Effects of Lanthanum on Physiological Characteristics in Ryegrass Seedling Roots under NaCl Stress

The changes in the metabolism of active oxygen and the contents of osmoticum from root tips of perennial ryegrass(Lolium perenne L.) seedling under NaCl stress were investigated by a hydro culture method in the presence or absence of La(NO3)3.The results indicated that under NaCl stress,the contents of malondialdehyde(MDA),O2.-and H2O2 in ryegrass roots increased gradually with increasing NaCl concentration,the activities of catelase(CAT),guaiacol peroxidase(POD),ascorbate peroxidase(APX) and the contents of ascorbic acid(ASA),reduced glutathione(GSH),soluble protein and proline increased and then decreased,superoxide dismutase(SOD) activity and the contents of soluble sugar,Na+ increased,while K+ content and plasma membrane H+-ATPase activity decreased unceasingly;compared with the NaCl stress treatment the addition of exogenous 20mg/L La(NO3)3 increased the activities of SOD,CAT and plasma membrane H+-ATPase and the contents of ASA,GSH,soluble protein,soluble sugar and K+,but decreased the APX activity and the contents of O2.-,H2O2,MDA,proline and Na+ in the root tips of ryegrass seedling;POD activity decreased at low concentration(50 and 100mmol/L NaCl) while increased at high concentration(200mmol/L,300mmol/L).These findings suggested that appropriate concentration of La(NO3)3 could decrease the lipid peroxidation caused by salt in ryegrass roots via increasing the ability of scavenging reactive oxygen and osmotic adjustment,thus improves salt resistance of the ryegrass plants.