Evaluation of drought tolerance in bread wheat lines using drought tolerance indices

In order to investigate the effects of terminal drought stress on yield, yield components and assimilate remobilization in 8 wheat cultivars and lines for introducing of drought tolerance and susceptible ones, two experimental separated designs were occur using randomized complete blocks with three replications. A field study was conducted in 2009 in Agriculture and Natural Resources Experiment Station of Markazi province. The first experiment was water stress in post flowering stage and second experiment was irrigation with normal regime. The yield and yield components, plant height, day to flowering, harvest index and peduncle length were measured in this study. Response of cultivars and lines under optimum irrigation and water stress conditions were different. Water stress reduced most traits a well as yield and yield components. Results showed that some cultivars at water stress condition, showed tolerance and had relatively high yield For example, lines C-84-4 and C-82-12 showed high more tolerance under optimum and water stress, condition lines C-78-14 and Shariar cultivar showed high yield at optimum irrigation and lines C-81-14 and C-83-7 showed high yield at water stress condition. In order to evaluate stress indices among cultivars and lines we used 6 indices such as harmonic mean (Harm), stress tolerance index (STI), tolerance index (TOL), Mean productivity (MP), stress susceptibility index (SSI) and Geometric mean productivity (GMP). Results showed that all of these indices were the best, because there were the greatest correlations between yield and harvest index under water stress and optimum irrigation.