Evaluation of rain-fed wheat (Triticum aestivum L.) genotypes for drought tolerance

Drought stress is one of the most important environmental stresses that have limited the production of wheat, especially in arid and semi-arid regions of the world. To recognize drought tolerant rain-fed wheat genotypes and to determine the best tolerance/susceptibility indices, a study was conducted at the Agricultural Research Station of Miandoab for two cropping years (2013-15). The experimental materials included 12 rain-fed wheat genotypes investigated in two separate field experiments based on randomized complete blocks design with three replications under both rain-fed and supplemental irrigation conditions. The combined ANOVA for grain yield and agro-physiological traits showed that there was a large genetic difference between wheat genotypes for grain yield and studied traits in response to drought stress among years and moisture regimes. The different drought tolerance/susceptibility indices were used to characterize drought tolerance of genotypes. Generally, a reduction of RWC in drought tolerant genotypes (genotypes 6, 2, 11, and 10) was lower compared to the sensitive genotypes (genotypes 4 and 8). Cluster analysis based on drought tolerance indices categorized genotypes into two main groups. The genotypes belonging to the cluster 1 could be introduced as tolerant to the drought conditions. According to MSI (Multiple scoring index), genotypes 10 (Seafallah/3/Sbn//Trm/K253) and Saein had the best combination of productivity and resistance to drought stress. The significant correlation between MSI with grain yield under drought conditions indicated the superiority of MSI as a useful tool for efficient selection of drought-tolerant genotypes. In the present study there was no significant correlation between RWC and RWL with MP, GMP, STI and MSI indices under both conditions.