The Influence of Nitrogen and Phosphorus on Vegetative Growth, Yield Components and Yield of Watermelon

Two field experiments were undertaken to evaluate the effects of nitrogen and phosphorus on vegetative growth, yield components and yield of watermelon. The treatments were five levels of nitrogen (0, 50, 100, 150 and 200 kg/ha) and four levels of phosphorus (0, 25, 50 and 75 kg/ha). The results showed that there were no interactions between nitrogen (N) and phosphorus (P) treatments on all the dependent variables determined. With application of 50, 100 and 150 kg N/ha watermelon plants had significantly (P = .05) increased vegetative growth, yield components and fruit yield of watermelon compared to plants in which N was not applied. Application of N above 150 kg/ha decreased vegetative growth, yield components and fruit yield of watermelon. Application of 25 and 50 kg P/ha to watermelon plants increased vegetative growth, yield components and fruit yield of watermelon compared to plants in which P was not applied. Application of 75 kg P/ha had no significant (P = .05) effect on vegetative growth, yield components and fruit yield of watermelon. The positive response of watermelon plants to N and P was attributed to the role of N and P on growth, development and efficient utilization of carbohydrates to form protoplasm and more cells, and the increase in dry matter. The authors concluded that in order to optimize watermelon growth, yield components and fruit yield, N and P should be applied at 150 and 50 kg/ha, respectively.