Agricultural and Food Science in Finland, Vol. 12 (2003): 95–105 95 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 I N F I N L A N D Vol. 12 (2003): 95–105. Yield potential of chive: Effects of cultivar, plastic mulch and fertilisation Terhi Suojala MTT Agrifood Research Finland, Plant Production Research, Horticulture, Toivonlinnantie 518, FIN-21500 Piikkiö, Finland, e-mail: terhi.suojala@mtt.fi Chive is a perennial herb, growing also natural in Finland. Commercial production of the herb is very small in our country, but large amounts of chive are imported. This fact has aroused interest in inves- tigating the opportunities of producing chive using modern cultivation techniques. Effects of cultivar, plastic mulch as ground cover and fertilisation on yield were studied in field experiments over three y e a r s . I n t h e e x p e r i m e n t s , t h e m o s t p r o d u c t iv e c u l t iva r s o r p o p u l a t i o n s ( a F i n n i s h population “Hankoniemi”, a Dutch population “Tavallinen” and a German cultivar ‘Grolau’) pro- duced 10–20% higher yields than the less productive cultivars. There were no clear differences in the yield quality between the cultivars. Black plastic mulch was effective in increasing yield, controlling weeds and maintaining soil moisture. For fertilisation, the experiments revealed the high nutrient demand of chive. After the basic soil fertilisation, weekly fertigation with a NPK fertiliser at a higher nitrogen dose (10–15 kg ha-1 N per week) resulted in higher biomass production than fertigation with nitrogen alone and/or a half nitrogen dose. In the years following the planting, the annual uptakes in yield were 185–200 kg ha-1 for nitrogen, 17–20 kg ha-1 for phosphorus, and 120–140 kg ha-1 for po- tassium in the most intensively fertilised treatment producing the highest yield. The results show that chive is feasible for commercial production with modern cultivation techniques. Key words: Allium schoenoprasum L., chives, fertigation, culinary herbs, mulches, nitrogen, cultivars © Agricultural and Food Science in Finland Manuscript received May 2003 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 I N F I N L A N D Vol. 12 (2003): 95–105. Introduction Chive (Allium schoenoprasum L.) is a tradition- al perennial herb grown in nearly all home gar- dens in Finland. It also grows in natural habitats in coastal Finland, and is thus well adapted to Finnish conditions. However, large amounts of freeze-dried or dried chive are imported to Fin- land for food industry and retail. Our research aimed at exploring the opportunities of produc- ing chive in larger areas and at developing mod- ern cultivation techniques for commercial pro- duction. Reports on previous research on growing chive are very scarce. All over the world, chive mailto:terhi.suojala@mtt.fi 96 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 I N F I N L A N D Suojala, T. Yield potential of chive is only a minor crop. According to Poulsen (1990), the commercial production area is glo- bally no more than 1,000 hectares. Breeding of chive has concentrated on cultivars suitable for forcing in greenhouse, not for field production (Poulsen 1990). Cultivars grown in open field a r e u s u a l l y n o t u n i f o r m . S o m e h y b r i d cultivars have been bred which have higher plants, larger leaves and higher yield than open- pollinated cultivars (Tatlioglu and Wricke 1980). Fertilisation demand was studied by Hart- mann (1966), but since then, great changes have taken place as far as cultivars and cultivation technology are concerned. Poulsen (1990) gave the following instructions for fertilisation: 11 kg ha-1 P and 83 kg ha-1 K in spring, and there- after nitrogen at the rate of 10–12 kg ha-1 per week, totalling 220 kg ha-1 per year. The aim of the present research was to eval- uate the yield potential of chive when using modern cultivation techniques. The more specific objectives were to analyse which cultivars pro- duce the highest yield of good quality and to estimate the benefits of using black plastic as mulch. In another experiment, the objective was to analyse the amount of nutrients taken away