Associação de Azospirillum brasilense com doses de adubação nitrogenada no desempenho agronômico do milheto

Abstract

Inoculation with diazotrophic bacteria in grasses has been presented as a promising possibility to increase productivity and minimize the environmental risks generated by nitrogen fertilizers. Thus, this work aims to study the possibility of partially or totally replacing chemical fertilization, without compromising the production of millet forage, through the use of Azospirillum brasilense. A completely randomized design was used in a 2 x 5 factorial scheme (with and without Azospirillum brasilense and 5 doses of nitrogen- N applied after germination), with four replications, totaling 40 experimental units. The experimental units were vases with dimensions of 25cm x 15cm, containing 10 liters of soil. Inoculation was performed using the inoculant NoduGram L, which contains strains of Azospirillum brasilense Ab-V5 and Ab-V6 at a concentration of 2x10⁸ Colony Forming Units.mL-¹, at the recommended dose of 100 mL/ha-¹. 40g of pearl millet seeds were treated with 2 ml of the product. Forage production did not differ, even though there was a tendency to increase for doses of N. For leaf nitrogen, there was an effect both for doses of N and for inoculation, however, the inoculated treatments showed responses to leaf N lower than those not inoculated. Regarding the number of tillers and number of total leaves, an effect was presented only for doses of N. Based on these results, it is not possible to partially or fully replace chemical fertilization by inoculation with Azospirillum brasilense without compromising millet forage production.