Study on the Photosynthetic Dynamic and the Response to CO₂ of Mahonia fortunei in the Limestone Zone in Chongqing

The photosynthetic characteristics of a shrub,Mahonia fortunei in the limestone area of Chongqing was studied by CI-310 portable photosynthesis system.The results showed as follows: The diurnal variation of Pn and Gs of M.fortunei was "twin-peaked" curves and appeared "photosynthetic depressed" in the noon that related to non-stomatal restriction factor.The diurnal variation of E was "singled-peaked" curve and that of WUE looked like an "L".The seasonal changes of Pn,E and Gs were all "twin-peaked" curves,but WUE appeared a "W" curve.In order to grow well in limestone area M.fortunei took a way of "low photosynthesis,low transpiration and high water use efficiency".The experiment of response of Pn to CO₂ indicated that Pn increased with the rise of CO₂ and CO₂ compensation point was 90 μmol·mol^-1 and CE was 0.0125,which caused that M.fortunei had slow grow speed.