The effect of slow-release fertilizer rates on growth and nutrient accumulation of 'Trifoliata' seedlings was evaluated in dibble tubes at a screen-protected nursery. The treatments comprised a control without fertilization and four rates (1.5, 3.0, 4.5, and 6.0 kg m-3) of slow-release fertilizer with 15% N, 10% P2O5, and 10% K2O, with total release of nutrients in 150 to 180 days at the temperature of 21ºC. Two standard treatments with soluble fertilizers, which differ one from the other by the omission or not of nitrogen (triple superphosphate, potassium sulfate and solutions of magnesium sulfate, micronutrients, and calcium chloride or calcium nitrate) were included. The treatments were disposed according to a randomized complete block design with four replications. The rates of N, P, K, and Mg used in the treatments with soluble fertilizers corresponded to the amounts supplied by the highest rate of slow-release fertilizer. Stem diameter, shoot dry matter yield and N, P, K, Mg and B accumulation of 'Trifoliata' seedlings increased with the rate of slow-release fertilizer. Soluble fertilizers causes greater stem diameter, and nitrogen and calcium accumulation in 'Trifoliata' rootstocks than slow-release fertilizer. Nitrogen deficiency limited growth and nutrient accumulation of 'Trifoliata' rootstock.
Poncirus trifoliata; mineral nutrition; propagation; protected environment
