Cr‘S POLLUTION AFFECTED CONTENT OF ELEMENTS IN THE LEAVES OF TRAPA BISPINOSA Photosynthetic Physiological Characteristics and Ultrastructure of Salvinia natans Leaves under Cr6+ Stress Effects of Cr 6+on the growth and some physiological characters of tobacco by tissue culture Toxic Effects of Cr6+ on Chlorophyll Fluorescence Parameters,Antioxidant Systems and Ultrastructure of Potamogeton crispus The Sub cellular Chromium (Cr6+) Distribution and Tolerance Mechanism to Chromium Stress in Different Tolerant Brassica chinensis L. Cultivars The Effects of Cr6+‘s Pollution on the Ultrastructure of Hydrocharis dubia and Cell Membrane of H.verticillata,Brasenia schreberi,Trapa bispinosa Zn2+ and Cr6+ Synergetic Toxic Effects on Ottelia alismoides Physiological and ecological characteristics of Cyperus malaccensis to Cr6+ stress Effects of Cr6+ stress on 5-MeC content of DNA in wheat seedlings Toxic of chromium(Cr6+)on the callus of Alternanthera philoxeroides