Structural and Production Characteristics of PiatãGrass Forage Submitted to Levels of Nitrogen

Piat&atilde grass (Brachiaria brizantha cv. Piat&atilde) is a tropical grass cultivating in pasture production system. The aim of this study was to evaluate the effects of nitrogen levels (0, 125, 250, 375 and 500 kg&middotN&middotha-1) on structural characteristics and forage production of Piat&atilde grass. The experiment comprised of twenty grass parcels arranged in randomised completely casualties design. This study was carried out between November of 2007 and April of 2008, with 175 experimental days. A quadratic effect (P &middotm-2 at a nitrogen dose of 357 kg&middotha-1. A quadratic effect (P &middotha-1&middotyear-1?for nitrogen levels of 411 and 384 kg&middotha-1, respectively. However, a considerable portion of forage production obtained by nitrogen addition occurred from stem production. The productions of green leaf blade dry matter, tiller density, leaf blade length and leaf blade index are all variables related to structural aspects and pasture quality, with all attaining their highest values at a mean nitrogen application level of 380 kg&middotha-1.