Preliminary Study on the Diurnal Variation of Emmenopterys henryi,a Rare Species

The diurnal variation of photosynthesis of Emmenopterys henryi young tree under natural conditions was studied.The results were as follows: In summer fine days,the curves of diurnal variation of net photosynthetic speed had two peaks,which showed an obvious decline of photosynthetic efficiency at noon.It was principally caused by non-stomatal limitation.The most excellent equation of the diurnal variation of net photosynthetic speed was attained by the method of stepwise multiple-regression as follows:A=-137.5217-0.0076Q+0.2148Ca+0.2294RH-3.7208Ta+5.0365Tl.The response tests of light and CO2 indicated that the light inhibition under strong light was the key cause for the decline of photosynthetic efficiency at noon.