Genetic variability and trait relationships were evaluated in 15 improved cultivars of Southern Thai indigenous rice (Oryza sativa L.). The study focused on grain yield and quality-related traits to reinforce rice breeding initiatives. Significant genetic variability was evident among the rice genotypes, with substantial genotypic and phenotypic coefficients of variation for the number of tillers and the number of ears, along with high heritability estimates for these traits. These indicate a robust genetic control and suitability for selection. Path coefficient analysis identified the number of tillers and the number of ears as primary contributors to seed weight per panicle. Protein content exhibited a complex relationship, receiving negative influences from seed weight per panicle and the number of seeds, suggesting their importance for improvement in grain yield. Correlation analysis revealed a considerable positive association between the number of tillers and the number of ears; however, a negative correlation between seed weight per panicle and protein content indicates a challenge in simultaneously improving both traits in rice. Principal component analysis confirmed seed weight per panicle and protein content were the primary drivers of the variability. The results will enable breeders to optimize grain yield and quality and develop high-yielding and nutritious rice cultivars for sustainable production.
Rice (O. sativa L.), improved cultivars, genetic variability, path analysis, correlation, yield-related traits, seed-quality traits
In rice (O. sativa L.), grain yield sustained direct influences from effective tillers and panicle weight, while significant variability in seed quality traits offers scope for further improvement. Promising genotypes, such as V14 with high protein, V10 (high lipid), and V15 with high amylose content, were successful in their identification as ideal candidates for targeted rice breeding programs.