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

Abstract

<p><strong>Background. </strong>The use of microorganisms in agriculture, such as <em>Bradyrhizobium japonicum</em> and <em>Azospirillum brasilense</em> and soybean cultivation together with nitrogen fertilization, may be interesting alternatives to increase crop yield. The soybean with the use of <em>Azospirillum brasilense</em>, together with <em>Bradyrhizobium</em> bacteria, in a current approach aimed at agricultural, economic, social and environmental sustainability. <strong>Objective</strong>. To evaluate the influence of the application of different doses of <em>Azospirillum</em> <em>brasilense</em> on co-inoculation with <em>Bradyrhizobium japonicum</em> in the soybean crop, in the first and third year of cultivation. <strong>Methodology.</strong> 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<sup>-1</sup> of seeds) of the commercial product Nitrogeo AZ<sup>®</sup>, composed of <em>Azospirillum brasilense</em>, with 4 replicates. For the standard inoculant the commercial product Nitrogeo Soja Turfa<sup>®</sup> was used <em>Bradyrhizobium japonicum</em>, with a dose of 3.2 g kg<sup>-1</sup> 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. <strong>Results.</strong> There was an increasing in both grain yield and thousand grains weight in the treatments with <em>Azospirillum brasilense</em>. 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. <strong>Conclusion. </strong>The use of these bacteria (<em>Azospirillum</em> with <em>Bradyrhizobium</em>) together contributes to increase productivity in the soybean crop.</p>