EFFECT OF SELENIUM AS A CHEMICAL PROTECTOR ON THE SELECTIVITY OF HERBICIDES APPLIED IN POST EMERGENCY FROM Urochloa decumbens

Abstract

Some substances can be used as chemical protectors to increase the tolerance of crops to herbicides, including some micronutrients such as selenium. The use of herbicides in pastures has been increasingly used for weed management, this work aimed to evaluate selenium as a chemical protector in the selectivity of herbicides applied in post-emergence in U. decumbens. Three experiments were carried out in a greenhouse, in a 5x2 factorial scheme, five doses of herbicides and in the presence or not of selenium (Se) (25 g ha-1) applied via soil, in a completely randomized design, with five replications. The treatments are composed using the herbicides ametryn (0, 500, 1000, 1500 and 3000 g a.i. ha-1), ammonium-glufosinate (0, 75, 150, 300 and 600 g i.a. ha-1) and carfentrazone-ethyl (0, 5, 10, 20 and 40 g a.i. ha-1) and a treatment without herbicide application. They were evaluated at 3, 7, 14, 21 and 28 days after the application of treatments (DAA), phytointoxication and electron transport flow (ETR) and at 28 DAA plant height and shoot dry biomass. In general, there was an increase in plant phytoxication due to the doses of all herbicides studied. The application of Se, in turn, provided lower levels of phytointoxication, and consequently lower reductions in ETR, height and dry biomass when compared to plants not treated with Se. Thus, it is concluded that Se has potential use as a protector for these applied in post-emergence in U. decumbens.