Genetic variability and evaluation of water-deficit stress tolerant of spring bread wheat genotypes using drought tolerance indices

Water deficit stress is one of the most important environmental factors that reduce grain yield in bread wheat. Despite the recent progress in breeding this plant, there is still a need to improve bread wheat cultivars that tolerate water stress in the country. In the current research, 100 genotypes of spring bread wheat during the years 2020–2021 and 2021–2022 in two conditions of non-stress and water deficit stress in the form of a simple 10x10 lattice square design at the beginning of flowering in Gachsaran Research Center located in the south of Iran. Eight quantitative indices of tolerance to water deficit were calculated. Principal component analysis (PCA), hierarchical cluster analysis (HCA), analysis of variance, and Pearson correlation were carried out in this study. According to the data, significant genotypic variation was seen among genotypes for both individual yield and drought indices. Geometric Mean Productivity (GMP) recorded the lowest coefficient of variation (CV) value with 10.6 %, while Tolerance Index (TOL) recorded the highest CV value with 45.4 %. The heritability of several of the indices is moderate to high; the Stress Susceptibility Index (SSI) has the greatest heritability at 0.96. Four distinct clusters were formed from the 100 genotypes. PC1 and PC2 make up 98.4 % of the total variance. Specifically, PC1 covers 68.9 %, while PC2 accounts for the remaining 29.5 %. These chosen genotypes will act as parent plants in breeding initiatives to create novel varieties resistant to drought.