The response of barley (Hordeum vulgare L.) genotypes to nitrogen fertilizer application under normal irrigation and drought stress conditions

Introduction In west Azerbaijan for food production including barley, water stress is one of the most important threats and water deficit stress at grain filling stage do it damage every year. One approach for reducing of damage of water deficit stress is introducing of drought tolerant new barley variety. Effect interaction of water and nitrogen is complicated on plant. Under full irrigation condition, rate of nitrogen for grain mostly grain yield determinative factor, but in water deficit stress condition, high rate of nitrogen increased severity of tension, as a result growth and yield of plant reduced. For achieving of drought tolerant barley genotype, barley genotypes must be evaluated in water deficit stress and full irrigation conditions. The aim of this research was to evaluate the response of barley genotypes to application of different levels of urea fertilizer under different moisture conditions. Material and methods This research was carried out in order to evaluate the response of barley genotypes to application of different levels of urea fertilizer under complete irrigation and end season drought stress conditions, as a split plot based on randomized complete blocks design with three replications at Miandoab Agricultural Research and Natural Resources Station during 2014-2016 crop seasons. Four barley genotypes (Bahman, EDBYT-82-6، EDBYT-82-9، EBYT-83-17، EBYT-84-10) at different levels of nitrogen (0, 50, 100, 150 kg/ha urea) were evaluated in full irrigation and grain filing water deficit stress conditions. At planting time, 50 kg/ha urea applied for all treatments. All genotypes were planted with 400 seed/m2 in 6 lines by 5m length and 20cm apart at late of October month. Watering in the fall for a turn to green seeds and their deployment was carried out. In the spring for water deficit stress trial, irrigation at the heading time was cut and for normal trial was performed three times irrigation. Seedbed Preparation, potash and phosphate fertilizer, crop care and harvest for all treatment were the same. Compound analysis of data was carried out on two years. The SAS (Ver, 9.4) and Minitab (V. 16) software were used to data analysis. Results The results of combined analysis showed that effect of year, genotype, nitrogen and year*genotype was significant at both irrigation conditions. Mean comparisons showed genotypes of Bahman and EBYT-84-10 genotypes had the greatest grain yield in both of irrigation conditions. Under normal irrigation condition, grain yield increased until 100 kg/ha urea, application of 150 kg/ha of urea had no significant difference comparison to 100 kg/ha urea in view of grain yield, 150 kg/ha of urea produced 35% greater grain yield rather than 0kg/ha treatment. Under water deficit condition, application of 100 kg/ha of urea had no significant difference comparison to 50 kg/ha in view of grain yield, also application of 150 kg/ha of urea decreased 11% grain yield comparison to 0kg/ha treatment. Selection of drought tolerant genotypes in different nitrogen levels based on principal components analysis indicated that genotype Bahman at 0 kg/ha, genotypes Bahman and EBYT-84-10 at 50 and 100 kg/ha, and genotype EBYT-84-10 at 150 kg/ha nitrogen application had the highest drought tolerance. Conclusion Results of this study showed response of barley genotypes varied to rate of nitrogen, so under water deficit stress condition, nutritional need of barley genotypes less than full irrigation condition. So, in addition to the raise cost for farmer may be infecting the environment. Therefore, recommended in selecting of drought tolerant barley genotypes, special attention focus to rate of nitrogen.