RESPONSES OF Brachiaria humidicola TO ARBUSCULAR MYCORRHIZAL INOCULATION AND SOURCES AND LEVELS OF PHOSPHATE FERTILIZATION

Abstract

The effects of four arbuscular mycorrhizal (AM) fungi species (Gigaspora margarita, Scutellosporaheterogama, Acaulospora muricata and Glomus mosséae) and two leveis of phosphorus (O and 22 kg of P/ha) and the inoculationof A. muricata and Araxá rock phosphate leveis (O, 44 and 88 kg of P/ha) on dry matter (DM) yield, and nitrogen (N) andphosphorus (P) contents and uptake by plants of Brachiaria humidicola were evaluated under greenhouse conditions, utilizinga clayey Yellow Latosol (Oxisol), previously sterilized. Independently of P levei, S. heterogama and G. margarita affectedsignificantly DM yields and P contents. Higher N concentrations were obtained with the inoculation of G. margarita and G.mosseae, in the absence of phosphate, wbereas in the presence of phosphate, plants inoculated with A. muricata presented thehighest N contents. Root colonization was increased by phosphate addition, mainly on the inoculations with G. margarita andS. heterogama The AM inoculation, alone or combined with rock phosphate fertilization, promoted significative incrementson DM yields and N and P contents and uptake. There were no significative effects of P leveis. Rock phosphate fertilizationimproved the efficiency of response to AM inoculation, and a synesgistic effect was observed. The root colànization was notaffected by rock phosphate fertilization.