generally beneficial for crop production but at higher concentrations they may induce iron deficiency and when cemented limit the water storage capacity of soils. thus, the content of both caso4 and caco3 is ideal for most crops in the study area. in agreement with albaji et al. (2009) and abraham et al. (2013) the overall result showed that physical factors highly determined the suitability of the study area for surface irrigation. albaji et al. (2009) reported that the most limiting factors for surface irrigation were physical parameters such as slope, stoniness and soil depth. corroborating this suggestion, abraham et al. (2013) stated that high slope; gravelly soil texture and shallow soil depth were limiting factors of land suitability evaluation for irrigation in their study area. kassaye et al. east african journal of sciences volume 13 (2) 169-184 182 furthermore, the total area of the existing irrigation is about 4720.14 ha from which, 1506 ha, 1262.14 ha and 1952 ha were found to be moderately suitable, marginally suitable, and unsuitable land classes, respectively. none the existing irrigation land was found to be suitable land classes. table 10. the distribution of land suitability classes in the study area. suitability area(ha) percent not suitable marginally suitable moderately suitable highly suitable 140,308 151,120 50,223 45,080 36.3 39.07 12.98 11.7 total 386,731 100.5 5. conclusion the study has demonstrated that gis techniques are an essential tool for the surface irrigation site suitability evaluation. fifteen factors were used to assess the land suitability site for surface irrigation. the result of pairwise comparison matrix showed that fifteen of the major factors were compared one-to-one and scored using a scale from saaty (1977). the most important limiting factors were distance from water source, obstacle to roots of crops, presence of impermeable layer, slope, and cation exchange capacity with weight of influence of 18%, 12.29%, 11.08%, 10.17% and 7.44% respectively. the study has demarcated areas and produced potential land suitability map of the watershed that will allow growing the right crops at the right site for optimum yield and optimum return to investment for each crop. the result showed that out of the total area of the watershed (386,731ha), 36.3%, 39.07%, 12.98% and 11% were found to be not suitable, marginally suitable, moderately suitable and highly suitable respectively. furthermore, the result of surface irrigation assessment for land suitability showed that the total area of the existing irrigation is about 4720.14 ha from which, 1506 ha, 1262.14 ha and 1952 ha were found to be moderately suitable, marginally suitable and unsuitable land classes respectively. the existing irrigation land is not suitable for irrigation in general and for surface irrigation in particular based on the factors which were discussed in this study. suitability for growing crop is limited not only by the selected edaphic constraints but also by socioeconomic factors which should be considered for further studies. further research should be conducted to calculate the crop water requirement of the irrigable land of the study area. 6. acknowledgements the authors thank haramaya university for funding this research through staff research grant code: hurg2016-01-03. we also thank geographic information science department of the university for providing geographic information science laboratory for accessing computer and internet connection. 7. references abeyou, w., collick, a., rossitor, d. and steenhuis, t. 2012. irrigation area 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classification. technical service center land suitability and water quality group denver, colorado. worqlul, a.w., jeong, j., dile, t. y., osorio, j., schmitter, p., gerik, t., srinivasan, r. and clark, n. 2017. assessing potential land suitable for surface irrigation using groundwater in ethiopia. journal of applied geography, 85: 1-13. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2019) volume 13 (2) 159-168 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: fikrepatil@gmail.com attribution-noncommercial 4.0 international license. response of garlic (allium sativum l.) growth and bulb yield to application of vermicompost and mineral nitrogen fertilizers in haramaya district, eastern ethiopia fikru tamiru 1 and fikreyohannes gedamu2* 1college of agriculture and natural resource management, dilla university, p. o. box 419, dilla, ethiopia 2college of agriculture and environmental sciences, haramaya university, p. o. box 138, dire dawa, ethiopia abstract: yield of garlic is often constrained by low and unbalanced nutrient supply in the soil. this study was conducted to assess the effect of application of vermicompost (vc) and mineral nitrogen (n) fertilizer on growth and bulb yield of a garlic variety named ‘chelenko i’ the experiment was conducted during the 2016 main rainy season. the experiment was laid out as a randomized block designed in a factorial arrangement and replicated three times per treatment. the treatments consisted of four rates of vermicompost (vc) (0, 2.5, 5.0 and 7.5 t ha-1), and five rates of mineral nitrogen (n) fertilizer (0, 52.5, 80, 105 and 130 kg n ha-1. data were collected on days to maturity, plant height, leaf number, yield components, namely, bulb length and clove weight, and marketable and unmarketable bulb yield of garlic. the data were analyzed and computed using sas software version 9.0 and the means were separated by using turkey’s test at 0.05 probably level . the results revealed significant (p < 0.05) differences in early maturity (130.48 days) at control treatment (zero fertilizers) while late maturity (135.50 days) was at application of 7.5 t ha-1 of vc. significantly (p < 0.05) maximum plant height (60.65 cm), clove weight (2.71 g/clove), and marketable bulb yield (12.32 t ha-1) were recorded at the rate of 7.5 t ha-1 of vc. due to combined application of vc (7.5 t ha-1) and mineral n fertilizer (130 kg ha-1) unmarketable bulb yield was reduced by 41.03% over the control treatment. the highest net benefit was recorded from the maximum marketable bulb yield of garlic at the application of 7.5 t ha-1 of vc and 130 kg n ha-1 . thus, it is concluded that combined application of vermicompost and mineral nitrogen fertilizer resulted in optimum production of the crop in the study area. keywords: chelenko i; marginal return; marketable bulb yield; net benefit; vermicompost. 1. introduction garlic is an important vegetable crop in the world and in ethiopia. the productivity of the crop in the world is? in ethiopia, the acreage of garlic cultivation increased from 11,845.53 ha in 2015/16 to 15,381 ha in 2016/17 with a total production of about 107,743.5 and 138,664.3 tones of bulbs with the productivity of 9.10 and 9.02 t ha-1, respectively (csa, 2017). in oromia region, the crop covered 6,430 ha of land with total production of 60,175.5 t and productivity of 9.4 tha-1 in 2016/17. though acreage of garlic, production and productivity are not indicated for eastern hararghe zone, about 50,683 farmers produced garlic in the area (csa, 2017). the yield of recently released garlic variety, chelenko i, is 9.3 t ha-1 on research field was appreciated and selected for eastern and western hararghe zones (tewdros et al., 2014).the product ivity of the crop could be increased to 13 t ha-1.the yield differences exhibited is related to technological resources and the management of the crop rather than to differences in genetic background and performance of the cultivars used (diriba, 2016). optimum application of fertilizers to garlic crop is important for improving growth, yield and marketable bulb proportions as well as bulb quality (diriba et al., 2013). mineral fertilizers of balanced doses increased leaf area, photosynthetic productivity, yield of garlic plant in particular, and resulted in substantial increases in production in general (zhou et al., 2005). however, the crop nutrient requirements vary with species, variety, soil type and season. a blanket recommendation rates of 105 kg n ha-1 and 92 kg p2o5 ha-1 are being used for production of garlic variety ‘tseday’production in many areas (earo, 2004). this is also used for ‘chelenko i‘ (tewdros et al., 2014) as a blanket recommendation. it means that there is no recommendation of optimum rats of fertilizer application for producing the crop in the study area. in general, fertilizers are applied based on blanket recommendations in the country without considering soil fertility levels of specific areas leading to uneconomic fertilizer application (melaku et al., 2017). this is one of the gaps to be bridged through conducting fertilizer trials. additionally, continuous uses of chemical fertilizers also affect the environment through poisoning and exterminating soil microflora and microfauna, thereby adversely changing the chemical and physical properties of soil (pratap et al., 2011). therefore; organic inputs are often proposed as alternatives to mineral fertilizers. due to lack of enough organic material, recently combined application is being appreciated. verma et al. (2013) reported that combined application of organic and inorganic fertilizers provided plants with all essential elements required for growth and mailto:fikrepatil@gmail.com fikru and fikreyohannes east african journal of sciences volume 13 (2) 159-168 160 development. combined application of 50 kg n ha-1 and 10 t manure ha-1 increased total bulb yield of garlic crops (tadila, 2011). therefore, farmers should use integrated organic and inorganic inputs (palm et al., 1997). however, the traditional organic inputs such as crop residues, and animal manures cannot meet crop nutrient demand over large areas because of requiring higher amount, the low nutrient content of the materials, and the high labor demands for processing and application (pratap et al., 2011). the vc helps in reducing c: n ratio, increased humic acid content and provide nutrient in the readily available form to the plants such as nitrate, exchangeable phosphorus, soluble potassium, calcium and magnesium (talashilkar et al., 1999). besides, alemu et al. (2016) reported that increased levels of vc from 0 to 5 t ha-1 increased soil fertility with increased economic return. integrated nutrient supply approach is one of the opportunities for obtaining fairly high productivity with substantial fertilizer leading to sustainable agriculture (bhagwan et al., 2012). therefore, combination of vc and mineral n fertilizer is crucial to increase productivity of plants with reduced pollution of environment. enhancing garlic productivity in eastern hararghe zone is an important objective of research on crops. however, no significant improvement in yield has been recorded so far. farmers in haramaya district produce local varieties of garlic crop in homesteads. the garlic variety chelenko i was developed and newly released by haramaya university in 2013 (tewdros et al., 2014). varieties may also differ in their response to source and rate of applied fertilizers (zhou et al., 2005). so far, no research has been conducted to elucidate the effect of applying mineral nitrogen and vc on the performance of garlic in the area. it is imperative to conduct research on vermicompost and inorganic nitrogen fertilization to increase productivity with recently released variety of garlic. therefore, the study was initiated to evaluate the effect of vermicompost and mineral nitrogen fertilizer rates on garlic productivity and production. 2. materials and methods 2.1. description of the study area the experiment was conducted at haramaya university main campus, rare research field in 2016 main cropping season (august-december). the experimental site is geographically located in eastern part of ethiopia, which is located at the distance of about 25 km in the north-easterly direction from the town of harar, at altitude of 2006 meters above sea level, latitude of 9°24''n latitude, and longitude of 42°03''e. the site has a bimodal rainfall distribution pattern and is representative of a sub-humid, mid-altitude agroclimatic zone. the soil of the experimental site is sandy loam in texture (simret et al., 2014). 2.2. experimental materials and design garlic variety ‘chelenko i’ was used which was released in 2014 for mid to high altitude garlic growing areas of eastern and western hararghe zones by haramaya university. it takes about 132 days to mature with productivity of 9.3 t ha-1(tewodros et al., 2014). the treatments consisted of four rates of vc (0, 2.5, 5.0 and 7.5 t ha-1), and five nitrogen fertilizer rates (0, 52.5, 80, 105 and 130 kg n ha-1) total of 20 treatments. the experiment was laid out as a randomized complete block design in a factorial arrangement and replicated three times per treatment. 2.3.experimental procedures and crop management experimental field was ploughed by a tractor. the plots were leveled and ridges at 20 cm high were prepared. the gross plot size was 2.0 m x 1.5 m (3.0 m2). spacing between blocks and plots were 0.75 m and 0.5 m, respectively. vc was applied two weeks before planting to randomly assigned treatments to each plot and worked into the soil. one-fourth, half and the remaining one-fourth of the n fertilizer as per the treatment was applied at planting, three weeks and six weeks after emergence of the garlic plants, respectively. to all of the plots, phosphorus (92 kg p2o5 ha-1) was applied at planting through triple superphosphate (tsp). healthy and uniform medium-sized cloves of 1.5-2.50 g (fikreyohannes et al., 2008), were selected and planted on 11 august 2016 at the depth of 3-4 cm. the cloves were planted on the ridge at the spacing of 30 cm between rows and 10 cm between plants. thus, there were five rows in each plot and 20 plants in a row. the outer most one row on each side of a plot and 20 cm on both ends of each row were considered as border rows. thus, the net plot size was 0.9 m x 1.8 m (1.62 m2). the treatments were harvested on 16 december 2016, when 70% of the plants senesced and showed neck fall in the plots (getachew and asfaw, 2000; earo, 2004). 2.4. vermicompost and soil sample analysis vermicompost, which was made from lantana camara, partinium hystrophorous and farmyard manure, was analyzed before applying to the soil. composite samples were taken and broken into small crumbs and prepared for determining chemical properties. the sample was air-dried and sieved through a 2mm sieve. the ph value of vermicompost was determined from the filtered suspension of 1:2.5 soils to water ratio using a glass electrode attached to a digital ec meter and ph meter (jones, 2003). the sample was analyzed for electric conductivity (ec), total n, available p, exchangeable k, organic matter and organic carbon. total n was determined using the kjeldhal method (jackson, 1958). available p was determined by extraction with 0.5 m sodium bicarbonate (nahco3) according to the methods of olsen et al. (1954). exchangeable potassium was determined with a flame fikru and fikreyohannes response of garlic vermicompost and mineral nitrogen fertilizers 161 photometer after extraction with 0.5 ammoniumacetate according to hesse (1971). organic carbon of the soil was determined by the walkley-black method (1934). the soil samples were taken randomly using an auger in a zigzag pattern from the entire experimental site before planting. ten soil samples were taken from the top soil layer to a depth of 20 cm and composited in a bucket to represent the site. the soil was broken into small crumbs and thoroughly mixed. from this mixture, a composite sample weighing 1 kg was filled into a plastic bag. the chemical content of the soil was determined using similar procedures used for the vc as it was developed for the soil. soil texture was determined by bouyocous hydrometer method (moodie et al., 1954). 2.5. data collection and measurement data were collected on growth parameters, namely, plant height, number of leaves per plant, days to 90% physiological maturity, and yield components, bulb length, clove weight, and marketable and unmarketable bulb yield and measured timely as per the recommendation to produce the crop (earo, 2004). plant height (cm): height of 10 randomly selected and pre tagged plants from the net area in each plot was measured from the soil surface to the tip of the plant using ruler and their average was expressed as plant height per plant. number of leaves (plant-1): the number of leaves of the above pre tagged plants was counted and their average was taken and expressed as number of leaves per plant. days to 90% physiological maturity: it was recorded as the number of days required from planting to the time when 90% of the plants in each plot show senescence of leaves. bulb length (cm): the length of 10 bulbs that was used for bulb diameter was measured from the base of the bulb to the point where neck of the bulb begins with vernier caliper. clove weight (g): the weight of all the counted above cloves was taken and the average was expressed as clove weight. marketable bulb yield (t ha-1): bulbs harvested at 90% physiological maturity of the plants from the net plot area and were cured for 10 days under ambient condition by thinly spreading. the bulbs then in a plot free from diseases, damages or blemishes and greater than 1 g cloves sized bulb (fikreyohannes et al., 2008) were recorded and converted into t ha-1. unmarketable bulb yield (t ha-1): the bulbs which were diseased damaged or blemished and bulb size of less than 1 g cloves were recorded as unmarketable bulb and expressed as unmarketable bulb yield. 2.6. data analysis collected data were subjected to analysis of variance (anova) using sas software version 9.0 and the means were separated by using turkey’s method at 0.05 probably level of significant. 2.7. partial economic analysis the partial budget analysis as described by cimmyt (1988) was done to determine the economic feasibility of the garlic production using the prevailing market prices for inputs at planting and for the outputs at the time of crop harvest. it was calculated by taking into account the additional input and labor cost involved due to additional input and the gross benefits obtained from garlic production. average yield was adjusted downward by 10% to reflect the difference between the experimental yield and farmers’yield could obtain under their management practices as described by cimmyt (1988). the field price of garlic was calculated as (sale price minus the costs of harvesting, cleaning, bagging and transportation). the net benefit was calculated as the difference between the gross field benefit in ethiopian birr per hectare (etb ha-1) and the total variable costs (etb ha-1) . marginal rate of return (mrr %) was calculated by dividing change in net benefit or gross benefit by change in cost which was the measure of increasing in return by increasing input. this means by subtracting gross benefit at control treatment from gross benefit of each treatment and divide by total variable cost of each treatment and multiplying each value by 100%. 3. results and discussion 3.1. soil sample analysis and vermicompost 3.1.1. physical and chemical properties of soil of the experimental site the result of laboratory analysis of selected physical and chemical properties of soils of the experimental area is presented in table 1. the textural class of the soil was sandy clay loam based on the soil textural triangle of the international society of soil science system (moodie et al., 1954; rowell, 1994). the ph of the experimental soil was 7.4 which is moderately alkaline on the basis of ph limit (7.4 to 7.8) as described by jones (2003). the ph is in the range of 6.5 to 7.5, which is favorable for garlic production. the organic matter (om) content of the experimental soil is 2.55%. according to the rating of tekalign (1991), om ranging from 0.86 to 2.59 is low. hence, the soil of the experimental site is low. as per the rating (0.12 to 0.25%) described by berhanu (1980), the total n content of the soil (0.18%) is medium. this value showed that the crop might fikru and fikreyohannes east african journal of sciences volume 13 (2) 159-168 162 respond to the applied vc and mineral n fertilizers (table 1) due to increased soil fertility with application of both fertilizers. the cation exchange capacity (cec) of the experimental soil was 18.61 (cmol (+) kg-1). this value is medium according to the rating (15 to 25) suggested by landon (1991). this indicated that the soil of the experimental site might respond to the different vc and mineral n fertilizer. in accordance with hazelton and murphy (2007) category, the exchangeable soil potassium content of the experimental soil is in medium category. this indicates external application of mineral and/ organic fertilizers containing potassium is important for enhancing the fertility of the crop and yield of the crop 3.1.2. analysis of vermicompost it is crucial to analysis nutrient contents of vc as it is soil activator, soil conditioner, and soil fertility booster with all be required plant nutrient, vitamins, enzymes, growth hormones and beneficial microorganisms (anonymous, 2006). the analysis of vc indicated that the total nitrogen content, exchangeable k, and oc as per hazelton and murphy (2007) were found very high (table 2). according to tekalign (1991) and landon (1991) reports, the om and ec of vc also recorded very high, respectively. the available p is moderate as rating indicated by hazelton and murphy (2007) and the ph neutral (jones, 2003). vc contains 5 times high n and 7 times higher k and 1.5 time than the first 15 cm top soil (parkin and berry, 1994). according to khan and ishaq (2011), the exchangeable potassium content of vc is 58 times higher compared to garden soil. the application of vc increased growth and yield of many horticultural crops (najar and khan, 2013). the high ec, oc, om, nitrogen percent, and exchangeable k and moderate available p, contents of the vc used in garlic production largely contributed to better garlic growth and bulb yield. the application of higher doses of vc resulted in a significantly higher plant growth, yield components and yield compared to the application of lower doses (table 3, 4, 5 and 6) table 1. textural class and chemical properties of the soil of the experimental site at haramaya, eastern ethiopia. soil property value rating reference sand (%) 61 clay (%) 23 silt (%) 16 textural class sandy clay loam moodie et al. (1954) and rowell (1994) ph 1: 2.5 (h2o) 7.4 moderately alkaline jones (2003) oc 1.48 moderate hazelton and murphy (2007) om (%) 2.55 low tekalign (1991) total n (%) 0.18 medium or moderate berhanu (1980) and hazelton and murphy (2007) available p (mg kg-1) 5.58 low hazelton and murphy (2007) exch. k (cmolc kg-1) 0.32 medium hazelto and murphy (2007) cec (cmol (+) kg-1) 18.61 medium landon (1991) note: oc, organic carbon; om, organic matter; ec, electric conductivity table 2. chemical properties of vermicompost. vc chemical properties total n (%) available p (ppm) exchangeable k [c mol(+)/kg] om (%) oc (%) ph ec (msm-1) value 0.56 25.82 23.69 15.39 8.92 7.25 8.83 rating very high moderate very high very high very high neutral very high note: oc, organic carbon; om, organic matter; vc, vermicompost; ppm, parts per million; ec, electric conductivity (hazelton and murphy, 2007). 3.2. vegetative growth and phenological response to fertilizers application on garlic 3.2.1. plant height the analysis of variance showed that main effect of vc and n showed significant differences (p < 0.05) in plant height. however, the interaction of vc and nitrogen rate did not show any significant differences. as compared to control, plant height was increased by 13.22% with the application rate of 7.5 t vc ha-1. this increase in plant growth might be due to the effect of auxins and nutrients which are exerted by bio-enriched (gomaa, 1995). moreover, it could be attributed to the fact that vc contains a good range of additional essential micronutrient other than npk fertilizers, required for healthy plant growth (surindra, 2009). plots which received 105 kg n ha-1 gave optimum plant height. increased level of n from 0 to 105 kg ha-1, increased plant height by 8.89% (table 3). increasing plant growth by increasing n level might be due to its role in photosynthesis, protein synthesis, cell division and enlargement which are the basal steps of plant fikru and fikreyohannes response of garlic to vermicompost and mineral nitrogen fertilizers 163 growth. in addition, n plays an important role in the enzyme activity which reflects more products needed in plant growth (hassan, 2015). nitrogen is a constituent of many fundamental cell components and plays a vital role in all living tissues of the plant. therefore, it has such an effect on promoting vigorous plant growth. kakar et al. (2002) reported that n accounts for a higher percentage of the variation in plant height when it was increased from 50 to 200 kg ha-1. hore et al. (2014) also reported that plant height increased from 53.98 cm to 69.14 cm with increasing level of n from 50 kg ha-1 to 200 kg ha-1. 3.2.2. leaf number according to the analysis of variance for leaf number revealed that the main factor of n and vc, and its interaction showed significant (p < 0.05) influences on leaf number. the highest number leaves per plant were recorded at the combined application of maximum rate of vc and mineral n rates (table 4). application of 7.5 t vc ha-1 in combination with 130 kg n ha-1 increased leaf number by 64.56% over the control plots. the combined application of vc with chemical fertilizer increased the availability of essential soil micronutrients which ultimately promotes the plant growth. the use of organic manure is more beneficial when combined with inorganic fertilizers (mugwira and murwira, 1998). in agreement with present study, mozumder et al. (2007) obtained significant and maximum number of garlic leaves with a fertilizer combination. 3.2.3. days to maturity the main effects of vc and mineral n fertilizer significantly (p < 0.05) influenced days to maturity. however, the interaction effect of vc and mineral n fertilizer application did not significantly influence days to maturity (table 3). in response to increasing the rates of both vc and mineral n fertilizer application, the number of days required for garlic maturity was increased. as vc is suitable for plant growth due to its content of balanced nutrient and plant growth hormone, it prolongs senescence of plants (pashanasi et al., 1996). plots that received vc at the rates of 7.5 t ha-1 matured in 135.53 days which was significantly longest duration with nil, 2.5 and 5 t vc ha-1 application rate as indicated in table 3. prolonged maturity in response to increasing rate of vc may be ascribed to the availability of optimum nutrients contained in vc that may have led to prolonged maturity through enhanced leaf growth and photosynthetic activities thereby increasing partition of assimilate to the storage organ. in agreement with this result, alemu et al. (2016) reported prolonged maturity days of garlic at the rate of 5 t vc ha-1 application. anonymous (2009); and agarwal (1999) showed that vc contains significant amounts of micro-nutrients elements such as copper, zinc, iron and manganese. this content helps the plant to complete their life cycle without nutrient stress that hastens their senescence. increasing mineral n fertilizer level significantly increased days to maturity. average days to maturity was delayed by 4.66 days when 130 kg n ha-1 was applied compared with the control, but the result was in statistical parity with the application of 105 kg n ha-1 (table 3). delay in days to maturity with high levels of n could be attributed to delayed senescence of the canopy of the crop (garlic) and extended physiological activity and continued in photosynthesis. nitrogen, being the major constituent of protein, component of protoplasm and cell wall of the cell, might have imparted favorable effect on the chlorophyll content of leaves. that in turn might have led to increased synthesis of photosynthates, which may have been further utilized for increasing cell growth, resulting in prolonged maturity of garlic. significantly early matured bulb was obtained from the nil nitrogen fertilizer. inadequate n can hasten maturity and limit yield (batal et al., 1994). this result is in agreement with the findings of abreham and essubalew (2015) who reported maturity was delayed by 13 days when 150 kg n ha-1compared with the control, but the value was in statistical parity with the one obtained in response to the application of 100 kg n ha-1. shawol (2010) and tesfaye et al. (2007) also reported that as high rate of n increased days to maturity in onion. islam et al. (2010) noted that plants grown with the highest rate of n took the longest period to complete the vegetative growth. table 3. main of effects of vermicompost and nitrogen in days to plant height and maturity on garlic. factor treatme nt plant height (cm) days to maturity (days) vc (t ha-1) 0 53.57c 130.48c 2.5 56.71b 132.66b 5 57.64b 133.46b 7.5 60.65a 135.53a lsd (0.05) 1.67 0.99 n (kg ha-1) 0 53.57c 130.50d 52.5 53.57c 131.83c 80 57.80b 133.66b 105 58.33ab 134.41ab 130 60.20a 135.16a lsd (0.05) 1.99 1.19 cv % 3.00 0.77 note: means followed by the same letter within a column are not significantly different at 5% level of significance. 3.3. yield components response to fertilizers application on garlic 3.3.1. bulb length the main effects of vc and n fertilizers showed significant (p < 0.05) differences in garlic bulb length, fikru and fikreyohannes east african journal of sciences volume 13 (2) 149-158 164 while their interaction was not showed significant differences in bulb length. table 4. interaction effect of vermicompost and nitrogen on leaf number of garlic grown in haramaya district during the 20, main growing season. treatment leaf number (no.) nitrogen (kg ha-1) vermicompost (t ha-1) 0 2.5 5 7.5 0 8.10i 8.64hi 8.96efghi 9.18defghi 52.5 8.39hi 8.73ghi 9.02defghi 9.62cdefgh 80 8.69fghi 9.78cdefgh 9.94cdefg 10.22cde 105 8.74fghi 10.05cdef 10.38bcd 11.64b 130 9.07defghi 10.22cde 10.60bc 13.33a lsd (0.05) 1.40 cv% 4.67 note: means followed by the same letter within the table are not significantly different at 5% level of significance. as result indicated in table 5, significantly optimum bulb length was recorded with application 7.5 t vc ha-1. significantly lowest bulb length of garlic was obtained from plots that received no vc. there was a significant increase in bulb length of garlic as the rate increased from nil to maximum vc application. the increase is consistent with the postulation that vermicompost is soil activator, soil conditioner, and soil fertility booster with all required plant nutrient, vitamins, enzymes, growth hormones and beneficial micro organisms (anonymous, 2006). pramanik et al. (2007) reported that humic acids released from vc enhanced nutrient uptake by the plants by increasing the permeability of root cell membrane, and stimulating root growth. as reported by talware et al. (2011) bulb diameter of garlic was increased with increased rate of farmyard manure. analysis of variance showed that application of 130 kg n ha-1 resulted in the optimum bulb length as compared with other treatments and control (table 5). this is because of the fact that nitrogen is responsible for vegetative growth of plants and later it increases the bulb length. in line with this finding, zaman et al. (2011) indicated that the highest length of bulb (3.12 cm) was recorded in response to the application of 150 kg n ha-1 followed by 200 kg n ha-1 (3.05 cm) and 250 kg n ha-1 (3.03 cm) whereas the lowest bulb length (2.28 cm) was found in the control plots that received no fertilizer. talware et al. (2011) also reported that bulb length of garlic revealed that bulb length was significantly influenced by different treatments of nutrients management. 3.3.2. clove weight the main effects of both vc and n application rates significantly (p < 0.05) influenced mean clove weight (table 5). the highest clove weights were recorded at the application rate of 7.5 t ha-1 which was increased by 22.62% over the control treatment (table 5). the increased mean clove weight due to the increase in vc rate could be due to vc which is known to contain micronutrients apart from major nutrients. pramanik et al., (2007) also reported that humic acids released from vc enhanced nutrient uptake by the plants by increasing the permeability of root cell membrane, and stimulating root growth. verma et al. (2013) also reported that clove weight of garlic was increased significantly up to the highest dose of 5 t vc ha-1. compared to the control treatments, clove weight was significantly increased by 18.47% in response to increasing the rate of n to 130 kg ha-1. increased mean clove weight in response to increasing rate of n may be ascribed to the availability of optimum n that may have led to high mean clove weight through facilitating improved leaf growth and photosynthetic activities thereby increasing portioning of assimilate to the storage organ. this result is in conformity with the findings of wolde (2014) who reported that the highest mean clove weight (4.42 g) was with 138 kg n ha-1application rate over the control treatment. bichi (1997) also reported that garlic clove weights obtained from plots fertilized with 69 kg and 92 kg n ha-1 were 1.82 and 1.62 g, respectively and the lowest mean clove weight was obtained from the unfertilized plots. 3.4. effects of fertilizer application on yield of garlic 3.4.1. marketable bulb yield the analysis of variance on marketable bulb yield showed significant (p < 0.05) variation due to main effect of vc and n while the interaction effect of vc and mineral n fertilizer did not show significant differences (table 6). the maximum level of vc (7.5 t vc ha-1) revealed 43.26 % yield advantage over the control treatment. this result could be associated with vc application in which plots treated with vc showed to establish better compared with those untreated plots. because vc might have provided enough nutrients and avoid competition for nutrients, and hence produced better clove and bulb that contribute for better marketable bulb yield. in fikru and fikreyohannes response of garlic to vermicompost and mineral nitrogen fertilizers 165 agreement with this, best quality garlic can be produced through application of balanced fertilizers (cantwell et al., 2006).pramanik et al. (2007) explained that humic acids released from vc enhanced ‘nutrient uptake’ by the plants by increasing the permeability of root cell membrane, and stimulating root growth. this increases marketable bulb yield due to adequate nutrient that contribute for good shape and higher bulb size that accounts for marketable bulb yield. similarly, alemu et al. (2016) reported that increased vc from 0 to 5 t ha-1 increased garlic bulb yield by 10%. as observed from this result application of maximum level of n fertilizer (130 kg n ha-1) increased the proportion of marketable bulb yield of garlic by 29.17% over control (table 6). this is due to n attributes as it is so vital because it is an essential constituent of metabolically active compounds such as of proteins, enzymes, and vitamins in plants, and is a part of the essential photosynthetic molecule and chlorophyll (mukherjee, 1993). this all may have caused ? garlic to bear quality bulbs that would contribute to its marketability. in line with this result, kilgori et al. (2007) reported a significantly increased cured bulb yield of garlic with increased n from 0 to 120 kg ha-1. maksoud et al. (1984) also reported significantly increased yield of cured marketable bulbs of garlic from 12.4 to 20.5 t ha-1 in two garlic cultivars with the addition of n at 360 kg ha-1. arboleya and garcia (1993) also observed an increased marketable bulb yield from 4.66 t ha-1 at 0 kg n ha-1 to 8.04 t ha-1 at 225 kg n ha -1. table 5. main effects of application of vermicompost and nitrogen in bulb length and clove weight on garlic. factor treatment bulb length (cm) clove weight (g/clove) vc (t ha-1) 0 2.86d 2.21d 2.5 3.02c 2.34c 5 3.13b 2.56b 7.5 3.31a 2.71a lsd (0.05) 0.08 0.12 n (kg ha-1) 0 2.86d 2.22d 52.5 2.92d 2.36dc 80 3.04c 2.42bc 105 3.19b 2.51ab 130 3.37a 2.63a lsd (0.05) 0.10 0.15 cv % 2.78 5.36 note: means followed by the same letter within a column are not significantly different at 5% level of significance 3.4.2. unmarketable bulb yield unmarketable bulb yield was significantly (p < 0.05) influenced by the main effect of vc and nitrogen fertilizer rates and their interaction effects. combination of vc and n at the rate of 7.5 t ha-1 and 130 kg n ha-1 produced significantly the lowest proportion of unmarketable bulb yield (0.46 t ha-1) over the other combinations rates (table 7). maximum proportion of unmarketable bulb yield (0.78 t ha-1) was recorded at the combination rate of nil vc and nil mineral nitrogen. this result could indicate that the potential of vc and inorganic n fertilizers combination reduced the proportion of unmarketable yield when they are applied together than they are applied separately. imbalanced fertilization and absence of application of micronutrients, less or no use of organic manures could result in the depletion of soil fertility (palm et al., 1997). reduced soil fertility reduces quality and quantity of plant production. this indicates combination of nutrient is more appreciated than a single fertilizer application to reduce unmarketable bulb yield of garlic. table 6. main effects of vermicompost and nitrogen on marketable bulb yield of garlic. factor treatment marketable bulb yield (t ha-1) vc (t ha-1) 0 8.6d 2.5 10.1c 5 11.32b 7.5 12.32a lsd (0.05) 0.60 n(kg ha-1) 0 9.36d 52.5 9.92cd 80 10.38c 105 11.17b 130 12.09a lsd (0.05) 0.71 cv % 5.69 note: means followed by the same letter within a column are not significantly different at 5% level of significance. table 7. interaction effect of nitrogen and vermicompost on unmarketable bulb yield of garlic. treatment unmarketable bulb yield (t ha-1) nitrogen (kg ha-1) vermicompost (t ha-1) 0 2.5 5 7.5 0 0.78i 0.76hi 0.75ghi 0.73efghi 52.5 0.74fghi 0.73efghi 0.71defghi 0.69cdefgh 80 0.71defghi 0.68cdefg 0.66cde 0.64cdef 105 0.69cdefgh 0.67cdef 0.65cd 0.56b 130 0.66cde 0.64cd 0.62bc 0.46a lsd (0.05) 0.076 cv% 3.86 note: means followed by the same letter within a table are not significantly different at 5% level of significance complementary use of chemical fertilizers and organic fertilizers has assumed great importance nowadays to maintain as well as sustain a higher level of soil fertility and crop productivity (shalini et al., 2002). some of the works who did on different sources and levels of fikru and fikreyohannes east african journal of sciences volume 13 (2) 149-158 166 nitrogen fertilizer indicated that higher marketable yield of garlic due to application of nitrogen was attributed to significantly higher bulb yield (maryam et al., 2012). higher marketable yield of garlic was observed in plots fertilized with high vc and n rates ha-1. the possible justification for this higher result could be due to combined effect of the contributions of vc and nitrogen to chlorophyll, enzymes, and proteins synthesis. 3.5. economic analysis as indicated in table 8, partial economic analysis was done for economic performance of garlic under vc and mineral n fertilizer application. the variable cost considered was vc and mineral n fertilizer cost with their application cost as well as extended days for gardener (60 etb per (day + night) of each treatment over control was considered. table 8. partial budget analysis of the economic performance of garlic under vermicompost and mineral n fertilizer. factors treatments average yield (t ha-1) adjusted yield (t ha-1) gross benefit (etb ha-1) total variable cost (etb ha-1) net benefit (etb ha-1) %mrr vc (t ha-1) n (kg ha-1) 0 0 7.69 6.92 276840 --276840 -- 52.5 8.07 7.27 290628 1810 288818 761.77 80 8.45 7.61 304200 2587 301613 1057.60 105 9.19 8.27 330840 3299 327541 1636.86 130 9.60 8.64 345600 4012 341588 1713.86 2.5 0 9.26 8.33 333360 26450 306910 213.69 52.5 9.59 8.63 345240 28260 316980 242.04 80 9.93 8.94 357480 29037 328443 277.71 105 10.66 9.59 383760 29749 354011 359.41 130 11.07 9.96 398520 30462 368058 399.45 5 0 9.66 8.69 347760 52900 294860 134.06 52.5 10.83 9.75 389880 54710 335170 206.62 80 11.24 10.12 404640 55487 349153 230.32 105 12.12 10.91 436320 56199 380121 283.78 130 12.74 11.47 458640 56912 401728 319.44 7.5 0 10.83 9.75 389880 79350 310530 142.46 52.5 11.19 10.07 402840 81160 321680 155.25 80 11.90 10.71 428400 81937 346463 184.97 105 12.71 11.44 457560 82649 374911 218.66 130 14.94 13.44 537600 83362 454238 312.80 note: price of n = 26.09 etb kg-1 n + application cost of 320.00 etb per ha-1. price of vermicompost = 10.00 etb kg-1 + application cost of 1390.00 etb per 2.5 t ha-1 or 2780.00 etb per 5 t ha-1 + 4170.00 etb per 7.5 t ha-1. garlic selling price = 40.00 etb kg-1. (garlic selling price at haramaya district, 2017). 4. conclusion agronomic traits and yield of garlic were significantly affected by the application of both organic and inorganic fertilizers. yield components and yield traits showed significant differences (p < 0.05) in response to the application of vc and mineral nitrogen fertilizer. the maximum clove weight (2.71 g) and marketable bulb yield (12.32 t ha-1) were recorded at the rate of 7.5 t vc ha-1. using combined application of vc at 7.5 t ha-1 and mineral n fertilizer at 130 kg ha-1, unmarketable bulb yield was reduced by 41.03% over control (no application). the highest net benefit of 454,238 etb ha1 was obtained from the highest total variable cost of 83,362 etb ha-1. the combined application of 7.5 t vc ha-1 and 130 kg n ha-1 respectively, resulted in higher marketable bulb yield than other low doses of either vc and mineral n fertilizer or their combination. the results of the experiment revealed that agronomic traits and yield of garlic plants did not reach optimum since all significantly increased in response to the application of each of the fertilizers or the combined highest rates of the fertilizers. 5. acknowledgements this work is part of an ms.c thesis conducted at haramaya university. the authors thank the ministry of education for providing financial support and haramaya university for providing the necessary facilities for the study and the research work. 6. references abreham mulatu and essubalew getachew. 2015. the effects of nitrogen and phosphorus on yield and yield components of garlic (allium sativum l) varieties at beressa watershed, mesqan woreda, fikru and fikreyohannes response of garlic to vermicompost and mineral nitrogen fertilizers 167 south central-ethiopia. global j. of agric. and agril. sci. 3 (2), 197-202 pp. agarwal sunita. 1999. study of vermicomposting of domestic waste and the effects of vermicompost on growth of some vegetable crops. phd., thesis rajasthan, jaipur, india. alemu degwale, nigussie dechassa andfikreyohannes gedamu. 2016. effect of vermicompost on growth, yield and quality of garlic (allium sativum l.) in enebse sar midir district, northwestern ethiopia. j. of natural sci. res. 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old brahmaputra flood plain soil. bangladesh j. agril. res. 36 (2): 357-367. zhou, y., wang, d., zhu, j., liu, q. and fan, m.x. 2005. the role of sulfur fertilizers in balanced fertilization. in: l.j. de kok and e. schnug (eds.), proceedings of the 1stsino-german workshop on aspects of sulphur nutrition of plants, 23-27. may 2004 in shenyang, china, landbauforschung volkenrode, special issue 283, pp. 171-176. microsoft word paper-2 (proof revised) final.docx ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (1) 13-22 _____________________________________________________________________________________________ licensed under a creative commons *corresponding author. e-mail: ewonetu2011@gmail.com attribution-non-commercial 4.0 international license. performance of white leghorn chickens breed maintained at haramaya university poultry farm and implications for sustainable poultry production ewonetu kebede senbeta* and kasaye assefa balcha school of animal and range sciences, haramaya university, p. o. box 138, dire dawa, ethiopia abstract: indigenous chickens in ethiopia are characterized by slow growth and egg production potential. as a result, poultry enterprises in the country entirely depend on exotic breeds, which are productive. the white leghorn breed is the major one among the exotic breeds. haramaya university poultry farm is a source of the white leghorn poultry breed in eastern ethiopia. however, poor management and maintenance of the breed for too long without genetic improvement is a serious constraint to enhancing poultry production in the region. the objective of this study was, therefore, to evaluate the performance of white leghorn breed maintained at haramaya university poultry farm and establish their current reproductive and productive potential. the productive and reproductive performance of the breed was evaluated starting from hatching to 50 weeks of age. 576 eggs with an average size of 50.01 + 5.57g were randomly arranged into three replicates each consisting of 192 eggs. then, a total of 363 hatched chicks were used and intensively raised on a deep litter system to evaluate body weight, feed intake, feed efficiency, body weight gain, mortality during brooder, grower and layer stages whereas egg weight and hen day egg production at layer ages were also determined. all data were analyzed using descriptive statistics. the results revealed that the mean hatchability, day old body weight, age at sexual maturity, weight at sexual maturity, hen-day egg production, and egg weight for the study breed were 70.32 + 4.08%, 33.48 + 0.84g, 154 days, 880.04 g, 70.35+3.22% and 53.47+2.39g, respectively. the average body weight and feed intake increased progressively during the brooder, grower and layer age. the highest weight gain was achieved during the grower age but the highest feed conversion ratio was observed during the layer stage. the mean mortality rates during the brooder and grower stages were 4.23+1.72 and 1.17+0.96, respectively. in conclusion, the white leghorn breed at the university performed poorly with respect to most of the variables studied. therefore, it is necessary to do more research to get insights into possible environmental and genetic factors that have contributed to the lower performance of the breed so as to address the constraints and enhance poultry production in the region. keywords: brooder; day-old chicks; grower; layer; management stages; performance; reproductive; white leghorn 1. introduction the ethiopian indigenous chickens are characterized by slow growth, late maturity and low egg production performance which are estimated at 60 small eggs with thick shells and a deep yellow yolk color (yami and dessie, 1997; niraj et al., 2014). local chickens kept under the intensive management systems are inferior to exotic stock in health status and they are also slow in rate of feathering and exhibit recurrent outbreaks of disease (solomon, 2004). because of these characteristics of local chickens, poultry breeding industries involving intensive management systems entirely depends on exotic breeds. among the many exotic breeds in ethiopia, white leghorn was imported to jimma and haramaya university in 1953 and 1956, respectively, under usaid project (solomon, 2007). since then several studies were conducted on the breed’s productive and reproductive performance in different parts of ethiopia (teketel, 1986; brannang and persson, 1990; abebe, 1992; solomon, 2004 and 2007). white leghorn chickens are known for laying large number of eggs, need less feed, and very efficient layers (haftu, 2016). the study conducted by solomon (2004) at jimma college of agriculture characterized the breed during the brooding (60 days) and reported 34 g, 5.2 g, 5.8, 8.1% for daily feed intake, daily weight gain, feed conversion efficiency, and mortality, respectively whereas during the growing period (90 days) the author reported 109 g, 11.4 g, 8.9, 6.5 % for daily feed intake, daily weight gain, and feed conversion efficiency, respectively. the body weight of the breed at 6 months ranged from 1300 g at haramaya university (abebe, 1992) to 1660 g at awassa university (teketel, 1986). besides, brannang and persson (1990) reported mean ewonetu and kasaye east african journal of sciences volume 14 (1) 13-22 14 body weight of 1050 g at an age of 5 months for the breed at assela. this breed lays an average of 280 per year and sometimes reaches 300 or even 320 as cited by ewonetu (2017). in pakistan, at faisalabad university of agriculture, ahmad et al. (2010) reported 97.84-98.16 g daily feed intake per bird, 86.87-88.14 % hen day egg production, 1.19-1.22 feed conversion ratio per dozen egg, and 25.50-29.70 g weight gain for the single comb white leghorns in their first laying year cycle (20 weeks of laying period). besides, in india, thirunavukkarasu et al. (2006) evaluated the single comb white leghorn layers at 60, 65 and 70 weeks of age for mean hen day egg production and reported 76.34, 79.06, and 76.04%, respectively. moreover, the performance of the breed during the 12 weeks of age evaluated for daily weight gain, daily feed intake, feed conversion ratio and mortality were 3.88 g, 27.48 g, and 18.38 %, respectively, at haramaya university poultry research farm (ewonetu, 2017). from the above background, it is clear that a number of studies have been conducted on characterization of the breed in different parts of ethiopia and other countries. however, limited research has been conducted to understand the whole life cycle of the breed from the age of hatching to the end of laying stage as well as to elucidate the associated constraints that may hamper realization of reproductive and productive potential of the white leghorn breed. university has been maintaining this breed at its poultry farm since 1956 and is disseminating chicks to households that engage in small-scale poultry farming in the region (ewonetu, 2017). to date, the farm is maintaining a small population of the breed and conserving a whole population as one unit by multiplying generation after generation from the population by non-random mating. consequently, such mating may result in an overall reduction in performance due to inbreeding (troianou et al., 2018). this reduction may be manifested in many ways such as poorer productive and reproductive efficiency including higher mortality rates, lower growth rates, and lower hen day egg production (kutter and nitter, 1997; as cited by udeh and omeje, 2011). this breed has not been extensively characterized for too many years. thus, evaluation of the productive and reproductive potential of the breed’s whole life cycle is necessary to understand the present performance and future consequences of the poultry farming at the university and in the region as a whole. therefore, the objective of this study was to evaluate the productive and reproductive performance of the white leghorn breed being maintained under an intensive management system at haramaya university. 2. materials and methods 2.1. study area the experiment was conducted at the poultry farm on the main campus of haramaya university. the main campus of haramaya university is located in the hararghe zone of the oromia regional state in the eastern part of the country, at a distance of about 510 km from addis ababa. the campus is situated at a distance of 5 km from the nearby town of haramaya, which is found on the main road connecting the capital, addis ababa with the eastern city of harar. the geographical location of the research site is at 9o 26' n latitude and 42o3' e longitudes and an altitude of about 2010 meters above sea level. the area receives average annual rainfall of 741.6 mm. the mean annual minimum and maximum temperatures of the site are 8.25 oc and 23.4 oc, respectively, as noted by ewonetu (2017). 2.2. experimental egg collection and incubation the experiment was conducted from january 2017 to february 2018 for 13 months. a total of five hundred and seventy-six hatching eggs with an average size of 50.01 + 5.57g were collected from white leghorn breed and randomly arranged into three replicates each consisting of one hundred ninety-two eggs. the eggs were incubated at the temperature of 37.5 °c and relative humidity of 55% for eighteen days. on the 18th day of incubation, the eggs were transferred into a hatchery and further incubated for three days at the temperature of about 36.5 °c and relative humidity of 75% relative humidity. 2.3. management of chickens and feed chemical composition chicks hatched from each replicate were counted; weighed using a sensitive digital balance and the hatchability percentage was calculated using the formula described by sahin et al. (2009). a total of three hundred sixty-three chicks were randomly grouped to replications and raised for 50 weeks on deep litter. on the first day of hatching, chicks were provided with water with vitamin premix and vaccinated against diseases. the chicks in each replication were reared on the same diet composed of ground corn, soybean meal, peanut meal, wheat short, salt, limestone and vitamin premix. however, the proportion and composition of the diet were re-formulated for the chicks according to their stages of growth (table 1). the chicks were provided with feed and water on ad libitum basis. representative samples of feed ingredients were analyzed for dry matter, ether extracts, crude fiber and ash before the actual ration formulation following the procedure of proximate analysis method (aoac, 1990). besides, kjeildhal procedure was employed to determine the nitrogen (n) content of each ingredient and the crude protein content was determined by multiplying the n value with 6.25 (magomya et al., 2014). the total metabolizable energy content was calculated indirectly by using the formula presented by wiseman (1987) that is me (kcal/ kg dm) = 3951+54.4 ee–88.7 cf–40.8 ash. ewonetu and kasaye. performance of white leghorn chicken 15 table 1. feed ingredients and nutrient composition (% for dm). feed ingredient (%) management stages (weeks) mean nutrient composition (% for dm) a me kcalkg-1 brooder (0-8] grower (8-22] layer (22-50] dm cp ee ash cf ground corn 55.00 45.15 45.00 89.00 7.10 5.30 2.30 8.00 3436.88 soybean meal 12.00 15.00 17.00 93.20 38.50 8.90 8.00 9.00 3310.46 peanut meal 9.00 13.00 20.00 94.70 37.30 9.60 6.20 12.00 3155.88 wheat short 20.00 25.00 10.15 90.30 12.00 3.30 6.80 6.2.00 3303.14 limestone 3.15 1.00 7.00 vitamin premix 0.50 0.50 0.50 salt 0.35 0.35 0.35 average 91.80 23.73 6.78 5.83 8.80 3301.34 note: a dm = dry matter; cp = crude protein; ee = ether extract; cf = crude fiber and me = metabolizable energy. 2.4. body weight measurements chick live weights were taken at hatching and recorded as initial weight. then, the average weight per chicken was measured every two weeks for each replication by weighing the chickens in each pen and the total weight was divided by the total number of chickens in each replication to calculate the weight gain. the overall average body weight for two consecutive weeks was then computed by taking the average values for the replication. 2.5. feed intake and conversion ratio (fcr) weighed feed was offered once a day at 08:00 am and refuse was collected and weighed in the morning of the next day. the feed offered and refused were recorded for each replicate to determine the chicken’s daily feed intake and calculate the overall average feed intake per day per chicken. feed conversion ratio was measured by dividing feed consumed into live weight gain for each growth stages (brooder and grower) and also calculated for layers on egg production basis. 2.6. egg production and egg weight egg weight was measured individually every day for each replication using an electronic weighing balance and the average was taken for the two weeks. the mean daily hen day egg production (hdep) for each replication was calculated every two weeks using the following formula as cited by shafik et al. (2013). hdep = ( # # ) x 100 2.7. mortality deaths were recorded daily after the onset of the experiment and it was calculated for each growth stages as mortality rate at the end of the experiment. 2.8. statistical data analysis data entry and management was made using microsoft excel sheets and all data were finally analyzed using statistical analysis system version 9.1.3 (sas, 2008) for descriptive statistics such as mean, percentage, and standard deviation. 3. results and discussion 3.1. hatchability the average hatchability based on total eggs set reported in this study was lower (70.32 + 4.08%) than results reported by abraham and yayneshet (2010) in northern ethiopia (76.1%), kebede et al. (2014) in other region of ethiopia (78.6-81.4%) and islam et al. (2002) at bangladesh livestock research institute (86.1%) for the same breed. this hatchability variation against the same breed might be due to the differences in egg weight used for incubation, age of parent flocks from which the eggs were obtained, and management given to parental flocks as found in many previous studies. for instance, ulmerfranco et al. (2010) reported lower hatchability in eggs that were larger than the average egg. however, dewitt and schwalbach (2004) reported that large size eggs have higher hatchability in new hampshire and rhode island red chicken breeds at 30 week of age. similarly, wilson (1991) also reported that large-sized eggs had a higher hatchability value than mediumand small-sized eggs. moreover, yassin et al. (2008) gave an account of breeder factors that affect hatchability such as strain, health, nutrition and age of the flock, egg size, weight and quality, egg storage duration and conditions, egg sanitation, and season of the year. 3.2. day-old body weight the average day-old body weight recorded in this study was 33.5 + 0.84 g which is lower than the hatchling weight (42 g) recorded for the same breed at jimma college of agriculture (solomon, 2004). likewise, islam et al. (2002) reported higher average chick weight (38.96 g) for the same breed at bangladesh livestock research institute. however, similar results were reported by zewdu and berhan (2013) concerning average one-dayold body weight (33.88 ± 1.8 g) for the same breed at haramaya university poultry farm. fahey et al. (2007) also reported almost a similar result (33.1 ± 1.04g) for the body weight of one-day-old white leghorn chicks. ewonetu and kasaye east african journal of sciences volume 14 (1) 13-22 16 however, barua et al. (1992) reported lower (25.48g) average one-day-old body weight for the same breed at bangladesh agricultural university poultry farm. this variation in day-old weight might be due to the differences in non-genetic parameters given for parental flocks and also might be the influence of study agroecologies. the influence of non-genetic factors like feeding practices, flock management, housing, and season on production performance such as day-old body weight were reported in earlier studies (hossen, 2010; ochieng et al., 2011). besides, rudra et al. (2018) noticed the effect of feed, environmental conditions, and climatic conditions in different agro-ecologies on live weight of chickens. moreover, suarez et al. (1997) reported that chick weight at hatch is heavily influenced by the weight of the egg from which it hatched. 3.3. age and weight at sexual maturity the average age at sexual maturity measured as age at first egg was attained at about 154 days (5.13 months) for the breed. this result falls within the range of 149169 days as reported for the same breed under extensive management by solomon (2007) at jimma college of agriculture in ethiopia. however, a relatively earlier maturation was attained for the same breed at the mean age of 139 days at swedish university of agricultural sciences, skara (dominic et al., 2012), 138.31 ± 3.44 days in india (reddy et al., 2001) and 149 days (solomon, 2004) at jimma college of agriculture in ethiopia. on the contrary, the late age for sexual maturity of 175.2±7.6 days (khalil et al., 2004), 192 days (goto et al., 2011) and 245±6.08 days (addis and malede, 2014) were reported for white leghorn in previous studies. on the other hand, the average weight at sexual maturity for this breed was attained at about 880.04 g and this was lower than the weight at first egg reported for the same breed at bangladesh agricultural university poultry farm (1352.67g; barua et al., 1992) and at indian veterinary college and research institute (1400.16±23.25g; thirunavukkarasu et al., 2007). the late age for sexual maturation of the breed in this study might be due to smaller egg weight (50.01 + 5.57g) used for hatching which may result in smaller day-old weight (33.48 + 0.84g). table 2. white leghorn chicken characterization at brooder ages (mean + sd). age (weeks) bw(g) bwg (g) fi (g) fcr (weight) mortality (%) 0-2 49.45+3.32 2.28 + 0.14 13.24+0.68 0.14+0.02 6.20+1.63 2-4 97.77+5.01 4.62 + 0.28 26.68+4.14 0.15+0.01 5.02+1.96 4-6 160.21+7.06 4.30 + 0.23 49.14+3.87 0.28+0.01 3.07+1.73 6-8 216.66+11.32 3.77 + 0.67 71.42+5.69 0.48+0.08 2.64+1.78 note: bw= body weight, bwg = body weight gain, fi= feed intake, fcr = feed conversion ratio. table 3. white leghorn chicken characterization at grower/pullet ages (mean + sd). age (weeks) bw(g) a bwg (g) fi(g) fcr (weight) mortality (%) 9-10 270.60+26.18 3.94+1.58 81.97+6.54 1.40+0.28 1.81+0.97 10-12 328.98+34.52 4.40+0.65 89.57+6.54 1.46+0.30 1.26+1.42 12-14 379.46+29.25 2.81+0.46 92.55+8.33 2.31+0.41 0.97+0.96 14-16 431.27+26.13 4.59+1.91 97.59+8.30 1.64+0.84 0.66+0.57 16-18 487.95+28.85 3.51+1.20 103.10+9.76 1.68+0.57 nmr 18-20 570.34+26.13 8.12+1.39 107.63+11.74 0.57+0.21 nmr 20-22 753.11+73.30 18.13+8.94 110.52+13.25 0.34+0.29 nmr note: bw=body weight, bwg =body weight gain, fi= feed intake, fcr= feed conversion ratio nmr=no mortality record. ewonetu and kasaye performance of white leghorn chicken 17 table 4. white leghorn chicken characterization at layer ages (mean + sd). age (weeks) bw(g) bwg (g) fi (g) hdep (%) ew (g) fcr (egg) 22-24 661.73+41.87 0.33+3.35 116.49+17.36 26.42+6.21 49.10+3.69 1.73+1.03 24-26 811.62+46.56 0.83+3.04 123.85+11.30 48.72+6.63 50.49+2.76 2.98+2.45 26-28 961.51+66.00 9.30+10.20 129.99+5.55 55.17+6.43 51.58+2.04 2.48 +3.07 28-30 1067.39+69.85 5.83+7.72 133.36+5.70 62.14+8.66 52.28+1.61 1.27 + 0.93 30-32 1104.15+37.26 -0.58+5.06 136.62+5.10 65.03+7.22 52.55+1.54 2.88+1.98 32-34 1120.05+56.57 2.87+2.10 139.59+4.28 68.86+4.61 52.86+2.05 7.74+10.22 34-36 1163.71+12.33 3.39+4.63 142.95+3.77 74.17+0.57 53.17+2.03 5.40+38.45 36-38 1139.22+65.92 -6.89+7.78 146.35+4.43 75.70+1.26 53.77+2.29 3.11+3.31 38-40 1124.00+26.12 4.71+16.96 153.50+5.85 80.73+0.20 54.41+2.38 2.11+2.58 40-42 1155.47+52.77 1.35+5.87 175.57+17.29 83.64+0.81 55.07+2.74 2.61+2.94 42-44 1186.94+82.31 1.36+5.86 189.36+5.87 85.37+1.77 55.48+2.76 10.09+7.66 44-46 1177.38+15.63 -1.13+0.71 199.54+8.16 85.58+1.39 55.67+2.86 7.41+14.46 46-48 1171.60+23.26 -1.06+8.35 201.79+8.57 86.31+1.39 56.02+2.51 2.80+1.30 48-50 1226.98+72.93 8.98+4.53 212.59+6.60 87.04+0.23 56.12+2.48 2.30 + 1.80 note: bw=body weight, bwg= body weight gain, fi= feed intake, fcr= feed conversion ratio, hdep=hen day egg production, ew=egg weight. table 5. white leghorn chicken characterization at different age groups (mean + sd). parameters (mean + sd) brooder (0-8) grower (9-21) layer (22-50) body weight (gbird-1) 132.47+6.87 505.51+36.79 1127.88+10.48 feed intake (gbird-1) 40.12+3.48 97.56+8.86 157.26+7.55 weight gain (gbird-1day-1) 3.74+0.24 6.50 + 1.21 2.09+0.15 feed conversion ratio 0.26 +0.03 1.34+0.13 6.06 +2.55 3.4. egg production and weight the overall average hen-day egg production (70.35+3.22%) recorded in this study was lower than 86.87 ± 0.35, 88.14 ± 0.93 and 87.55 ± 0.38% reported for the same breed in pakistan (ahmad et al., 2010) (table 4). besides, higher egg laying percentage were reported for white leghorn reared on floor (81.297 ± 23.994%) and in cages (80.681a± 23.946) from 20-40 weeks in mexico (itza-ortiz et al., 2016). however, lower percentages of hen day egg production (58.25-69.9) were reported for white leghorn breed within 22-38 weeks (promila et al., 2017). the hen day egg production (hdep) was increased with advance in age (table 4). the lower percent of hen-day egg production in this study could be attributed to the variations in environmental conditions provided to the breed. moreover, the diverse age at first egg of chickens might lead to higher differences in hdep due to the positive correlation between hen age and body weight with egg production which is consistent with the results reported by malik et al. (2008). the average egg weight for the breed from 22-50 weeks was 53.47+2.39 g/egg which was lower than other results (57.801 ± 4.039 and 57.702 ± 5.073 g) reported for white leghorn in pakistan (ahmad et al., 2010). besides, islam et al. (2002) reported higher average egg weight (59.48g) for the same breed at bangladesh livestock research institute. however; tamasgen (2015) noted relatively lower egg weight (51-52 g) for the same breed at haramaya university poultry research farm. the egg weight was increased with the layer’s age (table 4). this concurs with the results of earlier studies that showed increased egg weights with increased age of hens (lukáš et al., 2009; padhi et al., 2013). the diverse age at first egg of chickens might lead to higher differences in egg weight due to the positive correlation between hen age and egg weight which is consistent with earlier reports (niknafs et al., 2012). 3.5. body weight and gain the biweekly weight taken for the study breed was progressively increased during the brooder, grower and layer age (table 2, 3, and 4). the body weight recorded at brooder and grower age (table 5) was lower than 350 g and 1400 g, respectively. similar results were reported at the same age for the same breed by solomon (2004). besides, the body weight recorded at the age of 24-26 weeks (table 4) was lower than the body weight (1300 g) recorded during the same age for the same breed at the same study site (abebe, 1992). moreover; brannang and persson (1990) reported higher body weight (1050 g) at the age of 20-22 weeks for white leghorn than the results recorded in this study for the same age. moreover, dominic et al. (2012) reported higher body weight (1629.3±110.4) for the breed at 28-30 weeks. the daily body weight gain of the breed during the brooder, grower and layer age groups are presented in tables 2, 3, and 4, respectively. higher body weight gain was recorded during the grower than brooder and layer periods (table 5). the higher daily weight gain (5.2 and 11.4g) was reported at 60 and 90 days of ages, ewonetu and kasaye east african journal of sciences volume 14 (1) 13-22 18 respectively, for the same breed at jimma college of agriculture (solomon, 2004). the decreased and/ or negative daily body weight gain observed during the layer stage (table 5) might be to compensate daily egg production rate. 3.6. feed intake and efficiency the daily feed intake per bird calculated on daily basis for the breed at brooder, grower and layer stages were increased with advanced age and egg production (tables 2-4). this result was consistent with the findings of abiola et al. (2008) who observed an increased daily feed intake with increase in the weight of chickens though it varied from breed to breed. lower feed intake for the same breed were reported during the first (97 ± 1.8 105 ± 1.9), second (108 ± 0.5111 ± 2.5) and third (109 ± 1.47120 ± 1.61g) months of laying (jesus eduardo et al., 2013). besides; ahmad et al. (2010) reported lower feed intake (98.00±0.10, 98.16±0.33, 97.84±0.28g) for white leghorn layers from the point of lay to 40 weeks of age in pakistan. the feed conversion ratio on body weight basis during brooder age was increased with age (table 2). higher dry matter feed conversion (4.92-5.97) was reported for the same during the brooder age (zewdu and berhan, 2014). in addition, solomon (2004) reported 5.8 and 8.9 feed conversion efficiency, respectively, for white leghorn during the brooding and growing periods. however, lower layers feed conversion was reported during the first, second and third months from 1.71 ± 0.031.84 ± 0.04, 1.85 ± 0.031.92 ± 0.04 and 2.03 ± 0.032.07 ± 0.06, respectively (jesus eduardo et al., 2013). moreover, ahmad et al. (2010) reported lower feed conversion ratio per dozen eggs (1.19±0.009-1.22±0.009) for the same breed in pakistan during their first laying year cycle. the variation in feed intake and feed efficiency for the same breed in different study sites might be related to variation in provided environmental conditions such as nutrition, temperature, humidity, rate of lay, egg weight, body weight, and type of housing. likewise, scott (2005) quoted the influence of nutrient energy content, environmental temperature, stocking density, feeder space and water availability on chicken feed intake and efficiency. among environmental factors, temperature is commonly assumed to be the most important factor influencing chicken health, behavior and production (webster and czarick, 2000). if there are variations of temperature according to different locations within the poultry house, then chickens will consume lesser or greater amounts of nutrients than required hence productive and reproductive differ greatly and the great fluctuation in house temperature during cold weather may lead to poor feed conversion ratio and to health problems (talha et al., 2011). 