Mungbean (Vigna radiata) Growth and Yield Response in Relation to Water Stress and Elevated Day/Night Temperature Conditions

Information regarding the relative importance of elevated day/night-time temperatures combined with water stress on mungbean yield is limited. This study aimed to investigate the yield response of mungbean cultivars to different water stress and temperature regimes under controlled glasshouse conditions. Two mungbean cultivars, Celera II-AU and Jade-AU, were grown and evaluated under four temperature regimes with and without water stress, each replicated 10 times in a randomized complete block design. The four temperature regimes were as follows: (i) HTHT: Plants were consistently exposed to high day/high night temperatures (35/25 &deg:C). (ii) LTHT: Plants experienced ambient day/ambient night temperatures (25/15 &deg:C) for the first 35 days, followed by the HTHT environment. (iii) LTLT: Plants were maintained at ambient day/ambient night temperatures (25/15 &deg:C) throughout the experiment. (iv) HTLT: Plants were subjected to high day/high night temperatures (35/25 &deg:C) for the initial 35 days, followed by the LTLT environment. Under water stress conditions, mungbean yield declined significantly in the HTHT environment by 57% for Jade-AU and 76% for Celera II-AU compared to the LTLT environment. The highest seed yield (10.2 g plant&minus:1 for Jade-AU and 11.4 g plant&minus:1 for Celera II-AU) for both cultivars was observed when grown without water stress in the LTLT environment. However, yield decreased substantially when plants experienced combined heat and water stress during the reproductive stage (HTHT and LTHT environments). Without water stress, mungbean yield under the HTHT environment decreased by 30% for Jade-AU and 60% for Celera II-AU compared to the LTLT environment. Surprisingly, no significant difference in response to water stress was observed between the two cultivars. Furthermore, when grown under no-water stress and HTHT environments, the yield of Celera II-AU was reduced by 37% compared to Jade-AU. Similarly, a comparable response was seen between cultivars under no-water stress and LTHT environment. The results indicated that water and heat stress negatively affected mungbean seed yield. Moreover, it was observed that Jade-AU outperformed Celera II-AU regarding seed yield under heat-stress conditions. In conclusion, this study suggests that adjusting sowing time and selecting suitable heat-tolerant cultivars, such as Jade-AU, could enhance mungbean yield under heat and water stress conditions. The results demonstrate substantial impacts on mungbean productivity from changing climatic and water stress conditions and these findings can be utilized for improving mungbean productivity in dryland regions.