Glyphosate Stimulates the Accumulation of N-Compounds, Grain Yield and Seed Vigor in Glyphosate-Resistant Soybean

 Glyphosate-resistant (GR) soybean is widely used in agriculture, however, plants exposed to herbicide show physiological changes. This study investigated the effect of treatments with glyphosate on the metabolism of N compounds, crop yield and physiological quality of seeds in GR soybean. The plants were grown in field experiment, located in the city of Selvíria, MS, Brazil. Glyphosate was applied postemergence at V4 crop stage in a dose-response, including four rates (0; 360; 720 and 1440 g e. a. ha-1) with four replicates. Crop yield, physiological and biochemical features were determined. The results revealed previously unreported stimulant effects of glyphosate on GR soybean plants. Glyphosate changed the ureide shape in leaves, but did not change the concentration of total ureides, indicating maintenance of biological nitrogen fixation in plants exposed to herbicide. Amino acids concentration increased in plants submitted to higher doses. GR soybean showed higher crop yield and seed vigor with increased glyphosate doses. The results of this study indicate that glyphosate does not cause stress to the plant; however, it modulates a distinct response in plant development due to the protective gene inserted. This study can serve as a matrix for additional studies in order to seek clarification of responses of resistant/tolerant plants to glyphosate.