from field in yield and to develop a suitable fer- tilisation programme for the seasons following the planting. Material and methods Field experiments were conducted at the MTT Horticulture facilities at Piikkiö (60°23’N, 22°30’E). The soil was fine sand, rich in organ- ic matter. Oats were grown as precrop. Prior to planting, the soil was enriched with dark peat (10 cm layer) that was limed (10 kg m-3 peat) and incorporated into soil. For basic fertilisation, the whole experimental area was fertilised with a compound fertiliser including 60 kg ha-1 N, 24 kg ha-1 P and 102 kg ha-1 K (plus other mac- ro- and micronutrients). In addition, to improve the nutrient status of the soil, micronutrients were added in form of a special fertiliser. Soil nutrient contents prior to and in the course of the experiment are presented in Table 1. Table 1. Soil nutrient contents (mean ± standard deviation, if available) before the experiment and at the end of each growing season. Date pH Conductivity Ca K Mg P B Cu Mn Zn 10 x mS cm-1 mg l-1 mg l-1 mg l-1 mg l-1 mg l-1 mg l-1 mg l-1 mg l-1 25 Apr 2000 6.8 ± 0.14 0.8 ± 0.07 1425 ± 7.1 111 ± 0.7 126 ± 5.0 17 ± 0.7 0.4 ± 0.07 4.1 ± 0.07 5.5 ± 0.14 1.6 ± 0.29 Fertilisation experiment (NPK2) 7 Sep 2000 6.3 1.6 1603 108 185 20 6 Sep 2001 6.5 1.0 1200 78 147 16 23 Aug 2002 N1 6.7 0.6 1330 41 134 12 N2 6.7 1.2 1540 51 175 14 NPK1 6.6 0.8 1190 69 150 11 NPK2 6.8 1.1 1240 151 152 22 Cultivar experiment 23 Aug 2002 6.8 ± 0.28 1.0 ± 0.07 1450 ± 141 85 ± 12.4 170 ± 12 16 ± 0.7 N1 – nitrogen fertiliser, single dose N2 – nitrogen fertiliser, double dose NPK1 – NPK fertiliser, single dose NPK2 – NPK fertiliser, double dose 97 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 I N F I N L A N D Vol. 12 (2003): 95–105. Chive was propagated from seeds sown in greenhouse on 11 April 2000. Eight seeds per a 5 x 5 cm cell were sown, and typically, 5–7 plants emerged. Plants were grown in green- house for six weeks and planted to the open field on 22 and 23 May. They were planted in double rows, with a distance of 30 cm between the rows and 20 cm between the plants. Double rows were 120 cm apart. Drip irrigation tubes were installed in the middle of the double row at the depth of 5 cm. Meteorological data of the experimental years are given in Table 2. Growing seasons 2001 and 2002 were warmer than the long-term aver- age. Precipitation in the first two seasons was close to the average values, but growing season 2002 was characterised by an extremely low pre- cipitation in early and late summer and high rain- fall in July. Soil moisture content was monitored by four tensiometers, installed in the depths of 15 and 40 cm in the cultivar experiment. Irrigation threshold was set at 0.05 MPa. However, soil tension never exceeded 0.02 MPa due to rainfall and water given by fertigation (3.9 litres per 1 row metre at each fertigation). Cultivar experiment Six cultivars or populations were included in the cultivar experiment. Four of them were proper cultivars, ‘Finbladet’ and ‘Triumpf ’ bred by the Danish company L. Daehnfeldt and ‘Grolau’ and ‘Wilau’ bred by the German company Sperli. “Hankoniemi” was a Finnish population taken into cultivation in 1920s, and “Tavallinen” was a cultivated Dutch population. The experimen- tal design included mulch (black plastic vs. no mulch) in whole plots and cultivar in subplots. Whole plots were arranged in randomised com- plete block design with four replicates. Subplots with a width of one row (1.2 m) and length of 6 metres were separately randomised within each whole plot. Fertilisation experiment In the fertilisation experiment, different fertili- sation treatments were compared after an uni- form pre-planting fertilisation. The aim was to find out if adding nitrogen alone is sufficient or if other nutrients are needed as well. Also, the effects of two different nitrogen doses were com- pared. The four fertilisation programmes were initiated after the first harvest in 2000. Fertiga- tion was accomplished by drip irrigation. Ferti- lisation treatments were separately randomised in four blocks. The plots were one row (1.2 m) wide and 14 metres long. Cultivar Grolau