Aplicação foliar de Azospirillum brasilense isolada e em associação a adubação nitrogenada na cultura do milho

Abstract

ABSTRACT: Corn (Zea mays L.) is among the most cultivated species in Brazil, which produces it on a large scale. Nitrogen is one of the nutrients most required by corn. An alternative to reduce the use of nitrogen fertilizers is through the application of bacteria of the genus Azospirillum that carry out biological nitrogen fixation. Thus, the objective was to evaluate the effect of foliar application of Azospirillum brasilense, isolated and in association with nitrogen fertilization, on the microbiological activity of the soil, on the components of production and grain yield in maize. The experiment was carried out in randomized blocks, with four replications. The treatments were: nitrogen fertilization (66 kg ha-1) in coverage, foliar applications of Azospirillum brasilense Ab-V5 (0.5 L ha-1) and A. brasilense Ab-V5 and Ab-V6 (0.5 L ha-1) isolated and in association with mineral nitrogen (33 kg ha-1), applied in V3 and V6, and the control treatment. Microbiological evaluations of carbon in soil microbial biomass, soil microbial respiration, metabolic quotient, percentage of arbuscular mycorrhizal fungi (AMF) colonization, and AMF spore density were performed. In the crop, plant height, stem diameter, number of rows per ear, number of grains per row, mass of 100 grains and grain yield were evaluated. Inoculation with A. brasilense (treatment 3) was effective in increasing the chlorophyll content. Foliar application of Azospirillum brasilense in isolation provided higher values for stem diameter, 100-grain weight and grain yield, similar to mineral nitrogen fertilization.

Keywords: Nitrogen-binding bacteria. Inoculant. Nitrogen Supplementation.