IMPACTO DO HERBICIDA GLIFOSATO E DO METAL PESADO CÁDMIO SOBRE A VITALIDADE E FISIOLOGIA DOS LÍQUENS Parmotrema tinctorum (Nyl.) Hale e Usnea barbata (L.) F.H.Wigg.

Abstract

Lichens are very sensitive to environmental changes and due to their morphological characteristics, they are considered excellent bioindicators of environmental pollution. However, few studies have associated lichens with biomonitoring of agricultural pollutants. This work aimed to evaluate physiological changes caused by different concentrations of the herbicide glyphosate and heavy metal cadmium to two lichen species commonly found in Cerrado fragments, Parmotrema tinctorium and Usnea barbata. The purpose of the project is to identify the most sensitive biomarkers in both species, to generate perspective for their use in the biomonitoring of the agricultural pollutant dispersion. Cell viability, photosynthetic pigment levels, chlorophyll fluorescence and antioxidant metabolism were evaluated. In the treatment with glyphosate, it was observed in Parmotrema tinctorium and Usnea barbata low degradation of pigments, reduction in the average number of algal cells, significant changes in the values of chlorophyll fluorescence and in the activity of antioxidant enzymes, for the species treated with glyphosate, cell viability, chlorophyll fluorescence and antioxidant enzyme activity were the most promising biomarkers of herbicide action. In the treatment with cadmium Parmotrema tinctorium and Usnea barbata also showed sensitivity to the metal in relation to the vitality of algal cells and activity of antioxidant enzymes, low degradation of the pigments was observed and there were no changes in any parameter evaluated in the photochemical activity in the two species, thus, the viability of algal cells and the activity of antioxidant enzymes are the most sensitive biomarkers to the cadmium action.