Time to flowering and flowering duration in mungbean are unrelated physiological traits with independent genetic controls

Abstract

Mungbean (Vigna radiata L.), a valuable sub-tropical grain legume, typically has a long, asynchronous flowering window, increasing vulnerability to abiotic stress and complicating harvest. To facilitate breeding, we extensively studied days to flowering (DTF) and the novel trait flowering duration (FD) in multi-environment trials. A diverse nested association mapping population was evaluated across four field experiments in Queensland, Australia (2022-2023). Extensive phenotypic variation was observed for DTF (35-70 days after sowing) and FD (20-60 days). Both traits displayed Genotype x Environment interactions, with FD showing stronger environmental interactions than DTF. No relationship was evident between DTF and FD across environments. Genome-wide association studies identified eight quantitative trait loci (QTL) for DTF and one for FD, with no overlapping QTL. The accumulation of early or late alleles at DTF QTL was associated with variations in flowering time. We have shown for the first time in mungbean that DTF and FD are independent traits with distinct genetic controls and environmental responses. This foundational understanding of mungbean flowering behaviour offers a mechanistic basis for developing varieties with optimized flowering patterns. Our findings provide crucial insights for future breeding programs, potentially enhancing mungbean adaptation and performance in diverse agricultural environments challenged by climate change.