3.7. mortality although high mortality rate was recorded during the first eight weeks of brooding age, it was sustained throughout the growing period to sixteen weeks of age and it was significantly reduced with advanced age (table 2 and 3). however, mortality was not recorded after sixteen weeks (table 3). this might be due to resistance development to disease with advanced age. the mortality rates recorded during brooder (table 2) and grower (table 3) stages were relatively lower than the mortality rates reported during brooder (8.1%) and grower periods (6.5%), respectively, for the same breed (solomon, 2004). a higher mortality rate (7.1%) was also reported by kebede et al. (2014) for the breed under intensive management condition. very high mortality rates for white leghorn brooders (48.8%), growers (48.5%) and layers (21.3%) were reported for the breed under extensive management conditions in northern ethiopia (abraham and yayneshet, 2010). moreover, barua et al. (1992) reported higher average mortality rate (15%) for the white leghorn in bangladesh from the age of hatching to 23 weeks. the variation in mortality rate of the same breed as compared to previous studies at different study sites or in different countries could be due to the variation in study agro-ecologies and health management on the farm such as disease-prevention management techniques and hygienic practices at the farm level. the risk of disease introduction and the related economic impact due to mortality was minimized by strict application of disease-prevention management techniques and hygienic practices at the farm level (marangon and busani, 2006). the fluctuation of chicken’s body temperature is somewhat depending upon the temperature of its environment or study agroecologies and the effect of stress caused by elevated temperatures can result in heavy economic losses from increased mortality and reduced productivity (st-pierre et al., 2003). furthermore, the cold weather in poultry house and at any study location may lead to poor feed conversion ratio and to health problems (talha et al., 2011). 4. conclusion the results of this study have demonstrated that the mean hatchability, day-old body weight, age at sexual maturity, weight at sexual maturity, hen-day egg production and egg weight of the study breed were 70.32 + 4.08%, 33.48 + 0.84g, 154 days, 880.04 g, 70.35+3.22% and 53.47+2.39g, respectively. the body weight and feed intake were increased progressively during the brooder, grower and layer age groups whereas higher weight gain was achieved during grower ages. however, the highest feed conversion ratio was observed for the layer stage. the mortality rates during brooder and grower stage were 4.23+1.72 and 1.17+0.96, respectively. in general, compared to the performances of white leghorn chickens researched by other researchers in other places, study sites, the white leghorn chickens in this study area performed less in most variables investigated. therefore, control mating design by establishing sire and dam lines and then recurrent selection within breed on different set of traits should be applied to improve the productive and reproductive performance of the breed. this study was ewonetu and kasaye performance of white leghorn chicken 19 conducted from day-old to 50 weeks of age; therefore, similar studies should be conducted including the third cycle laying stage to evaluate the whole life productive and reproductive performance of the breed. further studies should also be conducted on the breed to understand the specific cause of their lower performance and evaluate inbreeding coefficients of the population in the farm. 5. acknowledgements the authors would like to thank haramaya university, particularly office of enterprise directorate for funding the research. the authors also express sincere gratitude to all staff working at haramaya university’s poultry farm for actively facilitating the study. 6. 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e.e. 2010. hatching egg characteristics, chick quality, and broiler performance at 2 breeder flock ages and from 3 egg weights. poultry science, 89: 2735-2742. webster, a.b. and czarick, m. 2000. temperatures and performance in a tunnel-ventilated, high-rise layer house. journal of applied poultry research, 9: 118-129. wilson, h. r. 1991. interrelationships of egg size, chick size, posthatching growth and hatchability. world poultry science journal, 47; 5-20. wiseman, j. 1987. feeding of non-ruminant livestock. butterworth and c ltd, 370. yami, a. and dessie, t. 1997. the status of poultry research and development in ethiopia, pp. 40-60. in: fifth national conference of ethiopian society of animal production (esap), 15-17 may 1997, addis ababa ethiopia. yassin, h., velthuis, a.g.j., boerjan, m., van riel, j. and huirne r.b.m. 2008. field study on broiler eggs hatchability. poultry science, 87: 2408-2417. zewdu, w. and berhan, t. 2013. the effect of feeding different levels of brewer’s dried grain yeast mixture on the performance of white leghorn chicks. international journal of scientific and research publications, 3: 1-5. ewonetu and kasaye east african journal of sciences volume 14 (1) 13-22 22 1 east african journal of sciences (2019) volume 13 (2) 195-206 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: shimelisemire@yahoo.com attribution-noncommercial 4.0 international license. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) nutrient dense dairy product diversification and quality evaluation shimelis e. admassu* school of chemical and bio-engineering, food process engineering graduate program, addis ababa university, p. o. box 33381, addis ababa, ethiopia abstract: there are limited diversified dairy products manufactured in dairy industries, and an increased demand for diversified dairy products in ethiopia. to this end, there is un-met demand for nutrient rich dairy diversified products. this research was conducted with the aim to perform product development and quality assessment of yogurt with some cereals and legumes with the implication for diversification of nutrient dense yoghurt products in order to explore market potential. yoghurt enriched with cereals and legumes was investigated for nutritional, microbial, texture and viscosity analyses as well as sensory quality attributes. yogurts were processed through inoculation of milk with lactobacillus bulgaricus and streptococcus thermophiles. finger millet yogurt was significantly better in protein and minerals composition. furthermore, fat and ash values were high in finger millet yogurt: 3.47 and 2.36 g 102g-1; respectively. common bean (redwolaita variety) yoghurt had abundant concertation of calcium next to finger millet-yoghurt. the aerobic plate count (2.3x102 cfu ml-1), coliform (<1x101 cfu ml-1), yeasts and mold (<1x101 cfu ml-1) of yoghurt comply with the microbiological standard requirements. pathogenic bacteria such as salmonella, e. coli, s.aureus, shigella spp and b.cereus were absent in all the yogurt samples. the processed yogurt products possessed complementary effect of nutrient enhancement which is driven from cereals and legumes. the product has very good acceptability by panelists and revealed excellent nutritional composition. the processing technology also provided high nutrient dense, acceptable in quality and microbiologically safe products. the results from the proximate, physico-chemical, microbiological, and texture and viscosity analyses indicate that yogurt with cereals and pulses possess good nutritional composition. the processing technology provided microbiologically non-hazardous end products, and the results from the sensory evaluation of revealed that value added products can be a potential dairy product that fit to the lifestyle of consumers and get accepted. these findings further suggest investors currently involved in the dairy sector can produce products that fit into consumers’ lifestyle by pioneering technology transfer of this research output in order to capture the un-met consumer demand for safe, nutritious, affordable and proprietary nutrient dense yogurt production. keywords: cereals; fermentation; legumes; milk; nutrient dense; quality; yogurt 1. introduction dairy products are an excellent source of nutrition and contribute to income generation. given the considerable potential for smallholder income and employment generation from high-value dairy products, the development of the dairy sector in ethiopia can contribute significantly to poverty alleviation and nutrition improvement. the excess demand for diversified and processed dairy products in the country is expected to induce rapid growth in the dairy sector. factors contributing to this excess demand include rapid population growth, increased urbanization, consumer preference, consumer’s income growth, population size, price of the product, price of substitutes and other factors (idf, 2018; eiar, 2013). the long-term success of a dairy plant depends on getting the right products for the market on time. the achievement of a dairy plant depends on implementing competent processing operations and on its new product development capabilities. thus, it is of paramount importance to assess the gap and pick the right, nutritious and health benefit of dairy product via innovative/adaptive research and technology transfer. yoghurt is one of the utmost prevalent fermented milk products worldwide and has grown consumer acceptance as a healthy food. yogurt clasps the secrets behind good health and have many nutritional characteristics (staffolo et al., 2004). nowadays, the nature of dairy products (yoghurt types) is, of course, changing to meet new consumer demands and/or expand into new market, but the essential characteristics of the products have not altered (tamim and robinson, 1999). cereal grains and leguminous seeds contain myriad components that are important and essential to human health. studies have shown that dietary fibers and certain phytochemicals found in cereals and pulses can be key to health maintenance and disease risk reduction. intakes of dietary fibers and phytochemicals have been associated with reduced risk of cancer, cardiovascular disease, diabetes, chronic inflammation, neural degeneration, and other chronic ailments and illnesses. these bioactives are, therefore, good candidates as ingredients for nutraceuticals and functional foods (liangli et al, 2012). accordingly, enrichment of yoghurt with cereals and grain legumes can improve the nutritional quality and important to human health. shimelis east african journal of sciences volume 13 (2) 195-206 196 in the last five years (2012-2017) dairy industries emerged intensely in ethiopia due to the increased demand of milk and milk products and good business opportunities. with the present trend characterized by market-oriented economy, the dairy sector appears to be moving towards a take-off stage. one of the indicators in the dairy sector motivation is that currently more than 89 private dairy industries operate in different parts of ethiopia with various level of technology, processing capacity, and trained manpower. the microbial quality of raw milk is crucial for the production of quality dairy foods. hygienic milk production practices, proper handling, transportation and storage of milk, and mandatory pasteurization has decreased the threat of milk-borne diseases such as tuberculosis, brucellosis, and typhoid fever (de buyser, 2001). there have been a number of food-borne illnesses resulting from the ingestion of raw milk, or dairy products made with milk that was not properly pasteurized or was poorly handled causing postprocessing contamination. in milk, the microorganisms that are principally involved in spoilage are psychrotrophic organisms. most psychrotrophs are destroyed by pasteurization temperatures, however, some like pseudomonas fluorescens, pseudomonas fragi can produce proteolytic and lipolytic extracellular enzymes which are heat stable and capable of causing spoilage. some species and strains of bacillus cereus, clostridium, cornebacterium, arthrobacter, lactobacillus, microbacterium, micrococcus, and streptococcus can survive pasteurization and grow at refrigeration temperatures which can cause spoilage problems (vasavada, 1988). the consumer’s interest in fermented dairy products is gaining momentum due to the development of new food processing techniques, changing social attitudes; scientific evidence of health benefits of certain ingredients (stanton et al., 2001). the concept of diversification in this research lays on enrichment of yoghurt with grains in order to improve the nutrients in the final product, and exploit resource utilization via product diversification. incorporation of cereals and legumes facilitate increment in composition of nutrients which are not viable in yogurt alone. the new (potential) diversified yogurt product was selected by taking into account the nutritional point of view, acceptability by the consumers, technology transfer options via adaptive research, health benefits to the society and resource mobilization. the aim of the present work was, therefore, t o design and develop yoghurt with cereals and legumes and undertakes evaluation of physico-chemical, microbiological and sensory quality attributes which in turn drive consumer preferences prior to the large scale production and introduction of the end product to the market. the outcome of this study will enhance and inform stakeholders in the dairy industry about the potential and implication of yoghurt diversification in ethiopia. 2. materials and methods 2.1. experimental materials, chemical and reagents the basic materials for yogurt production were cow’s milk, dairy ingredients, various cereals and legumes such as finger millet, maize, common beans, broad beans, wheat and sorghum (figure 1) and packaging materials. the grain legumes and cereals used in this study were collected from melkassa agricultural research center and debrezeit agricultural research center. sufficient number of legumes and cereals samples were taken, rinsed five times in deionized water to eliminate any adhering substances, dried in ventilation oven at 65oc for 24h. cleaned and dried samples were placed in plastic containers and stored at room temperature before use. the processing and quality control equipment used include fermenter, incubator, sterilizer, pasteurizer, autoclave, texture analyzer, viscoanalyzer and other milk processing apparatus. the dairy ingredient specifically the direct vat set (dvs) freeze‐dried thermophilic starter culture (fd-dvs, yfl811 yo-flex®) for manufacturing of yoghurt consists of lactobacillus delbrueckii subsp. bulgaricus and streptococcus thermophilus was obtained from chr hansen, denmark (figure 2). the direct vat set yf-l811 yoghurt starter culture is suitable to produce yogurt with very mild flavor, very high viscosity and very low post-acidification. the starter culture is suitable for cup set and presented in form of freeze-dried culture for direct inoculation. recommended inoculation rate is 50u (one sachet) dvs culture for 250 liters’ milk to be inoculated. the yogurt culture was stored at -18oc before use. all chemicals and reagents for nutritional composition, minerals and microbiological analyses were provided by sigma-aldrich (st. louis, missouri, usa) through local suppliers. all chemicals used were analytical grade. http://en.wikipedia.org/wiki/market shimelis enriched yoghurt with cereals and legumes 197 figure1. finger millet and various pulses (redwolayta, awash and tabor) figure 2. thermophilic yoghurt culture, yf-l811 (source: chr hansen, denmark) 2.2. manufacturing of yogurt with cereals and legumes the main processing steps involved in set yogurt manufacture include the standardization of milk, homogenization, milk heat treatment, incubation/ fermentation, cooling and storage (figure 4). yogurt was prepared by fermentation of milk with bacterial cultures consisting of a mixture of streptococcus subsp. thermophilus and lactobacillus delbrueckii subsp. bulgaricus. the equipments used for set yogurt production were milk separator-standardizer, pasteurizer, homogenizer, packaging unit, incubator/bioreactor and autoclave. the starter culture was whipped at the top with disinfecting solution (70 % ethanol) and cut at the top of the sachet. to reduce bacteriophage infection, spatula, milk pails, milk cans, beakers, measuring cylinder, funnel and scissors were sterilized using sterilizer at 121 oc for 30 minutes (sordina, italy, 2006). initially, the fermenter (40l, bioengineering, england, 2005) (figure 3) was sterilized at 121oc using steam to maintain the safety of the starter culture and final product. figure 3. fermenter (40l, bioengineering, england, 2005) finger millet pulses shimelis east african journal of sciences volume 13 (2) 195-206 198 variety of yogurt products with cereals and legumes were produced at addis ababa university, food process engineering laboratory according to standard method described by ramesh et al., (2006), figure 4. standardized, homogenized and pasteurized milk was used for product development. the various ingredients such as skim milk powder and stabilizer together with milk (50 liters) were then blended together in a mix tank equipped with agitation system. the mixture was heated to 95 0c with holding time of 30 minutes, stirred at 250 rpm in bioreactor. foam and air introduction into the milk were avoided. once the heat treatment has been completed, the milk is cooled to just above the desired incubation temperature (47oc) to allow for heat loss during inoculation, and then dosed with a starter culture. the required amount of the yogurt starter culture to milk was calculated based on recommended inoculation rate and weighed with analytical balance (explore pro. model ep214c, switzerland, 2007). about a liter of milk was taken from the pasteurized and cooled milk to 450c and then after the weighed amount of freeze-dried granules of starter culture poured directly into milk. the mixed /prepared starter culture with milk was inoculated to the 50 litres fermenter and instantly the blades with slow agitation speed were switched on for two minutes to distribute the culture evenly. raw milk skimmed milk powder, stabilizer recombination hold for hydrolysation homogenize at 150 bars pasteurization (90-950c for 10min) cool to 40c heat to 450c-470c inoculate with culture and mix gently at 430c-450c adding pre-cooked cereals and grain legumes at the bottom of the yoghurt cups filling and packing in cups at 430c-450c incubate at 450c for 2-4hrs blast freezer/cool to below 100c storage to 4oc figure 4. main processing steps in the manufacture of enriched set yogurt. cooked cereals and grain legumes were placed at the bottom of yoghurt cups and then the inoculated milk at ph of 6.7 was layered on top and immediately covered with the lid. the fermentation process took place in the cup at incubation unit. finally, set yogurt (which includes cereals/legumes-on-the bottom) is formed in cup-package as lactic acid bacteria ferment lactose into lactic acid giving a continuous gel structure. the proportion of cereals and legumes to yoghurt weight was about 1:10. then after, the products were incubated at 45°c to ph 4.3, and then subjected to flash cooling to below 10°c. the end products were cooled and stored at 4°c in order to slow down the physical, chemical and microbiological degradation. the physical attributes of yogurts, including visual whey separation and perceived viscosity, are crucial aspects of the quality and overall sensory consumer acceptance of yogurts were investigated. the ph of yogurt samples was executed frequently using a ph-meter from the time of inoculation throughout the fermentation process. 2.3. analyses methods 2.3.1. nutritional composition the official standard methods of analysis of association of official analytical chemists (aoac, 2010) were used for physico-chemical analysis of yoghurts. total ash, crude protein, crude fiber, and crude fat of the seed grains were determined using the official test methods 923.03, 979.09, 962.09, 4.5.01; respectively. all the minerals except phosphorus were analyzed from triple acid digested samples using atomic absorption spectrophotometer (hitachi, model z-8230, japan, 2009) according to the method of isaac and johnson (1975). phosphorus content was determined colorimetrically (dickman & bray, 1940) using uv/visible spectrophotometer (model 6405, jenway ltd.uk, 1999). 2.3.2. hundred seed weight and water absorption studies one hundred-seed weight was determined by counting 100seeds using an electronic seed counter and weighing. results were expressed as the mean of triplicate determinations. for water absorption studies, samples were soaked in distilled water at 20 oc. the seeds then removed at regular intervals during soaking, dried by blotting with filter papers and weighed. the water absorbed by the seeds is calculated as a percentage of the fraction of the weight gained by seeds on soaking to the weight before soaking. 2.3.3. ph measurement the ph values of yoghurt with cereals and legumes were determined using a ph meter (hanna instruments, h301, portugal), aoac official method. the viscosity of yoghurt was measured using vibro visco-analyser at the food process engineering laboratory of addis ababa university. 2.3.4. cooking time for cereals and legumes cooking time was determined using an automated mattson cooker as described by wang and daun (2005). the automated mattson cooker consists of a cooking rack and 25 hollow plungers. the weight of each plunger is adjusted to 90 g. a sample (30 g) is soaked in distilled water at room shimelis enriched yoghurt with cereals and legumes 199 temperature (22±2°c) for 24 h. soaked seeds were then positioned into each of the 25 saddles of the rack so that the tip of each plunger rests on the surface of the seed. the rack is then placed into a 2 l metal beaker containing 1.2 l of boiling water. when a seed becomes sufficiently tender, the plunger penetrates the seed and drops a short distance through the hole in the saddle. the time taken for each plunger to drop is automatically recorded. cooking time for a sample is defined as the time required for 80% of the seeds to be penetrated. 2.3.5. texture profile the texture profile of yoghurt samples was measured according to the method described by malcolm (2002) with a lloydж, ta plus ametek, uk, 2007, texture analyzer. the texture profile analyses for yogurt samples were performed using back extrusion test principle with crosshead speed of 1mm sec-1 and probe/fixture was performed with probe of 35mm diameter extrusion disk. the maximum force was measured and recorded at a crosshead speed of 1mm sec-1. the firmness of yoghurt was expressed as the maximum force per gram of sample (n g-1 sample). all values were reported as the means of triplicate determination. 2.3.6. microbiological analysis microbiological analyses in yogurt samples were evaluated using a standard method described by sharma (2006) and ethiopian standard (2009) reference number es 3468: 2009. protocol used for the isolation of microorganism was is:5887 based on iso (1993). mold and yeasts, total coliforms count, faecal coliforms, aerobic bacterial plate count, e.coli count, s.aureus count and salmonella spp were performed using test methods es iso:6611, es iso:4832, es iso:5541-1, es iso:6610, es iso:11866, es iso: 6611 and es iso:6785 of the ethiopian standard; respectively. aoac official method of analysis (2010), test method 980.31 was used for the enumeration and identification of b. cereus. food and drug administration bacteriological analytical manual (rhodehamel and harmon, 2001) was used for the enumeration and identification of shigella spp. 2.3.7. sensory quality evaluation sensory quality evaluation of yogurt products was performed to better understand attributes of a product that drive consumer preferences and consequently enable processors to optimize a product’s attributes to attract specific target consumers as well as accurately monitor product quality. in view of this a sensory evaluation was carried out by 35 male and female panelists selected from consumers group and people who are familiar with quality attributes of dairy products. the sensory quality evaluation was conducted using a 5point hedonic scale adapted from resurreccion (1998) indicating degree of liking for color, appearance, taste, after taste, flavor (taste + odor), aroma, consistency, acidity and overall acceptability. the test consists of a 5-points hedonic scale ranging from like extremely, through neither like nor dislike, to dislike extremely, with varying number of categories. the panelists were given the processed yogurt samples with cereals and legumes (figure 5). after providing orientation samples were presented alongside with the hedonic test form, and the panelists were asked to rate each sensory attributes employed in the evaluation of the sensory quality of yogurt. the 1-5 categories on the evaluation scale were 1 = dislike extremely, 2 = dislike moderately, 3 = neither like nor dislike 4 = like moderately and 5 = like extremely. figure 5. processed yoghurt with cereal and pulse products 2.4. statistical analysis data were subjected to analysis of variance (anova). where the anova test indicated significant differences and treatment means were separated using duncan’s multiple range test at 5% probability level. shimelis east african journal of sciences volume 13 (2) 195-206 200 3. results and discussion 3.1. proximate and mineral composition of yogurt enriched with cereals and legumes the quality assessment results including nutritional and mineral composition analyses of yoghurt combined with cereals and pulses were presented in table 1. this research finding on protein content (table 1) is in agreement with the report of the dairy council (idf, 2018) which indicates that plain yoghurt consists of 5.7 g/100g protein, 3.0 g/100 g fat and adequate amount of different minerals. yoghurt with cereals and legumes provided nutrient dense and balanced diet from nutritional point of view. it also increases essential amino-acid composition and other very vital nutrients which were derived from the grain seeds. incorporation of various cooked grains such as maize, finger millet, haricot bean, wheat, faba bean and sorghum facilitate increment in nutrients composition which are not viable in plain yoghurt alone. crude fiber composition can also be increased via production of grain-based yogurt which in turn plays an in important role in providing choice to end-users. the fermentation pathway of set yoghurt is carried-out by the action of specific lactic acid-producing starter culture which consist of lactobacillus bulgaricus and streptococcus thermophiles bacteria coagulates the milk protein, thickening the milk and adding the characteristic sour taste. yoghurt blended with legumes and cereals reveled improved nutrient composition with dense macro-and-micro nutrient availability. the levels of soluble proteins, non-protein nitrogen and free amino acids can be higher in yogurt as a result of heat treatment to milk and breakdown of casein by starter bacteria (kim et al, 1998; karagul-yuceer, et al., 2001). lactic acid bacteria require amino acids for their growth; they break down milk proteins due to their proteolytic activity, and protein in fermented milks is reported to be totally digestible (alm, 1982a). fermented milks are more digestible than milk due to proteolytic activity of starter bacteria resulting in higher levels of peptides and amino acids. the mineral content is hardly altered during fermentation; however, reports suggest that the utilization of ca, p, and fe in the body is better for fermented milks than that of milk (ramesh et al., 2006). table 1. proximate composition of yoghurt developed with cereals and legumes expressed in g/100g dm and minerals mg/100g. product protein crude fat crude fiber ash ca zn fe cu p yoghurt (commercial) yoghurt (plain) 5. 62 5.70 3.22 3.00 0.00 0.08 0.81 0.76 147.00 149.40 0.29 0.32 0.49 0.57 0.02 0.01 118.98 115.79 yoghurt with finger millet 10.83 3.47 2.42 2.36 235.90 2.34 2.24 0.75 129.99 yoghurt with maize 8.74 3.39 0.86 1.13 187.50 0.42 0.21 0.43 124.74 yoghurt with wheat 9.73 3.89 1.40 1.40 191.25 1.06 1.11 0.48 138.03 yoghurt with sorghum (meko-1) 8.31 3.96 1.17 1.23 158.40 0.82 1.49 0.45 142.49 yoghurt with kidney beans (roba) 9.00 4.19 1.99 1.95 209.39 0.80 1.67 0.39 135.21 yoghurt with haricot beans (redwolaita) 8.73 4.06 1.97 1.97 220.42 1.11 2.19 0.52 139.36 yoghurt with french beans (tabor) 8.77 3.71 1.84 1.83 206.14 0.79 1.63 0.51 125.94 yoghurt with navy beans (awash) 9.35 3.75 1.78 1.92 205.05 0.83 1.83 0.53 126.46 yoghurt with dry beans (beshbesh) 8.97 3.64 1..90 1.73 205.95 1.10 1.26 0.63 122.27 yoghurt with faba beans 10.11 3.81 2.53 2.02 200.25 0.79 1.06 0.94 143.49 note: all values are means of triplicate determination where dm-dry matter yogurt is highly nutritious healthy food and is an excellent source of protein, calcium and potassium (mohammed et al., 2017). the mineral profile of yogurt prepared from cereals and pulses increased significantly compared to the control sample (plain yogurt) due to the availability of rich amount of minerals both in cereals and pulses. yoghurt made with cooked finger millet seeds revealed rational amount of calcium compared to other yoghurts made of cereals and pulses. this can be explained due to the high amount of calcium in finger millets (tadesse variety) which is 248 mg per 100 g of edible portion reported by shimelis et al. (2009). the yoghurt made with beans (roba variety) also resembles high amount of calcium next to products made from yogurt with finger millet and redwolaita grains. the yoghurt samples which contained roba and redwolita bean varieties consists of 209.39 and 220.42 mg/100g calcium content; respectively. in particular, yoghurt can provide the body with significant amounts of calcium in a bioavailable form. according to the research report by shimelis and rakshit (2005) that, the improved roba was the best variety in terms of food making quality and supplementary bean-based processed foods including fortified products to combat the problem of protein-energy malnutrition in east and great lakes regions of africa. this nutrient dense yoghurt product enriched with beans (raba variety) can be used as supplementary food source for lactating mothers and children. the research findings published by shimelis et al (2009) revealed that the chemical composition of finger millet varieties among which tadesse variety has rich amount of ca, fe, zn, cu, cr, mg, mn and p. hence, using finger millet seeds for yogurt making as ingredient can bring balanced diet shimelis enriched yoghurt with cereals and legumes 201 for pregnant women, children and elder people in order to maintain healthier lifestyle. yogurt is a component of the dietary approaches to stop hypertension diet designed to reduce the risk of high blood pressure (kim et al., 1998). utilization of nutrients’ dense yogurt can enhance nutritional function such as improvement of protein digestibility, alleviation of lactose intolerance, enhancing of mineral absorption. according to tannock, (1990, 1999), yoghurt has also physiological effects including control of intestinal heath, lowering serum cholesterol, antihypertensive effects, anticancer effects and effect on immunological function. consumption of fermented milks has been reported to inhibit infection and alleviation of allergies (mitsuoka, 1978). the processed products provide an array of nutrients in significant amounts, in relation to its energy and fat content, making it a nutrient‐dense food. furthermore, yoghurt has many health benefits beyond the basic nutrition it provides, such as improved lactose tolerance, a possible role in body weight and fat loss, and a variety of health attributes associated with probiotic bacteria. yoghurt with finger millets and faba beans revealed higher in protein, 10.83 mg/100g and 10.11 mg/100g composition; respectively. the calcium concentration is higher in yoghurt with finger millet and yoghurt with haricot beans. it can be concluded that yoghurt manufactured from finger millet, beans and wheat revealed comparatively better nutrient dense yoghurt products. overall, addition of cereals and legumes in yogurt as dairy products can maximize the nutrients bioavailability and make best use of cereal-legume-based yoghurts which in turn increase the overall nutritional composition of the final product and offer health benefits. 3.2. physico-chemical properties the physico-chemical properties of cereals and legumes such as seed weight, h a r d n e s s , water absorbed, unhydrated seeds and cooking time of ten cereals and legumes are presented in table 2. table 2. physico-chemical properties of cereals and legumes used for yoghurt processing. grains seed weight (g/100 seeds) hardnessa (ng-1) water absorbed (%) unhydrated seedsb (%) cooking time (min) roba 18.98±0.01 129.64±0.22 167.36±0.02 18.13±0.02 24.03±0.01 beshbesh 19.35±0.01 136.96±0.96 165.41±0.57 21.76±0.01 26.61±0.06 awash 16.91±0.02 118.09±0.42 227.29±0.12 1.52±0.01 19.50±0.05 redwolaita 21.92±0.01 140.98±0.95 154.82±0.06 31.59±0.02 28.55±0.10 tabor 18.29±0.05 127.55±0.97 167.50±0.03 5.24±0.01 23.60±0.06 finger millet 15.38±0.21 87.57±0.56 327.23±0.23 0.49±0.04 17.03±0.05 maize 24.34±0.25 151.34±0.68 138.25±0.34 35.79±0.09 32.09±0.10 wheat 17.22±0.23 123.27±0.57 192.33±0.45 3.24±0.07 21.31±0.34 sorghum (meko-1) 16.06±0.41 116.09±0.38 232.07±0.32 1.48±0.35 19.12±0.05 faba bean 54.33±0.92 138.21±0.23 157.77±0.34 29.68±0.48 27.31±0.07 note: asamples were cooked for their corresponding cooking times determined using the mattson-cooker.; bcalculated as a percentage of number of unhydrated seeds after soaking over night to the total number of seeds which initially has a weight o f 100 g. unhydrated seeds (hard o r non-soakers) pe r c e n ta ge among t h e food grains varied from 1.52 to 35.79, the highest being in maize and the lowest being in finger millet. the number of unhydrated seeds after soaking is also an indication f o r their respective cooking t i m e . the higher alteration in unhydrated s e e d s among grains clearly indicates the variation in water absorbed. based on these results, differences in cooking quality has revealed. unhydrated seeds are unde sir able , and would increase cooking time. they are correlated negatively with water absorbed and positively correlated with cooking time. physico-chemical characteristics are important parameters, which ultimately play an important role in cooking cereals and legumes. the results of the present study are consistent with those mentioned by previous workers (latunda, 1991; bishnoi and khetarpaul, 1993; wang et al., 2010a) for food legumes. investigators r e p o r te d that the legumes h a v i n g the higher water absorbed require less cooking time. the consumers and processors alike prefer grains with low cooking time and low hardness value. a large water absorbed l e a d s to better c o o k i n g quality (less cooking time and texture), s o is ultimately desirable to the end-user. as cooking of some of the cereals and legumes would provide soft texture with the yoghurt products, less fuel and energy, consumers should be preferred. cooking time is one of the main considerations used for evaluating g r a i n s cooking q u a l i t y . longer c o o k i n g times result in a loss of nutrients a n d could limit enduses. hence, consideration of cooking time is of utmost importance. the results obtained f o r cooking properties of food grains are given in table 2. awash and https://www.researchgate.net/publication/222309759_variability_in_physico-chemical_properties_and_nutrient_composition_of_different_pea_cultivars?el=1_x_8&enrichid=rgreq-069c7ad7-8c72-4c0a-aa1d-b363f1a5b500&enrichsource=y292zxjqywdloziymja4mjmzmjtbuzoyntkzmdm0njy1otg0mdbamtqzodgznde3mjmxoa== https://www.researchgate.net/publication/229804329_relationship_between_physicochemical_and_cooking_properties_and_effect_of_cooking_on_antinutrients_of_yellow_field_peas_pisum_sativum?el=1_x_8&enrichid=rgreq-069c7ad7-8c72-4c0a-aa1d-b363f1a5b500&enrichsource=y292zxjqywdloziymja4mjmzmjtbuzoyntkzmdm0njy1otg0mdbamtqzodgznde3mjmxoa== https://www.researchgate.net/publication/229804329_relationship_between_physicochemical_and_cooking_properties_and_effect_of_cooking_on_antinutrients_of_yellow_field_peas_pisum_sativum?el=1_x_8&enrichid=rgreq-069c7ad7-8c72-4c0a-aa1d-b363f1a5b500&enrichsource=y292zxjqywdloziymja4mjmzmjtbuzoyntkzmdm0njy1otg0mdbamtqzodgznde3mjmxoa== shimelis east african journal of sciences volume 13 (2) 195-206 202 maize required the minimum and maximum cooking time of 19.50 and 32.09 min, respectively. the hardness of the cooked grains is defined, as the maximum force required for 75% deformation of seeds after cooking. the force required for seed deformation was less for finger miler and this also had the smallest cooking time. hardness ranged from 118.09 to 151.34 n g-1, the highest being in maize and the lowest being in awash (table 2). hardness values have similar correlation trends in cooking time reported by shimelis and sudip (2005). the force required to compress the cooked legumes and cereals increased with increasing cooking time. cook-ability has been reported (salunkhe, 1982) to depend upon such factors as growing conditions, handling and storage, and chemical composition. in general, consumers prefer quicker cooking times. cooking times may vary based on a number of factors, including storage conditions of the pulses and cereal grains, elevation, agronomic practices and water hardness. cooking provide tender texture, reduce antinutrients composition, maximize minerals bioavailability and also increase in-vitro protein digestibility (shimelis and rakshit, 2005; emire and sudip, 2006; shimelis and rakshit, 2007, emire and rakshit, 2008). 3.3. microbiological quality and texture profile analysis of products the microbiological analyses result presented in table 3, shows that the microorganism population in yoghurt samples was 2.3 x 105 cfu/g, which is in agreement with the findings reported by mohammed et al (2017) and karagulyuceer (2001). the results for coliform count, mold and yeasts, aerobic bacteria plate count (apc) and fecal coliform were <1x101, < 1x101, 2.3x102 and < 1x101 cfu g1; respectively. coliforms test result indicates the hygienic practices and post-pasteurization contamination. consequently, the result shows that coliforms do not survive pasteurization process and acceptable food safety management system. another test, which has a strong bearing on the shelf life of yoghurt, is yeast and mold count. yeast and mould population levels, fecal coliform, e-coli and s.aureus were less than the finding of farinde et al.(2009) and akanbi and oyediji (2015). the result also comply with the microbiological requirement specified in ethiopian standard es 3468:2009 for e-coli, salmonella spp, s.aureus, mold and yeasts. the result of microbiological analysis, therefore, revealed the absences of photogenic microorganisms which can bring food borne diseases in yoghurt tested samples. pathogenic microorganism comprising b.cereus, s.aureus, e.coli, salmonella and shigella spp were not detected in yoghurt. this confidence stems from the fact that the severe heat treatment received by the process milk, together with the low ph of the end product, make set yoghurt extremely safe in respect to public health where for none of the recognized pathogens can survive or grow below ph 4.3. in addition, there is good evidence that metabolites such as antibiotics released by the yoghurt organisms can actively depress the viability of any enteric pathogens like campylobacter, escherichia or salmonella spp. (zourari et al.1992). 3.4. texture analysis of yoghurt with finger millet the experimental result on texture analysis displayed in table 4 and show that yogurt with finger millet has 3398 n g-1. the value for viscosity (2.45m pa.s) was compared to the research finding of salvador and fiszman, (2004) and shimelis and worku (2010, 2011), revealed that it is higher than pasteurized milk (1.22 mpa.s) and kefir (1.58 mpa.s); respectively. the young’s modulus also one of the indictors for texture profile and reveals 1.038 mpa. the youghrt with finger millet has a wonderful smooth texture with a delightful creamy mouth-feel low resistant to flow. the conditions of incubation including temperature-time regimes of fermentation play an important role in controlling the texture of set yoghurt. additionally, the impact of processing conditions on texture development may help to improve the quality of yogurt with finger millet. 3.5 ph value and incubation time for yoghurt the ph value of yoghurt with cereals and legumes after incubation time of three hrs changed from 6.6 to 4.9 (figure 5). very importantly, incubation of set yoghurt took place in retail containers (plastic cups) until the required ph (around 4.4-4.7) is reached. table 3. microbiological analysis of yoghurt with cereals and legumes types of microbiological analysis load in cfu/ml coliform count < 1x101 yeasts mold < 1x101 apc 2.3x102 fecal coliform < 1x101 e. coli absent s. aureus absent b.cereus absent salmonella absent shigella spp absent note: cfu-coliform unit; apc-aerobic bacteria plate count; *in the count < 1x101 is the standard reporting format for plates from all dilution of the sample has no colonies. excessive acidity, as a result of continued starter activity during prolonged storage above 5 oc, can also be a problem, because the acid-tolerant lb. delbrueckii subsp. bulgaricus has the ability to generate lactic acid to levels of 1.7% or above. such a level is too harsh for the palates of most consumers, and it is this postproduction acidification that, in general, tends to determine the shelf-life of commercial yoghurt (zourari et al.1992). furthermore, enhanced acidification to ph values below 4 may lead to body and texture defects shimelis enriched yoghurt with cereals and legumes 203 such as gel shrinkage and syneresis. table 4. texture and viscosity analysis results for yoghurt with finger millet. parameters used units results viscosity mpa.s 2.45 firmness n g-1 3398 young’s modulus mpa 1.038 load at maximum load (n 0.894 3.6 sensory quality evaluation the sensory quality evaluation of yoghurt was performed approximately 24 hrs after packaging and presented in table 5. the mean sensory scores of the organoleptic evaluation for all the yoghurt samples are shown in table 5. the statistical analysis revealed that there were significant (p <0.05) differences in the sensory attributes observed. the lactic acid bacteria and yeast fermentation of milk results in the production of numerous components, including lactic acid, co2, a small amount of alcohol, and an array of aromatic molecules, all of which provide yoghurt with its exclusive organoleptic properties. based on organoleptic assessment, it was observed that yoghurt with cereals/pulses had very good acceptabilty by gruop of panalists. the sensory evaluation result showed significant differences (0.05<p) in all the organoleptic attributes analysed. thsus, the organoleptic assessment in this study showed that the products had good qualitative characteristics. table 5. sensory properties of yoghurt with cereals and legumes. sensory attributes mean ± sd appearance 3.70 ± 0.97 taste 4.10 ± 0.81 after taste 4.02 ± 1.04 flavor 3.82 ± 1.01 aroma 3.18 ± 0.96 consistency 3.92 ± 0.99 color 3.98 ± 0.98 acidity 3.75 ± 0.96 overall acceptability 3.86 ± 0.88 grand mean 3.81 ± 0.96 note: mean is calculated using values of 5 (like extremely) and 1 (dislike extremely); hence, a high mean indicates highly rated attribute; hedonic rating scale (1 to 5); where:1=dislike extremely; 2=dislike moderately; 3 = neither like nor dislike 4 = like moderately; 5 = like extremely. according to tamime and robinson (1999), the proper quality of fermented milk depends on pasteurization at a temperature of 85-95°c for 5-30 minutes. it is significant because the influence of heat-treatment on the improvement in coagulation and viscosity of the yoghurt is correlated with the degree of denaturation of lactoglobulinβ which, interacting with casein, significantly influences the yoghurt's texture (dannenberg and kessler, 1988a). in conformity with literature, the peak degree of interaction takes place at 85°c for 30 minutes and heating milk below 85°c and above 120°c causes a distinct decrease in the clot consistency. product development is the lifeblood of the diary food industry. furthermore, it is very important for food businesses, scientists and policy-makers to understand consumers of food products. this in turn helps to develop successful products and gain/retain consumer confidence. consumers' requirements and desires are affected by issues such as culture, age and gender while issues that are important to consumers nowadays includes health will not always be so significant. therefore, food businesses and policy-makers need to understand consumers' attitudes and influences upon them in order to respond effectively (hal, 2007). in a nutshell, sensory perception towards consumerled food product development and food acceptance plays an important role for food businesses innovation and process technology. the technology in processing of yogurt with cereals and legumes is a new concept for ethiopian consumers. thus, specific products were tested at laboratory scale and the result was impressive. accordingly, the dairy processing industry can commercialize this innovative idea via large scale production. conducting marketing intelligence to select the best suitable cereal/pulse-based or mixtures of cereals-legumes-pulses with yoghurt in the ethiopian context require further study for the specific and targeted product design and development. the new products posses’ complementary effect of cereals and pulses in general. additionally, production of yoghurt with grains can improve the nutritional status of the young generation in promising africa and increase farm gate price for small-holder farmers and encourage producing more cereals and legumes in ethiopia which can be used as an input in yoghurt manufacturing. 4. conclusions the potential of producing acceptable yoghurt enriched with cereals and legumes was investigated. the nutritional, physico-chemical, microbial and sensory analyses were implemented to find out the quality attributes of the products. the quality assessment of yogurt enriched with cereals and legumes were executed with the implication for diversification of nutrient dense yoghurt products in order to explore market potential. it is clear from the obtained research findings that, there was remarkable increase in the nutrient composition of all yoghurt products due to the possessions of complementary effect of cereals and legumes. the nutrient dense yoghurt products were highly acceptable by panelists and the shimelis east african journal of sciences volume 13 (2) 195-206 204 products were also microbiologically safe. specially, yoghurt with finger millet revealed higher protein concertation, ash content, minerals (ca, zn, fe and cu) compared to other cereals and legumes mixed yoghurts. overall, from the nutritional, physicochemical and sensory acceptability points of view, the yoghurt produced with finger millet seeds revealed the best nutrient dense acceptable product. the adaptive technology in utilization of yogurt with cereals and legumes is a potential concept of yoghurt diversification for ethiopian consumers and dairy processing industries. yoghurt products diversification should be taken as focal points in order to uphold better business development and capture the un-meet consumer demand for safe and nutritious products. in a nutshell, the results revealed that yoghurt with cereals and legumes can be processed with the existing technologies in the ethiopian context and has good nutritional composition and the processing technology provided microbiologically nonhazardous end products. 5. acknowledgments the author express sincere gratitude to the netherlands development organization (snv-ethiopia), milk value chain, boam (business organizations and their access to markets) program for financial support of this research. special thanks are due to the emppa (ethiopian milk producers and processors association) members, ethiopian institute of agricultural research and adabai agro-food industry consult for their support through the research project aafic-01-10-17. 6. references akanbi, b.o. and oyediji, k. 2015. microbiological quality of yoghurt sold in gwagwalada, abuja. nigerian journal of microbiology, 27 (1): 2630-2636. alm, l. 1982a. effects of fermentation on curd size and digestibility of milk proteins in vitro of swedish fermented milk products. journal of dairy science 65:509-514. aoac. 2010. association of official analytical chemists (aoac). official methods of analysis of the aoac international. william, h. 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diversification in ethiopia. east african journal of sciences, 5: 117-129. shimelis admassu, mulugeta teamir and dawit alemu. 2009. chemical composition of local and improved finger millet (eleusine corocana (l.) gaetrtin) varieties grown in ethiopia. ethiopian journal of health since, volume 19(1), 1-8. staffolo, m. d., bertola, n., martino, m. and bevilacgua, y. a. 2004. influence of dietary fiber addition on sensory and rheological properties of yogurt. international dairy journal, 14: 263-268. stanton, c., gardiner, g., meehan, h., collins, k., fitzgerald, g., lynch, p.b. and ross, r.p. 2001. market potential for probiotics. american journal of clinical nutrition, 73: 476s-483s. tamime, a. y. and robinson, r. k. 1999. yoghurt science and technology. cambridge: woodhead. tannock, g. w. 1990. the microecology of lactobacilli inhabiting the gastrointestinal tract. advances in microbial ecology, 11: 147-171. tannock, g. w. 1999. probiotics: a critical review. journal of antimicrobial chemotherapy, volume 43(6), p. 849. vasavada, p. c. 1988. pathogenic bacteria in milk-a review. journal of dairy science, 71(10): 2809-2816. wang, n. and daun, j. k. 2005. determination of cooking times of pulses using an automated mattson cooker apparatus. journal of the science of food and agriculture, 85: 1631-1635. wang, n., hatcher, d. w., tyler, r. t., toews, r., gawalko, e. j., 2010a. effect of cooking on the composition of beans (phaseolus vulgaris l.) and chickpeas (cicer arietinum l.). food research international, 43 (2): 589-594. zourari, a., accolas, j. p. and desmazeaud, m. j. 1992. metabolism and biochemical characteristics of yoghurt bacteria: a review. lait, 72: 1-34. ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (2) 111-120 licensed under a creative commons *corresponding author. e-mail: misganaw1129@gmail.com attribution-noncommercial 4.0 international license. adaptation of food oat (avena sativa l.) genotypes in amhara region, ethiopia misganaw ferede1*, melle tilahun1, zina demsie1, ermias abate2, molla mekonnen1, gebremariam asaye1, mequanint andualem1, fentanesh sendekie1, desalegn getaneh1, yasin taye1, and sefinew wale1 1adet agricultural research center, arari, eiar, p.o. box 08, bahir dar, ethiopia 2amhara agricultural research institute, eiar, p.o. box 527, bahir dar, ethiopia abstract background: oat is one of the soil acidity tolerant crops among cereal crops. in ethiopia, however, it is mainly cultivated for animal feed using local cultivars with poor agronomic and soil management practices in soil acidity prone areas. objective: there are a lot of improved and commercial oat varieties released by european countries that are recommended for both food and feed. therefore, the study was conducted to identify high-yielding and disease-resistant oat genotypes in acid soil highland areas of amhara region. materials and methods: the study was conducted at adet, banja, fajie, farta, geregera, sekela, sekota and sinan in the amhara regional state of ethiopia. thirteen introduced food oat genotypes and one local cultivar as a check were used as experimental treatments. the experiment was laid out as a randomized complete block design with three replications. results: the combined analysis of variance showed significant (p≤0.05) differences for grain yield and yield related traits of among genotypes, environments, and their interactions. the combined grain yield performance range was 3904 kg/ha to 3045 kg/ha in food oat genotypes. food oat genotypes g4, g5, g10, g2, g13, g8 and g12 showed higher interaction to the environmental factors and also higher in grain yielding performance than the remaining tested oat genotypes across the tested environments. therefore, these genotypes are relatively wider in adaptation across the tested environments. however, food oat genotypes only goslin (g4) and souris (g12) were more both widely adaptable and resistance to oat diseases over the local cultivars. conclusion: among the 13 introduced food oat genotypes, goslin (g4) and souris (g12) were higher in grain yield performance, with a grain yield advantage of 26.93% and 18.16% and resistance to oat diseases over the local cultivars. therefore, food oat genotypes goslin (g4) and souris (g12) should be demonstrated and scaled out in soil acidity prone high land areas of banja, fajie, farta, geregera, sekela and sinan districts and in areas with similar agro-ecologies of ethiopia. keywords: grain yield; oat diseases; resistant; soil acidity 1. introduction oat (avena sativa l.) is an important food crop as oat grain contains high levels of β-glucan, which has been found to decrease serum glucose and cholesterol levels. in addition, the high levels of oil and protein, as well as other beneficial attributes of oat grain, offer advantages for human consumption when compared with other grain cereals (loader, 1991; douhlert et al., 2001). in proportion to other cereal crops, oat is considered to be better suited for production under marginal environments, including acidity soils and soils with low fertility (hoffmann, 1995). currently russia, canada, australia, finland and usa are the major oat producing countries (faostat, 2018). however, in ethiopia, oat is a minor crop grown in cooler highlands. oat is remaining an important crop in marginal ecologies, for grain as well as for feed. it is adapted to a wide range of soil types and can perform better than other small-grain cereals on acid soils. low soil ph and associated soil infertility problems are considered to be amongst the major challenges to acid sensitive crops production. the farmers consider it as healthy food and suitable to human health. the farmers report that the cattle also prefer oat straw to tef straw. this suggests that oat is an ideal crop for mixed farming system of acid soil affected areas as quality food and feed. currently, there is no any research and development support for oat production in the areas. on the contrary, according to the market assessment information, imported oat is sold for over 65 birr per 500g at supermarkets in urban centers like bahir dar, suggesting ample opportunity for oat production, processing and marketing. tolerant genotypes are used in rotation with crops such as potato which require acid soil (ph <5.4) so as to control potato scab disease and therefore are best options in areas where application of lime is difficult (foy et al., 1987). oat is tolerated to al-toxicity through release of malate from their roots (radmer et al., 2012). these organic acids detoxify al ion by chelating and forming al-carboxylate complex which cannot enter the mailto:misganaw1129@gmail.com misganaw et al. east african journal of sciences volume 14 (2) 111-120 112 root system (kochian et al., 2005). tolerance of oat to acid soil with high exchangeable al is controlled by dominant genes that allow easy identification and selection of tolerant lines by using simple screening protocols (nava et al., 2006; radmer et al., 2012). major limitations constraining oat production and productivity in the acid soil prone highlands are poor quality and productivity of existing cultivars. on other hand, there are high grain yielding and disease resistant oat genotypes resistant to stress environments out of ethiopia. therefore, it was important to introduce and evaluate the high yielding and diseases resistant oat genotypes. the study was conducted with the objective of to identify high yielding and acidic soil tolerant oat genotypes with resistance to economically important disease in soil acidity prone highlands of amhara region. 2. materials and methods 2.1. description of experimental sites, materials and procedures the study was conducted at adet and farta (potential areas), banja, sinan, sekela and fajie (soil acidity prone highland areas), sekota and geregera (moisture deficit highland areas) in 2017 cropping season. the experimental environments are depicted in tables 1 and 2, respectively. table 1. the description of agro ecological information of environments. environment geographical location altitude (m.a.s.l.) latitude longitude adet 2238 11o16՛n 37o29՛e farta 2706 11o51՛n 38o01՛e sekela 2490 10o51՛n 37o08՛e banja 2560 10o57՛n 36o56՛e sekota 2266 12o38՛n 39o02՛e sinan 2782 10o32՛n 37o43՛e fajie 2840 09o41՛n 39o32՛e geregera 2865 10o68՛n 38o68՛e note: data organized from ethiopia metrological agency (bahirdar branch) and gps and m.a.s.l ₌ meters above sea level. table 2. soil physio-chemical properties of the study areas. location soil physico-chemical data ph ex. acidity ex. al %oc %n p ppm cec banja 5.29 0.25 3.01 0.25 23.75 28.91 farta 5.41 1.92 0.14 26.96 35.65 sekela 5.30 0.21 0.00 3.55 0.28 15.64 27.70 sinan 5.3 1.2 0.09 1.60 10.90 note: data on soil physical and chemical properties were sourced from soil analysis laboratory of adet agricultural research center. thirteen introduced oat genotypes and one local cultivar as check were used as experimental treatments. the trail was laid out in randomized complete block design with three replications. each genotype was planted on 6 rows with 2.5 m length. spacing between rows, plots, and replications were 0.2 m, 0.4 m, and 1.5 m, respectively. the gross and net harvestable plot area were 2.5m x 1.2m and 2.5m by 0.8 m respectively. seed, nitrogen+phosphorus+sulphur (nps) and urea fertilizers were used at rates of 100,100 and 50 kg ha-1, respectively. planting was carried out from end of may to 2nd week of july in 2017 cropping season. all nps and one third of urea was applied at planting while the remaining two third of urea was top dressed at tillering just after first weeding. misganaw et al. adaptation of food oat genotypes 113 table 3. pedigree, origin and growth habit food oat genotypes for the study. genotype pedigree origin growth habit chaps ogle (brave/unnamed_336)x unnamed_5458(il755667/ogle) illinois spring florida501 florad (floriland irradiated/unknown) x unnamed_6485(unnamed_6484/unnamed_6483) florida winter gem (x6166-2) wi x6051 (mo 07468/unnamed_4882) x ogle (brave/unnamed_336) wisconsin spring goslin oa952-3(oa797-7/02540-3-7-2) x 06196(pc48/oa952-3) ottawa spring horizon ck92ab719/horizon314 florida winter kangaroo unnamed_15143(sv88123-104/wa84q406) x sv86153_101(unnamed_11891/unknown) australia winter noble-2 noble(tippecanoe/unnamed_10546) x noble(tippecanoe/unnamed_10546) minnesota spring oa600-32 na na na oa602-4 na na na pusa hybrid g unknown india unknown souris(nd961161) nd90141(nd894904/nd852107) x nd900118(mn78142/nd852158) north dakota spring tam 0-397 re-selection from tamo386(tamo-386/tamo -386) x reselection from tamo-386(tamo-386/tamo-386) texas winter ufrgs930605 unknown brazil winter local ethiopian cultivar na = not available. 2.2. data collection and statistical analyses data were collected on days to physiological maturity, plant height, panicle length, number of seeds per spike, thousand seed weight, straw yield, grain yield and disease severity and reaction of the varieties. data on days to physiological maturity was collected at 75% of the harvestable plot area become physiologically mature. the agronomic traits, namely, plant height, panicle length, and number of seeds per panicle data were collected from randomly selected 5 plants per plot whereas straw yield and grain yield data were collected on the harvestable plot area per plot across environments. thousand seed weight was measured from the randomly taken thousand seed in each plot counted by electronic seed counter. the oat rust diseases severity scoring was done based on cobb modified scoring method (peterson et al., 1948). the oat rust and scab diseases varietal reaction/response scoring was done based on cobb modified scale (stakman et al., 1962). oat leaf blotch was scored based on modified version of saari and prescott’s scale of two digits scoring system (00-99: the 1st digit is appearance of disease on plant height whereas the 2nd digit represents the severity % of the disease) (saari and prescott, 1975). the data were analyzed using genstat statistical software (17thedn). the ammi analysis of variance summarizes most of the magnitude of genotype by environment interactions into one or a few interaction principal component axes (ipca) (crossa, 1990). least significant difference (lsd) method (p<0.05) was used for mean separation among genotypes. 3. results and discussion 3.1. analysis of variance of grain yield and yield related traits of food oat genotypes the combined analysis of variance of varieties, environments and their interactions showed the presence of significant (p≤0.05) difference among varieties for days to maturity, plant height, panicle length, and number of seeds per panicle, thousand seed weight, straw dry biomass and grain yield (table 4). the higher variation due to the main effect of varieties on panicle length was 71.08 % followed by plant height (57.05 %) and thousand seed weight (51.52 %) and whereas the higher variation expressed by environment main effect on straw dry biomass was 87.83% followed by number of seeds per panicle (70.39%) and grain yield (69.04) in food oat genotypes. the findings of this study were in line with as atefah and sohbat (2012) reported in oat genotypes. in addition, the variation accounted by the interaction of genotypes by environments on thousand seed weight was (39.39%) followed by straw dry biomass and grain yield were 24.86 % and 24.54%, respectively. according to atefah and sohbat (2012) and mushtag et al. (2013) report, higher variations on grain yield and number of seeds per panicle response was accounted by environment main effects where as higher variations on plant height and thousand seed weight was accounted by genotype main effects and higher variations scored on straw yield due to the interaction of genotypes by environments. misganaw et al. east african journal of sciences volume 14 (2) 111-120 114 table 4. the ammi analysis of variances accounted by genotypes, environments and their interaction of food oat varieties across environments. trait gen ss env ss g*e ss ipca1 ipca2 error ss % ss gen % ss env % ss g*e dm 16470 160641 7125 3894** 1297** 2760 8.94 87.19 3.87 ph 108777 72261 9642 4649** 2125** 7992 57.05 37.89 5.06 pl 4872 1026 956 454** 234 ns 1629 71.08 14.97 13.95 nspp 20553 92299 18258 13289** 2718 ns 13996 15.68 70.39 13.93 tsw 5724 1028 4359 3365** 433* 1814 51.52 9.25 39.23 sdm 18365 15546 11186 5605** 5134** 8667 40.83 34.31 24.86 gy 1436 15433 5485 1595** 1443** 3611 6.42 69.04 24.54 note: dm = days to physiological maturity; ph = plant height; pl = panicle length; nspp = number of seed per panicle; tsw = thousand seed weight; sdm = straw dry biomass; gy = grain yield; ** = significant at 0.01; gen = genotype; env = environments; gen*env = genotype by environment interactions; ipca = interaction principal component axis; df = degree of freedom; ss = sum squares; vr = variance ratio and f pr = f-probability. 3.2. performance of grain yield and yield related traits of food oat genotypes the performance of yield related traits of food oat genotypes are depicted in table 5. the maturity time of food oat genotypes range was from 138.1 and 138.2 days for the genotypes horizon and ufrgs930605, respectively and 164.2 days for the genotype kangaroo across environments. the plant height in oat genotypes varies 89.2 cm to 153.1 cm for the genotypes ufrgs930605 and oa602-4 respectively. the panicle length in oat genotypes varies 15.7 cm to 29.1 cm for ufrgs930605 and chaps, respectively. the studies reported by amanuel et al. (2019), dawit and mulusew (2017), mushtag (2013), yasemin (2012) and nehvi et al.(2007) the analysis of variances showed significant differences in oat genotypes. here, in the study, the performance of yield related traits were varied in oat genotypes as per the tested materials, environments and their interactions. as showed in table 6, analysis of variances of grain yield performance showed significant (p<0.05) differences for genotypes, environments and their interactions. the combined grain yield performance range was 3904 to 3045 kg ha-1 in food oat genotypes. as amanuel et al. (2019), zeki et al. (2018), dawit and muluse (2017), atefah and sohbat (2012) and yasemin (2012) and nehvi et al. (2007) studies the grain yield performance was different in the oat genotypes across environments. as a result, the performance of grain yield and yield related traits of oat genotypes were significantly affected by the main genetic, environmental and interaction of genotype by environment effects. table 5. the phenological and agronomic traits response of food oat genotypes across environments. genotype trait dm ph (cm) pl (cm) nspp tsw (g) sdm (kg ha-1) chaps(g1) 155.9 129.4 29.1 76.9 34.1 6620 florida501(g2) 148.7 120.4 21.0 57.6 37.9 4900 gem(g3) 156.8 122.0 18.7 58.4 35.5 6210 goslin(g4) 150.3 127.5 23.3 79.9 38.7 5690 horizon(g5) 138.1 103.1 20.6 58.0 32.2 3170 kangaroo(g6) 164.2 126.9 23.0 51.8 40.2 4670 local(g7) 156.9 146.7 27.8 78.4 33.5 5870 noble-2(g8) 150.1 137.9 25.0 74.0 40.9 5190 oa600-32(g9) 153.4 149.6 27.7 76.5 39.4 6570 oa602-4(g10) 155.2 153.1 28.1 66.3 43.6 5300 pusahybridg (g11) 147.0 117.9 20.5 60.1 29.6 4560 souris(g12) 150.0 115.4 23.5 75.0 33.3 5250 tam 0-397(g13) 145.7 103.8 23.7 55.1 36.3 4210 ufrgs930605(g14) 138.2 89.2 15.7 60.1 29.5 2810 mean 150.8 124.5 23.4 66.3 36.0 5070 cv(%) 2.6 5.8 12.7 20.2 8.7 22.3 lsd(5%) 6.2 11.6 4.8 21.8 5.1 1840 gen ** ** ** ** ** ** env ** ** ** ** ** ** gen*env ** * ** ** ** ** note: dm = days to physiological maturity; ph = plant height; pl = panicle length; nspp = number of seed per panicle; tsw = thousand seed weight; sdm = straw dry biomass; ** = significant at 0.01; gen = genotype; env = environments and gen*env = genotype by environment interactions. misganaw et al. adaptation of food oat genotypes 115 table 6. the grain yield (kg ha-1) performance of the food oat genotypes across environments. genotype environment mean grain yield yield advantage over local (%) adet farta sekela banja sekota sinan fajie geregera chaps 5101a 4935ab 4012abcd 2583abcd 3665abc 2551d 3132cd 2510abc 3565abcd 17.08 florida501 4682ab 4082bcd 3386def 2644abcd 3684abc 4037a 4806a 2877a 3768ab 23.74 gem 3625cd 4066bcd 3115f 2660abcd 3103cdef 2853cd 3551bcd 2275bc 3155de 3.61 goslin 4142bcd 5075a 4064abcd 3026a 4134ab 4180a 3717bcd 2655ab 3865a 26.93 horizon 4413ab 3929cd 4198abc 2900ab 4235a 3815ab 4913a 2831a 3904a 28.21 kangaroo 2906e 4232abcd 4487ab 2677abcd 2895cdef 3011bcd 3465bcd 2757ab 3307bcde 8.60 local 4095bcd 3664d 3780bcdef 2420bcd 2795def 3717abc 1401e 2537abc 3045e – noble-2 4191bc 4409abcd 4555a 2612abcd 3318cdef 3956a 4167ab 2774a 3748ab 23.09 oa600-32 4975a 4216abcd 3201ef 2162d 2527f 3531abc 2879d 2545abc 3255cde 6.90 oa602-4 4263bc 4664abc 3756bcdef 2991ab 3372bcde 4162a 3070d 2902a 3647abc 19.77 push hybrid-g 4245bc 3579d 4032abcde 2206cd 2737ef 4228a 4115abc 2061c 3401bcde 11.69 souris 4053bcd 3907cd 4403ab 2841ab 3290cdef 4011a 3656bcd 2615ab 3598abcd 18.16 tam 0-397 4079bcd 4196abcd 3503cdef 2757abc 3567abcd 3768ab 3376bcd 2975a 3528abcde 15.86 ufrgs930605 3473de 4208abcd 3892abcde 2671abcd 2693ef 3361abcd 4362ab 2912a 3447bcde 13.20 mean 4160 4230 3880 2650 3290 3660 3620 2660 3520 cv(%) 10.1 12.9 11.8 12.9 14.3 14.4 16.4 11.1 13.6 lsd(5%) 710 912 770 579 796 884 994 497 769 misganaw et al. east african journal of sciences volume 14 (2) 111-120 116 3.3. ammi and gge biplot analysis of grain yield of oat genotypes the oat genotypes gem (g3), local (g7), pusa hybrid g (g11) and oa602-4 (g10) of the grain yield performance were weakly influenced by environmental factors (lower interaction effects). the genotypes kangaroo (g6), oa600-32 (g),chaps (g1), florida501 (g2), goslin (g4), horizon (g5), noble-2 (g8), souris (g12), tam 0-397 (13) and ufrgs930605 (g14) of gain yield performance were strongly affected by environmental factors(higher interaction effects) as showed in figure 1. however, the genotypes were less sensitive to environmental factors may not be higher in grain yield response. as crossa (1990), zobel et al. (1988) and voltas (2002) reported that genotypes near the origin/center of the biplot are not sensitive to environmental interaction, whereas genotypes distant from the origin of the biplot are sensitive and have large interaction effects. in addition, according to yan et al. (2000) ideal genotypes are those having large pc1 scores (wider in adaptable) and small absolute pc2 scores (high stability). in figure 1, the environments adet and fajie followed by sekela were discriminated the genotypes grain yield performance than farta, banja, sekota, sinan and geregera. as akter et al. (2014) report environments with short spokes exert small interactive forces, whereas environments with long spokes exert strong interaction on the performance of oat genotypes. among oat genotypes, goslin (g4) was ideal which was nearest to the concentric circle of the biplot. in addition to g4, the genotypes g10, g5, g13, g8, g2, g1, g12 and g14 which were more adaptable and stable across the tested environments. while the genotypes g11, g9, g7, g3 and g6 were far from the concentric circle of biplot compared to the ideal genotype goslin (figure 2). the genotypes closest to the ideal genotype drawn on the center of concentric and/or average environmental coordinate (aec) are highest yielder (zerihun, 2011 and yan et al., 2002). in the consideration of ammi and gge biplot analysis of oat genotype based on the grain yield performance, genotypes g4, g5, g10, g2, g13, g8 and g12 showed higher interaction to the environmental factors and also higher in grain yielding than the remaining tested oat genotypes across the tested environments. therefore, these genotypes are relatively wider in adaption across the tested environments. figure 1. graphics of ammi biplot of grain yield of oat genotypes using symmetrical scaling of both genotypes and environments (e1=adet,e2 = farta, e3 = sekela, e4 = banja, e5 = sekota, e6 = sinan, e7 = fajie, e8 = geregera, g1 = chaps, g2 = florida501, g3 = gem, g4 = goslin, g5 = horizon, g6 = kangaroo, g7 = local, g8 = noble-2, g9 = oa600-32, g10 = oa602-4, g11 = pusa hybrid g, g12 = souris, g13 = tam 0-397, g14 = ufrgs930605, ipca = interaction principal component axis and agy = adjusted grain yield). misganaw et al. adaptation of food oat genotypes 117 figure 2. graphics of gge biplot of grain yield of oat genotypes using comparison biplot, genotype method and scaling (e1 = adet, e2 = farta, e3 = sekela, e4 = banja, e5 = sekota, e6 = sinan, e7 = faji, e8 = geregera, g1 = chaps, g2 = florida501, g3 = gem, g4 = goslin, g5 = horizon, g6 = kangaroo, g7 = local, g8 = noble-2, g9 = oa600-32, g10 = oa602-4, g11= pusa hybrid g, g12 = souris, g13 = tam 0-397, g14 = ufrgs930605, pc = principal component and aec = average environmental coordinate). 