Abstract: To evaluate the environmental adaptability of Saraca griffithia, the diurnal variation of its photosynthetic parameters and environmental impact factors was measured using Li-6400XT portable photosynthetic analyzer. The results showed that the daily variation of net photosynthetic rate (Pn) of S. griffithia was a bimodal pattern, with a clear "midday rest" phenomenon, which was determined by non stomatal limiting factors. There was no statistically significant correlation between the Pn and environmental factors of S. griffithia, while environmental factors such as effective photosynthetic radiation (PAR), atmospheric temperature (ta), relative humidity (RH), and atmospheric CO2 concentration (Ca) jointly affect the photosynthesis, rather than a single factor playing a dominant role. The transpiration rate (Tr) was significantly positively correlated with PAR and ta, while the stomatal conductance (Gs) was significantly negatively correlated with PAR and ta, indicating that environmental impact factors adapt to strong light and high temperature through self-regulation.

Key words: Saraca griffithia; net photosynthetic rate; transpiration rate; ecological adaptability

摘要： 为研究云南无忧花Saraca griffithiana的环境适应性，利用Li-6400XT便携式光合测定仪测定其光合参数日变化及对环境因子的响应。结果表明，云南无忧花净光合速率(Pn)的日变化为双峰型，有明显“午休”现象，该现象由非气孔限制因素所决定。有效光合辐射(PAR)、大气温度(ta)、空气相对湿度(RH)、大气CO2浓度(Ca)等环境因子共同影响云南无忧花的光合作用，而非其中单一因子起主导作用。云南无忧花Pn与PAR等4个环境因子的相关性不显著。蒸腾速率(Tr)与PAR、ta呈极显著正相关；气孔导度(Gs)与PAR、ta呈极显著负相关。表明云南无忧花通过自身调节以适应强光和高温等环境变化。研究结果为云南无忧花的栽培、种质资源保护和推广应用提供参考。

关键词: 云南无忧花；净光合速率；蒸腾速率；生态适应性