大气CO2浓度升高对绿豆叶片光合作用及叶绿素荧光参数的影响

利用FACE系统在大田条件下通过盆栽试验研究了大气CO₂浓度升高\CO₂浓度平均为（550±60) μmol·mol^-1\]对绿豆叶片光合生理和叶绿素荧光参数的影响.结果表明： 与对照\CO₂浓度平均为（389±40）μmol·mol^-1左右\]相比，大气CO₂浓度升高使花荚期绿豆叶片净光合速率(P_n)和胞间CO₂浓度(C_i)分别升高11.7%和9.8%，气孔导度(G_s)和蒸腾速率(T_r)分别下降32.0%和24.6%, 水分利用效率(WUE)提高83.5%；在蕾期，CO₂浓度升高对绿豆叶片叶绿素初始荧光(F_o)、最大荧光（F_m）、可变荧光（F_v）、F_v/F_m和F_v/F_o没有显著影响；在鼓粒期，CO₂浓度升高使绿豆叶片F_o增加19.1%，F_m和F_v分别下降9.0%和14.3%，F_v/F_o和F_v/F_m分别下降25.8%和6.2%.表明大气CO₂浓度升高可能使绿豆生长后期光系统Ⅱ反应中心结构受到破坏，叶片的光合能力下降.

Effects of elevated atmospheric CO2 concentration on mung bean leaf photosynthesis and chlorophyll fluorescence parameters.

By using free air CO₂ enrichment (FACE) system, a pot experiment under field condition was conducted to study the effects of elevated CO₂ concentration (550±60 μmol·mol^-1) on the leaf photosynthesis and chlorophyll fluorescence parameters of mung bean. Comparing with the control (CO₂ concentration averagely 389±40 μmol·mol^-1),elevated CO₂ concentration increased the leaf intercellular CO₂ concentration (C_i) and net photosynthesis rate (P_n) at flowering and pod growth stage by 9.8% and 11.7%, decreased the stomatic conductance (G_s) and transpiration rate (T_r) by 32.0% and 24.6%, respectively, and increased the water use efficiency (WUE) by 83.5%.Elevated CO₂ concentration had lesser effects on the minimal fluorescence (F_o), maximal fluorescence (F_m), variable fluorescence (F_v), ratio of variable fluorescence to minimal fluorescence (F_v/F_o), and ratio of variable fluorescence to maximal fluorescence (F_v/F_m) at bud stage, but increased the F_o at pod filling stage by 19.1% and decreased the F_m, F_v, F_v/F_o, and F_v/F_m by 9.0%, 14.3%, 25.8%, and 6.2%, respectively. These results suggested that elevated CO₂ concentration could damage the structure of leaf photosystemⅡ and consequently decrease the leaf photosynthetic capacity in the late growth phase of mung bean.