Evaluation of Soybean Cultivars as Water Deficit tolerance

Interaction of twenty soybean improved lines and cultivars to water deficit stress were evaluated in Karaj and Gorgan province in 1384 and 1385. Three experiments as base of RCBD were conducted in Karaj province each year. The experiments were irrigated after 50 (control), 100 (mild stress) and 150 mm (sever stress) evaporation from pan, class A. Two experiments as base of RCBD were conducted in Gorgan province each year. The experiments were irrigated after 50 (control) and 150 mm (sever stress) evaporation from pan, class A. In Karaj, combined analyses showed that drought had significant effects on morphological characteristics and growth of soybean. Water deficit stress caused to decrease plant height that was due to reducing of node number and internodes distance. Drought stress reduced seed yield. Decreasing of yield was for diminishing of seed number per square area. Seed weight was decreased, too. Drought occurrence reduced seed oil content and increased protein seed content. Harvest index were not affect by mild stress, but it was reduced, when stress was sever. Productivity effort was reduced by water stress, too. In control condition, Linford cv. produced the highest yield (2846 kg.ha-1) among cultivars. L11 line had the highest yield in mild stress and TNS 56 got the highest yield in severe stress condition. Correlation of yield in control and water deficit conditions with susceptible and tolerance indices showed that MP, GMP and STI had positive and significant correlation with yield in different conditions of water deficit. Therefore, L11, Clean and Linford were superior to others. In Gorgan province, the results showed that drought stress occurrence caused to plant height depletion that was due to reducing of internodes distance. Drought was reduced plant yield for reducing of seed weight, significantly. Pods number affected yield, little. Water deficit decreased seed oil and increased seed protein contents. TNS 56 and Davis x Williams produced 2204 kg.ha-1 and 1754 kg.ha-1 yield in control and sever stress condition, respectively. Combined analyses of data in provinces showed that TNS 56 cv. produced the highest yield in control and sever stress (2822 and 1728 kg.ha-1, respectively). Correlation between yield in control and severe drought stress condition and MP, GMP, STI were positive and significant. Therefore, TNS 56, Clean, Linford, Davis x Williams, L11 and Manokin were suitable in control and sever water defici