EFFICIENCY OF GLYPHOSATE COMPLEXED WITH COPPER COMPARED TO THE COMMERCIAL PRODUCT IN Brachiaria decumbens Stapf

Glyphosate, a non-selective herbicide with systemic action, is one of the most widely used substances in modern agriculture. With the objective of comparing the efficiency of glyphosate previously complexed with copper (Cu421) with that of the commercial product (Roundup WG®) and the purified substance (purified glyphosate) in controlling Brachiaria decumbens Stapf (signal grass), tests were conducted of the in vitro and in vivo activity of the enzymes 5-enolpyruvylshikimate-3-phosphate synthase (EPSPs) and phenylalanine ammonia lyase (PAL). The Cu421 complex significantly inhibited the EPSPs activity, as did the commercial product. In vivo test showed that treatments increased PAL activity more than double. The Cu421 complexed caused a substantial decline in the Falker chlorophyll index, as well as, the greatest reduction in the fresh mass yield and total protein concentration. In addition, the Cu 421 complexed application resulted in an increase in N-NO3- content in B. decumbens. The Cu421 complex had similar action as Roundup WG® and the purified glyphosate, indicating the possibility of using this complex to control weeds.