Agricultural and Food Science, vol 20(2011) s. 228-234 A G R I C U L T U R A L A N D F O O D S C I E N C E A G R I C U L T U R A L A N D F O O D S C I E N C E Rajala, A. et al. Seed quality effects in barley 229228 © Agricultural and Food Science Manuscript received November 2010 Seed quality effects on seedling emergence, plant stand establishment and grain yield in two-row barley Ari Rajala*1, Markku Niskanen1, Mika Isolahti2 and Pirjo Peltonen-Sainio1 1MTT Agrifood Research Finland, Plant Production Research, FI-31600 Jokioinen, Finland 2Boreal Plant Breeding Ltd. FI-31600 Jokioinen, Finland *e-mail: ari.rajala@mtt.fi Seed viability and vigour play important roles in seedling emergence, plant stand establishment and yield potential. The majority of cereal fields in Finland are typically sown with farm saved seed (FSS). If the quality of the seed is not known, there can be insidious yield reduction. This research was conducted to study the effects of seed quality on seedling emergence rate, seedling number and yielding capacity. The study comprised three-year field experiments conducted during 2007–2009, established at three sites: Jokioinen, Nousiainen and Ylistaro. Spring barley cultivars Saana (2007) and Annabell (2008-2009) were sown at rate of 500 germinating seeds m-2. Five seed lots were included as treatments: farm saved seed (FSS); down- graded seed <2.5 mm (FSS<2.5 mm); upgraded seed >2.7 mm (FSS>2.7 mm); upgraded seed >2.7 mm with disinfection (FSS>2.7 mm + dis); and commercial certified seed with disinfection (CCS). Up- and down-graded seed lots (FSS<2.5 mm, FSS>2.7 mm, and FSS>2.7 mm + dis) all originated from the FSS. Seedling emergence rate was meas- ured from the time when coleoptiles started to break through the soil surface. The number of seedlings (3 × 1 m row per plot) was recorded at five-day intervals four times from the same rows. Plots were harvested at physiological maturity and grain yield (kg ha-1), hectolitre weight (HLW, kg) single grain weight (SGW, mg) and grain protein content (%) were recorded. Seed lots of CCS and FSS>2.7 mm + dis enhanced seedling emergence rate and increased the number of plants compared with other treatments. These two seed lots also produced the highest grain yield and had the lowest grain protein. Seed quality had an apparent effect on plant stand establishment and grain yield. A seed lot effect was evident despite identical targeted sowing rates that took into account germination rate and seed weight. Therefore, differences in seedling emergence and yielding capacity were likely outcomes of variation in seed vigour among the five treatments. Key-words: barley, emergence, plant stand, seed quality, yield Vol. 20(2011): 228–234. A G R I C U L T U R A L A N D F O O D S C I E N C E Rajala, A. et al. Seed quality effects in barley Vol. 20(2011): 228–234. 229228 Introduction Seed viability and vigour determine how success- fully seedlings emerge, plant stand is established and yield potential is built up. Seed viability gener- ally refers to germination rate whereas seed vigour represents the capacity of the seed to develop and produce a normal seedling under various growing conditions. These two traits are affected by several factors, starting from grain-filling period and con- tinuing throughout harvest and storage conditions. Seed age, moisture content, infection by seed-borne pathogens and seed weight are among the charac- teristics associated with seed viability and vigour (Doling 1968, Ching et al. 1977, Khah et al. 1989, Gan et al. 1992, Chastain et al. 1995, Grilli et al. 1995, Reddy et al. 1999, Nonogaki et al. 2010). Dif- ferences between germination rates in the laboratory and seedling emergence rates in the field may vary considerably: seed lots with a germination rate of 85–100% produced seedlings at rates of 47 to 93% according to Steiner et al. (1989). This difference between germination rate and emerged seedling number was attributed to differences in seed vigour under varying conditions (Steiner et al. 1989). Ac- cordingly, seed performance is a