Performance of Some Wheat (Triticum aestivum L.) Genotypes and their Drought Tolerance Indices under Normal and Water Stress

WATER drought stress is a major environmental stress limiting wheat productivity worldwide. The aim of this study was to assess and compare various stress tolerance indices in order to identify the most drought-tolerant wheat genotypes for the future wheat breeding programs. For this purpose, 28 bread wheat genotypes (7 parents and their 21 hybrids) were evaluated in two separate experiments under water-deficit (two irrigations) and well-watered (five irrigations). The drought tolerance indices were calculated based on grain yield under normal (Yp) and stress (Ys) conditions. Highly significant differences were detected among the tested genotypes for all the studied traits, under normal and water stress conditions. Water-deficit stress substantially declined the means of all the studied traits. Water stress caused reductions in days to 50 % heading, plant height, spike length, number of kernels / spike, 1000-kernel weight and grain yield / plant traits by 5.19, 11.15, 16.39, 16.90, 10.67 and 8.98 % respectively. Based on tolerance index (TO L) and stress tolerance index (SSI), the two parents Misr 2 and Line 117, as well as, the crosses Sids14 x Sakha 95, Sids14 x Line 117 and Misr 2 x Line 136 were identified as the suitable genotypes under water stress conditions due to lower values of these indices. Moreover, these genotypes expressed the highest yield under stress conditions. Therefore, the parental genotypes Sids 14 and Sakha 95, as well as the hybrids Sakha 95 x Misr 2 and Sakha 95 x line 115, were identified as highly drought-tolerant genotypes. Accordingly, these genotypes could be used in the future wheat breeding for improving grain yield under water deficit conditions.