【摘要】 为明确大气CO₂浓度升高对施盐处理下银叶树光合特性的影响,利用LI 6800便携式光合测定仪测定施盐处理60 d后银叶树幼苗叶片在不同CO₂浓度（400、600和800μmol/mol）下对光的响应曲线以及CO₂响应曲线。结果表明:1)随着CO₂浓度的升高,银叶树幼苗叶片净光合速率（P_n）、最大净光合速率(P_nmax)、表观量子利用效率（AQY）、光饱和点（LSP）、暗呼吸速率（R_d）、水分利用效率（WUE）和胞间CO₂浓度（C_i）均呈上升趋势,而光补偿点（LCP）、蒸腾速率（T_r）和气孔导度（G_s）则呈下降趋势;2)同一CO₂浓度下,施盐处理下银叶树幼苗叶片P_n、P_nmax、AQY、LSP、LCP、R_d、T_r和G_s均低于对照处理,而WUE和C_i则差异不大;3)随着光合有效辐射（PAR）的增加,银叶树幼苗叶片T_r和G_s呈增加的趋势,WUE先增加后缓慢减小,C_i则先直线下降,之后达到稳定状态;4)施盐处理下银叶树幼苗叶片最大羧化速率(V_cmax)、最大电子传递速率(J_max)、磷酸丙糖利用效率（TPU）、P_nmax、初始羧化效率（CE）和光呼吸速率（R_P）均低于对照处理,而CO₂饱和点(C_isat)和CO₂补偿点（Γ）则更高;5)随着CO₂浓度的增加,银叶树幼苗叶片T_r和G_s大致呈下降的趋势,WUE和C_i则呈直线增加的趋势。本研究结果说明CO₂浓度的增加对银叶树幼苗的生长有促进作用,而施盐处理则抑制其生长。更多还原

【Abstract】 [Background]Heritiera littoralis is an endangered semi mangrove tree species.Recently,the community structure,biological characteristics,medicinal value,fruit characteristics and germination technology and genetic diversity of H.littoralis have mainly been analyzed by scholars,but the high CO₂concentration on photosynthetic characteristics in the leaves of H.littoralis seedlings under salinity treatment has been less investigated.It is important to explore the effects of elevated CO₂on photosynthesis characteristics in H.littoralis under salinity treatment,which is essential to provide references for the application of H.littoralis to the vegetation restoration in coastal areas.[Methods]1-year-old H.littoralis seedlings were used for comparison test in the green house of Guangdong Academy of Forestry in Guangzhou.Salinity treatment was simulated using salt solution concentration gradients of 0（CK） and 2.5%（salinity treatment） at different CO₂concentration （400,600 and 800μmol/mol）.There were 16 repeats in each concentration,thus totally 96 pots.After 60 days,photosynthetic physiological parameters were measured by LI-6800 photosynthesis instrument （LI-COR,USA）.Then modified rectangular hyperbolic model was adopted to fit the photosynthesis light-response curves at different CO₂concentration and CO₂response curves of H.littoralis leaves of salinity treatment.[Results]1) After the experiment treatment,with the increase of CO₂concentration,net photosynthetic rate （P_n）,maximum net photosynthetic rate (P_nmax),apparent quantum yield （AQY）,light saturation point （LSP）,dark respiration rate （R_d）,water use efficiency （WUE） and intercellular CO₂concentration （C_i） in the leaves of H.littoralis seedlings increased,while light compensation point（LCP）,transpiration rate （T_r） and stomatal conductance （G_s） decreased.2) At the same CO₂concentration,P_n,P_nmax,AQY,LSP,LCP,R_d,T_rand G_sunder salinity treatment were lower than those under control,while the difference of WUE and C_ibetween the two treatment groups were not significant.3) With the increase of photosynthetic active radiation （PAR）,T_rand G_sshowed an increasing trend,WUE increased first and then decreased slowly,while C_idecreased linearly and then reached a steady state.4) Maximum carboxylation rate (V_cmax),maximum rate of electron transport (J_max),triosephosphate utilization efficiency （TPU）,P_nmax,initial carboxylation efficiency （CE） and photorespiration rate （R_P） under salinity treatment were lower than those under control,while CO₂saturation point (C_isat)and CO₂compensation point （Γ） showed an opposite trend.5) T_rand G_sdecreased with the increase of CO₂concentration,while WUE and C_ipresented linear increase.[Conclusions]The increase of CO₂concentration promotes the increase of P_n,P_nmax,AQY,LSP,R_d,WUE and C_i.Higher CO₂concentration in the environment can increase the photosynthetic efficiency of H.littoralis leaves,especially when the light intensity is high.The salt stress can reduce the photosynthetic rate of H.littoralis leaves significantly.The results of this research indicate that the increase of CO₂concentration promotes the growth of H.littoralis seedling,while salinity treatment inhibits its growth.更多还原