Genetic diversity of diverse maize (Zea mays L.) germplasm for morphological traits using principal component and cluster analysis

Abstract

Maize (Zea mays L.) is one of the most economically and nutritionally significant cereal crops globally, yet its productivity in India remains considerably below the world average, necessitating systematic genetic improvement through the exploitation of available germplasm diversity. The present study was undertaken to morphologically characterise and assess the phenotypic diversity of 184 maize inbred lines derived from three distinct germplasm sources (176 inbred lines and 8 local checks) evaluated during the rabi season of 2024–25 at the Experimental Research Farm, Central Agricultural University, Manipur, India, using an Augmented Block Design. Data were recorded for 23 morphological and agronomic traits encompassing phenological, vegetative, yield component and grain quality characteristics. Analysis of variance revealed highly significant genotypic differences for most traits. Phenotypic coefficient of variation (PCV) exceeded genotypic coefficient of variation (GCV) for all traits, with high heritability estimates recorded for most traits, indicating the predominance of additive genetic effects and the effectiveness of direct selection. Phenotypic correlation analysis identified cob weight, kernels per row, rows per cob and test weight as the most strongly associated traits with grain yield per plant. Principal Component Analysis extracted eight significant components with eigenvalues greater than 1.0, cumulatively explaining 76.57 % of the total phenotypic variation, with shelling percentage, kernel traits, plant architectural traits and leaf morphology emerging as the primary contributors across successive components. Hierarchical cluster analysis using grouped the 176 inbred lines into two distinct clusters comprising 66 and 118 genotypes respectively, with germplasm distributed across both clusters. Genotypes V2225-36, V2189-226 and V2225-44 were identified as top-yielding selections, while 118955, LMC-11 and 118449 emerged as promising early maturing donors. The identified superior and genetically divergent genotypes are recommended as elite parents for future hybrid breeding programmes targeting the agro-climatic conditions of northeastern India.