大米草对CO2浓度的光合和蒸腾响应

以大米草（Spartina anglica Hubbard）为材料，研究在不同CO2浓度下其净光合速率（Pn）、蒸腾速率（Tr）、胞间CO2浓度（Ci）、气孔导度（Gs）、叶面饱和蒸气压亏缺（Vpdt）以及水分利用效率（WUE）的变化。结果表明，CO2浓度从50μmol·mol^-1增至1000μmol·mol^-1的过程中，大米草Pn、Ci、Vpdl和WUE逐渐增大，Gs和Tr逐渐下降。低于环境CO2浓度范围内时，大米草对CO2浓度的升高比较敏感，反之则不明显。WUE和Tr对CO2浓度升高的响应极显著（P〈0．01）。CO2浓度升高能够明显降低单位面积叶片的蒸腾失水，提高光合速率和水分利用效率，增强大米草的竞争优势。

Responses of Photosynthesis and Transpiration Characteristics of Spartina anglica to Different CO2 Concentration

The net photosynthesis （P.）, transpiration （Tr）, intercellular CO2 concentration （Ci）, stomatal conductance （Gs）, vapor pressure deficit at the leaf surface （Vpdl） and WUE of Spartina anglica under different CO2 concentration were measured with Licor-6400 Portable Photosynthesis System. The results indicated that Pn,Ci,Vpdl and WUE increased with CO2 concentration between 50 and 1 000 μmol·mol^-1. But G, and Tr dropped as the CO2 concentration increased. It was concluded than P,, of Spartina anglica was sensitive to CO2 concentration variation which was below than that actual content,it was not sensitive on the contrary. The response of Tr and WUE was most significant to CO2 concentration （P〈0.01）. The increasing of CO2 concentration could significantly decrease the transpiration,increase the photosynthetic rate,the utilization rate of water as well as the competitive advantage of Spartina anglica.