Associação entre nitrogênio e inoculação de forrageiras tropicais com bactérias promotoras de crescimento em plantas

Abstract

The use of microorganisms associated with forages appears as an alternative to reduce the use of chemical inputs, with notable environmental and economic benefits. Therefore, the objective was to evaluate the benefits of the association between nitrogen and tropical forages inoculated with growth promoting bacteria in plants. Two experiments were conducted under field conditions in the municipality of Araguaína-TO. Experiment 1 was conducted between the months of March 2016 and March 2017, with the forage marandu. The treatments were arranged in randomized blocks, in a 4x2 factorial arrangement, with four replications. Four nitrogen fertilizer doses (0.0, 12.5, 25.0 and 50.0 kg/ha N) were combined with two inoculation treatments (inoculated and non-inoculated), with evaluations carried out in three periods of the year (transition, dry and wet season). Experiment 2 occurred between the months of December 2017 and May 2018, with the forage mombasa. The treatments were arranged in randomized blocks, in a 5x2 factorial arrangement, with five doses of nitrogen fertilizer (0.0, 25.0, 50.0, 75.0 and 100.0 kg/ha of N) combined with two inoculation treatments (inoculated and uninoculated), in four replicates. Marandu grass plants inoculated with A. brasilense presented higher plant height, number of tillers and forage production than non - inoculated plants, regardless of the dose of N. The inoculation of the Marandu grass allowed a 20% reduction in nitrogen fertilization. For Mombasa grass, number of tillers and root production, inoculation efficiency varied according to the N dose supplied. However, the percentage of leaf N was higher for inoculated plants, regardless of the nitrogen fertilizer application. In conditions of absence of nitrogen fertilization, it was possible to increase forage production by 36% with the inoculation of the Mombasa grass.