POST-EMERGENCE APPLICATION OF GLYPHOSATE ON TRANSGENIC SOYBEAN GROWN IN THE CERRADO ABSTRACT

Abstract

The experiment was installed on a transgenic soybean field (Glycine max (L.) Merrill), variety Soy 8888-RR, planted on January 11, 1999. One glyphosate application at 1.2 kg/L was performed before seeding, which was carried out seven days after that management practice, in the no-till system. The products were applied in the entire area of the plot, using a carbon dioxide (CO2) precision sprayer. Treatments consisted of: glyphosate at 0.48; 0.72; 0.96; 1.20 and 1.44 kg/ha, applied 31 days after emergence (DAE); glyphosate at 0.72 kg/ha 22 DAE and at 0.48 kg/ha applied 42 DAE; glyphosate at 0.96 kg/ha applied 22 DAE and at 0.72 kg/ha applied 42 DAE; chlorimuron-ethyl + lactofen at 0.01 + 0,072 kg/ha, respectively, applied 31 DAE, plus hand-weeded and unweeded controls. The evaluated parameters consisted of apparent phytotoxicity at 15, 20, 42 and 51 days after treatment application (DAA), plant height and agronomic efficiency at 20 and 51 DAA, and grain yield. From the results obtained, it can be seen that glyphosate at the employed formulation, regardless of the concentration used, showed a very slight apparent phytotoxicity effect on the soybean plants, and was efficient in controlling the existing weeds with a single or with two sequential applications.