Genetic Divergence and Quantitative Trait Analysis of Yield-related Attributes in Rice (Oryza sativa L.) through Mahalanobis D² Analysis

Abstract

Aims: The aims of this study estimating the genetic components of variance, heritability and genetic advance and quantifying the genetic divergence among genotypes using D2 analysis to identify promising parents for strategic cross breeding programs. Study Design: The experiment was conducted in a randomized complete block design (RCBD). Place and Duration of Study: The experiment was conducted at the Norman E. Borlaug Crop Research Centre, G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India, during Kharif 2022-23. Methodology: The seedlings (25 days old) of sixty diverse genotypes were transplanted in RCBD with three replications. A plot size of 3m2/replication/genotype (3 rows each of 6.0 m length) maintained with row to row spacing of 20 cm. A single plant per hill was planted, maintaining hill to hill spacing of 15 cm. Results: The analysis of variance revealed highly significant differences among the genotypes for most of the traits, confirming considerable genetic variability. High estimates of broad-sense heritability and genetic advance as a percent of mean were observed for traits like plant height and number of tillers, suggesting that selection based on phenotype would be effective due to the prevalence of additive gene effects. Genetic divergence analysis using the D2 statistic grouped the genotypes into five clusters, with the maximum inter-cluster distance found between cluster I and cluster II (12.42). These two clusters are highly divergent and thus represent the ideal parental combination to maximize heterosis. Grain yield (17.46 %) and biological yield (14.43 %) were the largest contributors to the total genetic divergence and cluster II exhibited the highest mean value for key traits, including grain yield (13.11 g) and number of tillers (14.33). Conclusion: These findings underscore the importance of utilizing divergent parents from clusters I and II to develop high yielding and resilient rice varieties.