ABSTRACT
Glyphosate is a herbicide commonly used in agriculture for weed control. Current agricultural production demands vast amounts of this product, which are applied by ground or aerial spraying. The concomitant aerial currents promote glyphosate drift to vegetated or urban areas. In this context, we hypothesized that the lichens, Parmotrema tinctorum and Usnea barbata, could be sensitive to the action of glyphosate and therefore be used to bio-indicate the presence of this herbicide in areas affected by drift. Since living organisms respond in different ways to the action of herbicides, our interest was also to indicate biological markers responsive to the action of glyphosate, through concentrations and exposure times of the thallus, besides identifying the most sensitive species. We evaluated the effect of different concentrations (0.0, 4.8, 9.6, and 19.2 mg L-1) and exposure times (24, 48, and 72 hours) to glyphosate on the morphoanatomy, photobiont vitality, photosynthetic efficiency, and oxidative metabolism of the thalli. We found that the lichens, P. tinctorum and U. barbata, respond to glyphosate stress, with prospects for use in the biomonitoring of pollutant dispersal from plantation areas. When using P. tinctorum as a bioindicator, lichen morphoanatomy, photobiont vitality, and photosynthetic pigment concentration were efficient biomarkers for the effect of concentration and exposure time. For U. barbata, the lichenic morphoanatomy and the activity of SOD and APX enzymes were essential tools to indicate the herbicide action. Parmotrema tinctotum, however, was characterized as more sensitive in bio-indicating the presence of this herbicide to diagnose the air quality in urban areas or vegetation sectors adjacent to agricultural environments.
Subject(s)
Herbicides , Lichens , Usnea , Biomarkers , Herbicides/toxicity , GlyphosateABSTRACT
Glyphosate is a herbicide commonly used in agriculture for weed control. Current agricultural production demands vast amounts of this product, which are applied by ground or aerial spraying. The concomitant aerial currents promote glyphosate drift to vegetated or urban areas. In this context, we hypothesized that the lichens, Parmotrema tinctorum and Usnea barbata, could be sensitive to the action of glyphosate and therefore be used to bio-indicate the presence of this herbicide in areas affected by drift. Since living organisms respond in different ways to the action of herbicides, our interest was also to indicate biological markers responsive to the action of glyphosate, through concentrations and exposure times of the thallus, besides identifying the most sensitive species. We evaluated the effect of different concentrations (0.0, 4.8, 9.6, and 19.2 mg L-1) and exposure times (24, 48, and 72 hours) to glyphosate on the morphoanatomy, photobiont vitality, photosynthetic efficiency, and oxidative metabolism of the thalli. We found that the lichens, P. tinctorum and U. barbata, respond to glyphosate stress, with prospects for use in the biomonitoring of pollutant dispersal from plantation areas. When using P. tinctorum as a bioindicator, lichen morphoanatomy, photobiont vitality, and photosynthetic pigment concentration were efficient biomarkers for the effect of concentration and exposure time. For U. barbata, the lichenic morphoanatomy and the activity of SOD and APX enzymes were essential tools to indicate the herbicide action. Parmotrema tinctotum, however, was characterized as more sensitive in bio-indicating the presence of this herbicide to diagnose the air quality in urban areas or vegetation sectors adjacent to agricultural environments.
O glifosato é um herbicida comumente utilizado na agricultura para o controle de ervas daninhas, contudo, a produção agrícola atual demanda quantidades gigantescas deste produto, que são aplicadas por pulverizações terrestres ou aéreas, que acompanhadas de correntes aéreas, promovem a deriva do glifosato para áreas vegetacionais ou urbanas. Neste contexto, nós levantamos a hipótese de que os líquens Parmotrema tinctorum e Usnea barbata pudessem ser sensíveis à ação do glifosato e, portanto, bioindicar a presença deste herbicida em áreas afetadas por deriva. Como os organismos vivos respondem de diferentes formas à ação dos herbicidas, nosso interesse foi também de indicar marcadores biológicos responsivos à ação do glifosato, por meio de concentrações e tempos de exposição dos talos, além de identificar a espécie mais sensível. Para isso, nós avaliamos o efeito de diferentes concentrações (0.0, 4.8, 9.6 e 19.2 mg L-1) e tempos de aexposição (24, 48 e 72 horas) ao glifosato, sobre a morfoanatomia, vitalidade do fotobionte, eficiência fotossintética e metabolismo oxidativo dos talos. Nós verificamos que os liquens P. tinctorum e U. barbata respondem ao estresse por glifosato, com perspectivas para serem utilizados no biomonitoramento da dispersão de poluentes a partir de áreas de plantio. Contudo, para o uso de P. tinctorum como bioindicador, a morfoanatomia liquênica, a vitalidade do fotobionte e a concentração de pigmentos fotossintéticos consistiram em biomarcadores eficientes para o efeito de concentração e tempo de exposição. Para U. barbata, a morfoanatomia liquênica, bem como a atividade das enzimas SOD e APX constituíram ferramentas importantes para evidenciar a ação do herbicida. A espécie P. tinctotum, contudo, foi caracterizada como mais sensível, sendo indicada para bioindicar a presença deste herbicida e para diagnosticar a qualidade do ar em áreas urbanas ou fragmentos vegetacionais imersos em matrizes agrícolas.