Abstract

HABERMANN, Eduardo et al. Phytotoxic Activity of Stem Bark and Leaves of Blepharocalyx salicifolius (Myrtaceae) on Weeds. Acta biol.Colomb. [online]. 2015, vol.20, n.1, pp.153-162. ISSN 0120-548X.  https://doi.org/10.15446/abc.v20n1.42756.

In this study, the phytotoxicity of extracts and fractions of stem bark (suber) and mature leaves of Blepharocalyx salicifolius Kuth O. Berg was evaluated on the initial growth of Echinochloa crus- galli L. P. Beauv. (barnyardgrass) and Euphorbia heterophylla L. (wild poinsettia). The extracts were obtained by exhaustive extraction and fractionation by the partition coefficient with organic solvents. Subsequently, the ethyl acetate extracts of bark and mature leaves and the hexane extract of bark were fractionated by column chromatography with solvents in increasing order of polarity. The extracts and fractions were evaluated on weed species at concentrations of 0,2, 0,4 and 0,8 mg.mL^-1, The positive control used was the commercial herbicide Sanson® at the same concentrations described and the negative control used was distilled water with DMSO (5 uL/mL). The ethyl acetate extracts of bark and mature leaves and hexane extract of bark showed the most pronounced inhibitory effects on the growth of the target species. Among the eight ethylic acetate leave's fractions, six inhibited the root growth of barnyardgrass at all concentrations tested and four fractions inhibited the root and shoot growth of wild poinsettia, at all concentrations tested. Of the six ethylic acetate bark's fractions, four showed phytotoxicity on root growth of barnyardgrass at all concentrations. The extracts and fractions of bark and mature leaves have given rise to anomalies in the target species. The results demonstrated a pronounced phytotoxic effect of the extracts and fractions of bark and mature leaves, providing subsidies for their use as natural herbicides.

Keywords : barnyardgrass; Myrtaceae; phytotoxicity; seedling growth; wild poinsettia.

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