Morphogenic and structural traits of Brachiaria brizantha cv. Marandu under different nitrogen levels and residues heights

The objective of this study was to evaluate the rate of leaf appearance, leaf elongation rate, number of green leaves, length of blade and stem of Brachiaria brizantha cv. Marandu under different nitrogen levels and two residue heights. A randomized block design was used in a 4 x 2 factorial scheme, four doses of nitrogen (100, 200, 300 and 400 kg N ha-1 year-1) and two residue heights (5 and 15 cm). There was significant interaction between residue height and nitrogen levels for leaf appearance rate (P> 0.05) of signal grass, which was influenced negatively and linearly (P< 0.05) by the residue heights being observed an average reduction of 28.20% from lower to higher residue. There was no interaction (P> 0.05) between the levels of nitrogen x residue height on the number of green leaves. The dosage that provided the highest stalk in the residue height of 5 cm was of 271.5 kg N ha -1. An increase of 0.0745 cm tiller -1 day-1 for 1 kg of N ha -1 applied to height of 15 cm of residue was observed. Nitrogen fertilization contributes positively to growth and development of rates of appearance and leaf extension. The management of pasture of Brachiaria brizantha cv. Marandu with 5 cm of residue and fertilization with 100 kg N ha -1 provided better answer morphogenic traits.