NUTRIENT-UPTAKE AND YIELD OF SWEET-PEPPER AS AFFECTED BY STAGE OF DEVELOPMENT AND N-FORM

Uptake of NO3-, NH4+, P,K++, Ca++ and Mg++, as influenced by the stage of plant development and three NO3-:NH4+ ratios (1:0, 1:1, and 0:1), was determined for sweet pepper (Capsicum annuum L. cv. 'California Wonder'). Uptake was highest during fruit development and immediately after fruit harvest, indicating that fruit removal promotes nutrient uptake. When NO3- and NH4+ were supplied in equal concentrations, NO3- was absorbed more readily. Each increment in NH4+ decreased the uptake of K+, Ca++, and Mg++ by fruit tissue, while no significant effect on the N and P content of the fruit was observed. Ammonium nutrition reduced plant dry weight and fruit yield in comparison to NO3-. Results from this study suggest that NO3- is the preferred N form, and that fertilizer application should be scheduled according to specific physiological stages to maximize nutrient uptake. Nutrient content of vegetative tissue was not indicative of potential yield.