MICRO-ORGANISMOS PROMOTORES DO CRESCIMENTO VEGETAL PARA REDUÇÃO DA FERTILIZAÇÃO FOSFATADA EM SOJA E MILHO.

Abstract

With the expansion of agricultural frontiers and the migration of rural producers to the Cerrado, Brazil starts to break production records every agricultural year, mainly with soybean and corn crops. However, for this to happen, a great deal of research and technological development was necessary, especially in agricultural soil fertility management. The objective of this study was to evaluate the efficiency of different microbial consortia under different levels of phosphate fertilization in soybean and corn crops grown in the Cerrado. Two field trials (soybean and corn) were carried out in the 2023/24 summer harvest at the IF Goiano Experimental Area – Rio Verde Campus, GO. Both trials were randomized block designs, 3 x 5 factorial scheme (three levels of phosphate fertilization: 0, 50, and 100% of the recommended P dosage and five inoculation treatments: Azospirillum brasilense, Pseudomonas fluorescens, Azospirillum + Pseudomonas, Bacillus sp. + Paraburkholderia sp. and Priestia megaterium + Bacillus subtilis), with four replicates. Thirty-five days after emergence, in both trials, the following were evaluated: dry mass of the aerial part, roots, N and P contents in the aerial part and roots. For soybeans, the number and dry mass of nodules were also evaluated. At harvest, in both trials, the following were analyzed: mass of 1000 grains, N and P contents in the grains, and grain yield. The agronomic effectiveness of co-inoculation was proven to be a superior strategy, i.e., the combination of Priestia megaterium and Bacillus subtilis, or Bacillus and Paraburkholderia sp., or Azospirillum brasilense and Pseudomonas fluorescens is more favorable to soybean nutrition, growth, and productivity than isolated inoculation. Co-inoculation technologies (A. brasilense + P. fluorescens, Bacillus sp. + Paraburkholderia sp., and P. megaterium + B. subtilis) favor low-input systems as well as those aimed at optimizing the efficiency of conventional industrial phosphate fertilizers. The microbial isolates tested here as growth promoters acted synergistically and maximized the efficiency of phosphate fertilization in soybean crops. In corn cultivation, similarly, the co-inoculation of Priestia megaterium + Bacillus subtilis, or Bacillus sp. + Paraburkholderia sp., or even Azospirillum brasilense + Pseudomonas fluorescens enhanced corn productivity compared to the isolated inoculation of A. brasilense or P. fluorescens. Co-inoculation technologies (A. brasilense + P.fluorescens, Bacillus sp. + Paraburkholderia sp., and P. megaterium + B. subtilis) favored low-input systems as well as those aimed at optimizing the efficiency of conventional industrial phosphate fertilizers.