INFLUÊNCIA DE SISTEMAS DE CULTIVO NA EFICÁCIA DE HERBICIDAS NA PRODUÇÃO DO MILHO

Abstract

The intensive cultivation of maize has made the use of herbicides very frequent due to the productivity losses caused by weeds, as they promote negative effects on maize development with direct consequences on its production. The planting system with presence of straw in the soil has potential in reducing the infestation of species, which together with the chemical control are presented as a good management strategy in the corn crop. The objective of this work was to evaluate the efficacy of the herbicides "tembotrione+atrazine", "glyphosate+atrazine" and "glyphosate" in the post-emergence control of weeds in hybrid RB 9006 PRO3 and to analyze the impact of the applications on the indices of maize crop productivity, in a system with presence of straw in the soil and conventional planting. The experiments were carried out in an experimental station of Research Unit, in the Municipality of Uberlandia. A randomized complete block design was used, in a 2 x 5 factorial scheme, factor A: planting systems with presence of straw and conventional planting, and factor B: control without weeding, control with manual weeding, tembotrione+atrazine, glyphosate+atrazine, and glyphosate. The variables evaluated were control percentages at 14, 21, 28 and 35 days after application, shoot dry biomass (DB), ear insertion height at 60 days after application, a thousand grain mass (MMG) and yield. Data were analyzed through analysis of variance and the means compared by Tukey test at 5% significance. It was verified that in the system of planting with straw present the best results were obtained for the variable biomass of the aerial part (2,133 kg), height of the insertion of the spikes (95,40 cm), production (7,442 kg.ha-1) , a grain mass of 33 grams (337.5 g) and control at (14, 21, 28 and 35 days (81.5-100%), when compared to the conventional planting system) and the treatment "glyphosate + atrazine" of the other treatments, presenting 2,261 kg for biomass of 10 plants, 7,590 kg.ha-1 of production, and standing out in the system with planting with presence of straw with 357,5 g of a thousand grain mass and 100% of control at all times, thus evidencing an interesting alternative for weed management.