title: Atrazine and Methyl Viologen Effects on Chlorophyll-a Fluorescence Revisited-Implications in Photosystems Emission and Ecotoxicity Assessment.
abstract: In this work, we use the effect of herbicides that affect the photosynthetic chain at defined sites in the photosynthetic reaction steps to derive information about the fluorescence emission of photosystems. The interpretation of spectral data from treated and control plants, after correction for light reabsorption processes, allowed us to elucidate current controversies in the subject. Results were compatible with the fact that a nonnegligible Photosystem I contribution to chlorophyll fluorescence in plants at room temperature does exist. In another aspect, variable and nonvariable chlorophyll fluorescence were comparatively tested as bioindicators for detection of both herbicides in aquatic environment. Both methodologies were appropriate tools for this purpose. However, they showed better sensitivity for pollutants disconnecting Photosystem II-Photosystem I by blocking the electron transport between them as Atrazine. Specifically, changes in the (experimental and corrected by light reabsorption) red to far red fluorescence ratio, in the maximum photochemical quantum yield and in the quantum efficiency of Photosytem II for increasing concentrations of herbicides have been measured and compared. The most sensitive bioindicator for both herbicides was the quantum efficiency of Photosystem II.
authors.affiliation: Centro de Estudios Transdisciplinarios del Agua, Facultad de Ciencias Veterinarias, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Analia
authors.initials: A
authors.lastname: Iriel
authors.affiliation: INQUIMAE/ Dpto. de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina.
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Novo
authors.affiliation: LART-IFEVA/ Dpto. de Métodos Cuantitativos y Sistemas de Información, Facultad de Agronomía, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Gabriela B
authors.initials: GB
authors.lastname: Cordon
authors.affiliation: INQUIMAE/ Dpto. de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina.
authors.forename: María G
authors.initials: MG
authors.lastname: Lagorio
mesh_terms: D001280:Atrazine / Q000633:toxicity*; D002734:Chlorophyll / Q000378:metabolism*; D005453:Fluorescence; D006540:Herbicides / Q000633:toxicity; D010269:Paraquat / Q000633:toxicity*; D045331:Photosystem I Protein Complex / Q000187:drug effects*; D045332:Photosystem II Protein Complex / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects* / Q000378:metabolism
chemical_list: D006540:Herbicides; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D010269:Paraquat; D001280:Atrazine