Study Of Lythrum Salicaria's Form Response And Distribution To Lead

Wetland, an unique kind of ecosystem, is important for human beings'survival and sustainable development. But the heavy metal pollution of wetland is more and more serious in recent years. There are varieties of methods available to repair the wetland environment, and phytoremediation is one of the critical methods. In this experiment, the seed germination, the form response and the distribution of Ly thrum salicaria to lead were studied by using paraffin, scanning electron microscope (SEM), the energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). The main results are summarized as follows.1. It's found that under low concentration of Pb(NO3)2 solution(100mg/L) treatment, Lythrum salicaria could grow normally. But when the concentration was more than 100mg/L, the seed germination and growth were inhibited. And with the increasing concentration of lead, the inhibition was enhanced. So the results showed that seed has some lead tolerance, and it provided the possibility that Lythrum salicaria can be used to repair certain concentration of lead contaminated soils.2. The findings in the lead stress test suggested that, root epidermis were wrinkled, and the epidermal and cortex cells were arranged looser than that of in the control. Stem appeared little distortion, but no significant changes were observed in internal organization. Additionally, the numbers of stomata and trichomes on the leaf lower-surface increased, and mesophyll cells were looser arranged and its intercellular space was larger. It's suggested that Lythrum salicaria could exhibit some form response under lead stress.3. The level of lead in different organs and tissues was significantly uneven. Specifically, the amount of lead in roots was greater than in above-ground part of plants. Moreover, it's mostly accumulated in the epidermis of roots and stems. While, in the leaf, trichomes were the main part of lead enrichment, and in the same trichomes from base to top, the level of lead was gradually increased.According to the distribution of lead in different organs and tissues, the means of transportation and detoxification of lead was that, with being absorbed by the roots and transported by the stem, lead enriched in leaf trichomes finally. Then that was the transportation process of lead in plants. Accordingly during the procedure, lead accumulated in the epidermis constantly. Therefore, root and stem epidermis, and leaf trichomes should be looked as the main structure of excreting lead in Ly thrum salicari.