高浓度CO2对不同水分条件下枇杷生理的影响

 在近似大气的低CO₂浓度(400 μmol·mol^-1 )和高CO₂浓度(700 μmol·mol^-1)的两个自制的开顶式生长室内，研究分析了水分胁迫对2年生‘大红袍’枇杷(Eriobotrya japonica Lindl.)叶片的光合作用、叶绿素荧光及抗氧化酶活性等生理变化。结果表明，高CO₂浓度对不同水分状态下的枇杷叶片光合速率(Pn)均有明显的促进作用，使枇杷叶片荧光参数Fv／Fm和Fv／Fo值及PSII明显提高；而在水分胁迫时，高CO₂浓度使枇杷叶片荧光参数Fv／Fm和Fv／Fo值及 II下降幅度明显减少；高CO₂浓度也使SOD、POD及CAT酶活性显著提高，但在水分胁迫时，高CO₂浓度下的SOD、POD及CA T酶活性上升幅度明显较小，膜脂过氧化水平的上升幅度也较小，可见CO₂浓度升高对于水分胁迫所造成的氧化损伤有一定的缓解作用。

Physiological Effects of Elevated CO2 on Loquat Trees(Eriobotrya japonica Lindl.)under Water Stress

Loquat trees(Eriobotrya japonica Lindl．)grown in two open-top growth chambers at CO₂ concentrations of 400 μmol·mol^-1 and 700 μmol·mol^-1 were used to study the effects of elevated atmospheric CO₂ ，concentration and water stress on photosynthesis．chlorophyll fluorescence and acting of an tioxidative enzymes in leaves．The results showed that elevated atmospheric CO₂ concentration(700 μmol·mol^-1) significantly enhanced the photosynthesis under various levels of water stress． Furthermore，under high CO₂ condition, the values of Fv/Fm ， Fv／Fo and PSⅡ were also higher than at normal atmospheric CO₂ ，concentration，but the diference between the aterstressedplants and well—watered plants was not significant． In addition， elevated atm ospheric CO₂ concentration considerably jncreased the ach vities of SOD， POD an d CAT． Such jnerease， however， was farless significan t liBder water stress condition．The MDA content also showed less increase under the latter condition． The results indicate that high CO₂ concentration seems to have ameliorating effect on drought—induced oxidative damage．