Effects of Different Levels of Water Deficit Stresses on the Morphologic Properties of Root, Antioxidants Activity and the Seed Yield in Five Cultivars of Soybean (Glycine max L)

A two-year field experiment was studied for assessment responses of five soybean cultivars (L17, Clean, T.M.S, Williams*Chippewa, M9) to oxidative injuries and some antioxidants content in 2011 and 2012. The experimental design was split plot in a randomized complete block design with four replications. In this study, three levels of irrigation were applied based on 50 mm (S1; optimum condition of irrigation), 100 mm (S2; moderate water deficit) and 150 mm (S3; extreme water deficit) evaporation from class A pan. Results showed that, water deficit stresses was significantly increased contents antioxidants (superoxide dismutase and glutathione peroxidase) and root-shoot volume ratio, and also, was significantly decreased length and volume of roots. Among cultivars, L17 and Williams*Chippewa were produced the highest seed yield at the optimum condition of irrigation and both of water deficit stress levels. Assessment of correlation results indicated, there was positive and significant correlation between seed yield with antioxidants activity (superoxide dismutase and glutathione peroxidase) and there also was a negative and significant correlation between seed yield with root-shoot volume ratio.