RESPONSE OF FORAGE SORGHUM (SORGHUM-BICOLOR CV SUDANENSE) TO AZOSPIRILLUM SPP INOCULATION

Three experiments (two under controlled conditions and one in the field) were carried out to study the influence of the inoculation of different Azospirillum spp (Sp7, ICA A-1 and CR-1) strains on the performance of forage sorghum sown in red ferrallitic soil. Random block designs with Five and four replications were used. In the glasshouse experiments the inoculation influenced green matter yields (1.35 to 154 g/plant) and dry matter (0.80 to 0.86 g/plant) which surpassed (P<0.005) the control treatment (0.77 and 0.52 g/plant, respectively). Sp7 strain inoculation significantly increased green matter yield (16.56 g/plant) with respect to the unfertilized control (14.04 g/plant). In the field experiment there were, in general, green matter and nitrogen yields higher than the control (9 to 14% and 28 to 42%, respectively), although not reaching statistical significance. A similar performance was shown in the dry matter yield with values of 22.6 to 23.2 t/ha for biofertilized treatments and 19 t/ha for the central. These responses indicate a favourable effect of inoculation, which justify further studies in this field.