Caracterização de perfilhos em pastos de capim-marandu diferidos com alturas e doses de nitrogênio variáveis

Abstract

This study was conducted in order to evaluate the structural characteristics of tillers in Brachiaria brizantha cv. Marandu under two sward heights (15 and 30 cm) and four nitrogen rates (control, 40, 80 and 120 kg ha-1) at the beginning of the deferral period. The experimental design was completely randomized with three replications and 4 x 2 factorial design. There was a linear increase in the number of vegetative tillers on the deferred pasture with 15 cm, with nitrogen fertilization. The length of the stem and the leaf blades in vegetative and reproductive tillers increased linearly with nitrogen in the deferred pastures with initial height of 15 and 30 cm. The weight of vegetative tillers was greater in the deferred pasture with 30 cm, compared to that of 15 cm, when pasture was fertilized with 0 and 40 kg/ha N. Nitrogen fertilization influenced positively and linearly the weight of vegetative tillers in deferred pastures with 15 and 30 cm, as well as the weight of reproductive tillers in deferred pastures with 30 cm. There was no effect of nitrogen fertilization on the live leaf blade:live stem ratio on either sward heights. The recommended management for the Brachiaria brizantha cv. Marandu pasture is 15 cm at the beginning of the deferral period. This pasture can be fertilized with variable nitrogen rates at the beginning of the deferral period, but doses above 80 kg/ha of N are not recommended.