consequence of an interaction between seed vigour and prevailing conditions such as sowing depth, soil characteristics, soil moisture and temperature. The shoot apex initially produces the leaf and tiller primordia and after a transitional phase, the spikelet and floral organs (Bonnett 1961; Wadding- ton et al. 1983). Thus, yield formation actually be- gins already at seedling emergence. During a short intensive growing season, as prevails in northern Europe, cereal growth and development are rapid due to the long days. This secures successful crop production in just 80 to 110 days (Peltonen-Sainio and Rajala 2007; Peltonen-Sainio et al. 2009a). Ac- celerated development rate reduces a plant’s poten- tial to compensate for potential setbacks occurring during emergence and early plant stand formation (Peltonen-Sainio et al. 2009a). This emphasizes the central role of seed quality and successful sowing to facilitate even and adequately dense seedling emergence. Successful seedling emergence sets the foundation for the formation of full (= adequately dense) plant stands that utilise available water and radiation efficiently from the start of the intensive growing period (Peltonen-Sainio et al. 2003; Pel- tonen-Sainio et al. 2009a). Depending on a farmer’s preferences, either FSS or CCS are used to sow a crop. Unlike in other European countries, in Finland most cereal fields are typically sown with FSS (Peltonen-Sainio et al. 2003). The proportion of FSS varies among ce- real species and years, ranging from 63% to 80% (Fig. 1). The quality control for FSS depends on the farmer running the required tests. For the certified Fig. 1. The certified seed percent- age (%) in spring cereal sowings. Source: Nordman (2010). 0 5 10 15 20 25 30 35 40 Barley Oats Wheat % 2007 2008 2009 Vol. 20(2011): 228–234. A G R I C U L T U R A L A N D F O O D S C I E N C E A G R I C U L T U R A L A N D F O O D S C I E N C E Rajala, A. et al. Seed quality effects in barley 231230 seed sector, the seed quality is regulated by em- ploying a threshold value for seed germination and other seed quality requirements, which are set by legislative authorities (http://www.evira.fi). Com- pared with viability (=germination rate), seed vig- our is more laborious to measure and define and it is not included in regular seed testing and approval programmes. However, seed vigour may strongly affect seedling emergence rate, plant stand estab- lishment and yield performance, especially under less favourable growing conditions (Steiner et al. 1989, López-Castaňeda et al. 1996). This research was conducted to study the potential differences in seedling emergence rate, seedling number and yielding capacity of seed lots with similar germina- tion rates but varying in other quality traits. Special interest was to reveal potential differences in yield- ing capacity and ranking of seed lots when grown in varying growing conditions. Material and methods This study comprised three-year field experiments conducted during 2007–2009 established at three sites: Jokioinen (60° 48′ 3 N, 23° 28′ 5 E), Nou- siainen (60° 35′ 6 N, 22° 50′ 0 E) and Ylistaro (62° 56′ 3 N, 22° 31′ 0 E). Spring barley cultivars Saana (2007) and Annabell (2008–2009) were sown at 500 germinating seeds m-2. Sowing rate was calculated using following equation kg ha-1= aimed density (plants m -2) × thousand grain weight (g) ______________________________________ germination rate (%) Thus all plots were sown with an identical number of viable seeds (500 seeds m-2) and thereby the potential seed lot effect on growth was not a consequence of different germination rates. Plot size was 6 m2 in Jokioinen and Nousiainen and 10 m2 in Ylistaro. Plots were fertilized with NPK- (23-3-6) fertilizer at 80 kg N ha-1. Weeds were controlled using MCPA, clopyralid, fluorox- ypry –compounds (trademark Ariane S). Five seed lots (treatments) were compared: FSS; FSS<2.5 mm; FSS>2.7 mm; FSS>2.7 mm + dis (disinfection by using triconazole and imazalil -compounds, trademark Robust); and CCS. FSS<2.5 mm, FSS>2.7 mm, and FSS>2.7 mm + dis