Phenotypic Diversity and Correlation Analysis of Morphological Traits in Rice (Oryza sativa L.)

Abstract

Sixty rice genotypes were evaluated during the Kharif season of 2023 at the Norman E. Borlaug Crop Research Centre (NEBCRC), G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, using an alpha-lattice design with two replications to quantify phenotypic diversity and examine associations among 15 morphological and yield-related traits. The traits comprised plant height, flag-leaf length, flag-leaf breadth, leaf area, days to 50% flowering, number of panicles per plant, panicle length, number of grains per panicle, grain yield, biological yield, harvest index, grain length, grain breadth, grain length/breadth ratio and test weight. Pearson correlation analysis revealed that grain yield was strongly and positively associated with harvest index (r = 0.81, P < 0.01) but negatively associated with biological yield (r = -0.35, P < 0.01). Biological yield was positively associated with days to 50% flowering (r = 0.79, P < 0.01), flag-leaf length (r = 0.69, P < 0.01), leaf area (r = 0.68, P < 0.01), grains per panicle (r = 0.36, P < 0.01), plant height (r = 0.27, P < 0.05) and panicle length (r = 0.27, P < 0.05). Standardised Euclidean-distance-based hierarchical analysis partitioned the genotypes into five clusters containing 19, 8, 14, 10 and 9 entries, respectively. The greatest inter-cluster distance occurred between Clusters II and IV (6.885), while the smallest occurred between Clusters I and II (4.826). Cluster V showed the largest within-cluster distance (4.713), indicating comparatively high heterogeneity. Genotypes belonging to the widely separated Clusters II and IV constitute useful parental pools, provided their trait means and agronomic performance are also complementary. The results demonstrate appreciable morphological differentiation and identify trait relationships relevant to selection for rice improvement.