Bidens sulphurea (Cav.) Sch. Bip is a species that was introduced in Brazil as an ornamental plant and it has become a weed, with a highly invasive capacity on crops of agricultural interest, probably due to its allelopathic effects, and it can suppress the growth of other weeds. This characteristic makes it a potential candidate for obtaining natural herbicides - allelochemicals - which, when isolated and characterized, can be used directly as herbicides or for the semi-synthesis of new compounds. In this sense, the present study aims to evaluate and characterize the allelopathic potential of the species B. sulphurea, as well as, extract, fractionate and isolate the phytochemical promoter of allelopathic effect. Allelopathic potential of B. sulphurea will be characterized by decomposition method and root exudation ("in vivo" plant). The extracts will be made with water and organic solvents separately, and will be applied in different concentrations on test plants (lettuce, tomato, radish, canary seed, onion and wheat) and target plants (signal-grass and guinea-grass), grown in a germination chamber to verify their allelopathic potential. The most active extracts will be divided according to proper techniques of chromatography and the fractions will be tested through the bioassays. The bioactive fractions will be analyzed by HPLC-UV-MS and nuclear magnetic resonance (NMR) to identify the substances in them. It will be performed tests for the comparison of means, and regression analysis with the data obtained.
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