Genetic diversity analysis of rust- resistant derived F₄ and F₅ 45 progenies of bread wheat by multivariate technique

The present study was planned to evaluate the extent of genetic diversity in yellow rust-resistant derived F₄ and F₅ generation progenies of two crosses of bread wheat i.e., WH 1105 x WH 711 and Raj 3765 x wH 711. Principal component analysis (PCA) indicated that the first five principal components explained over 80% of genetic variation among the traits in both the generations of both the crosses. Principal factor (PF) 1, 2 and 4 in F₄ generation, and PF-1, 2 and 3 in F₅ generation of cross-I showed high loading for grain yield/plant (0.878, 0.820), 100-grain weight (0.543,0.922), grain weight/ear (0.857, 0.655) and number of tillers/plant (0.931, 0.960). PF-1, 2 and 3 in F₄ generation, whereas PF-1 and 2 in F₅ generation of cross-II carried high score loading for number of spikelets/ear (0.925, 0.874), numbe r of tillers/plant (0.461, 0.895) and ear length (0.827, 0.566). So these PFs were regarded as grain yield factors and these traits contributing more to the diversity were considered as important in differentiating the genotypes. A total of 23 progenies derived from cross WH 1105 x WH 711 and 35 progenies derived from cross Raj 3765 x WH 711 were found better performing than the superior parents for different traits along with resistance to yellow rust. Wheat breeders can use these progeny lines as parents in wheat breeding programmes for developing high yielding wheat varieties with desirable stripe rust resistance gene combinations.