Crescimento, rendimento de grãos e rentabilidade de soja (Glycine Max l. Merril) coinoculada com microrganismos promotores de crescimento de plantas.

Abstract

The nitrogen requirement of soybean can be supplied by the symbiosis with elite strains of Bradyrhizobium, applied as inoculant at sowing. Several studies have searched for enhancement of these benefits by the co-inoculation of soybean with other beneficial microorganisms. Additionally, the Amazon is recognized as a biome rich in microorganisms with potential benefits to plants. Given this, the hypothesis of this study was that the co-inoculation of soybean plants can be extended to other plantgrowth-promoting microorganisms, resulting in benefits to productivity, profitability, besides enabling the improvement of growth in soil with incorporated mining waste. Field and greenhouse studies were conducted during the years 2020 and 2021 in the municipalities of Paragominas and Belém, in the state of Pará, northern Brazil. Initially, experiments were conducted to evaluate the potential of using commercial products for soybean co-inoculation as an alternative to phosphate fertilization. Next, the objective was to enhance the use of co-inoculation using regionalized strains of beneficial microorganisms isolated from the Brazilian Amazon region. Finally, the ability of regionalized microorganisms in association with low amounts of red mud, a by-product of aluminum production was evaluated. Co-inoculation with commercial products based on strains of Bacillus and arbuscular mycorrhiza fungi promoted increased soybean yield and profitability. The use of regionalized strains (Trichoderma asperellum and Bacillus amyloliquefaciens) promoted an increase in root volume, yield, number of pods, reproductive branches, plant height and net profit, compared with standard inoculation, but did not affect gas exchange by the plants. As for the association of co-inoculation with red mud (RM), the interaction of the residue with the co-inoculation promoted changes in root architecture, increasing the percentage of fine roots (<1 mm) in length and volume. Co-inoculation of soy plants with Bradyrhizobium and strains of beneficial microorganisms, regionalized or not, provided increment in growth, nutrition, yield and profitability to soy plants. In addition to the importance of higher soybean productivity, co-inoculation may become a key-element to promote a more environmentally sustainable agriculture.