Physiological Response Of Broussonetia Papyrifera Seedlings And Broussonetia Papyrifera L. Seedlings To Saline-alkali Stress

At present,the global ecological environment and agricultural production are facing a very serious ecological problem-soil salinity stress.Broussonetia papyrifera(Broussonetia papyrifera)is widely distributed in most areas of China.It has excellent characteristics of barren,drought and saline-alkali tolerance.It is one of the ideal pioneer tree species for barren hill greening and saline-alkali land greening.Broussonetia papyrifera L.(Broussonetia papyrifera L.)is a structural tree cultivar developed by Institute of Botany,Chinese Academy of Sciences through space breeding technology,which has high economic value,strong adaptability,drought and salinity tolerance.Two kinds of single salts(Na2SO4,NaHCO3)were studied.Effects of physiological indexes of tree seedlings.The physiological adaptation characteristics of photosynthetic system,chlorophyll fluorescence system,antioxidant system and osmotic adjustment substance to single salt of Broussonetia papyrifera seedlings and Broussonetia papyrifera L.seedlings were discussed.The dominant factors of salt-alkali stress on the two tree seedlings and the salt tolerance of the two tree seedlings were determined by statistical methods.The main findings are as follows:1.Correlation analysis between photosynthesis and fluorescence index indicated that chlorophyll content and Pn,Gs,Ci and Tr were reliable indicators for measuring the salt and alkali resistance of the two tree species,while the chlorophyll fluorescence index was used for the two tree species.2.With the increase of salt concentration,the photosynthesis of the two tree species was significantly inhibited,and the stomatal limitation factor was the main limiting factor.Fo,Fm is"increasing-declining" trend,Fv/Fm,Fv/Fo shows the trend.Salt stress inhibited the function of PSII in the two mulberry seedlings,hindered the transmission of photosynthetic electrons and inhibited photosynthesis of plants.The photochemical properties of the two mulberry seedlings under Na2SO4 stress were better than those under NaHCO3 stress.The photochemical properties of Broussonetia papyrifera L seedlings were better than those of Broussonetia papyrifera seedlings.3.Under the treatment of Na2SO4 stress and NaHCO3 stress,the chlorophyll content of the Broussonetia papyrifera seedlings and Broussonetia papyrifera L.seedlings showed a "decline-rise"trend.The MDA content showed a change pattern of "rise-lower-rise".Both SOD and POD activities showed a trend of "rise-down".Pro showed an increasing trend,and soluble sugar showed a trend of"rise-down".4.The Broussonetia papyrifera plays a leading role in POD enzyme activity under Na2SO4 stress treatment.Under the treatment of Na2SO4 stress,the SOD activity of Broussonetia papyrifera L.played a leading role.Under NaHCO3 stress treatment,SOD and POD alternately function to scavenge reactive oxygen species,and the POD enzyme activity plays a leading role,inhibiting the increase of MDA content.From the perspective of the variation of the three indicators,the seedlings of the Broussonetia papyrifera L.are more sensitive to salt-alkali stress than the seedlings of the Broussonetia papyrifera.5.In the process of osmotic adjustment,Broussonetia papyrifera seedlings and Broussonetia papyrifera L.seedlings are mainly composed of free proline accumulation and soluble sugar synthesis to exert their osmotic adjustment.To alleviate the damage caused by neutral salt Na2SO4 stress and alkaline salt NaHCO3 stress.However,they did not coordinate with each other to reduce the salt-alkali stress damage to maintain the normal physiological metabolism of the plants.If the salt tolerance of a tree species is evaluated by the amount of Pro under salt stress,it can be considered that the Broussonetiapapyriferaseedlings>the Broussnetia papyrifera L.seedlings.