was used in the experiment, and the growing beds were covered by black plastic. Fertilisation treatments were as follows (see Table 3): nitrogen fertiliser, single dose (N1), nitrogen fertiliser, double dose (N2), NPK fer- tiliser, single dose (NPK1) and NPK fertiliser, double dose (NPK2). The amount of nitrogen Table 2. Monthly mean temperature and precipitation in the experimental years and the long-term averages. Month Mean temperature, °C Precipitation, mm 2000 2001 2002 1971–90 2000 2001 2002 1971–90 April 6.0 5.0 5.2 3.1 38 58 4 37 May 10.2 9.1 11.4 9.6 26 20 6 35 June 13.5 14.0 16.3 14.4 51 37 61 47 July 16.3 19.6 18.7 16.6 131 101 115 77 August 15.1 16.2 18.5 15.3 68 54 9 78 September 9.5 12.3 10.9 10.4 21 119 8 64 98 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 I N F I N L A N D Suojala, T. Yield potential of chive used in treatments N1 and NPK1 was doubled in treatments N2 and NPK2. The amounts of nutrients given varied between years; in 2000, f e r t i g a t i o n s t a r t e d fi r s t i n J u l y a f t e r t h e initial harvest. In the second year, doses were increased due to the low nitrogen status in soil. In 2002, fertigation ceased after the last harvest in August, and consequently, the fertigation times were fewer and the total nutrient am- ount was lower than in the preceeding year (Table 3). Fertigation was given once a week after the first harvest in the planting year, continuing to the last harvest in each year. In the second and third years, fertigation started in the beginning of May and, only at the time of flower stalk growth, one fertigation was omitted. Calcium nitrate (nitrate-N 15.5%, Ca 19%, Kemira Agro Ltd., Finland) was used as nitrogen fertiliser. In NPK treatments in 2000 and 2001, a com- mercially available compound fertiliser (Puu- tarhan täyslannos: nitrate-N 7.6%, urea-N 7.1%, P 5%, K 21%, S 1.8%, Mg 1.4%, Fe 0.1%, B 0.02%, Cu 0.01%, Mn 0.1%, Zn 0.01%, Mo 0.002%, Co 0.001%, Kemira Agro Ltd.) was applied every other week and calcium nitrate the other weeks. In 2001, NPK fertiliser was changed in order to improve the magnesium and potassium supply. Mixture of a compound fer- tiliser (Puutarhan hydrolannos: nitrate-N 6%, P 5%, K 26%, S 4%, Mg 2.7%, Fe 0.2%, B 0.02%, Cu 0.01%, Mn 0.1%, Zn 0.01%, Mo 0.002%, Co 0.001%, Kemira Agro Ltd., Finland) and magnesium nitrate (Mg 9.5%, nitrate-N 11%) was applied every other week, alternating with calcium nitrate. Measurements Yield was harvested in 6 m2 plots in 2000 and in 3.6 m2 plots in the following years. There were two harvests in 2000 and four harvests in 2001 and 2002 each. Yield from the mulched plots in the cultivar experiment was graded in order to estimate the saleable percentage of yield. Sam- ples were taken from every yield to analyse the dry matter content. In the cultivar experiment, they were taken from the mulched plots, and in the fertilisation experiment from the plots with treatment NPK2. Samples were dried at 70°C to constant weight. In the fertiliser experiment, soil nutrient con- tent was monitored by samples taken from the vicinity of the chive rows at 2–4 weeks’ inter- vals. Soil mineral nitrogen was analysed reflec- tometrically using Reflectoquant Ammonium and Nitrate Tests (Merck, Germany) and other nutrients by advisory soil tests (Soil Analysis Service Ltd., Mikkeli, Finland). Plant samples taken for dry matter analyses at each harvest were later on analysed for N, P and K concen- trations in order to estimate the amount of nutri- ents taken away from field in yield. N was meas- Table 3. Dosage of N, P and K in different fertilisation treatments and in the cultivar experiment. Year Number of fertilisations N-P-K (kg ha-1) in different treatments N1 N2 NPK1 NPK2 Cultivar exp. 2000 Basic fertilization 60–24–102 60–24–102 60–24–102 60–24–102 60–24–102 4 fertigations 20–0–0 40–0–0 20–3.5–15 40–7–30 20–0–0 Total in 2000 80–24–102 100–24–102 80–27.5–117 100–31–132 80–24–102 2001 16 fertigations 97–0–0 195–0–0 97–16–67 194–32–134 97–12–52 2002 14 fertigations 85–0–0 170–0–0 84–15–78 167–30–156 84–15–78 N1 – nitrogen fertiliser, single dose N2 – nitrogen fertiliser, double dose NPK1 – NPK