ارزیابی تحمل به خشکی آخر فصل در برخی از ژنوتیپ های جو با استفاده از شاخص های تحمل به تنش خشکی

     Drought is one of the major environmental limiting factors in the global agriculture. Exploiting of crop yield potential and increasing yield stability of them in drought and drought-prone regions can be guaranteed to feed the world’s growing population. For this purpose, in order to assess the late season drought tolerance genotypes and determining of tolerant them using stress tolerance indices, 21 genotypes of barley in a Randomized Complete Block Design with three replications in two environments (stress and non-stress) in crop year 2014-2015 at the Agricultural Faculty of Tehran University in Karaj were tested. For stress creation, irrigation at first spikelet of inflorescence visible (Zadoks scale, code 50) was stopped. Genotypes yields in non-stress (Yp) and stress (Ys) measured and analysis of variance was performed on them. MP, GMP, STI and HARM indices which showed the highest correlation with yield in stress and non-stress conditions were introduced as superior indices for screening genotypes. The results of principle components analysis and biplot diagram showed that Rihan03, Yousef and Fajre30 had the highest, Rihan, Morocco-9-75 (susceptible control) and Sahra had the lowest drought tolerance genotypes respectively and D10 line had the highest yield in non-stress and was relatively tolerant. Cluster analysis based on MP, GMP, HARM, STI, TOL and SSI indices and yield under stress and non-stress conditions classified genotypes in six clusters. Most drought tolerant genotypes with high yield that their yield difference between stress and non-stress conditions was lower than the other genotypes, were located in sixth, fifth and fourth clusters and sensitive genotypes were located in first and third clusters. Based on the obtained results, Rihan03, Yousef and Fajre30 genotypes were late season drought tolerant, Nik, Kavir, Inc73 and Inc79 genotypes were relatively drought tolerant and Rihan, Morocco-9-75 (susceptible control), Sahra and Inc82 genotypes were identified as sensitive. Probably, D10 Line is also due to a very good yield in non-stress and medium in stress conditions has the potential to become a good commercial variety