Evaluation of spring wheat genotypes using drought tolerance indices and principle component analysis

Drought stress is one of the most important environmental abiotic stresses that reduces crop yield especially in arid and semi-arid regions of the world. One of the useful strategies in regard to plant breeding for drought resistance is maintaining and exploiting the diversity that exists amongst different varieties. In order to identify the sources of resistance and drought tolerance indices، 39 varieties of spring wheat were cultivated in a split plot design with 3 replications in the Research Field of Faculty of Agricultur، Mohaghegh Ardabili University، Iran. Stress levels، which were arranged as the main plots، included control (full irrigation)، 2/3 of irrigation requirement and 1/3 of irrigation requirement. Varieties were considered as sub plots. Under 2/3 irrigation، Sepahan، karaj3، Bahar and Yavaroos were the best varieties in terms of the Stress Tolerance Index (STI)، Geometric Mean Productivity (GMP) and Harmonic Mean Productivity (HARM) indices; whereas under 1/3 irrigation، Hirmand، Bahar، Yavaroos and Marvdasht were the best ones based on the mentioned indices. Under non- stressed (control) conditions، the greatest grain yield correlation coefficient was obtained with STI، GMP and HARM، respectively، while under 2/3 irrigation، the greatest grain yield correlation coefficient was obtained with HARM، GMP and STI indices، respectively. Moreover، based on the biplot graph resulted from principle component analysis، in 2/3 irrigation، Moghan1، Golestan، Kavir، Maroon، Karkheh، Chanaab، Germezak، Tajan، Bahar and Sepahan; and in 1/3 irrigation، Golestan، Germezak، Niknejad، Maroon، Darab، Falat، Arta، Marvdasht، Bahar and Hirmand were the most tolerant genotypes.