滨海滩涂洋白蜡的光合特性

Photosynthetic characteristics of Fraxinus pennsylvanica in coastal beach,Shanghai

洋白蜡作为引进种,已在我国广泛种植。以上海南汇滨海森林公园内5年生洋白蜡树种为研究对象,系统研究了其叶片光响应曲线和光合作用日变化。结果发现,洋白蜡光补偿点为32.69μmol/(m2.s),光饱和点为948.55μmol/(m2.s),暗呼吸速率为1.06μmol/(m2.s);净光合速率日变化呈现双峰曲线,最大值为(11.37±2.14)μmol/(m2.s),经相关性分析发现净光合速率与气孔导度、光合有效辐射间存在显著的正相关性;蒸腾速率日变化也呈现双峰曲线,并与气孔导度、温度、大气CO2浓度、光合有效辐射间存在显著的正相关,与相对湿度存在显著的负相关。

Fraxinus pennsylvanica,an introduced species,was widely planted in China.The light response curve and daily variation of photosynthesis of 5 years old Fraxinus pennsylvanica plants were determined in a coastal forest park,Nanhui,Shanghai.The results showed that light compensation point,light saturation point and dark respiration were 32.69 μmol/（m2·s）,948.55 μmol/（m2·s）and 1.06 μmol/（m2·s）respectively.The daily variation of net photosynthesis rate（Pn） showed a mid-depression,with the maximum Pn of 11.37±2.14 μmol/（m2·s）,and significant positive correlations were found between Pn and stomatal conductivity（Co）,photosynthetic active radiation.The daily dynamic of transpiration rate（Tr） was same to Pn,and showed significant positive relationships to Co,temperature（T）,atmospheric CO2 concentration（Ca） and PAR,and negative correlation to relative humidity.