originated from the same FSS mate- rial, which was produced by applying good farm management practices. Seed lot FSS<2.5 mm consist- ed of seeds passed through a 2.5 mm sieve plate, whereas for the FSS>2.7 mm, and FSS>2.7 mm + dis lots the seeds remaining on the 2.7 mm sieve plate were used. Germination rate and single grain weight of seed lots are shown in Table 1. Seedling emergence rate was assessed at the Jokioinen site (2008–2009) when coleoptiles began to emerge through the soil surface. At first count- ing, three rows per plot were marked (length 1 m). Number of seedlings was counted at five-day intervals four times at the same marked seeding rows. At physiological maturity, plots were har- vested and grain yield (kg ha-1 at 15% moisture content) hectolitre weight (HLW, kg) and single grain weight (SGW, mg) were measured. Grain N concentration was measured with a NIR analyzer (Foss InfraXact). Trial set-up was a randomised block design with four replicates. All statistical analyses were carried out with PASW Statistics 18.0 software us- ing the MIXED procedure (Littell et al., 1996). In the model, seed lot, trial site and year were consid- ered to be fixed effects, while blocks nested within trial and year were considered to be random when computing means for grain yield and yield qual- ity parameters. By considering seed lot, trial site and year as a fixed effect, the model was more ap- propriate to reveal potential seed lot by growing condition interaction, i.e. seed lot differences in yielding capacity when grown in varying growing conditions (site and year). Comparisons of treat- ments were done using the Bonferroni test. Seed lot was considered to be a fixed effect, while year and block were considered to be random when computing means for seedling numbers of cv Annabell for trials carried out at Jokioinen. A G R I C U L T U R A L A N D F O O D S C I E N C E Rajala, A. et al. Seed quality effects in barley Vol. 20(2011): 228–234. 231230 Results and discussion CCS and FSS>2.7 mm + dis seed lots enhanced seedling emergence rate and increased the number of plants compared with the other seed lots at trials carried out in Jokioinen (Fig. 2). Improved emergence was evident despite similar numbers of germinat- ing seeds per m2. Apparently, seed treatment with fungicide improved seed’s potential to produce live and vigour seedlings to emerge through the soil. Similar response has been reported in an extensive Swedish study carried out on several locations and years (Johnsson et al. 1998). Under field condi- tions, also seed vigour is known to affect seedling emergence (Khah et al. 1989, Steiner et al. 1989, López-Castaňeda et al. 1996). Post-sowing drought periods occur regularly in the main cereal produc- tion areas of Finland (Pajula and Triipponen 2003, Peltonen-Sainio et al. 2010). Sparse precipitation in conjunction with heavy soils (typically clay in southern Finland) set high requirements to seed vig- our (Peltonen-Sainio et al. 2009a, Peltonen-Sainio et al. 2010). Hence, actual seedling number may differ markedly from potential seedling emergence based solely on germination rate (Fig. 2). This was evident in this study as the number of emerged seedlings did not reach the target 500 seedlings m-2 for any of the seed lots. The range of emerged seedlings was from 68% to 86%, which is comparable with the values presented by Steiner et al. (1989). Barley has the highest tillering capacity of the cereal species grown in northern growing conditions (Peltonen- Sainio et al. 2009b). Despite of this, sparse and/ or uneven seedling emergence may result in yield reductions in a short and intensive growing period (Peltonen-Sainio et al. 2009a,b). Seed lots varied in yielding capacity (Table 2). The grain yield varied within trial sites and be- tween years. However, the ranking of seed lots was similar over the years and sites and no significant interaction between seed lots, trial sites and years was recorded. CCS produced the highest grain yield, followed by seed lot FSS>2.7 mm + dis. These Table 1. Single grain weight (SGW) and germination rate (%) of seed categories. +, disinfectant treatment; - no disin- fectant treatment. Year Cultivar Seed lot Seed lot abbreviation SGW mg Germination % Disinfectant 2007 Saana farm saved seed (FSS) FSS 38.8 96 - 2007 Saana downgraded FFS FSS<2.5 mm 30.7 96 - 2007 Saana upgraded FSS FSS>2.7 mm 48.0 96 - 2007 Saana upgraded + disinfected FFS FSS>2.7 mm + dis 48.0 96 + 2007 Saana commercial certified seed CCS 51.2 94 + 2008 Annabell farm saved seed (FSS) FSS 41.0 89 - 2008 Annabell downgraded FFS FSS<2.5 mm 32.7 89 - 2008 Annabell upgraded FSS FSS>2.7 mm 45.3 89 - 2008 Annabell upgraded + disinfected FFS FSS>2.7 mm + dis 45.3 89 + 2008 Annabell commercial certified seed CCS 50.7 92 + 2009 Annabell farm saved seed (FSS) FSS 41.7 91 - 2009 Annabell downgraded FFS FSS<2.5 mm 37.2 91 - 2009 Annabell upgraded FSS FSS>2.7 mm 43.6 91 - 2009 Annabell upgraded + disinfected FFS FSS>2.7 mm + dis 43.6 91 + 2009 Annabell commercial certified seed CCS 50.7 92 + CCS = commercial certified seed; FSS = farm saved seed. A G R I C U L T U R A L A N D F O O D S C I E N C E A G R I C U L T U R A L A N D F O O D S C I E N C E Rajala, A. et al. Seed quality effects in barley 233232 Table 2. Seed lot effect on grain yield (kg ha-1), protein concentration (%), hecto liter weight (HLW, kg) and single grain weight (SGW, mg). Protein is shown at 0% moisture content, other results at 15%. Results are shown as means over year, tri- al site and genotype. The same lowercase letter indicates no statistical difference at p < 0.05 in the test of Bonferroni. Yield kg ha-1 Protein % HLW kg SGW mg FSS 5692 bc 11.6 a 67.3 a 44.8 a FSS<2.5 mm 5506 c 11.6 a 67.3 a 44.9 a FSS>2.7 mm 5820 b 11.6 a 67.2 a 45.2 a FSS>2.7 mm + dis 6126 a 11.3 b 67.3 a 44.9 a CCS 6346 a 11.3 b 67.4 a 45.3 a p-value < 0.001 < 0.001 0.948 0.612 sem 80.1 0.06 0.18 0.29 CCS = commercial certified seed; FSS = farm saved seed; sem = standard error of means. 100 200 300 400 500 0 1 2 3 4 5 counting seedlings/m 2 CCS FSS>2.7 mm + dis FSS>2.7 mm FSS<2.5 mm FSS a a b b a a b b a a b b 0.86 0.81 0.72 0.69 two seed lots expressed also higher seedling emer- gence rate when counted at Jokioinen trial site. Im- proved seedling emergence has likely a positive effect on yield performance (Steiner et al. 1989, López-Castaňeda et al. 1996). Seed restoration actions (up-grading and seed disinfection) of FSS improved yield performance. When comparing seed lots FSS>2.7 mm and FSS>2.7 mm + dis, seed disin- fection increased grain yield by 300 kg ha-1. This yield improvement is comparable with the results presented previously in other Nordic studies (Tah- vonen et al. 1995, Johnsson et al. 1998). CCS and FSS>2.7 mm + dis attained a slightly lower grain pro- tein concentration (%) as compared with other seed lots (Table 2). In contrast with the general protein requirements for feed and food, low pro- tein content is required in malting barley (Pelto- nen-Sainio et al. 2003). Yield and grain protein Fig. 2. Number of seedlings per square meter after different seed categories of cv Annabell. Counted at Jokioinen trial site 2008–2009. Countings were carried out at 5 days intervals. Numbers in the box indicate the ratio of realised and aimed seedling number. The same lowercase letter indicates no statis- tical difference at p < 0.05. CCS = commercial certified seed; FSS = farm saved seed. A G R I C U L T U R A L A N D F O O D S C I E N C E Rajala, A. et al. Seed quality effects in barley Vol. 20(2011): 228–234. 