Evaluation of Several New Bread Wheat Genotypes (Triticum aestivum L.) for Grain Yield and Its Components under Water Stress Conditions

Two experiments were conducted at the Agriculture Experimental Research Farm of the Faculty of Agriculture, Assiut University, in each of the two seasons 2011/2012 and 2012/2013. The first experiment was irrigated as needed (normal), while the second one irrigated only one time three weeks after sowing irrigation (drought stress). This work aims to evaluate 30 wheat genotypes (Triticum aestivum L.) and two check cultivars, namely, Giza 168 and Sakha 93 under normal irrigation and drought stress conditions. Separate analysis of variance revealed highly significant differences between the evaluated genotypes for all studied traits in the two seasons under each environment. Combined analysis of variance over seasons and environments revealed highly significant differences between seasons for no. of spikes/ plant and grain yield/plant. The mean squares due to environments, genotypes, (G x S) and (G x E) interactions were highly significant for all studied traits whereas the mean squares due to (G x S x E) interactions were highly significant for no. of spikes/ plant and grain yield/plant. Drought stress reduced spike length, number of spikes/plant, number of grainss/spike, 1000-grain weight and grain yield/plant by 5.04, 18.38, 9.40, 11.15 and 25.07%, respectively. The new genotypes Assiut 216, Assiut 238, Assiut 228, Assiut 726 and R 80 highly significantly surpassed the two check cultivars in grain yield/plant and some of correlated traits. The new genotypes Assiut 224, Assiut 248, Assiut 249, Assiut 406, Assiut 704 and MK 2-27 showed drought Susceptibility Index less than one and were considered tolerant to drought stress. It could be concluded that these genotypes can be used in wheat breading programs to improve grain yield and drought tolerance.