Allelopathy of aqueous extracts of Achyrocline satureioides on the germination of Bidens pilosa

Abstract

The effects of aqueous extracts on seed germination can be assessed through allelopathic activi-ty, which refers to the ability of certain secondary compounds produced by plants to interfere positively or negatively with the development of another. The aim of this study was to evaluate the effects of aqueous extracts of Achyrocline satureioides (Lam.) DC. on the germination of Bidens pilosa L. cypselas. The tests were carried out in a biochemical oxygen demand in-cubator at 26.5 ºC, using aqueous extracts obtained by infusion of dry inflorescences at concentrations of 0.5, 5.0, and 10 g/100 ml and distilled water (control). Five replicates of 100 cypselas each, totaling 500 cy-pselas per concentration, were used. After seven days of germination, the emerged seedlings were counted to calculate the germination percentage, the rootlet length were measured, and the data were analyzed. The analyzed extracts exerted allelopathic effects on the germination percentage of cypsela, but did not interfere with seedling growth. Aqueous extracts of A. satureioides inhibited the germination of B. pilosa cy-pselas at all concentrations, indicating the allelopathic ability of these extracts.