Effect of salt stress on photosynthetic and chlorophyll fluorescent characteristics in Alnus formosana seedlings

The one-year seedlings under 0.1%,0.2%,0.4%,0.6% and 0(CK) of NaCl stress were investigated to explore the effect of salt stress on photosynthetic characteristics and chlorophyll fluorescence parameters in Alnus formosana.The results were indicated that the value of intercellular CO2 concentrations(Ci) went up while the net photosynthetic rate(Pn),stomatal conductance(Gs),transpiration rate(Tr) gradually went down.And the potential photochemical activity of photosystem Ⅱ(Fv/F0),the maximal photochemical efficiency of photosystem Ⅱ(Fv/Fm) was dropped and non photochemical quenching coefficient(NPQ) was ascend under salt stress.The relationship between the initial fluorescence yield(F0) and Fv/F0,Fv/Fm,was significantly difference.Also there was extremely significantly difference between F0 and the photochemical quantum yield of photosystem Ⅱ(Yield),the photochemical quenching coefficient(qP).Among the parameters,including Fv/F0,Fv/Fm,Yield,was shown very significant related.During the period of salt stress,the main cause of Pn reduced was not stomatal limitation.It was relieved the effect of stress through enhancing the heat dissipation in A.formosana seedlings.Two months later,0.1% salt stress expressed much stronger capacity of photosynthetic than CK.