Seasonal variation in genetic divergence of single-cut fodder sorghum: A multivariate analysis

Abstract

Limited knowledge of seasonal genetic divergence in single-cut fodder sorghum (Sorghum bicolor), particularly under summer conditions, hinders the identification of stable and superior parental lines. To address this gap, genetic diversity among 55 elite single-cut fodder sorghum genotypes was evaluated at CCS Haryana Agricultural University, Hisar, across the summer and kharif seasons of 2024 using 10 morphological, 8 biochemical, and 5 biotic stress-related traits. Multivariate analysis based on Mahalanobis’ D² statistics and modified Tocher’s clustering revealed substantial genetic variability, grouping genotypes into five clusters during summer and seven during kharif. High inter-cluster distances indicated significant genetic divergence, suggesting strong potential for heterotic hybridization. Cluster mean performance and divergence patterns identified key genotypes for targeted breeding, viz., CSV 19 SS for high biomass and micronutrient content (Zn, Fe), SH 2032 and SH 2136 for stable performance across seasons, and CSV 53F, CSV 44F, and HJ 1514 for high yield, better nutritional quality and lower HCN content. Genotype S 490, forming a singleton cluster in the kharif season, exhibited resistance against sooty stripe, shoot fly dead hearts and stem borer dead hearts, indicating its potential utility in resilience breeding. Seasonal comparison revealed greater genetic divergence under summer conditions, highlighting its importance for identifying highly discriminating genotypes under stress environments. Overall, the integration of yield, quality, and biotic stress traits across seasons provides a robust framework for selecting diverse and complementary parents. By elucidating genotype divergence across seasons, this study facilitates the selection of superior parental lines to develop climate-resilient, nutrient-rich fodder sorghum for sustainable livestock and bioenergy systems.