Integration of graphical and diallel analyses for identifying elite bread wheat genotypes for grain yield and its...

Improving grain yield and its components through a comprehensive understanding of genetic parameters continues to be a major challenge in wheat breeding, owing to the inherent complexity of simultaneously enhancing multiple agronomic traits. In the present study, the inheritance pattern of grain yield and its related traits in seven bread wheat (Triticum aestivum L.) genotypes, along with their F₁ progeny, was investigated using Hayman's numerical and graphical diallel analyses within the framework of a randomized complete block design with three replications. Morley-Jones analysis revealed significant differences (p < 0.05 or 0.01) for grain yield and most traits. Inheritance was predominantly governed by both additive and dominant gene effects, such that non-additive action, particularly overdominance, played a fundamental role in grain yield per plant (GYP) and most traits. The parental genotypes exhibited a higher frequency of dominant alleles compared to recessive alleles, and favorable alleles outnumbered unfavorable ones. The results of regression analysis showed the absence of non-allelic interactions for the traits plant height (PH), spike length (SL), spike weight (SW), number of grains per spike (NGS), spike grain weight (SGW), and number of spikelets per spike (NSP); while the presence of epistatic interactions was detected for number of tillers (NT), number of spikes (NS), and GYP. Based on low Wr + Vr, it is inferred that dominant alleles primarily control SD, SGW, SW, and SL. Also, the results of graphical analysis showed that the partial dominance pattern prevailed for PH, SL, NT, NS, and GYP. In contrast, overdominance was observed for SGW, SD, NGS, and SW, whereas the trait number of NSP exhibited a complete dominance pattern. Genotypes P6 and P7 carried more recessive alleles, whereas P2 and P3 had higher dominant allele frequencies, suggesting potential hybridization to develop superior lines. GGE biplot analysis identified P2 (Sakha 93) as the top performer for SD, NS, NT, and NSP, while P2, P3, and P5 combined high stability and grain yield, positioning them near the ideal genotype.