Evaluation of bread wheat (Triticum aestivum) genotypes for tolerance to terminal drought stress

In order to study the genetic variation، identification and selection among wheat genotypes based on indices of drought stress، this experiment was conducted with 16 bread wheat genotypes that arranged a randomized complete block design and three replications in two normal and restricted irrigation at the Neishabour Agricultural Research Station during 2008-09 cropping season. Seven drought stress indices were Mean Productivity (MP)، Geometric Mean Productivity (GMP)، Harmonic Mean (HMP)، Stress Tolerance Index (STI)، Stress Susceptibility Index (SSI)، Tolerance Index (TOL) and Lin and Binns (Pi) method. The highest grain yield in stressed environment and the greatest values of MP، GMP، HARM، STI and Pi obtained in With regard to above mentioned indices and grain yield in two conditions، lines no. 2، 11 and 14 were the best tolerated drought stress genotypes. Analysis of correlation and mean grain yield in two conditions showed these indices suitable for screening genotypes under these conditions. Using multivariate biplot showed which genotypes no. 2، 11 and 14 were adjacent drought tolerance indices i. e. MP، GMP، HARM، and STI. Cluster analysis revealed genetically distance between genotypes، that genotypes no. 2، 11 and 14 as drought tolerated and genotypes no. 3، 8، 9 and 13 were susceptible to drought stress respectively.