水分胁迫对大丽花光合作用、蒸腾和气孔导度的影响

以大丽花品种‘粉西施’盆栽扦插苗为试材，研究了不同程度水分胁迫及复水对大丽花品种粉西施叶片光合作用、蒸腾和气孔导度的影响。结果表明：随着水分胁迫程度的加深和胁迫时间的延长，大丽花叶片的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和水分利用率(WUE)下降，胞间CO2浓度(Ci)先下降后上升，气孔限制值Ls先升高后下降。轻度和中度水分胁迫下，气孔限制是Pn降低的主要原因；重度水分胁迫下，非气孔限制是Pn降低的主要原因。重度胁迫更早对大丽花叶片造成伤害，重度胁迫下复水后光合指标难以恢复。

Effects of Water Stress on Photosynthesis, Transpiration and Stomatal conductance in Dahlia Leaves

The effects of different levels of water stress and rewatering on leaf transpiration,photosynthesis and stomatal conductance ofdahlia‘Fenxishi’plant were studied.The photosynthetic available radiation （PAR）,transpiration rate （Tr）,net photosynthetic rate （Pn）,stomatal conductance （Gs） and intercellular CO2 concentration （Ci） ofdahlia‘Fen xishi’were tested by CIRAS-2 portable type photosystem which produced by PP-Systems company in England.The results showed that transpiration rate （Tr）,net photosynthetic rate （Pn）,stomatal conductance （Gs） and water using efficiency （WUE） decreased with the increasing of water stress and the lasting of time.Intercellular CO2 concentration （Ci） decreased first and then increased.Ci increased at the 12th day on light and moderate stress while increased at the 9th day on serious stress.Stomatal limitation value （Ls） increased first and then decreased.Ls decreased at the 12th day on light and moderate stress while decreased at the 9th day on serious stress.The reasons of Pn indahlia leaves decreased were stomatal and nonstomatal limitation respectively in light and severe water stresses.After rewatering,the photosynthesis characteristics can not recover on the serious stress which did damage todahlia leaves earlier than other stresses.