Fusarium wilt constrains mungbean yield due to reduction in source availability

Mungbean [Vigna radiata (L.) R. Wilczek var. radiata] is an important source of plant protein for consumers and a high-value export crop for growers across Asia, Australia, and Africa. However, many commercial cultivars are highly vulnerable to biotic stresses, which rapidly reduces yield within the season. Fusarium oxysporum is a soil-borne pathogen that is a growing concern for mungbean growers globally. This pathogen causes Fusarium wilt by infecting the root system of the plant resulting in devastating yield reductions. To understand the impact of Fusarium on mungbean development and productivity and to identify tolerant genotypes, a panel of 23 diverse accessions were studied. Field trials conducted in 2016 and 2021 in Warwick, Queensland, Australia under rainfed conditions investigated the variation in phenology, canopy and yield component traits under disease and disease-free conditions. Analyses revealed a high degree of genetic variation for all traits. By comparing the performance of these traits across these two environments, we identified key traits that underpin yield under disease and disease-free conditions. Aboveground biomass components at 50% flowering were identified as significant drivers of yield development under disease-free conditions and when impacted by Fusarium resulted in up to 96% yield reduction. Additionally, eight genotypes were identified to be tolerant to Fusarium. These genotypes were found to display differing phenological and morphological behaviours, thereby demonstrating the potential to breed for tolerant lines with a range of diverse trait variations. The identification of tolerant genotypes that sustain yield under disease pressure may be exploited in crop improvement programs.