Santos, José Barbosa dosFerreira, Evander Alves Ferreira aKasuya, Maria Catarina M.Silva, Antonio Alberto daProcópio, Sergio de Oliveira2018-10-162018-10-162005-0102612194https://doi.org/10.1016/j.cropro.2004.10.007http://www.locus.ufv.br/handle/123456789/22257Application of glyphosate to soybean plants, resistant to this herbicide, may be harmful to Bradyrhizobium, the symbiotic bacterium. This study compared the effect of two glyphosate commercial formulations, ZappQi® and Roundup Transorb® with the standard N-(phosphonomethyl) glycine on the growth of four Bradyrhizobium strains under laboratory conditions. Commercial formulations were applied at a concentration of 43.2 μg L−1 of a.e. and the strains were inoculated in yeast extract mannitol (YEM) broth used with or without a mixture of aromatics amino acids (phenylalanine, tyrosine, tryptophan). Herbicide effect on the growth of the Bradyrhizobium strains was assessed by optical density reading in a spectrophotometer. Roundup Transorb® had the biggest effects, probably, because of the presence of ethylamine as a surfactant. Pure glyphosate had minimal effects on Bradyrhizobium strains when aromatics amino acids have been added to YEM broth. Glyphosate application as Roundup Transorb® in the initial stage of soybean development may affect the nodulation process by Bradyrhizobium.pdfengElsevier Ltd.AdjuvantAdjuvantAromatic amino acidsRhizobiumLaboratory bioassayArtigo