fertiliser, single dose NPK2 – NPK fertiliser, double dose 99 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 I N F I N L A N D Vol. 12 (2003): 95–105. ured by means of the macro-Kjeldahl method. P and K samples were ashened at 450°C and the ashes were dissolved in HCl. P was measured colorimetrically using an ammonium-vanadate- molybdate method and K was determined by an atomic absorption spectrophotometer. Plant nu- trient analyses were performed at MTT Soils and Environment. Statistical analysis Variables subjected to the analysis of variance were total yields at each harvest and the annual total yields in both experiments. In the cultivar experiment, the saleable percentage of yield from the mulched plots was also analysed. In the cultivar experiment, a mixed model for split-plot design was used for the analysis of to- tal yield. Saleable percentages were only calcu- lated for the mulched plots, and consequently, only the effect of cultivar as a fixed factor was included in the model (assuming block as a ran- dom factor). Similarly, the fertilisation experi- ment was analysed using a mixed model with treatment as a fixed factor and block as a ran- dom factor. Estimated means for cultivars were further compared by Tukey’s test. In the fertili- sation experiment, contrasts were utilised to compare the overall effect of nitrogen vs. NPK fertiliser (N1 and N2 vs. NPK1 and NPK2) and single vs. double dose (N1 and NPK1 vs. N2 and NPK2). The SAS MIXED procedure (Littell et al. 1996) was used to fit the model by the restricted maximum likelihood estimation method. Resid- ual analyses did not indicate any cross depar- tures from the assumptions of the models. In the first yield in 2001, data from mulched plots in block 4 were omitted due to a fertilisation error. In addition, there was one observation missing in the data on the saleable percentages. Nutrient concentrations and uptakes were measured only in one treatment and no statisti- cal analyses were performed. Data are present- ed as means over four replicates (± standard de- viation). Results Mulch Use of black plastic mulch turned out to be prof- itable both for yield and weed control. The only exception to this positive influence was the sta- t i s t i c a l l y s i g n i f i c a n t l y l ow e r y i e l d i n t h e first harvest in the planting year: plastic mulch decreased the yield by 15% in comparison with bare soil (Table 4). In the second and third years, mulch increased the yield, although the effect was not always statistically significant. The greatest positive effect of mulch was measured in the first harvest in 2001: yield from the mulched plots was up to 63% higher than yield from the bare soil. This was the only harvest in which the effect of mulch was not similar for all cultivars. This interaction was due to the unusu- al response of cultivar Triumf which, in contrast to the other cultivars and populations, did not benefit from usage of mulch. Cultivars Cultivars and populations showed differences in yield each year (Table 4). The effect of cultivar on yield was statistically significant for the s e c o n d h a r ve s t i n t h e p l a n t i n g y e a r a n d most harvests in the following years. Moreover, cultivars showed similar differences in the an- nual total yields. Cultivars and populations could be divided into two g roups: “Tavallinen”, “Hankoniemi” and ‘Grolau’ produced higher yields each year, whereas ‘Finbladet’, ‘Triumf ’ and ‘Wilau’ had 10–20% lower total yields. Saleable proportion of total yield was calcu- lated for yields of mulched plots. There were very few statistically significant differences in the saleable percentage between cultivars. In the second yield in 2000, “Hankoniemi” had the low- est saleable percentage (88.0%, standard error of the mean = SEM 1.15) but the differences were not very large (Fig. 1). In the first yield in 2001, “Hankoniemi”, ‘Triumf ’ and ‘Finbladet’ had the 100 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 I N F I N L A N D Suojala, T. Yield potential of chive Table 4. Total yields (1 000 kg ha-1) of different cultivars and mulch treatments in the harvests in 2000–2002. Cultivar /Mulch in 2000 19–21 Jul 29 Aug – 1 Sep Total “Tavallinen” 5.63 14.13 ab 19.76 “Hankoniemi” 5.37 14.43 a 19.80 ‘Finbladet’ 4.72 12.98 ab 17.70 ‘Triumf’ 5.17 13.35 ab 18.53 ‘Grolau’ 5.15 14.33 a 19.47 ‘Wilau’ 5.26 12.30 b 17.57 SEM 0.337 0.473 0.622 Mulch 4.81 13.17 17.97 No mulch 5.63 14.00 19.63 SEM 0.239 0.356 0.385 P (Mulch) 0.041 0.185 0.043 P (Cultivar) 0.410 0.008 0.030 P (M x C) 0.406 0.922 0.860 Cultivar/Mulch in 2001 21 May 2–3 Jul 31 Jul – 1 Aug 3–4 Sep Total “Tavallinen” 5.18 a 6.07 a 10.40 10.12 a 32.07 a “Hankoniemi” 5.61 a 5.95 ab 9.98 9.17 ab 31.12 ab ‘Finbladet’ 3.82 bc 5.10 b 9.48 8.74 ab 27.36 b ‘Triumf’ 3.56 c 5.49 ab 9.53 8.54 b 27.72 ab ‘Grolau’ 4.80 ab 5.81 ab 10.34 9.48 ab 31.05 ab ‘Wilau’ 3.17 c 5.25 ab 9.88 8.85 ab 27.52 b SEM 0.355 0.252 0.355 0.632 1.372 Mulch 5.42 5.90 10.25 10.33 32.74 No mulch 3.30 5.32 9.63 7.97 26.21 SEM 0.284 0.189 0.265 0.764 1.139 P (Mulch) 0.013 0.041 0.197 0.117 0.017 P (Cultivar) <0.001 0.009 0.255 0.046 0.005 P (M x C) 0.021 0.359 0.293 0.425 0.443 Cultivar/Mulch in 2002 21–22 May 26 Jun 24–26 Jul 20–21 Aug Total “Tavallinen” 6.54 ab 7.16 ab 6.14 6.07 25.89 “Hankoniemi” 7.46 a 7.72 a 6.69 7.06 28.92 ‘Finbladet’ 5.42 bc 6.13 b 6.04 6.47 24.06 ‘Triumf’ 4.73 bc 6.62 ab 5.96 6.25 23.56 ‘Grolau’ 6.21 ab 7.06 ab 6.54 6.52 26.33 ‘Wilau’ 4.26 c 6.56 ab 6.56 6.79 24.17 SEM 0.450 0.322 0.504 0.531 0.143 Mulch 5.81 7.43 6.90 6.57 26.70 No mulch 5.73 6.32 5.75 6.48 24.27 SEM 0.260 0.186 0.443 0.419 0.993 P (Mulch) 0.826 0.024 0.089 0.872 0.100 P (Cultivar) <0.001 0.026 0.604 0.664 0.050 P (M x C) 0.216 0.523 0.927 0.717 0.663 Cultivar means followed by a common letter do not differ significantly (P = 0.05). Probability values (P) are given for the effects of cultivar, mulch and their interaction. SEM = standard error of the mean. highest saleable proportion, and in the fourth yield, cultivars Triumf, Finbladet and Wilau. In the last year, quality differences were statisti- cally significant only in the second yield in which ‘Triumf ’ and ‘Finbladet’ showed the best quali- ty. The data do not provide any clear trends in 101 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 I N F I N L A N D Vol. 12 (2003): 95–105. yield quality between cultivars, but whenever differences were observed, cultivars Triumf and Finbladet were usually of better quality than the other cultivars or populations. More striking than variation between the cul- tivars was the sharply decreasing trend in yield quality towards the end of the experiment (Fig. 1). In the last two harvests in 2002, only 45–59% of the yield (SEM 2.7–3.6) was salea- ble, in comparison with 76–94% (SEM 1.2–3.4) in the first year. The quality was impaired by dry or yellow leaf tips, light leaf colour or withered leaves. Fertilisation Fertilisation treatments, which started after the first harvest, had a strong effect on the yield (Ta- ble 5). Immediately in the second yield in 2000, the higher nitrogen dose increased the yield, while NPK fertiliser slightly decreased yield, in comparison with nitrogen alone. The same phe- nomenon was seen in the first yield in 2001. Otherwise, the double nitrogen dose increased yield in all harvests in the second and third years, and NPK fertiliser produced higher yield than nitrogen alone in the fourth harvest in 2001 and in the third and fourth harvests in 2002. Nutrient uptake Nutrient concentrations and nutrient uptake in yield were only measured for treatment NPK2. Nutrient concentrations showed some variation between the harvests which, together with the varying biomass accumulation, resulted in dif- ferences in nutrient uptake levels (Table 6). In t h e p l a n t i n g y e a r, w h e n o n l y t wo y i e l d s were harvested, nutrient uptake was quite low in comparison with the amount of nutrients given in fertilisers. In the subsequent two years, the total nutrient uptake in yield was 185–201 kg ha-1 for nitrogen, 17–20 kg ha-1 for phosphorus and 123–138 kg ha-1 for potassium. Fig. 1. Saleable proportions (% of total yield) of different cultivars in mulched plots. 