Glyphosate-resistant (RR) soybean crop areas have expanded every year. However, as a result of this expansion, the use of glyphosate has significantly increased, with the appearance of visual injuries in RR soybeans immediately after post-emergence application of the herbicide. Thus, two experiments were conducted in different years with different objectives. The first experiment aimed to evaluate the influence of glyphosate on photosynthetic variables and biomass production. The second experiment aimed to re-evaluate the same parameters affected in RR soybeans by glyphosate, as well as the use of various methods of amino acid application, as a form of a likely recovery of the soybean plants following these exogenous applications. The photosynthetic rate and SPAD index decreased as the glyphosate rate increased, with a pronounced decrease after a single herbicide application. Overall, due to a decrease in the photosynthetic rate and chlorophyll production, as well as to a likely immobilization of shoot nutrient concentration by glyphosate, a significant biomass decrease was verified in the treatments with glyphosate application. However, the use of exogenous amino acids may be a strategy to safeguard the undesirable effects of this herbicide on RR soybean.
photosynthesis; herbicide; chlorosis; Rhizobium
