Morphogenesis and dynamics of tillering in a pasture of Panicum maximum Jacq. cv. IPR-86 Millennium under increasing doses of nitrogen

Abstract

It was evaluated the influence of the use of increasing doses of nitrogen (control = no N, 150, 300 and 450kg N/ha), in the morphogenetic characteristics of grass-Millennium, in grazing systems with intermittent stocking, from October 2006 to May 2007. The design was completely randomized, with split plot arrangement in time. The biomass accumulation rate of paddocks that received 300 and 450kg N/ha were similar: 104.30 and 110.40kg DM/ha/day, respectively. The rate of leaf appearance increased linearly, being 50% higher for the pasture with 450kg of N for that without fertilization. The phyllochron decreased with N rates increasing to the point of minimum of 310kg of N, and 37%, 50% and 40% lower for pasture in the 150, 300 and 450kg N, respectively, for that without fertilization. The rate of senescence of leaves was higher in spring and leaves long life were higher in autumn. Elongation rate was on average 60% higher for the treatments that received fertilizer. The pastures fertilized with 300 and 450kg of N were similar for variables rate of appearence tillers (1.1 tillers/100 tillers.perday) and rate of mortality tillers (0.8 and 0.9), respectively. Pastures not receiving nitrogen become inefficient drastically according to reduction of tissue flow, unlike those that receive fertilization being vigorous and productive for longer.