Study On The Characteristic Of Physiological And Biochemical In Perennial Plants Limonium Aureum(L.) Hill Under Salt Stress

Soil salinization is one of the major environmental problems in the present countries around the world, which influencing the agriculture development and the sustainable use of natural resources, even endangering human's social environment and health. Excessive salt has toxic effects on plants, and affects plant growth and development, photosynthesis, lipid metabolism, protein synthesis and other important metabolic activities of plants. Perennial plants Limonium aureum?L.? Hill. widely distributed in the northwest, northeast and north of china, which played an important ecological role in improving saline alkali soil. In this study,Halophyte Limonium aureum?L.? Hill seedlings were used as materials to investigate the changes of various physiological indexes in respones to different NaCl concentrations in order to explore the physiological mechanism of salt tolerance in plants. The main results were presented as follows:1.Different concentration of NaCl treatment induced the increase of Na content, but decreased the content of K and Ca significantly in L. aureum seedling leaves. Zn content was significantly decreased under 100 and 150 mmol·L^-1 NaCl treatments, while 150mmol·L^-1 NaCl promoted the absorption of Fe content, Cu content increased only exposed to 25 mmol·L^-1 NaCl concentration. In addition, the content of Mn increased first and then decreased following the increasing of NaCl concentration.2.NaCl treatment significantly stimulated the level of Nitric oxide?NO?, as well as Nitric oxide synthase?NOS? activity in the leaves of L. aureum seedling.3.Except for increased hydroxy radical?·OH? content due to 150 mmol·L^-1 NaCl, different NaCl concentrations resulted in the reduction of this paraneter in the L. aureum seedling leaves. Differently, hydrogen peroxide?H₂O₂? content significantly rose in response to100 and 150 mmol·L^-1 NaCl.4.All salinity concentrations stimulated superoxide dismutase?SOD?, peroxidase?POD?,ascorbate peroxidase?APX?, diamine oxidase?DAO?, polyamine oxidase?PAO?,glutathione reductase?GR?, ascorhic oxidas?AAO? and dehydroascorbate reductase?DHAR? activities, but inhibited cell wall-bound POD and monodehydroascorbate reductase?MDHAR? activities in the leaves of L. aureum seedling. In addition, catalase?CAT? activity rose due to low salinity concentrations but lowered to high NaCl concentrations in the leaves.5.Ascorbic acid?AsA? and total ascorbic acid?AsA+DHA? contents rose only due to 150mmol·L^-1 NaCl concentration. Different salinity concentration led to the increasing of dehydroascorbate?DHA? content and GSH/GSSG, but decrease the AsA/DHA and GSSG level. In addition, GSH content increased in low NaCl concentration but decreased in high salinity in the leaves of Limonium aureum?L.? Hill seedlings.In conclusion, these results suggested that: NaCl treatment caused excessive accumulation of Na, inhibited the absorption of K, Ca, Zn, Mn and other mineral nutrients in the leaves of Limonium aureum?L.? Hill seedlings, which destroyed the absorption of ion and nutrients and caused damage to plant; Salinity stress induced the accumulation of NO, H₂O₂ and ·OH, initiated reactive oxygen species scavenging mechanism, also enhanced the activity of antioxidant enzymes?SOD, POD, CAT, APX, GR, AAO and DHAR? as well as the non enzymatic antioxidant?AsA, GSH and GSH/GSSG? and prevented excessive damage caused by oxidative stress in seedlings. Additionly, the incresed NOS activity induced by NaCl stress may be responsible for the production of NO, the enhancement of DAO and PAO activities may be related to the accumulation of H₂O₂.