Glyphosate and atrazine inhibit growth of Azospirillum brasilense, Bacillus subtilis, Bacillus thuringiensis, Chromobacterium subtsugae and Saccharopolyspora spinosa

Glyphosate and atrazine are two herbicides used worldwide to ensure high yields in different types of crops. Despite the importance of herbicides, their application may have negative effects on non-target organisms, including bacteria used in biological control and biological nitrogen fixation. Therefore, this research aimed to analyze the in vitro effect of glyphosate and atrazine on the growth of bacteria Azospirillum brasilense, Bacillus subtilis, Bacillus thuringiensis, Chromobacterium subtsugae, and Saccharopolyspora spinosa. The design used was completely randomized, and the doses of the herbicides evaluated were 1.0, 2.0, 3.0 and 4.0 L ha-1. The results showed that glyphosate and atrazine affected the development of the bacteria under study. Atrazine showed a lineal increasing effect between the doses used and inhibition of bacterial growth. Therefore, the dose of 4.0 L ha-1 of this herbicide was the one that showed the highest inhibition of bacteria, whereas glyphosate at a dose of 2.0 L ha-1 showed the highest inhibition of bacteria compared to doses of 1.0, 3.0 and 4.0 L ha-1.