عنوان مقاله [English]
To investigate the effect of terminal drought stress on wheat, 35 lines and varieties were evaluated as split plot arrangement based on randomized complete block design with three replications under normal irrigation (based on crop water requirement) and terminal drought stress (no irrigation from flowering stage) in Darab Agricultural Research Station in 2009. Drought stress (normal irrigation and terminal drought stress) and wheat genotypes were considered as the main and sub-plots, respectively. The studied traits were included grain yield, yield components and canopy temperature depression (CTD). To select drought tolerant varieties, five drought tolerance indices including stress susceptibility index (SSI), stress tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP) and tolerance (TOL) were also calculated. The results indicated that drought stress reduced grain yield and its components, so that average grain yield under normal and terminal drought stress conditions was 4691 and 3659 kg.ha-1, respectively. The correlation coefficients between grain yield and CTD at three measured stages from heading to physiological maturity as well as average CTD at all three stages under both normal and terminal drought conditions were moderate to relatively high. In total, the results of this research indicated that the CTD could be used as a rapid and effective criterion for screening high yielding genotypes in early generations of breeding programs. Evaluating drought tolerance indices also showed that the MP, GMP and STI are the more effective to select high yielding and drought tolerant varieties. All three indices identified the genotypes 14 and 16 as drought tolerant genotypes. These genotypes had the high yield in both normal and drought stress conditions.