Characterization and Genetic Diversity of IIAM Doubled-Haploid Maize Inbred Lines for Agro-Morphological Traits

Genetic diversity within maize inbred populations is essential for sustaining genetic gain in breeding programmes. This study evaluated 280 maize inbred lines with two checks using an augmented block design (22 × 14). At harvest, 271 lines and two checks were analysed, with nine entries excluded due to poor survival. Using both descriptive (24) and quantitative (19) traits, significant variations were observed across many traits. Descriptive traits varied among the genotypes, as revealed by graphical analysis and correlation heatmaps. The likelihood ratio test (LRT) for lines showed significant differences for several quantitative traits with moderate–high heritability, while anthesis–silking interval, tassel length, ear position, ear aspect, bad husk cover, number of plants, and number of ears per plant exhibited low heritability. High genetic advance as a percentage of the mean was observed for grain yield, plant height, grain texture, number of plants, number of kernels, and grain weight per plant. Positive associations were observed among genotypic coefficient of variation, genetic advance, and heritability. Grain yield showed significant positive correlations with yield-related traits and morphological traits, but negative correlations with flowering traits. The first 10 principal components explained 86.17% of total variation, with flowering traits contributing most to variability in PC 1. Cluster analysis grouped genotypes into 10 clusters, with substantial genetic divergence within and between cluster groups. In conclusion, the study revealed considerable genetic diversity, supporting the selection of superior parents in breeding programmes and developing improved maize varieties to enhance productivity.