Doses subletais de glifosato em combinação com manganês foliar na produção de capim marandu

Abstract

The drift of the herbicide glyphosate can stimulate growth and/or productive yield in non-target plants, which characterizes a hormonal effect, with a momentary yellowing in new leaves, characteristic of nutritional deficiency. Thus, the objective of this work was to evaluate the hormonal effect of glyphosate application in Urochloa brizantha cv. Marandu. The produtive response, aerial (PMS ) and root (MSR), for forage was evaluated by foliar application of seven sublethal doses of equivalent acid (e.a.) to glyphosate (5.40, 10.80, 21.60, 43.20, 64, 80, 86.40 and 108.00 g e.a. ha-1) and control, in the absence and presence of manganese (1000 g ha-1), in the spray solution, in four sequential harvests, featuring a factorial scheme 8 x 2 x 4, with four repetitions. The sublethal doses of glyphosate with the addition of manganese to the spray solution reduced the herbicidal effect, with persistence of PMS during the experimental period (4 cuts). For doses without manganese added to the spray solution, there was a productive failure in the cuts 2, 3 and 4, at doses 86.40 and 108.00 g e.a. ha-1. The presence of manganese in the spray solution ensured a root dry mass superior to those without the addition of manganese, with an effect herbicide in doses equal to and above 43.60 g e.a. ha-1.