Trait Association Studies to Determine Selection Indices in F5 Segregating Populations of Rice (Oryza sativa L.)

The experiment consisted of 38 promising F5 breeding lines developed and evaluated for correlation coefficient, path coefficient and selection indices studies with four check varieties viz., NVSR-2435, Sardar, Lalkada Gold and GR-18 in RBD with three replications during kharif-2023 at RRRS, Vyara, Gujarat. Genotypic correlation analysis revealed that grain yield per plant appeared to be positively and significantly correlated with productive tillers per plant, plant height, panicle length, straw yield per plant and 100 grain weight, which suggested that these characters can be improved simultaneously towards higher grain yield per plant by direct selection. Genotypic path analysis revealed that positive and direct effects on grain yield per plant were exhibited by days to maturity, productive tillers per plant, panicle length, 100 grain weight and straw yield per plant. Among these traits, panicle length, productive tillers per plant, 100 grain weight and straw yield per plant exhibited direct effect along with highly significant and positive association with grain yield per plant. Therefore, selection for such traits may be considered as most important yield attributing characters. The negligible residual effect of 0.037 was observed in path analysis, indicates that the model explained large proportion of variance. Thirty-one selection indices were constructed in all possible combinations of grain yield per plant (X1) along with four components viz., productive tiller per plant (X2), panicle length (X3), 100 grain weight (X4) and straw yield per plant (X5) through equal weight method. Among all the selection indices, the relative efficiency (%) and expected genetic advance (GA) was noted maximum with four characters selection index (I1245) compared to grain yield per plant (I1).