Evaluation of Seed Yield and Stress Tolerance Indices in Soybean Lines and Cultivars in Gorgan Area

Drought stress is the most important factor decreasing crop yield in dry and semi dry areas of the world, such as Iran. To investigate seed yield and drought stress tolerance indices of twenty soybean lines and cultivars, three experiments were conducted, each in a randomized complete block design with there replications, at Agricultural Research Station of Gorgan in 2010 and 2011. In the first experiment, all soybean genotypes were irrigated based on 50 mm and in the second and third experiments, the irrigation was based on 100 and 150 mm evaporation from evaporation pan, respectively. The mean seed yield of soybean genotypes in non-stress and stress conditions was 1989 and 1242 kgha-1, respectively lines. HT2 in non-stress conditions (2569 kgha-1), PE10 in moderate stress conditions (2222 kgha-1) and WE6 in severe stress conditions (1688 kgha-1) had the highest seed yield, respectively. With regard to GMP, MP and STI indices, drought stress tolerance of PE10 and HT2 genotypes were more than those of other genotypes. Based on SSI index, genotypes L504 and M9 had the highest and the lowest tolerance to drought stress, respectively, while according to TOL index genotypes SG20 and L17 were the most and the least tolerant genotypes, respectively. The superior genotypes can be recommended for further breeding programs.