油桐属2个物种的光合特性

采用美国Licor公司生产的Li6400XT便携式光合作用测定系统对三年桐（Vernicia fordii）和千年桐（Vernicia montana）2个油桐物种的光合特性进行了研究。试验结果表明：千年桐的光合速率日变化呈单峰型，无“午休”现象，三年桐净光合速率日变化曲线为双峰型，出现“午休”现象。千年桐日平均净光合速率最高，达到5．67~mol／（m^2·s），物质积累能力较强，三年桐的日平均净光合速率较小，仅为千年桐的55．6％，物质积累能力最弱；在模拟光辐射条件下测定2个物种的光响应曲线，千年桐最大净光合速率较高，三年桐较低，分别为24．24和17．23~mol／（m^2·s）。三年桐光补偿点较低，利用弱光的能力较千年桐强，千年桐光补偿点较高，利用弱光能力较三年桐弱。千年桐的光饱和点较高，利用强光的能力较三年桐强，三年桐光饱和点较低，利用强光的能力较千年桐弱。

Photosynthetic Characteristics of Two Vernicia Species

Photosynthetic characteristics of two Vernicia species, which are Vernicia fordii and Vernicia Montana , were measured by using Li6400 XT from American Licor Company. The results indicated the daily photosynthetic rate change of the Vernicia Montana presented as single summit type without ＂noon break＂ phenomenon, however that of Vernicia fordii presented as double summit type accompanied with ＂noon break＂ phenomenon. The average daily net photosynthetic rate of Vernicla Montana was the higher reached 5.67 lxmol/ （m2 . s） with stronger material accumulating ability, while the rate of Vernicia for dii was weaker accounted for 55.6% of l/ernicia Montana with the lower material accumulating ability. The light response curves of two species were measured under the condition of simulated photosynthetic radiation. The maximum of net photosynthetic rate from Vernicia Montana and Vernicia fordii were 24. 24 and 17.23 umol/ （m^2 . s）, respectively. The light compensation point of Verniciafordii was lower, so the ability of utilizing weak light was stronger. The light saturation point of Vernicia Montana was higher, so the capacity of utilizing strong light was stronger.