Abstract
The optimum dose of nitrogen (N) and phosphorus (P) for Withania somnifera was determined by utilizing graded levels of 0, 30, 45 and 60 kg ha−1 N and 0, 13, 26 and 40 kg ha−1 P in two separate simple randomized pot experiments. Soil-application of 45 kg N ha−1 and 26 kg P ha−1 proved the best dose for increasing shoot and root length, leaf area, fresh and dry weight of shoot and root, total chlorophyll and leaf-N, P, and potassium (K) content, nitrate reductase, and carbonic anhydrase activity, total alkaloid content, seed-yield per plant, root- yield per plant and berries per plant. While 30 kg N ha−1 proved best for root length, fresh and dry weights, as well as root-yield per plant. However, the effect of N and P fertilizers on carotenoid content, seeds per berry and 100-seed weight were insipid. Leaf- P remained unaffected by nitrogen application.