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Photoacoustic Spectroscopy as a Tool for Monitoring Herbicide Effects on Triazine-Resistant and -Susceptible Biotypes of Black Nightshade (Solanum nigrum)
Published online by Cambridge University Press: 12 June 2017
Abstract
Photoacoustic spectroscopy was used to study effects of atrazine and diuron on excised leaves of triazine-susceptible (S) and -resistant (R) biotypes of black nightshade. Changes of oxygen and photothermal components were compared to photochemical fluorescence quenching obtained by fluorimetry. After 1 h incubation in an aqueous solution of atrazine (0 to 200 μM), oxygen component of the photoacoustic signal was strongly decreased in the S biotype while the R biotype was not affected. Also, reoxidation of the primary quinone acceptor (QA−) of photosystem (PS) II of the S biotype was lower than that of the R biotype. With diuron treatments, changes in the characteristics of these biophysical signals were the same in both R and S biotypes. Both oxygen component and photochemical fluorescence quenching were decreased in treated leaves of the R and S biotypes. By using modulated oxygen and heat emissions, and the ratio of the initial inflection point (I) to the fluorescence maximum (P) as herbicide bioassay indicators, we showed that the photoacoustic spectroscopy was also a reliable technique for whole plant studies. Inhibition of photosynthesis was maximal 2 d after onset of treatment with atrazine (200 μM). Inhibitors of PSII did not induce a significant increase of heat emission in leaves which otherwise showed phytotoxic symptoms after treatment By using the photoacoustic technique, it was possible to obtain useful information on photosynthetic activity under herbicide stress, suggesting that pulsed oxygen emitted by leaves could be used to quantify susceptibility or to detect resistance to many types of photosynthetic inhibitors in weeds and crop plants.
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- Physiology, Chemistry, and Biochemistry
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- Copyright © 1992 by the Weed Science Society of America
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