102 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 I N F I N L A N D Suojala, T. Yield potential of chive Discussion Chive, an old traditional herb, turned out to have a considerable yield potential when efficient cultivation practices were used. Due to the sig- nificant effect of fertilisation level on biomass accumulation, the potential chive yield may have been approached in the most intensively ferti- lised treatment of the fertilisation experiment. T h e r e f o r e , a n n u a l b i o m a s s y i e l d s u p t o 2 0 0 0 0 k g h a - 1 i n t h e p l a n t i n g y e a r a n d 50 000 kg ha-1 in the subsequent years are achie- veable. The saleable yield is not equally high, b u t ev e n t h a t wa s e s t i m a t e d t o r i s e t o 15 000 kg ha-1 in the year of planting and to 30 000–40 000 kg ha-1 in the following years in good growing conditions. The figures are much higher than the fresh yields typical in Denmark, 7 500 kg ha-1, and New Zealand, 4 500 kg ha-1, as given by Poulsen (1990). However, in New Zealand seeds are collected from the same plants, which lowers the leaf yield. It seems evident that it is not economical to maintain the chive stand for longer than three years, which was also re- ported by Balvoll (1995), since the quality of yield diminished dramatically towards the end of the experimental period. In the cultivar experiment, the yield poten- tial of the cultivars and populations was proba- Table 5. Total yields (1 000 kg ha-1) in the fertilisation experiment. Fertilisation in 2000 19–21 Jul1) 29 Aug – 1 Sep Total N1 4.32 14.59 18.91 N2 4.54 16.99 21.52 NPK1 4.46 13.10 17.56 NPK2 4.19 14.39 18.58 SEM 0.015 0.085 0.092 P 0.442 0.053 0.054 N vs. NPK 0.507 0.037 0.036 Single vs. double dose 0.860 0.055 0.068 Fertilisation in 2001 21 May 2–3 Jul 31 Jul – 1 Aug 3–4 Sep Total N1 7.02 5.77 9.83 9.87 32.49 N2 8.22 6.69 14.70 14.06 43.66 NPK1 6.35 6.03 10.75 10.77 33.90 NPK2 7.41 7.13 15.87 18.53 48.95 SEM 1.075 0.461 0.906 0.937 2.981 P 0.013 0.059 <0.001 <0.001 0.001 N vs. NPK 0.041 0.310 0.185 0.019 0.155 Single vs. double dose 0.005 0.013 <0.001 <0.001 <0.001 Fertilisation in 2002 21–22 May 26 Jun 24–26 Jul 20–21 Aug Total N1 7.15 7.76 6.09 7.18 28.18 N2 11.60 12.36 8.84 8.72 41.53 NPK1 7.09 8.96 8.05 9.37 33.46 NPK2 11.66 15.23 13.14 13.47 53.49 SEM 1.185 1.310 0.673 0.738 3.519 P 0.005 0.005 <0.001 <0.001 0.002 N vs. NPK 0.998 0.111 0.001 <0.001 0.023 Single vs. double dose <0.001 0.001 <0.001 0.002 <0.001 Probability values (P) are given for the effect of treatment and for the contrasts (N vs. NPK and single vs. double N dose). SEM = standard error of the mean. 1) Fertilisation treatments started after the first harvest. 103 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 I N F I N L A N D Vol. 12 (2003): 95–105. bly not fully revealed because the fertilisation apparently was insufficient, in the light of the fertilisation experiment. This is, however, not likely to have interfered with the comparison of cultivars. Cultivars and populations had differ- ences in yield, but externally they looked much alike: it was very difficult to distinguish the cul- tivars visually in the field. It was also surprising that, in the most productive cultivars, there was only one proper cultivar while the other two “cul- tivars” were actually cultivated populations. The Finnish natural population Hankoniemi was one of the most productive populations which may reflect its good adaptation to the Finnish climate. The use of plastic mulch as ground cover in- creased the total yield during the growing cycle. Surprisingly, the first yield after planting was lower in mulched plots. A possible reason for this yield decrease may be the excessively high temperature in the root layer under the black plastic. Although the weather was not very warm in early summer 2000, there were 23 days with maximum temperature over 20°C and three days with maximum temperature over 25°C before the first harvest. Apart from the negative influence in the planting year, plastic mulch resulted in such a notable yield increase in the following years that it can be regarded beneficial to growth. Further positive effects of mulch include a con- siderable saving of work in manual weed con- trol (no herbicides are allowed on chive in