聚丙烯酰胺和CO2浓度变化对胡杨叶片光合和水分利用效率的影响

采用盆栽实验研究了不同聚丙烯酰胺用量下较短时间内CO2浓度升高对1年生胡杨叶片光合和水分和用效率的影响。结果表明：（1）随着聚丙烯酰胺用量的减少，土壤水吸力上升，干旱胁迫加重。叶片水势、净光合速率（Pn）、水分利用效率（WUE）、气孔导度（Gs）、蒸腾速率（Tr）随着干旱胁迫的加重而降低，胞间CO2浓度（Ci）则呈上升趋势。（2）随着CO2浓度的升高，各处理的胡杨叶片Pn、WUE、Ci上升，Tr、Gs下降。由此说明：CO2浓度升高对胡杨叶片Pn和WUE的促进作用在一定程度上能缓解干旱胁迫作用；聚丙烯酰胺用量大时，CO2浓度升高对胡杨Pn的促进作用较好；随着外界CO2浓度的升高，气孔关闭，蒸腾速率降低，从而增加了胡杨WUE，这将加强胡杨的耐旱能力。

Studies on Effects of Polyacrylamide and CO2 Concentration Variations on Photosynthesis and Water Use Efficiency of Populus euphratica

Experiment was conducted with pot-cultured seedlings of Populus euphratica for studying the enrichment of CO2 eoncentration＇s effect on the photosynthesis and water use efficiency（WUE） under different polyacrylamide content. The results are as follows ： （ 1 ） With the polyacrylamide content decreased, the soil water suction increased, then drought stress developed. With the water stress increased, leaf water potential, net photosynthetic rate （Pn）, water use efficiency, stomatal conductance （Gs） and transpiration rate （Tr） were reduced, the intercellular CO2 concentration（Ci） was increased. （2）With the CO2 concentration elevated,the Pn, WUE and Ci increased, but the Tr and Gs decreased. The results we have concluded showed that To some extent the influence of drought stress to Pn and WUE was relieved by the enrichment of CO2 concentration;The effects of CO2 concentration enrichment on Pn depend on polyacrylamide content, when it increased, the plants benefited more; When the CO2 concentration enhanced, the stomata closed and the Tr decreased, so that the WUE increased, which could strengthen the tolerance of Populus euphratica to the drought stress.