| The following popular vegetables in the market Brassica oleracea, Brassica rapa pekinensis and Spinacia oleracea were selected for a Cd contaminated soil experiment. By analysis their quality, heavy metal content, heavy metal accumulation in the national standard and the vegetables under the good quality relatively were screened. A pot hydroponics experiment was conducted to verify the Daejeon screening test results. Experiments compares Cd species in high and low accumulation, chemical forms of Cd and the difference of subcellular and non-protein thiol (NPT) of Brassica rapa pekinensis. The results on which species uptakes and accumulates high and low Cd as well as Physiological mechanisms are as follows:1. The content of Cd of the23Brassica rapa pekinensis varieties in root in this field trials ranges between0.1994-0.6068mg/kg FW. The excessive rate of Cd in the edible parts of23Brassica oleracea varieties reached95.65%. The integrated pollution index was2.44that reached the level of moderate pollution. The content of Cd in shoots ranges from0.2025^0.5675mg/kg FW in the field. Yield differences in the root of the23Brassica rapa pekinensis varieties in the field reached a significant level. With the range of2341-5433kg/Mu.2. The content of Cd of the28Brassica oleracea varieties in their roots in this field trials is0.0446-0.4364mg/kg FW. The excessive rate of Cd in the edible parts of28Brassica oleracea varieties reached42.85%. The integrated pollution index is1.58which reached the level of light pollution. The content of Cd in shoots of the field was0.0546～0.5043mg/kg FW. Yield differences of roots of the28Brassica oleracea varieties in the field reached a significant level, with the range of3681-8761kg/Mu.3. The content of Cd of the37Spinacia oleracea varieties in the roots ranges between1.2155～2.4612mg/kg FW. The excessive rate of Cd in the edible parts of the37Spinacia oleracea varieties was100%. The integrated pollution index was8.75that reached the level of serious pollution. The content of Cd in the shoots of the plants in the field was1.4494～2.5779mg/kg FW. Yield difference of the plant roots in the field of the37Spinacia oleracea varieties reached a significant level with the range of708-1421kg/Mu. 4. Through the analysis of the results we obtained:The Brassica rapa pekinensis varirties that accumulated high Cd were10and17while the varieties that accumulated low Cd were12and21. High accumulative varieties of Brassica oleracea were8and23, while low accumulative varieties were6and7. High accumulative varieties of Spinacia oleracea were2and4, while low accumulative varieties were8and10. By analyzing the results of three kinds of vegetables, the study recommends Spinacia oleracea. The reason is that the content of Cd was relatively low and the production was high and the economic benefit is considerable.5. In pot experiment, the ground and underground biomass have no significant differences between treatment varieties. Different concentrations of Cadmium, different cadmium accumulation types have remarkable differences in the cadmium content, high accumulation varieties are significantly higher than low accumulation varieties. Different varieties underground part between the cadmium content was not significant. With the increase of cadmium concentration, the cadmium content of the same variety above the ground and underground parts increased significantly.6. In pot experiment, the ground and underground biomass have no significant differences between treatment varieties. When treated with1.0mg/kg of cadmium, the content of cadmium differ from cadmium accumulation types and high accumulative varieties with a significant difference than the low accumulative varieties. With the increase of cadmium concentration, the content of cadmium of the same variety that above the ground and underground part increased significantly.7. According to the field experiment and pot experiment results,10and17are selected for high accumulation of Brassica rapa pekinensis,12and21are selected for low accumulation of Brassica rapa pekinensis;8and232are selected for high accumulation of Brassica oleracea,6and7are selected for low accumulation of Brassica oleracea.8. In the control experiments, the ground and underground biomass significantly reduced when treating with Cd. Cd treatment improved the Non-protein thiol content of three kind of Brassica rapa pekinensis. In leaves and petioles, cadmium exists mainly as sodium chloride extraction state and deionized water extraction state. The chemical form order of cadmium content is as follows:FNac1>Fw≈FHAC>FE>FHc1>FR. In roots, cadmium exists mainly as sodium chloride extraction state and acetic acid extraction state and the chemical form order of cadmium content is:FNaC1>FHAC>FE>Fw>FHC1>FR. In the distribution of cells, in leaves, the F1and F2, F3components allocation proportion are63.7%～74.39%、2.83%～5.8%、19.83%～33.07%, respectively while in roots, the proportion are74.09%～80.96%、1.97%～2.97%,17.08%～22.94%, respectively. The main distribution is cell wall> soluble part>organelles. |
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