The Research On The Physiological And Chemical Characteristic Of Vicia Faba Cultivating In Se-Cd Compounds

Selenium(Se) is necessary for human beings and animals,and is very important for plant growth. People absorb Selenium directly or indirectly from plants, and following the fast development of modern industry, Selenium now becomes a potent and risky chemical to environment. Following more and more product in the form of Selenium,Selenite is commonly used as the additive of selenium supplement. But the more Selenium people absorb,the more toxic people people will become. So it has become important to study the effects of selenium to plants.We investigated antioxidant enzyme system in the root of Vicia Faba by cultivating it in different concentration of Cd,Se and Se-Cd compounds and for different time. The results showed that following the increasing concentration of Cd ,SOD activity ,POD activity and the content of soluble protein increase and then decreases, the peak concentration of SOD activity and the content of soluble protein were 0.05 mmmol/L, and that of POD activity was 0.02 mmmol/L, the CAT activity decreased and the content of MDA increased following the increasing concentration of Cd. SOD activity increased and CAT activity decreased with the increasing concentration of Se; POD activity decreased when the concentration was lower than 0.01μmol/L Se4+ and then increased with the increasing of concentration;the content of MDA decreased when the concentration was lower than 0.005μmol/L Se4+ and then increased with the increasing of concentration. The results indicated that plants had anti-oxidant ability in the low concentration cultivating, and had pro-oxidant ability in the high concentration cultivating. Furthermore, this ability had something to do with the cultivating days. The fewer days plants be cultivating, the more antioxidant effects; the more days, the fewer. By polyacrylancide gel electrophoresis(PAGE) under cultivating for 96h, different concentrations of Se4+ did not induce the expression of new POD isoenzymes, but the activities differed, some strips disappeared.In the Se-Cd compounds simultaneously treating group,SOD activities decreased generally with the increasing concentration of Se in the compounds;POD activities increased when the concentration of Se was lower than 0.01μmol/L and the content of soluble protein increased when the concentration of Se was lower than 0.05μmol/L,then decreased;CAT activities increased;the content of MDA decreased to the lowest when the concentration of Se was 0.05μmol/L,and then increased,so we can conclude Se can alleviate the damage brought by Cd to some extent.In different cultivating group, group of Se4+Cd2 had the best effect,which showed that the alleviation of Se decreased with the postphoning of adding Se. By polyacrylamide gel electrophoresis(PAGE), the strip of P5 and P6 became dark in the 500μmol/L Cd stress ,which indicated that POD activities decreased. The new strip P3 appeared under cultivating for 96h in group of Se4+Cd4. These results suggested that Se supplementation proved to be inhibitory for Cd induced oxidative stress and beneficial for the plant's survival.