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| Physiological responses of Phragmites australis to atrazine exposure and their relevance for tolerance |
| Received:March 29, 2017 |
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| KeyWord:atrazine;Phragmites australis;physiological index;water pollution;tolerance |
| Author Name | Affiliation | E-mail | | WANG Qing-hai | Beijing Research and Development Center for Grass and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | LI Cui | Beijing Research and Development Center for Grass and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | CHEN Chao | Beijing Research and Development Center for Grass and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | CHEN Jie | Beijing Research and Development Center for Grass and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | MA Xue-ju | Beijing Research and Development Center for Grass and Environment, Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China | | | QUE Xiao-e | Institute of Desertification Studies, Chinese Academy of Forestry, Beijing 100091, China | quexiaoe@sina.com |
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| Abstract: |
| To determine the physiological responses of Phragmites australis to atrazine stress and the relationships between these responses and the tolerance of the plant, P.australis was exposed to atrazine(0.5, 1, 2, 4, 8 mg·L-1) for 1 or 2 weeks in a hydroponic system. The effects were evaluated by measuring chlorophyll content, peroxidase(POD) and superoxide dismutase(SOD) activities, and chlorophyll fluorescence kinetics parameters. Moreover, plant relative growth rates based on plant dry biomass were determined for quantitative evaluation of plant tolerance. The relationships of the above-mentioned indexes with plant tolerance were explored by stepwise regression analysis. P.australis survived in culture solution with atrazine concentrations of 8 mg·L-1 or less after 1-week exposure; however, the relative growth rates decreased significantly, and the plant stopped growing when the exposure time reached 2 weeks. Plant chlorophyll a and chlorophyll b in leaves were reduced as the atrazine concentration increased. POD increased significantly with increasing atrazine concentrations after a 1-week exposure. However, this marked increase disappeared after a 2-week exposure to minimum and maximum atrazine concentrations(0.5 and 8 mg·L-1). There were no significant differences in SOD expression compared with the control during the entire cultivation period. As the atrazine concentration increased, Fv/Fm and Fv/F0 ratios were significantly reduced, andqNwas markedly increased. The value ofqNdecreased notably after a 2-week exposure compared with that after a 1-week exposure. Stepwise regression analysis showed that F0 was more closely correlated with the tolerance of P.australis to atrazine than to other physiological parameters. These results indicated that P. australis was relatively sensitive to atrazine but developed tolerance up to 1 week after exposure to atrazine, mainly protecting chloroplasts fromdamage by enhancing the development of nonphotochemical quenching for the dissipation of excess energy. Thus, acertain concentration of chlorophyll was maintained for necessary photosynthesis against atrazine stress. |
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