Evaluation of wheat cultivars/lines for terminal drought tolerance using drought tolerance and susceptibility indices.

In order to evaluate the performance of bread (Triticum aestivum L.) and durum (Triticum turgidum L. ssp. durum) wheat genotypes under drought stress conditions after anthesis and determination of the most suitable quantitative drought stress tolerance indices, this investigation was performed during 2011-12 and 2012-13 cropping season in Zarghan Agricultural Research Station. A number of 168 wheat lines/cultivars (166 bread wheat and 2 durum wheat) were evaluated in alpha lattice experiment with two replications under stress (no irrigation after anthesis) and full irrigation conditions. Results showed that Seymareh, Roshan and Yecora Rojo cultivars , under full irrigation and Seymareh, Roshan and Kapeti under stress conditions had maximum grain yield. With respect to positive and significant correlation of Harmonic Mean (HARM), Geometric Mean Productivity (GMP), Stress Tolerance index (STI), Mean Productivity (MP), Drought Resistance Index (DI), Yield Index (YI), Modified Stress Tolerance Index for stress (MSTIs) and Modified Stress Tolerance Index for irrigated conditions (MSTIp), with grain yield under stress (Ys) and full irrigation (Yp) conditions, this indices introduced as the best screening criteria in the experiment situations. Screening of drought tolerant genotypes was performed using Mean Rank and Rank standard deviation of selected indices, and Biplot analysis with regard to Principal Component Analysis (PCA). Finally, cultivars/lines of Seymareh, Roshan, Kapeti, Akbari and DN11 introduced as the most tolerant genotypes.