The Effect Of Heavy Metal Cd On Growth And Physiology Of Two Species Of Sedum

In this experiment,Sedum spectabile Boreau and Sedum spectabile were selected as the experimental material.Using laboratory hydroponics,the root exudates,morphological indexes,physiological indexes were determined,under heavy metal Cd stress with different concentration.The endurance and resistance mechanism of two Sedums to Cd were researched.The main research results are as follows:1.With the increment of cadmium concentration,the root biomass,stem biomass and leaf biomass of two Sedums showed a decreasing trend.The higher the concentration was,the stronger inhibitory effect of Cd on two Sedum biomass was observed.However,there was no significant difference between the biomass with cadmium stress and the biomass of control.With the increment of cadmium concentration,the root total length,root surface area,root diameter,root volume,tip number and root furcation number of Sedum spectabile Boreau and Sedum spectabile were decreased.Sedum spectabile Boreau root total length,root surface area,root diameter,root volume,root tip number and root furcation number were significantly inhibited under the cadmium stress with high concentration(200?mol/L).There was no significant inhibitory effect on the root mean diameter and root volume of Sedum spectabile.2.For Sedum spectabile Boreau,with the increase of cadmium concentration,the concentration of oxalic acid,tartaric acid,fumaric acid and succinic acid in root wes increased.The concentration of tartaric acid and succinic acid were highest,followeed by oxalic acid,acetic acid,and fumaric acid,while citric acid was not detected.For Sedur spectabile,with,the increase of cadmium concentration,the concentration of acetic acid and fumaric acid in root was increased gradually.The concentration of acetic acid and fumaric acid were the highest,followed by succinic acid and oxalic acid,while tartaric acid and citric acid were not detected.The results showed that with the increase of cadmium concentration,the secretion of organic acids was promoted,thus,plants can be protected by organic acids speculatively.The effects of cadmium on the organic acids in roots of different Sedum cultivars were different.3.The protective enzyme activity SOD and POD of two Sedum could be significantly promoted by Cd stress with low concentration(50 mol/L)and moderate concentration(100 mol/L).The activity of the two enzymes was significantly inhibited by Cd stress with high concentration(200 mol/L).The MDA content of two Sedums was promoted by Cd stress with low,moderate and high concentrations.Proline concentration was promoted by Cd stress with low and moderate concentration Cd treatment.Proline content was inhibited by high concentration Cd treatment.4.Sedum spectabile Boreau and Sedum spectabile are potential materials for phytoremediation.They both can be used in cadmium contaminated soil.