Genetic Diversity and Trait Association Analysis in Rice (Oryza sativa L.) Germplasm for Yield, Grain Quality, and Protein Content

Abstract

A panel of 147 genetically diverse rice genotypes was evaluated for grain yield, grain protein content (GPC), and key grain quality traits to elucidate the relationship between GPC, yield, and quality parameters. Grain protein content showed a significant positive association with head rice recovery (HRR; 0.24), suggesting the feasibility of identifying genotypes combining high protein content with superior milling quality. However, GPC exhibited significant negative correlations with gel consistency (GC; −0.33) and kernel length (KL; −0.20), along with a weak negative association with single plant yield (SPY; −0.12). Head rice recovery was negatively correlated with kernel breadth (KB; −0.39) and amylose content (AC; −0.22). Regression analysis revealed that GPC was predominantly influenced by GC, AC, HRR, and hulling percentage. Principal component analysis (PCA) indicated that four principal components accounted for approximately 72.0% of the total phenotypic variation. Hierarchical cluster analysis grouped the genotypes into ten distinct clusters, with genetic divergence largely contributed by length-to-breadth ratio (L:B), kernel length, gel consistency, and kernel breadth. Clusters III to X exhibited a high degree of heterogeneity, highlighting their potential utility in hybridization programs for generating desirable recombinants. Overall, the findings demonstrate that through systematic evaluation and well-planned breeding strategies, it is feasible to develop high-yielding, nutritionally enriched rice cultivars capable of contributing to both food and nutritional security.