Effect Of Heavy Metal Stress On Physiological And Biochemical Indexes In Hordeum Vulgare

The Cd, Pb, Hg and Ni of heavy metals exist in the environment widely , and have strong toxicities to the organism. We selected barley as the material in our experiment, by indoor foster method, and study the effects of the Cd²⁺, Pb²⁺ , Hg²⁺ and Ni²⁺ on barley from the aspects of physiology and bio-chemistry. There are four parts in my thesis.1 Effects of heavy metal on the growth of barley seedlingUsing different concentrations of (1 mg·L^-1, 10 mg·L^-1, 50 mg·L^-1, 100 mg·L^-1) Cd²⁺ ,Pb²⁺, Hg²⁺,Ni²⁺ to deal with barley seedling, measure their mail roots length, leaves height and the content of chlorophyll in leaves of barley seedling after 4 and 10 days. The results show that different concentrations of four sorts of metal all produce inhibition of different degrees to the growth of barley seedling, and with the time process, inhibition are more remarkable. Four sorts of mental produce more strong inhibition to the growth of barley roots than the leaves of seedling. The same kind of metal has different influence to chlorophyll in different concentrations, lower concentration promote growth and higher concentration restrain growth, and the inhibition become strong along with the managed time process.2 Effects of heavy metal stress on anti-adversity physiology of barley rootsUsing the different density (1 mg·L^-1, 10 mg·L^-1, 50 mg·L^-1, 100 mg·L^-1) Cd²⁺, Pb²⁺, Hg²⁺, Ni²⁺ to deal with roots of barley seedling , and then mensurate their MDA content, the electric conductivity rate of root cells exosmosis liquor and the content of proline and solube sugar in roots after 4 days. The result indicate that under 1-100 mg·L^-1 Cd²⁺, Pb²⁺, Hg², Ni²⁺ stress, with the heavy mental concentration increase, the content of MDA of the barley roots and the opposite electric conductivity rate of the root cellsexosmosis liquor gradually increase;with the heavy mental concentration increase,the content of proline firstly decline ,and then increase;with the heavy mental concentration increase,the content of soluble sugar decline,so the content of soluble sugar have a remarkable negative pertinence with heave metal concentration.3 Effects of heavy metal on antioxidant enzymatic activities of barley seedlingThis study examined the individual effects of Cd2"\ Ni2"\ Pb2+> Hg2+on the enzymatic activities of superoxide (SOD), peroxidase (POD) and catelase (CAT) in Hordeum vulgare. The seedlings were exposed to each of metal ions at the concentrations from 1 to 100 mg-L"1 after 4 to 6 days. The following enzyme kinetic analysis showed either enhanced or inhibited catalytic activities depending on ion species and enzyme. The ions of Pb2+ and Ni2+ showed enhancing effects on SOD and CAT, whose activities gradually increased along with the increase in metal concentrations and exposure duration; the POD's activity increased at and but later decreased. The Cd2+ was found enhancing POD and SOD activities at low concentrations but inhibiting them at higher concentrations, whereas Cd also consistently inhibited CAT at all the concentrations used in this study. Such steady inhibiting effects were also observed in Hg2+ to SOD, POD and CAT. A further observation about these antioxidant enzymes of SOD, POD and CAT demonstrated that they are more resistant to Cd and Hg in leaves than in roots.4 Effects of heavy metal on antioxidant enzyme isoenzymes expression of barley SeedlingAdopting polyacrylamide gel electrophoresis(PAGE) method, this study examine that the effects of different Cd2+> Pb24\ Hg2^\ Ni2+ concentration (1 mg-L"1 > 10 mg-L"1 > 1 OOmg-L"') on the changes of the isoenzyme pedigree of superoxide (SOD), peroxidase (POD) and catelase (CAT) in Hordeum...