| 【Objective】The experiment was conducted to study the effects of uranium on the physiological,
biochemical and accumulation characteristics of two kinds of hygrophytes(Alisma plantago-aquatica Linn. and Houttuynia
cordata), and to explore the feasibility of its application in uranium contaminated water remediation.【Method】Different
uranium treatment concentrations (5, 30, 55 mg/L) were set for hydroponic experiments, repeated for 3 times in each
treatment. After 21 days, activity of oxidase, photosynthetic parameters, fluorescence parameters, malondialdehyde and
soluble protein contents were determined.【Result】The results show that, the antioxidant enzyme activity of Alisma
plantago-aquatica Linn and Houttuynia cordata showed a trend of increasing first and then decreasing under different
concentrations of uranium treatment. At the uranium concentration of 30 mg/L, the antioxidant enzyme activities of peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) of the two plants all reached the maximum values, which
increased by 11.79%, 114.69%, 69.64% and 6.03%, 19.91% , 10.71% , respectively, compared with those of the control group.
With the treatment of uranium concentration of 55 mg/L, the MDA content of the two plants reached the highest level, which
increased by 70.42% and 55.42%, respectively compared with that of the control group. At different uranium concentrations,
the photosynthetic parameters (photosynthetic rate (A), stomatal conductance (Gs), intercellular CO2 concentration (Ci) and
transpiration rate (Tr)) and chlorophyll fluorescence parameters (maximum photochemical efficiency (Fv/Fm), photosynthetic
performance index (PIABS) of the two plants were influenced differently. At the uranium concentration of 55 mg/L, the Ci of
leaves of two plants decreased by 13.14% and 27.49% respectively, compared with that of the blank control group. The leaf Tr
of both plants increased first and then decreased, while the leaf Gs of Alisma plantago-aquatica Linn increased first and then
decreased. The leaf Gs of Houttuynia cordata increased gradually. The photosynthetic rate of the two plants decreased most
obviously at uranium concentration of 55 mg/L, which was 55.19% and 85.92% lower than that of the control group, respectively.
Compared with that of the control group, Fv/Fm of the two plants decreased by 25.27% and 1.45%, respectively. PIABS of the
two plants increased first and then decreased. At uranium concentration of 5 mg/L, the PIABS of Alisma plantago-aquatica Linn
reached the maximum value, which was 146.43% higher than that of the control group, and PIABS of Houttuynia cordata was
86.57% higher than that of the control group at uranium concentration of 30 mg/L. (3) The enrichment concentration of uranium
in plants reached the maximum value at 55 mg/L, and the enrichment concentrations of the stem, leaf and root reached 2 778.74,
10 393.94 mg/kg and 3 184.91, 6 515.00mg/kg, respectively.【Conclusion】Alisma plantago-aquatica Linn and Houttuynia
cordata have certain enrichment ability and tolerance to uranium. |
