POTENCIAL DE USO DE HERBICIDAS E EFICIÊNCIA DO CONSÓRCIO ENTRE MILHO E FEIJÃO-GUANDU NA PRODUÇÃO E QUALIDADE DA SILAGEM

Abstract

One of the objectives with the consortium between grasses and legumes is to increase the protein content of the silage produced. In these systems, a possible competition can occur between the species that will be intercropped, making the correct planning of herbicides use of fundamental importance. Therefore, the objective of this work was to evaluate the selectivity of herbicides for pigeon pea intercropped with corn, and the effects of the intercropping on the development and yield of the intercropped crops, and on the nutritional quality of the silage produced. The design used was in randomized blocks with four replications, with the treatments arranged in a split-plot scheme, where the cropping systems were allocated in the plots and the types of weed control allocated in the sub-plots. The cropping systems were: maize monoculture, maize intercropped with pigeon pea variety IAC Fava Larga and maize intercropped with pigeon pea variety Bonamigo 2 Super N. The types of control used were: control, weeded plot; and the tank mixes of S-Metolachlor + Flumioxazin; S-Metolachlor + Saflufenacil; and S-Metolachlor + Mesotrione. The herbicides application took place in pre-emergence. At the time of ensiling, the plants were harvested when the corn grain had 1/3 of the grain in the milk line, the hard mealy grain stage. Then, aliquots of the material were removed for the ensilage in PVC tubes. The silos were sealed and stored in a covered area at room temperature for 56 days, when they were opened to evaluate the silage nutritional quality. The herbicides were effective in controlling weeds except for the species Acanthospermum hispidum (ACAHI) and Alternanthera tenella (ALTTE). The mixture of S-Metolachlor + Mesotrione was the one that obtained the lowest density and dry mass weeds production. There was no significant effect of cropping systems on the corn variables of plant height, first ear insertion height, dry and fresh mass yield, and grain yield. All herbicide mixtures caused phytointoxication in pigeonpea when compared to the control, but there was no significant effect of the types of control on the variables of plant height, final plant population and productivity of fresh and dry biomass of pigeonpea. The presence of pigeonpea in the silage increased CP, MM, EE, ADF, lignin, pH and N-NH3 contents and reduced DM, IVDMD, TDN and gas loss. All herbicide mixtures tested here showed potential use for pigeonpea. The intercropping of maize with pigeonpea did not affect the characteristics of development and yield of the maize crop but caused changes in the nutritional quality of the silage produced.