中文摘要：

为了研究珙桐叶片光合特征及其与环境因子的相互关系,对珙桐的引种驯化及资源保护提供重要的理论依据,采用美国产Li-6400型便携式光合测定系统,测定了珙桐叶片的光合作用日变化以及光响应曲线。结果表明：珙桐叶片的表观光量子速率0.09μmol/mol,暗呼吸速率1.31μmol.m-2.s-1,光补偿点22.01μmol.m-2.s-1,光饱和点465.18μmol.m-2.s-1;珙桐叶片的净光合速率、蒸腾速率和气孔导度的日变化曲线均呈双峰曲线,存在明显的＂午休＂现象;珙桐叶片净光合速率与气孔导度、蒸腾速率呈极显著正相关;气孔导度和蒸腾速率是影响珙桐光合速率的生理因子。

英文摘要：

To study the relationship between photosynthetic characteristics and environment factors in leaves of Davidia Involucrate,to provide theoretical basis for introduction and domestication of Davidia Involucrate,The photosynthetic characteristics of Davidia Involucrate seedlings were studied with a Li-6400（LI-COR.Lincoln,Nebraska,USA） portable photosynthesis system.The results showed that： apparent quantum yield in leaves was 0.09 μmol·mol-1.The dark respiration rate was 1.31 μmol·m-2·s-1.The light compensation point of photosynthesis was 20.01 μmol·m-2·s-1.The light saturation point was 465.18 μmol·m-2·s-1;The diurnal variation of the net photosynthetic rate,the transpiration rate and the stomata conductance varied in a double peaks curve,There was obvious midday depression of photosynthesis,because of the non stomata limitation;the net photosynthetic rate was significantly positively correlated with the transpiration rate and the stomata conductance,the transpiration rate and the stomata conductance are major physiological factors influencing diurnal changes of net photosynthetic rate.