APLICAÇÃO DE HERBICIDAS NO CONSÓRCIO ENTRE MILHO E Megathyrsus maximus cv. BRS QUÊNIA

Abstract

The forage species cultivation in intercropping systems with grain crops is a common practice in many regions of Brazil. This system aims to promote synergy between grain production or silage and forage production for animal grazing and/or haystack formation. However, it is essential to manage forages properly to avoid losses due to interspecific competition. Herbicide application is a technique that can reduce competition among intercropped crops. Therefore, this study aimed to evaluate the effect of applying herbicide doses in the management of Megathyrsus maximus cv. BRS Quênia (Syn. Panicum maximum) forage in intercropping with maize, considering its influence for weed control and on the biometric and productive variables of the forage and the maize. Three field experiments were carried out in a randomized block design with four replicates, and a different herbicide was evaluated in each of them, such as glyphosate, nicosulfuron, and tembotrione. The treatments consisted of applying six doses of glyphosate (0; 48; 96; 240; 480; 960 g a.i. ha-1), six doses of nicosulfurom (0; 2.5; 5; 12.5; 25; 50 g a.i. ha-1), and six doses of tembotriona (0; 3.78; 7.56; 18.9; 37.8; 75.6 g a.i. ha-1) herbicides, and maize treatment with no forage present. The B2360PW® maize hybrid was employed in all experiments. Results showed that there was a reduction in the weed density and in its dry mass in all three experiments, mainly due to the crop control imposed by the forage. It was clear that 260.87 g a.i. ha-1 and 25 g a.i. ha-1 doses of glyphosate and nicosulfuron herbicides, respectively, have the potential to be used in intercropping, as they were able to maintain the forage at an adequate height. The 50 g a.i. ha-1 dose of nicosulfuron caused phytointoxication in the evaluated maize hybrid. The tembotrione doses studied were not able to reduce the growth and development of BRS Quênia forage, but there was no influence on maize yield.