Water extraction patterns of mungbean (Vigna radiata) in diverse subtropical environments

Mungbean (Vigna radiata, L.) is an economically important food legume grown in tropics and subtropics and consumed by more than billion people in the world. There is limited information on water requirements of and irrigation strategies for mungbean. The objective of this study was to investigate water extraction patterns of mungbean grown under rainfed and irrigated conditions, in narrow or wide row spacing treatments, in two diverse environments. The two test environments i.e., Emerald Agricultural College (EAC) and Hermitage research station (HRS) in Queensland were characterised by contrasting seasonal average temperatures and vapour deficits (VPD). The amount of water extracted by irrigated and rainfed crops during early growth phase was lower but similar (excepting for HRS in 2015-16 season), compared to reproductive phase, where water extraction was significantly higher. The narrow row spacing treatment (0.25 m) extracted more water than 1.0 m row spacing treatment during early phases of crop growth only. Crops at HRS extracted greater amounts of water compared to EAC, with bulk of the water extraction occurring from the top 50 cm and 75 cm zones in rainfed and irrigated crops, respectively. However, at HRS, maximum water was extracted from the top 75 cm zone. Data pooled across environments revealed an exponentially negative relationship between seasonal vapour pressure deficit and the amount of water extracted. There was a significantly positive relationship between the total dry matter and yield, and the total water extracted. The findings of this study highlighted the variation in crop water requirements of mungbean at different phenophases, and the depth of water extraction. This information will be useful for developing irrigation management practices to optimise mungbean productivity