Abstract
ABSTRACT: Allelopathy is the term used to define any process involving secondary metabolites produced by plants and microorganisms that influence growth and development of agrobiological systems. Currently, it is sought to find allelochemicals of interest and know how to apply them in bio-herbicides to combat weeds. In this study, the effects of the crude leaf extract and fractions of Machaerium hirtum (Vell.) Stellfeld were analyzed on Euphorbia heterophylla L. (wild poinsettia) and Ipomoea grandifolia (Dammer) O’Donell (morning glory), as well as the occurrence of morphoanatomical changes. For this, 0.04 g of the crude extract and fractions were solubilized and diluted (50 mL) to concentrations of 0.1, 0.2, 0.4, and 0.8 g L-1 (m/v). Initial growth tests were performed on Petri dishes containing two paper sheets and seedlings of weed species with the respective treatments, being maintained in a germination chamber for 48 hours at 25 oC. Distilled water was used as a control. Shoot and root length was assessed in the initial growth. The percentage of inhibition was calculated based on the values obtained in the initial growth bioassays. Morphologically altered wild poinsettia seedlings were fixed and sectioned transversely for anatomical analysis. The results indicated significant changes in length, being wild poinsettia seedlings more sensitive when compared to those of morning glory. Morphologically altered seedlings presented root necrosis as the most frequent symptom. Anatomically, parenchymatic cells of the hypocotyl and roots of wild poinsettia seedlings presented smaller and irregularly shaped cells when compared to the control, causing significant reductions in the measured parameters.
Highlights
Weeds cause damage to the environment due to their invasion of cultivated and natural areas, representing one of the main problems of world agriculture
They have in the composition elements that make them less toxic, but it is necessary to understand the mechanisms of action of these allelochemicals to properly understand the biochemical interactions that occur between plants in the natural environment (Duke et al, 2007; Duke, 2010)
There was no growth of wild poinsettia seedlings under Crude extract (CE) and FCl at concentrations of 0.2, 0.4, and 0.8 g L-1 (Table 1), which resulted in high inhibitory rates of 63 and 46% and 83 and 56% (CE and FCl, respectively), indicating FCl as the most inhibitory (Figures 1 and 2)
Summary
Article XIMENEZ, G.R.1* SANTIN, S.M.O.1 IGNOATO, M.C.1 SOUZA, L.A.1 PASTORINI, L.H.1. Parenchymatic cells of the hypocotyl and roots of wild poinsettia seedlings presented smaller and irregularly shaped cells when compared to the control, causing significant reductions in the measured parameters. Neste trabalho foram analisados os efeitos do extrato foliar bruto e das frações de Machaerium hirtum (Vell.) Stellfeld em duas espécies daninhas: Euphorbia heterophylla L. XIMENEZ, G.R. et al Phytotoxic potential of the crude extract and leaf fractions of Machaerium hirtum of the initial groth of. Contendo duas folhas de papel, e as plântulas das espécies daninhas com os tratamentos respectivos, mantidos em câmara de germinação por 48 horas a 25 oC; utilizou-se como controle dos testes somente água destilada. Os resultados indicaram alterações significativas no comprimento; as plântulas de leiteira foram mais sensíveis que as de corda-de-viola.
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