Studies Of Salt Resistance Of Weigela Florida

The seed and seedlings in Weigela florida was taken as the experiments materials. The growth indices, physiological characteristic, photosynthetic characteristic and ions distribution in different organs of Weigela florida under different levels of salt stress were dertermined in controlled experiments in order to investigate the ability of its saline tolerance and its mechanism of its saline tolerance,which provided effective evidences for its application in the saline-alkali soil and the improvement of ecological environment.The results showed as follows:1. The results showed that the emergence rate of Weigela florida decreased gradually with the increasing of salt concentrations, and decreased obviously when salt concentration≥0.3% . The emergence rate of Weigela florida was 1.7% at salt concentration 0.4% The symptom of the salt injury was not significant when the salt concentrations≤0.3%, but was significant when the salt concentrations≥0.4%.2. The results showed that the inhibition on the biomass,root/shoot ratio and the new tress was not significant when salt concentration≤0.3%. There was a little increasement on the biomass at the salt concentration 0.1%. At the salt concentration 0.4% they decreased obviously. The salt injure index increased gradually with the increasing of salt concentrations. It increased unobviously while salt concentration≤0.2% but increased significantly while salt concentration≥0.3%.3. Activity of SOD protective enzymes decreased when salt concentration≤0.3% and decreased obviously when salt concentration 0.4%. Activity of SOD protective enzymes increased when salt concentration≤0.3% with the increasing of time and decreased obviously when salt concentration 0.4%. Activity of POD protective enzymes do not changes obviously as the activity SOD. Activity of SOD protective enzymes increased when salt concentration≤0.3% with the increasing of time and decreased obviously when salt concentration 0.4%4. The water content decreased gradually but the electrolytic leakage and MDA increased gradually with the increasing of salt concentrations . The rate of increase is gradually reduced. Finally the water content,the electrolytic lealage and MDA changed little.5. The proline contents increased gradually while salt concentration <0.4%,but decreased when the salt concentration was 0.5%.With the prolonging of treatment,the proline content increased at each salt concentration with different rate. After 10 days of salt treatment, the soluble sugar content increased gradually with the increasing of salt concentration and prolonging of treatment, but decreased at the salt concentration 0.5% after the 30 days of salt treatment.6. The content of chlorophyll,Pn,Gs and Tr was enhanced at the salt concentration 0.1%. But decreased while salt concentration≥0.2%. On the contrary, the Ci decreased at the salt concentration 0.1% but increased gradually while salt concentration≥0.3%.The water efficiency was maintained by decreasing Tr while salt concentration≤0.3% but decreased significantly while salt concentration0.4%.With the increasing of PAR, the Pn increased gradually at each salt concentration. The Pn at the lower salt concentration increased more quickly than the Pn at the high salt concentration. Besides the light-compensation point increased with the increasing of salt concentrations,but the light-saturation point decreased.7. With the increasing of salt concentrations the Na⁺ content of root and leaf increased gradually. Na⁺ content accumulation in root was much more than those in leaf because the root stored more Na⁺ and stopped the ion Na⁺ entering into the leaf. The root absorption of the ion K⁺ decreased because of the salt stress so that the K⁺ content of root decreased. But the K⁺ transportation increased significantly so that the K⁺ content of leaf increased. Besides the Ca²⁺ content of root also increased and the Ca²⁺ content of leaf did not decreased for the salt stress. The stronger ability of inhibiting extra much Na⁺to enter into the leaf and the selectively absorption of K⁺ and Ca²⁺ could the key mechanisms of salt-tolerance of Weigela florida.8.According to the analysis of correlation,the biomass,the content of water,SOD,MDA,the electrolytic leakage,the proline content,Pn,Na⁺,K⁺/Na⁺,Ca²⁺/Na⁺ could be utilized as important indexes to messure the salt-tolerance of Weigela florida. SOD have played an important part in the membrance stability of Weigela florida . The proline content and Na⁺ have played an important part in enhancing the osmosis ability of Weigela florida and increasing the water potential of Weigela florida. Besides the proline content played a main role.To conclusion, salt stress seriously affect the emergence rate of Weigela florida, but their seedlings can not grow normally when treated by salt when salt concentration0.4%. The seedlings of Weigela florida may grow normally by self-regulation when salt concentration≤0.3%.