The Study of Seed Yield Stability and Drought Tolerance Indices of Bread Wheat Genotypes under Irrigated and Non-Irrigated Conditions

In order to study and assess the effects of drought stress on yield stability and drought tolerance indices in irrigated and non-irrigated conditions, this experiment was conducted in Sarableh and Mehran towns, Ilam province, in 2004 and 2005. The number of 12 genotypes of bread wheat was cultivated under two conditions, including: Non-stressed (irrigated) and drought stress conditions in a randomized complete design with 3 replications. Morphophysiological traits were measured or calculated depending on the type of each trait. The results indicated that plant height, 1000 kernel weight, Seed yield and harvest index were decreased by drought stress. Under drought stress condition, plant density and 1000 kernel weight had a high positive correlation with seed yield. In irrigated condition seed yield had a high positive correlation with harvest index. Regarding yield in stress and non-stress conditions, drought tolerance indices including MP, GMP, TOL, HARM, SSI and STI were calculated. This study indicated that MP, STI and GMP indices had highest correlation with seed yield and can be used for selecting tolerance variety. According to drought tolerance indices and cluster analysis, Mohammadi, Gahar, Nicknejad and Koohdasht varieties were the best and most tolerance genotypes and had the highest yield.