© 2016, Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.Water deficit is one of the major factors affecting the growth and productivity field crops. This study was conducted to characterize four popularly genotypes, viz. SGC 16, TMB 37, SG 21-5, and Pratap, of green gram (Vigna radiata L.) on physiological, biochemical and morphological basis under water deficit at vegetative, flowering and pod filling stages. A substantial decrease in the mid-day leaf water potential (?L), net photosynthesis (PN), total soluble protein (TSP) and membrane stability index (MSI) were recorded under water deficit. However, the membrane lipid peroxidation (MDA), total free amino acid, and the activities of super oxide dismutase and catalase increased significantly (p = 0.05). Percentage reduction of grain yield, under water deficit, was the maximum in the genotype TMB 37 (50.05–63.80 %) indicating its sensitivity towards water deficit. In contrast, the genotype Pratap was the most tolerant to water deficit as it had the minimum reduction (20.76–34.87 %) in grain yield. Flowering was the most critical crop growth stage to water deficit. Among the studied parameters, ?L, PN, TSP, MSI and MDA were identified as the marker parameters for explaining the response mechanism of green gram genotypes to water deficit.