Trait Association and Path Coefficient Analysis Reveal Key Selection Traits for Grain Yield Improvement in Tropical Maize (Zea mays L.) Hybrids

Abstract

Grain yield in maize (Zea mays L.) is a complex quantitative trait governed by several interrelated morpho-physiological and yield-contributing characters. Understanding the relationships among these traits and their direct and indirect contributions to grain yield is essential for developing efficient selection strategies in hybrid breeding programmes. The present investigation was undertaken to estimate phenotypic and genotypic correlations and identify key yield-contributing traits influencing grain yield through correlation and path coefficient analyses in tropical maize hybrids. A total of 100 single-cross hybrids, developed from 20 genetically diverse inbred lines and five elite testers, were evaluated along with their parents and four commercial checks across eleven environments representing major maize-growing regions of Telangana, Karnataka and Maharashtra during the kharif season of 2025. Combined analysis of variance revealed highly significant effects of environments, genotypes and genotype × environment interactions for all the traits studied, indicating substantial genetic variability and differential genotype responses across environments. Phenotypic and genotypic correlation analyses revealed that grain yield was significantly and positively associated with ear girth, number of kernels per row, ear length, plant height, ear height, hundred-kernel weight and number of kernel rows per ear, whereas flowering traits exhibited negative associations with grain yield. Genotypic correlations were generally stronger than the corresponding phenotypic correlations, suggesting that these relationships were predominantly governed by genetic factors. Path coefficient analysis identified ear girth as the trait exerting the highest positive direct effect on grain yield at the phenotypic level. At the genotypic level, days to 50% silking and the number of kernels per row exerted the largest positive direct effects, followed by hundred-kernel weight and the number of kernel rows per ear. The low residual effects indicated that the selected traits adequately explained the variation in grain yield. Overall, the findings indicate that simultaneous selection for number of kernels per row, hundred-kernel weight, ear girth and number of kernel rows per ear would be an effective breeding strategy for developing high-yielding and widely adapted tropical maize hybrids.