3.3. disease severity and reaction of food oat genotypes the food oat diseases such as scald, net blotch and rust (stem and crown) were recorded according to cob modified scoring method. the oat genotypic responses were resistant to scald and net blotch except horizon (84) which is categorized under moderately resistant. the response of the genotypes to stem and crown rusts were varied in severity scores (0-90%) and their reaction. among 14 tested oat genotypes g3, g4, g9, g10, g12, g13 and g14 were resistant to stem rust whereas g6 was moderately resistant and genotypesg1, g2, g5, g7, g8, and g11 were susceptible to stem rust. on the other hand, genotypes g1, g2, g3, g4, g5, g6, g8, g12 and g14 were resistant to crown rust while genotypes g7, g9, g10, g11 and g13 were susceptible to crown rust (table 7). the studies illustrated that oat rusts, blotch and scald could cause economical yield losses when the oat genotypes are susceptible to oat diseases (paul, 2019 and bowen et al., 2016). misganaw et al. east african journal of sciences volume 14 (2) 111-120 118 table 7. diseases severity and reactions of food oat genotypes. genotype disease severity and reaction scald (1-5) net blotch (00-99) cr sr chaps(g1) 1 r r 60s florida501(g2) 1 r r 90s gem(g3) 1 r r trr goslin(g4) 1 82 r r horizon(g5) 1 84 r r kangaroo(g6) 1 r r 10mr local(g7) 1 r 85s 80s noble-2(g8) 1 r r 60s oa600-32(g9) 1 r 20mr trr oa602-4(g10) 1 31 85s r pusahybrid g (g11) 1 r 80s 80s souris(g12) 1 r trr r tam 0-397(g13) 1 r 40ms trr ufrgs930605(g14) 1 r r r note: lr = stem rust; cr = crown rust; trr = trace and resistant; ms = moderately susceptible; mr = moderately resistant; r = resistant and s = susceptible. 4. conclusion the analysis of variance showed significant (p<0.05) differences for grain yield and yield related traits in genotypes, environments and their interactions. the performance of grain yield and yield related traits of food oat genotypes were significantly affected by the main genetic, environmental and genotype by environment interaction effects. the source of variation for grain yield in food oat genotypes accounted by environments, genotype by environment interactions and genotypes were accounts 69.04%, 24.54% and 6.42%, respectively. among 13 introduced food oat genotypes, goslin and souris were wider in adaptation, higher in grain yield and resistant to crown and stem rust which showed 26.93% and 18.16% grain yield advantage over local variety across tested environments. in the study the genotypes horizon, florida501, oa602-4 and naval-2 showed no significant difference with souris in grain yield performance, however susceptible to crown and stem rusts. therefore, oat genotypes goslin and souris should be demonstrated and scaled out in soil acidity problem areas of banja, fajie, farta, geregera, sekela and sinan districts and in areas with similar agroecologies of ethiopia. 5. acknowledgements the authors acknowledge adet agricultural research center, amhara agricultural research institute and dr. higgns project based in ethiopian sustainable food project for the financial aid as well as technical support. the acknowledgment is also extended to all who actively participated in the research work from the beginning to the end. 6. references akter, a., hassen, j.m., kulsum, u.m., islam, m.r., hossain, k. and rahman, m.m. 2014. ammi biplot analysis for stability of grain yield in hybrid rice (oryza sativa l.). journal of rice research, 2(2): 1– 4. amanuel wada, kassa shawle and deribe gemiyo. 2019. biomass yield and nutritional quality of different oat genotypes (avena sativa) grown under irrigation condition in sodo zuriya district, wolaita zone, ethiopia. agricultural research and technology, 20(4): 197–204. atefah zaheri and sohbat bahraminejad. 2012. assessment of drought tolerance in oat (avenasativa) genotypes. annals of biological research, 3 (5): 2194–2201. bowen, k.l., hagen, a.k., pegues, m. and jones, j. 2016. yield losses due to crown rust in winter oat in alabama. plant health research, 17(2): 95–100. butler-stoney, t.r. and valentine, j. 1991. exploitation of the genetic potential of oats for use in feed and human nutrition. home-grown cereals authority, london, uk. pp. 45–56. crossa, j. 1990. statistical analysis of multi-location trials. advances in agronomy, 44: 55–85. dawit abate and mulusew fikere. 2017. performance of fodder oat (avena sativa l.) genotypes for yield and yield attributes in the highland of bale. journal of biology, agriculture and healthcare, 7(19): 29–33. doehlert, d.c., mcmullen m.s. and hammond j.j. 2001. genotypic and environmental effects on grain yield and quality of oat grown in north dakota. crop science, 41: 1066–1072. faostat. 2018. faostat-crops/ghdx. www.fao.org/faostat/en/#data/qc. accessed on october, 2019). foy, c.d. and murray, j.j. 1998. developing aluminiumtolerant strains of tall fescue for acid soils. journal of plant nutrition, 21(13): 1–25. hoffmann, l.a. 1995. world production and use of oats. pp. 34–61. in: welch, r.w. 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(eds.). barley science: recent advances from molecular biology to agronomy of yield and quality. the harworth press inc., new york. yan, w., hunt, l.a., sheng, q. and szlavnics, z. 2000. cultivar evaluation and mega-environment investigation based on the gge biplot. crop science, 40: 597–605. yan, w. and rajcan, i. 2002. biplot analysis of test sites and trait relations of soybean in ontario. crop science, 42: 11–20. yasemin, h., rukiye, k. and tevrican, d. 2012. evaluation of oat (avena sativa l.) genotypes for grain yield and physiological traits. agriculture, 99(1): 55–60. zerihun, j. 2011. gge-biplot analysis of multienvironment yield trials of barley (hordeium vulgare l.) genotypes in southeastern ethiopia highlands. international journal of plant breeding and genetics, 5(1): 59–75. zobel, r.w., wright, m.j and gauch, h.g. 1988. statistical analysis of a yield trial. agronomy journal, 80: 388–393. misganaw et al. east african journal of sciences volume 14 (2) 111-120 120 ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (2) 99-110 licensed under a creative commons *corresponding author. e-mail: olyaderba@gmail.com attribution-noncommercial 4.0 international license. evaluating rumen fluid-inoculated lignocellulosic substrates for biogas production yimeslal atnafu sema, olyad erba urgessa*, and ameha kebede ayele school of biological sciences and biotechnology, haramaya university, p.o. box 138, dire dawa, ethiopia abstract background: the continuous decline in reserves of fossil and petroleum-based fuel and its undesirable environmental effects is a major problem faced by humanity. biofuel production from lignocellulosic biomass such as agricultural, forest and crop residues, food waste and energy grasses is cost effective and could provide a sustainable solution to the problem. however, since a lignocellulosic substrate is recalcitrant, the choice of more effective digestion inoculums is crucial to achieve an improvement in the efficiency of digesting the substrate. microbial community present in rumen is efficient in hydrolysis of complex organics at mesophilic temperature. objective: the objective of this study was to evaluate and compare biogas production potential of watercrown, potato peel, wheat and sorghum straw and sugarcane bagasse separately inoculated with rumen fluid of cow, goat and sheep. material and methods: total solid, volatile solid, c/n ratio and ph of the slurry before and after anaerobic digestion were determined following standard procedures. the volume of biogas produced was measured using water displacement method for 32 days and energy was estimated from a general methane composition of biogas and 1 m3 of methane contains 34 mj of energy. results: the initial c/n ratio of slurries of potato peel ranged from 15.33 to 16.33. the highest cumulative biogas yield of 1318.83 ml g-1 vsadded-1 was obtained from potato peel inoculated with cattle rumen fluid. the cumulative biogas yield of watercrown inoculated with cattle and sheep rumen fluid was higher than that of all the slurries of sugarcane bagasse and wheat straw. conclusions and implications: slurries of potato peel and watercrown grass produced the highest amount of biogas and could be used potentially for biogas production at the pilot scale. keywords: anaerobic digestion; biomass; cumulative biogas; watercrown 1. introduction the increasing energy requirements along with the consequences of climate change, and depletion of unsustainable and polluting fossil fuels have driven the search for renewable energy sources (cesaro and belgiorno, 2015; zhanga et al., 2019). biomass is a renewable energy source that has potential for conversion into bioenergy via fermentation and anaerobic digestion (cesaro and belgiorno, 2015). biofuel production from abundant and readily accessible resources such as lignocellulosic biomass (agricultural residues, forest residues, and crop residues) is cost effective and is a sustainable solution to the continuous decline in reserves of existing fossil and petroleum-based fuel, undesirable environmental effects, and associated unfavorable prices (saratale and oh, 2012). in biofuel production, a priority research area is looking for alternatives to conventional energy crops (zhang et al., 2019). a promising alternative source is the agricultural sector which generates natural wastes such as manure and arable by-products that could be used for renewable energy generation by anaerobic digestion (spence et al., 2019). grasses are potential alternative source of renewable energy due to their fast growing rate even in infertile land, low cultivation costs, high accessibility, consumption of whole plants and lower environmental impacts when compared to other plants (pantawong et al., 2015). perennial grasses, especially c4 grasses, are excellent substrate for renewable energy production because of a high potential of dry matter yields and fast growth compared to annual crops (karp and shield, 2008). watercrown (pa s pa l i d i u m g e m i n a t u m ) is aquatic, herbaceous and perennial grass. it can become locally abundant under extended warm season flooding (cabi, 2014). growing tips and stem fragments of watercrown for lake restoration is an environmentally and economically useful way of obtaining biomass for biogas production (mallison et al., 2006). harvesting stem fragments of watercrown has a minimal, short term effect on offshore populations and within three weeks, emergent regrowth of the source plants can advance to the status of pre-harvest densities (mallison and thompson, 2010). the choice of more effective digestion inoculums is crucial to achieve the improvement in the anaerobic fermentation efficiency of lignocellulosic substrate (he et al., 2018). ruminants can digest a wide range of cellulosic substrates, including many bioenergy-relevant substrates such as corn, stover, switchgrass and miscanthus (patra and saxena, 2009) because the rumen, as part of the digestive tract in herbivores, houses a mailto:olyaderba@gmail.com yimeslal et al. east african journal of sciences volume 14 (2) 99-110 100 microbial community that naturally and efficiently hydrolyzes cellulose (christopherson and suen, 2013). microbial community present in rumen is efficient in hydrolysis of complex organics at mesophilic temperature. especially, the community present in the fluid of rumen is stable (in terms of production) over time and it is resistant to contamination (weimer, 1996). rumen community of microbes together hydrolyzes and ferment chitin which is the second most abundant organic polymer after cellulose (weimer et al., 2009). the major fermentation products produced by most rumen microorganisms are methane, hydrogen and a diverse set of short-chain fatty acids. these products have potential for use as bioenergy-relevant alternative fuels (weimer, 1996; weimer et al., 2009). several studies were conducted on biogas production from anaerobic digestion of potato peel (liang and mcdonald, 2015; mu et al., 2017; achinas et al., 2019), sugarcane bagasse (janke et al., 2015; adarme et al., 2017; eshore et al., 2017; lima et al., 2018; nostratpour et al., 2018; hashemi et al., 2019; vats et al., 2019), wheat straw (ferraro et al., 2018; he et al., 2018; kong et al., 2018; mancini et al., 2018; moset et al., 2018; kumer et al., 2019; liu et al., 2019), sorghum straw (garcia et al., 2019) and different grass species (mähnert, 2005; uzodinma and ofoefule, 2009). sludge/digestate of anaerobic digestions was used as inoculums in most of these studies. in some, bacteria isolated from bovine rumen (eshore et al., 2017), anaerobic digestate mixed with fresh bovine manure and/or rumen (uzodinma and ofoefule, 2009; lima et al., 2018), cattle rumen fluid (he et al., 2018) and anaerobic fungi isolate (ferraro et al., 2018) were used as inoculums. comparative studies have not yet been done to investigate the potential of inoculums of rumen fluid of cow, goat and sheep for biogas production. furthermore, there is no study conducted on biogas production potential of watercrown. given the effect of feeding pattern of rumen animal on biogas production (uzodinma and ofoefule, 2009) and the synergy of rumen microbe in carrying out food digestion (christopherson and suez, 2013), the effect of agriculturally important rumen animal such as cattle, sheep and goat rumen fluid on biogas production needs to be comparatively investigated. therefore, the overall objective of this study was to evaluate and compare biogas production potential from watercrown with that from well investigated potato peel, sugarcane bagasse, wheat straw and sorghum straw separately inoculated with rumen fluids of cow, goat and sheep. 2. materials and methods 2.1. collection lignocellulosic substrates and inoculum wheat and sorghum straw were collected from haramaya university research farm and sugarcane bagasse was collected from wonji-shewa sugar factory. watercrown (p. geminatum) was collected from marshland around lake denbal (ziway). potato peels were collected from the student cafeteria of haramaya university. the collected lignocellulosic substrates were dried in oven at 60 °c (bozym et al., 2015) until constant weight was obtained. the dried substrates were ground in an electric grinder and the powders were stored in air tight plastic bags at 28 °c (kumer et al., 2019). fresh rumen fluid of cattle, goat, and sheep were collected from haramaya town abattoir under aseptic conditions (begum et al., 2013). the rumen fluids were stored at 6 °c to avoid undesirable fermentation processes (achinas et al., 2019). 2.2. characterization of the slurry in many studies, it is customary to investigate total solid, volatile solid and c/n ratio of the inoculums and substrate, separately. in this study, the slurries were formulated by mixing lignocellulosic substrates with the rumen fluids at 0.1:1 (w/v) ratio that based on study set up for biogas production by achinas et al. (2019). then, the slurries were characterized in terms of their total solid (ts in g), volatile solid (vs in g), c/n ratio and ph. these parameters were measured before and after anaerobic digestion. the amount of ts and vs was determined by modifying methods described by eshore et al. (2017). briefly, the powders of each substrate (5 g) and each inoculum (50 ml) were mixed separately in flask. the slurries were transferred and wrapped up in pre-weighted aluminum foil, and their fresh matter weights (fmw) were measured separately by incubating at 105 °c in a hot air oven till constant weights (dmw) were obtained. these constant dry matter weights (dmw) were ts weight of the slurries and the percentage of the total solid (%ts) was determined as follows: % ts = ts(g) fmw(g) x 100 the obtained total solids were separately transferred to crucible, heated at 500 °c for 2 h in a muffle furnace and their weights were measured. these weights were volatile solid (vs) weight of the slurries and the percentage of the volatile solid (%vs) was determined as follows: % vs = vs(g) ts(g) x 100 c/n ratio was determined by analysis of carbon and nitrogen composition of slurries. the percentage of carbon (%c) found in the slurry samples was determined as described by (shaw, 1959). the percentage of nitrogen (%n) found in the slurry samples was determined as described by (sd, 2003). the measurement of ts, vs and c/n ratio after anaerobic digestions was conducted after decanting overlaying liquid solution found in the anaerobic digesters. yimeslal et al. biogas from lignocellulose digestion using rumen fluid 101 the ph of the slurries before and after the anaerobic digestion was measured using a ph meter (3310, jenway). measurement was conducted following operating procedures of the manufacturer meter manual. the ph meter was warmed up for 15 minutes and its electrode was calibrated before each ph measurements. after calibration, ph was measured by rinsing electrodes with distilled water and submerging it into the slurries. 2.3. anaerobic digestion prior to the anaerobic digestion experiments, each rumen fluid was incubated anaerobically at 37 °c for 5 days (kumer et al., 2019). biogas production was carried out in triplicate using 500 ml plastic bottles as digester. the digestion experiments were carried out in batch mode following the method of achinas et al. (2019). briefly, 10 g of lignocellulosic substrate powder was separately weighed into the digesters. anaerobic digestion was initiated by adding 100 ml rumen fluid in to the digesters. for all experiments, 100 ml of distilled water was added, and no additional nutrients/ trace elements were added to the digesters as it was assumed that they were provided by the inoculums. thereafter, the digesters were sealed using glue and they were incubated at 37 °c for 32 days. the method used to estimate biochemical biogas potential was a volumetric test which considers the amount of displaced liquid as the measurement of biogas produced. for this purpose, 500 ml of plastic bottles were filled with acidified brine solution and were connected to anaerobic digesters. the volume of displaced brine solution was measured every day. 2.4. biogas conversion to energy energy was estimated from the produced cumulative biogas from a general %65 methane composition of biogas and 1 m3 of methane contains 34 mj of energy (irena, 2016). 1 m3 of biogas = 22 mj of energy 2.5. statistical data analysis statistics package for social sciences (spss) version 20 was used to carry out the analysis of total solid (%), volatile solid (%), c/n ratio (%), ph (change) and cumulative biogas yield. microsoft excels 2007 used to carry out analysis of daily biogas yield and rate. during spss operation, paired sample t-test was used to compare percentage of total solid, volatile solid and c/n ratio at the beginning and at the end of anaerobic digestion and single-factor analysis of variances (anova) was used to compare cumulative biogas yield. the means were separated using duncan. statistical significance was established at p-value < 0.05 level. 3. results and discussion 3.1. characterization of the slurry for potato peel inoculated with cattle rumen fluid (ppcrf), the volatile solid (%) after anaerobic digestion was significantly less than volatile solid (%) before anaerobic digestion (table 1). this might be one of the factors that contributed to the highest cumulative biogas production from ppcrf as compared to other slurries. in line with this, a previous study showed as volatile solid (%) removal was increased, cumulative biogas yield was also increased (achinas et al., 2019). in fact, volatile solid content is the proportion of the solid material that can be digested by the micro-organisms and turned into biogas in the digester (irena, 2016). another important factor that affects biogas production is c/n ratio. initial c/n rations of potato peel slurries were lower than that of other slurries. for potato peel slurries, values found (15.33 ± 0.48, 16.73 ± 0.97 and 14.26 ± 0.76 for ppcrf, ppgrf and ppsrf, respectively) were lower than the optimum value recommended for biogas production (20–30: 1) (pontoni et al., 2015; ajeej et al., 2016; perazzolo et al., 2016; achinas et al., 2019). too high or low ratios as compared to the recommended one lead to process inhibition through surplus nitrogen conversion into free ammonia (brc, 2014). as a remedy to inhibition caused by toxic levels of ammonia, stripping off ammonia as a measure to overcome too high levels and adjusting ph by addition acid shifting the nh3/nh4+ balance in the system towards less free ammonia were suggested (brc, 2014). for sugarcane bagasse, watercrown, and wheat straw slurries, the initial c/n ratios were beyond the optimum level. from the c/n ratios of these slurries, higher carbon content is clearly noted. however, these lignocellulosic substrates relatively produced lower biogas as compared to potato peel slurries that might occur due to bioavailability of not all of the carbon content in the substrate for anaerobic digestion. a previous study showed a c/n ratio close to 15–30 for almost all of the investigated lignocellulosic substrate (garcia et al., 2019). eshore et al. (2017) reported 90.8 ± 0.60% ts, 80.48 ± 0.78% vs for sugarcane bagasse. janke et al. (2015) reported extremely higher c:n ratio (116:1) than that of sugarcane bagasse slurries found in this study (44.78 ± 1.53, 39.11 ± 0.25 and 32.55 ± 1.51 for sbcrf, sbgrf and sbsrf, respectively). the difference was that the measured c/n ratios in this study were for slurries (blend of sugarcane bagasse and rumen fluid). the added rumen fluid might have a reduced c/n value. uzodinma and ofoefule (2009) reported 89.80% ts, 75.85% vs and 28.29 c/n ratio for panicum maximum blended with cow manure. the related substrate watercrown (p. geminatum) blended with rumen fluid in this study showed lower %ts and %vs, and higher c:n ratio. yimeslal et al. east african journal of sciences volume 14 (2) 99-110 102 table 1. characteristics of slurry used in batch anaerobic digestion. slurry total solid (%fm) volatile solid (%ts) c/n before after before after before after ppcrf 45.40±2.40a 43.02±1.92b 43.95±2.40a 41.57±1.92b 15.33±0.48a 11.69±1.07b ppgrf 44.27±4.16a 43.52±4.85a 42.82±4.16a 42.07±4.85a 16.73±0.97a 11.49±2.18b ppsrf 46.33±1.22a 44.47±4.79a 44.88±1.22a 43.02±4.79a 14.26±0.76a 9.807±0.71b sbcrf 94.36±1.30a 85.24±1.51b 92.86±1.30a 83.74±1.51b 44.78±1.53a 42.00±8.28a sbgrf 94.28±1.22a 87.38±1.56b 92.28±1.22a 85.38±1.56b 39.11±0.25a 30.95±1.65b sbsrf 95.70±1.86a 87.05±0.81b 93.20±1.86a 84.55±0.81a 32.55±1.51a 32.19±0.60a wccrf 66.44±1.81a 62.38±1.04a 62.60±1.81a 58.54±1.04b 46.22±1.13a 37.59±2.19b wcgrf 65.33±0.88a 61.15±1.24b 61.49±0.88a 57.31±1.24b 38.67±0.70a 37.28±2.79a wcsrf 66.97±1.6a 63.17±1.11b 63.13±1.61a 59.33±1.11b 40.14±0.20a 30.87±0.21b wscrf 95.25±1.32a 87.80±2.92b 92.25±1.32a 84.80±2.92b 40.14±2.72a 33.89±3.20b wsgrf 91.37±3.47a 79.04±1.12b 87.47±3.47a 75.14±1.12b 33.89±2.41a 33.15±1.30a wssrf 85.56±2.03a 79.25±4.45a 80.76±2.03a 74.45±4.45a 44.33±1.16a 38.79±0.71b note: ppcrf, ppgrf and ppsrf are slurries of potato peel and cow, goat and sheep rumen fluid mixture, respectively; sbcrf, sbgrf and sbsrf are slurries of sugarcane bagasse and cow, goat and sheep rumen fluid mixture, respectively; wccrf, wcgrf and wcsrf are slurries of watercrown and cow, goat and sheep rumen fluid mixture, respectively; wscrf, wsgrf and wssrf are slurries of wheat straw and cow, goat and sheep rumen fluid mixture, respectively. letters compare means across row within characteristics of the slurries. different letters show significant difference at p < 0.05. 3.2. ph of the slurry the initial ph was found to range from 6.53 to 8.75. the initial ph for potato peel slurries were 7.24, 6.86 and 6.53 for ppcrf, ppgrf and ppsrf, respectively (figure 1). the maximum daily biogas yield was achieved in a shorter retention time for potato peel slurries than for the other lignocellulosic slurries (figure 3, 4 and 5). this might be due to relatively lower ph values of potato peel slurries. the shorter retention time is needed for digestion of lignocellulosic substrate as the ph of the anaerobic digestion medium closer to the optimum ph. consistent with this suggestion, lan et al. (2013) showed that a ph between 5.2 and 6.2 was needed to obtain maximal hydrolysis of lignocelluloses. uzodinma and ofoefule (2009) recorded ph 7 for grass field (p. maximum) blended with cow dung at charging. in the present study, ph 8.69 was recorded initially for related slurry (wccrf). the final ph ranged from 5.54 to 8.24 (figure 1). the initial ph values of wssrf (8.62), wccrf (8.69) and wscrf (8.75) were beyond the range 6.5 to 8.5 in which methane fermentation took place in anaerobic digestion systems (achinas et al., 2019). after the anaerobic digestion, ph of all the slurries was within the range, except the ph of ppsrf. it was reported that the ph less than 6.5 inhibited the growth of methanogenic bacteria and that subsequently the volume of produced biogas was reduced (food technology et al., 2016; achinas et al., 2019). in contrast to this result, the ph of ppsrf fell below the range from 6.53 to 5.54 after anaerobic digestion and it produced a higher cumulative biogas compared to ppgrf which showed higher value of ph. the lower ph of ppsrf might have reduced the toxic level of nh3. brc (2014) reported that the amount of nh3 present in liquid anaerobic digestion medium is dependent on the total n-nh4+ levels in combination with ph and temperature, i.e. the higher the ph and/or temperature, the more nh3. yimeslal et al. biogas from lignocellulose digestion using rumen fluid 103 figure 1. ph of slurry before and after anaerobic digestion. the effect of change in ph is shown in figure 2. ppcrf showed the lowest change (0.17) and sbgrf showed the highest change (1.02). from the change in ph, it is expected that sbgrf produced the lowest cumulative biogas yield. but, the lowest cumulative biogas yield was obtained from sbcrf (table 2) which showed 0.70 value of change in ph. this showed that the decrease final ph of all slurries resulted in a narrow change in which the activities of natural anaerobic microbes in the slurries were maintained. various research reports have confirmed that the methanogenic microorganisms are highly sensitive to change in ph and survive the ph range of 6.0 to 8.5 i.e. change in ph of 2 (mösche and jördening 1999; wang et al. 1999). the narrow change in ph of the slurries shows strong buffer capacity of lignocellulosic substrates blended with rumen fluid. according to mösche and jördening (1999) and wang et al. (1999), the ph value decreases by accumulation of vfa in the anaerobic digestion process. but, the accumulation of vfa will often not always result in a ph drop due to the buffer capacity of the substrate. for each lignocellulosic substrate, the lower values of changes in ph, the higher cumulative biogas yield. figure 2. the effect of change in ph on cumulative biogas yield. 3.3. biogas production from the slurries experimental data for comparative biogas production of watercrown with other substrates were presented as daily biogas production, daily biogas production rate, cumulative biogas production and energy estimation. 3.3.1. daily biogas production of watercrown compared to potato peel the maximum daily biogas yield achieved in shorter retention time for potato peel slurries as compared to other lignocellulosic slurries. this might be due to 5.00 5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00 p h o f sl u rr y slurry of anaerobic digestion before after yimeslal et al. east african journal of sciences volume 14 (2) 99-110 104 relatively lower initial ph values of potato peel slurries (figure 1). as compared to the slurries of potato peel, all the counterpart slurries of watercrown produced lower maximum daily biogas yield and they took longer period of time to produce the maximum daily biogas yield (figure 3a). for the slurries of potato peel, the maximum daily biogas yield reached 64.33 ml g-1 vsadded-1, 61.95 ml g-1 vsadded-1 and 70.67 ml g-1 vsadded-1 on 12 day for ppcrf, ppgrf and ppsrf, respectively. for the slurries of watercrown, the maximum daily biogas yield reached 28.85 ml g-1 vsadded-1, 28.36 ml g-1 vsadded-1 and 33.10 ml g-1 vsadded-1 on 17, 11 and 14 days for wccrf, wcgrf and wcsrf, respectively. all the slurries of watercrown produced lower daily biogas yield rate during the retention time of anaerobic digestion (figure 3b). for the slurries of watercrown, the peak yield rate reached 19.42 ml g-1 vsadded-1 day-1, 17.73 ml g-1 vsadded-1 day-1 and 21.47 ml g-1 vsadded-1 day-1 on 23, 15 and 19 days for wccrf, wcgrf and wcsrf, respectively. for the slurries of potato peel, the peak yield rate reached 47.86 ml g-1 vsadded-1 day-1, 39.28 ml g-1 vsadded-1 day-1 and 49.31 ml g-1 vsadded-1 day-1 on 20, 18 and 19 days for ppcrf, ppgrf and ppsrf, respectively. figure 3. daily biogas production of watercrown slurry compared to potato peel slurry. daily biogas yield (a). daily biogas yield rate (b). ppcrf, ppgrf and ppsrf are slurries of potato peel and cow, goat and sheep rumen fluid mixture, respectively; wccrf, wcgrf and wcsrf are slurries of watercrown and cow, goat and sheep rumen fluid mixture, respectively. 3.3.2. daily biogas production of watercrown compared to sugarcane bagasse compared to the slurries of sugarcane bagasse, slurries of watercrown maintained producing higher daily biogas yield during 1 to 26, 5 to 19 and 6 to 26 retention times for wccrf, wcgrf and wcsrf, respectively (figure 4a). for slurries of sugarcane bagasse, the maximum daily biogas yield reached 12.33 ml g-1 vsadded-1 , 15.82 ml g-1 vsadded-1 and 18.46 ml g-1 vsadded-1 on 25, 20 and 20 days for sbcrf, sbgrf and sbsrf, respectively. the slurries of sugarcane bagasse took longer retention time to reach the highest daily biogas yield and produced lower values of the highest yield. yimeslal et al. biogas from lignocellulose digestion using rumen fluid 105 all the slurries of watercrown produced higher daily biogas yield rate starting from 7-day retention time of anaerobic digestion. wccrf produced higher daily biogas yield rate than that of sbcrf during entire retention time. wcgrf produced higher daily biogas yield rate than that of sbgrf starting from 6-day retention time. wcsrf produced higher daily biogas yield rate than that of sbsrf starting from 7-day retention time (figure 4b). for the slurries of sugarcane bagasse, the peak daily biogas yield rate reached 9.50 ml g-1 vsadded-1 day-1, 11.85 ml g-1 vsadded-1 day-1 and 12.33 ml g-1 vsadded-1 day-1 on 27, 25 and 23 days for sbcrf, sbgrf and sbsrf, respectively. the plot of daily biogas yield rate of the two slurries showed different pattern. the plot of slurries of sugarcane bagasse showed more constant pattern. figure 4. daily biogas production of watercrown slurry compared to sugarcane bagasse slurry. daily biogas yield (a). daily biogas yield rate (b). sbcrf, sbgrf and sbsrf are slurries of sugarcane bagasse and cow, goat and sheep rumen fluid mixture, respectively wccrf, wcgrf and wcsrf are slurries of watercrown and cow, goat and sheep rumen fluid mixture, respectively. 3.3.3. daily biogas production of watercrown compared to wheat straw compared to the slurries of wheat straw, slurries of watercrown maintained producing higher daily biogas yield in some period of retention times. wccrf maintained producing higher daily biogas yield than that of wscrf starting from 5-day of retention time. wcgrf maintained producing higher daily biogas yield than that of wsgrf in the 6 to 15 retention times, then after, it maintained producing lower daily biogas yield. wcsrf maintained producing higher daily biogas yield than that of wssrf in the 6 to 22 retention times (figure 5a). for the slurries of wheat straw, the highest daily biogas yield reached 18.44 ml g-1 vsadded-1, 21.60 ml g-1 vsadded-1 and 21.32 ml g-1 vsadded-1 on 21, 25 and 22 days for wscrf, wsgrf and wssrf, respectively. the slurries of wheat straw took longer retention time to reach the highest daily biogas yield and produced lower values of highest daily biogas yield. all the slurries of watercrown produced higher daily biogas yield rate than that of counterpart slurries of wheat straw starting from 5-day retention time of anaerobic digestion. wccrf produced higher daily biogas yield rate than that of wscrf starting from 5-day yimeslal et al. east african journal of sciences volume 14 (2) 99-110 106 retention time. wcgrf produced higher daily biogas yield rate than that of wsgrf and wcsrf produced higher daily biogas yield rate than that of wssrf during entire retention time (figure 5b). for the slurries of wheat straw, the peak daily biogas yield rate reached 13.30 ml g-1 vsadded-1 day-1, 15.63 ml g-1 vsadded-1 day-1 and 13.73 ml g-1 vsadded-1 day-1 on 22, 28 and 22 days for sbcrf, sbgrf and sbsrf, respectively. the plot of daily biogas yield rate of the two slurries showed different pattern. figure 5. daily biogas production of watercrown slurry compared to wheat straw slurry. daily biogas yield (a). daily biogas yield rate (b). wscrf, wsgrf and wssrf are slurries of wheat straw and cow, goat and sheep rumen fluid mixture, respectively; wccrf, wcgrf and wcsrf are slurries of watercrown and cow, goat and sheep rumen fluid mixture, respectively. 3.3.4. cumulative biogas production and energy conversion the cumulative biogas yield (ml g-1 vsadded-1) from anaerobic digestion of potato peel, sugarcane bagasse, watercrown and wheat straw inoculated with rumen fluid of cow, goat and sheep were shown in table 2. after 32 days, the highest cumulative biogas yield (1318.83 ml g-1 vsadded-1) was obtained from ppcrf and the lowest cumulative biogas yield (286 ml g-1 vsadded-1) was obtained from sbcrf. the highest cumulative biogas production of slurries of potato peel was might be attributed to c/n ratio close to optimum range and significant removal of percent of volatile solid (table 1). the cumulative biogas yield of wccrf (541.03 ml g1 vsadded-1) and wcsrf (547.75 ml g-1 vsadded-1) were higher than that of all the slurries of sugarcane bagasse and wheat straw. this might be due to a higher lignin percentage in sugarcane bagasse and wheat straw. a review conducted by cesario and bolgia (2015) showed 20% lignin content in bagasse and 8.3 to 24% lignin content in wheat straw. uzodinma and ofoefule (2009) yimeslal et al. biogas from lignocellulose digestion using rumen fluid 107 reported the cumulative gas yield of 225.80 l per total mass of slurry from anaerobic digestion of panicum maximum blended with cow dung for 30 days. inoculums significantly affected cumulative biogas yield of potato peel, sugarcane bagasse, watercrown and wheat straw (p < 0.05) (table 2). ppgrf produced significantly the lowest cumulative biogas yield. the order of cumulative biogas yield was ppcrf > ppsrf > ppgrf. for sugarcane bagasse, sbsrf produced significantly the lowest cumulative biogas yield and the cumulative yield order was sbsrf > sbgrf > sbsrf. for watercrown anaerobic digestion, wcgrf produced significantly the lowest cumulative biogas yield and the order was wcsrf > wccrf > wcgrf. for wheat straw anaerobic digestion, wsgrf produced significantly the highest cumulative biogas yield and the order was wsgrf > wscrf > wssrf. the result showed variation of cumulative biogas production based on inoculums and the type of substrates. these variations were might be due to the difference in feeding habit of cow, goat and sheep. the direct influence of diet on the ruminal microbial community was previously reported indicating that particular groups of microbes are better adapted for fermentation of specific feedstocks (patra and saxena, 2009). according to christopher and suez (2013), it is practical to feed ruminant animals a preferred substrate and screen a stable microbial consortium that is well adapted to the fermentation of the feed. biogas production is usually measured or estimated in cubic meters over a period of time, but it should be converted and reported in energy units (irena, 2016). accordingly, the cumulative biogas produced was converted to energy unit and result was included in table 2. ppcrf produced the highest cumulative ch4 (857.35 ± 20.18 ml g-1 vsadded-1) with total energy estimation of 29.15 ± 0.69 mj. whereas, sbcrf produced the lowest cumulative ch4 (185.90 ± 3.25 ml g-1 vsadded-1) with total energy estimation of 6.32 ± 0.11 mj. table 2. cumulative biogas production of the slurries and energy estimation. slurry cumulative biogas yield (ml g-1 vsadded-1) cumulative ch4 (ml g-1 vsadded-1) total energy estimation (mj) ppcrf 1318.83±31.31g 857.35 ± 20.18g 29.15 ± 0.69g ppgrf 997.73 ± 17.84f 648.48 ± 11.41f 22.05 ± 0.39f ppsrf 1311.94 ± 7.13g 852.80 ± 4.55g 29.00 ± 0.16g sbcrf 286.00 ± 5.21a 185.90 ± 3.25a 6.32 ± 0.11a sbgrf 334.33 ± 1.31b 217.32 ± 0.75b 7.39 ± 0.02b sbsrf 339.70 ± 2.06b 221.00 ± 1.30b 7.51 ± 0.05b wccrf 541.03 ± 10.77e 351.65 ± 7.03e 11.96 ±0.24e wcgrf 397.43 ± 6.37c 258.48 ± 4.18c 8.79 ± 0.14c wcsrf 547.75 ± 5.12e 356.20 ± 3.38e 12.11 ± 0.12e wscrf 387.15 ± 4.26c 251.77 ± 2.63c 8.56 ± 0.09c wsgrf 483.33 ± 15.10d 314.17 ± 9.78d 10.68 ± 0.33d wssrf 381.45 ± 5.20c 247.87 ± 3.58c 8.43 ± 0.12c note: letters compare means across column. different letters show significant difference at p < 0.05. 4. conclusions this study revealed that the use of rumen fluid resulted in fast degradation of lignocellulosic substrate. potato peel slurries produced the highest cumulative biogas yield in a relatively short period of time. therefore, it is economical and environmentally friendly to use potato peel waste from domestic and food processing industries for fast and potential biogas production contributing to the solid waste management. the results demonstrate that the second highest biogas yield was obtained from watercrown slurry. since watercrown is fast-growing, high-yielding, available substrate in plenty, it can be used for sustainable biogas production. nutrient composition of watercrown slurry should be determined for its application for a large scale biogas production. 5. acknowledgements this paper is part of haramaya university research grant coded hurg-2018-06-01-97. therefore, office of the vice-president for research affairs, haramaya university, deserves gratitude for funding this research project. 6. references achinas, s., li, y., achinas, v. and euverink, g.j.w. 2019. biogas potential from the anaerobic digestion of potato peels: process performance 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and substrate to inoculum ratio. biochemical engineering journal, 143: 91–100. yimeslal et al. east african journal of sciences volume 14 (2) 99-110 110 ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (2) 131-140 licensed under a creative commons *corresponding author. e-mail: yahayatajudeen@gmail.com attribution-noncommercial 4.0 international license. effects of telecommunication mast electromagnetic radiation (emr) on exposed rats (rattus norvegicus) tajudeen yahaya1*, esther oladele2, obaroh israel3, jamilu bala4, abdulhakeem haruna1, and abubakar muhammad1 1 department of biology, federal university birnin kebbi, nigeria 2 biology unit, distance learning institute, university of lagos, nigeria 3 department of animal and environmental biology, kebbi state university of science and technology 4 department of biochemistry and molecular biology, federal university birnin kebbi, nigeria abstract background: the safety of electromagnetic radiation (emr) from modern telecommunication devices is controversial as some studies reported negative effects, while others reported no effects. thus, more studies are necessary to clear the controversy, so as to design appropriate precautionary and palliative measures if found toxic. objective: this study was conducted to determine the effects of telecommunication mast emr on selected health indices of rats (rattus norvegicus). materials and methods: twenty-four (24) rats were divided into two groups of 12 rats each. group 1 was made the control, while group 2 was exposed to 18000 mhz emr at 50 m from a telecommunication mast. the weight, body temperature, reproductive activities, and reactions of the rats were observed for 60 days. thereafter, the rats were sacrificed and their blood parameters, liver function, and histology were examined. results: the exposed rats were less active, weighed and reproduced less, had lower offspring survival rates and insignificantly (p > 0.05) elevated body temperature. the white blood cells (wbc) of the exposed rats were significantly increased (p < 0.05), while the packed cell volume (pcv), hemoglobin (hb), red blood cells (rbc), and lymphocytes were reduced. the aspartate aminotransferase (ast), alkaline phosphatase (alp), alanine aminotransferase (alt), and total protein (tp) of the exposed rats were significantly increased, while the albumin (alb) was significantly reduced. the ovary, lung, and kidney tissues of the exposed rats showed no abnormalities, but necrosis of the hepatocytes and fat were observed in their livers and the skins, respectively. conclusion and recommendation: it is concluded that electromagnetic radiation (emr) from modern telecommunication devices harmed the health of exposed rats. it is inferred from the results that emr has negative effects on the health of mammals. hence, it is advisable not to site telecommunication masts close to dwelling places. keywords: emr; lymphocytes; necrosis; pcv; rat; telecommunication mast 1. introduction electromagnetic radiation (emr) is widely used in modern technologies. however, some of these devices may emit emr strong enough to induce toxicity in biological systems, thus necessitating their safety evaluation. emr is an energy that moves in waves and takes many forms, such as radio waves, microwaves, heat waves, ultraviolet light, infrared light, x-rays, and gamma rays (jim, 2015). among the emr forms, gamma rays have the shortest wavelength, being less than a nanometer, while radio waves have the longest wavelength, being more than a nanometer (jim, 2015). the length of the wavelength is inversely proportional to the amount of energy. thus, short-wavelength radiations have more energy than long-wavelengths (cleaver et al., 2010). as such, gamma rays, x-rays, and some ultraviolet waves with short wavelengths have a high amount of energy and frequency to knock out electrons from atoms and are termed ionizing emr (nagaraja, 2019). emr such as radio waves, microwaves and heat waves have a long wavelength which results in low frequency and energy and are termed non-ionizing emr (who, 2019). acute exposures to ionizing emr can cause skin burns or radiation syndrome, while prolonged exposures may cause chronic diseases (who, 2018). these chronic diseases include cancers, mental disorders, neurologic illnesses, fetal abnormalities, cardiovascular diseases, sleep disorders, etc. (naeem, 2014; batool et al., 2019). a non-ionizing emr can set an atom in motion but does not have enough energy to remove or alter it (usepa, 2019). however, long-term exposure to large amounts of non-ionizing emr may result in heat-related health hazards such as skin burns, yahaya et al. east african journal of sciences volume 14 (2) 131-140 132 premature aging of the skin, eye damage, and skin cancer (cdc, 2015). however, controlled emr can be used in the hospital to treat diseases, especially to destroy cancer cells (nagaraja, 2019). emr is also used in academics, industry, agriculture, archaeology (carbon dating), space exploration, law enforcement, geology (e.g. mining), as well as for generating electricity, among others (usnrc, 2017). additionally, emr is used in modern technologies such as mobile phones, wi-fi, computer, and television. electromagnetic radiations have numerous sources, which are classified into natural and man-made (acs, 2019). natural sources include cosmic microwaves, infrared light, visible light, among others, while artificial sources include light bulbs, gas discharge lamps, x-ray machines, lasers, radiotherapy equipment, nuclear facilities, etc. (julie et al., 2014; panagopoulos et al., 2015). modern telecommunication facilities, particularly telecommunication masts, mobile phones, among others, are some recent additions to the list of suspected emr sources (olatunde et al., 2011). modern telecommunication devices have helped revolutionize communication and formed part of human socioeconomic life. however, there is a controversy surrounding the safety of the emr from mobile phone devices. while some studies like al-glaib et al. (2008) and el-bediwi et al. (2011) linked mobile phone emr to health hazards, some others like keykhosravi et al. (2018) and usfg (2020) found no link. thus, more studies are needed to clear the controversy, so as to design appropriate precautionary and palliative measures if found toxic. to this end, this study assessed the effects of telecommunication mast emr on some exposed rats in kalgo, kebbi state, nigeria. 2. materials and methods 2.1. description of study area the study was carried out in kalgo, northwestern, nigeria. kalgo is about 15 km from birnin kebbi, the capital city of kebbi state. kalgo is a nodal town, along the intersection of birnin kebbi-jega road and birnin kebbi-bunza road on latitude 12o27'57.8808' north and longitude 4o11'58.2864' east (figure 1). it has a telecommunication mast density of at least 20, most of which are located in residential areas. kebbi state is bordered by sokoto state in the north, niger state in the south, katsina and zamfara state in the east as well as niger and benin republic in the west. as of 2006, at least 3,256,541 people lived in the state (population council, 2007), mostly artisans and farmers. the natural vegetation of the state comprises a mixture of sudan and guinea savannah. however, long-term anthropogenic activities have changed the natural vegetation of the state to mainly sudan savannah vegetation. the climate of the state is characterized by a long dry season and short wet season with an annual rainfall of about 787 mm (yahaya et al., 2020). the temperature could fall below 20 oc and rise above 40 oc. figure 1. locations of kalgo, kebbi state, nigeria (arcgis 10.3 software). yahaya et al. effects of telecommunication mast emr 133 2.2. sources of animal samples and management the study was approved and conducted according to the guidelines set by the animal ethics committee of federal university birnin kebbi, nigeria. twenty-four (24) mixed-sex rats (rattus norvegicus), aged 50 days and mean weight 201 ± 11 g were sourced from the department of biology, federal university birnin kebbi in december 2019. the rats were managed in well-ventilated metal cages, under ambient conditions with a 12h light/dark cycle. the rats were allowed to acclimatize to the environment for 14 days before commencing the study. water and pellet feeds purchased from the vital feed industry, lagos, nigeria, were fed to the rats ad libitum. 2.3. study design the rats were divided into two groups of 12 rats each (6 males and 6 females), of which group one was made the control and placed away (at about 1 km) from all sources of emr. group 2 was exposed to 18000 mhz emr at about 50 m from a telecommunication mast (aderoju et al., 2014). the weight, reproductive activities, body temperature, and reactions of the rats were observed daily for 60 days, after which the rats were sacrificed by cervical dislocation. blood samples were taken for hematological and liver function tests and the livers, lungs, kidneys, skins and ovaries were obtained for histopathological examination. 2.4. procedure for blood collection each rat was held firmly while its tail was swapped with alcohol to disinfect the tail veins. the veins were then pierced with a 5 ml syringe, 20 gauge needle, and about 2.5 ml of blood was drawn slowly and transferred to bottles containing disodium ethylenediaminetetraacetic acid (na2edta). 2.5. measurement of emr, body temperature, weight, and reactions the emr around the telecommunication mast was measured using a trifield emr meter (model tf2) and the body temperature was measured by inserting a clinical thermometer into the rectal cavity of the rats. the weight was measured using an electronic weighing balance, while the rats’ reactions were scored very active, active, or not active based on the interactions with other rats, feed intake, and mobility. 2.6. hematological tests 2.6.1. determination of packed cell volume (pcv) the pcv was determined using the micro-hematocrit centrifuge method described by bull and hay (2001). two-third of a capillary tube was filled with each of the blood samples and one end of the tube was sealed using a bunsen burner flame to prevent leakage, before and during spinning in the hematocrit centrifuge machine. the capillary tubes were labeled, arranged in the micro-hematocrit centrifuge machine, and centrifuged at 12,000 rpm for five minutes. the centrifugation separated the blood plasma from the red blood cells in the tubes, which was then measured using a micro-hematocrit reader. 2.6.2. determination of hemoglobin (hb) the hb content was measured using the cyanmethemoglobin method as described by hope et al. (2019). about 0.02 ml of blood was transferred into a test tube containing 5 ml drabkin’s reagent. the solution was mixed thoroughly and allowed to stand for 10 minutes at 250 °c to allow cyan-methemoglobin to form. the mixture was then transferred into a cuvette and read on a spectrophotometer at a wavelength of 540 nm. the reading recorded was compared with a pre-calibrated chart to obtain the actual hb values in g dl-1. 2.6.3. determination of white (wbc) and red blood cells (rbc) the wbc and rbc were estimated using the improved neubauer hemocytometer as described by cheekurthy (2019). the blood samples were diluted at a ratio of 1:200 with ammonium oxalate and hayem’s solution and added to the hemocytometer chamber. the wbc being bigger was counted from the four corner squares of the chamber. to estimate the rbc, the small squares in the middle of the chamber were zoomed, and the rbc counted. 2.6.4. determination of lymphocytes the lymphocytes were estimated as described by heather and tim (2016). a drop of each blood sample was smeared on a clean glass slide and stained with a wright-giemsa dye, which helped differentiate the subtypes of the wbc in the sample. the number of lymphocyte cells was then calculated using an automated blood count machine. 2.7. liver function tests the liver function tests were performed from the blood serum, which was prepared as described by henry (1979). blood samples in covered test tubes were allowed to clot by leaving it undisturbed at room temperature for about 30 minutes. the clots were then removed by centrifuging between 1000 and 2000 x g for 10 minutes in a refrigerated centrifuge. the resulting supernatant (serum) was immediately transferred into a clean polypropylene tube using a pasteur pipette and then used to determine the liver enzymes and proteins outlined below. 2.7.1. determination of alanine aminotransferase (alt) the alt activity was estimated by colorimetric method described by mirmiran et al. (2019). a reagent, 2, 4 dinitrophenyl hydrazine was added to the blood serum, producing pyruvate hydrazine. the alt was yahaya et al. east african journal of sciences volume 14 (2) 131-140 134 measured using a cobas mira plus cc chemistry analyzer (switzerland) based on the colorimetric measurement of pyruvate hydrazine formed. 2.7.2. determination of aspartate aminotransferase (ast) the same colorimetric method used to determine the alt activity was also used for the ast. however, the reagent, 2, 4 dinitrophenyl hydrazine was replaced with 2, 4 nitrophenyl hydrazine, producing oxaloacetate hydrazine. the colorimetric measurement of the oxaloacetate hydrazine concentration was used to estimate the ast activity. 2.7.3. determination of alkaline phosphatase (alp) the alp activity was determined using the spectrophotometric method described by bergmeyer and bernt (1974). about 0.02 ml of the blood serum was added to 1.0 ml diethanolamine buffer, ph 9.9, magnesium chloride (mgcl2), and a substrate, pnitrophenyl phosphate. the mixture produced was stirred, and the absorbance was taken over 1, 2 and 3 minutes using a timer at 405 nm in a spectrophotometer. change in absorbance taken after 2 and 3 minutes was used to determine the final absorbance of alp. 2.7.4. determination of total protein (tp) the biuret method described by layne (1957) was used to determine the tp. about 0.02 ml of the blood serum was treated with an equal volume of 1% sodium hydroxide followed by a few drops of aqueous copper (ii) sulfate. the mixture was stirred and incubated for 10 minutes at room temperature, after which the absorbance of the colored solution was read at 546 nm. 2.7.5. determination of albumin (alb) the bichromatic digital endpoint method described by kelly (1979) was used to determine the alb concentrations. about 1.0 ml of bromcresol purple (bcp) was added to 0.02 ml of the blood serum, producing bcp–alb complexes. the change in the absorbance at 600 nm was measured with a spectrophotometer and considered the concentration of alb in the sample. 2.8. evaluation of reproductive performance the reproductive performance of the rats was evaluated from the numbers of the reproductive cycle completed by females in each group and the number of offspring born per birth. the offspring survival rate in each group was also calculated by taking the percentage of the offspring that survived from the total offspring born per female. 2.9. histopathological examination the histopathological examination was carried out as described by tajudeen et al. (2020). about 5 mm thick samples of the selected tissues were preserved in 10% neutral buffered formalin solution to prevent putrefaction and maintain the original structures and shapes of the tissues. the tissues were then dehydrated using increasingly concentrated alcohol (60, 80, and 100%) and then embedded in paraffin wax. the embedded tissues were thereafter sectioned at 5 µm with a rotary microtome (model yr421), spread on glass slides, and air-dried. hematoxylin and eosin dyes were used to stain the slides and viewed under a light microscope for histopathological abnormalities. 2.10. data analysis data were analyzed using the statistical package for social sciences (spss) version 20 for windows. the student’s t-test was used to compare the differences between the test and control groups in which p < 0.05 was considered a significant difference. 3. results and discussion 3.1. effects of the emr on rats’ weight, body temperature and reactions compared with the control, the exposed rats had insignificantly (p > 0.05) elevated body temperature, were less active, and weighed significantly (p < 0.05) less (table 1). an earlier study by wyde et al. (2018) also observed non-significant elevated body temperature in some rats exposed to mobile phone emr. however, forouharmajd et al. (2018) and mai et al. (2020) reported a significantly elevated body temperature in some mice exposed to mobile phones emr. changes in the body temperature could result from an interaction between emr and a primary cold sensor in mammals known as transient receptor potential cation channel subfamily melastatin member 8 (trpm8) receptors (mai et al., 2020). the nonconsistence of the mentioned studies and the present study could be due to the varied distances of the test subjects from the communication gadgets. in a survey conducted by akintonwa et al. (2008), 57.72% of the participants who suffered from emr-related diseases, including increased body temperature lived close to telecommunication masts (less than 50 m). the authors concluded that the hazards of emr from communication devices and facilities are directly proportional to the proximity and duration of exposure. the loss of weight observed in the exposed rats could be a sign of cytotoxic interactions between the emr and the rat cells. according to gye and park (2012), emr exposure may generate free radicals, causing cell growth inhibition, protein misfolding, and dna breaks. earlier studies by aziz et al. (2010) and srivastava et al. (2017) also reported growth retardation among some rats exposed to 900 mhz emr from yahaya et al. effects of telecommunication mast emr 135 mobile phones. however, sani et al. (2018) recorded a weight increase by some rats exposed to low emr from mobile phones, while lee et al. (2004) recorded no weight gain in rats exposed to 60 mhz emr. table 1. weight, body temperature and reactions of rat exposed to telecommunication mast emr. group weight gain (g) average temperature (oc) reaction control 4.10 ± 1.1 32.10 ± 2.2 very active exposed 2.30 ± 0. 8* 33.16 ± 2.4 active note: values were expressed as mean ± sd (n = 12); the value with an asterisk (*) in the column is statistically different from the control at p ≤ 0.05 (student’s t-test). 3.2. effects of the emr on hematological parameters the levels of the wbc of the exposed rats were significantly higher (p < 0.05) than the control, indicating that the body recruited more immune cells to fight the absorbed emr (table 2). adebayo et al. (2019) also observed elevated wbc levels in some rats exposed to 1.40 w cm-2 emr at 24 m from the base of telecommunication masts. the authors opined that the elevated wbc levels could be an indicator of selfdefense mechanism against exposure to foreign bodies. in contrast to the wbc, the levels of the pcv, hb, rbc, and lymphocytes of the exposed rats were reduced, but the reduction was significant (p < 0.05) only in the levels of the pcv and lymphocytes. the reduced blood parameters indicate that the rats were anemic, possibly modulated by the reduced activities noticed in the rats, which could have resulted in loss of appetite and fewer feed intakes, culminating in iron deficiency. according to tatala et al. (1998), dietary iron deficiency is a major cause of anemia. the reduction in the blood parameters could also mean the emr induced oxidative damage in the rats’ blood cells. according to adebayo et al. (2019), emr exposure may induce oxidative stress in animal systems, resulting in the reduction of blood parameters. previous studies by singh et al. (2013) and aberumand et al. (2016) also found significant decreases in the levels of hb, rbc, and blood platelets of some mice exposed to mobile phone emr. however, sani et al. (2018) reported an increase in the hb and rbc levels of some rats exposed to emr from mobile phones. table 2. blood parameters of the rats exposed to telecommunication mast emr. parameter control exposed pcv (l l-1) 0.28 ± 0.01 0.26 ± 0.01* hb (g dl-1) 9.43 ± 2.2 8.67 ± 2.0 wbc (mc mm-3) 6.32 ± 1.9 11.36 ± 3.3* rbc (mc mm-3) 5.30 ± 1.0 4.73 ± 1.4 lym (c µl-1) 91.93 ± 2.6 81.03 ± 4.1* note: values were expressed as mean ± sd (n = 12); the values with an asterisk (*) in the row are statistically different from the control at p ≤ 0.05 (student’s t-test); pvc = packed cell volume; hb = hemoglobin; wbc = white blood cells and lym = lymphocytes. 3.3. effects of the emr on liver function enzymes and proteins table 3 compares the effects of the emr on the liver enzymes and proteins of the exposed rats with the control. the tp, ast, alp, and alt of the exposed rats were significantly increased (p < 0.05), while the alb was significantly reduced. these findings agree with el-bediwi et al. (2011) and ghaedi et al. (2013) who observed elevated levels of ast and alt as well as decreased levels of alb in some rats exposed to mobile phone radiation. the increase in the liver enzymes of the rats in the present study could mean a sign of liver damage. according to el-bediwi et al. (2011), the membrane of hepatocytes (liver cells) is highly permeable, so when the liver is injured, the liver enzymes are released into the bloodstream, raising the levels of the enzymes in the blood. the decrease in the alb levels could indicate oxidative stress from the emr, damaging the alb molecules. according to jbireal et al. (2018), emr may generate reactive oxygen species, damaging cellular components such as proteins, lipids and dna. yahaya et al. east african journal of sciences volume 14 (2) 131-140 136 table 3. levels of the liver enzymes and proteins of the rats exposed to telecommunication mast emr. parameter control exposed tp (g l-1) 70.000 ± 0.58 95.00 ± 12.1* alb (g l-1) 40.67 ± 0.88 33.33 ± 0.88* alp (iu l-1) 21.00 ± 0.58 26.67 ± 3.18* ast (iu l-1) 11.67 ± 0.88 21.02 ± 2.01* alt (iu l-1) 13.33 ± 0.67 19.00 ± 2.08* note: values were expressed as mean ± sd (n = 12); the values along the same row with an asterisk (*) are statistically different from the control at p ≤ 0.05 (student’s t-test). 3.4. effects of the emr on reproductive performance table 4 reveals the effects of the emr on the reproductive activities of the rats. while the control rats completed two reproductive cycles during the duration of the experiments, the exposed rats did one cycle. the number of offspring per birth and the offspring survival rates of the control rats were also higher than the exposed rats. these observations showed that the emr reduced the reproductive function of the exposed rats and the survival rates of their offspring. the reduced offspring survival rates could be due to exposure during fetal development and after birth. the reduced reproductive function could result from the reduced activities of the rats, which could have reduced the mating frequency of the rats. the emr could also induce sperm abnormalities in the exposed rats. according to adah et al. (2018) and kesan et al. (2018), emr may induce oxidative stress, causing hormonal, sperm and testicular abnormalities. emr exposure may also affect estrous cycle, pregnancy success, and fetal development (gye and park, 2012). an earlier study by magras and xenos (1997) observed a loss of reproductive function indicated by progressive decrease in the number of newborns in mice exposed to between 168 nw cm-2 and 1053 nw cm-2 rf-emr. table 4. reproductive performance of the rats exposed to telecommunication mast emr. group (n = 12) no of reproductive cycles in 60 days offspring per birth offspring survival rate (%) control 2 12 90.00 exposed 1 8 81.91 3.5. histopathological effects of the emr the effects of the emr on the livers, skins, ovaries, kidneys, and lungs of the exposed rats are shown in plates 1 to 5. while normal hepatocytes were seen in the livers of the control rats (plate 1a), necrosis of the hepatocytes were observed in the livers of the exposed rats (plate 1b). the skins of the control rats (plate 2a) had mild thinning of the epidermis, while fat necrosis was observed in the epidermis of the exposed rats (plate 2b). there were no histological changes in the ovaries of the control and exposed rats as both showed normal ovarian follicles (plates 3 a and b). plates 4 a and b also showed no abnormalities in the kidneys of the control and exposed rats as both groups had normal glomeruli and tubules. similarly, normal alveolar spaces were observed in the lungs of the control and exposed rats (plates 5 a and b). the presence of necrosis in the livers and the skins of the exposed rats proved that the emr was strong enough to induce biological effects, particularly tissue damage. liver and kidney damage in rats exposed to 900 mhz emr were reported by el-bediwi et al. (2011) and deniz et al. (2017). akintonwa et al. (2009) also reported skin irritations among people living near telecommunication masts. emr causes histopathology damage by inducing oxidative stress in the tissues of the exposed organisms, generating free radicals (oktem et al., 2005; kıvrak et al., 2017). the normal histology of the lungs, kidneys, and ovaries of the exposed rats in this study suggests that the livers and the skins are the most affected, or points of the first contact by the emr. these claims are justifiable because the skin is the body’s contact with the environment and the liver is the body’s main detoxifier. the normal histology of the ovary further showed that the reduced reproductive function observed in the exposed rats could have been induced by other factors listed earlier. yahaya et al. effects of telecommunication mast emr 137 [a] [b] plate 1. photomicrographs of the livers of the control rats (a) showing normal hepatocytes and exposed rats (b) showing necrosis of the hepatocytes (x 100). [a] [b] plate 2. photomicrographs of the skin of the control rats (a) showing thinning of the epidermis and exposed rats (b) showing fat necrosis (x 100). [a] [b] plate 3. photomicrographs of the ovaries of the control (a) and exposed rats (b) showing normal ovarian follicle (x 100). [a] [b] plate 4. photomicrographs of the kidneys of the control (a) and exposed rats (b) showing normal glomeruli (long arrows) and tubules (short arrows) (x 100). yahaya et al. east african journal of sciences volume 14 (2) 131-140 138 [a] [b] plate 5. photomicrographs of the lungs of the control (a) and exposed rats (b) showing normal alveolar spaces (x 100). 