Genetic variability and yield-determining traits in rice (Oryza sativa L.) genotypes under Bastar Plateau agro-climatic conditions

Rice (Oryza sativa L.) is a major staple crop worldwide and improving grain yield (GY) through the identification of superior genotypes and yield-contributing traits is essential for sustainable production. This study evaluated genetic variability, character association, path coefficients and genetic diversity among 64 lowland rice genotypes under transplanted conditions using a randomised complete block design (RCBD) with two replications. Significant variability was observed among the genotypes for yield and related traits. The highest GY values were recorded in AD 21303, TKR 35, MTU 1436, RP6811-8-1-3-2-1-1-B and OR 2573-3, indicating their potential for use in breeding programmes. High heritability coupled with high genetic advance (GA) was observed for kernel length-to-breadth ratio (KLB), grain length-to-breadth ratio (GLB), kernel breadth (KB) and related traits, suggesting the predominance of additive gene action. The genotypic coefficient of variation (GCV) was slightly lower than the phenotypic coefficient of variation (PCV), indicating environmental influence on trait expression. Grain yield showed significant positive correlations with days to 50 % flowering (DFF), days to maturity (DM), number of effective tillers per plant (NET), panicle length (PL), flag leaf length (FLL), number of grains per panicle (NGPP), test weight (TW), biological yield (BY) and harvest index (HI). Path coefficient analysis revealed that BY had the highest positive direct effect on GY, followed by HI, TW, flag leaf width (FLW), FLL, NGPP, PL, kernel length (KL) and KLB ratio. Cluster analysis grouped the genotypes into seven clusters, with Cluster III exhibiting superior mean performance for GY and associated traits. The DFF, DM and plant height (PH) contributed most to genetic divergence. The results indicate substantial genetic variability and identify BY, HI, TW and grain traits as important selection criteria for improving rice yield.