| With the rapid development of the economy and acceleration of urbanization process in many coastal areas, coastal beach soil pollution has been increasingly serious as the development and utilization of shoal land and the increasing intensity of discharging land-sourced pollutants into the sea, especially Cd content has been significantly exceed the standard in some areas. Although a great number of plant have been investigated and some plant have been proven to be applicable to remedying soil contaminated by heavy metal, these plants that are glycophytes are not applicable to remediation of heavy metal contaminated soil. Taking Suaeda salsa. as a research object, this paper is to investigate the growth response, Cd and Na accumulation, antioxidant enzyme activities, subcellular distribution, sulfhydryl compounds, and so on in order to providing a theoretical basis the mechanism of Suaeda salsa. response to NaCl and Cd stress and investigating remedying tidal flat soil contaminated by Cd. The main results were indicated as follows:1. Accumulation, translocation and detoxification of Cd in S. salsa under under treatments of Cd and NaClInfluence of Cd (0、5、10、20 μmol·L-1) and NaCl (0、50、100、200 mmol·L-1) combined stress on the growth response, Cd and Na accumulation, antioxidant enzyme activities, chlorophyll, TBARS, subcellular distribution, sulfhydryl compounds was studied with the hydroponics experiment. The results show that:the plant growth was restained with the of Cd level increase, while the water content increased with the NaCl content increased. The fresh weight of S. salsa with Cd treatment was significantly lower than that without Cd. Accumulation of Na was not affected by Cd, but absorption and accumulation of Cd were significantly affected by Cd and NaCl interaction. Cd was mainly accumulated in root, and most of them were adsorbed on the cell wall. But a majority of Na was translocated to the shoot, Na concentration in the leaves, stems and roots significantly increased with the NaCl content increased, and most of Na in the root were adsorbed on the cell wall. SOD, CAT, TBARS and chlorophyll in the leaves increased with the NaCl content increased under no Cd content. But within the Cd addition, Cd had a significant impact on SOD, CAT, TBARS and chlorophyll. NPT and GSH content in roots had been on an upward trend with the of NaCl level increase, this indicated that more sulfhydryl compounds was induced to alleviate Cd toxicity in the root.2. Phytoremediation of Cd polluted saline soils by the halophyte Suaeda salsaIn this study, a pot experiment was conducted to investigate the growth response, Cd and Na accumulation of Suaeda salsa under treatments of Cd (0—5.0 mg·kg-1) and NaCl (0.1%—1.0%). In the soils containing 0.5% and 1.0% NaCl, the growth of S. salsa was significantly inhibited. The plant biomass decreased with the of Cd level increase, while the Cd accumulation increased with the NaCl content increased. In the root, stem and leaves of S. salsa, Cd concentrations were the highest (35.3,30.1 and 30.9 mg·kg-1, respectively) at the 0.1% NaCl and 2.5 mg·kg-1 Cd treatments. The bioconcentration factor of Cd in the shoots were 0.9—19.9, and the Cd accumulation in shoots was 8.1—73.6 times of roots. Fresh weight, Cd and Na concentration in the root of S. salsa were significantly affected by NaCl and Cd interaction. However the interaction was not significant for the Cd and Na concentrations in the stem and leaves. In the presence of Cd, Na contents in the stem and leaves increased with the NaCl content increased, but within the same Na addition, Cd did not lead to significantly in different Na contents compared to the control. On the contrary, NaCl enhanced the accumulation of Cd in S. salsa. Sodium accumulation of S. salsa was only affected by the NaCl treatments. These results showed that S. salsa was Cd-tolerant and may strongly accumulate Cd, making it suitable for the phytoremediation of Cd-contaminated saline soils. |
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