4. conclusion the results of this study have established that exposure to telecommunication mast emr can induce toxicity in biological systems. in particular, the emr interfered with the functions of the selected health indices of the exposed rats, resulting in reduced reactivity. the exposed rats also weighed less than the control, indicating mitotic cell death or a loss of appetite consequent of the reduced activities. similarly, the blood parameters as well as the liver enzymes and proteins of the exposed rats were altered, suggesting anemia and liver damage, respectively. the presence of necrosis in the livers and the skins 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https://www.fda.gov/radiation-emitting-products/cell-phones/do-cell-phones-pose-health-hazard https://www.fda.gov/radiation-emitting-products/cell-phones/do-cell-phones-pose-health-hazard https://www.fda.gov/radiation-emitting-products/cell-phones/do-cell-phones-pose-health-hazard https://www.nrc.gov/about-nrc/radiation/around-us/uses-radiation.html https://www.nrc.gov/about-nrc/radiation/around-us/uses-radiation.html https://www.who.int/ionizing_radiation/about/what_is_ir/en/ https://www.who.int/ionizing_radiation/about/what_is_ir/en/ ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (1) 39-50 _____________________________________________________________________________________________ licensed under a creative commons *corresponding author. e-mail: sintekal@gmail.com attribution-non-commercial 4.0 international license. consequences of temporal land cover changes on ecosystem services in babile elephant sanctuary, eastern ethiopia dejene w. sintayehu1* and awol s. ebrahim2 1 school of animal and range sciences, haramaya university, p.o. box 138, dire dawa, ethiopia 2 school of plant sciences, haramaya university, p.o. box 138, dire dawa, ethiopia abstract: land cover (lc) change has been identified as one of the leading drivers of change in the ecosystem and its services. however, information on the impact of temporal land cover change on the ecosystem and ecosystem services in ethiopia is largely unknown. thus, this study examined the impacts of temporal lc changes on the ecosystem and ecosystem services (ess) provision in babile elephant sanctuary (bes) during the period of 1977 to 2017 using a landsat image analysis and questionnaire survey. in bes, woodland covered the largest area in the year 1977, 1997 and 2017, followed by bushland and agricultural land. however, there was a consistent decline in woodland and bushland from 56.5% and 31.1% coverage in the year 1977 to 45.3 and 27.2% in the year 2017, respectively. agricultural land and settlements increased from the year 1977, when they covered about 3.5 and 0.1%, respectively to 2017, when they covered 17.3 and 3.4%, respectively. we found significant (p<0.05) differences in the social perception of the positive and negative impacts of land cover change on ecosystem services. the respondents recognized the negative impact of agricultural land expansion and settlement on the ecosystem such as the provision of wild food, livestock feed, medicinal plants, fresh water, fuel-wood, raw materials and climate regulation leading to an increase in food shortage and vulnerability to frequent drought and flood. therefore, it is necessary to take urgent measures to prevent the losses in ecosystem and ecosystem services as a result of land cover change that occurs because of human activities. keywords: agricultural land expansion; biodiversity; human well-being; human settlement; landstat image analysis; questionnaire survey 1. introduction protected areas play a major role in the conservation of biodiversity (rands et al., 2010; palomo et al., 2014). traditionally, protected areas have been established to safeguard important landscapes and seascapes, major species, and their habitats (haslett et al., 2010; watson et al., 2014). in the last few decades, there has been a major increase in conservation areas to reduce biodiversity loss and enhance ecosystem integrity, function, and services (lopoukhine et al., 2012). moreover, there is the convention on biological diversity (cbd) of aichi biodiversity target 11 to make 17% of the terrestrial surface and 10% of the marine realm ecosystem into the protected area by 2020 (cbd, 2010). currently, the amount of area assigned as protected area globally is 17 million km2 (12.7% of the land surface) and 6 million km2 (1.6% of the marine surface) (cbd, 2010). however, extra land to set aside for conservation of biodiversity are challenged by the globally rising demand for food and other purposes, creating trade-offs between areas dedicated to biodiversity conservation versus agriculture (smith et al., 2010). therefore, there is a need to find an optimal balance between conservation and development especially in developing countries, where addressing widespread food insecurity and poverty is a regional priority. over the past few centuries, significant changes in africa’s ecosystems and their biodiversity have been observed (kareiva and marvier, 2012). these changes have resulted in shifts in biodiversity and ecosystem conservation approach, moving from the wildernesscenter towards human wellbeing and nature thinking, in which the relationship among nature and humans are well considered (kareiva and marvier, 2012). thus, protected areas should provide habitats for many species, but they also provide essential goods and ecosystem services (es) for human well-being (palomo et al., 2014; watson et al., 2014). in africa, although ecosystems and es have been documented to support the livelihoods of many poor people (davies, 2002), there is scarcity of scientific knowledge to identify important areas for conservation action where biodiversity conservation will produce the greatest benefits for es for many poor people who depend on natural resources (ma, 2005; reyers et al., 2009; egoh et al., 2011). the majority of peoples in africa depend on a continuous supply of es from nature to society such as provisioning of wild plant and animals for protein, wood for cooking, water for drinking or poles for fencing dejene and awol east african journal of sciences volume 14 (1) 39-50 40 (guzha et al., 2018). even if africa’s ecosystems provide bundles of es, the services they deliver are seriously threatened. for instance, millennium ecosystem assessment (ma, 2005) showed that more than 60% of es are seriously threaten or transformed, and affecting our commitments to enhance the production of food, fuel, and fiber; regulation of water supplies; and reduce our exposure to natural hazards like drought and floods (kareiva et al., 2007; swinton et al., 2007). therefore, it is important to safeguard ecosystems and their services. land cover (lc), change in the surface cover on the land, has been highlighted as one of the leading direct drivers of terrestrial ecosystem change (ma, 2005; reyers et al., 2009; guzha et al., 2018). land cover change is the changes in the natural habitats into human mediated ecosystems such as crop cultivation, settlement, and grazing that changes the biogeochemical cycles, hydrology, and climate of an ecosystem (reyers et al., 2009). for instance, studies showed that conversion of the natural ecosystem into agricultural land can have direct consequences on agricultural productivity through loss of pollination and disease regulation services which may be considered as an ecosystem disservice (rientjes et al., 2011; abram et al., 2014; sérgio et al., 2017). it also drives biodiversity loss through habitat loss and fragmentation (reyers et al., 2009). therefore, there is a critical need to protect areas that are important to support the provisioning of es (chan et al., 2006) in africa where the conversion of the natural ecosystem to agricultural land is expanding at an alarming rate (barbier, 2004; gibbs et al., 2010). although a few studies have examined and mapped es as a function of lc change, such studies are inadequate in east africa. for instance, out of 153 es case studies reviewed at global scale by seppelt et al. (2011), over 50% of the studies were located in only six countries outside africa (us, china, sweden, uk, mexico and canada) and no such studies have been conducted in east africa. further, very few of the studies analyzed multiple es (seppelt et al., 2011). moreover, case studies of land cover change in africa have also been conducted to examine the effects on single es (chan et al., 2006; reyers et al., 2009; winowiecki et al., 2015; sérgio et al., 2017; guzha et al., 2018). thus, assessment of the impact of temporal lc change on multiple es is necessary in order to implement appropriate land use management. the aim of this study was to examine the impact of temporal land cover (lc) change on elephant sanctuary (es) in babile elephant sanctuary (bes), eastern ethiopia. 2. material and methods 1.2. study site babile elephant sanctuary (bes) was established in 1970 to protect the only viable elephant population in the horn of africa. the sanctuary is situated in the trans-boundary area between oromia and somali national regional states, and covers an area of 6892 km2. it is located 560 km east of addis ababa (capital city of ethiopia) and 45 km east of the city of harar (capital of harari national regional state). its geographical position is within latitudes of 08o22'30"09o00'30"n and longitudes of 42o01'10"43o05'50"e (figure 1) and has an elevational range of 850m to 1785m above sea level. topographically, it is predominantly characterized by flat to gentle slopes which comprise 84% of the total bes area while the remaining 16% consists of complex valleys and deep gorges. four main drainage river valleys (fafem, daketa, erer and gobele) rise from garamuleta-gursum highlands, and these extend southwards through the sanctuary to join wabi shebelle river basin. a wide range of wildlife species inhabit bes including the african elephant (loxodonta africana), lion (pantehera leo), leopard (p. pardus) and hamadryas baboon (papio hamadryads). bes is also shelter for a range of antelope species and birds. figure 1. location of babile elephant sanctuary and surrounding districts, eastern ethiopia. dejene and awol ecosystem services 41 2.2. image acquisition, processing, and classification landsat images were used to analyze land-cover change between the years 1977, 1997 and 2017. dry season and cloud-free landsat images (two images per assessment year path-165 raw-054 and path-166 raw-054) with the spatial resolution of 30m were accessed from the united states geological survey (usgs) earth explorer (http://earthexplorer.usgs.gov). the acquisition of data was carried out during the months of december, january, and february. satellite images of the year 1977, 1997 and 2017 were imported in arcgis 10.2 for processing and analysis. world geographical system (wgs) 1984 geographic coordinate system were used and projected to universal transverse mercator (utm 37n) zone for further analysis. all images were geo-referenced and checked for sensor imperfections to assure consistency across three study years. to minimize scene-to-scene variability caused by the effects of solar zenith angles, earth-sun distance, atmospheric influence, and sensor differences (thomas et al., 1987; cogliati et al., 2015) images were pre-processed using geometric and radiometric corrections. after all the images were corrected in the same way, all scenes from the same year were mosaicked together to cover the study area. satellite images were classified into six land cover classes (table 1) according to the usgs standard classification scheme (mohan et al., 2011) using maximum likelihood supervised classification. training sites (n=48) were developed and signature file was created to be used in the supervised land cover change classification by using arcgis 10.2. the classified images were verified using ground control points (n=48) across the study area. envi 5.0 was used for accuracy assessments. envi was used to evaluate change detection between the years using a change detection matrix (see figure 2 for a schematic flow chart of the methodology). table 1. the description of the land cover classes used in bes, ethiopia. lc classes general description agricultural land areas of land ploughed or prepared for crop growing (i.e., both areas identifiably under crop agriculture and land under preparation). bushland areas with shrubs, bush and small trees in which multiple stems and branches are produced from the base of the main stem. woodland areas dominated by acacia species with mean height of above 5 m and the canopy cover ranges from 10% to 40% for open woodland and above 40. bare land areas with essentially no vegetative cover riparian forest a type of forest found along the major perennial rivers. the vegetation is usually evergreen (due to continuous water supply from the rivers). settlement land, which is mainly covered by rural villages figure 2. flowchart showing the procedures employed to arrive at the final lc map. 1977, 1997 and 2017 landsat image image processing 1. re sampling 2. enhancement 3. layer stacking 4. subsetting literature review image mosaic for each year run classification supervised classification prepare training points (samples) maximum likelihood classifiers field visit for ground truthing accuracy assessment final lc map dejene and awol east african journal of sciences volume 14 (1) 39-50 42 2.3. focus group discussion and household interview identification of the different es and associated functions were done on the basis of an integrated es assessment framework developed by de groot et al. (2002). ecosystem services in this paper are to refer “both tangible goods and intangible services provided by the park ecosystem” as used by the millennium ecosystem assessment (ma, 2005). these services include regulating, provisioning and cultural services that directly influence human wellbeing and supporting services needed to sustain the provision of other services (ma, 2005). since almost all population in and around bes depends on agriculture production, it is reasonable to assume that es indicators related to the sustainability of agricultural (livestock and crop) production are in high demand. the majority of the human population does not have access to treated water for domestic use. finally, climate regulation is an important global es. therefore, considering the above background, baseline es indicators were developed as guiding indicators for the focus group discussion. we conducted the focus group discussions (fgds) from december 2016 to may 2017 in a total of eight districts with people from 16 villages, who live inside (n=8 villages) and adjacent (n=8 villages) to the bes. fgds were done with at least 10 people (nyumba et al. (2018) in each village and were mainly elders and ecosystem users that were able to recollect events in the land cover and ecosystem service changes in bes. thus, the fgd participants were selected purposively who had been living in the respective location for at least 40 years and willing to fully engage in a group discussion. the average age of the participants involved in fgds was 55. the fgd was meant to validate checklists of es drawn from the above background and investigate additional services provided by the study area (table 2). the fgd allowed exchange of information and interactive discussion of community members (interviewees), guiding each other in conceptualizing questions while giving researchers with important insights into views and perceptions. the discussions were guided using a checklist of questions related to land cover change and its drivers as well as their effect on ecosystem and ecosystem service change in the area. participants of the fgd were inquired to reach an agreement concerning all questions. this supported researchers to obtain better estimates for each community (e.g. regarding es, land cover etc.). a questionnaire was developed on the basis of the results of the fgds for the household survey. table 2. demographic characteristics of communities participating in focus group discussions. district number of participants female participants [%] avg. age avg. education [years] avg. education of females [years] midhega tola 11 54.5 56 5 3 fedis 10 40.0 47 3 2 babille oromiya 13 53.8 62 8 5 gursum 10 60.0 51 4 5 babille somali 10 50.0 63 5 4 giraw 11 36.4 48 6 7 meyu 12 33.3 55 3 2 haromaya 12 41.7 59 8 7 total 89 46.1 55 questionnaire interviews were conducted with samples of respondents from 16 villages in 8 districts to gather information on the history of land cover and associated ecosystems and es change (table 3). a total of 100 key informants who were mainly ecosystem users were interviewed (inside bes, and outside bes located at least 0.1-5 km apart from bes). the average age of the respondents was 47. perceptions and awareness of respondents on current land cover types of bes in relation to es as well as the trend of different land cover types and es over the last four decades and reasons why land cover types and es have changed were captured. moreover, the questionnaire addressed issues regarding land cover trend and livelihood changes in the communities as well as individuals’ perceptions on the trends of es provision change over time as a result of the land cover change. the interviewees ranked the areas as ‘‘low important”, ‘‘medium” or ‘‘highly important” to provide es to people’s livelihoods following the methods of marianne and patrick (2013) and bengtsson et al. (2019) in the year 1977 and 2017. we also examined how respondents explained the effect of lc change (either positive or negative) on the es. finally, the respondents were requested to identify es that were impacted by each lc change type. furthermore, the respondents scored that the intensity of each lc change impact varied from 1 (low intensity) to 24 (maximum intensity). unselected es were rated as neutral. https://www.google.com.et/search?tbo=p&tbm=bks&q=inauthor:%22marianne+kettunen%22&source=gbs_metadata_r&cad=7 https://www.google.com.et/search?tbo=p&tbm=bks&q=inauthor:%22patrick+ten+brink%22&source=gbs_metadata_r&cad=7 dejene and awol ecosystem services 43 table 3. demographics characteristics of communities participating in questionnaire interviews. district number of participants female participants [%] avg. age avg. education [years] avg. education of females [years] midhega tola 12 66.7 54 6 6 fedis 12 41.7 38 4 3 babille oromiya 12 50.0 57 7 4 gursum 12 58.3 48 6 5 babille-somali 13 46.2 51 4 6 giraw 13 38.5 56 3 6 meyu 13 30.8 32 5 3 haromaya 13 46.2 43 6 5 total 100 47 47 2.4. data analysis descriptive statistics was used to present land use land cover change within and between years (1977, 1997 and 2017). differences between the perceived impacts of the lc change on ecosystem services were explored using a non-parametric kruskal–wallis statistical test. all analyses and graphical presentations were performed using r statistical program (version 3.2.2, r core team, 2015). 3. results 3.1. land cover (lc) classes and changes in bes the study had an overall classification accuracy of 93.6%. in babile elephant sanctuary, woodland covered the largest area in the years 1977, 1997 and 2017, followed by bushland and agricultural land (table 4). however, there was a consistent decrease in woodland and bushland from 56.5 and 31.1% coverage in the year 1977 to 45.3 and 27.2% in the year 2017, respectively. the share of riparian forest cover during the study period (1977-2017) also showed a downward trend from 8.6 to 6.3 and 6.3 to 3.1% in the years 1977 to 1997 and 1997 to 2017, respectively (table 4). agricultural land, bare land and settlements increased from the year 1977, when they covered about 3.5, 0.3 and 0.1%, respectively to 2017, when they covered 17.3, 3.7 and 3.4%, respectively (table 4; figures 3). table 4. area and proportion of land cover in babile elephant sanctuary in 1977, 1997 and 2017. land cover type 1977 1997 2017 area (ha) proportion (%) area (ha) proportion (%) area (ha) proportion (%) riparian forest 74918.97 8.8 54793.17 6.3 27145.17 3.1 agricultural land 30428.64 3.5 91725.93 10.5 151408.62 17.3 bare land 2462.94 0.3 11688.39 1.3 32246.91 3.7 bushland 271496.88 31.1 245813.04 28.1 237617.73 27.2 settlement 1202.59 0.1 9632.07 1.1 29446.56 3.4 woodland 493548.57 56.5 460405.44 52.7 396193.88 45.3 total 874058.6 100 874058.6 100 874058.6 100 table 5. area and rate of land cover change in babile elephant sanctuary between 1977 to 1997 and 1997 to 2017. land cover type 1977 to 1997 1997 to 2017 area (ha) rate (ha yr-1) change (%) area (ha) rate (ha yr-1) change (%) riparian forest -20125.8 -1006.3 -2.3 -27648 -1382.4 -3.2 agricultural land 61297.3 3064.9 7.0 59682.7 2984.1 6.8 bare land 9225.5 461.3 1.0 20558.5 1027.9 2.4 bushland -25683.8 -1284.2 -2.9 -8195.3 -409.8 -0.9 settlement 8429.5 421.5 1.0 19814.5 990.7 2.3 woodland -33143.1 -1657.2 -3.8 -64211.6 -3210.6 -7.3 dejene and awol east african journal of sciences volume 14 (1) 39-50 44 figure 3. a comparative map showing the actual land use land cover change in babile elephant sanctuary in 1977 (a), 1997 (b) and 2017 (c). 3.2. potential ecosystem services provided by bes focus group discussion identified 24 (7 provisioning, 7 regulating, 5 supporting and 5 cultural) es provided by bes (table 6 and figure 4). table 6 shows the description of the potential supply of four es (provision, supporting, regulation and cultural es). provision of food, water and raw materials, water-flow regulation, erosion control, climate regulation and soil formation and nutrient cycling were the most important es provided by bes. the area was also serving as an important site of eco-tourism as well as research and education due to a combination of topography and ecosystem networks (table 6). table 6. ecosystem services (es) provided by babile elephant sanctuary, eastern ethiopia. es category sub-es type services provided by the sanctuary’s ecosystem provisioning services wild food wild foods and fruits water provision provision of water for multiple purpose raw materials use of wood and sand for different purpose livestock feed animal fodder fuelwood fuel wood and charcoal wood medicinal plants medicinal plants for human and livestock disease cultivation production of crop, grazing land and bee hive regulating services climate regulation regulate microclimate water regulation regulates different water sources desertification regulation reduce expansion or invasion of desert air purification regulation of air quality waste regulation waste treatment, recycling and reduction noise regulation reduce disturbance and sound noise erosion regulation holding soils, prevent wind, sheet and gully erosion disease regulation pest and disease control supporting services nursery growth place for plant species and habitat for wildlife refugium place for living organisms soil formation soil development and formation nutrient cycling nutrient cycling and retention cultural services recreation opportunities for recreational activities ecotourism opportunities for tourism activities spiritual traditional beliefs, religious significance research and education provide services for formal and informal education dejene and awol ecosystem services 45 note: higher numbers display a higher provision. 1 = low important; 2 = medium importance; 3 = very important to provide ecosystem services (n=120). figure 4. average ratings of the trends of ecosystem services delivery change from babile elephant sanctuary between 1977 and 2017. 3.3. perceived impacts of land cover (lc) change on ecosystem services we found significant differences among the perceived impacts of lc change on nineteen ecosystem services. respondents perceived that services such as the provision of wild food, medicinal plants, raw materials, livestock fodder, fuelwood, climate regulation, water cycling, biomass production and provision of habitat for living things were negatively impacted as a result of the expansion of agricultural land and settlements (table 7). conversely, natural ecosystem i.e., riparian forest, bushland and woodland were perceived as providers of wild foods, medicinal plants, raw materials, livestock fodder, fuel wood, noise regulation, climate regulation, hazard regulation, biomass production, habitat for wild animals, water cycling, ecotourism and education services (table 7). dejene and awol east african journal of sciences volume 14 (1) 39-50 46 table 7. kruskal–wallis test and dunn groups to compare the impact of land cover change on ecosystem services. ecosystem service riparian forest agricultural land bare land bush land settlement woodland kruskalwallis test wild foods +(a) -(a) -(a) +(a) -(a) +(a) 25.2* medicinal plants +(a) -(a) -(a) +(a) -(a) +(a) 17.4* raw materials +(a) -(a) -(a) +(a) -(a) +(a) 23.8* livestock fodder +(a) -(a) -(a) +(a) -(a) +(a) 74.3* fuel wood +(a) -(a) -(a) +(a) -(a) +(a) 44.2* water supply +(a) -(a) -(a) +(a) -(a) +(a) 52.1* fresh air +(a) -(a) -(a) +(a) -(a) +(a) 19.4 disease control -(b) +(b) +(b) -(b) -(a) -(b) 28.7 noise regulation +(a) +(b) +(b) +(a) -(a) +(a) 34.1* waste regulation +(a) +(b) -(a) +(a) -(a) +(a) 25.3* climate regulation +(a) -(a) -(a) +(a) -(a) +(a) 20.7* erosion control +(a) -(a) -(a) +(a) -(a) -(a) 9.25* gas regulation +(a) +(b) -(a) -(b) -(a) +(a) 16.2 pollination +(a) -(a) -(a) +(a) +(b) +(a) 29.7 hazard regulation +(a) -(a) -(a) +(a) +(b) +(a) 35.4* nutrient cycling -(b) -(a) -(a) +(a) -(a) -(a) 18.4* soil formation -(b) -(a) -(a) -(b) -(a) +(a) 26.3* water cycling +(a) -(a) -(a) +(a) +(b) +(a) 33.8* biomass +(a) -(a) -(a) +(a) -(a) +(a) 19.2* habitat +(a) -(a) -(a) +(a) -(a) +(a) 14.7* ecotourism +(a) +(b) -(a) +(a) +(b) +(a) 22.1* spiritual values +(a) -(a) -(a) +(a) +(b) +(a) 30.6 recreational value +(a) -(a) -(a) -(a) -(a) -(a) 26.2* cultural heritage +(a) -(a) -(a) -(a) +(b) +(a) 22.7 education +(a) +(b) +(b) +(a) +(b) +(a) 31.5* note: * = statistically significant at 5% probability level. letters in parentheses represent statistically different groups as identified by the dunn test. bold ones represent the most remarkable results. 4. discussion in general, out of the six land cover (lc) types identified in babile elephant sanctuary (bes), three of them, namely, agricultural land, settlements and bare land, increased in size and proportion over 40-year period while riparian forests, woodland and bushland declined in cover, suggesting that natural ecosystem was converted into agricultural land, settlements and bare land. our study demonstrated that land cover change in semi-arid ecosystem of eastern ethiopia was perceived and identified as one of the factors that caused change in ecosystems and their services, particularly in and around protected areas. a total of 55 plant species composed of 24 families were recorded in babile elephant sanctuary (bes) (abdala and fenetahun, 2017). we found that agricultural land has been increasing at the highest rate for the last four decades compared to other land cover (lc) types during the study period (1977–2017). in contrast, natural habitats (riparian forest, bushland and woodland) were lost substantially during the study period with an annual average loss rate of 4475 ha. consistent with the results of this study, yirmed et al. (2008) revealed that since in 1970, the natural area of bes has shrunk by an estimated value of 82% as a result of anthropogenic factors. current ethiopian policy that is increasingly discouraging pastoralism in favor of permanent settlement and population growth is the major factor for the observed land cover change in babile elephant sanctuary (bes) (gebeye, 2016). similar to the results of other studies (mc granahan and satterthwaite, 2003; bailey et al., 2015), we found that land cover change was correlated with change in the overall provision of es. when the natural ecosystems are lost, es such as the provision of wild foods, livestock fodder, raw materials and medicinal plants, and recreational value are also lost (figure 5), all of which are fundamental to human wellbeing. this study indicated that provisioning services including harvesting and collection of food, raw materials, medicinal plants, and fuel-wood, fodder provision for livestock and water supply were the most important ecosystem provided by the area. communities around the study area have a long tradition of using plants for curative purposes against human and livestock diseases because of lack of access to hospitals, and medical and veterinary facilities. moreover, the sale of medicinal plants has become a significant source of income within the communities around babile elephant sanctuary (bes). many plants have been also collected for housing and fencing materials. in-line with other study conducted in other part of africa (shackleton et al., 2007), wild foods and fruit collection for household consumption or for dejene and awol ecosystem services 47 sales are common in the study area especially for herders and school children. the fuel-wood collected from bes was accounted for the major energy source. similarly, shackleton et al. (2007) also reported that raw material from forest potentially contributed approximately 28% to the gross income of rural livelihoods in south africa. fuel-wood accounts for about 35% of energy consumption in african countries and represent a valuable commercial commodity in peri-urban areas (eftec, 2005). a study conducted in madagascar showed that estimated value of fuel-wood for communities per household/ year was $39 (shyamsundar and kramer, 1996). the fuelwood gathered from the natural forest amounts to about 15% of the average household annual income, valued at $279. sale of medicinal plants is a common source of income, with yearly earnings of $2.9 million (fao, 2002). similarly, collection and sale of medicinal plants is very common and has become an important source of income in bes. like other african countries (bowen-jones et al., 2003), fodder provision for livestock was the other most important provision services provided by the study area. the ecosystem of bes plays interlinked roles in the service of water provision: water-flow regulation and water-quality. however, many of the ecosystem services (es) provided by the study area decreased and rated to be of medium importance in 2017. the reason might be that conversion of natural ecosystems or forest area to agriculture reduced the provision of important es such as wild food and raw materials. consistent with the results of this study, the decline in ecosystem provisioning services due to land cover change as a result of increased crop cultivation activities have been documented in west africa (leh et al., 2013). our results have demonstrated that lc change has large impacts on the provision of es. the results of this study have showed that regulating services that are of high value to the area were mainly linked to climate regulation, agricultural production, including water regulation, desertification regulation, disease and pest control, and erosion control. similar to other semi-arid ecosystem, the area is highly susceptible to climate change and desertification. the weather patterns in this area (most notably the cutoff lows) result in frequent floods, which have an enormous impact on the region’s economy (billi et al., 2015). in line with other previous studies (lamarque et al., 2011; brancalion et al., 2014; smith and sullivan, 2014), bes plays a vital regulating ecosystem role by regulating the local climate variation, retaining soils, and preventing soil erosion. however, most regulating and supporting es were reported to have a higher delivery from the study ecosystem in past than in 2017. better es such as climate regulation, desertification regulation, nutrient cycling, soil formation, and erosion control were recognized to have delivered in the year 1977 than in 2017. desertification (hulme et al., 2001), emergence of pests and disease (tanser et al., 2003) and soil erosion (beniston, 2003) are being accelerated by local and regional land cover changes in africa due to ecosystem change. floods have often devastated semi-arid east african ecosystem, for instance, the 1998 el niño floods killing more than 4000 people (galvin et al., 2001). rural people around the study area depend on subsistence farming and livestock production for their survival and cultivate crops such as groundnut, maize, and sorghum, and rear cattle, camel, sheep and goat using minimal inputs. using such practices, farmers and pastoralist rely heavily on es relating to soil fertility, water supply, rangeland productivity enhancement and regulation, erosion prevention, and pest control. soil fertility through the accumulation of soils and organic matter is arguably one of the valuable supporting es in bes. studies showed that expansion of agricultural land in the expense of natural ecosystem can have impact on es provision (dale and polasky, 2007), thus resulting in reduction of productivity which might be considered as an ecosystem disservice (beniston, 2003; zhang et al., 2007). other similar studies showed that ecosystem enhances nutrients availability to crop and fodder production by reducing the need for synthetic fertilizers and fallow phases (campbell et al., 2008). in ethiopia, approximately 85% of the population’s livelihood is derived from agricultural activities; the role of supporting services in protecting livelihoods is extremely important (gebreselassie et al., 2016). cultural es provision includes eco-tourism and leisure, heritage sites, the use of natural ecosystem as rituals, spiritual worship, education and recreation is important es supplied by bes. eco-tourism is increasingly important source of income in east africa. thus, cultural es are vital to attract more tourists. of the cultural es, education and ecotourism services provided by bes was increased and was also rated most important for securing people’s livelihood in 2017 (figure 5). the area is one of the eco-tourism and recreational destinations in eastern ethiopia. similarly, in 2000, tourism contributed an income of $10.7 billion in africa (gauci et al., 2001; neto, 2003; fayissa et al., 2008). the global contribution of africa in tourism sector increased from 3.3% in 1990 to 3.9% in 2000 (neto, 2003). this study has demonstrated that for many years, bes has served scientists as an important study area to address many ecological and conservation research questions. this might be attributed to africa’s rich wildlife fauna and flora with large number of endemism (maswera et al., 2009) and culture. to safeguard tourism and recreation es and enhance people’s livelihood, biodiversity and cultural es must be protected. on the other hand, spiritual values in bes were rated least important and their importance decreased sharply in 2017 in comparison with 1977. this could be caused by societal modernization and changing religious beliefs. similarly, the recreational value of bes has been declined, which dejene and awol east african journal of sciences volume 14 (1) 39-50 48 might be due to shortage of time as subsistence farming practices being time-consuming. 5. conclusions the results of our study have demonstrated that land cover change has been identified as one of the leading drivers negatively influencing natural ecosystem and their ecosystem services in babile elephant sanctuary (bes). consistently, increasing expansion of agricultural land and the drastic decline in ecosystem services have been observed in the bes ecosystem over time. therefore, trans-sectoral policy development is needed to harmonize natural resource policies with other sectors, such as investment, agriculture, energy, and land administration. in addition, a plausible regulating es based program would be crucial for socioeconomic development and ecological stability in the regions. these results are a firststep towards understanding the impact of land cover change on ecosystem and es and identifying the underlying mechanisms in the study area. further studies with experimental manipulation, are required to thoroughly test the effect of land cover change on es. 6. acknowledgements we sincerely thank haramaya university, ethiopia, for funding this research. 7. references abram, n.k., meijaard, e., ancrenaz, m., runting, r.k., wells, j.a., gaveau, d., belier, a.s. and mengersen, k. 2014. spatially explicit perceptions of ecosystem services and land cover change in forested regions of borneo. ecosystem services, 7: 116-127. abdala, t. and fenetahun, f. 2017. review on floristic diversity and threated plant species in babile elephant sanctuary in east hararge, ethiopia. american journal of environmental science and engineering, 1: 1-6. adams, w.m. 2004. against extinction: the story of conservation, earthscan publications, london uk. bailey, k.m., mccleery, r.a., binford, m.w. and zweig, c. 2015. land-cover change within and around protected areas in a biodiversity hotspot. journal of land use science, 11: 154-176. bakker, w.h., gorte, b.g.h., janssen, l.l.e., poh, c., prakash, a., reeves, c.v., weir, m.j.c. and woldai, t. 2001. principles of remote sensing, itc, enschede, the netherlands. barbier, e.b. 2004. explaining agricultural land expansion and deforestation in developing countries. american journal of agricultural economics, 86: 1347-1353. bengtsson, j., bullock, j.m., egoh, b., everson, c., everson, t., o’connor, t., o’farrell, p.j., smith, h.g. and lindborg, r. 2019. grasslands more important for ecosystem services than you might think. ecosphere, 10(2):e02582. 10.1002/ecs2.2582. beniston, m. 2003. climatic change in mountain regions: a review of possible impacts. climate change, 59: 5-31. billi, p, yonas, a. and rossano, c. 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ecological economics, 64: 253260. ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (1) 1–12 _____________________________________________________________________________________________ licensed under a creative commons *corresponding author. e-mail: nalemayehua@yahoo.com attribution-non-commercial 4.0 international license. the use of biofertilizer by smallholder farmers and its impact on productivity of pulsecereal cropping system in arsi zone, oromia regional state, southeastern ethiopia nigussie alemayehu ethiopian institute of agricultural research (eiar), p.o. box 2003, addis ababa, ethiopia abstract: commercial production and distribution of biofertilizer for increasing yields of pulse crops in ethiopia started as recently as two decades ago after the agricultural research system began working on biofertilizer. consequently, farmers have been inoculating seeds of pulse crops with rhizobium bacteria to get higher yields using rhizobium strains disseminated by the research system. similarly, smallholder farmers in lemu bilbilo and digelu tijo district (woredas) of arsi zone of the oromia regional state in southeastern ethiopia have been inoculating faba bean and field pea seeds with rhizobium bacteria for increasing yields of the crops since 2010. however, there is no empirical evidence for agronomic and agroecological benefits that the farmers obtain from using the technolgy. therefore, a methodical assessment was done to investigate the effects of biofertilizer (seed inoculation with rhizobium) on the productivity of faba bean and subsequently grown wheat and barley crops and the benefits that farmers obtain in terms of yield and sustainability of the farming system. both qualitative and quantitative data were collected from four kebeles in the two woredas through focus group discussions (fgd) and key informant interviews (kii) involving 150 farmers, agricultural experts, development agents, researchers, and community leaders. the results revealed that smallholder farmers who planted rhizobium-inoculated faba bean seed gained additional yield benefits of 79%, 66%, and 42% for faba bean, wheat, and barley, respectively, over farmers who planted uninoculated seeds. in addition, farmers reported that they derived a range of other benefits which included improved soil fertility, need for lower amounts of nitrogen fertilizers to produce cereals, low faba bean disease incidence, more biomass production for returning to land as a crop residue, and larger-sized faba bean seeds that take shorter time to cook. the farmers also reported an opportunity to grow faba bean profitably on less fertile land. it is concluded that planting rhizobiuminoculated faba bean seed significantly increased the yields of all three crops grown in the rotation system, with significant implications for enhanced agroecological benefits and sustainabile pulse-cereal production system. keywords: cereal crops; crop rotation; faba bean; pulse crops; seed inoculation with rhizobium; wheat and barley 1. introduction nitrogen and phosphorus are mineral nutrients that limit plant growth most (sanchez, 2002). they are the most deficient nutrients in most of ethiopian soils (mamo et al., 1988; tsegaye, 1992). more than 85% of ethiopian soils contain insufficient amounts of nitrogen for sustaiabale and profitable crop production (ata, 2012). therfore, the two nutrients in particular have to be replenished through mineral or organic fertilizers to sustain crop production. the most common source of nitrogen used in ethiopia is the mineral fertilizer urea. although farmers realize that crop yields are higher with application of urea, they very often use lower rates of the fertilizer than the rates recommended by the research system. this is attributed to inadequate supply and escalating prices of mineral fertilizers. soil management strategies that are solely dependent on mineral fertilizers, in addition to being unaffordable to resource-poor farmers, cause a serious threat to human health and the environment (pearson et al., 1995; löschenberger et al., 2008). the use of biological n-fixation through cultivating pulse crops as a source of dietary protein as well as a supplementary way of improving soil fertility and environmental protection has been a subject of considerable research since the early 1980s (beyene, 1988). in ethiopia, the tradition of crop rotation where the cycle of continuous production of cereals is broken by producing pulse crops as a means of maintaining soil fertility and diversifying agricultural products is a common practice (gorfu, 1998; taa et al., 1997). likewise, the ability of pulse crops to restore soil fertility had been realized and exploited by farmers also in other parts of the world long before the symbiotic association between bacteria and the host plant was scientifically established (lim and burton, 1982; hirsch, 2009). nigussie alemayehu east african journal of sciences volume 14 (1) 1–12 2 rhizobia infect the legume root and form root nodules in which they convert atmospheric nitrogen into ammonia, which then can be utilized by the plant to produce valuable proteins, vitamins and other nitrogencontaining compounds that are required for normal growth and development of plants and thus better yields (keyser and li, 1992). exploitation of beneficial microbes as biofertilizer is of paramount importance in agriculture not only for their economic benefits and cost effectiveness but also for their potential role in food safety and sustainable crop production (pearson et al., 1995; aryal et al., 2003; burger et al., 2008; löschenberger et al., 2008). the term biofertilizer refers to the use of various live microorganisms that enhance soil fertility by fixing atmospheric nitrogen, solubilizing or mineralizing phosphorus and potassium or decomposing organic wastes or by producing plant growth-promoting substances at the root zone (mohammadi and sohrabi, 2012). biofertilizers, as one of the important components of sustainable agriculture, are products containing living microorganisms which have the ability to mobilize nutritionally important elements from non-usable to usable form through biological processes and they have the potential to increase the production of crop by improving yield and quantity (glazer and nikado, 2007). biofertilizers are valuable to the environment as they enable reduced use of chemical fertilizers since they contain naturally occurring micro-organisms that are biologically multiplied to improve soil fertility and crop productivity in many parts of the world (ifpri, 2010). they are also relatively low-cost source of nitrogen for smallholder farmers in ethiopia (gorfu et al., 2000). rhizobium inoculants coated on seeds of pulse crops before planting not only enhance growth and yield of the pulse crops but also provide nitrogen and organic carbon for subsequent or associated crops; and incorporating residues of pulse crops back into the soil will make this effect even more significant (de boef et al., 1996; gan et al., 2015; masso et al., 2015). in ethiopia, commercial production and distribution of rhizobium inoculants were started some twenty years after the research took the initiative to work on biofertilizer. presently, some specific rhizobium strains are being produced and supplied for faba bean, chickpeas, lentils, field pea, common bean, soybean and mung bean production (hailemariam and asfaw, 2015; assefa, et al., 2018). it is also worth-noting that pulse crops not only avail soil nutrients through nitrogen fixation and nutrient solubilization but also serve to ‘break’ cycles of different cereal pests as non-host crops (malhotra et al., 2004; kirkegaard et al., 2008; keneni et al., 2016). pulse crops offer these manifold merits to the farmer with only minimum external inputs as compared to cereals (keneni et al., 2006). the research system in ethiopia has pursued the approach to make use of biofertilizer to increase the nitrogen availability for the pulse crops through biological nitrogen fixation as well as for cereal crops that are cultivated following them (gorfu, 1998; taa et al., 1997; tolera et al., 2015; assefa et al., 2018; negash et al., 2018). despite availability of empirical evidence on the advantages of growing pulse crops in rotation with cereals, no conclusive results have been presented to show farm-level benefits derived from the legume crops as well as from subsequently grown cereal crops. therefore, a study was conducted in early 2016 to investigate the benefits that smallholder farmers arsi zone gained from using biofertilizer, which was promoted as in as part of the production package for faba bean to improve that yield of the crop and those of subsequently grown wheat and barley crops. the study was aimed also at elucidating other benefits that smallholder farmers may derive from using biofertilizer through enhancements of household incomes, livelihoods, and farming system sustainability. 2. materials and methods informed by a body of literature and reports from research and business organizations engaged in activities related to biofertilizers in ethiopia and extensive discussions held with relevant personnel of the institutions, the assessment was made in early 2016. these included discussions held with technical experts and director of mbi, the project coordinator of n2 africa-ethiopia which is housed by the international livestock research institute (ilri), ethiopia, and leaders of soil microbiology research at kulumsa and holetta agricultural research centers. after having general information about the status of research and the use of biofertilizer in the country, the assessment was conducted in four kebeles of arsi zone using participatory rural appraisal (pra) tools to gather data and information used to disclose facts embedded in this relatively new technology of restoring soil fertility. the methodology is specifically described as follows: 2.1. assessment area the assessment was conducted in two districts (woredas) of arsi zone (lemu bilbilo and digelu tijo), oromia regional state. each woreda was represented by two kebeles. a ‘kebele’ is the smallest local administrative unit in a district (woreda) in ethiopia. thus, lemu bilbilo woreda was represented by bekojinegeso and lemu-dima kebeles. digelu tijo woreda was represented by sagure-mole and burkitu-alkasa kebeles. ‘ the arsi zone was selected for this study as it is an area where the risks associated with cereal-cereal monoculture are high both at technical and policy levels and there is a need for aggressive introduction of inoculating seeds of pulse crops with rhizobium bacteria before planting particularly faba bean and field pea, nigussie alemayehu biofertilizer for enhancing productivity of pulse-cereal cropping system 3 which are the best and most preferred rotation crops with cereals in the area (keneni et al., 2016). the study sites are located some 200 to 35 km south-east of addis ababa, the capital city of ethiopia (figure 1). the four kebeles where the assessment was undertaken are situated within the very center of major production areas of faba bean, field pea, wheat, barley and highland oilseed crops such as linseed and ethiopian mustard. the kebeles are situated in the central plateau of arsi zone with a typical highland agro-ecological setting of altitude greater than 2500 m above sea level (table 1). the long-term average annual rainfall of the area is more than 1000 mm whereas the mean annual temperature ranges from 12-13 oc, with impressively minimum fluctuation (table 1). this combination of altitude, rainfall, and temperature is ideal for growing faba bean (keneni et al., 2006; 2007). thus, no other area more than the present kebeles could better depict the potential economic and environmental benefits accruing from application of biofertilizer. several strains of nitrogen-fixing bacteria have been identified and recommended by the research system for production of faba bean including strains 1018, 1035 and eal 110 (eiar, 2018). however, according to the woreda administration, development agents and researchers involved in the distribution of the biofertilizer, the strain eal 110 was the one most widely used by the farmers in the kebeles selected for this study. figure 1. map of the study area. table 1. geoclimatic descriptions of the four kebeles where biofertilizer was applied on faba bean. kebele altitude (m) (a.s.l.) * annual rainfall (mm) mean annual temperature (o c) min max mean min max mean burkitu alkasa 2558 1175 1211 1196 13 14 13.12 sagure mole 2586 1158 1205 1188 13 13 13.00 lemu dima 2812 1077 1144 1112 11 13 12.33 bokoji negeso 2793 1061 1124 1096 11 13 12.52 note: *a.s.l. = above sea level. altitude, and rainfall and temperature data were sourced from jarvis et al. (2008) and www.worldclim.org, respectively. 2.2. data collection and analysis both qualitative and quantitative data were collected in the assessment process. for collecting information and data, semi-structured questionnaires were developed, followed by focus group discussions (fgd) and key informant interviews (kii). field visits were made where the crops were still growing during the period of the assessment to corroborate facts asserted by participants of the fgd and kii. the fgd component was structured around a set of standardized participatory assessment tools to collect qualitative contextual data on the use of biofertilizer, the purposes and methods of the use and its impact on yield, profits, and household income. the preceding assessment tools were used in addition to the general situational description and information on the farming systems. the kii, which included farmers who used as well as who did not use rhizobium inoculants, was designed to capture the history and use of inoculants, sources of inoculants and details on any inoculantrelated impact on yield, livelihoods, and sustainability. the data collected and consolidated from the fgd and kii were designed to establish facts on (1) types of crops grown and rankings of their importance in terms of area of production and market values; (2) major constraints of crop production and their order of importance; (3) proportional distribution of crops produced by households (hh) for consumption, sale, seed or forage; (4) size of landholding and family size per hh; (5) proportional land allotment to crops and typical crop rotation patterns followed in the area; (6) practices of soil fertility maintenance through the use of chemical fertilizers and biofertilizer and the history and extent of use of rhizobial inoculants; and (7) http://www.worldclim.org/ nigussie alemayehu east african journal of sciences volume 14 (1) 1–12 4 general benefits of rhizobial inoculants in terms of the yields of the target legume as well as subsequent cereal crops, environmental sustainability in terms of reduction in the use of the chemical fertilizer urea for follow-on cereals. altogether, 158 (38 female) individuals representing farmers, development agents, woreda experts, community leaders, researchers and the private sector engaged in supplying biofertilizers took part in the interview and discussions. in order to quantitatively determine the benefits of biofertilizer on yields of faba bean and that of subsequent cereals rotated with the faba bean and incomes of the households (hhs), data were collected from face-to-face interviews of 145 farmers in the four kebeles. seventy-nine of the interviewees used rhizobia-inoculated seeds once or multiple times while the remaining sixty-six did not use any rhizobia-inoculated seeds. therefore, it was possible to generate data points enough to statistically determine the effect of biofertilizer on the yields of faba bean as well as wheat and barley following the inoculated-faba bean. the sas statistical package was used to process the quantitative data collected from individual interviews and perform t-tests and calculate cv values, while excel was used to construct frequency tables and pie and bar charts. 3. results and discussion 3.1. crop production system and use crop types, importance and use: the average landholding of a household (hh), which has an average family size of 6 persons, is 2.5 hectares (figure 2). however, this does not necessarily mean that every household owns land. for example, in one of the kebeles, out of 1078 hhs, only 500 hhs or about 46% of them posess land of their own while the remaining 54% of the hhs in that particular kebele are landless. figure 2. crop composition, average area allotment (in hectare indicated in parentheses) and relative distribution (%) of each crop per household in lemu bilbilo and digelu tijo districts (woredas) of arsi zone figure 2 depicts that almost a whole range of crops are grown in the area, wheat and barley being the major ones. these cereals take the lion’s share of the agricultural land allotment in both woredas, followed by faba bean and field pea and some tef only in burkitu alkasa kebele. oat is grown sometimes as a forage crop on marginal land. it is interesting to point out that during the fgd, at sagure-mole, production and consumption of grass pea (lathyrus sativus l.) was indicated to have been started only recently. especially female farmers asserted that the consumption of grass pea in every household doubled compared to the amount of faba bean or field pea consumed. production of the two oilseed crops, namely, linseed and ethiopian mustard, is also common in the two woredas but only small parcels of land are allotted to cultivate both crops. the data obtained from the fgd and kii indicated that the larger proportions of most of the crops produced by the households are marketed (figure 3). however, the proportion of crops meant for sale was the highest for oilseeds followed by pulses and cereals in the same order. the opposite holds true for consumption where 60% of the barley, 50% of the tef and close to 40% of the wheat produced are destined for home-consumption and about 10%, except for ethiopian mustard, is retained as seed for the next nigussie alemayehu biofertilizer for enhancing productivity of pulse-cereal cropping system 5 season. since the seed rate required for ethiopian mustard is small (belayneh and alemayehu, 1986), only four percent of the produce is retained by the hh. earlier reports also indicated that production of particularly cereal crops in ethiopia is mostly for consumption (60–80%), followed by sale (8-21%) and farmers mostly tended to sell more of high value pulse and oil crops (csa, 2017). figure 3. farmers estimates of the proportions of their crops used for consumption, sale and seed in lemu bilbilo and digelu tijo districts (woredas) of arsi zone during the 2016 main cropping season crop rotation patterns: farmers in the study area generally know the importance of growing different crops on the same plot of land in rotation. they even ascribe improved soil fertility and reduced incidences of crop diseases to cereal-legume crop rotation. a similar study in north shoa, ethiopia, also revealed that farmers are aware of the impact of legumes and fallowing on improving soil fertility but they do not have the scientific knowledge about the role microbes associated with legume root nodules play in improving soil fertility (teshome et al., 2018). these intuitive perceptions of farmers about the advantage of rotating crops of different species is corroborated by empirical research findings that crop rotation improves soil fertility restoration and soil health (gorfu, 1998; assefa et al., 2018) and soil physical and biological properties via increasing organic matter (negash et al., 2018). based on experiences accumulated over the years and generations and, most importantly, the rationale the farmers strive to match their needs and resources like land, seed and other inputs at their disposal, they follow some distinct crop rotation patterns in the area. nevertheless, three crop rotation patterns indicated in figure 4 stand as the most dominant and widely followed cropping sequences. figure 4. crop rotation pattern traditionally followed by farmers in lemu bilbilo and digelu tijo districts (woredas) of arsi zone during the 2016 main cropping season nigussie alemayehu east african journal of sciences volume 14 (1) 1–12 6 the arrangement of the first sequence, though including cereals, pulses and oilseeds, cannot be immune to foreseeable problems and thus technical disapproval as cereal-cereal mono-cropping cannot be disputed. even worse is the second pattern as the cereal-cereal sequence is interrupted by a pulse breakcrop only once in four years, which may make the system vulnerable to a range of biochemical as well as physical threats of sustainability as a large body of research findings reveal. for example, some authors recommended shorter rotations of pulse crops with cereals at least once every three years (parr et al., 1983; cox et al., 2010; gan et al., 2015). furthermore, including legumes in the rotation was found to be effective against pests and weeds through different mechanisms such as through being non-host crops and breaking the life cycles of crop-specific pathogens that would otherwise attack cereals (malhotra et al., 2004; kirkegaard et al., 2008; keneni et al., 2011; negash et al., 2018; niu et al., 2018); reducing the amounts of inocula of pathogens that could afflict subsequent cereal crops (krupinsky et al., 2002; niu et al., 2018); and improving the soil with essential microbes providing ecological services in nutrient cycling (bridge and spooner, 2001; lupwayi and kennedy, 2007; penton et al., 2014; niu et al., 2018). in some countries like canada, producers also follow a crop rotation scheme as a remedial measure against pests (the gov of saskatchewan, 2017). the risks associated with wheat-wheat monoculture being practiced in the four kebeles of the assessment is especially ominous as a result of excessive buildup of inoculums of the major diseases that are responsible for the failure of wheat varieties almost immediately after their release (keneni et al., 2016). an important point to note in the third pattern of rotation is that, fallowing agricultural land for one or two seasons is practised. scientific evidence supports te perception of farmers such that fallowing can serve as a means of additional way of restoring soil fertility, particularly to promote the release of nitrogen via decomposition of soil organic matter and mineralization of nitrogenous compounds contained therein. fallowing has such functions despite the fact that in the long-term, it relies on ‘mining’ the available soil n with depleting soil organic matter (gan et al., 2015). in the present context, however, fallowing seems utterly untenable as it poses a lost production opportunity in terms of land for one or more production seasons. this may exacerbate the problem of land scarcity in the face of increasing number of young farming households. it is also imaginable that fallowing a bare land, which is often the case with cultivated land, has rather a negative consequence on soil stability especially where there is overgrazing by an increasing number of livestock, which is typical for the assessment kebeles. furthermore, such heavy rainfall conditions as those prevailing in the areas where more than 1000 mm of rain is annually received (table 1), the rate of erosion would be exacerbated. in addition, unless the ground is sufficiently covered with protective vegetation, the loss of surface soil caused by the torrential rains will undoubtedly be dire. therefore, fallowing can no longer be a sustainable system in the face of ever-increasing pressure from increasing population in the rural setting on one hand and scarcity of cultivable land on the other. major problems of crop production in the target areas: although there may be an array of technical, technological, economic, biological and social (including policy-related issues) factors constraining agricultural production, farmers have identified some problems of highest priority in their respective kebeles (figure 5). the order of importance of the problems identified by the participants varied from kebele to kebele depending on the magnitude of incidence and households affected, but they essentially remained more or less similar. figure 5. major problems of crop production identified and ranked by the participants of the fgd and kii in the assessment kebeles in lemu bilbilo and digelu tijo districts (woredas) of arsi zone during the 2016 main cropping season. note that highest score signifies highest priority and lowest score least priority. https://www.frontiersin.org/articles/10.3389/fmicb.2018.01909/full#b11 https://www.frontiersin.org/articles/10.3389/fmicb.2018.01909/full#b46 https://www.frontiersin.org/articles/10.3389/fmicb.2018.01909/full#b60 nigussie alemayehu biofertilizer for enhancing productivity of pulse-cereal cropping system 7 3.2. the use and effect of biofertilizer on the yield of faba bean the results of the study revealed that the use of biofertilizer for faba bean production in the two woredas of arsi zone began in 2010. according to the records from the respective offices of agriculture for the two woredas, a total of 5,767 households (1,362 female-headed and 4,405 male-headed households) in lemu bilbilo woreda and 4,175 households (1,075 female-headed and 3,100 male-headed households) in digelu tijo woreda, were given a series of training on application of bio-fertilizer. the series of training were given not only to farmers but also to development agents (da), subject matter specialists (sms), supervisors and community leaders. furthermore, onfarm demonstrations were made by kulumsa agricultural research center (karc) for three consecutive years. consequently, it was possible to distribute 4,550 bags of biofertilizer to farmers growing faba bean and 1,703 bags for those growing field peas since the time of its introduction of the technology into the area. since each bag is prepared for a quarter of a hectare, implicitly 2,638 hectares of faba bean and 1,010 hectares of field pea were established with rhizobium-inoculated seeds during this period. all farmers who used biofertilizer invariably stressed that yields of crops, including that of faba bean, have generally improved significantly. however, they also underlined that in order to reap the full benefit of yield advantage accruing from biofertilizer, optimal combination of such factors as good quality seed, appropriate agronomic practices, including proper pest control management should be implemented. the farmers also noted that lemu bilbilo and digelu tijo woredas are among the pioneer woredas in ethiopia to have access to modern extension services through the swedish international development agency (sida)supported chilalo agricultural development unit (cadu) from the 1960’s to the 1970’s. thus, the key informants emphatically asserted that farmers in the two woredas are accustomed to trying out new agricultural technologies, modify them to suit their specific production and economic circumstances, or discard it altogether if they find it not suitable for addressing their needs. unlike in most other parts of ethiopia, even faba bean and field pea are grown in these woredas with application of chemical fertilizer, diammonium phosphate (dap) at the rate of 67 to 100 kg ha–1. accordingly, in both woredas, the use of biofertilizer in faba bean started in 2010 and, as stated above, farmers have been using biofertilizer ever since. in fact, some of the farmers have used inoculated seeds on the same plot of land more than once although research recommends that one-time application is sufficient for more than four to five years. this is because once the bacteria are inoculated, they perpetuate themselves even from the surrounding fields (lindemann and glover, 1996; abendroth et al., 2006). according to the same authors, frequent inoculation is not of any help because of competition between the established and new rhizobial introduction; but inoculation is critically needed if the native strain is not efficient, if the legume species was never grown before on the land or if the land was never cultivated to pulse crops. farmers in all the four kebeles unequivocally affirmed that the use of rhizobium inoculated seeds of faba bean enhanced the yield of the crop as well as restored and mainiatined soil fertility. the farmers reported that the increase in yield at times reached twice as much as the yield they used to obtain before the introduction of biofertilizer in the area. the farmers revealed that it was in fact the prospect of getting higher yields that enticed them to use rhizobium inoculated seeds mistakenly more than once on the same piece of land. their unanimous claim of the increased yield of faba bean due to biofertilizer was extrapolated using data collected from the a questionnaires and it was found that there was a highly significant (p < 0.01) increase in yield of faba bean from the use of rhizobium inoculated seeds in all the kebeles assessed (table 2). the table also shows that the average increase in faba bean yield from biofertilizer ranged from 40% (in lemu-dima) to more than 150% (in burkitu-alkasa) with 79% across the whole area. corroborating the results of this study, kwasi (2018) reported that farmers realized the significance of rhizobium seed inoculation and were willing to pay for production inputs for pulse crops including inoculant (kwasi, 2018). farmers attributed the increase in yield to plant characteristics that they think would ultimately contribute to seed yield of faba bean. according to their observation and perception, plants grown from rhizobium-inoculated seeds exhibited such characters as seedling vigor and and strong stems, a greater number of nodules, less abortive (sterile) flowers in which case flowering takes place from bottom to top, and ultimately well-filled and plump seeds. the results from the assessment are generally in agreement with the potential of biofertilizer that global experiences indicate (gan et al., 2015; kwasi, 2018) and even more so with the findings of research in ethiopia conducted in the past two decades (assefa et al., 2018). consistent with the perception of the farmers that rhizobiuminoculated plants grow and yield better, gan et al., (2015) reported that diversifying cropping systems with pulse crops enhanced soil water conservation, improved availability of soil nitrogen, and increased system productivity. nigussie alemayehu east african journal of sciences volume 14 (1) 1–12 8 table 2. the effect of biofertilizer on the yield of faba bean in the four assessment kebeles in lemu bilbilo and digelu tijo districts (woredas) of arsi zone during the 2016 main cropping season statistic bekoji-negesso lemu-dima sagure-mole burkitu-alkasa overall mean biofert (+) biofert (-) biofert (+) biofert (-) biofert (+) biofert (-) biofert (+) biofert (-) biofert (+) biofert (-) average (t ha–1) 2.94 1.76 3.03 2.16 2.72 1.64 3.30 1.29 3.00 1.67 range (t ha–1) 2.0–4.8 1.5–2.0 2.8–3.2 1.6–2.6 2.0–3.2 1.4–2.0 2.4–4.6 1.0–1.5 2.0–4.8 1.6–2.6 standard deviation 0.81 0.21 0.197 0.358 0.388 0.207 0.680 0.168 0.690 0.374 sample size (n) 26 20 16 15 20 18 17 13 79 66 test statistic (t) 3.503** 5.152** 7.096** 7.564** 9.083** cv (%) 2.3 1.2 0.6 1.7 1.4 1.3 2.1 1.3 2.3 2.2 yield increase (%) 67 40 66 156 79 note: * and ** respectively indicate that the differences are significant at 5% and 1% levels of significance; biofert (+) = with biofertilizer and biofert (-) = without biofertilizer. 3.3. the effect of inoculant on the yields of subsequent cereal crops as indicated above, wheat and barley are the two major cereals grown in the woredas assessed and faba bean or field pea are traditionally used as break crops in the crop rotation system. farmers in all the discussion groups had the view that the use of chemical fertilizer over the last several decades adeversely affected the fertility of their soil, i.e., made the soil less fertile and unhealthy. thus, they said, “we were taught in the training sessions by researchers, development agents, and woreda experts that the use of biofertilizer not only increases yields of pulses but also leaves behind a significant amount of nitrogen and organic matter (from the biomass [leaves and root material] from the faba bean plants) that will help to get a bumper harvest of the following cereal crop; therefore, we were so keen to accept and readily try the technology”. all the discussion groups pointed out that they were not disappointed by the results they got. they confirmed that both wheat and barley following cultivation of rhizobium-inoculated faba bean produced higher yields than they used to produce before the introduction of the biofertilizer int the area. analyses of the quantitative data from the kii (tables 3 and 4) also confirmed what was perceived by the farmers that the yield of the wheat crop following inoculated-seeds of faba bean was significantly (p < 0.01) higher than the yield of the wheat crop following faba bean grown without rhizobial inoculation (tables 3). the average increase in the yield of wheat was attributable to the effect of biofertilizer (i.e., 4.0 t ha–1 following faba bean with biofertilizer and 2.3 t ha–1 following faba bean without biofertilizer) scored a net increase of 73% or 1.7 t ha–1. since, on average, each household in the assessment kebeles alloted 0.904 ha of land to cultivation of wheat (figure. 