Trait Association Analysis of Morphological and Yield Components in Rice (Oryza sativa L.)

Abstract

Rice (Oryza sativa L.) is a major staple and economic crop, and improving grain yield while maintaining grain quality remains a primary objective of rice breeding programs. This study evaluated the genetic variability and trait associations among 25 rice genotypes, comprising 22 advanced breeding lines and three commercial check varieties, under field conditions using a randomized complete block design with three replications. Fourteen agronomic, yield, and grain quality traits were recorded and analyzed using descriptive statistics, analysis of variance (ANOVA), correlation, and covariance analyses. ANOVA revealed highly significant (P ≤ 0.01) differences among genotypes for all traits except tillers per plant, which was significant at P ≤ 0.05, indicating substantial genetic variability within the germplasm. Grain yield exhibited wide variation (2524.80–4250.57 kg ha⁻¹), highlighting the presence of superior-performing genotypes. Correlation analysis showed a highly significant positive association between days to 50% flowering and days to maturity (r = 0.9992), whereas panicle length was negatively associated with grain yield (r = –0.4521). Grain length-to-breadth ratio was strongly and positively correlated with average grain length (r = 0.7798) but negatively correlated with grain breadth (r = –0.6161), confirming the slender grain characteristics of the evaluated germplasm. Covariance analysis further demonstrated considerable variability among agronomic and grain quality traits and revealed both positive and negative relationships among yield-contributing characters. The observed genetic variability and trait associations indicate that the evaluated rice genotypes constitute valuable breeding material for the development of high-yielding cultivars with desirable grain quality characteristics.