Drought Tolerance in Wheat Using Stress Selection Indices

Drought is one of the most limiting abiotic stresses affecting wheat crops. It is a significant abiotic factor affecting the yield and yield stability of cereal crops, and it simultaneously affects many traits leading to yield reduction. The current research was conducted at the University of Agriculture, Peshawar, during 2021-2022. Twenty wheat genotypes, including two checks, Khaista and Wadan, were evaluated in RCBD under irrigated and rainfed environments for genetic variability, drought tolerance indices, and broad-sense heritability of various traits. Analysis of variance revealed highly significant variation among genotypes for spike length, biological yield, grain yield, and harvest index, while significant variations were observed for spikes m-2 , spikelets spike-1, and 1000-grain weight. Significant genotype × environment interaction was observed for all the studied traits. Different tolerance indices, like MP (mean productivity), GMP (geometric mean productivity), TOL (tolerance), SSI (stress susceptibility index), YI (yield index), YSI (yield stability index), and RDI (relative drought index) were estimated based on yield in irrigated and rainfed conditions. Under an irrigated environment, the highest yield was recorded for G-163 (5700.0 kg ha-1 ) and G-155 (5570.8 kg ha-1 ), while under a rainfed environment, Wadan (5161.1 kg ha-1 ) and G-163 (4852.8 kg ha-1 ) were the highest yielding genotypes. Under an irrigated environment, heritability was high for biological yield (0.71) and harvest index (0.77). Under a rainfed environment, heritability was high for grain yield (0.69) and harvest index (0.77), while low heritability was observed for spikelets spike-1 (0.22). GMP and MP had a positive, highly significant correlation with all the productive traits under both environments, thus it will be more useful for trait selection under rainfed and irrigated environments. YI was positive and highly significantly correlated with all yield contributing traits in rainfed conditions, thus YI would be a more reliable selection index in a rainfed environment. Wheat genotype G-163 showed the best performance under both tested conditions and can be recommended to be tested in further breeding programs for yield improvement.