采用LI-6400 型便携式光合测定仪对潜在能源植物曼陀罗(Datura stramonium L.)在6 月份至9 月份的光合特性指标(净光合速率、光合有效辐射强度和气孔导度)的日变化以及净光合速率和叶绿素含量的月平均值变化进行了研究,并采用非直角双曲线对曼陀罗叶片净光合速率的光响应曲线和CO₂ 响应曲线进行了拟合。结果表明:实验期间(6 月份至9 月份),光合有效辐射强度和曼陀罗叶片净光合速率的日变化均呈“单峰型”,峰值出现在11:00 左右;7 月份的净光合速率峰值最高,为19. 01 μmol·m^-2 ·s^-1 ;气孔导度日变化呈“双峰型”,最大峰值和次峰值分别出现在12:00 和14:00。不同月份的净光合速率月平均值有极显著差异(P<0. 01),其中7 月份的净光合速率月平均值最大,为9. 41 μmol·m^-2 ·s^-1 ;不同月份叶绿素的月平均含量变化与净光合速率月平均值的变化相似,7 月份叶绿素的月平均含量也最高,但叶绿素a、b 及总叶绿素月平均含量有一定差异。曼陀罗叶片净光合速率的光响应曲线和CO₂ 响应曲线相似,在光合有效辐射强度和CO₂ 浓度较低的条件下呈线性升高,至饱和点后缓慢升高并趋于稳定;曼陀罗叶片的光补偿点为22. 42 μmol·m^-2 ·s^-1 ,光饱和点为689. 26 μmol·m^-2 ·s^-1 ;CO₂ 补偿点为74. 06 μmol·mol^-1 ,CO₂ 饱和点为1 331. 97 μmol·mol^-1 。研究结果说明,曼陀罗为具有一定耐阴能力的阳性植物,但CO₂ 同化能力较弱。

From June to September, daily change of photosynthetic characteristics indexes (including net photosynthetic rate, photosynthetically active radiation intensity and stomatal conductance) and monthly average change of net photosynthetic rate and chlorophyll content of potential energy plant Datura stramonium L. were measured with LI-6400 portable photosynthesis system, and light and CO₂ response curves of net photosynthetic rate of the species were fitted with non-rectangular hyperbola. The results show that during experimental period (from June to September), daily change of photosynthetically active radiation intensity and net photosynthetic rate of D. stramonium leaves is “single peak type”with a peak occurring at about 11:00, and the peak value of net photosynthetic rate in July is the highest with a value of 19. 01 μmol·m^-2 ·s^-1. Daily change of stomatal conductance is “double peak type”, the highest and secondary peak values appear at 12:00 and 14:00, respectively. Monthly average of net photosynthetic rate among different months has extremely significant differences (P<0. 01), in which that in July is the highest with a value of 9. 41 μmol·m^-2 ·s^-1. Change of monthly average of chlorophyll content is similar to that of net photosynthetic rate among different months, and monthly average of chlorophyll content in July is also the highest, but monthly average of Chla, Chlb and total chlorophyll contents has a certain difference. Light and CO₂ response curves of net photosynthetic rate of D. stramonium leaves are similar, both of them increase linearly under low photosynthetically active radiation intensity and CO₂ concentration conditions, then increase slowly after reaching of a saturation point and tend to steady at last. Light compensation point and light saturation point of D. stramonium are 22. 42 and 689. 26 μmol·m^-2 ·s^-1, respectively, while CO₂ compensation point and CO₂ saturation point of the species are 74. 06 and 1 331. 97 μmol·mol^-1, respectively. It is concluded that D. stramonium is the heliophyte with a certain shade tolerance, but its CO₂ assimilation ability is weaker.