Assessment of Genetic Variability for Fodder Yield and Related Traits in Diverse Germplasm Panel of Maize (Zea mays L.)

Abstract

Enhancing biomass productivity in maize requires identifying traits that express strong and stable genetic variability across environments. This study quantified genetic variability, heritability and trait–yield relationships in a diverse CAAM (CIMMYT Asia Association Mapping) panel of maize by CIMMYT-Asia, Hyderabad, comprising 249 lines and 200 lines evaluated during two contrasting seasons i.e., Rabi 2023 and Kharif 2024 respectively, using an alpha-lattice design. Variance components, GCV, PCV, heritability (h²), genetic advance as percent of mean (GAM) and correlation coefficients were estimated to identify dependable selection indices for fodder improvement. Across both seasons, substantial genetic variability was recorded for major vegetative and ear traits. In Rabi, high GCV and PCV values were observed for leaf area (31.29%, 35.07%), fresh ear weight (37.18%, 37.44%), leaf:stem ratio (22.96%, 24.94%) and stem diameter (19.43%, 21.25%), respectively. These traits also exhibited strong additive genetic control, reflected by high heritability and GAM, particularly fresh ear weight (98.65%; GAM 76.60%), leaf width (95.75%; GAM 38.85%), plant height (93.31%; GAM 40.56%) and stem diameter (83.66%; GAM 40.03%), respectively. In Kharif, high variability evident from high GCV and PCV, persisted for ASI (53.34%, 70.18%), ears per plant (31.10%, 32.37%), fresh ear weight (37.72%, 38.04%) and stay-green (34.26%, 40.86%), respectively. This was also accompanied by very high heritability and GAM for ears per plant (92.32%; 64.06%), plant height (80.14%; GAM 46.66%), leaf area (76.61%; GAM 47.35%) and stem diameter (84.34%; GAM 44.00%). Green fodder yield showed moderate heritability in both seasons (33.37% in Rabi; 37.58% in Kharif), reflecting environmental influence. Correlation analysis revealed a consistent set of biomass-determinants. In Rabi, green fodder yield (GFY) correlated strongly with leaf area (r = 0.54), stem diameter (0.39), leaf number (0.39) and plant height (0.31). In Kharif, GFY again associated with stem diameter (0.53), plant height (0.29), ears per plant (0.25) and leaf area (0.20). Flowering traits showed weak or negative associations in both seasons. Collectively, stem diameter, leaf area, plant height, ears per plant and fresh ear weight emerge as stable, high-heritability, high-impact selection traits for developing high-biomass, climate-resilient fodder maize genotypes.