Atividade herbicida de palhada e extrato de sorgo

Abstract

Resumo em língua estrangeira: The use of allelochemicals to replace synthetic herbicides is a potential reality that supports biorational and lower-cost agricultural production. The present study aims to evaluate and identify the potential herbicidal action of straw and aqueous extract of sorghum plants. The work was carried out in the experimental field at the State University of Goiás, Ipameri unit. The experiment was set up following a completely randomized design in a split-plot scheme with two plots and two subplots, with the main treatment allocated in the plots and constituted by the planting of grain sorghum (DOW 1G100) and common corn (SHS 7990 PRO3) in the off-season to straw formation and, in the subplots, the secondary treatments related to the presence and absence of weed control with the use of sorghum aqueous extract were placed. During the harvest period, soybeans were planted (FOCO Brasmax) in both plots. The weed control treatments constituted the subplots and consisted of the use of aqueous extract of sorghum leaves applied to weeds in the plots (ES1) and no weed control (ES0). Applications of sorghum aqueous extract occurred at three times throughout the soybean cycle at stages V3, R1 and R5. At 15 days after the last application, evaluations were performed on soybeans, and at the phenological stage R9, evaluations were performed on weeds. Sorghum straw reduced weed density by approximately 44% compared to soil covered with corn straw. The sorghum straw affected soybean yield components, however the post-emergence control with sorghum aqueous extract promoted weed control and allowed the soybean to develop without stress caused by the competition of productive resources such as water, light and nutrients. These results show the importance of sorgoleone as a bioherbicide, as it has an allelopathic effect on unwanted weeds. The sorghum extract exerts allelopathic action on weeds in soybean cultivation, at the same time the herbicidal effect is more pronounced in cultivation on sorghum straw.