2), the household got an additional produce of more than 1.5 tons, which could be ascribed to inoculation of faba bean seed with rhizobium. the benefits of biofertilizer reflected on the yield of barley were significant only in two of the four kebeles (table 4). in the highlands of arsi zone, before wheat became a popular crop, barley was the predominant crop with versatile qualities treasured by the populace a staple food or for making beverage (local beer). however, soon after bread wheat varieties were introduced and promoted in the region in the late 1960s and with the advent of “modern” lifestyle where bread making became common and its cultivation began expanding, barley production was marginalized and relegated to a second place after wheat. especially in areas that are suitable for the latter, the replacement was drastic (demissie, 1991; negassa, 1985; asfaw, 2000; keneni et al., 2007). nevertheless, the quantitative data obtained from the kii (table 4) indicate that the effect of biofertilizer on the yield of barley following faba bean was so significant that more than 35% of average yield increase was realized by farmers who used rhizobia-inoculated faba bean seed. the results generally concur with global and local experiences where cereal crops following pulse crops inoculated with the appropriate strains of rhizobium give better yields (gan et al., 2015; assefa et al., 2018). nigussie alemayehu biofertilizer for enhancing productivity of pulse-cereal cropping system 9 table 3. effect of faba bean-biofertilizer on the yield of subsequent wheat crop in lemu bilbilo and digelu tijo districts (woredas) of arsi zone during the 2016 main cropping season statistic bekoji-negesso lemu-dima sagure-mole burkitu-alkasa overall biofert (+) biofert (-) biofert (+) biofert (-) biofert (+) biofert (-) biofert (+) biofert (-) biofert (+) biofert (-) average (t ha–1) 4.00 2.33 4.47 2.57 4.69 3.35 5.27 2.000 4.61 2.78 range (t ha–1) 3.2–4.8 2.0–2.5 4.2–4.8 2.0–2.9 3.6–5.6 2.2–5.0 4.8–5.6 1.6–2.4 3.6–5.6 1.6–5.0 standard deviation 0.661 0.289 0.306 0.403 0.641 0.900 0.416 0.400 0.658 0.834 sample size (n) 14 13 13 11 19 8 13 13 59 45 test statistic (t) 4.14** 6.75** 3.57** 9.80** 7.42** cv (%) 1.6 1.2 0.7 1.6 1.4 2.7 0.8 0.20 0.14 0.30 yield increase (%) 74 73 40 163 66 note: * and ** respectively indicate that the differences are significant at 5% and 1% levels of significance; biofert (+) = yield of wheat crop following faba bean with biofertilizer and biofert (-) = without biofertilizer. table 4. effect of faba bean-biofertilizer on the yield of subsequent barley crop. statistic bekoji-negesso lemu-dima overall mean biofert (+) biofert (-) biofert (+) biofert (-) biofert (+) biofert (-) average (t ha–1) 4.225 3.100 3.350 2.250 4.050 2.857 range (t ha–1) 3.2–5.6 2.8–3.3 3.2–3.5 2.0–2.5 3.2–5.6 2.0–3.3 standard deviation 0.752 0.235 0.212 0.353 0.762 0.479 sample size (n) 18 15 20 12 38 27 test statistic (t) 3.20** 3.77** 3.91** cv (%) 1.8 0.8 0.6 1.6 1.9 1.7 yield increase (%) 36 49 42 note: * and ** respectively indicate that the differences are significant at 5% and 1% levels of significance; biofert (+) = yield of barley crop following faba bean with biofertilizer and biofert (-) = without biofertilizer. agricultural system sustainability is the paradigm of present-day planning or decision making with a very broad concept that cannot be defined by simple terms but should be guided by multiplicity of its use (pennell and schilizzi, 1999). nevertheless, sustainable agriculture involves management of resources to satisfy increasing needs while maintaining or enhancing the quality of the environment as well as conserving natural resources. sustainability is, therefore, the combination of all agricultural practices helping to increase crop productivity with low use of chemical inputs and labor while maintaining the environment, human and animal health (mohammadi and sohrabi, 2012). such improvements include increasing production efficiency at given levels of inputs and consequently reduce input levels to achieve same yield. in the present context, therefore, sustainability is viewed from a standpoint that the potential microbial inoculants have to increase crop production and productivity through utilization of atmospheric nitrogen rather than using chemical nitrogen fertilizer. farmers at lemu bilbilo woreda revealed that because of significant increases in yields of faba bean due to application of biofertilizer, coupled with competitive market prices, they are now encouraged to increase the land they allot to growing the crop. this has reportedly enabled them to match crop fields of cereals and pulses to practise effective crop rotation. furthermore, the farmers also evidently realized that repetitive cultivation of pulse crops with biofertilizer has improved the fertility and organic matter content of the soil and thus are convinced to stop fallowing as a means of soil fertility restoration. they also pointed that, earlier, they were able to grow faba bean only on relatively fertile soils rich in organic matter. however, they indicated that it is now possible for them to grow the crop even on less fertile fields using biofertilizer. the farmers also noted that the application of biofertilizer enhanced both plumpness and increased faba bean seed size in addition to increased yields of the crop as described above. they further hinted that plump seeds need less time to cook since they can absorb more moisture. this has a significant implication for saving cooking energy (use of less biomass as fuel especially cow dung) and the prospect of having spare organic matter for return to the land for soil and nutrient recycling. in the group discussions, the farmers repeatedly indicated that dap and urea have been used in the area since the mid-1960s. the farmers perceived that the soil is virtually exhausted, compelling them to continuously increase the rate of fertilizer over the nigussie alemayehu east african journal of sciences volume 14 (1) 1–12 10 years. the farmers revealed that they are currently using twice as much dap as recommended for wheat (up to 200 to 250 kg ha-1. after the introduction of biofertilizer, however, they found the soil became more fertile and richer in organic matter content. as a result, they indicated that the wheat stands following faba bean looked relatively more vigorous, demanding less additional nitrogen fertilizer. according to the woreda experts, earlier, faba bean production was almost impossible without using fungicides against fungal diseases. but with the use of biofertilizer, the need for using the chemicals diminished as the incidence of the disease reduced. less use of fungicides has obviously a positive contribution to environmental as well as economic sustainability. a body of literature supports this perception of farmers where biofertilizers can make plants tolerant to adverse environmental stresses including diseases (bhattacharjee and dey, 2014). the authors inferred that proper use of biofertilizers not only had impact on sustainable agriculture but also contributed to a sustainable ecosystem and wellbeing of farmers and consumers alike. likewise, monika et al. (2018) and mohammadi and sohrabi (2012) asserted that biofertilizers would generally play key roles in improving crop productivity and maintaining soil fertility, threby enabling to achieve sustainable, economical, and environmentally friendly farming. 4. conclusions this study has demonstrated that the use of biofertilizer (seed inoculation with rhizobium bacteria) by smallholder farmers resulted in significantly higher yields of faba bean and subsequently grown wheat and barley in a rotation system in four kebeles of lemu bilbilo and digelu tijo districts (woredas) of arsi zone. smallholder farmers who ioculated faba bean seed with rhizobium gained the benefit of relative seed yield increases amounting to 79%, 66%, and 42% for faba bean, wheat, and barley, respectively, in the rotataion system, over smallholdwer farmers who used uninoculated faba bean seeds. in addition to the yield gains, a list of other benefits contributing to system sustainability were recognized by farmers that inoculated seed of faba bean with rhizobium before planting. these benefits included improved soil fertility, partly as a result of the prospect of return of more organic matter into the soil, less need to use miner fertilizers for growing cereals subsequent to growing faba bean. rhizobium-inoculated faba bean was also reported to be more tolerant to fungal diseases and required less use of fungicide. the biofertilizer enhanced plumpness and increased seed size of faba bean which would absorb more water and cook faster, requiring less biomass energy. with the introduction of the biofertilizer, farmers indicated that they were able to grow faba bean on less fertile land, which was difficult before. rotation of cereals with pulse crops to restore soil fertility has been practiced by ethiopian farmers and the advantages have long been realized. in view of making the best use of the biofertilizer and maximize economic and environmental benefits, there are areas that need further research. research is needed to fully assess how exactly biofertilizer contributes to the yield of cereal crops that are planted following cultivation of faba bean onoculated with rhizobium and quantify the amount of nitrogen left behind after harvesting the faba bean. research also is neede to generate quantitative data not only on the biological but also the ecological and economic benefits of biofertilizer. future research should also provide explicit evidence to elucidate the limitations associated with long cycles of cereal monoculture and also refine or redefine the virtues and advantages of incorporating rhizobiainoculated pulse crops in the rotation system to anchor sustainability of the farming system in general. the results of this study imply that there is a strong need to scale up the use of biofertilizer by strengthening technology multiplication and the public extension system. the increased involvement of private sectors and cooperative unions in production, distribution, and marketing of quality biofertilizer is also essential in such efforts. 5. acknowledgements the author wishes to thank the agriculture knowledge, learning, documentation and policy (akldp) project for logistical and financial support needed to conduct the assessment. thanks are also due to dr. amare tadesse (kulumsa agricultural research center) for guiding and facilitating the link with the agriculture offices and farmers of the woredas that took part in the study. the professional assistance received from mr. demeke nigussie (eiar) in compiling the geoclimatic data and mapping the assessment areas is duly acknowledged. an utmost gratitude is due to the farmers, development agents (das), woreda experts and local leaders in the study areas for sparing their time and energy to provide the important information and perspectives on the use of biofertilizer. 6. references abendroth, l.j., elmore, r.w. and ferguson, r.b. 2006. g06-1622 soybean inoculation: applying the facts to your fields 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ernest, s., tolera, d., dagne, w. and henok, k. 2015. effect of faba bean break crop and n rates on subsequent grain yield and nitrogen use efficiency of highland maize varieties in toke kutaye, western ethiopia. american journal of research communication, 3: 200–210. tsegaye, t. 1992. vertisols of the centeral highlands, ethiopia – characterization, classification and evaluation of the phosphorus status. m.sc. thesis, alemaya university of agriculture, ethiopia. http://www.iiste.org/ https://doi.org/10.3389/fmicb.2018.01909 microsoft word paper-7(proof revised) final.docx ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (1) 83-94 licensed under a creative commons *corresponding author: e-mail: aseid2651@gmail.com attribution-non-commercial 4.0 international license. effect of replacing maize (zea mays) with barley (hordeum vulgare) on broilers performance and carcass characteristics seid ali a*, negassi amha b and mengistu urge b a school of animal and range sciences, hawassa university, p.o. box 5, hawassa, ethiopia b school of animal and range sciences, haramaya university, p.o. box 138, dire dawa, ethiopia abstract: a study was conducted to investigate the effect of feeding barley as a replacement for maize on the growth performance and carcass characteristics of cobb 500 broiler chickens. one hundred and sixty-eight day old chicks were randomly assigned to four treatment diets with three replicates, having 14 chicks in each replication, in a completely randomized design. the treatment diets were maize 100% (t1) and maize substituted with barley at 33.3% (t2), 66.7% (t3) and 100% (t4). similar amount of concentrate mix was added to all treatments. the experiment was conducted for a total of 56 days, with the first 121 days being the starter phase and the finisher phase lasted up to 56 days following the end of the starter phase. feeds offered and refused was recorded every day, while body weight was recorded on a weekly basis. at the end of the experiment, two chickens from each sex were slaughtered per replication to evaluate the carcass components. the current results indicated higher crude protein, ash and crude fiber contents in barley than maize, while higher energy content was obtained from maize compared to barley. starter phase diets gave similar feed intake values among treatments (36.8 38.8 g/day), showing a gradually decreasing trend with increasing levels of barley. weight gains, growth rate and feed conversion ratio were similar up to 66.7% of maize replaced with barley. at finisher phase, daily feed intakes were 134.0-142.3 g with daily gains of 40.4-51.7g. for total period, daily feed intakes were 97.8-103.5 g with daily gains ranged from 31.2-38.8 g. chicken under t1, t2 and t3 showed similar values of feed intake and growth performance in the finisher and total feeding periods. carcass yield was also similar for t1, t2 and t3. in conclusion, barley could be used as an alternative source of energy in broiler nutrition by replacing 2/3rd of the maize, especially in areas where maize is not available or less productive or where its price is high. keywords: cobb 500; feed conversion ratio; feed intake; growth performance; weight gain. 1. introduction the current world population of 7.6 billion is estimated to reach 8.6 billion in 2030, 9.8 billion in 2050 and 11.2 billion in 2100, according to the united nations reports of 2017 (un, 2017). driven by population and economic growth, worldwide demand for meat consumption is predicted to increase by 60-70% in 2050 while poultry meat represents around 36% of this global meat production (makkar et al., 2014). broiler production is fundamental for rapid and sustainable production of the highly demanded animal source protein in developing countries (raji et al., 2014). mahmoudnia and madani (2012) reported that broiler production has increased rapidly in tropical and subtropical regions in the past and sustained growth are forecasted for the future. however, feed supply and price are the major challenges of the poultry sector in developing countries including ethiopia. it had been reported that feed expense accounts up to 70% of total cost in commercial poultry production (hunduma et al., 2010) and energy and amino acids account for more than 90% of this cost (jayaprakash et al., 2016). although several researches had been conducting to alleviate feed shortage and price, still further efforts are needed to exploit alternative feedstuffs that can meet the nutrient requirements of poultry (hunduma et al., 2010). the principal energy source in broiler diets are cereal grains particularly maize, which remains the sole energy source in most poultry diets. this is due to the fact that the ratio of available energy to gross energy is higher for maize than other cereals because of its high starch and crude fat content (mcdonald, 2010). in ethiopia, maize is a common warm weather cereal crop widely growing between 1500 and 2200 meter above sea level (m.a.s.l.), with a yield of 3.7 t/ha (csa, 2017). among the major cereals, maize is the most important staple in terms of calorie intake in rural ethiopia. the 2004/5 seid et al. east african journal of sciences volume 14 (1) 83-92 84 national survey of consumption expenditure indicated that maize accounted for 16.7% of the national calorie intake followed by sorghum (14.1%) and wheat (12.6%) in descending order (berhane et al., 2011). although maize is produced throughout the world, there was stiff competition among human, livestock and industry (ajebu et al., 2016). these stiff competitions for multiple uses, more than ever the current alternative use of maize for bio-fuel production, would increase maize price in the future; such that any increase in its price will radically affect the price of broiler feeds, especially in maize importing countries. to this effect, investigation of some potential feed resources that are locally available with better comparative nutritional value as energy sources like barely in broiler diets would be justifiable. barley (hordeum vulgare l.) is the predominant cereal in the highlands of ethiopia with an optimum altitude range of 2000 to 3500 masl and covers 14.65% of the land under crop cultivation, with a yield of 2.1 t/ha (csa, 2017). the total yield of barley has been increased by 4.99% between 2013/2014 and 2014/2015 and also by 5.2% in the year 2015/2016 (csa, 2017). barley had an extensive root system that makes it able to compete with weeds and often used to break disease, insect and weed cycles associated with other crops (karley et al., 2011). it also had higher photosynthetic activity than other cereals, which implies the level of nitrogen fertilizer used for barley production was typically lower than that for maize (karley et al., 2011). moreover, barley contains more protein and better amino acid profile than maize, which implies barley-based diets require less protein supplementation (sadeghi and habibian, 2016). although barley is well known to tolerate frost periods and grown successfully in highland areas where maize is less productive with lower price (75% of that of maize in local markets), the use of barley in poultry diets is not well documented under the ethiopian condition. the current study was thus designed to evaluate the nutritional potential of locally available barley as alternative energy source on growth performance and carcass components by substituting maize in concentrate-based diets of cobb 500 broiler chickens reared under tropical environment. 2. materials and methods 2.1. study site the experiment was conducted at agarfa a-tvet college poultry farm, located 458 km south east of the capital city, addis ababa. it falls between 717'n latitude and 3949'e longitude with an average altitude of 2000 masl. the mean annual temperature of the district is 17.5°c. the minimum and maximum temperature are 10°c and 25°c, respectively. the average annual rainfall is 800 ml, whereas 400 ml and 1200 ml were the minimum and maximum rainfall recorded in the agarfa district, respectively. barley and wheat are the dominant cereal crops cultivated in the area. 2.2. experimental design the study was a one-factor experiment in a completely randomized design (crd) with four dietary treatments each replicated three times. in the control diet (t1) maize was served as the main energy source without barley grain inclusion and in the rest of the treatments maize was substituted by barley (represented hereafter as t2, t3 and t4) weight by weight at 33.3%, 66.7% and 100%. the levels of barley in treatments (t2, t3 and to t4) were 11%, 22% and 33% for the first three weeks of age and 14.5%, 29% and 43.5% for the finishing period of 22 to 56 days. one hundred and sixty eight (168) day old unsexed cobb 500 broiler chicks were randomly assigned to the four treatment diets with three replicates having 14 chicks per replication. the total experimental period took 56 days. the layout of the experiment is shown in table-1. table 1. layout of the experiment. treatments barley substitution level (%) maize (%) replicates number of chicks per replicate number of chicks per treatment t1 0 100 3 14 42 t2 33.3 66.7 3 14 42 t3 66.7 33.3 3 14 42 t4 100 0 3 14 42 2.3. ingredients of the experimental diets the experimental dietary rations were composed of maize (white), barley grain, wheat short, soybean meal, noug seed cake (guizotia abyssinica), limestone, dicalcium phosphate (dcp), vitamin premix, common salt, lysine and methionine. a single batch of barley and maize were purchased from local market, whereas the rest feed ingredients were purchased from kality animal feed enterprise, addis ababa, ethiopia. all ingredients, except vitamin premix and limiting amino acids, were milled to pass through a 5 mm sieve size. all ingredients were then mixed according to the formulated experimental diets (table 2) to meet the standard nutrient requirements of broilers as outlined seid et al. replacing maize with barley on broilers performance 85 by nrc (1994). moreover, representative samples from each treatment diets were taken for the determination of chemical compositions. table 2. proportion of feed ingredients used to formulate the starter and finisher broiler chicken rations per 100 kg (as feed bases). feed ingredients treatments t1 t2 t3 t4 starter ration maize (white) 33 22 11 0 barley 0 11 22 33 concentrate mix a 67 67 67 67 total 100 100 100 100 finisher ration maize (white) 43.5 29 14.5 0 barley 0 14.5 29 43.5 concentrate mix b 56.5 56.5 56.5 56.5 total 100 100 100 100 note: a nsc (noug seed cake) = 26.7, sbm (soy bean meal) = 20.3, dcp (di-calcium phosphate) = 0.75, wheat short = 17, limestone = 0.9, vitamin premix = 0.5, common salt = 0.25, lysine = 0.35, methionine = 0.25; b nsc (noug seed cake) = 24.4, sbm (soy bean meal) =11.5, dcp (di-calcium phosphate) = 0.75, wheat short =17.6, limestone = 1, vitamin premix = 0.5, common salt = 0.25, lysine = 0.25, methionine = 0.25; t1 = 100% maize (0% barley); t2 = 33.3% of maize replaced with barley; t3 = 66.7% of maize replaced with barley; t4 = 100% of maize replaced with barley. 2.4. management of experimental chickens 2.4.1. housing the broilers the deep litter experimental house was wire-mesh partitioned in to 12 pens of 1.5 m x 2 m dimensions having a space of 0.5 m between pens and providing sufficient space for finisher birds. the experimental pens were thoroughly prepared, cleaned, disinfected and equipped 15 days before arrival of chicks. the pens were fumigated with formaldehyde gas of 20 g of potassium per manganet (kmno4) powder plus 100 ml of 37% formaline per m3 of space. the floor was covered with disinfected sawdust having 4-5 cm depth. the temperature of the experimental house and brooding appliances were adjusted 24 hours before chick’s arrival and a careful pre-placement management of feeders and drinkers for each pen; placement of drinkers close to the feeders, but not so close as to cause feed spoilage. 2.4.2. brooding and health management a total of 168 day-old unsexed cobb 500 broiler chicks were purchased from alema farms plc, debre zeit, ethiopia. the chicks were then randomly assigned into 12 pens and reared under brooder for four weeks. about 60 watt infra – red lamps were switched on to provide warmth. the initial temperature of the pen was 35°c which was reduced sequentially based on the chick's age until reaching 21c at day twenty eight. as a bio-security measure, a disinfectant (10% of 37% formaline) was used as footbath on all entrances. litter was raked frequently to allow good air circulation. functionality of drinkers were checked regularly. all chicks were vaccinated against marek's (day 1), newcastle (day 7 and 21) and infectious bursal diseases (day 14 and 28) as recommended by the veterinarian and mortality was recorded daily. the general health of the chicks and sanitary measures were closely monitored. 2.4.3. feeding and data collection measured amount of feed was offered twice a day (8:30 and 17:30) per pen and refusals were weighed and recorded every day at 8:00 before the daily feed offered. fresh clean water was provided ad libitum. chicks were fed starter ration for the first three weeks followed by finisher ration till the 8th week. feed intake was calculated for the same periods and feed conversion ratio was calculated after adjusting feed intake for mortality. requirements for the starter and finisher phases of chicks were estimated at 0.80 kg and 4.89 kg of feed per chick, respectively. chicks were weighed on a pen basis initially and every week afterwards before morning meal. finally, growth rate was calculated using the equation of larner and asundson (1932) as gr = ((lbw2 lbw1) × 100)/ (0.5 (lbw1 + lbw2)). the feed or protein conversion ratio was calculated from the total feed or protein consumed by chicks per unit of body weight gain. at the end of the eighth week, two chicks from each sex close to mean weight were selected per pen. after withholding of feed overnight, each bird was weighed (considered as pre-slaughter weight), humanely slaughtered by severing the jugular vein, allowed to bleed completely and manually eviscerated. the carcass cuts, abdominal fat, edible and non-edible offal components were weighed and recorded. carcass dressing percentage (cdp) was seid et al. east african journal of sciences volume 14 (1) 83-94 86 calculated as: (carcass weight/pre-slaughter weight) × 100%. 2.5. chemical analysis of feeds dry matter, ether extract, crude fiber, crude protein and crude ash were determined following method of aoac (1995). crude protein was computed by multiplying n concentration by 6.25. metabolizable energy was calculated by indirect method of wiseman (1987) as: me (kcal/kg dm) = 3951 + 54.4 ee 88.7cf 40.8 ash. all samples were analyzed in duplicates at animal nutrition laboratory of haramaya university. 2.6. statistical analysis data were analyzed using general linear model (glm) procedures of statistical analysis system (sas, 2008). treatment means were compared using duncan's multiple range test at p<0.01. the model used was: yij = μ + ti + eij where, yij = dependent variable; μ = overall mean; ti = effect of the ith treatment diet/ feeding level/sex; eij = effect of the random error. 3. results 3.1. chemical composition of feed ingredients the results of laboratory analysis for the major feed ingredients used in the formulation of experimental rations are presented in table 3. the chemical analysis results of the current study revealed that dm, cp, cf and crude ash contents of barley grain were found to be higher compared to maize grain with nfe, ee and me being slightly lower in barley grain. table 3. chemical composition and energy content of feed ingredients. ingredients chemical composition a dm (%) cp (%) ee (%) cf (%) ash (%) nfe (%) me (kcal/kg dm) maize (white) 90.8 9.8 3.4 2.7 2.7 72.2 3742 raw barley 91.4 11.8 2.5 5.3 3.1 68.7 3490 wheat short 92.4 17.5 4.3 8.3 4.1 58.2 3281 nsc 93.2 32.8 9.8 17.1 9.2 24.3 2604 sbm 93.8 37.6 10.4 6.3 6.2 33.3 3668 note: a nsc = noug seed cake; sbm = soya bean meal; dm = dry mater; cp = crude protein; ee = ether extract; cf = crude fiber; me = metabolizable energy; nfe = nitrogen free extract = dm (cp + ee + cf + ash); and kcal = kilocalorie. 3.2. chemical composition of experimental diets the results of laboratory analysis for the starter and finisher treatment diets are given in table 4. the dm, cp, cf and ash levels of the starters and finishers rations showed a slight increase as the inclusion level of barley grain increased while the me, ee and nfe content slightly decreased as inclusion level of barley grain increased. table 4. chemical composition of treatment diets containing different levels of barley as replacement for maize. treatment rations chemical composition a dm (%) cp (%) ee (%) cf (%) ash (%) nfe (%) me (kcal/kg dm) starter rations t1 92.6 23.1 6.58 8.31 5.30 49.3 3252 t2 92.6 23.3 6.48 8.54 5.35 49.0 3224 t3 92.7 23.5 6.38 8.77 5.39 48.6 3196 t4 92.8 23.7 6.28 9.00 5.44 48.3 3169 finisher rations t1 92.3 20.1 5.82 7.75 4.85 53.8 3278 t2 92.3 20.3 5.69 8.05 4.91 53.4 3241 t3 92.4 20.6 5.56 8.36 4.97 52.9 3205 t4 92.5 20.9 5.43 8.66 5.03 52.5 3168 note: a dm = dry mater; cp = crude protein; ee = ether extract; cf = crude fiber; me = metabolizable energy; nfe = nitrogen free extract; t1 = 100% maize (0% barley); t2 = 33.3% of maize replaced with barley; t3 = 66.7% of maize replaced with barley; t4 = 100% of maize replaced with barley. 3.3. nutrient and energy intakes of broilers the nutrient and metabolizable energy intakes of the experimental chicks are given in table 5, 6 and 7. the feed, dry matter, ether extract and metabolizable energy intakes of experimental chicks showed a linear decrease with increasing levels of barley in the diets at all stages. however, fiber intakes of chicks were significantly higher for diets t3 followed by t4. for the first three seid et al. replacing maize with barley on broilers performance 87 weeks, chicks under sole barley diet showed significantly (p<0.01) lower dietary protein intake. chicks fed diets of up to 66.7% maize replaced by barley took more dietary protein. chicks under sole barley diet (t4) showed a significant decrease in feed/dry matter, ether extract and energy intake at all stages. table 5. effect of barley replacement for maize on feed and nutrient (g/day) intakes of broilers for the starter phase (121d). intakes treatments t1 t2 t3 t4 sem p feed intake 38.82a 38.65a 38.06b 36.78c 0.24 <.0001 dry matter 35.94a 35.79a 35.28b 34.13c 0.22 <.0001 crude protein 8.97a 9.00a 8.94a 8.72b 0.03 <.0001 ether extract 2.55a 2.50b 2.43b 2.31d 0.03 <.0001 crude fiber 3.23c 3.30b 3.34a 3.31ab 0.01 <.0001 ash 2.057a 2.067a 2.051a 2.001b 0.01 <.0001 me (kcal/day) 116.89a 115.40b 112.75c 108.16d 1.00 <.0001 note: means in the same row without common letter(s) are significantly different at p<0.01 level of significance. table 6. feed and nutrient (g/day) intakes of broilers for the finisher phase (22-56d). intakes treatments t1 t2 t3 t4 sem p feed intake 142.33a 141.81a 139.94b 134.40c 0.95 <.0001 dry matter 131.37a 130.89a 129.30b 124.32c 0.84 <.0001 crude protein 28.61b 28.79a 28.83a 28.09c 0.09 <.0001 ether extract 8.28a 8.07b 7.78c 7.30d 0.11 <.0001 crude fiber 11.03d 11.42c 11.70a 11.64b 0.08 <.0001 ash 6.90b 6.96a 6.95a 6.76c 0.02 <.0001 me (kcal/day) 430.62a 424.22b 414.41c 393.84d 4.20 <.0001 note: means in the same row without common letter(s) are significantly different at p<0.01 level of significance. table 7. feed and nutrient (g/day) intakes of broilers for the overall period (1-56d). intakes treatments a t1 t2 t3 t4 sem p feed intake 103.51a 103.13a 101.73b 97.79c 0.68 <.0001 dry matter 95.58a 95.23a 94.04b 90.50c 0.61 <.0001 crude protein 21.24b 21.37a 21.37a 20.82c 0.07 <.0001 ether extract 6.13a 5.98b 5.77c 5.43d 0.08 <.0001 crude fiber 8.10d 8.37c 8.56a 8.52b 0.05 <.0001 ash 5.10b 5.13a 5.12a 5.00c 0.02 <.0001 me (kcal/day) 312.97a 308.41b 301.29c 286.71d 3.00 <.0001 note: a sem = polled standard error of mean; me = metabolizable energy; t1 = 100% maize (0% barley); t2 = 33.3% of maize replaced with barley; t3 = 66.7% of maize replaced with barley; and t4 = 100% of maize replaced with barley. means in the same row without common letter(s) are significantly different at p<0.01 level of significance. 3.4. effect of substituting maize for barley on body-weight changes the body weight changes of chicken at different ages are shown in table 8, 9 and 10. there was no significant (p>0.01) difference in body weight among treatment groups at the start of the experimental period. the substitution of maize with barley resulted in reduction of body weight gain and growth performance of chicks, with increasing levels of barley in treatment diets. in the first 21 days, chicken under sole barley diet showed poor performance compared to chicken under sole maize diet. similar patterns were also observed for the finisher phase. seid et al. east african journal of sciences volume 14 (1) 83-94 88 table 8. mean values for body weight changes of broilers for the starter phase (1-21d). parameters treatments a t1 t2 t3 t4 sem p initial body weight (g/h) 40.27 40.00 40.07 39.73 0.20 0.8677 final body weight (g/h) 402.50a 398.73a 398.27a 372.90b 3.64 <.0001 body weight gain (g/h) 362.23a 358.73a 358.20a 333.17b 3.59 <.0001 average daily gain (g/h) 17.25a 17.08a 17.06a 15.87b 0.17 <.0001 growth rate, % 163.62a 163.54a 163.44a 161.48b 0.32 0.0141 note: a sem = polled standard error of mean; t1 = 100% maize (0% barley); t2 = 33.3% of maize replaced with barley; t3 = 66.7% of maize replaced with barley; and t4 = 100% of maize replaced with barley. means in the same row without common letter(s) are significantly different at p<0.01 level of significance. table 9. mean values for body weight changes of broilers for the finisher phase (22-56d). parameters treatments a t1 t2 t3 t4 sem p initial body weight (g/h) 402.50a 398.73a 398.27a 372.90b 3.64 <.0001 final body weight (g/h) 2213.47a 2161.53a 2049.13a 1785.93b 52.66 0.0003 body weight gain (g/h) 1810.97a 1762.80a 1650.87a 1413.03b 49.42 0.0005 average daily gain (g/h) 51.74a 50.37a 47.17a 40.37b 1.41 0.0005 growth rate, % 138.38a 137.69a 134.89ab 130.89b 0.99 0.003 note: a sem = polled standard error of mean; t1 = 100% maize (0% barley); t2 = 33.3% of maize replaced with barley; t3 = 66.7% of maize replaced with barley; and t4 = 100% of maize replaced with barley. means in the same row without common letter(s) are significantly different at p<0.01 level of significance. table 10. mean values for body weight changes of broilers for the overall period (1-56d). parameters treatments a t1 t2 t3 t4 sem p initial body weight (g/h) 40.27 40.00 40.07 39.73 0.20 0.8677 final body weight (g/h) 2213.47a 2161.53a 2049.13a 1785.93b 52.66 0.0003 body weight gain (g/h) 2173.20a 2121.53a 2009.07a 1746.20b 52.60 0.0003 average daily gain (g/h) 38.81a 37.89a 35.88a 31.18b 0.94 0.0003 growth rate, % 192.84a 192.73a 192.33a 191.29b 0.20 0.0005 note: a sem = polled standard error of mean; t1 = 100% maize (0% barley); t2 = 33.3% of maize replaced with barley; t3 = 66.7% of maize replaced with barley; and t4 = 100% of maize replaced with barley. means in the same row without common letter(s) are significantly different at p<0.01 level of significance. 3.5. effect of substitution on feed conversion ratio the feed conversion ratios and mortality rates of chicken at different ages are shown in table 11. the feed and protein conversion ratios expressed as g feed per g weight gain and cp per g weight gain, respectively, were increased with increasing levels of barley at different ages. the total replacement of maize with barley (t4) resulted in significantly (p<0.01) higher feed and protein conversion ratio for the first 21 days of the experiment. similar pattern was observed for the finisher phase and whole experiment. the overall mortality rate in the entire experimental period was 10.12% with 7.74% and 2.38% for the starter and finisher phases, respectively. most of the mortality occurred (84%) during the first 10 days of the trial and was not related to treatments. the similar in mortality among treatment groups might indicate optimum balance of nutrients in maize and barley diets. seid et al. replacing maize with barley on broilers performance 89 table 11. mean values for feed and protein conversion ratios and mortality rate of broilers. parameters a treatments b t1 t2 t3 t4 sem p starter phase (1-21d) fcr 2.25ab 2.26ab 2.23b 2.32a 0.0122 0.0294 pcr 0.52b 0.53b 0.52b 0.55a 0.0038 0.0031 m 7.14 7.14 9.52 7.14 1.3785 0.9314 finisher phase (22-56d) fcr 2.76b 2.82b 2.97b 3.33a 0.07 0.0018 pcr 0.55b 0.57b 0.61b 0.70a 0.02 0.0005 m 2.56 5.81 0.00 2.78 1.19 0.4442 overall period (1-56d) fcr 2.67b 2.72b 2.84b 3.14a 0.06 0.0018 pcr 0.55b 0.56b 0.60b 0.67a 0.01 0.0005 m (%) 9.52 11.91 9.52 9.52 1.38 0.9314 note: a fcr = feed conversion ratio; pcr = protein conversion ratio; and m = mortality. b sem = polled standard error of mean; t1 = 100% maize (0% barley); t2 = 33.3% of maize replaced with barley; t3 = 66.7% of maize replaced with barley; and t4 = 100% of maize replaced with barley. means in the same row without common letter(s) are significantly different at p<0.01 level of significance. 3.6. effect of substitution and sex on carcass parameters in the current study, significant difference (p>0.01) were not observed in carcass yield and organ weights among chicken under t1, t2 and t3 treatments (table 12). however, t4 showed the least values on most of carcass parameters including weight at slaughter, carcass weight, commercial carcass, drumsticks, breast, wing, gizzard, dressing percentage based on carcass cdp and tneo weights. the carcass yield analysis revealed significantly (p<0.01) higher back bone and af accumulation values for t1 and t3, respectively. regarding sex effects, male broilers showed significantly higher values of cdp, cc, thighs and neck compared to female counterparts. on the other hand, both sexes showed similar values for other edible and non-edible carcasses components. table 12. mean values for carcass yield and organ weights in 56-day old cobb 500 broilers (g). parameters a sex treatments b male female t1 t2 t3 t4 sem p slwt 2220.42 2103.75 2258.17a 2223.83a 2210.67a 1955.17b 34.64 0.0015 neck 62.73 59.17 62.37 62.92 59.45 59.07 0.92 0.3428 wings 86.16a 74.15b 80.67 82.13 86.57 71.25 2.05 0.0460 drumsticks 227.47 199.14 216.62a 223.53a 235.25a 177.82b 6.11 0.0012 thighs 254.94a 217.73b 245.57 238.75 245.95 215.08 5.64 0.1716 breast part 615.55 567.28 617.98a 608.33a 599.37ab 539.98b 9.82 0.0115 back bone 123.51 120.30 150.00a 120.90b 118.75b 97.97b 4.90 0.0002 liver 50.92 46.94 50.25 50.90 49.75 44.82 0.88 0.0459 gizzard 48.44 45.15 50.32a 46.55a 48.75a 41.57b 0.87 0.0002 skin 104.26 112.73 130.02a 110.55b 104.18b 89.25c 3.42 <.0001 af 11.81 9.54 11.68b 8.98bc 17.95a 4.08c 1.25 <.0001 teo 203.63 204.82 230.58a 208.00b 202.68b 175.63c 4.54 <.0001 tneo 566.37 550.68 580.42a 575.02a 579.82a 498.85b 10.66 0.0059 cc 1370.36a 1237.78b 1373.20a 1336.57a 1345.33a 1161.17b 26.54 0.0091 cwt 1573.99 1442.59 1603.78a 1544.57a 1548.02a 1336.80b 29.83 0.0024 cdp 70.84a 68.50b 70.92 69.44 69.99 68.34 0.37 0.0897 note: a slwt = slaughter weight; af = abdominal fat; teo = total edible offal (liver, gizzard and skin); tneo = total nonedible offals; cc = commercial carcass (thighs, drumsticks, breast part, backbone, neck and wings); cwt = carcass weight (cc and teo); and cdp = carcass dressing percentage. b sem = polled standard error of mean; t1 = 100% maize (0% barley); t2 = 33.3% of maize replaced with barley; t3 = 66.7% of maize replaced with barley; and t4 = 100% of maize replaced with barley. means in the same row without common letter(s) are significantly different at p<0.01 level of significance. seid et al. east african journal of sciences volume 14 (1) 83-94 90 4. discussion 4.1. nutrient and energy intakes in this study, sole barley diets decreased feed and dry matter intakes of broilers at different phases of the experiment. a similar study of friesen et al. (1992) showed a reduction in feed intake by using 35% and 70% barley in broiler diets. jacob and pescatore (2012) also reviewed that increasing levels of untreated barley reduced feed intake of broilers. the lower feed intake of broilers, especially young chicks, fed barley-based diets might be attributed to the detrimental effects of the non-starch polysaccharides, especially β-glucans found in barley grain (gracia et al., 2003; onderci et al., 2008). the β-glucans form gels in the bird digestive tract are not broken down because of the lack of appropriate enzymes and the rapid rate of passage in poultry (sadeghi and habibian, 2016). in addition to the limited enzyme production, slow gastrointestinal transit of digesta may reduce feed intake and growth (gracia et al., 2003). the reduced voluntary feed intake could also be associated with poor palatability of the feed due to barley, which has higher crude fiber content compared to maize. it had been reported that dietary factors, including energy density, deficiency or excessness of nutrient such as carbohydrates, proteins and minerals can also influence feed intake in poultry (mbajiorgu et al., 2011). in contrast to the current finding, veldkamp et al. (2005) reported that as dietary energy level increased; broiler chickens satisfy their energy needs by decreasing feed intake. in the current study, the protein, fiber and ash intakes of chicks showed a linear increase with the increasing levels of barley in the treatment diets, which might be attributed to the combination of higher dry matter intake of chickens and the relatively higher protein, fiber and ash contents of barley-based diets. the crude fiber content of the experimental diets varied between 7.75% and 8.66% which is slightly above the maximum cf (7%) requirement of broiler diets (varastegani and dahlan, 2014). according to saki et al. (2010), fiber can be included in broiler diets to reduce fat deposits and produce lean meat. melkamu (2013) also reported the advantage of crude fiber in improving dm intake of chicken by increasing fecal bulk and speed up the passage rate of feed through the digestive tract which keep the health of gastrointestinal tract. likewise, the trend of reduction of metabolizable energy and ee intakes of broilers fed barley-based diets might be attributed to the low feed intake and low oil content of barley diets. the lipid content of barley is relatively low, only 2 to 3% of the grain (sadeghi and habibian, 2016). this, together with high fiber and ash intakes seems to have contributed to the differences in metabolizable energy intake of broilers. it had been reported that the level of inclusion of barley is limited because of its lower metabolizable energy and negative effects on bird performance (onderci et al., 2008). the addition of fat to poultry diets that rely on barley could thus be another possible explanation, as indicated previously by sadeghi and habibian (2016). 4.2. body-weight changes and growth performance in the current study, the final body weight of broilers ranged from 1785.9 g to 2213.5 g at 56 days of age. similarly sadeghi and habibian (2016) reported 2000 to 2100 g for broilers fed barley-based diets with or without enzyme supplementation. however, a study of abera et al. (2018) showed 22032600 g for cobb 500 broilers reared at agarfa poultry farm. the average daily gain of 31.2 to 38.8 g also agreed with 40.8 to 42.9g reported by sadeghi and habibian (2016) but less than the 47.1 to 57.1 g results obtained by abera et al. (2018). the differences might be due to the differences in nutritional content of the diet, management of birds or the conditions under which the experiment was carried out (rebolé et al., 2010). any variation in the environment surrounding the birds resulted in stunted growth and major productive losses (czarick and fairchild, 2012). the comparable weight gain and growth of broilers fed sole maize and broilers fed maize/barley diets was consistent with the results obtained by bennett et al. (2002) and sadeghi and habibian (2016). it has been reported that broilers can fed up to 35% barley with no overall effects on bird performance (bennett et al., 2002). sadeghi and habibian (2016) observed comparable growth with barley replacement up to 50% of maize in starter diets and up to 100% for older broilers. however, jacob and pescatore (2012) did not recommend the inclusion of untreated barley grain, especially in starter broiler diets. on the other hand, the reduction of body weight changes of broilers fed sole barley diets (t4) was consistent with previous reports (mansoori et al., 2011; ribeiro et al., 2012). it has been reported that feeding high barley diets decreased body weight gain (mansoori et al., 2011; ribeiro et al., 2012). according to shakouri et al. (2009), the negative effects of barley on the growth performance of broiler chickens could be related to the altered intestinal morphology, endogenous enzyme activity and gut microflora. it might also be due to shortening, thickening, and atrophy of the villi as well as increase in the number and size of goblet cells as suggested by onderci et al. (2008). 4.3. feed conversion ratio in the current study, the feed conversion ratios (ranged from 2.67 to 3.14) were better than values of 3.19 to 3.41 reported by ajebu et al. (2016) for cobb 500 broilers. feed conversion ratios of 2.08 to 2.44 were obtained by abera et al. (2018) while sadeghi and habibian (2016) reported 1.73 to 2.5 in cockerels fed barley-based diets. the differences might be due to seid et al. replacing maize with barley on broilers performance 91 barley type or the conditions under which the experiment was carried out (rebolé et al., 2010). in the current study, feed conversion ratio of broilers were comparable between broilers fed maize-based diet and broilers fed diets of up to 66.7% of maize substituted with barley. similar confirmation of the suitability of barley was established by the work of mansoori et al. (2011), who observed absence of feed efficiency changes on broiler diet containing 30% barley. the increasing trend of feed conversion ratio figures with increasing levels of barley in the current study agreed with the reports of onderci et al. (2008), shirzadi et al. (2009) and sadeghi and habibian (2016) who observed increased feed conversion ratio by feeding high barley diets. a similar trend was reported by bennett et al. (2002) who observed a temporary loss in early growth and feed conversion efficiency when barley was included at any level above 5% in broiler diets. however, the current finding was not in agreement with the work of ribeiro et al. (2012) who observed a decreased feed conversion ratio when poultry were fed with high barley diets. 4.4. carcass characteristics the similarity in primal carcass parts of broilers fed sole maize and broilers fed maize/barley diets in the current study was consistent with previous reports (melkamu, 2013; raji et al., 2014). it was reported by several authors that carcass yields were unresponsive to dietary me level (melkamu, 2013; raji et al., 2014). etalem et al. (2013) reported significant differences on drumstick weight and drumstick percentage on hubbard broilers similar with the current study. the breast part and carcass yield were lower in broilers fed diet of 100% barley. similarly, moharrery (2006) reported a higher percentage of breast part and carcass yield in broilers fed diets containing 35% barley. the comparable gizzard weight of broilers fed on sole maize and those fed on maize/barley diets indicated presence of adequate energy for birds from those dietary treatments. similarly, the observed higher abdominal fat of broilers fed 66.7% of barley diet was in agreement with the findings of rabie et al. (2010) who observed accumulation of abdominal fat caused by low energy diets with the reasons being substantiated by the report of nikolova et al. (2007) who indicated abdominal fat being affected by genotype, sex, age and nutrition of the broilers. in the current study, male broiler chicks were significantly higher for cdp, cc, thighs, wing and neck compared to the females, which suggest the existence of association between these traits in both sexes to express them. this sex difference might be attributed to the presence of sex hormone (androgen) in males which enhanced muscle development compared to the sex hormone (estrogen) in females, mostly responsible for fat deposition rather than muscle tissue development (abera et al., 2018). on the other hand, in contrast with the findings of the current study, ajebu et al. (2016) reported heavier breast muscle for male chickens compared to females. 5. conclusions the effect of replacing maize with barley on feed intake, growth performance and carcass yield characteristics of cobb 500 broiler chickens was studied for 56 days. suitability of barley in concentratebased diets was successful to replace 2/3rd of maize in starter broiler diets. also at finisher phase sole barley diet resulted in poor performance of broilers. it is thus concluded that replacement of up to 66.7% of maize with barley will not adversely affect growth performance and carcass traits of broilers. the inclusion of barley up to the proportion of 30% of ration can be recommended for feeding of broilers, especially in areas where maize is not available or less productive or its price is high. 6. acknowledgements the authors are highly grateful to agarfa atvet college and niche project (niche/eth/178) for granting the research fund. the authors also acknowledge haramaya university on 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worth and c. ltd. seid et al. east african journal of sciences volume 14 (1) 83-94 94 ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (2) 121-130 licensed under a creative commons *corresponding author. e-mail: gachena2012@gmail.com attribution-noncommercial 4.0 international license. determinants of export performances of major spices (turmeric and korarima) in ethiopia dessalegn gachena1*, jema haji2, belayineh legesse2, and mengistu ketema2 1college of agriculture, department of agricultural economics, wolkite university, ethiopia 2school of agricultural economics and agribusiness, haramaya university, ethiopia abstract background: ethiopia has comparative advantages in the production of exportable spices due to existing rich genetic resources, diverse agro-ecological condition and abundant arable land and labour. however, despite their high potential and opportunities for export, most spices including turmeric and korarima are not fully utilized. objective: this study was intended to analyze the determinants of export performance of major spices (turmeric and korarima) in ethiopia. material and methods: the random effect gls gravity model was selected as an analytical tool to estimate the determinant of major spices export performance between ethiopia and nine sampled spices trade partners using annual panel data collected for a period of 2005 to 2015/2016. results: the results indicated that ethiopia's population, foreign direct investment, real exchange rate and institutional quality, the importers' gdp, gdp per capita and population, geographical distance and the dummy variables (comesa membership and sharing common borders) had significantly affected turmeric and korarima export performances, at different level of significance level, with their expected sign or effect. however, the variables intuitional quality and being comesa membership were found to have unexpected negative influences on the export performance of major spices (turmeric and korarima). conclusion: the finding of the study implied that there is a need to formulate policies and strategies that would promote institutional quality, improve supply capacity, attracting foreign direct investment, strengthen trade liberalization, deepening economic integration and targeting export destination that could reduce transportation costs in order to improve the export performance of those spices. keywords: export; gravity model; panel data; random effect; fixed effect model 1. introduction it is common to see fluctuations in the export income of countries mainly depending on the export of primary agricultural commodities. the problem is severe for countries like ethiopia that obtain a big share of their export income from a few agricultural commodities such as coffee, oilseeds, pulses, khat (catha edulis forsk) and live animals in which coffee alone accounted for about 34 percent of the value of all exports in 2017/2018 (eyayu, 2017). different empirical studies have shown that diversifying export bases towards high-value crops in general and spices, in particular, could increase export earnings and reduce economic risks depending on limited export items (moti, 2007; alekaw, 2016). despite its poor implementation, the agricultural commercialization strategy of ethiopia has realized underutilization of spices and the need for diversifying export thereby focusing on increasing production and productivity of spices (derese, 2009; mofed, 2010; mofed, 2016: eyayu, 2017). this implies that the spice subsector is within the framework of national agricultural policy which could facilitate further development of the subsector. spices are considered as high value and low volume agricultural commodities primarily used for flavor, color, aroma and preservation of food and beverages. the bulk of spices are exported in whole dried form, while only 15-20 percent of spices are sold in processed/grounded form as mixtures of ground spices and as essential oils and oleoresins characterizing them as a high-value product per unit weight. generally, in addition to household consumption, spices are becoming an important ingredient in food and beverage processing, pharmaceutical, and cosmetic and textile industries (nitesh, 2016; sharma et al., 2017). ethiopia has comparative advantages in the production of exportable spices due to its rich genetic resources, diverse agro-ecological condition and abundant arable land and labour. among 109 spices identified by the international organization for standardization (iso) about 50 valuable spices can be produced in ethiopia, particularly in the southwestern parts of the country. ginger, turmeric, korarima, red pepper, chili/hot peppers, black cumin, cardamom, and long pepper are the most widely grown spices in the country (addisu, 2014; girma et al., 2015; herms, 2015; mofed, 2016). the areas under spices crop cultivation have increased from 330,000 ha in 2005/2006 to 500,000 ha in the year 2013/2014. in the same years, the average dessalegn et al. east african journal of sciences volume 14 (2) 121-130 122 spice production has also improved from 238,000 to 418,000 tons in their dried weigh. according to ethiopian investment commission (eic, 2015), about five million smallholder farmers are already involved in spice production, and currently, the government is promoting and encouraging investment opportunities in the spice subsector. due to their multiple uses, there is a continuing and expanding international demand for spices in asia, middle east, africa, europe and the usa (addisu, 2014). particularly, the recognition of the medicinal properties of spices has spurred the demand for organic spices. according to addisu (2014), the global imports of spices is growing at an average annual growth rate of 10.2 percent and estimated at 85 billion usd in 2012. in this regard, ethiopia's proximity and strategic location to most of these spice importing countries would create a wide global market opportunity for spices trade. ethiopia is exporting dried spices such as turmeric, korarima, red and black pepper, cumin (black & white) and coriander to more than 38 destination markets thereby generating foreign currencies (addisu. 2014). according to some source, for example, the country has exported about 15,518 and 23,518 tons of dried spices with export values of 18.5 and 32 million usd in 2010 and 2012 respectively. despite their high economic potential and recent attention of the government in promoting the production and export of spices, the share of export revenue is yet one of the lowest in the total export earnings. on average spices, export constitutes 1.25 percent of the total export value of ethiopia. but, there has been a tendency of positive growth in the export of this commodity with an average rate of 53.9 percent for the period of 2010-2014 (herms, 2015; alekaw, 2016; abdu et al., 2017). this indicates that compared to other agricultural commodities the export potential of t spices has not been fully exploited. ethiopia’s export performance is said to be constrained by the real exchange rate, the distance between ethiopia and its partners, supply-side factors like real gdp, ethiopian institutional quality and trade policy and demand-side factors: such as population, partners' real gdp, and openness to trade (yishak, 2009 and tesfaye, 2014). the spices subsector is an important area for research since the production of high-value products is an emerging but poorly understood economic activity in ethiopia. most of the studies conducted previously have focused on the determinants of aggregated export performance in which the commodity-specific factors could not be identified (abdulaziz, 2009; alelign, 2014; alekaw, 2016; gebrehiwot, 2011; yishak, 2009;). analysis of export at a disaggregated level could enable policymakers to identify which sectors/commodities/products severely faced the supply capacity and foreign market access conditions. however, no empirical analysis has been undertaken regarding factors determining the export performance of spices separately in ethiopia. the core objective of this study was, therefore, to analyze the main determinant factors of supply-and demand-side of the two major spices ethiopia’s spices (turmeric and korarima) export performance using dynamic gravity models. the trade gravity model is the econometric model that often uses for ex-post analyses of international trade flows as a baseline model for estimating the impact of a variety of policy issues. it is based on the idea that overall trade volumes between the two nations depend on the size of the two nations and the distance they are apart. there are a couple of reasons for the central role played by the gravity model. the first has to do with its high explanatory power of on bilateral trade flows and enables us to incorporate dynamic effects among economies. the second reason is that it provides an easy method to test the role that other variables play in affecting trade (alemayehu, 2009). the importance of this paper is to fill the gap in the literature, as the issue of spices export performance has not been studied. therefore, understanding the performances of major spice export flows would help in guiding appropriate trade policies that could foster bilateral spice trade flows between ethiopia and its partners. 2. methodology 2.1. theoretical framework the trade gravity model is the econometric model that often use for ex-post analyses of international trade flows as a baseline model for estimating the impact of a variety of policy issues. it is based on the idea that overall trade volumes between the two nations depend on the size of the two nations and the distance they are apart. tinbergen and poyhonen were the first authors to developed gravity models of international trade. there are a couple of reasons for the central role played by the gravity model. the first has to do with its high explanatory power of on bilateral trade flows and enables us to incorporate dynamic effects among economies. the second reason is that it provides an easy method to test the role that other variables play in affecting trade (eyayu, 2017). the basic formulation of the gravity model explains bilateral trade flows in analogy to isaac newton‘s law of gravity, by the attraction of two countries’ masses (measured by gdp and/or population), reduced by the distance which is a proxy of transport costs and other factors. some studies contributed to the refinement of the traditional explanatory variables and to the addition of new ones, and the others improve the econometric specification of the model (nguyen, 2010). some criticism about the gravity model for its lack of theoretical foundations has emerged. indeed, the former theoretical foundation of the gravity model derivation centered on constant elasticity of dessalegn et al. determinants of export performance of spices 123 substitution preferences and goods that are differentiated by region of origin. subsequent extensions of it used the differentiated product framework with increasing return to scale, encompass factor endowments and taste variables that explain the microeconomic foundations for the gravity equation based on monopolistic competition or heckscherohlin structure that includes only the main variables such as gdps, population and distance. particularly, the gravity model can incorporate additional variables to control for the differences in factor endowments that could aid or impede exports between countries (alemayehu, 2009). 2.2. conceptual framework the measurement of the export performance has evolved significantly over time in two directions: multidimensional and one-dimensional measures. export performance can be labeled either as onedimension/single-proxy measures (that is covering one dimension with one proxy), as onedimension/multiple-proxy measures, or as multidimensional/multiple-proxy measures. the decision to use one-dimensional/ single-proxy measures results in testing every relationship hypothesized separately with each export performance measure in the design. it also explained the reason that one dimension of export performance relates in different manners to the determinants. and it should not be forced into a single composite measure for one dimension and must be tested separately(nguyen, 2010). accordingly, the study used an approach so-called as one dimension with one proxy which enables us to measure the coffee export sales (usd values) as a proxy for the ece performance. 2.3. data and sampling this study used annual panel data of ethiopia’s major spices export and its nine trade partners over the period of 2005–2015. the panel data has better efficiency than other data types and offers more variability, more degree of freedom and reduce the multicollinearity among explanatory variables, improve the reliability of the regression results(grote and winter, 2009). in this paper, panel data were used to investigate the determinants of ethiopia's spices export performance. the data were collected from the top nine ethiopia's spices trade partners or destinations namely; india, yemen, jordan, saudi arabia, united arab emirates, israel, united states, kenya and sudan. the selection of these countries was based on the availability of data and the distribution of spices exports by destination. among 38 spices importing partners, these top nine countries constituting about 85 percent of ethiopia's spices export value were sampled for this study. the annual values of major spices export to each of the nine importer countries were collected from ethiopian revenue and custom authority(erca), while the data on most of the independent variables such as annual gross domestic products of ethiopia and trade partners (gdpij), ethiopia's foreign direct investment (fdi), bilateral exchange rate (er), population size and internal transport infrastructure were obtained from the wdi (world development index), imf (international monetary fund)and unctadstat databases. moreover, data on the institutional quality index and the distance between ethiopia's capital (addis ababa) and capital cities of the trade partners in kilometers were accessed from www.indo's website and world bank's(wb) worldwide governance indicators respectively. 2.4. model specification and variables description the basic gravity model postulates trade between the two countries depends upon their gross domestic product (gdp), population size and distance between them. the underlying rationale of the model is that the volume of trade between the two countries depends on each country's trade potential and the trade attraction forces between them. the model is referred to as gravity simply to capture factors that would induce countries to trade with each other. however, because of the existence of a huge amount of variations in the trade that cannot be explained by the traditional variables, other explanatory variables have been included(grote and winter, 2009). in most studies, the gravity approach is denoted as a rather simple but robust approach to estimate bilateral trade flows due to its simple application to different aspects of the trade, it is very attractive for researchers. since the theoretical foundations of the gravity model are better understood and developed the application is also justified by the economic theory. the advantage of the gravity model was that, first, the panel can capture the relevant relationships among variables over time; and second, the panel can examine unobservable trading partners’ individual effect (roy and rayhan, 2012). they argue that panel data methods are the most proper for separating time-invariant and countryspecific effects. several empirical studies have employed the augmented gravity model to investigate the determinants of bilateral trade between different countries and found important results (yishak, 2009;alekaw, 2016; potelwa et al., 2017). therefore, in this paper, gravity models were adopted as an analytical tool to estimate the determinant of spices export performance between ethiopia and sampled trade partners. this model is tested using panel data representing internal supply capacity and foreign market access. thus, the value of spices (turmeric and korarima) exports from ethiopia to its major trading partners is defined as follows: 3 51 9 10 2 4 6 7 8 ij it i i i i ji 1 j ij ij exv (gdp ) (popit) (fdi ) (inf ) (fer ) (iq ) (gdp ) (popjt) [(ftp ) (wd ) ] u (1)          − =  dessalegn et al. east african journal of sciences volume 14 (2) 121-130 124 except for dummies (comes and border), all the variables were transformed to natural logarithms since the gravity equation has multiplicative features. the log transformation allows estimating a linear regression and interpreting the estimated parameters as the elasticity of the volume of trade. after making adjustments and modifications the model is constructed as follows: ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ( ) ij 1 i t 2 i t 3 it 4 it 5 it 6 ijt 7 jt 8 jt 9 jt 10 ijt 11 ij ijt ln exv = + ln gdp + ln(pop )+ ln fdi + ln inf + ln iq + ln rer + ln gdp + ln(pop ) + ln ftp + ln wdist + dm + e             (2) where; ijt exv is export value of spices in year t; ijt rer is the average bilateral exchange rate ; it gdp is the usd value of ethiopia's gross domestic product in year t; it p is ethiopia's' population in year t; jt gdp is the usd value of gross domestic product of country j; population of partner country j; itfdi is foreign direct investment in year t; itinf indicate the quality of ethiopia's internal transport infrastructure in year t; it iq is the institutional quality index of ethiopia; jt ftp is the foreign trade policy index of country j; ijt wdist is the weighted distance between ethiopia and trade partners; dmijis dummy variables and ijte is the stochastic term. panel data involves different models such as pooled ols, fixed effects and random effects that can be estimated. the main problem of the pooled ols model is that it does not allow for heterogeneity of countries. it does not estimate country-specific effects and assumes that all countries are homogenous (abu et al., 2010). the random-effects estimator is appropriate when the unobserved effect is thought to be uncorrelated with all the explanatory variables in which it can be left in the error term, and the resulting serial correlation over time can be handled by generalized least squares estimation. on the other hand, the fixed effects estimator is efficient when the idiosyncratic errors are serially uncorrelated and we make no assumptions about the correlation between the unobserved effect and the explanatory variables. the fixed-effects model is simply a linear regression model in which the intercept terms vary over the individual units which is constant in the case of the randomeffects model (wooldridge, 2012). hence, in order to test the null hypothesis that the repressors and individual effects are not correlated or not systematic, the hausman specification test was employed. the test distinguishes an efficient estimation model between random and fixed effects. if the null hypothesis of the hausman test is rejected the random effects is not appropriate, instead; the fixed effects model would be preferred and vice-versa. 