Genetic Diversity of Tropical Maize (Zea mays L.) Inbred Lines Using Phenotypic Clustering

Abstract

Genetic diversity in maize is a valuable natural resource and plays a key role in hybrid breeding programs. The present study was conducted to assess the magnitude of genetic diversity among 107 tropical maize (Zea mays L.) inbred lines using phenotypic traits. Significant variability was observed for all the 11 traits. Days to 50% tasseling (DFT), days to 50% silking (DFS), plant height (PH), ear height (EH), cob length (CL), cob girth (CG), kernel rows per cob (KRPC), kernel per row (KPR), shelling percent (SP), seed weight (SW) and grain yield (GY). High heritability and genetic advance were observed for the traits Viz., DFT, DFS, CL, CG and KRPC, indicating their suitability for effective selection. In contrast, traits like GY, SP, and SW showed low heritability, suggesting stronger environmental influence and the need to exploit heterosis for yield improvement. Cluster analysis of inbred lines grouped them into seven distinct clusters, with considerable inter-cluster distances, particularly between Cluster II and V. Principal component analysis (PCA) revealed that the first five PCA components explained over 80% of the total variation. Potential genetically diverse genotypes Viz., CIMMYT-19, BHG-19, UASBM-69 and AHG-76-1 were identified by the PCA biplot as promising sources for hybridization. Overall, the results showed the importance of flowering and cob-related traits for selection and demonstrate the combined utility of cluster analysis and PCA in identifying diverse parental lines, thereby providing a strong foundation for hybrid development and genetic improvement of maize.