Mitigation Effect And Regulation Mechanism Of Three Exogenous Substances On Glycine Soja Under Salt Stress

Soil salinization is a global problem that affects the ecological environment and agricultural production.How to effectively mitigate the damage caused by salt stress to plants is particularly important.It is important to apply additives to alleviate the damage caused by salt stress to plants and improve the plants salt resistance has always been a hot spot for researchersGlycine soja as a good quality forage grass,salt stress severely limits its growth and development.In this study,Glycine soja was used as a test material to study the physiological and photosynthetic responses of Glycine soja under salt stress,and to explore the resistance of Glycine soja to exogenous added silicon(Si),glutamic acid(Glu)and melatonin(MT)The influence of salinity.The main research results are as follows:1.Salt stress has an inhibitory effect on the growth and physiology of Glycine soja Compared with the control,salt stress causes the membrane lipid peroxidation of Glycine soja leaves,resulting in a significant increase in MDA content(P<0.05).At the same time,the relative water content of Glycine soja leaves also decreased significantly(P<0.05).Glycine soja adapt to this salt stress environment by significantly increasing osmotic adjustment substances(Proline,SS,SP content)and antioxidant enzyme activities(P<0.05).In addition,this study also explored the effect of salt stress on the photosynthesis of Glycine soja leaves through transient chlorophyll a fluorescence(PF)and 820 nm light reflection(MR)detection.The results showed that after the salt stress treatment,the Glycine soja chlorophyll Chl a fluorescence induced transient(OJIP)curve and MR/MRo kinetic curve changed significantly.After JIP-test test,it was found that the performance indicators(PIABS,PItotal)and specific energy flux parameters of Glycine soja under salt stress were significantly reduced,while the quantum yield and efficiency parameters were significantly increased(P<0.05)2.Exogenous addition of Si,Glu and MT can effectively alleviate the damage to Glycine soja caused by salt stress.Compared with salt stress alone,exogenous addition of Si,Glu and MT under salt stress effectively increased the content of osmotic adjustment substances and antioxidant enzyme activity of Glycine soja,thereby significantly reducing the content and conductivity value of H2O2 and MDA(P<0.05)At the same time,the addition of Si,Glu and MT can significantly reduce the Na+content in the stems and leaves of Glycine soja,while the K+and Mg2+content increased significantly(P<0.05).The initial fluorescence value Fo of the Chl a fluorescence-induced transient(OJIP)curve also decreases,and the peak FM and initial slope increase(P<0.05),specific energy flux parameters,Y(NPQ),Y(NO),and NPQ values The energy consumption of the PSII reaction center is significantly reduced(P<0.05),while the quantum yield and efficiency,Fv/Fm,ETR,Y(?),qP,qL,Rfd and Fd are significantly increased(P<0.05),thus The maximum photosynthetic efficiency and actual photosynthetic efficiency of Glycine soja leaves are effectively improved.In addition,exogenous addition of Si,Glu and MT can effectively increase the chlorophyll content of Glycine soja.As a result,the restriction of salt stress on the growth of Glycine soja is effectively alleviated,and its plant height,root length and biomass are significantly increasedIn summary,salt stress causes damage to the growth and physiology of Glycine soja,and the exogenous addition of silicon,glutamic acid and melatonin can effectively alleviate the adverse effects of salt stress on Glycine soja.Using the membership function to comprehensively evaluate the relieving ability of three kinds of exogenous additives on Glycine soja under salt stress,it was found that exogenous Si had the best relieving effect on Glycine soja under salt stress,followed by glutamic acid.This provides a theoretical basis for using exogenous silicon to improve the salt tolerance of Glycine soja.