Brassinosteroide e adubação nitrogenada no crescimento e estado nutricional de mudas de abacaxizeiro provenientes do seccionamento de caule

The objective of this study was to investigate the effect of nitrogen fertilization and an analogue of brassinosteroid in the growth and nutrition from the sectioning stem of the pineapple 'Smooth Cayenne'. The experiment was conducted in randomized block design in a 3x4 factorial design, were evaluated three doses of N (5, 10 and 15 g L-1), using urea as a source, and four doses of a brassinosteroid analogue (0; 0.5, 0.75 and 1.0 mg L-1) with four replications. Each plot was composed of 20 stem sections. At 270 days after planting the seedlings were harvested and evaluated in relation to the length, diameter, leaf number and leaf area. Then the seedlings were placed to dry in an oven at 70°C to obtain dry mass and nutritional analysis of leaf tissue which evaluated the levels of N, K, Ca, Mg, S, Fe, Cu, Zn and Mn. The analogue of brassinosteroid promoted increment in all the characteristics of growth of the pineapple seedling evaluated, and provide higher nitrogen content in top of seedlings. Nitrogen fertilization resulted in only slight increase in the length and diameter of the seedlings and did not affect the number of leaves, leaf area, dry weight and nutritional status of the seedlings.