Fin- land) and the even moisture content in soil. The fertilisation experiment revealed the high nutrient demand of chive when producing a great biomass. The nutrient status of the soil, espe- cially its potassium content, was only moderate in the beginning of the experiment, and it con- tinuously decreased over the years (Table 1). In addition, mineral nitrogen content in soil re- mained low after the first autumn (data not shown). In these conditions, the fertilisation pro- gramme with a higher dose of NPK fertiliser seemed suitable. In soils with higher initial nu- trient status, lower amounts of fertilisers may be sufficient. Wilson (1995) reported that nitrogen application of 67 kg ha-1 produced the highest yield when only one yield was harvested in the planting year. Hartmann (1966) found that high nitrogen supply 5–6 weeks after planting inhib- ited division of plants which resulted in reduced growth. Later in the season, high nitrogen level (up to the annual rate of 300 kg ha-1) favoured growth and improved leaf colour. The importance of using a NPK fertiliser, Table 6. Dry matter and nutrient contents and nutrient uptake of chive (mean ± standard deviation) in treatment NPK2 (NPK fertiliser, double dose). Year Harvest Dry matter, Nutrient content, mg g-1 dry matter Nutrient uptake in yield, kg ha-1 % N P K N P K 2000 1 10.8 ± 0.2 34.4 ± 2.3 2.71 ± 0.12 19.7 ± 1.3 16.2 ± 0.5 1.3 ± 0.07 9.3 ± 0.8 2 11.8 ± 0.8 23.9 ± 3.1 2.43 ± 0.31 19.3 ± 0.8 40.4 ± 9.1 4.1 ± 0.99 32.5 ± 5.2 Total 56.6 ± 8.8 5.4 ± 1.02 41.8 ± 5.5 2001 1 12.0 ± 0.6 32.9* 2.90* 21.9* 29.1 ± 5.4 2.6 ± 0.48 19.4 ± 3.6 2 13.2 ± 0.8 36.7 ± 3.4 2.96 ± 0.16 24.6 ± 1.5 34.3 ± 5.0 2.8 ± 0.24 23.0 ± 2.7 3 12.5 ± 0.9 30.9 ± 2.9 2.84 ± 0.26 20.8 ± 1.5 60.9 ± 11.3 5.6 ± 1.02 41.0 ± 6.6 4 10.6 ± 1.4 31.2 ± 4.1 2.91 ± 0.29 20.4 ± 1.8 60.4 ± 8.8 5.6 ± 0.75 39.5 ± 4.2 Total 184.8 ± 24.2 16.6 ±1.74 122.9 ± 12.7 2002 1 14.2 ± 0.9 27.5 ± 2.1 2.50 ± 0.19 21.3 ± 1.6 44.9 ± 10.8 4.0 ± 0.5 34.3 ± 4.7 2 11.4 ± 0.7 25.6 ± 2.5 2.55 ± 0.09 16.9 ± 0.4 44.3 ± 13.9 4.4 ± 1.2 29.1 ± 9.0 3 11.9 ± 0.6 32.9 ± 1.4 3.27 ± 0.14 22.2 ± 1.4 51.3 ± 8.5 5.1 ± 0.8 34.5 ± 5.8 4 13.1 ± 0.4 34.1 ± 1.4 3.39 ± 0.24 22.7 ± 1.7 60.0 ± 11.7 6.0 ± 1.0 40.1 ± 8.9 Total 200.6 ± 42.8 19.5 ± 3.33 138.1 ± 25.0 * Concentrations were not analysed. Figures are averages from the analyses of other harvests. 104 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 I N F I N L A N D Suojala, T. Yield potential of chive rather than nitrogen alone, became more evident towards the end of experiment, which coincided with the weakening nutrient status in soil. In the first two harvests after the start of fertigation, NPK fertilisers, however, slightly decreased the yield. This is difficult to explain, since the nu- trient solutions were not very strong, nor were nutrient contents or electrical conductivity in soil high. Although in soils with higher nutrient re- serves, high yield could be achieved by using nitrogen fertiliser alone after the first harvest, usage of a compound fertiliser might ensure bet- ter yield quality. For example, the importance of adequate supply of magnesium has been stressed in literature (Poulsen 1990). The effect of fertilisation on yield quality was not analysed in our experiment, but according to subjective observations, there were no clear differences in the overall quality between the treatments. In the last harvest in 2001, plants from the most inten- sively fertilised plots (treatment NPK2) started to fall down, which was not observed in the other harvests. Grading of chive after harvest is very time-consuming, wherefore any efforts to improve the external quality, e.g., by nutritional aids, should be further studied. In the years following the planting, nitrogen uptake in yield was roughly the same as the amount given in fertilisers the same year, phos- phorus uptake was 50–65% of the amount in fer- tiliser, and potassium uptake was approximately 90% of the amount in fertiliser. Thus, the ferti- liser efficiency was high. Fink et al. (1999) reported that chive yield of 35 tons ha-1 took up 175 kg ha-1 of nitrogen, 21 kg ha-1 of phosphorus and 158 kg ha-1 of