A greenhouse experiment was carried out to evaluate the effects of nitrogen sources and rates on growth of rangpur lime seedlings in dibble tubes. The treatments comprised the combinations of two sources (calcium nitrate and urea) and four rates of nitrogen (0.15; 0.30; 0.45; and 0.60 g L-1), and an additional control treatment without N fertilization. The treatments were disposed according to a randomized complete block design as a 2 x 4 + 1 factorial arrangement with four replications. Nitrogen fertilizers (10 mL per dibble tube) were applied weekly during 15 weeks, starting at 56 days after seed germination. The data revealed effects of N rates on plant height, stem diameter and shoot dry matter yield. The effects of the N rates on these parameters were adjusted to quadratic regression models with maximum values corresponding to the rate of 0.37 g N L-1. The growth was reduced at rates higher than 0.37 g N L-1 of either calcium nitrate or urea. The effects of calcium nitrate and urea were different on root dry matter yield. For urea, root dry matter increased with the N rate, but for calcium nitrate the effect was described by a quadratic model, with maximum value corresponding to the rate of 0.35 g N L-1. Nitrogen, phosphorus, potassium, calcium, and magnesium accumulation in the shoot showed a direct relationship with dry matter yield.
citrus propagation; protected environment; nitrogen; Citrus limonia
