Evaluation of tolerance of bread wheat (Triticum aestivum L.) genotypes to terminal drought stress based on some agronomic traits

Terminal drought stress reduces wheat grain yield in many parts of Iran. Selection of tolerant genotypes can eliminate the damage of this stress. Genotypes WS-82-9, Sirvan, WS-86-14, Pishtaz, Parsi, Back cross roshan, Arg, Roshan, Pishgam, Alvand and Mahdavi were evaluated under normal irrigation and terminal drought at Isfahan during 2011-2013. Traits grain yield, biological yield, harvest index and thousand grain weight were studied. Terminal drought stress significantly reduced all traits and stress intensity for the traits was 0.501, 0.259, 0.325 and 0.424 respectively. Genotypes had significant difference for all studied traits. Eleven susceptibility and tolerance indices and also the average rank of each genotype were calculated. Based on the grain yield, varieties of Phishgam, Sirvan, Alvand and WS-86-14 were four tolerant genotypes respectively, and Roshan was the most susceptible genotype. There were significant positive correlations between MP, GMP, STI, HM and MSTI(k1) with grain yield in both stress and non-stress conditions. There was significant positive correlations between grain yield with harvest index, showing the importance of harvest index. Based on harvest index, WS-86-14 and Roshan was the most tolerant and most succeptible genotype, respectively. Varieties of Pishgam and Sirvan can be recommended for cultivation in areas with probability of terminal drought strees.