Glyphosate in post-emergence at Roundup Ready® soybean

Abstract

Generation of RR^® soybean genotypes allowed many farmers adopted the use of glyphosate in weed management in post-emergence in cerrado. However, information about the use of this technology on soybean crop growth in “cerrado” region is important in order to obtain desired yields. Thus, the objective of this study was to evaluate the effects of glyphosate application in post-emergence condition over agronomic characteristics and over RR soybean nodulation. The trial was conducted in randomized blocks experimental design in factorial scheme (3x4)+1 with three replications corresponding to three glyphosate doses (960; 1,920 and  2,880 g a.e ha^-1) associated to four application phenological stages of application (V₁, V₂, V₃ and V₁+V₄) plus a treatment without herbicide application (check). The following characteristics were evaluated: grain yield, mass of a thousand grain, plant height, phytointoxication, leaf closing, root dry matter and length, besides dry mass and nodules viability. Results revealed that the dose and stage of glyphosate application did not affect the nodulation, agronomic characteristics and grain yield. The highest percentage of phytointoxication and lowest leaf closing were observed at 2,880 g a.e. ha^-1 glyphosate dose sprayed on phenological stages V₁+V₄, without affecting nodulation and grain yield.