2.5. definition of variables and hypothesis ethiopia' spices export performance which is captured by the annual usd values of spices exports to each of the trading partners countries are hypothesized to be affected by both supply-side and demand-side factors such as ethiopia’s gross domestic product (gdp), ethiopia's foreign direct investment (fdi), population of both exporters and importers, internal transport infrastructure, real bilateral exchange rate, foreign trade policy, importing country’s gross domestic product (gdp), the distance between ethiopia and her trading partners and institutional environment of ethiopia. exporting country’ (ethiopia's) gdp: gdp is considered as a proxy of economic mass, which is a basic variable of the gravity model. most empirical papers around the world support the idea that gdp has a positive impact on exports. in his paper, eita (2008) found out that an increase in namibia’s gdp caused exports to increase during the examination period of 1998 2006. in a more recent study, aslanov et al. (2010) also found out that an increase in gdp led to higher exports, and vice versa, of three countries in south caucacus, including azerbaijan, georgia and armenia. thus it is hypothesized that there is a positive relationship between the gdp of a country and its exports. ethiopia' foreign direct investment (fdi): there has never been a single conclusion about the effect of fdi on export from previous studies because they showed different results. gunawardana and sharma (2009) and pemasiri and sharma (2010) pointed out that inward fdi has a significant positive influence on australian manufacturing exports in the long-term. in this research, fdi represents a measure of product development in the export sector and it can be expected to contribute to the enhancing of a country’s competitiveness on international markets by increasing the technological content of exports. fdi is included in this study as stock since fdi stock measures its productive capacity. as it is believed that the transformation of the composition of exports increases with fdi, the sign of this variable is expected to be positive. real bilateral exchange rate: the exchange rate is a fundamental determinant of a country’s trade. therefore, there are numerous empirical studies being conducted on how this variable would affect a country’s exports. in fact, some studies show a positive impact of national currency depreciation on its export while others show no impact. there are various results from previous research papers. aljebrin (2012), dessalegn et al. determinants of export performance of spices 125 supported the idea that a fall in currency value makes costs of domestically produced goods lowered, which consequently enhances competitiveness in export in china and saudi arabia, respectively. therefore, it is hypothesized that while an appreciation of the real exchange rate affects spices exports negatively, depreciation affects exports positively. internal transport infrastructure: internal transport infrastructure is captured by the percentage of paved roads out of the total roads. a higher rating indicates a better infrastructure. better infrastructure should lead to higher trade and therefore more exports from ethiopia. thus, the coefficient of internal transport infrastructure is expected to be positive. fugazza (2004) found that the internal transport infrastructure has a significant and positive impact on raising exports. foreign trade policy (ftp): trade policy is a measure of the degree of tariff and non-tariff barriers that trading partners apply. trade policy in this study is peroxide by a trade policy index, which is taken from the index of economic freedom created by the heritage foundation. the index ranges from 0 to 100. a country with zero tariffs and non-tariff barriers will have a trade freedom score of 100. this is to means that a score of 100 signifies an environment that is most conducive to trade. therefore, given that more freedom encourages trade, the sign of the index variable is expected to be positive. importing country’s gdp: the import demand of foreign countries is determined by their income. the higher the income of the importing country is, the greater the demand for ethiopia’s exports. hence, the coefficients of ethiopia’s trading partner gdp are expected to have positive signs. in most researches applying the gravity model, the results revealed that an increase in the importing country’s gdp would lead to an increase in the export volume of the exporting country. according to a study conducted by yishak (2009 the importing country’s gdp has a positive relationship with exports. population (popit and popjt): the effect of exporter country population could be positive or negative depending on whether the absorption effect or economies of scale effect is dominant. a large population may indicate a big domestic market and large resource endowment, in which case a larger absorption effect may lead to less export. if this is the case, a negative sign will be expected. on the other hand, a large domestic market may imply the utilization of the economies of scales so that the expected sign of the population coefficient would be positive. for similar reasons, the coefficient of importing country population is indeterminate where the absorption effects and economies of scale effects are expected to affect their imports positively and negatively, respectively. the larger the market the more it trades, so the market size is expected to turn out with positive signs (ebaidalla and abdalla, 2016). distances: distance between an exporter and its importers are used as a proxy for transportation costs. this is the basic variable of the gravity model. it is normally stated that as countries stay far from each other, the transportation costs between them are higher. consequently, they tend to trade less. based on distance data and gdp, the weighted distance between ethiopia and its trading partners for each year in the observation period is calculated. hatab et al. (2010) found in their research that transportation costs, proxies by distance, influenced egyptian agricultural exports negatively, based on time-series data from 1994-2008. orindi (2011) also found out that exports reduced as the distance between them and their importers got larger in ethiopia and kenya, respectively. the coefficient of distance is expected to be negative, as the larger the physical distance between two countries’ economic centers, the higher is the cost of transporting goods. the high such cost, the lower trade should be. (beleska-spasova, 2014) institutional quality (iq): the institutional environment encompasses macroeconomic stability and openness to trade, as well as the enabling environment for markets consisting notably of the legal and judiciary system, the financial system, taxation, labour relations, investment procedures, and customs administration. the world bank's worldwide governance indicators (wgi) project (kaufmann et al., 2009) estimates the institutional quality of a particular country in terms of rule of law, government effectiveness, regulatory quality and control of corruption. the rank (out of 100) is given for each component. the aggregate value of the four components as a proxy for ethiopia’s institutional quality is taken. a higher aggregate value is associated with better institutional quality. hence, the sign of this variable is expected to be positive. the description, measurement and expected effects of each variable on the export potential of spices are summarized in table 1. dessalegn et al. east african journal of sciences volume 14 (2) 121-130 126 table 1. summary of variable description and hypothesized effects on spices export flows. variables and measurement measurement expected sign ethiopia's gdp continuous (measured in usd) positive ethiopia's gdp per capita continuous (measured in usd) positive foreign direct investment continuous (measured in usd) positive real exchange rate continuous (measured in km) negative internal infrastructure continuous (percentage of paved road) positive ethiopia's institutional quality continuous (index ranging 1-100) positive foreign trade policy continuous (index ranging; 0-100) positive trading partners'' gdp continuous (measured in usd) positive partners'' gdp per capita continuous (measured in usd) positive weighted distance continuous (measured in millions) negative ethiopian population continuous(measured in millions) positive partners' population continuous (measured in millions) positive comesa membership dummy (1, if belongs to membership) positive common border dummy (1, if they shared common border) positive 3. empirical results and discussion before the estimation of the model, an inspection has been performed for testing the normality of all the variables used in the estimation. for most of the variables, it was observed that the null hypothesis of a normally distributed random variable is rejected. thus, the natural log-transformed variables were used for analysis to remove normality problems. a diagnostic test was also been conducted in order to examine which estimation technique generated the data. accordingly, the hausman specification test was executed to identify the appropriate gravity model between fixed and random effects. the test result confirmed that the error terms are not correlated with country-specific circumstances as the probability of chisquare value (0.9387) is higher indicating there are no significant differences between fixed effect and random model coefficients. thus, the random effect model is appropriate and efficient for the estimation. table 2. summary of haussmann specification test for random or fixed effects. variables coefficients sqrt (diag (v_b-v_b)) s.e (b) fixed effect (b) random effects (b-b) difference lngdpeth -1.066895 -1.390727 0.3238317 0.3076521 gdpeth2 -0.0006 -0.0003 -0.0003 0.0002 lnfdieth 3.9032 4.9346 -1.0314 1.2917 lnfdiethsqr -0.3405 -0.4261 0.0856 0.1095 lnrerij -0.5871 -0.5396 -0.0474 0.4376 lpavdroad 0.1533 0.0894 0.0638 0.3900 lniqeth -1.3425 -1.4212 0.0787 0.3939 lnftppart -0.7971 -0.6670 -0.1301 0.8576 lngdppart 1.1556 0.2699 0.8858 2.0738 lngdppcpart -1.5148 1.2528 -2.7676 2.3313 popeth 0.2082 0.1521 0.0561 0.0364 poppart 0.0102 0.0041 0.0061 0.0075 chi2 (11) = (b-b)'[(v_b-v_b)^(-1)](b-b) = 4.07; prob>chi2 = 0.9387 source: model result, 2016. moreover, breusch and pagan test for heteroscedasticity were applied and the null hypothesis of homoscedasticity disturbances is rejected at a one percent significance level suggesting that the variance is not constant. thus, the robust command was applied to remove the problem of heteroscedasticity. the estimation results also indicate that the model has an overall r-square of 0.626, confirming that the variables included in the random-effects model explain 62.6% of the variations in spices trade flow. the wald statistic of 138.99 with a p-value of 0.0000 shows that the variables included in the random-effects model are jointly significant at less than one percent significance level as indicated in table 2. dessalegn et al. determinants of export performance of spices 127 table 3. random effects gls model estimation results for determinants of spices export. variables symbol coefficient robust std. err. z p>z ethiopia's annual gdp lngdpeth -1.3907 1.5922 0.8700 0.3820 ethiopia's gdp square gdpeth2 -0.0003 0.0007 0.4200 0.6740 foreign direct investment lnfdieth 4.9346* 2.9360 1.6800 0.0930 foreign direct investment sqre lnfdiethsqr -0.4261* 0.2505 1.7000 0.0890 bilateral real exchange rate lnrerij -0.5396*** 0.0639 8.4400 0.0000 percentage of paved road lpavdroad 0.0894 1.0545 0.0800 0.9320 ethiopia's institutional quality lniqeth -1.4212* 0.8115 1.7500 0.0800 foreign trade policy index; lnftppart -0.6670 0.5275 1.2600 0.2060 trading partners'' gdp lngdppart 0.2699*** 0.0863 3.1300 0.0020 partners'' gdp per capita lngdppcpart 1.2528*** 0.2531 4.9500 0.0000 weighted distance lndistij -2.1592*** 0.3025 7.1400 0.0000 ethiopian population popeth 0.1521* 0.0814 1.8700 0.0620 population of trade partner poppart 0.0041*** 0.0006 6.4500 0.0000 comesa membership comesa -5.8719*** 0.8743 6.7200 0.0000 sharing common border border 1.5129*** 0.5797 2.6100 0.0090 constant _cons 6.6398 10.5897 0.6300 0.5310 number of obs 99 wald chi2(15) = 138.99 number of groups 9 prob> chi2 = 0.0000 r-sq: within = 0.1278 0.1278 between = 0.9945 0.9945 corr (u_i, x) = 0 (assumed) overall = 0.6261 0.6261 note: ***, **and * indicate the significance of the coefficients at 1%, 5%, and 10% levels of significance, respectively source: authors computation from the survey (2016). among the determinants of spices trade performance, internal supply capacity; the log of foreign direct investment (fdi), ethiopia's population (popeth), the log of the real bilateral exchange rate (rer) and log of institutional quality were found to be statistically significant. the result showed that the log of foreign direct investment (fdi) significantly affected the performance of spices trade with an expected positive sign (addisu, 2014; alelign, adame 2014; alekaw, 2016) also found that fdi has a significant positive influence on australian manufacturing exports in the long-term. similarly, the study by waleed and shelaby (2011) on modeling and estimating the export potential of the egyptian spices subsector found a positive effect of fdi on trade performance. the result also indicated that ethiopia's population has a significant and positive influence at a 10 percent significance level. this may indicate a large domestic market may imply utilization of the economies of scales rather than the dominance of absorption effect. controlling for other things unchanged, it is confirmed that a percent growth in population of the trading partner would increase the exports of spices by 0.152 percent. the estimated coefficient also indicates that the real exchange rate is negative and statistically significant at less than one percent suggesting as the exchange rate appreciates spices export revenue declines thereby devaluation of domestic currency has a noticeable positive contribution to ethiopia's spices (turmeric and korarima) export. the real exchange rate of the exporting country affects the price of goods that are imposed to the importing country. if the real exchange rate of exporting countries increases or appreciates, the export price will increase and the importing country will pay higher to import the things from the exporting country. the estimated coefficient implies that a percent increase in the real exchange rate would lead to a decline in spices (turmeric and korarima) export value by 0.540 percent, assuming other variables kept unchanged. similar results were obtained by other researchers regarding the effect of the bilateral exchange rate on export values (aljebrin, 2012; inayah et al., 2016). the result was also consistent with the (negussie and dessalegn, 2014) that investigated determinants of bilateral trade between ethiopia and its major trading partners’ and they found that bilateral real exchange rate had a negative impact on ethiopia’s total export performance. the model output also depicts that the institutional quality (iq) has a significant negative effect on spices export value contrary to the hypothesis. the negative sign might be due lack of modern marketing institutions that properly guide the production and regulate the marketing of spices as this commodity is not in the system of ethiopian commodity exchange (ecx), unlike other agricultural export. it implies that poor institutional quality (poor market regulatory system) will discourage spices export flows by 1.421 percent. ebaidalla and abdallat(2016) found that inefficient institutions resulted in low investment and productivity thereby leads to low export flows. except for foreign trade policy, all external demand side determents of export performances were found to dessalegn et al. east african journal of sciences volume 14 (2) 121-13 128 be significant. the trade partners' log of gdp used as a proxy for importers demand/market size was the statistically significant and negative influence on spices trade performance. the result suggests that a higher importers' gdp means a higher absorption capacity, implying the partner country is able to import more spices. hence, a percent increase in importer's log of gdp will increase spices export value by 0.272 percent. this is line with the theory behind the conventional gravity model that states the size of the economies enhances the amount of trade between trading partners. ethiopia's major spices (turmeric and korarima) export performance was significantly and positively affected by importers; log of gdp per capita, too. the estimated positive coefficient implies that the levels of income determine the purchasing power of consumers at export destinations; the higher the income of consumers the more products they could purchase and hence rising spices export performances. the positive value is consistent with the theoretical expectation of gravity trade that expects that trade capacity increase with an increase in a partner’s economic size. so, holding other things unchanged, it is evident that a percent improvement in log per capita gdp of the partners will increase their demand for spices export by 0.270 percent. this result is consistent with the demand theory and other empirical studies on trade (inayah et al., 2016; baker and yuya, 2020). this finding also corroborates the findings of karamuriro and karukuza (2015) who use the gravity model, discovered that the real gdp of importing countries had a positive effect on the value of bilateral trade between considered in the study for the years 1980–2012. moreover, a variable population proxy for importers market sizes was statistically significant and positive as a hypothesis. it means that a percent growth in importer’s population would lead to a 0.004 percent improvement in the spices export earnings, assuming that other things remain the same. some of the past studies agreed on the positive relationship between export flows and the total population of importing countries (elshehawy et al., 2014). the weighted distance (wdist) between ethiopia and trade partners has affected the performance of spices trade flows significantly and negatively. the results provide strong support for the hypothesis that transportation costs are an important foreign market access determinant affecting spices trade performance .i.e. distance is a proxy for various factors such as transportation costs, delay during shipment, synchronization costs, communication costs, and transaction costs that could influence trade flows (alemayehu, 2009). from the estimated results, it is evident that a percent difference in distance will reduce spices export value by 2.159 percent in line with the economic theory of gravity model. this result is also consistent with the following empirical studies on export determinants (yishak, 2009; alelign, 2014; inayah et al., 2016). the dependence of spices exports on transport costs implies that besides emphasizing large economies in the world as the major destination markets, the government needs also to pay adequate attention to destination markets with cheaper transport costs. access to such markets should be facilitated by relevant policies to take advantage of the geographical location in strengthening spices exports’ competitiveness. contrary to the hypothesized effect and the existing empirical evidence, the variable comesa membership has found statistically significant and negatively affecting spices export value. the negative coefficient of this variable may suggest that ethiopia exports below what other countries export to comesa, might be due to lack of large-scale private sector participation in production to benefit from economies of scale. equivalently, this to mean that with continued such trade underperformance, being ethiopia a membership of comesa would reduce spice export value by 5.872 percent. the other possible justification for the unexpected negative sign might be associated with the fact that; as the majority of trade partners are also spices exporters they may appear to be competitors with ethiopia's spices (for instances, india and china are the large producers and exporters of turmeric) thus adversely affecting the performance of spices export. this result is consistent with a study conducted by alkekaw (2016) on the determinants of foreign trade in ethiopia. the common border variable is significant and has a positive sign suggesting that there have been more spices trade with the neighboring countries than relatively distant countries. the positive coefficient on “common border” indicates that the immediate proximity of the two countries increases their tendency to trade. as most of ethiopia's spices, export destinations are neighboring countries spices trade could easily flow due to the country's urgent need for foreign currencies. thus, being a trade partner share a common border will increase the spices export value by 1.513 percent. the empirical analysis of pakistan’s trade conducted by khan et al. (2013) indicate similar positive results regarding the relationship between export and shared border. 4. conclusions the results have demonstrated that there is a significant and positive relationship between direct investments (fdi) and spices export performance. this variable contributes to the improvement of the country's export in general and spices export in particular. thus, the government and other relevant stakeholders should continue to exert its efforts to attract foreign investment by taking various measures. the results also indicated that there was a strong negative and significant relationship between the exchange rate and dessalegn et al. determinants of export performance of spices 129 spices export value. in line with this, the government has to ensure a stable exchange rate policy in order to avoid the exchange rate risk attached to the import prices and profit considerations of direct investors that could contribute to export growth by investing in the spices subsector. it can also be suggested that depreciation of the real exchange rate would cause again in the competitiveness of the country thereby encouraging the spices export flows. both gdp and gdp per capita of importing countries were confirmed to have a significant and positive relationship with spics export value of ethiopia. it implied that an improvement in these macroeconomic variables in each destination country would create demand for ethiopia's spices. therefore, the country should target spices export to partners with larger economies. the population of importing countries is another significant variable affecting the spices exports. thus, there is a foreign market demand for spices that the country could be benefited from. moreover, the policymaker should design policies that promote economic growth. distance is also an important variable influencing spices trade flows between ethiopia and each destination country (alemayehu, 2009). since the distance between countries is associated with transportation costs a more distant would worsen spices export flows. the dependence of spices exports on transport costs implies that besides emphasizing large economies in the world as the major destination markets, the government has to pay adequate attention to the destinations that relatively reducing transport costs. membership of comesa was negatively related to spices export value which might depict the country doesn't benefit from spices export to these common markets. the strong and negative relationship between this common market and spices trade performance may also suggest ethiopia exports below what other countries export. the current and future spices demand and supply prospects need to be assessed in such regional market. addressing supply constraints and the competitiveness of comesa exports is important. furthermore, sharing a common border with a partner affected the spices export performance significantly with its expected positive sign. in order to expand bilateral trade flows, it is appeared to be more desirable for ethiopia to promote exports to countries in close proximity. some future research can also be suggested in order to broaden the existing pool of knowledge on the subject: first due to lack of data on spices products in the form of oleoresin &essential oils and powdered mixes were not included in estimating the spices export value in this study. secondly, the study is confined to evaluate factors influencing the export performance of the two spices within the on-going value chain research. therefore, there is a scope for further studies to consider all types of spices and their emerging valueadded products (essential oil and spices mixes) in analyzing the spices export performances and its determinants in ethiopia. 5. acknowledgments i would like to express my special gratitude and appreciation to wolkite university and the global research capacity building program of global development network for financing the field research. in this aspect, my profound sense of gratitude goes to the bercea program designers and coordinators prof. mengistu ketema and dr. degye goshu. 6. references addisu, a. 2014. spice sector development in ethiopia: scenario and competitiveness. in: report of the third spices, aromatic and herbal plants subsector stakeholders platform workshop. addis ababa, ethiopia. alekaw, k. 2016. determinants and potentials of foreign trade in ethiopia: a gravity model analysis, munich personal research archive paper. alelign, a. 2014. ethiopia’s export performance with major trade partners: a gravity model approach. journal of natural sciences research, 4(20): 21–28. alemayehu, g. 2009. fundamentals of international economics for developing countries: a focus on africa, volume 1: trade theory and policy, africa economic research consortium, nairobi, kenya. baker, m.m. and yuya, b.a. 2020. the determinant of sesame export performance in ethiopia: a panel gravity model application. turkish journal of agriculture, food science and technology, 8(3): 714– 720. beleska-spasova, e. 2014. determinants and measures of export performance comprehensive literature review. journal of contemporary economic and business issues, 1(1): 63–74. deresa, t. 2009. practices and constraints of turmeric production and marketing by smallholder farmers: the case of yeki woreda, sheka zone in southwestern ethiopia. msc thesis, addis ababa university, ethiopia. ebaidalla, m.e. and abdalla, a.a. 2016. performance of sudanese agricultural exports: a gravity model analysis. a paper prepared for the conference on structural reform, transformation and sustainable development in post-secession: economic, political and social perspectives. the university of khartoum, sudan. elshehawy, m.a., shen, h. and ahmed, r.a. 2014. the factors affecting egypt’s exports: evidence from the gravity model analysis. open journal of social sciences, 2: 138–148. eyayu, t. 2017. determinants of agricultural export in sub-saharan africa: evidence from panel study. dessalegn et al. east african journal of sciences volume 14 (2) 121-13 130 american journal of trade and policy, 1(2): 62–70. fugazza, m. 2004. export performance and its determinants: supply and demand constraints. unctad policy issues in international trade and commodities no. 26. girma, h. and solomon, a. 2012. success and challenges of the informal seed system of spices, aromatic and medicinal plants in ethiopia: conference paper, institute of ethiopian agricultural research, addis ababa, ethiopia. grote, u. and winter, e. 2009. value chain analysis methodologies in the context of environment and trade research. discussion paper no. 429. herms, s. 2015. business opportunity report spices in the series written for the ethiopian-netherlands business events. rijswijk, the netherlands. inayah, i., oktaviani, r. and daryanto, h.k. 2016. the analysis of export determinant of indonesian pepper in the international market. international journal of science and research, 5(11): 1856–1860. itc (international trade center). 2015. all acp agricultural commodities programme, spice subsector strategy for ethiopia. addis ababa, ethiopia. karamuriro, h.t. and karukuza, w.n. 2015. determinants of uganda’s export performance: a gravity model analysis. international journal of business and economics research, 4(2): 45–54. khan, s. and ihtisham. d.k. 2013. an empirical analysis of pakistan’s bilateral trade: a gravity model approach. the romanian economic journal, xvi(48): 103–120. mofed (minstry of finance and economic development). 2010. ethiopia’s growth and transformation plan: federal democratic republic of ethiopia. addis ababa, ethiopia. mofed (ministry of finance and economic development). 2016. growth and transformation plan: federal democratic republic of ethiopia. addis ababa, ethiopia. moti, j. 2007. econometric analyses of horticultural production and marketing in central and eastern ethiopia. phd thesis, wageningen university, the netherlands. negussie, z. and dessalegn, g. 2014. determinants of bilateral trade between ethiopia and its major trading partners’: a gravity model approach. journal of economics and sustainable development, 5(15): 82–89. nguyen, b.x. 2010. the determinants of vietnamese export flows: static and dynamic panel gravity approaches. international journal of economics and finance, 2(4): 122–129. orindi m.n. 2011. determinants of kenyan exports: a gravity model approach. international journal of economic and political integration. 1(1):3–14. potelwa, x.y., lubinga, m.h. and ntshangase, t. 2017. factors influencing the growth of south africa’s agricultural exports to world markets. european scientific journal, 12(34): 195–204. waleed y.s. and ayman a.s. 2011. value chain analysis for the egyptian herbs & spices sub-sector: modeling and estimating export potential. journal of american science, 7(12): 565–578. wooldridge, j.m. 2012. introductory econometrics: a modern approach. 5th edition. cengage learning, usa. yishak, t. 2009. determinants of ethiopia’s export performance: a gravity model analysis. trade and development discussion paper, no. 1, bkp, development research and consulting, germany. microsoft word paper-5(proof revised) final.docx ©haramaya university, 2020 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2020) volume 14 (1) 51-64 licensed under a creative commons *corresponding author: e-mail: weldum21@gmail.com attribution-non-commercial 4.0 international license. standard heterosis for grain yield and yield related traits in maize (zea mays l.) inbred lines in haramaya district, eastern ethiopia woldu mogesse 1*, habtamu zelleke 1, and mandefro nigussie 2 1 school of plant sciences, haramaya university, p. o. box 138, dire dawa, ethiopia. 2 ethiopian institute of agricultural research (eiar), addis ababa, ethiopia. abstract: determination of heterosis in maize hybrids is necessary for identification of superior f1 hybrids for breeding programs. therefore, this study was conducted to estimate the amount of standard heterosis for grain yield and related traits in order to identify potential hybrid for future breeding schemes. eight maize inbred lines were mated through a half diallel mating design (griffing’s method iv, model i). the resulting twenty-eight f1 hybrids along with two standard checks (bhqpy 545 and mh 138) were evaluated using alpha-lattice design with three replications during 2017/18 main cropping season at haramaya university research site (raare). analysis of variance revealed significant variations for all traits indicating the existence of genetic variability. the result of heterosis estimation showed considerable amount of positive and negative heterosis for all traits studied. the highest percentage of standard heterosis for grain yield was manifested by the cross combinations l3 × l6 over bhqpy 545, and l3 × l6, l3 × l8, l2 × l5, l6 × l8, l1 × l4, l4 × l6 and l3×l4 over mh138 (greater than 20% yield advantage). the maximum positive and significant standard heterosis was recorded for l3 × l6, and l1 × l4 for 1000 kernel weight and number of kernels per row, respectively over the two checks bhqpy-545 and mh-138. the observed highest heterosis for grain yield and related traits indicated the possibility of increasing yield by exploiting heterotic potential of maize genotypes. the information generated by this study could be useful for researchers who need to develop high yielding maize hybrids. hence the potential hybrids could be recommended for commercial use, after verifying the results by repeating the research over years and across locations. keywords: crosses; f1 hybrids; maturity; standard checks. 1. introduction maize (zea mays l.; 2n =20) is an important cereal crop to enhance food security and the demand for its grain is increasing every year (abate et al., 2015), this is due to diverse uses, wide adaptability, and high yielding potential and genetic diversity. considering the paramount importance of maize as a staple in the diets of many developing countries, particularly in ethiopia the study intends to identify better performing crosses for the development of high yielding variety in eastern ethiopia, to assure food security for maize producers and consumers while enhancing the sustainability of maize production. the exploitation of hybrid vigor can be instrumental in increasing seed yield (nasim et al., 2014) to come up with more advanced varieties than the existing ones in many aspects. in maize, several methods have been employed for the prediction of hybrid performance considering the cost and time which is required for field evaluation of hybrids. selection of parents is the most important stage in any breeding programe to develop new genotypes having desirable characters. one of the methods to achieve this purpose is heterosis (ilker et al., 2010); khan et al., 2010; siddiqi et al., 2012) since breeding strategies based on selection of hybrids require expected level of heterosis. heterosis is important in breeding program especially for cross pollinated crop and is a great achievement to meet the world’s food needs (duvick, 1999). however, the definition of heterosis differs depending on the basis of comparison used. heterosis is the enhancement in size, growth, fertility and yield in progeny compared with their inbred parents (thiemann et al., 2014; jiban et al., 2018). the biological phenomenon of heterosis is described by the trait-specific performance of highly heterozygous f1 hybrids with respect to the average (mid-parent) or high parent performance of their genetically distinct homozygous parents in measurable characters (paschold et al., 2010). similarly, heterosis is a phenomenon in which an f1 hybrid of two genetically dissimilar parents shows superiority over the standard or commercial variety, which is often included in the trial as a check variety. it is also called economic heterosis or superiority over check variety. therefore, a new maize hybrid must be superior to an existing woldu et al. east african journal of sciences volume 14 (1) 51-64 52 commercial hybrid variety (i.e. check variety) for grain yield and other economic traits to be released as a commercial variety. thus, determination of heterosis in reference to a standard check (standard heterosis) is required for commercialization of maize hybrids. so far, standard heterosis in maize has been extensively studied for different sets of new inbred lines developed/introduced and adapted at different times (shushay, 2014; reddy et al., 2015; ziggiju et al., 2016; natol et al., 2017; huiyong et al., 2018; abiy et al., 2019). the magnitude of heterosis provides information on extent of genetic diversity of parents in developing superior f1s so as to exploit hybrid vigour and has direct bearing on the breeding methodology to be adapted for varietal improvement and their commercial utilization (rajesh et al., 2014). the square of gene frequency difference between parental lines, pattern of distribution of dominance (ambi-directional or unidirectional) and genes are in dispersive or associated are also determinants of heterosis. according to hallauer & miranda (1988) the manifestation of heterosis depends on the genetic divergence of two parental varieties, also genetic divergence of the parents is inferred from the heterotic patterns manifested in a series of cross combination. riday et al. (2003) suggested that in many cases heterosis can be accounted for by the interaction of genes controlling morphologically divergent traits between the parents. hybrid breeders have always been interested in the selection of potential lines among the available parental lines which are expected to give heterotic hybrids to develop higher yielding, better performing hybrids. therefore, the objective of the present study was to estimate the amount of standard heterosis in maize hybrids for grain yield and yield related traits in order to identify potential hybrid for future breeding schemes. 2. materials and methods 2.1. description of study area the study was conducted at haramaya university main campus (raare research site) in 2017/18 cropping season. the study area is located at an altitude of 2020 meters above sea level and lies at 9° 26' n latitude and 42°3' e longitude. the area received an average annual rainfall of 727 mm during the 2018 main cropping season. the minimum and maximum mean annual temperatures during the cropping season were 8.99 oc and 25.15 oc, respectively (haramaya university weather station, 2018). 2.2. experimental materials the planting materials were comprised of eight maize inbred lines which were crossed in 8×8 half diallel mating design (griffing’s method iv, model i) in 2017 at haramaya university crop research site (raare) to produce twenty-eight f1 hybrids. bhqpy-545 are medium maturing single cross hybrids released by bako national maize research project (bnmrp) for mid to high potential maize growing agro-ecologies of ethiopia, while mh 138 is drought tolerant hybrid released by melkassa agricultural research center, ethiopia and was used as a standard check. the resulting 28 f1 hybrids and two standard checks (bhqpy 545 and mh 138) were tested in the 2017/2018 cropping season at haramaya university crop research site (raare). the lines were obtained from haramaya university maize research program. list and pedigrees of the inbred lines used in the dialle crosses are depicted in table 1. table 1. inbred lines used in the diallel cross. code inbred lines pedigree l1 [pool9ac7-sr(bc2)]fs211-1sr-1-1-1-#/cml144(bc2)-14-8-4-2-2-1-#-1-b-2 l2 [kit/snsyn[n3/tux]]c1f1-##(gls=2.5)-32-1-1-#/cml176bc1f1-12-1-3-4-2-#-2-b-1 l3 [pool9ac7-sr(bc2)]fs211-1sr-1-1-1-#/cml144(bc2)-14-8-4-3-3-4-#-1-b-4 l4 [pool9ac7-sr(bc2)]fs48-1-1-1-1-1-#/cml144(bc2)-6-22-1-1-1-4-#-3-b-1 l5 [pool9ac7-sr(bc2)]fs211-1sr-1-1-1-#/cml144(bc2)-14-8-4-3-2-2-#-1-b-1 l6 [pool9ac7-sr(bc2)]fs211-1sr-1-1-1-#/cml144(bc2)-14-21-1-3-2-2-#-2-b-4 l7 [pool9ac7-sr(bc2)]fs59-2-2-1-1-#/cml144(bc1)f1-3-2-1-2-1-#-1-b-2 l8 [kit/snsyn[n3/tux]]c1f1-##(gls=2.5)-17-1-1-#/cml144(bc1)f1-5-1-2-1-1-#-2-b-1 2.3. treatments and experimental design the twenty-eight f1 progenies derived from the diallel crosses and the two commercial hybrid checks were planted using alpha-lattice designs with three replications. in all cases, two rows per plots were used, where the length of each row was 5.1 m with the spacing of 0.75 m between rows and 0.30 m within rows. an alley of 1.5 m left between the blocks. 2.4. procedure and field management two seeds were sown per hill to ensure enough stand, and then thinned to one plant per hill after two weeks of emergence (when seedlings were at a 3-4-leaf stage) to attain a population density of 44,444 plants per hectare. urea and nps fertilizers were applied at the rates of 140 kg/ha and 118 kg/ha, respectively. urea was applied in 2 equal splits. the first half application woldu et al. standard maize heterosis 53 was done at sowing along with nps fertilizer and the second was applied at the knee-high growth stage of the crop. moreover, all other necessary field management practices were carried out as per the recommendations for the study area and the crop. 2.5. data collection data on grain yield and yield related traits were collected on plot and individual plant bases. characters were recorded on plant basis by taking five random plants. the average was taken as the mean of the treatment. 2.5.1. data collected on plot basis days to anthesis (da): this refers to the number of days taken from planting up to the date when 50% of the plants started pollen shedding. days to silking (ds): this is the number of days taken from planting to the date when 50% of the plants produced about 2-3cm long silk. anthesis-silking interval (asi): was calculated as the difference between number of days to anthesis and number of days to silking (asi = da – ds). days to physiological maturity (dm): was recorded as the number of days after sowing to when 50% of the plants in the plot formed a black layer at the point of attachment of the kernel with the cob. thousand kernel weight (tkw): after shelling, random kernels from the a bulk of the shelled grain in each experimental unit were taken and thousand kernels was counted using an electronic seed counter and weighted in grams and then adjusted to 12.5% grain moisture content. grain moisture: moisture content (%) in the grain was measured at harvesting by taking a sample of ears and shelling separately for each plot using a portable digital moisture tester. grain yield/plot (gy): grain yield per plot adjusted to 12.5% of moisture content was recorded for each plot in kg/plot using the formula below. adjusted grain yield (kg per plot = field of weight (kg per plot)x (100 − mc)x shelling (%) 100 − 12.5) x area harvested (plot size) where, mc = moisture content of grain at harvest. shelling percentage = x 100 shelling percentages for normal ears usually average about 80% (80/100 = 0.8). grain yield/ha (gy): was obtained by converting the grain yield obtained per plot into a hectare basis. harvest index (hi): was calculated by dividing grain yield (kg ha-1) by aboveground biomass yield (kg ha-1) and expressed in percentage donald (1962). 2.5.2. data collected on plant basis ear height (eh): was measured from the ground level to the uppermost useful earbearing node of five randomly taken plants. plant height (ph): was measured from the soil surface to the tassel starts branching of five randomly taken plants. ear length (el): was measured in centimeters from the base to the tip of ear. ear diameter (ed): was measured at the midsection along the ear length, as the average diameter of five randomly taken ears using a caliper. number of kernel rows per ear (nkre): was recorded as the average number of kernels row per ear from five randomly taken ears. number of kernels per row (nkr): was counted and the average was recorded from five randomly taken ears. 2.6. data analyses 2.6.1 analysis of variance the data were subjected to simple analysis of variance (anova) to see the existence of genetic variability whether there are differences between the tested genotypes using proc glm procedure of sas, version 9.0 sas (2002) before estimating standard heterosis. 2.6.2. estimation of standard heterosis economic/ standard heterosis of the f1 hybrids was estimated in percentage in relation to standard checks for traits that showed significant differences among crosses following the method suggested by falconer and mackay (1996): sh (%) = ×100 where, sh = standard heterosis, sv = standard variety (for each check), f1 = mean performance of f1. the differences in the magnitude of heterosis were tested following the procedure of panse sukhatme (1961). standard error and critical difference were also computed as: woldu et al. east african journal of sciences volume 14 (1) 51-64 54 se (d) = √ cd = se (d) × t where, se (d) is standard error of the difference, mse = error mean square from analysis of variance, r = the number of replications, cd = critical difference and t = value of t at error degree of freedom. the test of significance of heterosis in relation to standard check was done by ‘t’ test as suggested by snedecor and cochran (1967) as follows: heterosis ‘t’ = mean of f1 − standard check 2mse r the computed t-value was compared with the t-value at error degree of freedom corresponding to 5 or 1% level of significance. 3. results and discussion 3.1. analysis of variance (anova) the analysis of variance (anova) revealed that the twenty-eight f1 hybrids and the two standard checks showed significant differences for yield and yield related traits as well as disease reaction (table 2). genotypes significantly (p<0.01) differed for grain yield and yield related traits, namely, grain yield, biomass yield, days to anthesis, days to silking, plant and ear height, ear rot, plant aspect, ear aspect, common rust (puccinia sorghi), days to maturity, thousand kernel weight, kernels per row, and turccicum leaf blight (tlb). the existence of significant differences indicates the presence of inherent (genetic) variation among the materials evaluated, which makes selection possible for further breeding program (dan et al., 2018). in addition, ear length, ear diameter, kernel rows per ear, anthesis silking interval and harvest index showed significant (p<0.05) differences (table-2). the results also highlight the presence of sufficient genetic variability among the genotypes. the presence of variability among the genotypes for character of interest enables the breeder to conduct appropriate selection of the most desirable cross combinations. these results are in line with the results reported by bullo and dagne (2016) and matin et al. (2017). woldu et al. standard maize heterosis 55 table 2. analysis of variance due to mean square of genotypes for grain yield and related traits evaluated at haramaya, eastern ethiopia, during the 2017/18 main cropping season. source of variation df mean squares a gy (t/ha) dt (day) ds (day) asi (day) ps (scale) et (scale) pa (scale) ph (cm) eh (cm) ea (scale) rep 2 5.03 3.34 4.57 0.28* 0.09 0.03 0.03 112.83 198.28 0.01 blk/(rep) 10 1.26 0.87 1.69 0.05 0.04 0.04 0.08 141.15 37.1 0.05 genotypes 29 6.80** 9.55** 8.40** 0.15* 0.11** 0.13** 0.17** 1212.08** 401.90** 0.73** error 48 1.75 1.08 1.19 0.08 0.03 0.06 0.05 192.26 65.18 0.08 table 2. continued source of variation df mean squares a epp (#) dm (day) el (cm) ed (cm) nkr (#) nkre (#) tkw (g) by (t/ha) er (#) hi (%) rep 2 0.02 1.42 1.41 0.09 3.83 2.44 1277.02 39.63 1.28** 25.54 blk(rep) 10 0.01 0.77 5.66 0.19 3.54 4.03 3644.99 7.45 0.19 14.62 genotypes 29 0.18** 97.97** 9.38* 0.77* 30.04** 8.33* 10491.39** 48.58** 0.53** 39.56* error 48 0.02 0.69 5.29 0.45 4.17 4.63 4056.71 17.09 0.23 20.93 note: a gy = grain yield; bm = biomass yield; da = days to anthesis; ed = ear diameter; eh = ear height; el = ear length; epp = number of ear per plant; nkr = number of kernels per row; ph = plant height; nkre = number of kernel rows per ear; ds = number of days to silking; tkw = thousand kernels weight; dm = days to maturity; pa = plant aspect; ea = ear aspect; hc = husk cover; asi = anthesis silking interval; hi = harvest index; er = ear rot; et = turccicum leaf blight and ps = puccinia sorghi (rust).** = significant at p<0.01 level of probability and * = significant at p<0.05 level of probability woldu et al. east african journal of sciences volume 14 (1) 51-64 56 3.2. mean performance of genotypes the mean performances of the crosses are presented in table 3. among the crosses, the best yield was obtained from the cross l3×l6 while the least was l1×l5. the top four high yielding hybrids are obtained from the crosses l3×l6, l3×l8, l2×l5, and l6×l8 which exhibited higher mean value of grain yield relative to one of the best checks bhqpy-545. in addition, the mean value of the twenty crosses showed higher grain yields than the total average grain yield and out-yielded the grand mean of the second checkmh138. higher mean performances of these crosses over the standard checks indicate the possibility of obtaining a better commercial variety to enhance grain yield in maize. these results agree with the findings of shushay (2014) and girma et al. (2015) who reported significant mean performance of grain yield and related traits over the best hybrid check (bhqpy-545) in the study of combining ability of maize inbred lines for grain yield and yield related traits. berhanu (2009) also reported greater range in grain yield among test crosses of maize inbred lines evaluated at bako, hawassa and jimma research centers. the highest mean value of thousand kernel weight was obtained from the cross l3×l6 while the lowest in l1×l5 with the average value of 360.4 g. similarly, the highest mean value of harvest index retained from l2×l8 while the lowest for l3×l4 with the mean value of 40.44. among all, the crosses l6×l8 and l3×l5 are late mature hybrids whereas l4×l6 are early mature hybrid which are desirable for the development of early maturing varieties for moisture stress environments since earliness are desirable to increase water use efficiency. the highest mean value of number of kernel per row was obtained from l1×l4, while the least number of kernels per row was for l6×l8. higher number of kernel row per ear was recorded from standard check bhqpy 545, while the lowest number of kernel row per ear recorded from the cross l3×l4. the higher number of kernel per row and kernel row per ear are desirable to enhance grain yield of maize as the two traits are directly correlated with grain yield. the highest number of ear per plant was recorded from l3×l6; and the lowest was from l4×l5. this indicated that l3×l6 was prolific as compared to the standard check bhqpy-545, thus which will be used for the next breeding activity to enhance grain yield. among all the genotypes tested, l3×l8 attained the maximum ear length while l3×l7 was genotypes with shortest ear length. similarly, higher ear diameter was obtained from the check (bhqpy 545) while the lowest retained from l3×l4. maize genotypes with longer ear length and wide ear diameter may have inherent genetic potential to enhance grain yield. the cross l6×l8 that were late in anthesis and silking could be used as sources of genes for development of late maturing hybrids. conversely, the crosses l4×l6 which had shorter days to flowering could be regarded as early maturing types. early maturing types of crosses are appropriate in area with short rainy season so as to escape moisture stress encountering during grain filling stage or late in the season. anthesis-silking interval (asi) is the most important trait in determining drought tolerance. moreover, the crosses which exhibited low anthesis-silking interval (l1×l2, l1×l3, l1×l5, l1×l6, l1×l7, l1×l8, l2×l3, l2×l4, l2×l5, l2×l6, l3×4, l3×l5) indicates that the cross had short gaps between days to anthesis and silking, which are desirable characters for good seed setting and drought tolerance. on the other hand, if the gap between days to anthesis and silking is large, the viability of pollen would be reduced and abnormal fertilization might take place or fertilization may not happen consequently, which leads to yield lose. the result was in line with the report of bolafios and edmeades (1996). woldu et al. standard maize heterosis 57 table 3. mean performance of maize genotypes for grain yield and yield related traits at haramaya, eastern ethiopia, during the 2017/18 main cropping season. crosses traits considered a gy (t/ha) hi (%) dt (day) ds (day) asi (day) nkr (#) nkre (#) tkw (g) l1×l2 5.91 44.14 79.00 82.00 3.00 40.87 11.89 309.70 l1×l3 6.29 39.54 80.00 83.00 3.00 37.00 11.61 330.32 l1×l4 9.18 44.48 77.33 80.67 3.33 44.07 14.98 448.42 l1×l5 3.97 36.60 82.33 85.33 3.00 36.00 12.41 226.00 l1×l6 8.74 45.08 77.67 80.67 3.00 41.20 14.13 326.50 l1×l7 7.75 36.84 78.00 81.00 3.00 41.47 11.36 306.53 l1×l8 7.24 46.63 79.33 82.33 3.00 42.53 16.23 321.48 l2×l3 8.47 45.07 82.00 85.00 3.00 38.73 12.90 384.20 l2×l4 7.97 41.20 78.67 81.67 3.00 41.13 14.29 346.77 l2×l5 9.33 41.22 80.00 83.00 3.00 37.67 13.39 417.22 l2×l6 7.29 40.18 80.33 83.33 3.00 40.87 12.94 380.29 l2×l7 8.07 45.22 78.33 81.33 3.00 41.07 13.09 332.90 l2×l8 8.02 47.26 80.00 83.67 3.67 41.27 14.69 382.11 l3×l4 9.12 33.84 77.67 80.67 3.00 41.27 9.59 421.20 l3×l5 7.95 44.07 78.00 81.00 3.00 41.73 13.17 365.97 l3×l6 11.19 40.35 77.00 80.67 3.67 39.93 11.20 472.42 l3×l7 6.60 38.61 81.00 84.00 3.00 40.13 11.05 293.85 l3×l8 9.99 39.18 78.00 81.00 3.00 42.13 16.02 393.84 l4×l5 4.86 39.73 82.33 85.33 3.00 34.53 13.84 234.84 l4×l6 9.15 39.24 76.33 79.67 3.33 37.53 12.34 359.37 l4×l7 7.80 37.51 78.67 81.67 3.00 42.20 11.70 325.38 l4×l8 6.08 38.72 78.33 81.33 3.00 41.50 11.85 284.59 l5×l6 7.69 37.14 77.67 80.67 3.00 42.47 11.15 400.91 l5×l7 7.41 35.82 79.67 82.67 3.00 43.20 13.03 381.44 l5×l8 8.80 37.26 77.33 80.67 3.33 38.93 12.39 451.34 l6×l7 8.95 37.37 78.33 81.33 3.00 38.40 13.14 370.82 l6×l8 9.31 35.60 83.33 86.67 3.33 28.47 12.32 403.03 l7×l8 8.75 38.51 80.33 83.33 3.00 38.53 11.27 319.92 bhqpy 9.28 46.19 78.67 83.00 3.67 37.70 17.04 375.67 mh138 7.50 40.53 78.00 81.00 3.00 37.67 13.42 305.20 cv 16.60 11.31 1.26 1.25 9.02 5.16 16.62 17.67 lsd 2.17 7.51 1.64 1.69 0.46 3.35 3.53 104.00 max. 11.19 47.26 83.33 86.67 3.67 44.07 17.04 472.42 mean 7.96 40.44 79.12 82.26 3.11 39.67 12.95 360.40 min. 3.97 33.84 76.33 79.67 3.00 28.47 9.59 226.00 woldu et al. east african journal of sciences volume 14 (1) 51-64 58 table 3. continued crosses traits considered a ps (scale) et (scale) el (cm) ph (cm) eh (cm) ed (cm) er (#) dm (day) epp (#) l1×l2 1.50 2.00 17.32 198.33 93.33 4.24 1.74 161.67 1.03 l1×l3 1.50 1.83 14.65 170.00 70.00 3.98 1.43 160.33 1.02 l1×l4 1.00 1.33 19.50 211.67 101.67 4.86 1.10 167.67 1.53 l1×l5 1.50 1.50 15.26 185.00 83.33 3.88 1.56 161.00 1.10 l1×l6 1.33 1.50 17.69 203.33 90.00 4.31 1.00 168.33 1.50 l1×l7 1.50 1.50 15.30 198.33 93.33 3.97 1.17 156.00 1.03 l1×l8 1.50 1.50 19.03 196.67 96.67 5.20 1.56 160.00 1.05 l2×l3 1.50 1.50 19.21 180.00 83.33 4.59 1.00 165.33 1.28 l2×l4 1.67 1.67 16.55 200.00 90.00 4.64 2.18 163.00 1.16 l2×l5 1.33 1.33 19.94 211.67 105.00 4.83 1.39 168.00 1.15 l2×l6 1.67 1.67 18.10 195.00 96.67 3.77 1.95 160.33 1.05 l2×l7 1.50 1.50 18.63 203.33 101.67 4.58 1.44 160.67 1.02 l2×l8 1.50 1.67 19.21 190.00 96.67 4.92 1.55 160.67 1.02 l3×l4 1.50 1.50 14.49 178.33 88.33 3.42 1.10 168.33 1.14 l3×l5 1.17 1.33 18.65 190.00 100.00 4.89 1.65 170.33 1.28 l3×l6 1.00 1.50 17.49 215.00 98.33 4.35 2.41 170.00 1.82 l3×l7 1.50 1.50 14.43 201.67 103.33 3.84 1.17 168.33 1.12 l3×l8 1.17 1.17 19.97 221.67 115.00 5.39 1.87 169.67 1.42 l4×l5 1.50 1.50 19.16 183.33 80.00 4.83 1.72 163.67 1.00 l4×l6 1.33 1.33 16.74 210.00 98.33 4.16 1.17 141.67 1.23 l4×l7 1.50 1.67 18.05 196.67 95.00 4.43 1.44 167.67 1.11 l4×l8 1.50 1.50 16.03 218.33 108.33 4.10 2.08 164.67 1.11 l5×l6 1.50 1.83 17.59 206.67 101.67 4.09 1.57 164.33 1.07 l5×l7 1.50 1.50 18.80 191.67 95.00 4.63 1.10 168.33 1.01 l5×l8 1.17 1.17 18.56 200.00 108.33 4.63 1.00 164.67 1.55 l6×l7 1.33 1.67 18.13 198.33 100.00 4.72 1.64 169.33 1.35 l6×l8 1.83 1.83 16.29 125.00 60.00 4.51 1.60 170.33 1.01 l7×l8 1.67 2.00 14.47 151.67 85.00 3.67 1.00 163.67 1.63 bhqpy 1.17 1.33 19.74 203.33 101.67 5.67 1.00 169.00 1.79 mh138 1.50 1.67 16.11 160.00 78.33 4.24 1.01 163.33 1.36 cv 12.47 15.38 13.14 7.18 8.59 15.07 33.28 0.51 12.48 lsd 0.29 0.39 3.77 22.76 13.25 1.10 0.78 0.78 0.25 max. 1.83 2.00 19.97 221.67 115.00 5.67 2.41 170.33 1.82 mean 1.43 1.55 17.50 193.17 93.94 4.44 1.45 164.34 1.23 min. 1.00 1.17 14.43 125.00 60.00 3.42 1.00 141.67 1.00 note: a gy = grain yield; bm = biomass yield; da = number of days to anthesis; nkr = number of kernels per row; nkre = number of kernel rows per ear; ds = days to silking; tkw = thousand kernels weight; asi = anthesis silking interval; hi = harvest index; eh = ear height; el = ear length; epp =number of ear per plant; ph = plant height; dm = days to maturity; ed = ear diameter; el = ear length; er = ear rot; et= turciccum leaf blight and ps = puccinia sorgi (rust). ** = significant at p<0.01 level of probability; * = significant at p<0.05 level of probability. the crosses l6×l8, l7×l8, l1×l2, l4×l5, l2×l3 which have shorter plant height and medium ear placement, which are desirable for lodging resistance and to apply necessary management practices, whereas hybrids that were longer in ear and plant heights such as l3×l8, l4×l8 could be used as sources of genes for development of longer statured varieties to harvest high biomass yield that could be used as animal feed, fencing and source of fuel for resource poor farmers. the f1 crosses namely l1×l6, l2×l3, l6×l8, and l7×l8 display lower ear rot severity score. these show there are promising materials that are less affected by ear rot. based on their yield and overall performance, these materials could be advanced to advanced stages of trials to confirm their performance across locations and years. the low severity turcicum leaf blight was recorded for l3×l8, l5×l8; while the higher was recorded from l1×l2, l7×l8. generally, the tlb severity varied from low to moderate level. in the case of puccinia sorghi (common rust), the lowest severity was observed from l1×l4, l3×l6 and the highest was from l6×l8. woldu et al. standard maize heterosis 59 3.3. estimation of standard heterosis in the present study, the magnitude and direction of heterosis in f1 hybrids varied from character to character, and from cross to cross (table 4). the estimates of heterosis over the best standard check showed significant differences among genotypes for grain yield and yield related traits. thus, positive, and negative significant standard heterosis was observed in most of the genotypes compared with the two standard checks (bhqpy-545 and mh-138). this indicates the presence of considerable amount of heterosis for improving grain yield and yield related traits including disease reaction. these results are comparable with the reports of mahantesh (2006) and shushay (2014) who reported varying degree of heterosis for grain yield and its related traits in maize. table 4. estimates of standard heterosis for yield and yield related trait of maize inbred lines evaluated at haramaya, eastern ethiopia, during the 2017/18 main cropping season. crosses traits per inbred lines tested a gy el nkr nkre bhqpy545 mh138 bhqpy545 mh138 bhqpy545 mh138 bhqpy545 mh138 l1×l4 -1.08 22.40* -1.22 21.04* 16.90** 16.99** -12.09 11.62 l1×l6 -5.82 16.53* -10.39 9.81 9.28 9.37* -17.08 5.29 l1×l7 -16.49* 3.33 -22.49* -5.03 10.00* 10.09* -33.33** -15.35 l2×l3 -8.73 12.93 -2.68 19.24 2.73 2.81 -24.30* -3.87 l2×l4 -14.12* 6.27 -16.16* 2.73 9.10* 9.19* -16.14 6.48 l2×l5 0.54 24.40* 1.01 23.77* -0.08 0.00 -21.42* -0.22 l2×l7 -13.04* 7.60 -5.62 15.64 8.94* 9.03* -23.18* -2.46 l2×l8 -13.58* 6.93 -2.68 19.24 9.47* 9.56* -13.79 9.46 l3×l4 -1.72 21.60* -26.60** -10.06 9.47* 9.56* -43.72** -28.54* l3×l5 -14.33* 6.00 -5.52 15.77 10.69* 10.78* -22.71* -1.86 l3×l6 20.58** 49.20** -11.40 8.57 5.92 6.00 -34.27** -16.54 l3×l8 7.65 33.20** 1.17 23.96* 11.75* 11.84** -5.99 19.37 l4×l6 -1.40 22.00* -15.20 3.91 -0.45 -0.37 -27.58* -8.05 l4×l7 -15.95* 4.00 -8.56 12.04 11.94** 12.03** -31.34** -12.82 l5×l6 -17.13* 2.53 -10.89 9.19 12.65** 12.74** -34.57** -16.92 l5×l8 -5.17 17.33* -5.98 15.21 3.26 3.34 -27.29* -7.68 l6×l7 -3.56 19.33 -8.16 12.54 1.86 1.94 -22.89* -2.09 l6×l8 0.32 24.13* -17.48* 1.12 -24.48** -24.42** -27.70* -8.20 l7×l8 -5.71 16.67* -26.70** -10.18 2.20 2.28 -33.86** -16.02 se(d) 0.71 0.71 1.88 1.88 1.67 1.67 1.76 1.76 cd5% 1.19 1.19 3.16 3.16 2.80 2.80 2.96 2.96 cd1% 1.71 1.71 4.53 4.53 4.03 4.03 4.25 4.25 woldu et al. east african journal of sciences volume 14 (1) 51-64 60 table 4. continued crosses traits per inbred lines tested a dt ds ph eh bhqpy545 mh138 bhqpy545 mh138 bhqpy545 mh138 bhqpy545 mh138 l1×l4 -1.70 -0.86 -2.81* -0.41 4.100 32.29** 0.00 29.80** l1×l6 -1.27 -0.42 -2.81* -0.41 0.000 27.08** -11.48* 14.90* l1×l7 -0.85 0.00 -2.41* 0.00 -2.460 23.96** -8.20 19.15* l2×l3 4.23** 5.13** 2.41* 4.94** -11.47* 12.50* -18.04** 6.38 l2×l4 0.00 0.86 -1.61 0.82 -1.640 25.00** -11.48* 14.90* l2×l5 1.69 2.56* 0.00 2.47** 4.100 32.29** 3.28 34.05** l2×l7 -0.43 0.42 -2.01 0.41 0.000 27.08** 0.00 29.80** l2×l8 1.69 2.56* 0.80 3.29 -6.560 18.75** -4.92 23.41** l3×l4 -1.27 -0.42 -2.81* -0.41 -12.30* 11.460 -13.12* 12.77 l3×l5 -0.85 0.00 -2.41* 0.00 -6.560 18.75* -1.64 27.67** l3×l6 -2.12 -1.28 -2.81* -0.41 5.740 34.38** -3.29 25.53** l3×l8 -0.85 0.00 -2.41* 0.00 9.020 38.54** 13.11* 46.81** l4×l6 -2.97** -2.14 -4.01** -1.64 3.280 31.25** -3.29 25.53** l4×l7 0.00 0.86 -1.61 0.82 -3.280 22.92** -6.56 21.28** l5×l6 -1.27 -0.42 -2.81* -0.41 1.640 29.17** 0.00 29.80** l5×l8 -1.70 -0.86 -2.81* -0.41 -1.640 25.00** 6.55 38.30** l6×l7 -0.43 0.42 -2.01 0.41 -2.460 23.96** -1.64 27.67** l6×l8 5.92** 6.83** 4.42** 7.00** -38.52** -21.88** -40.99** -23.40** l7×l8 2.11 2.99** 0.40 2.88** -25.41** -5.21** -16.40** 8.52 se(d) 0.85 0.85 0.89 0.89 11.32 11.32 6.59 6.59 cd5% 1.43 1.43 1.49 1.49 19.01 19.01 11.06 11.06 cd1% 2.05 2.05 2.15 2.15 27.30 27.30 15.90 15.90 table 4. continued crosses traits per inbred lines tested a tkw epp dm bhqpy545 mh138 bhqpy545 mh138 bhqpy545 mh138 l1×l4 19.37 46.93** -14.53* 12.50 -0.79* 2.66** l1×l6 -13.09 6.98 -16.20* 10.29 -0.40 3.06** l1×l7 -18.40 0.44 -42.46** -24.26** -7.69** -4.49** l2×l3 2.27 25.88 -28.4** -5.88 -2.17** 1.22** l2×l4 -7.69 13.62 -35.20** -14.71* -3.55** -0.20 l2×l5 11.06 36.70* -35.75** -15.44* -0.59 2.86** l2×l7 -11.38 9.08 -43.02** -25.00** -4.93** -1.63** l2×l8 1.71 25.20 -43.02** -25.00** -4.93** -1.63** l3×l4 12.12 38.01* -36.31** -16.18* -0.40 3.06** l3×l5 -2.58 19.91 -28.49** -5.88 0.79* 4.29** l3×l6 25.75** 54.79** 1.68 33.82** 0.59 4.08** l3×l8 4.84 29.04* -20.67** 4.41 0.40 3.88** l4×l6 -4.34 17.75 -31.28** -9.56 -16.17** -13.26** l4×l7 -13.39 6.61 -37.99** -18.38* -0.79* 2.66** l5×l6 6.72 31.36* -40.22** -21.32* -2.76** 0.61 l5×l8 20.14 47.88** -13.41* 13.97* -2.56** 0.82* l6×l7 -1.29 21.50 -24.58** -0.74 0.20 3.67** l6×l8 7.28 32.05* -43.58** -25.74** 0.79* 4.29** l7×l8 -14.84 4.82 -8.94 19.85* -3.15** 0.21 se(d) 52.00 52.00 0.12 0.12 0.68 0.68 cd5% 87.31 87.31 0.20 0.20 1.14 1.14 cd1% 125.42 125.42 0.29 0.29 1.64 1.64 note: a gy = grain yield; el= ear length; nkr = number of kernels per row; nkre = number of kernel rows per ear; da = days to anthesis; eh = ear height; ph = plant height; ds = days to silking; epp = number of ear per plant; tkw = thousand kernels weight; dm = days to maturity; se (d) = standard error difference and cd = critical difference. ** = significant at p<0.01 level of probability; * = significant at p<0.05 level of probability. woldu et al. standard maize heterosis 61 number of ear per plant: the estimated heterosis of crosses over bhqpy-545 and mh-138 for number of ear per plant varied from -43.58% to 1.68%; and 25.00% to 33.82%, respectively. twenty-six crosses showed significantly lower number of ear per plant than bhqpy-545 while only one of the crosses (l3×l6) showed higher number of ear per plant than bhqpy-545. this indicates that this cross is highly prolific than the better standard check could be used to enhance grain yield. on the other hand, nine hybrids showed significantly lower number of ear per plant than mh-138 while three of the crosses showed significantly higher thousand kernel weights than mh138. days to maturity: the estimated heterosis crosses over bhqpy-545 and mh-138 for days to maturity varied from -16.17% to 0.79 % and -13.26% to 4.29%, respectively. eighteen hybrids revealed significantly earlier than bhqpy-545, which are desirable for the development of early maturing varieties than the checks and to adjust cropping pattern. however, two crosses showed significantly late maturity than the check bhqpy-545. on the other hand, nine hybrids revealed significantly lower days to maturity than mh-138, which are desirable for the development of early maturing varieties to escape drought or terminal moister stress and frost while fifteen hybrids showed significantly higher days to maturity than mh-138. plant height: standard heterosis estimates of crosses over the two commercial checks for plant height ranged from -38.52% to 9.02 % and -21.88% to 38.54%, respectively. among all the crosses, l1×l3, l3×l4, l6×l8 and l7× l8 showed significantly lower plant height than bhqpy-545 while none of the crosses showed significantly higher plant height than bhqpy-545. on the other hand, two hybrids (l6×l8 and l7×l8) showed significantly lower plant height than mh-138 while twenty-four hybrids showed significantly higher plant height than mh-138. generally, negative heterosis for plant height is desirable for breeding short statured hybrids and implied that these hybrids would resist lodging and mature earlier. on the other hand, the crosses which showed significantly higher plant height gave higher grain yield, which could be attributed to high photosynthetic products accumulation during long period for grain filling. these results agreed with the findings of shushay (2014); reddy et al. (2015); matin et al. (2017); and natol et al. (2017) who reported both negative and positive values of standard heterosis for plant height. ear height: standard heterosis of crosses over the two standard checks for ear height ranged from -40.99% to 13.11% and 23.40% to 46.81%, respectably. among the tested genotypes, nine hybrids exhibited significantly lower ear placement than bhqpy-545 while only one hybrid (l3×l8) showed significantly higher ear placement than bhqpy-545. on the other hand, one cross (l6×l8) showed significantly lower ear height than mh-138 while twenty-one crosses showed significantly higher ear height than mh-138 (table 4). generally, plant and ear heights are the major concern to maize breeders since plants with increased ear and plant heights are vulnerable to lodging and hence to yield reduction. on the contrary, low plant and ear height are desirable to reduce lodging problems in maize and for ease of mechanized operations. therefore, the variability existed in the tested crosses could help in the improvement of these traits. ear length: heterosis estimates of crosses over the two standard checks for ear length ranged from 26.90% to 1.17% and -10.43% to 23.96%, respectively. nine of the crosses showed significantly lower ear length compared to bhqpy545, while none of the cross showed significantly higher ear length than bhqpy-545. conversely, the crosses l1×l4, l2×l5 and l3×l8 showed significantly higher ear length than mh-138 while none of the cross showed significantly lower ear length compared to mh-138 (table 4). longer ears are desirable and can result in higher grain yield. these results agree with the finding of dhoot et al. (2017) who reported that none of the hybrid exhibited positive significant economic heterosis for ear length. on the contrary, natol et al. (2017) reported both negative and positive values of standard heterosis for ear length. number of kernels row per ear: the estimated heterosis of crosses over the two standard checks for number of kernels row per ear ranged from -35.15% to -4.75% and -28.54% to 20.94%, respectively. twentyone of the crosses showed significantly lower number of kernels row per ear than bhqpy545 while none of the crosses showed significantly higher number of kernels row per ear than bhqpy545. conversely, only one cross showed significantly lower number of kernel row per ear than mh-138 while none of the crosses showed significantly higher number of kernels row per ear than mh-138. these results were comparable with the finding of dhoot et al. (2017) who reported none of the tested hybrids exhibited positive significant economic heterosis for kernel row per ear. on the contrary, amiruzzaman (2010) reported both significant negative and positive values of standard heterosis for kernel row per ear. number of kernels per row: standard heterosis of crosses over bhqpy-545 and mh-138 for number of kernels per row ranged from -24.48% to 16.90% and 24.42% to 16.99%, respectively. among the genotypes, woldu et al. east african journal of sciences volume 14 (1) 51-64 62 fourteen crosses showed significantly higher number of kernels per row compared to bhqpy-545 while only two crosses showed significantly lower number of kernels per row than bhqpy-545. on the other hand, sixteen crosses showed significantly higher number of kernel per row compared to mh-138 while only one cross showed significantly lower number of kernels per row than mh-138. these results agree with the findings of reddy et al. (2015); and natol et al. (2017) who reported both negative and positive values of standard heterosis for number of kernel per row. thousand kernel weight: the estimated heterosis of crosses over the two standard checks for thousand kernel weight varied from -39.84% to 25.75% and 25.95% to 54.79%, respectively. among all two crosses showed significantly lower thousand kernel weight than bhqpy-545 while only one cross showed significantly higher thousand kernel weights than bhqpy-545. on the contrary, eight hybrids showed significantly higher thousand kernel weights than mh-138 while none of the crosses showed significantly lower thousand kernel weights than mh-138 (table 4). these results agree with the findings of amiruzzaman (2010), shushay (2014), reddy et al. (2015); ziggiju et al. (2016); matin et al. (2017) and natol et al. (2017) who reported both negative and positive values of standard heterosis for thousand kernel weight. grain yield: standard heterosis of crosses over the two standard checks for grain yield ranged from -57.22% to 20.58% and -47.07% to 49.20%, respectively. among the crosses, l3×l6 showed significantly higher grain yield compared to bhqpy-545 whereas sixteen hybrids showed significantly lower grain yield than bhqpy-545. on the other hand, ten hybrids exhibited significantly higher grain yield compared to mh-138 while five crosses showed significantly lower grain yield than mh-138(table 4). crosses which showed higher grain yield than the commercial standard checks are desirable for the improvement of maize grain yield by exploiting maximum heterosis. presence of positive and significant standard heterosis for grain yield was reported by berhanu (2009) and tajwar and chakraborty (2013). similarly, amiruzzaman (2013), melkamu (2013), shushay (2014), girma et al. (2015), matin et al. (2017) and natol et al. (2017) found significant positive and negative values of standard heterosis for grain yield. days to tasseling: heterosis estimates of crosses over the two standard checks for days to tasseling ranged from -2.97% to 4.65 % and -2.14% to 6.83%, respectively. thirteen hybrids showed significantly lower days to tasseling than bhqpy-545 which are desirable to develop early maturing hybrids while five crosses showed significantly higher days to tasseling than bhqpy-545. on the other hand, seven hybrids revealed non-significant negative value of standard heterosis for days to tasseling over mh-138 while ten hybrids showed significantly higher days to tasseling than mh-138. days to silking: the estimated heterosis of crosses over the two standard checks for days to silking varied from -4.01% to 4.42 % and-1.64% to 7.0%, respectively. among the crosses, ten showed significantly lower days to silking than bhqpy-545 towards the desired direction while only four crosses showed significantly higher days to silking than bhqpy-545 towards undesirable direction. on the other hand, seven hybrids revealed non-significant and negative value of standard heterosis for days to silking over mh-138 while nine hybrids showed significantly higher days to silking than mh-138. negative and significant standard heterosis for days to silking indicates that earlier silking is directly correlated with early maturity; and the reverse holds true for the positive heterosis. 