Effect of final season drought tension on photosynthesis, seed yield and seed vigor of five soybean cultivars

In order to investigate the effect of terminal drought tension on seed yield and seed vigor of five soybean cultivars this factorial experiment with complete randomized blocks design in four replications was conducted in Dezful Safiabad region in 2011. The factors consisted of drought tension (50, 00 and 150 mm evaporation from evaporation pan) and five soybean cultivars. The results showed that in severe drought tension conditions, stress tolerance index Williams, Charelstone, Sahar, Hamilton and Safiabad cultivars was 0.70, 0.59, 0.42 0.32 and 0.35, respectively. Drought tension caused decreasing in grain yield and under severe drought tension conditions, the maximum soybean seed yield was observed in Willuliams cultivars to the amount of 112/2 gram per meter square the lowest amount of grain yield in Hamilton and Safiabad cultivars by the amounts of 83.8 and 82.1 gram per meter square. Under severe drought tension conditions, maximum leaf area, photosynthesis and chlorophyll concentration was observed in Williams and Charleston cultivars. Results indicated post flowering drought tension decreased seedling vigor, seed germination percentage and seedling growth of soybean cultivars. Under severe drought conditions, the highest seedling vigor was observed in Williams and Charleston cultivars by the amounts of 5/7 and 4/2, respectively. Results showed Williams and Charleston cultivars were tolerated drought tension conditions better than other cultivars.