Effect of Supplemental Irrigation on Growth, Physio-biochemical and Yield Responses of Mothbean (Vigna aconitifolia L.) Genotypes under Rainfed Condition in Semi-arid Regions of Rajasthan

Mothbean cultivation in arid and semi-arid regions is practiced mainly under rainfed condition but increasing temperature and irregular rainfall pattern lead to drought conditions and substantially decreasing the yield. Supplemental irrigation at critical crop growth stage can play crucial role under water deficit situations in such regions. The field experiment was conducted to assess growth, physio-biochemical and yield responses of seven contrasting mothbean genotypes, viz. RMO-257, RMO-40, RMB-25, RMO-2251, CZM-45, RMO-435 and RMO-225 under rainfed (RF, drought condition) and supplemental irrigation (SI, irrigation applied at flowering stage i.e. 30 DAS) conditions. SI significantly improved plant growth attributes and water status which ultimately enhanced yield up to 35% as compared to RF condition. The water stress conditions significantly increased activities of antioxidative enzymes i.e. ascorbate peroxidase (APOX) and guaiacol peroxidase (GPOX) especially in tolerant genotypes. The correlation matrix and principal component analysis emphasized that there is positive relationship between growth attributes, water indices and yield of the genotypes whereas antioxidative enzymes showed negative relationship with yield.Among the genotypes studied, RMO-257, RMO-40 and RMB-25 performed well, whereas RMO-435 is more susceptible to drought conditions, as also demonstrated by a heat map of drought tolerance indices.