SUPRESSÃO DE ESPÉCIES DE Brachiaria EM CONSÓRCIO COM MILHO SAFRINHA UTILIZANDO SUBDOSES DE GLIFOSATO

Abstract

The consortium of corn with forage is a viable alternative both for food enriched for livestock farming, and straw under no-tillage, in addition to the ability to suppress weeds, nutrition cycling, recovery of degraded areas and maintenance of quality physical-chemical soil. In this sense, it is important to research underdoses of the herbicide glyphosate for the management of grass in the consortium, to avoid losses of grain production and to make the consortium feasible in agricultural areas, extracting the maximum advantage of both crops. The objective of this work was to evaluate the use of the herbicide glyphosate in post-emergence in three species of brachiaria (Brachiaria brizantha cv. 'Marandu', Brachiaria ruziziensis and Brachiaria brizantha cv. BRS Piatã) intercropped in a second corn crop, as a way to suppress their excessive development and possible competitive potential with culture. The experimental design used was randomized blocks, in a 3x5 factorial scheme, with four replications. The application of five underdoses of the herbicide (0; 30; 60; 90 and 120 g p.c. ha-1) was considered, in which the zero dose represents the absence of the herbicide, in addition to another treatment (weeding plot), that is, maize without intercropping. Phytointoxication assessments of brachiaria plants were performed at 7, 14, 21 and 28 days after application. For the cultivation of corn, grain yield and dry mass was evaluated by harvesting the useful area of the plots. The best dose to slow the growth of forages without compromising their development is 30 g.p.c ha-1, with the exception of the piatã cultivar, which accepts the dose of 60 g.p.c ha-1. The forage that stood out the most in the consortium was U. ruziziensis. The productivity evaluations were more expressive for B. ruziziensis at a dose of 30 g p.c. ha-1 and for corn treatments without intercropping. The dry matter averages did not show significant correlation for the treatments.