Atividade alelopática de extratos de Caryocar brasiliense Camb. sobre a germinação, crescimento e aspectos bioquímicos e fisiológicos em Bidens pilosa, Glycine max e Zea mays

• Autor(a) principal: Oliva, Karla Martins Ferreira
• Data de Publicação: 2006
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/991
• topic: Pequi; Fotossíntese; Fluorescência; Estresse oxidativo; Caryocar brasiliense; Photosynthesis; Fluorescence; Oxidative Stress; Caryocar brasiliense; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::FISIOLOGIA DE PLANTAS CULTIVADAS

In order to investigate the allelopatic potential of methanolic extracts and fractions of Caryocar brasiliense a set of experiments, including germination, initial growth, biochemical and physiological evaluations were carried out on Bidens pilosa, Glycine max and Zea Mays. Chromatographic tests were made to identify the chemical substances in C. brasiliense. Leaves methanolic extracts (LME), steam (SME) and root (RME) of this specie were used for B. pilosa germination and initial growth tests, allowing a selection of the most effective inhibitory extract. Once the extract was selected (LME) its fragmentation was done using the following solvents: dichloromethane, ethyl acetate, methanol, ethyl acetate/methanol 1:1 and ethyl acetate/methanol 7:3. On the previous experiments, the LME concentrations used were 0, 1000, 2500 and 5000 ppm, while only the 0 and 5000 ppm of the fractions used. After the extract initial selection and its fragmentation, new germination and initial growth experiments were realized, this time using B. pilosa, G. max and Z. mays. The experiments results showed that the germination and the initial growth were only notable affected on B. pilosa and Z. mays. In order to select the most active fraction of LME, the same tests with the same species, were performed. Again, the obtained results showed that B. pilosa and Z. mays were the most sensitive species especially when the applied fraction was the dichloromethane fraction (DCM). G. max showed no significant responses to any the extract fractions. Afterwards new experiments were conducted using a different set of parameters to evaluate the effects of the fractions, respectively gas exchange, pigment concentration, a-chlorophyll fluorescence for the LME and enzymatic activity, lipid peroxidation and membrane permeability for the DCM. It was verified that the LME caused the most negative physiological effects on B. pilosa and Z. mays rather than on G. max. The B. pilosa and Z. mays plysiological traits modification lead in an oxidative stress in a such degree that the activity of antioxidant enzymes, as peroxidase, catalase and superoxide dismutase, were equally affected. The MDA production increased in B. pilosa and Z. mays probably due to the lipid peroxidation caused by the DCM fraction. The membrane permeability of these two species was also affected displaying a greater electrolyte leakage. On the other hand, no oxidative stress, lipid peroxidation or membrane permeability alterations were observed in G. max treated with the DCM fraction. Gas chromatography/mass spectroscopy reassures the essential class oils component substances presence in the dichloromethane fraction. The functional groups were confirmed by infrared spectroscopy modified from Fourier. The gathered results lead to the conclusion that C. brasiliense has substances methyl palmitate, acid palmitic, methyl elaidate, insaturated alcohol trans-phytol and methyl estearate. Those substances were able to interfere with the germination, initial growth, biochemical and physiological of B. pilosa and Z. mays. However, in this study, G. max showed tolerance to both LME and DCM fraction.