PENGARUH DEFOLIASI DAN LEVEL PUPUK NITROGEN TERHADAP PERFORMANS RUMPUT Brachiaria humidicola (Rendle) Schweick cv. Tully

DEFOLIATION EFFECT OF NITROGEN FERTILIZER AND LEVEL OF GRASS PERFORMANCE Brachiaria humidicola (Rendle) Schweick cv. Tully Brachiaria humidicola potential to develop since this species palatable as fed, able to suppressed weeds, persistent under heavy grazing and tolerant on dried environment. This species could produced chemical substance brachialactone as biological nitrification inhibitor, released in root rhizosphere automatically when defoliation occurred, and could increase the efficiency of nitrogen utilization in the field. The aimed of this experiment was to study the effect of defoliation and level of nitrogen fertilizer on the performance of B. humidicola. This experiment has been conducted at experimental station of Balai Pengkajian Technology Pertanian (BPTP) at Pandu, North Minahasa Regency, North Sulawesi. Treatments consists of defoliation as factor A (a1 = defoliated, a2 = non defoliated) and level of nitrogen as factor B (b1 = 0 gram, b2 = 40 gram, b3 = 80 gram and b4 = 160 gram N/plot). Treatments were placed as factorial arrangement based on Randomized Block Design with three blocks as replication. The result show that interaction of a1b1 give total phyllochron significant (P<0,05) higher than other interaction. Defolation (a1) effect significantly (P<0,05) higher than non defolation (a2) on number of tiller. There is non significant effect of both interaction and N fertilizer on shoot/root ratio on the orther hand defolation effect significantly (P<0,05) on shoot/root ratio. Based on this result it can be concluded that : (1). Defoliation increased total number of phyllochron, tiller and suport root defelopment of B. humidicola; (2). The needs of nitrogen was higher to produced tiller than phyllochron. Key Words : Defoliation, Nitrogen, Performance, humidicola