Investigation of water deficit stress effects on quality characteristics and oil yield of soybean

Investigation of environmental factors and stresses on the fatty acid composition of soybean oil and identification of water deficit tolerant cultivars is one of the strategies to improve the fatty acid composition of its oil.Effect of water deficit stress on quality characteristics and oil yield of 13 soybean genotypes were evaluated as a split plot based on randomized complete block design in three replicates in Karaj in two years.In this work irrigation was conducted at three levels including routine irrigation (control),mild and severe stress were based on 50, 100 and 150mm evaporation from ClassA evaporation pan, respectively,in main plots and soybean genotypes in sub-plots.The results showed that effect of year×irrigation×genotype on oil yield, oil content, oleic acid, linolenic acid and arachidic acid was significant.Oilyeild of soybean decreased under mild and severe stress, 27 and 38%, respectively.Saba and Williams×A3935 had the highest oilyield with an average of 422 and 427 kg/ha, respectively. palmitic acid in mild and severe stress compared to control irrigation decreased by2.6% and 1.2%.While stearic acid increased by9.5% and 10.8%in mild and severe stress conditions, respectively.In control irrigation, L425002 line with 0.22%, in mild stress conditions,Williams×Century and L425002 with 24.6% and 24.1%, and in severe stress conditions, Saba and L425002 genotypes with 24.1% and 24.5%, had the highest percentages of oleic acid and high oil content.In control irrigation, Saba cultivar,in mild stress conditions,Saba cultivar and Williams×A3935 and in severe stress conditions Williams×A3935 had the highest oil yield.L425002 and Williams×Century had the highest oil quality in all stress conditions.