PERFORMANCE OF CHLORIS-GAYANA AND BRACHIARIA-BRIZANTA INOCULATED WITHAZOSPIRILLUM

Two glasshouse experiments were carried out to study the effect of the inoculation with Azospirillum spp. on the performance of Panicum maxi mum and Brachiaria brizanta. Random block designs with five replicatio ns were used. In the first experiment the rhodes grass inoculated with the ICA A-1 strain increased (P < 0.05) dry matter yield (17.98 g/pla nt) compared to the control (14.77 g/plant). N yield did not vary betw een treatments. in the second experiment three bacteria strains with a nd without nitrogenous fertilization were tested. Brachiaria inoculati on with Sp 7 without fertilization (1.46 g/plant) increased (P < 0.001 ) yield compared to the unfertilized control (1.12 g/plant). Treatment s with unfertilized Sp 7 and ICA A-1 significantly increased the radic al system (0.57-0.61 g/plant) with respect to the control without nitr ogen (0.42 g/plant), but the fertilization did not stimulate the respo nse to inoculation. Bacterization did not increase P and Ca percentage s, but that of magnesium augmented. K content increased with the inocu lation and decreased with the fertilization of 20 kg N. In this study, modest increases in rhodes and brachiaria were attained with two Azos pirillum strains. Thus, further studies under field conditions would b e necessary and to carry out basic studies that will allow to clarify unknown aspects for increasing plant response.