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Uptake of NO 3 , NH 4 + , P, K ++ , Ca ++ and Mg ++ , as influenced by the stage of plant development and three NO 3 -:NH 4 + 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 NO 3 -and NH 4 + were supplied in equal concentrations, NO 3 -was absorbed more readily. Each increment in NH 4 + 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 NO 3 -. Results from this study suggest that NO 3 -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.

Calcium uptake by bell pepper (Capsicum annuum L. cv. 'California Wonder') varied by stage of plant development and N form supplied (NQ 3 -NH 4 + ratios: 1:0, 3:1, 1:1, 1:3, and 0:1) in a hydroponic study. Uptake of Ca ++ was highest at bloom and during fruit expansion, making the fruit development stage the highest demand period. Calcium uptake declined with each increasing increment of NH 4 + relative to NO 3 -supplied, although fruit yield was not significantly reduced until the ratio of NH 4 + to NO 3 -exceeded 50%. Tissue Ca ++ levels in the blossom-end of the fruit were reduced whenever NH 4 + was included with N supplied. Vegetative yield of plants followed the same trend as that observed for total fruit dry weights. Our results indicate that pepper yields are higher when NO 3 -is the predominant form of N. Also, these results strongly suggest that Ca ++ fertilizer applications should precede the bloom period and continue during fruit development to ensure adequate Ca ++ availability for fruit development.

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