Vol. 9, Special Issue 7, Part L (2025)

The genetic divergence analysis of the association mapping panel using Mahalanobis D² statistics revealed substantial genetic variability among the 161 rice genotypes, which were categorized into 20 distinct clusters. Cluster III included the highest number of genotypes (41), followed by Cluster II with 34 genotypes. The highest intra-cluster distance was noted in Cluster XII (3408.90), indicating a high level of genetic variability within this group, followed by Clusters VIII, XIV, IV, III, II, and V, with the lowest observed in Cluster I (144.79). The greatest inter-cluster distance was recorded between Clusters XII and XIV (104161.70), followed by Clusters X and XIV (93870.59), emphasizing significant genetic divergence between these groups. The consistently higher inter-cluster distances compared to intra-cluster distances further underscore the wide genetic diversity across clusters. Considerable phenotypic variation was also observed for RLH% at flowering and associated yield traits. Clusters such as XX, I, IV, VIII, V, XIX, III, and XII exhibited lower RLH%, suggesting the presence of potential sheath blight (ShB) tolerant genotypes. Conversely, Cluster XVII recorded the highest RLH%, indicating susceptibility. Substantial differences among clusters were also noted for traits including days to 50% flowering, plant height, panicle number, panicle length, grain number, and test weight. These distinct and contrasting trait patterns across clusters provided valuable resources for breeding programs, QTL discovery, and allele mining aimed at enhancing ShB resistance and yield performance in rice.