Evaluation of Intra- and Inter-line Genetic Diversity among Eight Drought-tolerant Maize Lines Using Agromorphological Descriptors in Côte d’Ivoire for Their Use in Breeding Programs

Abstract

Background: Maize is a major cereal crop in Côte d’Ivoire, but despite increasing production, yields remain below potential due to constraints such as low adoption of improved varieties, poor soil fertility management, and climate-induced drought stress. Therefore, developing and evaluating drought-tolerant maize lines is essential to improve productivity and ensure climate resilience. Aims: This study aimed to evaluate the intra- and inter-line genetic diversity of eight drought-tolerant maize lines derived from gamma-irradiated seeds. Study Design: A randomized complete block design (RCBD, Fisher design) with three replications was used. Place and Duration of Study: Université Jean Lorougnon Guédé, Daloa (Haut-Sassandra region, Côte d’Ivoire). Methodology: Eight lines, including two controls, were characterized using agromorphological descriptors related to phenology, growth, and yield. Data were analyzed using analysis of variance (ANOVA), principal component analysis (PCA), and hierarchical cluster analysis (HCA) based on Ward’s method. Results: Significant differences (P < 0.05) were observed among lines for several traits, particularly those related to growth and yield. Intra-line analysis revealed relative homogeneity, whereas inter-line variability enabled effective discrimination among genotypes. PCA, performed on eleven quantitative traits, identified two principal axes explaining 80.76 % of the total variance. Variables associated with growth and productivity contributed strongly to the structuring of the lines. HCA grouped the lines into four distinct clusters, highlighting genotypes with high agronomic potential and tolerance to water stress. Conclusion: The results indicate phenotypic homogeneity associated with exploitable genetic variability, likely induced by irradiation. This study confirms the relevance of mutagenesis as a tool for generating genetic variability and identifies promising lines for breeding programs under water-limited conditions.