Assessment of Genetic Diversity and Integrated Phenotypic-genotypic Evaluation of Maize (Zea mays L.) for Resistance to Fusarium Stalk Rot Caused by Fusarium verticillioides

Maize (Zea mays L.) is a globally significant cereal crop, but its production is severely affected by Fusarium stalk rot (Fusarium verticillioides), which reduces yield and grain quality. This study aimed to evaluate the genetic diversity and resistance of segregating maize populations derived from wide hybridization. A total of 54 F₂ lines (Kharif 2023) and 49 F2:3 lines (Rabi 2023-24) were assessed using an Alpha Lattice Design for agro-morphological and molecular characterization. Genetic variability was analyzed through Mahalanobis’ D² statistics, which classified genotypes into three distinct clusters based on key traits. To screen for resistance, a standardized toothpick inoculation method was employed in the pathological field, and disease severity was scored using a 1–9 scale. Molecular screening with 10 SSR markers identified resistant genotypes, with SSR93 and umc2059 proving effective in distinguishing resistance-associated alleles. Among 33 evaluated lines, six genotypes (2123859 X WS-5)^/4^-7, (2123426 X WS-5)^/6^-4, (2123401 X WS-5)^/10^-7, (2124008 X WS-1)^/5^-5, (2123792 X WS-1)^/10^-9, and (IC 0621166 X WS-5)^/5^-4 consistently exhibited resistance across both phenotypic and molecular evaluations. These findings highlight the genetic diversity within maize germplasm and provide valuable resources for breeding Fusarium stalk rot-resistant varieties. The identified resistant lines hold potential for use in maize improvement programs, ensuring sustainable production and enhanced disease resilience.