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| Photosynthetic response of ryegrass to uranium stress and the absorption characteristics of enriched uranium |
| Received:March 05, 2019 |
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| KeyWord:ryegrass;uranium;photosynthetic gas parameter;photosynthetic fluorescence parameter;cumulative feature |
| Author Name | Affiliation | E-mail | | ZHAO Ji-wu | Life Science and Engineering College, Southwest University of Science and Technology, Mianyang 621010, China | | | LUO Xue-gang | Life Science and Engineering College, Southwest University of Science and Technology, Mianyang 621010, China | lxg@swust.edu.cn | | WANG Zhuo | Life Science and Engineering College, Southwest University of Science and Technology, Mianyang 621010, China | | | HUANG Qiang | Life Science and Engineering College, Southwest University of Science and Technology, Mianyang 621010, China | |
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| Abstract: |
| In this study, we investigated the changes in the photosynthetic characteristics and the distribution of uranium in various parts of ryegrass grown in uranium-contaminated soil. Specifically, we determined changes in photosynthetic gas exchange and fluorescence parameters of ryegrass and uranium enrichment characteristics under different uranium concentrations. The results showed that uranium stress caused a significant decrease in photosynthetic rate and stomatal conductance of ryegrass plants; moreover, it promoted an initial increase and subsequent decrease in the photosynthetic performance index. However, it did not significantly affect the intercellular CO2 concentration, the maximum photochemical efficiency, or the relative variable fluorescence of ryegrass leaves. Our results also revealed that the amount of uranium remaining in the soil and the accumulation of uranium in the above-and belowground parts of plants increased significantly with an increase in the content of exogenous uranium. With an increase in growing time, the amount of uranium remaining in the soil decreased significantly, whereas the cumulative amount of uranium in the above-and belowground plant parts increased significantly. Furthermore, the bioconcentration factor and total uranium extraction of ryegrass reached maximum levels at 100 mg·kg-1. The photosynthetic fluorescence parameters of ryegrass indicate that ryegrass has a high tolerance to uranium as well as a high enrichment capacity for uranium, which increases with time and increasing exogenous uranium concentration. |
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