CO-INOCULATION WITH Azospirillum brasilense AND Bradyrhizobium japonicum IN SOYBEAN IN THE FIRST AND THIRD YEAR OF CULTIVATION

Abstract

Background. The use of microorganisms in agriculture, such as Bradyrhizobium japonicum and Azospirillum brasilense and soybean cultivation together with nitrogen fertilization, may be interesting alternatives to increase crop yield. The soybean with the use of Azospirillum brasilense, together with Bradyrhizobium bacteria, in a current approach aimed at agricultural, economic, social and environmental sustainability. Objective. To evaluate the influence of the application of different doses of Azospirillum brasilense on co-inoculation with Bradyrhizobium japonicum in the soybean crop, in the first and third year of cultivation. Methodology. The experiment was carried out in the municipality of Alta Floresta - MT, Brazil, in the harvest of 2016/2017. The treatments consisted of the combination of four doses (0, 2, 4, 8 mL kg-1 of seeds) of the commercial product Nitrogeo AZ®, composed of Azospirillum brasilense, with 4 replicates. For the standard inoculant the commercial product Nitrogeo Soja Turfa® was used Bradyrhizobium japonicum, with a dose of 3.2 g kg-1 of seeds. Height of first pod insertion, plant height, number of pods per plant, mass of one thousand grains, productivity and leaf content of nitrogen were analyzed. Results. There was an increasing in both grain yield and thousand grains weight in the treatments with Azospirillum brasilense. Higher plants with a higher number of pods were found in the area of the 3rd year of cultivation, compared to the area of the 1st year, however, the co-inoculant doses did not influence this variable. The highest grain yield was obtained with the use of 338 mL of commercial product per 50 kg of seeds. Conclusion. The use of these bacteria (Azospirillum with Bradyrhizobium) together contributes to increase productivity in the soybean crop.