Effects of foliar spray of KNO₃ (200ppm) on number of pod per plant, seed weight under moisture stress were studied in Black gram. Plants were subjected to mild, moderate and severe water stress which was created by withholding irrigation. The result indicates that moisture stress adversely affected dry matter and yield. Detrimental effect of water stress on yield were less in plant grown at 200ppm KNO_3. The yield increased 2-3 folds as compared to control in water deficit condition at 35DAS.The detrimental effects of water stress on Black gram were markedly less in K-fed plants. It is concluded that K-application helped plants in maintaining favourable internal tissue moisture and metabolic activities under water stress.