Efeito alelopático de óleos e extratos para controle de plantas daninhas

Abstract

The discovery of natural compounds with herbicidal potential for the control of harmful species appears as an alternative of adoption to the use of synthetic chemicals. Thus, allelopathy emerges as an important tool in the sustainable management of weeds. With that, the objective of this work was to evaluate the potential of essential oil and eucalyptus extracts, with the purpose of controlling weeds of bitter grass (Digitaria insularis) and black pick (Bidens pilosa). Different tests were conducted, with essential oil, aqueous extract and ethanolic eucalyptus extract, statistically compared, and in a factorial scheme. The experimental design was completely randomized with four replications. Six trials were conducted, using doses of essential oil, aqueous and ethanolic extract (0, 10, 30, and 60 g L-1) applied to the seeds or leaves of the target species, bitter grass (Digitaria insularis) and black pick (Bidens pilosa). The compounds were applied to the leaf area, with the help of a sprinkler, when the seedlings had two to three leaves. The germination tests, after sowing the species, the compounds were added according to treatment, in the germination role, in each “gerbox”. Among the interactions, it was identified that the eucalyptus essential oil did not promote effects when applied to the leaves of weeds, however, the application to the seeds had interaction. In the tests with extracts, both did not promote effects when applied to the leaves of weeds, but in applications in the seeds it reduced the germination percentage. The essential oil and the aqueous and ethanolic extracts of eucalyptus did not promote interference when foliar application was carried out, but interfered with germination when applied to the seeds of weeds.