po- tassium. In comparison with these figures, ni- trogen and phosphorus uptakes in our experiment were at similar levels, while potassium uptake was especially low, although the yield was higher than in the report of Fink et al. (1999). This al- lows us to assume that potassium uptake was weakened by the low potassium content in soil. Leaf nitrogen and potassium concentrations in our study are also much lower than those meas- ured by Wilson (1995). In conclusion, chive is a productive and win- ter-hardy herb the commercial production of which could well be increased in Finland. Culti- vars showed some differences in biomass pro- duction, and a Finnish population originating from the Southern coast was among the best- yielding cultivars. Black plastic mulch is recom- mended as ground cover. Chive biomass produc- tion is highly responsive to nutrient supply. Therefore, soils with good nutritional status should be preferred and sufficient nutrient lev- els should be applied in fertilisation. Acknowledgements. I wish to thank the members of the field vegetable team at Piikkiö for their skillful work, Yrkeshög- skolan Sydväst for the financial support, Janne Pulkkinen of Kemira GrowHow Ltd. for planning the fertilisation pro- grammes, and Tapio Salo and Leena Mäkäräinen of MTT Soils and Environment for conducting the nutrient analy- ses. References Balvoll, G. 1995. Grønsaksdyrking på friland. 5th ed. Oslo: Landbruksforlaget. 360 p. Fink, M., Feller, C., Scharpf. H.-C., Weier, U., Maync, A., Ziegler, J., Schlaghecken, J., Paschold, P.-J. & Stroh- meyer, K. 1999. Aktuelle Daten für Düngungsemp- fehlungen und Nährstoffbilanzen. Gemüse 10/1999: 576–578. Har tmann, H.D. 1966. Stickstoffdüngungsversuche zu Schnittlauch. Gartenbauwissenschaft 31: 51–63. Littell, R.C., Milliken, G.A., Stroup, W.W. & Wolfinger, R.D. 1996. SAS® System for Mixed Models. Cary, NC: SAS Institute Inc. 633 p. Poulsen, N. 1990. Chive Allium schoenoprasum L. In: Brewster, J.L. & Rabinowich, H.D. (eds.). Onions and allied crops. Vol. III. Boca Raton: CRC Press. p. 231– 250. Tatlioglu, T. & Wricke, G. 1980. Genetisch-züchterische Untersuchungen am Schnittlauch (Allium schoeno- prasum L.). Gartenbauwissenschaft 45: 278–282. Wilson, H. 1995. Yield responses and nutrient uptake of chive as affected by nitrogen, phosphorus, and po- tassium fertilization. Communications in soil science and plant analysis 26, 13&14: 2079–2096. 105 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 I N F I N L A N D Vol. 12 (2003): 95–105. SELOSTUS Lajikkeen, muovikatteen ja lannoituksen vaikutus ruohosipulin satoon Terhi Suojala MTT (Maa- ja elintarviketalouden tutkimuskeskus) Ruohosipuli on monivuotinen ja Suomessa luonnon- varainen yrttikasvi. Ruohosipulin kaupallinen tuotan- to on maassamme hyvin vähäistä, ja yrttiä tuodaan runsaasti maahan. Tästä heräsi kiinnostus selvittää mahdollisuuksia tuottaa kasvia tehokkaasti nykyaikai- silla viljelymenetelmillä. Lajikkeen, maanpinnan kat- teen ja lannoituksen vaikutuksia ruohosipulin satoon tutkittiin kolmivuotisissa kenttäkokeissa. Tutkitut la- jikkeet voitiin jakaa kahteen ryhmään: satoisimmat lajikkeet (kotimainen luonnonkanta Hankoniemi, hol- lantilainen viljelykanta Tavallinen ja saksalainen la- jike Grolau) tuottivat 10–20 % korkeammat sadot kuin muut lajikkeet. Sadon laadussa ei ilmennyt sel- viä lajike-eroja. Musta muovi maanpinnan katteena lisäsi satoa ja helpotti rikkakasvien hallintaa sekä maan kosteuden säilymistä. Peruslannoituksen jäl- keen viikottainen kastelulannoitus moniravinteisella lannoitteella ja korkeammalla typpimäärällä (10– 15 kg/ha N viikossa) tuotti suuremman biomassan kuin pelkän typpilannoitteen ja/tai puolet alemman typpimäärän käyttö. Istutusta seuraavina vuosina sa- don mukana poistui typpeä 185–200 kg/ha, fosforia 17–20 kg/ha ja kaliumia 120–140 kg/ha eniten lan- noitetussa ja suurimman sadon tuottaneessa käsitte- lyssä. Tulosten mukaan ruohosipuli on nykyaikaisil- la viljelymenetelmillä satoisa kasvi. 106 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 I N F I N L A N D Suojala, T. Yield potential of chive Title Introduction Material and methods Results Discussion References SELOSTUS