This experiment was carried out to evaluate the effects of nitrogen fertilization upon the morphogenetical and structural characteristics of Brachiaria decumbens under grazing. Four nitrogen rates (75, 150, 225 and 300 kg/ha.yr) were applied before the beginning of the experimental evaluations, which were performed during the Summer, Fall, Winter and Spring seasons. The randomized complete block design was used with two replications. Linear increases were observed for the leaf elongation rate, final leaf length, leaf area index, stem and leaf blade percentage. The percentage of dead material decreased with the nitrogen fertilization. On the other hand, N fertilization had no effect on the number of alive leaf, number of emerging leaves, total numbers of leaves, stem elongation rate and senescence rate. Leaf and stem elongation rates, number of alive leaf, final leaf length, leaf area index, leaf blade and stem percentages in the Brachiaria decumbens varied among seasons, lower values occurring in the winter.
nitrogen fertilization; leaf elongation; stem elongation; leaf length; morphological composition; season; leaf area index; numbers of leaves
