Mitigating Drought by Exogenous Potassium-mediated Improvements in Water Relation, Antioxidant Defense, Morpho-physiological and Biochemical Attributes of Black Gram [Vigna mungo (L.) Hepper]

Background: Globally, drought stress (DS) incidence in early development and grain-filling stages of crops like black gram has posed a serious constraint to the growth and yield of legume crops. To ensure the food and nutritional security of the rising human population, requisites developing eco-friendly, pro-farmers and cost-effective DS mitigation strategies for imparting yield sustainability to black gram. Methods: In this trial, treatments included control group entailing control (normal watering), water spray (WA, positive control), control+50 mg L-1 K2SO4, control +100 mg L-1 K2SO4, control +150 mg L-1 K2SO4, while drought treatment included drought stress (plant exposed to 15-20% by suspending water supply), water spray (WA, positive control), drought +50 mg L-1 K2SO4, drought +100 mg L-1 K2SO4 and drought +150 mg L-1 K2SO4. Result: The results exhibited that the DS seriously declined plant growth, relative water content and water potential by 24.2% and 39.3%, respectively, inducing higher levels of malondialdehyde (MDA) content and hydrogen peroxide (H2O2) concentration that reduced cell membrane stability, stomatal conductance and photosynthetic rate, than the control. However, the foliar applied K significantly improved plant growth, plant water status, gas exchange and photosynthetic performance, chlorophyll content and antioxidant enzyme activity. Exogenous application of K further reduced lipid peroxidation, cell membrane injury and hydrogen peroxide by 12.7, 17.6 and 8.70%, respectively.