4. conclusions the results of this study demonstrated that promising standard heterosis for grain yield was recorded for crosses l3×l6, l3×l8 over bhqpy 545. crosses l3×l6, l1×l4, l1×l6, l2×l5, l3×l4, l3×l8, l4×l6, l5×l8, l6×l8, and l7×l8 showed positive and significant standard heterosis for grain yield over mh-138, indicating the presence of high magnitude of standard heterosis over commercial checks which could be used in the maize breeding program to exploit the hybrid vigor. the crosses l1×l7, l2×l7, l2×l8 and l4×l8 are earlier than commercial check which could be useful for breeders in developing early maturing variety. in addition, maximum positive and significant standard heterosis was recorded for l3 × l6 and l1 × l4 for 1000 kernel weight and number of kernels per row, respectively, over bhqpy-545 and mh-138. these results indicate the possibility of obtaining high yielding commercial varieties with many desirable traits after confirming the results by repeating the research over years and across locations and thereby help in accelerating the rate of adoption of maize hybrids in the eastern ethiopia. in general, the information generated from this study could be valuable for researchers who intend to develop high yielding varieties of maize. therefore, future research should have to be directed towards the development of threeway crosses or double cross by selecting other good inbred lines as the third parent to improve the productivity of the crop. woldu et al. standard maize heterosis 63 5. acknowledgments the authors would like to thank haramaya university for its financial support. we are also grateful to haramaya university maize research program for providing the experimental materials. 6. references abate, t., shiferaw, b., menkir, a., wegary, d., kebede, y., tesfy, k., kassie, m., bogale, g., tadesse, b. and keno, t. 2015. factors that transformed maize productivity in ethiopia. food security, 7(5): 965-981. abiy balcha gebre, hussein mohammed and demissew abakemal. 2019. standard heterosis of hybrids maize (zea mays l.) for grain yield and yield related traits at kulumsa, southeastern ethiopia. international journal of research studies in agricultural sciences, 5(9): 1-7. amiruzzaman, m., islam, m.a., hassan, l. and rohman, m.m. 2010. combining ability and heterosis for yield and component characters in maize. academic journal of plant science, 3(2): 79-84. amiruzzaman, m., islam, m.a., hasan, l., kadir, m., and rohman, m.m. 2013. heterosis and combining ability in a diallel among elite inbred lines of maize (zea mays l.). emirates journal of food and agriculture, 25(2): 132-137. banziger, m. and diallo, a.o. 2004. progress in developing drought and n stress tolerant maize cultivars for eastern and southern africa. in: friesen, d.k. and palmer, a.f.e. 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methods. the iowa state college press, ames, iowa. usa, pp. 160-413. tajwar, i. and chakraborty, m. 2013. combining ability and heterosis for grain yield and its components in maize (zea mays l.) inbreds over environments. african journal of agricultural research, 8(25): 32763280). thiemann, a., junjie, f., felix, s., robert, t.g.-d., tobias, a.s., heike, p., matthias, f., albrecht, e.m. and stefan, s. 2014. genome-wide metaanalysis of maize heterosis reveals the potential role of additive gene expression at pericentromeric loci. bmc plant biology, 14(88). https://doi.org/10.1186/1471-2229-14-88. ziggiju, m., habtamu, z. and legesse, w. 2016. standard heterosis of pipeline maize (zea mays l.) hybrids for grain yield and yield related traits at pawe, northwestern ethiopia. international journal of plant breeding and crop science, 3 (2): 6-8. ©haramaya university, 2019 issn 1993-8195 (online), issn 1992-0407(print) east african journal of sciences (2019) volume 13 (1) 89-108 ______________________________________________________________ licensed under a creative commons *corresponding author. e-mail: mashilla.dejenewm@gmail.com attribution-non-commercial 4.0 international license. importance, biology, epidemiology, and management of loose smut (ustilago nuda) of barley (hordeum vulgare): a review mashilla dejene woldemichael school of plant sciences, haramaya university, p.o. box 138, dire dawa, ethiopia abstract: barley (hordeum vulgare) is an economically, nutritionally and industrially important cereal crop worldwide. ethiopia is believed to be the center of origin and diversity of the cultivated barley crop. the crop has been cultivated in the country since time immemorial. the midlands and highlands of ethiopia are suitable for barley cultivation. however, there are many biotic and abiotic factors that reduce production and productivity of the crop in ethiopia and elsewhere. of the various fungal plant diseases limiting barley productivity, loose smut (ustilago nuda) is one of the major cosmopolitan and destructive seedborne pathogen in many barley-producing countries in the world. this piece of work was undertaken to: 1) review the economic importance and ecological requirements of barley and extent of grain loss due to barley loose smut; 2) review the biology and ecological requirements of the pathogen leading to epidemics; and 3) compile the management options for sustainable barley production and productivity. to achieve these objectives, data and information were gleaned from scientific journal publications, phd dissertations, master’s theses, research reports, books and book chapters, proceedings and symposia papers, relevant compendia, internet resources, personal communications, and similar other resources. from the reviews made, it could be deduced that barley loose smut on average causes estimated grain yield losses that range from 25 to 30% in the world. the systemic pathogen is embedded in the scutellum part of the embryo and easily transmitted to the next cropping season. the pathogen sori commonly replace the spike during anthesis and healthy ears are infected at flowering through the teliospores blown by wind. warm soil when seedlings emerge is more conducive to loose smut than cold soil; however, moderate temperature (15 to 22 oc) and damp cloudy weather or heavy rainfall at flowering time are the preconditions required by the pathogen for heavy infection because of elongated or extended period of open flowers. barley loose smut can be better managed through the use of proper cultural practices in integration with hot water and solar heat seed treatment, use of resistant varieties, and effective systemic fungicides, like azoxystrobin, carboxin, difenoconazole, mancozeb, propiconazole, tebuconazole, triadimenol, and triticonazole. it could, thus, be concluded that barley loose smut is a very important disease that seriously affects barley production and productivity worldwide, but can be reasonably managed through the use of smut-free seed, certified seed, host resistance, and hot water/solar heat or systemic fungicidal seed treatment or their integration. keywords: barley; loose smut; seedborne fungi; seed treatment; ustilago nuda; yield loss. 1. introduction according to vavilov (1951), barley (hordeum vulgare l.) has a diversity of forms and genes and ethiopia is a center of origin for the crop. new studies supporting the polyphyletic origin of the crop also have indicated ethiopia as one of the centers of origin of barley (azebet al., 2016). barley cultivation probably began in the highlands of ethiopia and southeast asia in prehistoric times. remains of barley grains found at archaeological sites in the fertile crescent indicate that the crop was domesticated 10,000 years ago from its wild relative hordeum spontaneum (badr et al., 2000; zhou, 2010). also, the same scholars stated that the wild populations from israel-jordan are molecularly more similar than are any others to the cultivated gene pool. landraces from the himalayas and india indicate that an allelic substitution has taken place during the migration of barley from the near east to south asia and, thus, the himalayas and india are considered as regions of domesticated barley diversification (badr et al., 2000). accordingly, after detailed molecular characterization of 317 wild and 57 cultivated barley lines, badr et al. (2000) generally concluded that the israel-jordan area in the southern part of the fertile crescent has the highest probability of being the geographical area within which wild barley was domesticated; and wild populations found in the southern part of the fertile crescent in western iran have also contributed germplasm to the cultivated barley on its way to the himalayas. the barley cultivation time is believed to extend back to 5000 bc in egypt, 3500 bc in mesopotamia, 3000 bc in north-western europe, and 2000 bc in china (tiwari, 2010; zhou, 2010). the authors added that barley was the chief bread plant of the hebrews, greeks, and romans and of much of europe through mailto:mashilla.dejenewm@gmail.com mashilla east african journal of sciences volume 13 (1) 89-108 90 the 16th century. today barley is cultivated worldwide where the major producing countries are found in the temperate areas and in high elevations of the tropics and subtropics, including african countries, australia, canada, china, european union countries, india, iran, russia, turkey, usa, and others, where china, india, russia and usa are the major barley producers (zhou, 2010). eticha et al. (2010) also stated that barley has a long history of cultivation and diverse agro-ecological and cultural practices in ethiopia. barley is known to be an important staple food, industrial crop and animal feed worldwide, ranking fourth after wheat, maize and rice (asaad et al., 2014). it is a very important grain in the world today and it ranks fourth in both quantity produced and in area of cultivation of cereal crops in the world. the annual world harvest of barley from about 56.52 million hectares in the late century was approximately 140 million tons, with the average yield ranging between 2.50 to 4.00 tons per hectare during the period of spanning from 2001 to 2007 (tiwari, 2010; zhou, 2010). the world area under barley cultivation, annual production and productivity for 2016/17 cropping season were 49.28 million hectares, 147.06 million metric tons, 2.98 metric tons per hectare, respectively, while for 2017/18 cropping season the estimates were 47.81 million hectares, 143.68 million tons, and 3.0 metric tons per hectare, respectively(usda, 2019). similarly, the world area under barley cultivation, annual production and productivity during the 2018/19 cropping season were 49.23 million hectares, 140.71 million metric tons, and 2.86 metric tons per hectare, respectively (usda, 2019). in ethiopia, barley has been grown as one of the most important staple food crops in the mid-lands and highlands and was cultivated on 44,929.97 hectares of land and produced 110,813.15 tons of grain, with productivity of 2.47 t ha-1, during 2016/2017 main cropping season (csa, 2017). similarly, it was cultivated on 951,993.15 hectares of land and produced 2,052,996.372 tons of grain, with 2.16 t ha-1, during 2017/18 main cropping season (csa, 2018). the crop has a great value in the social and food habits of the ethiopian people, being used for preparing various types of foodstuffs (injera or flattened pancake, bread, porridge, muq, beso, kinche, chiko, and qolo) and local drinks (tela, borde and araqee) and industrial beverages (beer and malt products) (amare et al., 2014; wallelign et al., 2015; moanr, 2016). nutritionally, barley is rich in carbohydrates, with moderate amounts of protein, calcium and phosphorus (zhou, 2010). it is also a source of b vitamins, essential minerals and rich in fiber content, particularly beta-glucan, which has many health benefits (lowering blood sugar and checking cholesterol deposition for safety against heart ailments) (tiwari, 2010). in ethiopia, the straw is also used for thatching roofs, house-wall plastering paste mixed with mud, mulching, padding/bedding materials, fuel and animal feed, especially during the dry season (kuma et al., 2011; amare et al., 2014). based on its economic importance today, many barley varieties have been released, of which 37 food and 17 malt barley varieties are under cultivation in ethiopia, mainly produced in arsi, bale and showa (moanr, 2016). barley productivity in the country, however, is very low (2.47 t ha-1) (csa, 2017) compared to that of most other countries (3 to 4 t ha-1) (usda, 2019) due partly to biotic and abiotic factors and other factors influencing yields negatively. plant diseases, insect pests, weed competition, low-yielding varieties, soil fertility and reaction, climatic factors and poor farming systems are among the most important factors that reduce grain yield and quality of barley in ethiopia (amare et al., 2014) and elsewhere (mathur and jørgensen, 1992). today barley crop diseases cause or incur considerable yield and quality losses in ethiopia (wallelign et al., 2015). although many plant diseases are recorded on barley, scald (rhynchosporium secalis), net blotch (pyrenophora teres), spot blotch (cochliobolus sativus), leaf rust (puccinia hordei), stem rust (puccinia graminis f.sp. hordei), smuts (ustilago hordei and u. nuda) and eyespot (pseudocercosporella herpotrichoides) remain to be the most widely distributed and economically important diseases of the crop in ethiopia (getaneh et al., 1999; barc, 2000; marc, 2002; kiros, 2004; meki and asnakech, 2004), of which loose smut (ustilago nuda) is the major among the diseases (wallelignet al., 2017). the pathogen is a common cosmopolitan internally seedborne microorganism, whose mycelium is localized within the embryo. it spreads systemically and asymptomatically in the developing plant and the inflorescence is largely replaced during flowering or heading by sori containing teliospores and reducing yield and quality of harvested seeds for next planting (vánky, 1994). affected plants in the particular season cannot produce any grain. however, seeds infected by loose smut fungus produce undistinguishable normal and healthy-looking tillers up until the time of ear emergence (wallelign et al., 2015). in ethiopia, most farmers do not know the mechanisms of survival of the pathogen, how it infects the host plant, what factors favor the disease/pathogen and lead to epidemics over time, and how to fight the disease for sustainable barley production and productivity. exhaustive research information on barley loose smut is also limited for references by stakeholders. hence, reviewing and compiling pertinent aspects of barley loose smut and the causal pathogenic agent is of paramount importance. the general aim of this piece of work was to review the published research papers and professional books on barley loose smut and its management options during the past few years with especial reference to mashilla loose smut (ustilago nuda) of barley (hordeum vulgare) 91 ethiopia, providing information, research data and knowledge to end users (researchers, students, farming community, policy-makers and other stakeholders). the review was carried out with the specific objectives to: discern into the biology and ecological requirements for sustainable barley production; examine the economic importance of barley loose smut in ethiopia and elsewhere; compile the biology of ustilago nuda that causes barley loose smut; review the environmental factors suitable for ustilago nuda leading to epidemics; and review the possible management options against barley loose smut. 2. biology and ecological requirements for barley production 2.1. biology of barley barley (hordeum vulgare l. subsp. vulgare) belongs to the genus hordeum l. in the tribe triticeae of the family poaceae (gramineae) (zohary and hopf, 1993). the genus comprises more than 30 wild grass species distributed in the temperate and arid regions of the world. barley is most conspicuously characterized by its inflorescence that is a spike instead of the panicle that occurs in most other grasses. the wild progenitor of the cereal is h. vulgare subsp. spontaneum from southwest asia and it is easily crossable with its wild progenitor (forming the primary gene pool of barley). barley’s secondary gene pool is of little value; but the tertiary gene pool holds traits for pathogen resistances and adaptations to extreme environmental conditions, which are of high value if they can be transferred into cultivated barley or other cereals (blattner, 2018). the greatest food and malt barley diversity in morphological types, genetic races, disease resistant lines, and endemic morphotypes exists in ethiopia since ancient times (moanr, 2016). according to tiwari (2010), barley plant has several cylindrical culms with hollow internodes separated by solid nodes; and typically with 5-7 internodes on a culm (60–120 cm tall). the single leaves consist of tubular sheath and blade, are borne alternately on opposite sides at each internode, where the leaf sheath encases the culm and extends from the node to which it is attached to almost the whole length of the next internode. at the junction of the sheath and the blade, two colorless or pigmented lateral projections, called ‘auricles’ or ‘claws’, are also formed and the leaf-blade is long, flat and narrow with parallel veins. the barley’s flower (inflorescence), commonly called ‘ear’ (spike of spikelets), is distinguishable into two morphological types – six-rowed and two-rowed (photo 1). photo 1. matured 6-rowed barley ear (a); green 6-rowed ear (b); 2-rowed ear with sterile lateral spikelets (c); and 2-rowed ear with rudimentary lateral spikelets (d). (tiwari, 2010). mashilla east african journal of sciences volume 13 (1) 89-108 92 2.2. ecological requirements for barley production barley is a very versatile crop in every way and has been well adapted through its evolution. much of the world’s barley is produced outside of the regions where cereals, such as maize and rice, can grow well, extending into the arctic or subarctic areas (zhou, 2010). cultivated barley is grown in a range of diverse environments that vary from subarctic to sub-tropical, with greater concentration in temperate areas and high altitudes of the tropics and subtropics. it is also found in most areas with mediterranean climate too (zhou, 2010). other than the cool highlands, barley is rarely grown in the tropics as it is not suited to warm humid climates (nevo, 1992). generally barley has a wider ecological range than any other small cereal crops (bukantis and goodman, 1980). annual rainfall of 190 to 1760 mm, annual temperature ranging from 4.3 to 27.5 °c and soil ph of 4.5 to 8.3 are suitable for barley production and does well on light or sandy loam soils (duke, 1983). barley grows well at altitudes of 1500 to 3500 meters above sea level (m.a.s.l.) and is predominantly grown at 2000 to 3000 m.a.s.l. in ethiopia (moa, 1998). in the country, barley is commonly cultivated twice a year, i.e. during belg (short rainy period from march to may) and meher (long rainy season from june to october). the major barley-producing regions in the country are amhara, oromiya, southern nations, nationalities and peoples’ and tigray regional states (moanr, 2016). 2.3. agronomic practices and harvesting duke (1983) stated that the seedbed for barley sowing should be prepared to good tilth and the seed is sown by broadcasting or drilling in shallow furrows about 22 cm apart. the recommended depth of sowing is 1.3–4.5 cm. seeding rates could vary from ca. 65 to 100 kg ha-1. the crop may be raised under both rainfall and irrigated conditions. in dry areas, two to three times watering may be required after sowing. application of fertilizers containing nitrogen, phosphorus or potash, in various combinations, would influence yield and quality of grain. the recommended blanket fertilizer rates for small cereals in ethiopia are 46 kg p2o5ha-1 and 41 kg n ha-1 (moanr, 2016). additional nitrogen increases yield of straw and grain, but in larger doses, nitrogen increases the protein content and negatively affects its brewing quality. phosphate fertilizers lower the protein content considerably and influence formation and ripening of grain. weeding practices are done manually, using mechanical means and/or use of herbicides (commonly selective herbicides). harvesting and threshing are done manually in developing countries and combine harvesters are employed in developed countries. however, the crop is very prone to smuts under barley production systems of ethiopia. 3. economic importance of barley loose smut barley is affected by three smuts, namely covered smut (ustilago hordei), black semi-loose smut (ustilago nigra) and loose smut (ustilago nuda) (asaad et al., 2014). according to these authors, covered smut and black semi-loose smut are due to surface-borne (externally seedborne) pathogens that infect emerging seedlings and develop systemically, while loose smut infects barley during flowering and survives systemically as dormant mycelium in the seed embryo. loose smut is virtually widely distributed throughout the world and found everywhere in places where barley is grown (afanasenko et al., 2004; afanasenko, 2009; johnson, 2014; zang, 2017). 3.1. yield and economic losses of barley due to loose smut root, foliar, and head plant diseases, like smuts, commonly account for yield losses of up to 20-30% (evans, 1999). barley loose smut is an internal seedborne disease found wherever barley is grown and is a serious threat to crop yields (larter and enns, 1962; malone and muskett, 1964) and is due to infection that results in replacement of inflorescence by teliospores of the pathogen (bailey et al., 2003). this monocyclic disease is known to cause crop yield losses, which are approximately equal to the percentage of infected plants within a field but with little or no effect on seed or grain quality (menzies, 2008; johnson, 2014). for example, a 5% infection generally leads to a 5% yield reduction; however, occasionally highly susceptible varieties sustain losses in excess of 30% due to the high carry over initial inocula embedded in the embryos (sherwood, 1997). grain losses less than 1% are reported in the literature in modern times; but losses of 15 to 25% can occur in the absence of proper management practices (wallelign et al., 2015). the incidence of loose and covered smuts had previously decreased substantially in north america and european countries as a result of use of more effective seed treatment systemic fungicides, and use of more resistant varieties (zillinsky, 1983). however, barley yield losses of 10 to 30% due to loose smut are still common and encountered in some countries (zang, 2017). previously, bekele et al. (1994) reported an incidence of 28% for barley loose smut in western amhara, ethiopia. furthermore, a field survey conducted in awi, south gondar and west gojjam zones of ethiopia in 2014 indicated a loose smut incidence ranging from 4.04 to 10.64% at field level, whereas seed samples showed a maximum infection of 25.65%, which was actually too high to tolerate (wallelign et al., 2015). similarly, tolessaet al. (2015) reported a 20% loose smut severity on major cereal crops (including barley) in borana zone, ethiopia. from thisevidence, one can conclude mashilla loose smut (ustilago nuda) of barley (hordeum vulgare) 93 that barley grain yield loss due to loose smut in ethiopia ranges from ca 5 to 25%, varying with location, inoculum level in the seed used for planting, the barley variety, weather conditions and level of management practices. if we assume that a hectare of barley yields 3,000 kg grain and if there is 20% loose smut severity, the grain yield loss from the hectare of barley harvested would be (3,000x20)/100 = 600 kg. if the current price of 1 kg grain on market is etb 20, then the economic or financial loss due to loose smut per hectare would be 600 kg x etb 20 = etb 12,000, which is so high that smallholder barley growers cannot afford to tolerate. 3.2. symptoms and host ranges of barley loose smut barley loose smut symptoms commonly appear at the flowering stage and become apparent at heading or boot stage (asresie et al., 2015; davis and jackson, 2017). the meristematic tissue plays an important role for the passive spread or distribution of the pathogen within the plant by invasion (koch et al., 2013). the symptoms become obvious between heading and maturity and barley heads are initially black to dark brown and some diseased heads may be taller than any of their healthy neighbors. while most affected heads emerge slightly earlier than the normal ones, their spikelets may be entirely transformed into a dry, olive brown teliospore masses in the sori (photo 2 and 3) (neate and mcmullen, 2005; afanasenko, 2009; johnson, 2014; hills, 2018). under some environmental conditions, striated sori may also develop on the flag leaves, sheath, and culms of certain varieties (sherwood, 1997). photo 2. typical symptoms of barley loose smut at flowering stage of the crop, showing rachis covered with sori of the pathogen (hills, 2018). photo 3. symptoms of barley loose smut at heading (a); with sori completely replaced the ear (b); smutted heads mixed with healthy ears (c); close-up view of healthy and smutted heads (d) (johnson, 2014; thomas et al., 2017). generally, loose smuts are host specific with their own particular forma specialis (f.sp.). for example, loose smut of wheat does not infect barley or oats (thomas et al., 2017). the pathogen causing barley loose smut is an obligate monocyclic parasite and attacks cultivated barley and other hordeum species (neate and mcmullen, 2005), wheat, oats, rye, triticale and many other grasses, of course, with the respective forma specialis (menzies, 2008; menzies and gaudet, 2009). 4. biology of ustilago nuda thomas et al. (2017) stated that infected seed shows no symptoms and appears normal. but when infected seed germinates, the fungus becomes active again and grows slowly in the growing point of the plant. diseased a b c d mashilla east african journal of sciences volume 13 (1) 89-108 94 plants appear to grow normal but may be slightly taller and earlier maturing than surrounding healthy plants; and at heading, the fungus forms a compact spore mass to replace all florets within the cereal heads. 4.1. taxonomic classification of the pathogen the pathogen belongs to the class basidiomycetes, order ustilaginales, family ustilaginaceae, genus ustilago and species ustilago nuda (afanasenko, 2009). basidiomycetes are characterized by the sexual spores known as teliospores. upon germination, the teliospores produce four-celled basidia or promycelia. however, unlike the basidia of barley covered smut fungus (ustilago hordei), the basidia of ustilago nuda do not form the sexual spores known as ‘basidiospores’ or ‘sporidia’.ustilago nuda f.sp. hordei resembles ustilago segetum f.sp. segetum (syn. ustilago nuda f.sp. tritici) of loose smut fungus of wheat in almost all important features though it is not as common as loose smut of wheat and covered smut (ustilago hordei) of barley (malone and muskett, 1964; singh, 1982; french and schultz, 2009; menzies et al., 2014). a number of physiologic races of the fungus are known to occur and some host varieties exhibit a high degree of resistance (malone and muskett, 1964).however, two physiological races (a virulent, capable of overcoming the recessive resistance gene present in differential variety, and fungicide‐tolerant races) were identified in ireland in 1984 (dhitaphichit and jones, 1991) and existence of some more races are expected in other countries. the authors also reported that several crops grown from seed treated with vitavax (active ingredient carboxin), which had been imported from france, contained a carboxin-tolerant race of u. nuda. the ustilago nuda f.sp. hordei fungus produces a hyaline, dikariotic mycelium in host tissue (sherwood, 1997) and, at maturity, the hyphae of the mycelium thickens and fragments into teliospores (chlamydospores), which are olive brown by transmitted light, paler on one side, sub-spherical or globose, to ovoid, shortly spiny, and covered with very thin membrane and 3.6-10.0 m (most often 5.5-6.0 m) in diameter and minutely echinulate (zillinsky, 1983). the teliospore germinates to form a basidium and compatible basidial cells or short hyphae produced by the former fuse to form infectious dikaryotic mycelium (sherwood, 1997; afanasenko, 2009; asaad et al., 2014). it is also noteworthy that ustilago nuda does not form basidiospores (sporidia) during germination on artificial media (zillinsky, 1983; sherwood, 1997). generally, ustilago spp. can be grown on artificial media, but the rate of growth of such colonies is relatively slow and the use of the colony appearance as diagnostic feature in routine seed health testing would be of little or doubtful value (malone and muskett, 1964). thus, the pathogen behaves like obligate microorganism when attempted to cultivate it on artificial media. physiologic races of ustilago nuda exist and can hybridize to produce new races, but the biology of the organism makes this a slow process. host plant resistance is usually conditioned by dominant genes. in some cases, modifier genes may function together with the dominant genes in conditioning resistance (sherwood, 1997). unfortunately, some of these genes have been overcome, on a gene-for-gene basis, by recessive genes in the pathogen (menzies, 2008).however, adequate studies are not made on the presence or absence of physiological races of the pathogen in ethiopia. similarly, extensive researches have not been conducted to identify barley resistant/moderately resistant varieties regardless of the presence of several released and cultivated varieties (over 54 cultivars) in this country. even the presence or absence of the pathogen or extent of seed embryo infection is not easily determined before sowing or planting since such service is not accessible to the farming communities in the country. as a result, comprehensive studies are required to better understand the characteristics of the pathogen and its physiologic races in ethiopia and elsewhere. genetic investigations and molecular characterization are appealing for plant breeding activities in the efforts to develop resistant varieties against u. nuda. 4.2. pathogenicity/pathogenesis of ustilago nuda floral infection is initiated by teliospores landing on the open flowers (zillinsky, 1983). ustilago nuda teliospore germinates and infects developing seed embryo in the host flower and survives to the next host generation as dormant mycelium in the embryo of the seed (bailey et al., 2003; french and schultz, 2009). hence, u. nuda can be described as an internally seedborne pathogen since it is carried systemically in the infected seed (zillinsky, 1983; french and schultz, 2009). when infected seed is sown, the seed germinates and the fungus also grows systemically within the seedling colonizing meristematic tissue; later, the mycelia reach maturity when spikes develop, producing smutted heads (french and schultz, 2009). the mycelium of u. nuda breaks dormancy when the barley seeds germinate (menzies et al., 2014). that means, when infected seeds germinate, the fungus is stimulated to grow to the growing point and quickly ramifies and moves into the shoot apex, crown node or culm nodes, and seed primordia (french and schultz, 2009; johnson, 2014; menzies et al., 2014). as the barley plant grows and eventually ‘shoots’ to produce its ears, the fungus is carried upwards in the inflorescence that is converted into sori covered with fragile pericarp membranes, which would easily rupture and release the teliospores for spread and next infection (jones, 1999). the mycelium of u. nuda is specifically embedded in mashilla loose smut (ustilago nuda) of barley (hordeum vulgare) 95 the scutellium tissue of infected seeds, colonizing the embryo largely intercellularly, within the infected plant, being found particularly in the nodes and the ear (batts and jeater, 1958). the released teliospores alight on open flowers or developing grains and cause infection by growing through the ovary wall (sherwood, 1997). in this way, the mycelium,which develops sporiferous hyphae, penetrates all spikelet tissues except the rachis and the awns (shinohara, 1976; jones, 1999). at flowering, the teliospores are blown away by wind from the infected spikes and infect spikes of healthy plants where the spores settle in healthy flowers into which they germinate and infect the embryo at the same time of pollination of the developing grain (yahyaoui et al., 2003; french and schultz, 2009). mild temperatures and humid conditions facilitate spore germination and penetration of the ovary by germ tube, developing a mycelium in the embryo (french and schultz, 2009). the dikaryotic infection hyphae proceed between and through the cells to the developing embryo and become established (sherwood, 1997; afanasenko, 2009; koch et al., 2013; asaad et al., 2014). in the meantime, the mycelium remains dormant in the asymptomatic seed until the seed germinates at planting in the next crop season (french and schultz, 2009). in some barley varieties that exhibit physiological resistance, the fungus may become established in the embryos but diseased plants do not develop (hewett, 1979). 4.3. life cycle/disease cycle of ustilago nuda barley loose smut has relatively uncomplicated disease cycle and there is no spread between plants during the crop growth period, i.e. it is a monocyclic disease the relationship between seed infection and plant is relatively constant and it is only at flowering stage when seed re-infection takes place that environmental conditions influence disease development (jones, 1998). ustilago nuda attacks barley and wheat without any obvious effect on the vegetative growth (hewett, 1978). the infected seed develops normally, but contains the fungus as dormant mycelium inside the embryo (koch et al., 2013; menzies et al., 2014). the life cycle of u. nuda comprises of primary infection at flowering, survival in the form of spores/mycelium inside the seed, secondary infection in form of systemic infection at seedling stage upon germination and prior to emergence; symptom expression with smutted heads at flowering, releasing the teliospores; and their dissemination by wind (figure 1) (yahyauoi et al., 2003; johnson, 2014). the teliospores germinate and the resulting hyphae penetrate the developing seed to complete the life cycle (menzies and gaudet, 2009). upon germination of the teliospores, their long, delicate, infection hyphae enter the young ovary of the flower and grow deeply into embryo of the developing seed, but do not kill it. as the grain matures, the loose smut fungus becomes dormant until the following growing season (zillinsky, 1983). when the infected barley seed germinates, the fungus grows systemically within the new plant as secondary infection. as the barley plant approaches heading, the mycelium penetrates the head tissues and converts them into masses of teliospores (zillinsky, 1983). germinating teliospores produce a four-celled promycelium that, in turn, forms branches. the branches elongate, fuse, and rebranch to form mycelium. however, basidiospores are not produced in ustilago nuda (dcs-unill, 1990). furthermore, the infected seeds cannot be distinguished from healthy seeds by visual inspection only (jones, 1998). 4.4. survival and transmission of the pathogen ustilago nuda survives from one growing season to the next or between crop cycles as a dormant mycelium only in the endosperm and within the embryo of infected barley seeds, and the fungus can survive longterm storage of the seed (french and schultz, 2009; koch et al., 2013; asaad et al., 2014; johnson, 2014). during the formation of the sori, the hyphae differentiate and fragment into teliospores. then the sorus membrane breaks down shortly after the heads emerge and frees the teliospores for dispersal by rainfall splashes, insects, wind or other agents (afanasenko, 2009; johnson, 2014; menzies et al., 2014). menzies et al. (2014) also indicated that the teliospores are wind dispersed to infect the florets during flowering in case of loose smut or infest the next generation of barley seed at harvest in case of surface-borne covered or semi-loose smut pathogens. most inocula for loose smut re-infection probably originate within diseased crops and, given suitable conditions at flowering, the disease tends to multiply over successive generations (asaad et al., 2014). several authors indicated that infection can spread between neighboring crops and seeds developing in healthy barley crops could become infected by teliospores released in diseased crops 200 m upwind (french and schultz, 2009; asaad et al., 2014). however, most infections probably occur within 10 m of heads releasing teliospores (sherwood, 1997). infected volunteer barley plants can also act as an important inoculum source for developing seeds (french and schultz, 2009). mashilla east african journal of sciences volume 13 (1) 89-108 96 figure 1. life cycle of loose smut (ustilago nuda) showing different stages (kelly et al.,2015). 5. epidemiology of barley loose smut 5.1. ecological requirements according to dcs-unill (1990), a warm soil when seedlings emerge seems to be more conducive to loose smut than a cold soil. a heavy infection in the field will often mean a fairly heavy infection in the next crop season. however, even fields with a light infection sometimes produce seed with a high percentage of loose smut. cool and damp weather at flowering time is necessary for heavy infection because of elongated or extended period of open flowers. barley loose smut is most common in cool high rainfall areas and may be more common in the year following a wet spring, which promotes seed infection (asaad et al., 2014). cool, wet, cloudy weather and moderate temperatures (ranging from 15 to 22 oc) conditions promote longer and more open flowering for the host, allowing more time for teliospores to land on florets and germinate into floral tissue (sherwood, 1997; johnson, 2014). also, a single heavy rain during flowering in affected fields can cause a 10-20-fold increase in infection. similarly, frequent and high rainfall showers and high humidity at flowering favor infection and lead to development of loose smut epidemics in a susceptible barley variety (thomas et al., 2017). but excessive heat or dry air will lower germination and germ tube growth into the floral tissue, delay penetration of the ovary and preclude the fungus from reaching the growing point (danko and michalikova, 1969). 5.2. assessment of barley loose smut according to dcs-unill (1990), the percentage of loose smut infection in a crop of barley depends on how many of the seeds were initially infected in the field the previous cropping season, which, in turn, is determined by (1) the percentage of infection in the field during the previous season, (2) the weather conditions at the flowering time, and (3) the barley variety. in the field, infection levels are scored as percentage plant infection. any plant with one or more smutted ears (completely or partially smutted) is recorded as infected (jones, 1999). a field survey was conducted in five districts of three zones of western amhara region (ethiopia) in 2014 main cropping season to assess the level of barley loose smut (wallelign et al., 2015). the findings of this study revealed that the incidence ranged from 1.17 to 10.64% and district mean incidence of loose smut varied from 2.91 to 4.52%. increasing safe seed movement at the international level necessitates specific solutions to recognize the pathogen at the laboratory level and so reduces the use of fungicide seed treatments and seed health testing is the first step in the pursuit of healthy crops (asaad et al., 2014). detection of u. nuda in barley seed stocks is routinely done by an embryo test method (malone and muskett, 1964; rennie, 1990). the whole embryo count method using staining technique was first applied to cereal loose smut mycelium by skvortzov (1937) who dissected out the embryos, macerating them in sodium hydroxide and staining with aniline blue (neergaard, 1979). however, the complete procedures for embryo teliospores land on flowers of healthy plants and infect developing grain grain sites replaced by masses of teliospores mycelium invades the grain sites mycelium follows growing point of wheat/barley plant mycelium invades part of embryo in seed mashilla loose smut (ustilago nuda) of barley (hordeum vulgare) 97 count method are outlined by malone and muskett (1964), ista handbook no. 25, and ista (2014). according to malone and muskett (1964) and neergaard (1979), many workers modified this procedure later, mainly by developing chemical methods for separating the embryos so that many seeds could be tested on a routine basis. the embryo count method employed by malone and muskett (1964) is outlined as follows:  first 1000 to 4000 seeds (100 – 120 g) are taken and covered with or soaked in 1 l solution of 5 10% (usually 5%) sodium hydroxide (naoh) or concentrated sulphuric acid in a flask, (or placing the seeds in a shallow layer in a large glass dish with 20 cm diameter instead of a flask and using a larger quantity of sodium hydroxide, i.e. 650 ml for 40 g of seed); shaken thoroughly and allowed to remain overnight (24 hours) at 22 oc to extract the embryos (three replications recommended);  the contents of the flask are washed on the following day with warm running water or spraying hot water on the mixture through a series of sieves or 10 mesh sieve (hole sizes 3.5, 2.0, and 1.5 mm stacked sieves) to separate the embryos from the glumes and endosperm; (embryos and debris may be further separated after removal from sieves by using funnel containing 50% lactic acid, where the embryos float on the surface and some of the debris sink to the bottom);  collecting most of the embryos in the bottom sieve, with a few in the middle one; and placing them in a shallow dish of water to wash the embryos in the beaker and removing the embryos by means of a pipette with a rubber teat; (a small perforated spoon may be used for transferring the embryos instead of using a pipette);  placing the embryos in a small beaker and after draining off excess water, adding lactophenol;  clearing the embryos by heating on a water bath or fenwich can or in narrow mouthed bottle using hot water (at 60 – 65 oc, usually 50 oc) or by boiling in lactic acid and glycerol (1:2);  dehydrating the embryos into a beaker by soaking for 2 min in 95% ethanol;  placing them in a 10% koh and clearing by heating for 5 – 10 minutes;  examining the embryos through a stereoscope microscope (25 60x magnifications) and compound microscope for checking mycelium using transmitted light. the dark fungus mycelium can be seen in infected embryos without the use of stain;  the embryos are also examined by placing them in a petri dish marked with a series of parallel lines 1 cm apart; this method dispenses with the special perspex tray; and  mount embryos in lactophenol and examine using a microscope – bluish mycelium should be visible in the scutellum of infected seed. n.b. the per cent loose smut in the sample should be calculated based on the number of embryos examined but not on the basis of the number of seeds soaked. in some areas, tests for embryo infection (including the embryo count method) are used to determine in the laboratory the proportion of infected seed in the seed lots (sherwood, 1997; clark and cockerill, 2011). to detect loose smut (u. nuda) infection in cereal seeds requires detailed microscopic examination of at least 1000 individual embryos, which is actually a laborious procedure even with recent refinements, such as the use of sensitive fluorescent stains to visualize the pathogen (lucas, 1998). the complete procedures for detection of embryo infection by ustilago nuda has been developed and presented by ista (2002) and clark and cockerill (2011) for end users employing the embryo count method. similarly, a new and more rapid detection method for barley loose smut was developed at icarda – reducing the test period from two days to just five hours (asaad et al., 2014). the authors outlined that the methodology involves soaking 2000 barley seeds in sodium hydroxide (naoh) and then heating them at 40 °c for 3.5 hours. this is followed by pre-separation with sodium chloride (nacl) solution for 15 minutes and then collecting the embryos on 0.71 mm mesh. afterwards, the embryos are separated using a nacl solution, with a mixture of 1:1 glycerol and water. the embryos are then checked under the compound microscope for golden brown mycelium, which is indicative of infection of the embryo by ustilago nuda. the new method is fast, simple, reliable and very sensitive. the researchers concluded that the test result can be used by seed health laboratories and regulatory and quarantine authorities to ensure that only loose smutfree seeds are introduced (assad et al., 2014). the new and fast method developed by icarda for u. nuda detection clearly shows infected embryos in infected barley seeds (asaad et al., 2014). these researchers disclosed that the new method is fast, inexpensive, healthy (no harmful chemicals are used, nor a fume hood), simple, reliable and very sensitive; and they confirmed that results obtained are highly practical, accurate and cost effective, and will facilitate a quick judgment on the presence of u. nuda in infected seeds. this tool can rapidly detect the presence of u. nuda and is an advantage for routine seed health testing laboratories that conduct tests on large numbers of samples. the scholars recommended that this new method be used in seed health laboratories for research mashilla east african journal of sciences volume 13 (1) 89-108 98 and quarantine purposes to ensure that only seeds free of loose smut are introduced and planted, and it will play an important role in restricting the spread of this disease via infected seeds. practically, a laboratory seed health test was conducted using farmers’ saved local barley variety seeds (both twoand four-rowed seeds) collected from 15 farmers’ associations in western amhara region (ethiopia) in 2014 with the specific objective to determine the infection levels using the embryo count method employed by ista (2014). the results of the laboratory test indicated that the minimum (8.35%) barley loose smut infection and the maximum (25.65%) infection with the mean (17%) seed infection were recorded across the whole seed samples collected from the study areas for embryo examination (table 1) (wallelign et al., 2015). in this respect, the researchers mentioned that the local barley varieties, namely awuragebis and semerieta, were more dominantly infected than the other local varieties. however, when the results were compared with the field survey results, the laboratory results (loose smut infections) were found to be higher than the field survey results. the development of an effective, rapid and accurate method for detecting the pathogen is advantageous for rapid decision-making at seed health laboratories and quarantine centers and for minimizing the spread of loose smut (asaad et al., 2014). in the 1980s, new diagnostic technologies based on serological characters became available in plant pathology and have been successfully applied to seed testing (asaad et al., 2014). additionally, during the last 15 years, new techniques have been developed for detecting microorganisms in seeds, based on dna analysis (hollomon, 1998; asaad et al., 2014). barley loose smut is managed mainly by using healthy seeds or seeds coated with systemic fungicides; however, seed treatment is not recommended in many countries when the threshold is not exceeded, i.e. beyond 5% infection (asaad et al., 2014). moreover, the authors stated that because seed infected by loose smut can germinate and there are no visible signs to alert users to the pathogen, if the seed is not tested there is a high chance of introducing infected seeds into farmers’ fields or new areas. this implies that seed health testing prior to planting is necessary in areas where loose smut is a threat for barley and wheat production. 5.3. barley loose smut monitoring and forecasting disease monitoring provides information that lays the basis for forecasting system. in barley loose smut monitoring, it enables to inspect the presence or absence of the disease under field conditions, allowing rogueing measures if smutted spikes are detected early in the growth period. similarly, it ensures freedom of the seed from loose smut for next season sowing. table 1. welch’s variance-weighted anova for embryo test on barley seed infection with loose smut from five districts of western amhara region, ethiopia, during 2014 main cropping season. district location/farmers’ association barley variety mean infection (%) standard deviation farta kimirdengia awuragebis 25.65 (1.44) 0.019 lay gayint nefasmewucha tsebel 14.40 (1.21) 0.025 farta ata sifatira tsebel 20.10 (1.33) 0.007 lay gayint titramichael semerieta 12.00 (1.14) 0.039 lay gayint chekoho awuragebis 13.00 (1.18) 0.016 lay gayint genboche awuragebis 13.00 (1.18) 0.036 lay gayint govgov tikurdiribgebis 11.95 (1.10) 0.013 lay gayint sali awuragebis 16.55 (1.29) 0.064 sekela ambisi wonteka 20.96 (1.34) 0.006 sekela gindatemam semerieta 9.90 (0.97) 0.098 sekela ateta wonteka 15.05 (1.25) 0.063 yilmanadensa aybar semerieta 11.25 (1.11) 0.028 yilmanadensa debremawi semerieta 21.40 (1.36) 0.008 farta tsegur tsebel 11.00 (1.10) 0.032 guagusashikudad addisalem semerieta 8.35 (1.00) 0.044 mean ----14.97 -- cv (%) ----3.47 -- se () ----0.025 -- r2 ----0.95*** -- p-value ----<0.0002 -- where: cv = coefficient of variation; se = standard error; and values in parentheses are log transformed data (wallelign et al., 2015). mashilla loose smut (ustilago nuda) of barley (hordeum vulgare) 99 for barley loose smut diagnosis, it has been suggested to look for scattered plants with black heads or bare flower stalks unlike the covered smut; detection of slightly taller and earlier maturing than the heads of the surrounding healthy plants; having insight into compact masses of dark brown-black powdery spores at heading florets and remnant bare stalks once fungal spores have been blown away (jayasena and thomas, 2015). in this connection, one can identify the susceptible varieties from the resistant varieties in the monitoring process in the field. the percentage of smutted spikes in the plant stands in a particular season can be calculated during the monitoring process and field trials too (neergaard, 1979). the loose smut monitoring actually deals with detection of the percentage of embryo infection of seeds by u. nuda using an easy, rapid and precise routine testing method(s) (ista, 2016). this information is helpful for decision-making with reference to the need for seed treatment. similarly, knowledge of the soil moisture status at planting and the weather conditions at flowering helps for prognostication of loose smut for rogueing purpose. information on the genetics of the barley variety during monitoring is also desirable for prior action (borgen, 2004; menzies et al., 2009; menzies et al., 2010). generally, the disease assessment and prediction or forecasting process has been illustrated diagrammatically (figure 2) (lucas, 1998). 5.4. use of information technology in barley loose smut warning system in barley loose smut management, information technology can help in providing available information on the nature of the pathogen, how it causes the disease and the ecological conditions that lead to epidemics. animation of the processes of pathogenesis is useful for training farmers on the pathogen and knowledge on the disease itself. similarly, it can assist in public awareness creation on availability of the resistant varieties, and sorting susceptible varieties. the information on the loose smut management options is another area where information technology can help the farming communities, particularly in the use of integrated loose smut management by combining the efficient, economical and feasible management tactics. updating users on the latest technologies with reference to newly developed and released varieties, new systemic fungicides as well as new approaches on the detection of the systemic pathogen in the embryo. estimation of grain losses due to loose smut and modeling is also desirable. figure 2. activities involved in disease assessment and prediction (lucas, 1998). 6. barley loose smut management options barley loose smut can be well managed through the use of smut-free seed, certified seed, host resistance and hot water/solar heat or systemic fungicidal seed treatment or their integration (bailey et al., 2003; menzies, 2008). management measures can reduce yield losses occurring from loose smut even in areas where development of the pathogen is favored by the environmental conditions and susceptible varieties (sherwood, 1997). 6.1. cultural practices the cultural practices against loose smut include use of high quality and healthy clean seed produced in smutfree area, hot water treatment, irrigation just after planting to lower soil temperature and allow faster seed germination and emergence, rotating barley varieties from season to season, at least after three to four consecutive years, using optimum isolation distance and rogueing smutted spikes as soon as observed (evans, 1999; french and schultz, 2009; wallelign et al., 2015). growing barley continuously on the same plot results in significantly reduced yields and lower quality grain, especially in the wetter, higher yielding areas (evans, 1999). the author suggested that producers growing barley on the same farmland season after season or using short crop rotations will need to pay special attention to soil fertility, resistant barley varieties and systemic fungicidal disease suppression either by seed treatment or fungicidal sprays. in ethiopia, the disease assessment diagnosis identity of pathogens specific properties measurement amount of disease type of disease future progress likely outcome disease models disease forecasting crop loss yield and quality mashilla east african journal of sciences volume 13 (1) 89-108 100 traditional methods to manage loose smut of barley is use of crop rotation and rogueing smutted ears; but rogueing may not give satisfactory results because the inocula might have already been blown by wind and contaminated the ovaries. hot water treatment at 50 oc for 10 minutes can kill the internal pathogen embedded in the embryo without harming the embryo (zillinsky, 1983), while satisfactory results have also been claimed for cold water and anaerobic treatments (malone and muskett, 1964). anaerobic seed treatment using air-tight storages were also used as physical management (bilgrami and dube, 2001). according to chaube and singh (2001), solar heat treatment effectively controls loose smut of wheat (u. segetum), where the seed is soaked in water for 4 hours on a bright day after which the seed is dried in the sun for 4 hours. they also stated that u. nuda has been effectively subdued by solar heat. in a solar heat treatment of seed on concrete floor, brown paper and mixing seed with sand at 50:50 ratio for different duration (0, 4, 8 and 12 hours) revealed that seeds dried with sand mixture effectively suppressed all six seedborne fungi (alternaria tenuis, asperillus spp., bipolaris sorokiniana, curvularia lunata, fusarium and penicillium spp.) of wheat in 8 and 12 hours solar treatment (khan et al., 2002). on one hand, lack of awareness among the farming communities about the nature of the pathogen and loose smut may make implementation of the abovementioned cultural practices difficult. farmers do not know whether the seed is disease-free or certified. the use of hot water treatment requires skill of measuring the temperature; and they do not also know the value of solar heat treatment. on the other hand, lack of adequate farmland may not allow crop rotation to be practiced in most cases. to minimize such challenges, proper training of farmers on the nature of the pathogen and the disease and cultural management options is advisable. in ethiopia, the role of development agents, district experts, concerned units and officials is immense in alleviating the problem jointly. 6.2. host plant resistance the most economical and environmentally benign way of managing barley loose smut is the use of resistant varieties (menzies et al., 2009; menzies et al., 2010). hence, the choice of resistant varieties is an important component of preventative strategy (zillinsky, 1983). resistant varieties have been developed for areas where barley loose smut is a production constraint (french and schultz, 2009; menzies et al., 2010). barley loose smut is known to be effectively suppressed by the un8 resistance gene isolated by map-based cloning and delimited on chromosome arm 1hl too (zang, 2017). the scholar also reported that sequence analysis identified a un8 candidate gene predicted to be a putative protein kinase with two kinase domains. some barley varieties display a closed flowering habit and so avoid infection as a means of defense even during years of high loose smut infection (rennie and seaton, 1975; jones, 1998). genetic studies have revealed that resistance to u. nuda is generally conferred by single, dominant, independently inherited genes (metcalfe, 1966). however, the incorporation of loose smut resistance genes into new barley varieties can be an arduous procedure because of the time and labor required for testing barley lines for resistance. moreover, none of the recommended barley varieties are completely resistant to all the physiologic races of the three smut fungi, namely u. nuda, u. nigra and u. hordei (dcsunill, 1990). in this connection, it is commendable if reconnaissance surveys are made across the major barley-producing regions of ethiopia to check whether or not physiological races of the pathogen are present. it is well known that several barley varieties are developed based mainly on their high yielding performance, released and are under cultivation in ethiopia (moanr, 2016). however, their genetic resistance potentials against loose smut are not fully evaluated under artificial inoculation with virulent pathogen isolates, implying the need for future researches for their resistance reaction studies as best option for management strategy to sustain barley production and productivity. 6.3. biological control wheat loose smut (u. segetum var.tritici) was suppressed almost completely through seed treatment with any of the bioagents, such as trichoderma viride, t. harzianum; pseudomonas fluorescens and gliocladium virensin combination with the systemic fungicide vitavax@ 0.125% (singh and maheshwari, 2001). these researchers found that values of smut management were even better than full dose of vitavax (0.25%). seed germination percentage in the laboratory, seedling emergence in the field and seed yield per plot were significantly high without any negative effects on the roots or shoots. since the above causal agent is very similar to u. nuda of barley loose smut, the bioagents could be applied against barley loose smut as well. however, in vivo test is required before formulation and mass multiplication of any of the bioagents against loose smut locally. also, there is a need for isolation, identification and characterization of additional indigenous bioagents. furthermore, introduction of exotic bioagents and testing for their efficacies and adaptation for integration with other management options is an attractive issue and could be an effective strategy for future researches in ethiopia. mashilla loose smut (ustilago nuda) of barley (hordeum vulgare) 101 6.4. chemical protection seed treatment with systemic fungicides usually reduces or eliminates the internally seedborne inoculum very effectively, giving 60-100% suppression of the pathogen (neate and mcmullen, 2005; clark and cockerill, 2011; hills, 2018). barley seed treatment by applying systemic fungicides or fungicide mixture, such as carboxin and triadimenol, would help suppress or reduce all the three loose smut levels, if applied properly (french and schultz, 2009). however, u. nuda is not managed by surface-active protectant or contact fungicides used as seed treatment and, to this effect, management depended on hot water or cold water treatments, which killed mycelium in the embryo without killing the embryo, of foundation and certified seed lots until the 1970s (sherwood, 1997). the methods could be still used in areas where systemic fungicide seed treatments are not available or accessible. tisdale et al. (1923) reported for the first time that formaldehyde was as effective as hot water in the suppression of loose smut in six varieties of winter barley. in most parts of the world, correct seed treatment (pickling) with systemic fungicides have been effectively and economically employed against barley loose smut (thomas et al., 2017). the introduction of carboxin as a first systemic seed treatment fungicide is a breakthrough though it is too expensive (menzies, 2008). as treated seed germinates, carboxin moves into the seedling and either kills or stops the growth of the fungus; however, u. nuda isolates that are fully resistant to carboxin have been detected in europe (newcombe and thomas, 1991; sherwood, 1997; menzies, 2008). to avoid the loss of efficacy of systemic fungicide seed treatments, a fungicide rotation scheme in which carboxin seed treatments are used with demethylation inhibitor seed treatments from year to year would be highly recommended (menzies, 2008). similarly, tebuconazole (folicur) has recently been registered for use as a seed treatment fungicide on barley and is very effective in managing loose smut (sherwood, 1997). currently, there are other fungicide-active ingredients that can be used as seed treatments to manage u. nuda on barley and u. tritici on wheat and they are triazole type chemicals, namely difenoconazole, propiconazole, tebuconazole, triadimenol and triticonazole belonging to the ergosterol demethylation inhibitors (menzies, 2008). hewitt (1998) listed the following chemicals as effective systemic fungicides against loose smuts: quintozene (1930), carboxin (1966), oxycarboxin (1966), benomyl (1968), fenfuran (1974), nuarimol (1976), triadimenol (1978), bitertanol (1979), triflumizole (1982), diniconazole (1983), flutriafol (1983), tebuconazole (1986), fenbuconazole (1988), triaconazole (1988) and epoxiconazole (1990). similarly, fuentes-dávilaet al. (2002) presented the following fungicides, including benomyl, carbathiin, carboxin, difenoconazole, etaconazole, ethyltrianol, flutriafol, furmecyclox, myclobutanil, nuarimol and triadimenol as efficacious against loose smut. furthermore, foliar application of a number of broadspectrum systemic fungicides (particularly conazole fungicides) to loose smut-infected plants of wheat and barley in a three-spray program resulted in a marked reduction in the percentage of plants producing infected ears in ireland (figure 3) (jones, 1999). a barley seed treatment experiment was conducted in ethiopia with the objective to examine the effects of four fungicidal seed-dressings (thiram, apron star, dynamic, and propiconazole) and two coating materials (genus coattm and disco ag blue l-237) on loose smut levels (wallelign et al., 2017). the research results revealed that the seed treatment had highly significant effect on days to emergence and flowering, tiller number, grain yield (maximum 1727.8 kg ha-1 with thiram seed treatment and genius plus disco coatings) and smut incidence, where the minimum incidence (0.00%) was recorded from plots sown with seeds treated with propiconazole, while the maximum (15.83%) incidence was recorded from plots sown with untreated barley seeds (wallelign et al., 2017). similarly, the maximum relative efficacies of treatments on the management of loose smut were achieved on plots that received seeds treated with propiconazole for both coated and uncoated seeds (95.81 to 100%), followed by 83.31 and 75.00% for seeds treated with thiram coated with disco plus genius coat and thiram alone, respectively. the minimum (29.19 and 33.31%) efficacy was recorded on plots sown with seeds coated with disco and genius coats, respectively, without fungicide treatment. figure 3. ears of cv. ‘chinese spring’ from plants grown from loose smut-infected seed. from the left: (a) healthy ear; (b) ear from plant sprayed with triadimefon at gs 39 (no signs of infection but lax habit); (c) ear from plant sprayed with triadimefon at gs 39 (partially smutted ear); and (d) completely smutted ear (jones, 1999). a b c d mashilla east african journal of sciences volume 13 (1) 89-108 102 concerning the effects of seed treatment on yield and relative yield losses, wallelign et al. (2017) found that the relative seed yield losses were reduced by all combinations of fungicides with coating materials except propiconazole. the maximum (51.18%) yield loss was obtained from plots sown with seeds treated with propiconazole + disco + genius coats, while the minimum (2.39%) seed yield loss was obtained from plots sown with seeds treated with thiram + disco coat, followed by plots sown with seeds treated with apron star + disco + genius coat, seeds treated with dynamic + disco + genius coat, and seeds treated with apron star alone with corresponding yield losses of 9.02, 8.58 and 9.08% as compared with the untreated check, which had a 21.69% relative yield loss. 6.5. integrated barley loose smut management the use of a single disease control tactic would not bring a desired loose smut management to sustain barley production and productivity. for instance, cultural practices do not completely suppress the disease. similarly, resistant barley varieties may not be available to the growers or more virulent u. nuda strains may appear. also, use of biological control alone may not give satisfactory results and growers may not have the know-how and the bioagnts themselves. on the other hand, application of fungicides as seed treatment or spray has its limitations. hence, under severe infection by loose smut, combination of two, three or more measures based on efficacy, efficiency, environment-friendly and affordability would be necessary (yahyaouiet al., 2003). similarly, wallelignet al. (2015) suggested selecting and employing disease-free barley seeds and screening resistant/tolerant varieties and integrating them together with seed treatments by effective systemic fungicides to manage loose smut and to sustain barley production and productivity. use of disease-free resistant/moderately resistant varieties accompanied by seed treatment with hot water/solar heat and/or systemic fungicides (like carboxin, difenoconazole, propiconazole, tebuconazole, triadimenol or thiram) (davis and jackson, 2017) would give satisfactory results in barley production. singh and maheshwari (2001) also demonstrated in their seed treatment trial that the use of trichoderma viride, t. harzianum; pseudomonas fluorescens and gliocladium virensin integration with the systemic fungicide vitavax@0.125% (carboxin) was effective against smut fungi. 