TOXICITY OF HEAVY METALS TO HORDEUM VULGARE
Zhang Yixian(Department of Life Science, Shanxi University, Taiyuan 030006)
The toxic effects of six heavy metals (Hg 2+ , Cd 2+ , Pb 2+ , Ni 2+ , Cu 2+ , Zn 2+ ) at different concentrations on H ordeum vulgare seedlings were studied. The results indicated that the percentage of seed germination rate of root growth and mitotic index decreased progressively with the increasing of concentrations of heavy metals and treatment durations. After 24 h treatment with 1×10 -2 mol/L Hg 2+ , Cd 2+ , and Pb 2+ , cell division was completely inhibited by Hg 2+ , Cd 2+ , Pb 2+ . The total frequency of chromosomal aberrations induced by Hg 2+ , Cd 2+ , Pb 2+ was higher than that of Ni 2+ , Cu 2+ and Zn 2+ . After the treatment with Hg 2+ , Cd +2 , Pb 2+ at concentrations of 5×10 -3 —5×10 -4 mol/L for 24 h and Ni 2+ at same concentration for 48 h, the nucleolus was disintegrated and forming a large amount of nucleolar particles which go into the cytoplasm from the cell nucleus. But after the treatment with Cu 2+ and Zn 2+ , the nucleous was not affected. The order of six heavy metals on cytogenetical toxical effects is Hg 2+ Cd 2+ Pb 2+ Ni 2+ Cu 2+ Zn 2+ . The possible mechanism of poisoning of heavy metals on plant cells was also discussed.