The influence of phosphorus nutrition on the physiological response of moth bean genotypes to drought

Four genotypes of moth bean (Vigna aconitifolia Jacq. Marechal), including two early (RMO-257 and CZM-18) and two late flowering types (CAZRI moth-1 and Jawala) were grown at two levels of phosphorus (0 and 40 kg ha(-1)) and subjected to drought by withholding of water until wilting at the pre-flowering stage in a pot trial. Drought significantly decreased plant water potential, relative water content, rate of net photosynthesis, contents of chlorophyll, starch, soluble protein, and nitrate reductase activity in all genotypes. The adverse effects of drought were less pronounced in early than in late flowering genotypes. Phosphorus application significantly ameliorated the negative effects of drought on above parameters, particularly in the late genotypes. We conclude that P addition to moth bean may be justified even in low-rainfall years because of its ability to improve yield under water-limited conditions.