| Soil salinization is one of the main ecological problems facing the contemporary.The use of salt-tolerant plants for saline-alkali soil improvement has become one of the key research directions.Zoysia matrella(L.)Merr.has good growth ability and ornamental ability which was widely planted in southern China.Because of its good salt tolerance,Zoysia matrella is also an excellent plant choice for improved cultivation of saline-alkali soil.However,due to the limitation of its salt tolerance,it is still unable to adapt to the environment of some high-salt saline-alkali soils,which makes it can not be used intensively in practical applications.Because 93.94%of the saline-alkaline soil components are Na+ and Cl-,the NaCl treatment was used to simulate the growth environment of saline-alkali soil.The salt tolerance of callus and regeneration of Zoysia matrella was investigated by different salt concentration treatments.And different concentrations of epibrassinolide(EBL)were added under salt stress to analyzed the effects of EBL on the salt tolerance of callus and regeneration of Zoysia matrella.Trying to find the optimum treatment concentration that enhanced the salt tolerance of callus and regenerated plants of Zoysia matrella.We explored new ideas for improving the salt tolerance of Zoysia matrella through this experimentation.After the treatment with a series of salt concentrations and EBL concentrations,the changes of morphological and physiological indexes of callus and regenerated plants were measured and analyzed.We got the salt tolerance ability and the influence of EBL to the salt tolerance of Zoysia matrella from that.And the main findings are as follows:(1)The callus and regenerated plants of Zoysia matrella have good salt tolerance.Different salt concentration treatments had different effects on their growth and regeneration.From the analysis of morphological indexes,the growth status of callus and regenerated plants increased first and then decreased with the increase of salt concentrations.At low salt concentrations,callus can grow and regenerate normally.When the salt concentrations were?0.6%,the growth of callus was inhibited and the callus regeneration was inhibited when the salt concentrations were?0.4%.From the physiological indexes,the activity of protective enzymes in callus and the leaves of regenerated plants increased with the rise of salt concentrations.While the activity of some protective enzymes decreased at high salt concentrations.The content of MDA was gradually increased with the rise of salt concentrations,and also the decrease was observed at high salt concentrations.It indicated that the callus and regenerated plants of Zoysia matrella have good salt-tolerant physiological mechanism under salt stress,but they are gradually lost under high salt concentrations.(2)EBL treatment in the appropriate concentrations range has a significant effect on the salt tolerance of the callus and regenerated plants,and the promoting effect is enhanced with the increase of EBL concentrations.From the analysis of morphological indexes under different concentrations of salt stress,when the EBL concentration was 0.05 mg·L-1,the diameter growth rate and fresh weight growth rate of callus were the highest.While the EBL concentration was 0.02 mg·L-1,The callus regenerated plants had the roots with lengths?5 mm,the amount of plantlets,the total number of buds and the regeneration rate in the highest level.From the physiological indexes,when the EBL concentration was 0.05mg·L-1,the CAT,POD and SOD activities of the callus were the strongest and the MDA content was the lowest.And the CAT,POD and SOD of the regenerated plants were the most active and the MDA content was the lowest when the EBL concentration was 0.02mg·L-1.That is,0.05mg·L-1 EBL is the optimal treatment concentration for improving the salt tolerance of callus,as well as 0.02mg· L-1EBL is the best treatment concentration for improving the salt tolerance of callus regenerated plants.(3)High-concentration EBL treatment inhibits the growth and regeneration of callus of Zoysia matrella.Under salt stress,the growth and regeneration of callus showed inhibition as the concentrations of EBL continued to increase.When the EBL concentrations were?>0.1mg· L-1,the growth of callus decreased,some morphological indexes were even lower than the control,the protective enzyme activities decreased while the MDA content increased.When the EBL concentrations were?>0.05mg· L-1,the growth of callus regenerated plants decreased and some morphological indexes were lower than the control,the protective enzyme activities decreased,while the MDA content increased.It indicated that with the continuous increase of EBL concentrations,its promoting effect on the salt tolerance of Zoysia matrella callus is gradually lost,and high-concentration EBL even shows inhibition on growth.(4)EBL has practical significance for improving the salt tolerance of Zoysia matrella.In the experiment,EBL significantly promoted the protective enzyme system in callus and regenerated plants of Zoysia matrella,and protective enzymes as one of the main physiological mechanisms of salt-tolerant plant stress resistance had an important impact on plant salt tolerance.This experiment has achieved the goal of obtaining more salt-tolerant plants of Zoysia matrella,and provides inspiration and reference for the application of sparging-EBL to improve the salt tolerance of Zoysia matrella plants.It is also used as a basis for the improvement of saline-alkali land. |
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