Abstract

Lantana camara (L.) is considered one of the main weeds of agricultural crops, and allelochemicals produced by this species may be a source for the development of natural herbicides. In this study, phytotoxic effects of L. camara aqueous extracts on seed germination and seedling growth of Avena saliva (L.) were assessed. The experimental design was completely randomized, in a 2 x 5 factorial scheme, with treatments resulting from two assays, testing five concentrations of the extract (0 %, 2.5 %, 5.0 %, 7.5 % and 10 %; vv(-1)). During the seed germination, physiological (e.g., seed imbibition, germination and vigor) and biochemical (e.g., catalase, ascorbate peroxidase, praline, phenols, malondialdehyde and hydrogen peroxide) proprieties were evaluated. The leaf extracts of L. camara affected the response variables on A. saliva by reducing the germination speed index (phases I and II) and seed viability (phase III of germination), thus causing a solute leakage and increasing the production of reactive oxygen forms and, finally, lipid peroxidation. Extract concentrations above 2.5 % inhibit the growth of epicotyls. Therefore, the studied allelochemicals showed potential to be exploited in the development of natural herbicides.