水稻叶片光合作用对开放式空气CO2浓度增高(FACE)的响应与适应

利用便携式光合气体分析系统 (LI 6 4 0 0 ) ,比较测定了高CO2 浓度 (FACE ,free airCO2 enrich ment)和普通空气CO2 浓度下生长的水稻叶片的净光合速率、水分利用率、表观量子效率和RuBP羧化效率等光合参数 .在各自生长CO2 浓度 (380vs 5 80 μmol·mol-1)下测定时 ,高CO2 浓度 (5 80 μmol·mol-1)下生长的水稻叶片的净光合速率、碳同化的表观量子效率和水分利用率明显高于普通空气 (380 μmol·mol-1)下生长的水稻叶片 .但是 ,随着FACE处理时间的延长 ,高CO2 浓度对净光合速率的促进作用逐渐减小 .在相同CO2 浓度下测定时 ,FACE条件下生长的水稻叶片净光合速率和羧化效率明显比普通空气下生长的对照低 .尽管高CO2 浓度下生长的水稻叶片的气孔导度明显低于普通空气中生长的水稻叶片 ,但两者胞间CO2 浓度差异不显著 ,因此高CO2 浓度下生长的水稻叶片光合下调似乎不是由气孔导度降低造成的 .

Response and acclimation of photosynthesis in rice leaves to free-air CO2 enrichment (FACE)

The net photosynthetic rate (Pn), water use efficiency (WUE), and apparent quantum yield of carbon assimilation of rice leaves were boserved contrastively under ambient air (380 mumol.mol-1 CO2) and FACE (580 mumol.mol-1CO2). The results showed that the observed index under FACE were significantly higher than those under ambient air. Nevertheless, along with the time of high CO2 treatment prolonged, the enhancement effect of high CO2 on net photosynthetic rate declined gradually. At the same CO2 concentration, Pn and carboxylation efficiency (CE) in rice leaves under FACE were lower than those under ambient air. Although the stomatal conductances in FACE leaves was obviously lower than that in ambient leaves, their intercellular CO2 concentrations were not significantly different, which implied that the photosynthetic down-regulation in rice leaves grown under FACE was not caused by the decrease of stomatal conductance.