7. discussion since its domestication, barley has been cultivated in the world (african countries, australia, canada, china, european union countries, india, iran, russia, turkey, usa and others), providing food for human consumption, raw materials for industries and animal feed (zhou, 2010). also, it has a long history of cultivation in diverse agro-ecologies, especially in the mid-lands and highlands, and is one of the most important staple cereal crops in the country (eticha et al., 2010). however, the production and productivity of this valuable barley has been constrained by biotic and abiotic factors wherever barley is cultivated. one of the production-limiting biotic factors in ethiopia and elsewhere is barley loose smut caused by the fungus ustilago nuda. sherwood (1997) reported that barley loose smut causes yield losses in excess of 30% on highly susceptible varieties. bekele et al. (1994) previously reported an incidence of 28% for barley loose smut in ethiopia. recently, wallelign et al. (2015) reported grain yield losses of 15 to 25% in the same country in the absence of proper management practices. similarly, tolessa et al. (2015) reported a 20% loose smut severity on major cereal crops (including barley) in borana zone, ethiopia. zang (2017) also reported that barley yield losses of 10 to 30% due to loose smut are still common and encountered in some countries. this variation in yield losses inflicted on barley due to loose smut could be attributed to the initial seed source, freedom from the seedborne pathogen (sanitary measures), percent initial seed infection, seed treatment practices employed, the weather conditions in the agroecologies during flowering, degree of susceptibility/resistance of the varieties used, and seed treatment practices applied before planting. barley loose smut symptoms commonly become evident at the flowering stage and become apparent at heading (asresie et al., 2015; davis and jackson, 2017). barley loose smut may be confused with barley covered smut (ustilago hordei), under field condition because both are seedborne and are similar in their disease cycle (both are systemic pathogens during the vegetative stage), seedling infection processes during seed germination, vegetative growth stage and in the replacement of the spikelets (koch et al., 2013). however, the life cycles of the two pathogens are different in that ustilagohordei is externally seedborne, while ustilago nuda is internally seedborne pathogen (embedded in the embryo). the sori of ustilagohordei remain intact on the rachis and only break during harvesting and threshing contaminating the healthy seed surfaces. unlike barley loose smut, the sori due to ustilagohordei are easily distinguished visually from the healthy seeds if they are not broken during threshing. also, during harvesting by combiner, smoke of teliospores would be released into the sky. on the other hand, the spikelets infected by ustilago nuda would be entirely transformed into a dry, olive brown teliospore masses in the sori (neate and mcmullen, 2005; afanasenko, 2009; johnson, 2014; hills, 2018). the sori due to ustilago nuda are fragile and easily rapture, releasing the teliospores and would be blown to infect open barley flower stigmas and ovules. mashilla loose smut (ustilago nuda) of barley (hordeum vulgare) 103 barley loose smut (ustilago nuda) is a monocyclic disease and the causal pathogen behaves like obligate microorganism. the pathogen attacks cultivated barley and other hordeum species (neate and mcmullen, 2005), including wheat, oats, rye, triticale and many other grasses with the respective forma specialis (menzies, 2008; menzies and gaudet, 2009). unlike non-obligate parasites, ustilago nuda can not be cultivated on culture media to produce colonies. the disease is claimed to be monocyclic because multiple generations can not develop in the same growing season although ovules are infected. of course, the pathogen population can increase over seasons if same infected seeds are sown season after season without change or without seed treatment of any kind. there must be intervention here to provide farmers with disease-free seed of resistant/tolerant varieties and the culture of seed treatment with effective systemic seed treatment fungicides or integrated management options should be developed. similarly, the detection methods, like the embryo count method, for testing the presence or absence of ustilago nuda in the embryos of seed to be planted demand professional inputs or expertise. malone and muskett (1964) previously reported the existence of a number of physiological races of the fungus and presence of high degree of resistance in some host varieties. however, dhitaphichit and jones (1991) reported two physiological races (a virulent, capable of overcoming the recessive resistance gene present in differential variety, and the emergence of fungicide‐tolerant races in ireland and expectation of some more physiologic races in other countries, e.g. seed from france contained carboxin-tolerant race of u. nuda. in ethiopia, the main hosts of the pathogen are barley and wheat. but the physiological races present in the country are not tangibly characterized and development of resistance to systemic seed fungicides is not tested. this requires due attention from plant breeders and plant pathologists to act accordingly on the issues. knowing the preconditions to the establishment and development of any plant disease is decisive to develop apt and viable strategies for its sustainable management options. in this connection, cool and damp/wet weather at flowering time is necessary for heavy infection by ustilago nuda since such weather conditions are known to elongate or extend open flower period. similarly, loose smut is predominant in high rainfall areas, which promote floral or seed infection (asaad et al., 2014). in other words, cool, wet, cloudy weather and moderate temperatures (15 to 22 oc) are known to promote longer and more open flowering for the host, allowing more time for teliospores to land on florets and germinate into floral tissue (sherwood, 1997; johnson, 2014). these set of conditions are familiar in the medium and highland elevations where barley is principally grown in ethiopia. it implies that integrated barley loose smut management options should be applied to minimize the yield losses in these specific agro-ecologies. of course, there must be continuous and appropriate monitoring of the development of the disease from flowering to heading stage over crop seasons to assess the trend of loose smut increase for decision-making. cultural practices that include high quality clean and healthy seed, hot water treatment, irrigation just after planting, crop rotation, optimum isolation distance and rogueing smutted heads as soon as observed are suggested against loose smut (evans, 1999; french and schultz, 2009; wallelign et al., 2015). the major problem here is lack of knowledge on the nature of the pathogen, its transmission and know-how of application of some methods, like hot water treatment, detection technique of the pathogen in the seed and lack of access to healthy seeds. for instance, seed treatment with hot water at 50 oc for 10 minutes is suggested to kill the internal pathogen embedded in the embryo without harming the embryo (zillinsky, 1983). but the local farmers do not have the know-how and facilities for this seed treatment application this requires research calibration, professional efforts and extension services to the farming communities. according to menzies et al. (2009) and menzies et al. (2010), the most economical and environmentally benign way of managing barley loose smut is the use of resistant varieties. here the main challenge to the local farmers is that though a number of barley varieties are released, the reaction of these varieties is not well investigated via artificial inoculation with virulent isolates collected from all over the country. similarly, the physiological races of the pathogen that exist in the country are not tangibly known. after all, the farmers may not have access to the improved varieties and commonly use their own saved seeds that may have carryover embryo-embedded pathogen. all these situations imply that plant breeders, plant pathologists, the extension wing and concerned institutions should work together to provide practical solutions to problems associated with use of resistant varieties. singh and maheshwari (2001) reported that seed treatment with any of the bioagents, including trichoderma viride, t. harzianum; pseudomonas fluorescens and gliocladium virensin combination with the systemic fungicide vitavax@ 0.125% almost completely suppressed wheat loose smut (u. segetum var. tritici), the pathogen that is very similar to usilago nuda. botanicals may be considered in the same category. the question here is the feasibility issue since these bioagents are under investigation, especially in ethiopia the biological control strategy is at an infant stage. isolation and characterization of indigenous bioagents is required; similarly, the adaptability and efficacies of such bioagents should be duly tested and formulation and mashilla east african journal of sciences volume 13 (1) 89-108 104 mass multiplication of the bioagents should be determined ahead of recommendation. several scholars believe that seed treatment with systemic fungicides eliminates the internally seedborne inoculum very effectively, giving 60-100% suppression of the pathogen (neate and mcmullen, 2005; clark and cockerill, 2011; hills, 2018). menzies (2008) reported that difenoconazole, propiconazole, tebuconazole, triadimenol and triticonazole effectively managed loose smut of both barley and wheat. similarly, french and schultz (2009) stated that seed treatment with systemic fungicides, such as carboxin and triadimenol, would generally suppress loose smut levels, if applied properly. however, several other authors (newcombe and thomas, 1991; sherwood, 1997) and menzies (2008) also reported that u. nuda isolates developed full resistance to carboxin in europe. that means, the loose smut causing pathogen becomes insensitive to the systemic fungicide. this implies that there is variability in the pathogen and/or emergence of new physiological race(s) that sharply reduce(s) the efficacy of the seed treatment fungicide. besides, systemic seed treatment fungicides are expensive and use of fungicides is not environment-friendly. not only that, systemic seed treatment fungicides are not easily accessible to the local farmers and farmers may not have the know-how of application of such fungicides. generally, the use of separate disease control tactics would not give satisfactory and sustainable loose smut management. hence, it can be comfortably concluded that use of combination of disease-free seed, hot water seed treatment, employment of resistant/tolerant varieties and seed treatment with effective systemic fungicides prior to sowing would alleviate barley loose smut problem wherever the disease is a pressing constraint. 8. conclusions barley loose smut, which is caused by an internal seedborne fungus ustilago nuda, is one of the major diseases of the crop worldwide. in this piece of work, attempts have been made to review the economic importance of loose smut, biology of the pathogen, ecological requirements for epidemics, and management options for sustainable barley production. barley loose smut could cause crop yield losses of up to 30% or more worldwide. some studies conducted on barley loose smut in ethiopia also estimated similar yield losses, especially on susceptible varieties under favorable environmental conditions to the disease and that lead to epidemics. the newly infected and harvested seed externally looks normal and the food quality is not affected, but is not suitable for planting without seed treatment in the next crop season since the pathogen is embedded in it. there is no single satisfactory method to control barley loose smut worldwide. resistant or tolerant varieties may not be available or may not have durable resistance. it is known that the variability of ustilago nuda and existence of many physiological races or emergence of new races lead to development of resistance to the effective systemic seed treatment fungicides, like carboxin. biological control option is still at an infant stage under research consideration. in ethiopia, smart farmers try to rogue the smutted barley spikes or heads as soon as observed; but the majority of the local farmers use their own saved seeds since they do not have access to systemic seed treatment fungicides and improved seeds. the implication is to use integrated barley loose smut management option that comprises cultural practices, such as disease-free seeds, use of hot water seed treatment, use of seeds of resistant/tolerant varieties, biological control (even botanicals) and systemic seed treatment fungicides. it is known that several barley varieties have been released for cultivation in ethiopia. besides, there are some landraces in the country. in this regard, plant breeders need to test these materials for resistance to loose smut. it is also desirable to collect the physiological race(s) of ustilago nuda and characterize them using the conventional methods and employing molecular techniques. screening systemic seed treatment fungicides and calibrating the doses is recommended for practical purpose. similarly, the use of hot water treatment and/or heating by direct sunlight radiation needs investigation in controlling loose smut. for ethiopian farmers, the best management options are integrating resistant barley varieties with cultural practices, like use of disease-free seed, timely rogueing smutted spikes at flowering, and seed treatment with hot water as well as effective systemic fungicides. overall, research on integrated barley loose smut management is timely for sustainable barley production and productivity in the country. 9. acknowledgements i thank professor nigussie dachassa and dr habtamu terefe for editing and shaping the paper for contributing valuable and constructive criticisms. 10. references abraham tadesse (ed.). 2008. increasing crop production through improved plant protection – volume i. plant protection society of ethiopia (ppse), 19-22 december2006. addis ababa, ethiopia. ppse and eiar, addis ababa, ethiopia. 598 pp. afanasenko, o. s. 2009. ustilago nuda (jensen) kellerm. et swingle loose smut: economic plants and their diseases, pests and weeds. 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and (2) determine the economics of fungicide application in the management of garlic rust. field experiments were conducted in gidan and lalibella districts of north wollo, ethiopia, using three garlic varieties, namely chelenko-1, tseday, and a local cultivar. nativo and tilt fungicides were sprayed with alternate and alone applications during the 2018 cropping season. treatments were arranged factorially in a randomized complete block design with three replications. analyses of variance revealed that interaction effects of nativo, tilt, and their alternate applications with chelenko-1 and tseday varieties showed the lowest disease severity, area under the disease progress curve, and disease progress rate as compared to the unsprayed plots of all varieties. in lalibella, the variety chelenko-1 showed significantly higher (9 t ha-1) yield and, exhibited 28 and 21% yield advantages over tseday variety and the local cultivar, respectively. however, there was no significant difference among the fungicides tested on bulb yield in both districts, but lower relative yield losses were recorded in response to application of nativo and tilt alone. the economic analysis also confirmed that sole application of nativo on local and tilt on both tseday and chelenko-1 showed higher net profit and marginal rates of return than other treatment combinations. thus, the fungicides tilt and nativo alone were relatively effective against garlic rust and economically profitable in lalibela and related agro-ecologies for the variety chelenko-1. however, there was no significant variation in garlic bulb yield of all varieties in gidan, and the same fungicides with local garlic variety can be used for rust management and sustainable garlic production. keywords: audp; bulb yield; dpr; fungicides, nativo; severity, tilt 1. introduction garlic (allium sativum l.) is the second most important allium species next to onion (allium cepa l.). it grows worldwide in all temperate to subtropical and mountainous tropical areas (rabinowitch, 2002). annual production and area coverage of garlic reached 26,573,001t and 1,468,811 ha, respectively, in the world (faostat, 2016). ethiopia, which provides an annual bulb production of 138,664 t, is the 2nd most garlic producer next to egypt in africa and it ranked 13th in the world (faostat, 2016). however, ethiopia accounts for lower production and productivity (9.18 t ha-1) than the world’s average production (csa, 2018). in different parts of ethiopia, production, productivity, and area coverage of the garlic crop are significantly different. in north ethiopia, especially north wollo, garlic is among the major bulb vegetable crops, which is cultivated mostly under irrigation conditions in all small-scale farming practices. annual average production area and garlic productivity in north wollo have been estimated with corresponding 347.82 ha and 6.9 t ha-1, the yield of which is by far less than the national average (9.18 t ha-1) yield (csa, 2018). in spite of its lower productivity from time to time due to numerous biotic threats, the demand behind garlic is very high due to its medicinal value and it is recognized in the treatment of hypertension, diabetes, bacterial and fungal diseases, cancer, rheumatism, ulcer and whooping cough (ahmed et al., 2007). it is among the condiments and flavoring vegetable crops, which have numerous nutritional values. the production of dried and processed garlic products are also used for food preparation and as dietary health-food supplements (diriba, 2016; getu et al., 2017). others, like vegetative propagation of garlic, allows the production of a uniform crop that preserves quality traits, flavor and the nutritive properties of the crop (gebremedhin and abrha, 2015). zemenu et al. east african journal of sciences volume 14 (1) 65-82 66 various biotic and abiotic factors are the major bottleneck constraints for diminishing production and productivity of garlic in different agro-ecologies. among the various challenges, biotic factors are the main contagious and infectious diseases, of which garlic rust (puccinia allii r.), white rot (sclerotium cepivorum b.), pink rot, mosaic virus and nematodes are the most widespread and destructive pathogens of cultivated garlic crops (daniel et al., 2017). garlic rust, that can pose a high epidemic within a short period, is the major constraint in garlic production areas in north wollo and is able to spread a long distance for infection. accumulation of the pathogen causes severe bulb yield reduction due to the high density and even distribution on the host plants (flory and clay, 2013). at higher epidemic level, garlic rust resulted in significant yield penalty in garlic production (cscc, 2007). according to shah et al. (2016), garlic rust is responsible for huge losses under favorable climatic conditions and the disease incidence ranges from 95.0 to 100%, whereas the disease severity can be greater than 65%. in this regard, tadesse (2014) confirmed that 49% of bulb yield loss was due to severe infection of garlic rust. however, management options, such as the use of resistant/tolerant garlic varieties with supplementation of appropriate and compatible fungicides are recommended applicable management strategies for a long period production system of garlic crop (malik et al., 2017). although the application of fungicides alone against garlic rust is a common practice, the use of integrated management to subdue the disease through combination of various garlic varieties along with compatible systemic fungicides is a more effective means than sole fungicide application. therefore, integrated management of garlic rust is the most efficient, environmentally sound and socially acceptable management strategy for sustainable garlic crop production and productivity. so far, management of the disease under irrigation and main rainy season production systems in all smallscale farmers have not been done in lalibella and gidan districts of north wollo, northern ethiopia. hence, finding an effective integrated management tactic for this particular disease is a prerequisite. therefore, the study was carried out with the objectives to (i) evaluate the effects of host resistance, alone and alternate application of the different fungicides on garlic rust epidemic and bulb yield; and (2) determine the economics of fungicide application in the management of garlic rust. 2. materials and methods 2.1. overview of the study areas a field experiment was conducted under irrigation schemes in lalibella zuria and gidan districts of north wollo, amhara national regional state of ethiopia, during the 2018 cropping season. the sites where the experiments were conducted and their respective geographic locations are depicted in figure 1. lalibella and gidan are located on an altitudinal ranges of 20002400 and 2500-2700 meters above sea level (m.a.s.l.), respectively. data obtained from the national meteorological agency, kombolcha branch, indicated that the areas in gidan and lalibella zuria received an average annual rainfall of 800 and 814.9 mm, respectively, with corresponding mean minimum and maximum temperature of 8 and 11 °c and 24 and 27 °c. the districts are mainly variable in their various agro-ecological features: mountainous landscape, groundwater potential, soil type, altitudinal ranges, cropping systems and typical humid/sub-humid weather conditions (national meteorological agency, kombolcha branch, 2018). figure 1. map of the study areas showing field experimental sites in north wollo, ethiopia, during the 2018 cropping season. zemenu et al. management of garlic rust 67 2.2. planting materials and fungicides the experiment was carried out in hot spot areas of farmers’ fields under irrigation conditions during the 2018 cropping season. three garlic varieties, namely chelenko-1 (obtained from haramaya university) and tseday (from debre zeit agricultural research center) and one local control, all of which had different responses to garlic rust, were used as varietal components of the experiment. brief descriptions are presented on the agronomic characteristics of the garlic varieties in table 1. additionally, two commercially available and registered foliar fungicides were used for the experiment at the dose of manufacturers’ recommendations. these fungicides were tilt (propiconazole), nativo 75 wg (water dispersible granule of 250 g kg-1 trifloxystrobin + 500 g kg-1 tebuconazole) and alteration of tilt and nativo 75 wg, which were used alternatively or one after the other and alone. the detail descriptions of fungicides used are presented in table 2. 2.3. treatments, experimental design and management procedures the experiments consisted of 15 treatment combinations (table 3). a plot size of 2.5 m x 1.8 m area, and 0.3 m inter-rows and 0.1 m intra-plants spacing were used during the experiment. plots and blocks were separated by 1.0 m and 1.5 m, respectively. there were five rows of garlic per plot and the plants were spaced at 0.25 m in each row. the central three rows were used as effective rows for data collection. the treatments were arranged in factorial experiment in a randomized complete block design (rcbd) with three replications. planting was made at gidan and lalibella on 03 and 10 september 2018, respectively. applications of fungicides were done at 5:30 p.m. starting from the onset of the first typical symptom of the disease. four times spray frequencies of fungicides were employed at seven-day interval as used by worku (2017). plastic sheets were used to shield from drift problems of fungicides among the plots and between the blocks. garlic cloves were treated with apron star prior to planting to prevent untargeted seedborne disease(s) as this fungicide is good for seed treatment and also effective for white rot disease management as suggested by dilbo et al. (2015). recommended fertilizers, including nps and urea, were applied and urea was used in split applications where half of it was applied at planting and the remaining half was applied at 35 days after planting. irrigation interval was set following farmers’ practices and furrow irrigation method was employed. other agronomic practices, like weeding, earthing up, removal of off-types and regular monitoring were done uniformly to each experimental plot as recommended for the crop in the areas zemenu et al. east african journal of sciences volume 14 (1) 65-82 68 table 1. characteristic features of tested garlic varieties in lalibella zuria and gidan districts of north wollo, ethiopia, during the 2018 cropping season. variety year of release altitudinal range (m.a.s.l.) days to maturity (day) soil type disease reaction yield (t ha-1) maintaining center/institute chelenko-1 2014 2000-2400 132 black moderately susceptible 9.3 haramaya university tseday 1999 1800-2500 133 black moderately susceptible 8.13 debre zeit agricultural research center local material ----susceptible -- table 2. descriptions of fungicides tested for their efficacies on garlic rust intensity in lalibella zuria and gidan districts of north wollo, ethiopia, during the 2018 cropping season. s/n trade name active ingredient nature (mode of action) product formulation product rate (l ha1) amount of diluting water (l ha-1) 1 propiconazole (tilt) triazole systemic, protective and curative emusifiable concentration (ec)/wettable powder (wp) 0.5 l 1000 l 2 nativo 75 wg tebuconazole 50%+ trifloxystrobin 25% systemic broad-spectrum, protective and curative water dispersible granule (wg) 1.0 l 1000 l zemenu et al. management of garlic rust 69 table 3. treatments and respective treatment combinations of fungicides with varieties used in the experiments under irrigation condition in gidan and lalibella zuria districts of north wollo, ethiopia, during 2018 cropping season. s/n varieties fungicides treatment combinations 1 chelenko-1 tilt chelenko-1 + tilt 2 tseday nativo 75 wg chelenko-1 + nativo 3 local tilt + nativo chelenko-1 + tilt + nativo 4 -nativo + tilt chelenko-1 + nativo + tilt 5 -control chelenko-1 control 6 tseday + tilt 7 tseday + nativo 8 tseday + tilt + nativo 9 tseday + nativo + tilt 10 tseday control 11 local + tilt 12 local + nativo 13 local + tilt + nativo 14 local + nativo + tilt 15 local control 2.4. disease assessment garlic rust incidence and severity were assessed in a weekly basis. disease incidence was determined by counting the number of plants that showed visible disease symptoms/signs of the total plants of three central rows per plot. incidence (%) = x 100 disease severity was estimated as the percentage of infected leaf areas from the total leaf areas of sampled plants in the central three rows of garlic plants. it was assessed on 15 randomly pre-tagged plants at the central three rows of each plot. the disease severity was assessed six times using 0-5 scoring scale as suggested by koike et al. (2001); where, 0 = noninfected, 1 = 1 to 10% infected leaves, 2 = 11 to 25% infected leaves, 3 = 26 to 50% infected leaves, 4 = 51 to 75% infected leaves, and 5 =76 to 100% infected leaves from the total areas coverage of each plant. the percentage severity index (psi) was determined from the disease severity data following the procedure suggested by wheeler (1969). psi = sum of numerical ratings total number of plants scored x maximum score on scale x 100 area under disease progress curve (audpc): it was calculated from disease severity data following the formula suggested by campbell and madden (1990): audpc = x𝔦 + x𝔦 + 1 2 𝔦 (t𝔦 + 1 − t𝔦) where, xi is the disease severity at the ith assessment, ti is the time of the ith assessment in days from the first assessment date and n is the total number of disease assessments. thus, audpc summarizes the disease progress data in each treatment and it could be expressed in %-days. 2.5. yield and growth parameters assessment leaf number, leaf length, days to physiological maturity, plant height (cm), stand count at harvest, bulb diameter (mm), number of cloves/bulb, marketable and unmarketable yields (kg) were recorded from harvested plots in the field. description of each parameter entry is presented as follows. leaf number: number of alternative or sideway leaves from the base of the plant to the tip from the three central rows of 15 randomly taken plants per plot were considered and average leaf numbers of 15 sample plants in each plot were used for analysis. plant height (cm): plant height was measured at physiological maturity stage from the harvestable rows of 15 randomly taken plants. mean of 15 measured plants in each plot was used for statistical data analysis. stand count at harvest: number of plants from the three central/harvestable rows per plot was counted at harvest for data analysis. days to physiological maturity (dm): physiological maturity was determined by visual observation of plants in each plot. hence, when the aerial plant parts were ready for harvest, that date was considered as the last date of recording for physiological maturity. bulb weight (g): bulb weight was measured from the harvestable rows of 15 randomly taken plants. individual bulb weight was measured through sensitive balance and average bulb weights of 15 bulbs per plot were used for final data analysis. zemenu et al. east african journal of sciences volume 14 (1) 65-82 70 bulb diameter (mm): bulb diameter was measured from the three central/harvestable rows of 15 sample plants in each plot. after harvesting, each individual bulb diameter was measured via caliper and average bulb diameters from 15 plants were used in each plot for data analysis. cloves per bulb: number of individual cloves was obtained from the harvested three central rows of each plot in individual bulbs of 15 sampled plants. clove numbers were hatched manually and average clove numbers of 15 individual bulbs were used for analysis. total bulb yield (kg): total bulb yield was measured from the middle three rows of each plot. from the three central rows, bulbs were harvested and later converted into tons per hectare (t ha-1). marketable bulb yield (kg): the marketable bulb yield was obtained by deduction of the unmarketable yield from the total bulb yield per plot. unmarketable bulb yield (kg): unmarketable bulbs were separated from the middle harvestable rows and weighed and these included disease-infected bulbs, like white rot, especially in gidan district but since it occurred lately, it was not a serious problem. however, size and underweight were not the issue of unmarketable bulb yield in both locations. 2.6. relative yield loss bulb yield loss is the reduction of crop yield due to garlic rust and it was measured as percentage of yield reduction from unsprayed (unprotected) plots compared with maximum chemical protected plot using the following formula: ryl (%) = y1 − y2 y1 x100 where, ryl = relative yield loss (%), y1 = mean of the respective parameter on maximum protected plot, and y2 = mean of the respective parameter in other treatments and/or unprotected plot. 2.7. data analyses disease incidence, severity, audpc, growth parameters, yield and yield-related components were subjected to analysis of variance (anova) using sas version 9.0 (sas, 2004) following the standard procedures of gomez and gomez (1984). least significant difference (lsd) values were used to separate differences among the treatment means at 5% probability level. relationships of disease severity, audpc, disease progress rate with yield and yieldrelated parameters were examined through pearson correlation analysis. logistic [(y/1-y)] (van der plank, 1963) and gompertz [–ln(-ln(y)] (berger, 1981) epidemiological models were used for the goodness of fit in estimating of disease progression from each treatment. the goodness of fit of the models was determined based on the magnitude of the coefficient of determination (r2) and residuals of standard error (se) (campbell and madden, 1990). the logistic model had higher values of the coefficient of determination (r2) and the lower value of standard error than the gompertz model. thus, the data were better fitted to logistic model and the transformed psi data were regressed over time to determine the regression equation and the slope of the equation, which defines the rate parameter. the regression analysis was done using minitab software (new version 17 for window). the two locations were environmentally different because of heterogeneity of variance as tested by bartlett’s test and results of the ftest for most of the parameters were found highly significantly (gomez and gomez, 1984). thus, the data collected from the two locations were not combined for the analyses. 2.8. partial budget analysis the price of garlic bulb yield per kilogram and total sale from one hectare and price of fungicides were considered for the cost and benefit analysis. the price of garlic bulb (birr kg-1) was obtained from the local market and a total sale from one hectare was computed. the use of additional input cost to earn marginal benefit in the experiment was analyzed using partial and marginal rate of return (mrr) as computed by considering the variable cost available for the respective treatments. the marginal rate of return measures the effect of additional capital invested on net returns using new managements compared with the previous practices (cimmyt, 1988). adjusted yield (adj.y): the adjusted yield was the average yield adjusted downward by 10% to reflect the difference between experimental yield and farmers’ yield. it was determined as adj.y. = av.y – (av.y*0.1); where, av.y = average bulb yield and adj.y = adjusted bulb yield. mrr = ∆ni/∆ic, where, mrr = marginal rate of returns, ∆ni = change in net income compared with control and ∆ic = change in input cost compared with control. 3. results 3.1. onset of garlic rust and its incidence garlic rust first appeared at gidan and lalibella zuria on 08 and 25 november 2018, i.e. 65 and 75 days after planting (dap), respectively. incidence of the disease, that was 100%, was equally distributed in all plants in each plot, and subsequent assessments were performed for six times at seven-day interval and the disease progress was relatively rapid in unsprayed plots. zemenu et al. management of garlic rust 71 3.1.1. effect of garlic varieties, fungicides and their combinations on garlic rust development results obtained from the different garlic varieties/fungicide application alone and in alternation had significant impacts on garlic rust development. even though the resistance level of each garlic variety was lower, garlic rust was highly influenced by the application of tilt and nativo fungicides alone, in combination and in alternation. interaction effects of garlic variety x fungicide indicated that psi at final assessment date, audpc and disease progress rate revealed a significant (p0.05) difference at both locations. 3.1.2. disease severity analysis of variance revealed that there was an interaction effect of variety x fungicide for mean severity of garlic rust at final date of assessment and they showed significant (p0.05) difference in both gidan and lalibella districts. the maximum (95.3%) mean severity was obtained on the untreated plots of the local cultivar, and followed by untreated plots of chelenko-1 and tseday varieties, which exhibited similar results with mean severity of 90.1% at 114 dap at lalibella. but, lower and insignificant mean severity was observed on the other treatments on the last assessment date in the same location at lalibella. regarding gidan, the highest (83.3%) mean garlic rust severity was recorded on the unsprayed plot of the local cultivar, followed by chelenko-1 (75%) and tseday (54.8%) at the last assessment date (104 dap). with the same date of assessment, the lowest mean severity was recorded due to treatment with nativo on plots of chelenko-1 (5.8%) and nativo + tilt treated plots of tseday (5.4%) varieties (table 4). 3.1.4. area under disease progress curve (audpc) the interaction effects of garlic variety x fungicide application on audpc revealed significant (p0.05) difference among the evaluated treatments. the highest (2656.7 %-days) audpc value was recorded from untreated plots of all treatments at lalibella (table 4). untreated plots of tseday and chelenko-1 varieties a non-significant difference; but, the treated tseday variety with tilt differed significantly (p0.05) from nativo and nativo + tilt treated chelenko-1 variety. the treated local cultivar with nativo, tilt and their alternate applications showed a significant (p0.05) difference from the treated chelenko-1 and tseday varieties and this had high audpc value. however, the fungicides nativo, tilt and their alternate applications on the local cultivar revealed nonsignificant (p>0.05) difference among themselves. a similar phenomenon was depicted in gidan on tested garlic varieties as well as the fungicides applied (table 4). table 4. interaction effect of variety x fungicide on garlic rust on final psi and audpc at lalibella zuria and gidan districts of north wollo, ethiopia, during the 2018 cropping season. variety fungicide lalibella a gidan a psi (f) audpc psi(f) audpc chelenko-1 unsprayed 90.1a 2203.3b 75.71a 1718.8a nativo 18.57c 698.3e 5.80c 543.4bc nativo +tilt 16.69c 727.7e 8.95c 648.4bc tilt 18.56c 772.7e 12.14c 681.9bc tilt + nativo 16.66c 833.7e 20.0c 768.8b tseday unsprayed 90.09a 2295b 54.86b 1392.7a nativo 18.09c 636e 6.43c 584.3bc nativo +tilt 19.33c 835e 5.43c 504.7c tilt 19.05c 1038.8d 17.62c 779.0b tilt + nativo 18.19c 743.3e 7.33c 608.9bc local unsprayed 95.3a 2656.7a 83.33a 1754.8a nativo 32.38b 1718.8c 7.14c 547.7bc nativo +tilt 33.81b 1835c 12.98c 802.7b tilt 36.66b 1855c 17.14c 800.4b tilt + nativo 32.86b 1916c 8.52c 573.8bc means 37.00 1384 22.89 802.31 cv (%) 13.4 10.74 53.55 34.92 lsd (0.05) 8.10 246.14 20.44 467.14 note: a psi (f) = final percentage severity index at 114 dap and 104 dap in lalibella and gidan, respectively, audpc = area under disease progress curve. cv = coefficient of variation, lsd = least significant difference at 0.05 level of probability. zemenu et al. east african journal of sciences volume 14 (1) 65-82 72 3.1.5. disease progress rate (dpr) regarding disease progress rate, garlic rust progressed highly when garlic varieties were left untreated as compared to the treated plots at lalibella. the variety chelenko-1 with no-fungicide application revealed a high (0.227 unit day-1) disease progress rate as compared the other two varieties in lalibella (table 5). in addition, a very high (0.3321 unit day-1) disease progress rate was recorded on unsprayed plot of the local cultivar even higher than the rate computed from the untreated plots of the varieties chelenko-1 and tseday at lalibella. however, the integration of varieties with fungicide applications exhibited a significant effect on the disease progress rate (table 5). in spite of lower disease pressure in gidan than in lalibella, the lowest disease progress rate was recorded on the treated chelenko-1, tseday and local cultivar. even negative recording was observed on the fungicides nativo, tilt, nativo + tilt, and tilt + nativo treated garlic varieties because most recordings at the fifth (97 dap) and sixth (104 dap) assessment dates as compared with early assessments were very low due to digressive phase of the disease epidemics (table 5). 3.1.6. disease progress curve (dpc) at lalibella experimental site, the disease progress in untreated control was alarmingly increased from first date of assessment (79 dap) to fifth assessment (107 dap), while it was declined and continued constantly from fifth to last date of assessment (114 dap) (figure 2). similar situations were observed in gidan experimental site, where the disease progress rate increased up to 90 dap and then increased again during 97-104 dap. however, the pattern of disease progress in sprayed treatments was initially accelerated (during 79-86 dap) and then the disease constantly increased up to the fourth assessment date (100 dap) in lalibella district. in the final two assessments, disease progress became slow since first white flecked and small yellowish symptom of rust on the lower leaves became lost and the leaves recovered to normal due to weekly-based fungicide spray zemenu et al. management of garlic rust 73 table 5. disease progress rate (r) and parameter estimates of garlic rust under the different garlic varieties and fungicides applications in lalibella and gidan districts of north wollo, ethiopia, during the 2018 cropping season. variety fungicide lalibella gidan disease progress rate (unit day-1) a se of rate b se of intercept c r2 (%)d disease progress rate (unit day-1) a se of rate b se of intercept c r2 (%)d chelenko-1 unsprayed 0.227 0.259 -10.540 98.7 0.078 0.294 -3.96 89.8 nativo -0.016 0.410 0.160 42.1 -0.015 0.336 0.997 72.8 nativo + tilt -0.026 0.517 0.930 47.5 -0.001 0.212 1.38 93.4 tilt -0.023 0.583 0.540 32.2 -0.005 0.210 0.258 77.6 tilt + nativo -0.025 0.598 1.190 43.3 0.013 0.281 -0.677 17.8 tseday unsprayed 0.211 0.290 -10.370 98.4 0.068 0.198 -4.436 96.3 nativo -0.020 0.503 0.740 41.1 -0.007 0.252 3.316 96.2 nativo + tilt 0.025 0.394 0.372 53.1 -0.006 0.346 3.081 92.6 tilt -0.010 0.687 0.470 17.5 0.011 0.252 -0.473 34.4 tilt + nativo 0.025 0.774 2.220 50.9 -0.005 0.314 1.391 83.9 local unsprayed 0.332 0.897 -13.970 93.0 0.091 0.206 -5.511 97.3 nativo 0.006 0.724 -1.110 6.9 -0.005 0.224 2.415 95.6 nativo + tilt 0.009 0.579 -2.740 49.3 0.012 0.291 -0.060 50.6 tilt 0.013 0.617 -2.250 36.4 0.017 0.214 -0.955 9.3 tilt + nativo 0.011 0.673 -2.640 41.2 0.004 0.184 0.378 87.6 means 0.047 0.430 -2.460 50.110 0.016 0.250 -0.190 73.100 sd (±) 0.111 0.177 5.012 27.070 0.034 0.052 2.647 30.200 note: a disease progress rate obtained from regression line of disease severity against time of disease assessment (days). b standard error of disease progress rate. c standard error of parameter estimates. d coefficient of determination of the logistic epidemiological model zemenu et al. east african journal of sciences volume 14 (1) 65-82 74 figure 2. garlic rust (p. allii) disease progress curves as influenced by alternate and alone application of the different fungicides and garlic varieties in lalibella district, north wollo, ethiopia, during 2018 cropping season. figure 3. garlic rust (p.allii) disease progress curves as influnced by alternate and alone application of fungicides and garlic varieties at gidan district, north wollo, ethiopia, during 2018 cropping season. 3.2. effect of fungicides and garlic varieties on growth, yield and yield-related components in lalibella, interaction effect of garlic variety x fungicide on plant height, maturity date, leaf number, number of cloves per bulb and marketable bulb yield revealed non-significant difference, while the parameters bulb diameter and bulb weight were significantly influenced by the interaction effect (table 6). in gidan district, variety x fungicide did not show any significant interaction effect on all measured parameters (table 7). thus, each individual parameter that did not reveal any interaction effect is presented separately for both locations. 3.2.1. growth parameters results showed significant (p0.05) variation in days to physiological maturity of garlic varieties. the maximum (141.6 days) duration for maturity was recorded on the variety chelenko-1 and it was later in maturing by 20 days than the local garlic variety. tseday variety also exhibited delay in maturity by 15 days from the local one. but all tested unsprayed garlic varieties exhibited shorter days to maturity (127.7 days) than the sprayed 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 100.00 79 86 93 100 107 114 se ve ri ty ( % ) days after planting (dap) unspray nativo nativo+tilt tilt tilt+nativo 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 100.00 69 76 83 90 97 104 se ve ri ty ( % ) days after planting (dap) unspray nativo nativo+tilt tilt tilt+nativo zemenu et al. management of garlic rust 75 treatments and this was significantly (p0.05) different from the treated chelenko-1, tseday and local cultivar. however, there was no statistical difference in days to maturity among the fungicides applied. a similar trend was observed in gidan district in both protected and unsprayed plots of garlic varieties (table 6). similarly, plant height and number of leaves per plant revealed significant (p0.05) differences among the tested garlic varieties in lalibella. but, tseday and the local cultivar were statistically on par with their plant heights. regarding gidan district, there was no significant (p>0.05) difference among garlic varieties on plant height and number of leaves. additionally, insignificant difference was observed among the fungicides nativo, tilt and their alternate applications in both locations. however, statistically different and lower plant height and numbers of leaves were recorded on unsprayed treatments than the sprayed treatments in both lalibella and gidan districts. 3.2.2. yield and yield-related parameters in lalibella, the least (12.1) number of cloves per bulb was recorded on local garlic variety and it was significantly (p0.05) different from both chelenko1(17.7) and tseday (16.8) varieties. however, the two improved garlic varieties produced statistically similar number of cloves per bulb. regarding marketable bulb yield, significant (p0.05) variation was recorded in bulb yield among the evaluated garlic varieties in lalibella. the variety chelenko-1 gave higher yield than the other two varieties, and it was 2 and 2.5 t ha-1 more yield than the local and tseday garlic varieties, respectively, in lalibella. but tseday and local garlic varieties gave similar bulb yields and these were significantly not different from each other in lalibella. the garlic varieties in combination with the fungicides produced comparatively higher bulb yield (8.02 t ha-1) than the unsprayed plots of all garlic varieties (5.3 t ha1) despite the yields obtained in these fungicide applications were not significantly altered in lalibella (table 6). table 6. effects of garlic varieties and fungicides on growth, yield and yield-related components of garlic at lalibella district, north wollo, ethiopia, during the 2018 cropping season. treatment a maturity date (days) plant height (cm) leaf number per plant number of clove per bulb marketable bulb yield (t ha-1) variety chelonko-1 141.6a 56.7a 7.4a 17.7a 9.0a tseday 134.3b 51.4b 6.8b 16.8a 6.5b local 120.2c 48.4b 6.2c 12.1b 7.1b mean 132.0 52.2 6.8 15.5 7.5 lsd (0.05) 3.02 4.05 0.5 1.8 1.6 fungicide nativo 131.6ab 51.8a 7.5ab 16.1ab 8.8a tilt 133.2a 53.7a 6.8b 16.9a 8.0a nativo + tilt 133a 50.8a 7.6a 15.2ab 7.8a tilt + nativo 134.6a 51.6a 7.4ab 15.2ab 7.5a unsprayed 127.7b 52.2a 4.7c 14.2b 5.3b mean 132 52.2 6.8 15.5 7.5 cv (%) 3.1 10.4 11.1 15.7 28.8 lsd (0.05) 3.9 5.2 0.7 2.4 2.1 note: a lsd = least significant difference at 0.05 probability level; and cv = coefficient of variation. in gidan, larger numbers of cloves were obtained on the treatment nativo (17.1) and tilt+nativo (16.4) and significant difference was obtained compared to tilt and the unsprayed treatments. regarding marketable bulb yield, statistically insignificant variation was obtained in the three evaluated garlic varieties. except nativo-sprayed treatments that gave significantly higher bulb yield than tilt-treated and unsprayed plots, the rest unsprayed, tilt, tilt+nativo and vice versa treatments were on par with their marketable bulb yields (table 7). zemenu et al. east african journal of sciences volume 14 (1) 65-82 76 table 7. effect of different varieties and fungicides on growth, yield and yield related components of garlic at gidan district, north wollo, ethiopia, during the 2018 cropping season. treatment 1 growth and yield parameter 2 md ph(cm) lnpp bw (g) bd(mm) nc mby (t ha-1) unmby(t ha-1) variety chelonko-1 157.1a 60.1a 6.5a 42.1a 43.6b 15.3ab 5.2a 0.04a tseday 155.3b 60.5a 6.6a 44.3a 44.8ab 16.6a 5.0a 0.05a local 157.4a 58.1a 6.3a 46.3a 46.1a 14.1b 5.1a 0.05a mean 156.6 59.6 6.5 44.2 44.8 15.3 5.1 0.04 lsd (0.05) 0.7 2.9 0.4 4.2 1.8 1.3 1.5 0.02 fungicide nativo 157.4a 60.8a 7.3a 50.1a 46.2a 17.1a 7.2a 0.05a tilt 157.5a 59.5a 6.5b 43.2b 44.1ab 14.6c 5.4ab 0.05a nativo + tilt 157.6a 60.7a 6.7b 47.2ab 46.1a 14.8bc 5.3ab 0.04a tilt + nativo 157a 61.6a 6.3b 43.6b 45.3a 16.4ab 4.4b 0.06a unsprayed 153b 55.2b 5.6c 37.2c 42.5b 13.9c 3.6b 0.06a mean 156.6 59.6 6.5 44.3 44.8 15.4 5.2 0.05 cv (%) 0.60 6.5 8.6 12.9 5.6 11.4 38.7 63.8 lsd (0.05) 0.9 3.7 0.5 5.5 2.4 1.6 1.9 0.03 note: 1 lsd = least significant difference and cv = coefficient of variation. 2 md = maturity date, ph = plant height (cm), lnpp = leaf number per plant, bw = bulb weight (g), bd = bulb diameter (mm), nc = number of cloves, mby = marketable bulb yield (t ha-1); and unmby = unmarketable bulb yield (t ha-1). in lalibella, the average bulb diameter was significantly influenced by the interaction effect of garlic variety x fungicide (table 8). the highest (47.8 mm) mean bulb diameter was recorded on chelenko-1 and local garlic varieties with nativo fungicide application and this was significantly (p0.05) different from the unsprayed plot. also, nativo, nativo+tilt or tilt+nativo on the treated plot of tseday variety was significantly lower in its bulb diameter than the maximum bulb diameter. similarly, interaction effect of variety x fungicide application showed significant (p0.05) variation for the treatment of chelenko-1 variety in combination with nativo, tilt, nativo+tilt and tilt+nativo fungicides applications on bulb weight in comparison of unsprayed plot of chelenko-1 variety (table 8). unlike lalibella, no significant interaction effect was observed on the mean bulb weight and bulb diameter in gidan. but higher bulb weight was recorded on the garlic varieties sprayed with nativo (50.1 g) and nativo+tilt (47.2 g) and these were significantly (p0.05) different from the unsprayed plots of all garlic varieties that exhibited lower (37.2 g) bulb weight (table 8). table 8. interaction effects of garlic variety x fungicide on bulb diameter and weight of garlic in lalibella district, north wollo, ethiopia, during the 2018 cropping season. variety 1 fungicide bulb diameter (mm) bulb weight (g) chelenko-1 unsprayed 32.6e 22.5f nativo 47.8a 56.0ab nativo +tilt 44.6 a-c 54.3a-d tilt 47.6a 54.4 a-c tilt + nativo 46.3ab 60.2a tseday unsprayed 37.1de 29.6ef nativo 38.4de 35.1d-f nativo + tilt 40.8 b-d 40.8b-f tilt 43.1a-d 44.8a-e tilt + nativo 40.8 b-d 40.7b-f local unsprayed 39.4cd 36.4c-f nativo 47.8a 56.2ab nativo + tilt 45.4a-c 45.6a-e tilt 43.2a-d 44.0a-e tilt + nativo 40.1 b-d 39.1b-f mean 42.35 43.8 lsd (0.05) 6.25 19.3 cv (%) 8.86 26.5 note: 1 cv = coefficient of variation; and lsd = least significant difference at 0.05 probability level. zemenu et al management of garlic rust 77 3.2.3. association of disease parameters with growth, yield and yield-components of garlic association of disease progress rate and area under disease progress curve with growth, bulb yield and yield parameters were evaluated using correlation analysis. the area under disease progress curve was highly and negatively associated with all recorded growth, yield and yield-contributing parameters. moreover, yield and area under disease progress curve were highly negatively and significantly (p0.001) correlated (r = 0.46**) to each other in lalibella. on the other hand, disease progress rate was highly and negatively associated with the bulb yield (r = -0.43**) and the most yield contributing parameters, bulb weight (r = -0.48**) and bulb diameters (r = -0.54**) in lalibella (table 9). regarding gidan, audpc and disease progress rate were highly negatively and significantly (p0.001) associated with growth, yield and yield-components. however, unmarketable bulb yield was not significantly (p>0.05) important with other yield parameters despite it was correlated negatively. the disease parameters, such as audpc with disease progress rate, were highly positively and significantly (p 0.001) correlated (r = 0.91**) in gidan (table 10). table 9. coefficient of correlation (r) between growth and yield and disease parameters in garlic in lalibella district, north wollo, ethiopia, during the 2018 cropping season. parameter a md ph bd bw nc mby audpc dpr md 1.000 ph 0.543** 1.000 bd 0.1192 0.404* 1.000 bw 0.2164 0.504** 0.903** 1.000 nc 0.706** 0.542** 0.355* 0.504** 1.000 tby 0.2336 0.548** 0.797** 0.882** 0.494** 1.000 audpc -0.706** -0.2620 -0.406* -0.439* -0.556* -0.46** 1.000 dpr -0.382** -0.0914 -0.54** -0.48** -0.302* -0.43** 0.758** 1.000 note: a md = days to maturity (days), ph = plant height (cm), bd = bulb diameters (mm), bw = bulb weight (g), nc = number of cloves per bulb, mby = bulb yield (t ha-1), audpc = area under disease progress curve (%-days) and dpr = disease progress rate (unit day-1). * = significant at 0.05 and ** = highly significant at 0.001 probability level. table 10. coefficient of correlation (r) between growth and yield and disease parameters in garlic in gidan district, north wollo, ethiopia, during the 2018 cropping season. parameter a md ph bd bw nc mby unby audpc dpr md 1.000 ph 0.205 1.000 bd 0.219 0.117 1.000 bw 0.304* 0.274 0.83** 1.000 nc 0.036 0.124 0.203 0.281* 1.000 mby 0.285 0.385* 0.412* 0.63** 0.312* 1.000 unmby -0.147 -0.264 -0.136 -0.138 -0.031 -0.317 1.000 audpc -0.646** -0.54** -0.373* -0.470* -0.259 -0.391 0.116 1.000 dpr -0.647** -0.47** -0.223 -0.373* -0.318* -0.393* 0.027 0.91** 1.000 note: a md = days to maturity (days), ph = plant height (cm), bd = bulb diameters (mm), bw = bulb weight (g), nc = number of cloves per bulb, mby = marketable bulb yield (t ha-1), audpc = area under disease progress curve (%-days) and dpr = disease progress rate (unit day-1). * = significant at 0.05 and ** = highly significant at 0.001 probability level. 3.2.4. relative yield loss assessment yield losses were computed relative to the average yield of plots with maximum protection against the disease, i.e. the plots treated with nativo alone fungicide applications of garlic varieties in both locations. among the sprayed treatments, nativo alone fungicide applications gave nil/minimum bulb yield losses. relatively, the lower bulb yield losses were also obtained from plots sprayed with tilt alone on tseday and chelenko-1garlic varieties in both locations (table 11). however, total bulb yield losses were reduced by the application of alternate and alone fungicide application compared to the unsprayed check plots. the highest (50.5%) relative bulb yield loss was obtained from unsprayed local cultivar that was higher by 5.1 and 11.9% from unsprayed chelenko-1 and zemenu et al. east african journal of sciences volume 14 (1) 65-82 78 tseday garlic varieties, respectively, in lalibella zuria district. similarly, maximum relative yield losses were calculated for the untreated chelenko-1 (64.68%), local (63.99%) and tseday (63.71%) garlic varieties in gidan district. table 11. relative yield loss of garlic due to garlic rust (p. allii) as influenced by garlic variety and fungicide application in lalibella and gidan districts, north wollo, ethiopia, during the 2018 cropping season. variety fungicide lalibella a gidan a y (t ha-1) ryl (%) rya (%) y (t ha-1) ryl (%) rya (%) chelenko-1 nativo 10.56 0.00 82.70 7.22 0.00 183.14 tilt + nativo 9.78 7.38 69.20 4.33 40.03 69.80 tilt 9.44 10.66 63.32 6.78 6.09 165.88 nativo + tilt 9.44 10.66 63.32 6.48 10.66 152.94 unsprayed 5.78 45.43 0.00 2.55 64.68 0.00 tseday nativo 7.83 6.01 53.23 7.11 0.00 175.56 tilt + nativo 7.34 11.88 43.64 4.44 37.55 72.09 tilt 8.33 0.00 63.01 5.44 23.49 110.85 nativo + tilt 6.56 21.24 28.38 4.78 32.77 85.27 unsprayed 5.11 38.65 0.00 2.58 63.71 0.00 local nativo 10.56 0.00 102.30 8.33 0.00 177.67 tilt + nativo 5.67 46.30 8.62 4.44 46.70 48.00 tilt 6.44 39.01 23.37 5.11 38.66 70.33 nativo + tilt 7.67 27.36 46.93 4.89 41.30 63.00 unsprayed 5.22 50.56 0.00 3.00 63.99 0.00 note: a y = bulb yield (t ha-1), ryl = relative yield loss in percentage and rya = relative yield advantage in percentage. 3.2.5. cost and benefit analysis the partial budget analysis was performed using net returns and marketable bulb yield was considered to compute the marginal rate of return (mrr). a significant variation was observed in net profit among the garlic varieties as well as the fungicides evaluated. the maximum marginal rate of return was obtained on the garlic varieties chelenko-1 and tseday in combination with tilt fungicide alone and local cultivar with nativo alone. in case of alternate fungicide applications, higher marginal rate of return was noted than on unprotected plots. especially treatment of chelenko-1 and local cultivar with nativo+tilt indicated higher marginal rate of return value than tilt+nativo and unsprayed plots (table 12). table 12. partial budget analysis for the garlic rust management through host resistance, and alone and alternate applications of fungicides in lalibella and gidan districts, north wollo, ethiopia, during the 2018 cropping season. variety fungicide adjusted yield (t ha-1) sale price (etb kg-1) sale revenue (etb) total input cost (etb) net profit (etb) marginal rate of return (%) chelenko nativo 8.001 40 320040 1680 318360 100.25 tilt + nativo 6.3495 40 253980 1240 252740 82.90 tilt 7.299 40 291960 800 291160 176.525 nativo + tilt 7.1505 40 286020 1240 284780 108.74 unsprayed 3.7485 40 149940 0 149940 0.00 tseday nativo 6.723 40 268920 1680 267240 76.675 tilt + nativo 5.301 40 212040 1240 210800 58.37 tilt 6.1965 40 227860 800 247060 135.8 nativo + tilt 5.103 40 204120 1240 202880 51.98 unsprayed 3.4605 40 138420 0 138420 0.00 local nativo 8.5005 40 340020 1680 338340 113.32 tilt + nativo 4.5495 40 181980 1240 180740 26.43 tilt 5.1975 40 207900 800 207100 73.925 nativo + tilt 5.652 40 226080 1240 224840 62.00 unsprayed 3.699 40 147960 0 147960 0.00 note: mean unit of mean price of bulb per kilogram was $1.43 (at the current exchange rate of 1$ = 27.94 etb) at the time of produce selling in 2018/19 cropping season. zemenu et al management of garlic rust 79 4. discussion the analysis of variance revealed that the fungicides applied on the different garlic varieties showed significant interaction effect that resulted in the lowest final severity of garlic rust in both lalibella and gidan districts. the fungicide-treated chelenko-1 and tseday varieties manifested very low final severity, which was less by 15% than the protected local cultivar. the low disease severity might be attributed to the fungicides nativo and tilt alone, which are the most effective systemic fungicides that interfere with and inhibit the growth and reproduction of the fungus. in this regard, the variety chelenko-1 and tseday might have a better response/resistance level to rust disease than the local cultivar. bezu et al. (2014) stated that chelenko-1 and tseday garlic varieties revealed moderately susceptible to garlic rust in ethiopia. however, the highest final severity of garlic rust was recorded from the plots of untreated local and both improved garlic varieties, which had a significant impact on bulb yield and yield-related components in both districts. the highest garlic rust severity in the untreated plots was attributed to undisturbed and continuous uredospore germination in that specific host ranges. this current finding is in agreement with the observation of worku (2017) who reported that high (83%) garlic rust severity had been recorded in the untreated garlic crop in ethiopia. interaction effect of garlic variety x fungicide significantly reduced the audpc values at both experimental locations. the maximum audpc value was recorded from the untreated local garlic variety, followed by tseday and chelenko-1 varieties in that order. this might have weakened and disfavored the disease progress by weekly fungicide sprays; consequently, the initial white flecked to small-yellowish disease symptoms became slightly normal and recovered at the end of disease assessment periods. tadesse (2014) also confirmed that garlic rust epidemics were serious and higher on the untreated garlic crops than protected crops, and this revealed high audpc (2080%-days) value in ethiopia. integration of different garlic varieties and fungicide sprays lowered disease progress rates at both experimental sites. the highest disease progress rates were recorded due to heavy infection by garlic rust on all unprotected garlic varieties, while the garlic varieties treated with nativo, tilt and their alternate sprays resulted in minimum disease progress rates during the study. thus, the fungicides nativo and tilt exhibited adverse and antagonistic effects on garlic rust physiology since they suppressed and prohibited further lesion expansions. similarly, application of systemic fungicides consisting of tebuconazole and triazole active ingredients significantly reduces garlic rust and manages 100%, if the spray operation starts on the first onset or disease appearance (gianessi and reigner, 2005; negash et al., 2019). other investigators also stated that epidemics and disease progress rate of garlic rust were highly inhibited due to proper and timely application of tilt and nativo fungicides in ethiopia (tadesse, 2014; worku, 2017). the disease progress curve was another descriptor of rust epidemics at both testing locations. a significant increase in rust epidemics resulted in unsprayed plots of all garlic varieties. however, the disease progress curves in the treated plots were almost constant and declined in the last two-assessment periods, especially in lalibella. thus, it was considered that constant and slow disease progress might be due to inhibition of epidemics and the digressive phase of the disease, which resulted in recovering and normal leaves in the treated-plots of all garlic varieties as compared to untreated plots in all assessment periods. these current findings also agree with the investigation of kassaw et al. (2018) in eastern amhara, ethiopia. negash et al. (2019) also reported in his findings from study undertaken in ethiopia that garlic rust progress was enhanced in untreated-plots, while the curves in the treated-plots declined and negatively skewed. regarding yield components, significant variation in days to physiological maturity was obtained among garlic varieties and in different fungicide applications in both locations. it was recorded that the local garlic variety matured earlier than the varieties chelenko-1 and tseday in lalibella. this might be due to the genetic nature of earliness of the variety and susceptibility to the garlic rust. that is why the most susceptible garlic variety enhanced to set bulbs early and to reach its physiological maturity to escape the disease. the current results also indicated that unsprayed plots of all garlic varieties were forced to maturity early since photosynthetic efficiency in infected leaves was reduced and this phenomenon, in turn, resulted in drying of leaves prematurely. contrarily, the physiological maturity was extended in sprayed plots of all garlic varieties because the treated plants with fungicide remained green for a relatively longer time than the untreated plots; similarly, the undisturbed normal physiological activities might have resulted in increased garlic bulb yield. negash et al. (2019) also found that fungicide-treated garlic plants were delayed in their days to physiological maturity, while untreated ones were obliged to mature early in ethiopia. concerning bulb weight and diameter, an interaction effect was observed among varieties and fungicide applications in lalibella but not in gidan. high mean difference in bulb weight was observed between the most protected and unprotected plots of the variety chelenko-1, implying that integration of variety with fungicide application inhibited maximum progression of garlic rust. on the other hand, garlic rust showed a significant negative impact on bulb weight reduction in unsprayed plots of all tested garlic varieties. the current investigation is in congruent with the finding of mengesha et al. (2015) who reported that severe infection of garlic rust has high bulb penalty. likewise, zemenu et al. east african journal of sciences volume 14 (1) 65-82 80 the protected chelenko-1, tseday and local garlic varieties due to spray with nativo, tilt and their alternate applications showed acceptable and maximum mean bulb diameter. this situation was due to the low and closely nil garlic rust severity in the fungicide-treated plots. previously, kassaw et al. (2018) also confirmed that protected garlic plots with fungicides inhibited rust epidemics and increased yield contributing parameters, such as bulb diameters and bulb weights, in ethiopia. the main effect of garlic varieties and fungicide applications showed a significant difference in marketable bulb yield, while their interaction effect revealed a non-significant difference. an average (9 t ha1) bulb yield of chelenko-1 was significantly higher than the remaining garlic varieties. this could be accounted for its innate genetic potential being recently improved and have also best field performance during the field experiment with respect to plant height, number of leaves per plant, number of cloves per bulb, bulb weights and diameters, especially in lalibella district. reasonable garlic bulb yield was obtained on all the treated-plots since the alternate and alone fungicide applications could enhance growth parameters and suppressed disease progression at both testing locations. this is in line with the finding of worku (2017) who stated that the application of systemic fungicides could suppress further uredospore proliferation, uredia expansion and enhance bulb yield in ethiopia. on the other hand, marketable bulb yield of garlic was highly penalized in unprotected-plots of all garlic varieties. this might be attributed to weighty infection and the contagious nature of the pathogen in unprotected check plots. association of growth, yield and-related components with disease parameters revealed highly significant and negatively correlated at both experimental locations, implying that the observed level of the disease caused a considerable and adverse effects on bulb yield and yield contributing parameters on untreated plots. this current finding is in conformity with the observation of kassaw et al. (2018) and mengesha et al. (2015) who reported the negative relationship between garlic rust parameters with yield and yield-related components that, in turn, exhibited limited garlic bulb production. the partial budget analysis also confirmed that application of nativo and tilt fungicides alone were the most cost effective and efficient towards garlic rust management option. comparatively, maximum net benefit and marginal rate of return resulted from tilt and nativo fungicide applications in comparison with all other alternate and control fungicide applications in both districts. hence, solely application of tilt and nativo for the management of garlic rust on the moderately resistant and susceptible varieties was the relatively more profitable and economically acceptable fungicides than other treatments. 5. conclusions results revealed that maximum, i.e. 83 and 95.3%, severity indexes were observed when the garlic varieties were left unsprayed in gidan and lalibella, respectively. however, comparatively lower disease severity resulted from separate tilt and nativo alone fungicide applications in the two districts. on the other hand, the highest audpc and disease progress rates were calculated for unprotected plots for all garlic varieties under crosswise assessment. consequently, greater bulb yield and yield-component reductions occurred in unprotected garlic crops due to garlic rust. however, the present investigation on three garlic varieties in integration with two kinds of fungicides provided the most important management options to fight against garlic rust. thus, it was found that tilt and nativo fungicides were the most efficient and effective fungicides against garlic rust and these fungicides had the ability to suppress and inhibit rust epidemics at both experimental locations. the partial budget analysis also showed that treatment with tilt alone accompanied by nativo fungicide was the most economically efficient and effective management strategy against garlic rust. lower total variable cost and higher net benefit were also obtained in all garlic varieties when sprayed with tilt and nativo fungicide alone. therefore, from the results of the present study, the application of tilt and nativo fungicide alone with improved chelenko-1 garlic variety for the management of garlic rust was advisable and economically profitable in lalibella and related agro-ecologies. however, since there was no significant variation in the bulb yield of all garlic varieties in gidan district, the same fungicides in combination with local cultivar were found promising for garlic rust management in this specific area. additional management strategies against garlic rust should be studied through host resistance integrated with cultural and agronomic practices, and cost-effective fungicides to provide alternatives for managing garlic rust and sustainable production and productivity. 6. acknowledgements the authors thank sekota dryland agricultural research center (sdarc) for financing 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