233232 are typically negatively correlated (Boonchoo et al. 1998), which was the case also in this study. Hence, any increase in grain yield using the same available growth resources (namely nitrogen) will likely result in reduction in grain protein concen- tration. Even moderate reduction in grain protein may determine whether yield ends up for feed or malting. This translates into a substantial difference in the value of the yield as malting barley attracts a higher price than feed barley. Despite of lower grain protein concentration in CCS and FSS>2.7 mm + dis seed lots, these two produced the highest protein yield (kg protein per hectare). This means more efficient use of nitrogen to build up grain yield. Other quality traits, like single grain weight (mg) and hectolitre weight (kg), were not affected by seed lot (Table 2). The seed weight effect was also emphasised in this experiment as both up- and down-grading of yielding capacity. FSS<2.5 mm was associated with a grain yield reduction of ca. 200 kg ha-1 when compared with FSS, ca. 300 kg ha-1 when com- pared with FSS>2.7 mm and of ca. 600 kg ha -1 when compared with FSS>2.7 mm + dis (Table 2). The seed weight effect on yielding potential is ambiguous, but some literature reports a positive correlation between them (Mikkelsen 1963, Hampton 1981, Chastain et al. 1995). Accordingly, grading of the seed lot seems to improve yield formation. FSS is often heterogeneous regarding seed weight (Pelto- nen-Sainio et al. 2011) and therefore grading is an important procedure for improving and stabilising the seed quality of FSS. FSS is used extensively by Finnish farmers (Fig. 1). A common reason for this is the low price paid for grain and farmers are apt to reduce pro- duction costs by using FSS. However, according to our results, CCS produced the highest grain yield. Also, good quality FSS, when it is graded and treated with disinfectant, can be comparable to the quality of CCS, but these restoration actions also increase the costs of FSS. To justify the use of more expensive seed (CCS or FSS>2.7 mm + dis) merely for economic reasons, the yield improve- ment needs to exceed the seed cost difference with unrestored FSS. The relatively strong fluc- tuations in cereal market price during recent years somewhat complicate the economic comparison between seed lots, and consequently a farmer’s decision making. In our estimations approxi- mately 150 to 250 kg ha-1 more grain is needed to cover the difference in cost between CCS and FSS>2.7 mm + dis, while 300 to 500 kg ha -1 covers the difference between CCS and unrestored FSS, and 100 to 200 kg ha-1 covers the difference between FSS>2.7 mm + dis and FSS. These rough threshold val- ues were met in this study (Table 2). The economic assessment of the situation changes even more to- wards a high quality seed advantage when other issues are taken into account. If other inputs (cul- tivation, fertilisation, plant protection) are used at a similar level, then the low quality seed with lower yielding potential inevitably reduces the input use- efficiency. This represents a drawback in economic as well as environmental terms. Conclusions In this study, seed quality had an apparent effect on plant stand establishment and yield. Differences were obtained despite similar germination rates for the various seed lots and identical seed rates of germinable seeds (500 germinating seeds m-2). Thus, differences in seedling emergence and yield performance were the outcome of variation in seed quality. Higher yield improves input use-efficiency, which is an important aspect of economical results and environmental impact of cereal production. Acknowledgements. The authors want to acknowl- edge the technical staff of Boreal Plant Breeding Ltd and MTT Plant Production Research, who participated in organizing the trials. The authors are grateful to Kylvösiemensäätiö (foundation) for financing the research. A G R I C U L T U R A L A N D F O O D S C I E N C E A G R I C U L T U R A L A N D F O O D S C I E N C E Rajala, A. et al. Seed quality effects in barley PB234 References Bonnett, O.T. 1961. The oat plant: Its histology and devel- opment. Bulletin 672. University of Illinois. Agricultural Experiment Station. 112 p. Boonchoo, S., Fukai, S. & Hetherington, S. E. 1998. Bar- ley yield and grain protein concentration as affected by assimilate and nitrogen availability. Australian Journal of Agricultural Research 49: 695–704. Chastain, T.G., Ward, K.J. & Wysocki, D.J. 1995. Stand establishment responses of soft white winter wheat to seedbed residue and seed size. Crop Science 35: 213–218. 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