Unravelling genetic diversity in rice germplasm for yield and related traits under organic conditions in South India

It is challenging to obtain high yield and productivity while growing rice in organic conditions. This study aimed to identify diverse parental lines, bring desirable genes for yield and related traits and select a superior line derived from genetic segregation and recombination, particularly for organic conditions. During kharif 2023, a diverse panel of 72 rice germplasm accessions was evaluated using an alpha lattice (6 ×12) design and replicated thrice at the agriculture farm of Vellore Institute of Technology, Vellore. For all fourteen quantitative traits included in the study, the results demonstrated significant differences (p < 0.001) among genotypes. High phenotypic and genotypic coefficient of variation (PCV, GCV) were noted for hundred seed weight, number of grain per panicle, number of filled grains per panicle, number of tillers per plant and number of productive tillers per plant. The study also found high heritability (h2) coupled with high genetic advance per mean (GAM) for all traits, indicating additive gene action. Single plant yield showed a highly significant correlation with number of tillers per plant and number of productive tillers per plant, suggesting they could serve as direct selection criteria for yield improvement. Diversity analysis (D2) classified the 72 genotypes into seven distinct clusters, with cluster IV and VI identified as the most genetically diverse. Principal component analysis found that the first five PCs contributed to 78.26 % cumulative variation with eigen value greater than one. The traits that contribute maximum to divergence are panicle length, hundred seed weight, flag leaf length, plant height, number of grains per panicle and days to 50 % flowering. The selection of genotypes in cluster IV and VI based on specific traits could be utilized in future crop improvement initiatives, with a focus on cultivar development for organic conditions.