不同种源地北美鹅掌楸光合特性研究

以3个种源地北美鹅掌楸无性系为试验材料，利用LI-6400XT便携式光合测定系统，研究了净光合速率日变化及对有效光辐射和CO₂的响应等光合特性。结果表明，宾夕法尼亚种源和俄亥俄种源北美鹅掌楸的P_n日变化曲线呈双峰型，具有明显的午休现象，峰值出现在10:00和14:00，纽约种源北美鹅掌楸不具有明显的午休现象。光响应曲线和CO₂响应曲线数据分析表明，纽约种源北美鹅掌楸光饱和点（1 180.4 μmol·m^-2·s^-1）和光补偿点（10.27 μmol·m^-2·s^-1）均高于另外2个种源。这种趋势也同样适用于CO₂饱和点（1 595.0 μmol·m^-2·s^-1）和CO₂补偿点（107.5 μmol·m^-2·s^-1）。在北方低光照环境下，纽约种源较高的光补偿点和CO₂补偿点，不利于有机物的积累，宾夕法尼亚种源对光照和CO₂要求较低，更适合北方环境。

Photosynthetic Characteristics of Liriodendron tulipifera from Different Provenances

Diurnal changes of photosynthesis, light response curves and CO₂ response curves of the Liriodendron tulipifera clones which introduced from three different provenances were researched by LI-6400XT．The results showed that the diurnal changes of the net photosynthetic rate of both Pennsylvania’s and Ohio’s clones displayed twin peaks with an obvious midday depression. The peaks appeared in 10:00 and 14:00. However, midday depression disappeared in the New York’s clone. The analysis of light response and CO₂ response curves showed that both the light saturation point (1 180.4 μmol·m^-2·s^-1) and the light compensation point (10.27 μmol·m^-2·s^-1) of New York’s clone were higher than those of the Pennsylvania’s and Ohio’s clones. This trend was also applicable to the CO₂ (1 595.0 μmol·m^-2·s^-1) saturation point and CO₂ compensation point (107.5μmol·m^-2·s^-1). Under the low light conditions in northern China , light compensation point and CO₂ compensation point were higher in New York provenance, so it was not conducive to the accumulation of organic matter. Pennsylvania’s provenance was more suitable for the northern environment because it needs little light and CO₂.