| Lead is a kind heavy metal of abroad use and high toxicity. In recent decades, as the development of industry and agriculture, science and technology, the lead is used more and more, as a result, it polluts human beings' habitation seriously and intimidated the human beings' health. The restoration of lead contamination became more important.In this paper, the effects on the seed germination and the germination physiology treated by different concentrations, as well as the growth of the plant, the physiological item such as content of chlorophyll, electrolyte leakage, content of Pro, NR activity, POD activity, and the lead utake, distribution, bioaccumulation of lead in plants were studied on Gleditsia japonica, Robinia pseudoacacia, by germination experimentation in laboratory(the lead concentration:0mg/L, 200mg/L, 400mg/L, 800mg/L, 1200mg/L, 1600mg/L) and potted outside(the lead concentration:0mg/kg soil, 200mg/kg soil, 400mg/kg soil, 800mg/kg soil, 1200mg/kg soil, 1600mg/kg soil), in order to learn this two plants lead tolerance and restoration mechanism of the lead contaminated soil. The main results are shown as follows:1. Experimentes in laboratory indicated different lead concentration almost had no affection on Gleditsia japonica germination rate or germination potential, but had different level of inhibition on the seed germination of Robinia pseudoacacia, Along with the concentration creased, the lead inhibition on the lengthening of two seeds' radicles and hypocotyls became stronger, and the inhibition on radical was stronger than that of hypocotyls. The Gleditsia japonica seedlings could grow normally in the lead concentration of 200mg/L, the Robinia pseudoacacia was sensitive to lead even at the lowest content (200mg/L), its fresh weight was significant to that of the contrast. The activity of POD in both two radicals had the trend of enhancement; the activity of POD in Gleditsia japonica hypocotyl decreased as the lead concentration increased; the activity of POD in Robinia pseudoacacia hypocotyl increased at the content of 200mg/L, 400mg/L, and at the content of 800mg/L it got the peak value, and decreased afterwards; the germination of plants grown in soil had no difference treated by different concentrations of lead2. The height, diameter, dry weight of potted Gleditsia japonica and Robinia pseudoacacia were restrained by different degree; the low lead concentration can stimulate to synthesize the chlorophyll, high lead concentration restrain the chlorophyll to synthesize; Along with the lead concentration creased, the electrolyte leakage, content of Pro creased; the lead had strong inhibition on the activity of NR; and the POD activity creased at the low lead concentration and decreased afterward. Considering lead concentration under 800mg/kg soil could be an extension for these two plants to grow.3. The lead content in different apparatus creased as the supplied lead creased in the same time, and the lead content in root and stem creased as the intimidated time prolonged, the lead content in each apparatus was root＞stem＞leaf; the stem translocation factor of each level of Gleditsia japonica was almost smaller than 0.3, the stem translocation factor of Robinia pseudoacacia was bigger than 0.5, the stem translocation factor of CK both in Gleditsia japonica and Robinia pseudoacacia was big, about 1.0, the leaf translocation factor of both the two plants in CK was 0.5, 0.7 respectively, bigger than each treatment. The bioaccumulation coefficient of the root, stem and leaf of Gleditsia japonica was 0.1, 0.03, 0.02 respectively, that of Robinia pseudoacacia was 0.1, 0.06～0.1, 0.02 respectively, the ability of different apparatus to bioaccumulate lead was root＞stem＞leaf, the bioaccumulation coefficient became smaller as the lead concentration creased.5. Robinia pseudoacacia can localized much lead in the stem, about 50%～60% of the total heavy metal translocation, Gleditsia japonica deposited a majority of lead in the root, about 60%～70% of total heavy metal uptake. The total heavy metal uptake of a single plant of Gleditsia japonica grown slowly as the supplied lead creased, and in a certain more content extension, the total heavy metal uptake could still grow; The total heavy metal uptake of a single plant of Robinia pseudoacacia grown quickly at the low lead concentration as the applied lead creased, and then went gently. When the lead concentration was under 800mg/kg, Robinia pseudoacacia' total heavy metal uptake was more than than of Gleditsia japonica; when the lead concentration was between 1200mg/kg and 1600mg/kg, Gleditsia japonica' total heavy metal uptake was more than than of Robinia pseudoacacia. |
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