盐胁迫对台湾桤木幼苗光合作用和荧光特性的影响

为探讨台湾桤木的耐盐机制,以1年生台湾桤木实生幼苗为试验材料,采用盆栽加盐的方式模拟盐胁迫,设置0.1%、0.2%、0.4%、0.6%及0(CK)5个盐分梯度,研究台湾桤木幼苗在盐胁迫下的光合作用和荧光特性。结果表明,盐胁迫使叶绿素含量降低,净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)逐渐降低,而胞间CO2浓度(Ci)增大,各处理间差异极显著,主要光合参数Pn、Gs、Tr、Ci两两之间相关性极显著;PSⅡ潜在光化学活性(Fv/F0)、PSⅡ最大光化学效率(Fv/Fm)随着盐胁迫逐渐下降,非光化学淬灭系数(NPQ)增大,初始荧光(F0)与Fv/F0、Fv/Fm相关性显著,F0与PSⅡ光化学量子产额(Yield)、光化学淬灭系数(qP)相关性极显著,Fv/F0与Fv/Fm、Yield两两之间相关关系极显著。因此认为,盐胁迫期间Pn降低主要由于非气孔限制因素;桤木幼苗通过增强热耗散的方式来缓解逆境对光合作用的影响;胁迫2个月后,低盐胁迫(0.1%)具有比CK更大的光合能力。

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.