Defining the critical period for yield determination in mungbean [Vigna radiata (L.) R. Wilczek]

Abstract

Context: Mungbean (Vigna radiata (L.) R. Wilczek) is a legume valued due to its high nutritional quality, rich in protein, essential amino acids and micronutrients. Mungbean also plays a key role in sustainable agriculture via nitrogen fixation and adaptability to diverse cropping systems. However, there is a noticeable gap in knowledge about the critical period of mungbean for seed yield determination.Objectives: This study aimed to (i) identify the critical period for seed yield determination in mungbean and (ii) determine the main important seed yield components influencing yield variation.Methods: Successive 14-day shading treatments were applied throughout the crop cycle at different points, from emergence to maturity, in field experiments conducted during the 2023 and 2024 growing seasons in Manhattan, Kansas, United States (US), with treatment timing expressed as thermal time (sum of degree-days above a base temperature of 7.5 ◦C) relative to flowering.Results: The critical period for yield determination was identified between 139 ◦C days before flowering (~7 days before flowering) and 427 ◦C days after flowering (~25 days after flowering), ranging from V8 to R5 crop growth stages (seventh trifoliate leaf to one pod on the main stem turning dark brown). Shade treatments reduced seed yield, with penalties ranging from 41 % to 68 %, and were mainly due to reductions in seed number per unit area, with limited compensation from increased seed weight. Pod number per unit area was the strongest determinant of final yield, while seeds per pod had a lesser effect.Conclusions: Defining the critical period for seed yield determination is essential for optimizing mungbean productivity through breeding and management strategies.