Phosphorus fertilization and growth of buffel grass

Phosphorus (P) plays an important role in the growth of root system as well as the tillering grass, being fundamental to increase the productivity of these species. The aim of this study was to evaluate the development of buffel grass cultivars and establish critical values of P in plant and soil. The experimental set up was a 4 x 5 factorial scheme (four Cenchrus ciliaris cvs.: Biloela, Aridus, CPATSA 7754 and Pusa Giant, and five doses of [P.sub.2] [O.sub.5]-0, 30, 60, 90 and 120 kg [ha.sup.-1]) with four replications. After 90 days of cultivation, dry mass of shoot (DMS) and root (DMR) production and the P accumulation ([P.sub.acc]) were determined. Soil samples to determine the P content and determination of the critical level ([C.sub.ri][L.sub.ev]) were also collected. The cv. Biloela presented lower DMR and DMS production compared to the other cultivars. The cultivares Biloela, Pusa Giant and Aridus showed different critical levels of P in soil and plant, obtained in the greenhouse showing that they have different requirement of this nutrient for their growth. The cultivar CPATSA 7754 showed higher phosphorus requirement and did not permit to establish critical levels with doses used in the present study. Key words: critical level root system pasture O fosforo (P) desempenha papel importante no crescimento do sistema radicular, quanto no perfilhamento das gramineas, fundamental para o aumento da produtividade dessas especies. O objetivo deste trabalho foi avaliar o desenvolvimento de cultivares (cvs.) de capim-buffel e estabelecer os niveis criticos de P no solo e na planta. O experimento foi realizado em casa de vegetacao com arranjo experimental em esquema fatorial 4 x 5 (quatro cultivares de Cenchrus ciliaris: Biloela, Aridus, CPATSA 7754 e Pusa Giant e cinco doses de [P.sub.2][O.sub.5]-0, 30, 60, 90 e 120 kg [ha.sup.-1]) alem de quatro repeticoes. Apos 90 dias de cultivo foram determinadas a producao de fitomassa seca da parte aerea (MSPA) e a raiz (MSR) tal como o acumulo de P nesses tecidos. Coletaram-se amostras de solo para determinacao do teor de P e do seu nivel critico (NiCri). Em cultivares S Biloela, Pusa Giant and Aridus apresentaram diferentes niveis criticos de P no solo e na planta obtido na estufa demonstrando que a mesma apresentou exigencia diferenciada deste nutriente para seu crescimento. A cultivar CPATSA 7754 demonstrou maior exigencia em fosforo nao permitindo estabelecer os niveis criticos com as doses utilizadas no presente