Diurnal Variation of Eco-physiological and Photosynthetic Characteristics of Reynoutria japonica

The studies on diurnal variation of eco-physiological characteristics of photosynthesis of five Reynoutria japonica materials and their environmental factors were measured with the Li-6400 portable photosynthetic system.The results showed as following:(1)The diurnal variation of net photosynthetic rate(Pn) presented a single-peak curve,and the maximum value was 15.0 μmol CO2·m-2·s-1,which occurred at 9:00;(2)The peak values of water deficit,stomatal conductance and transpiration rate(Tr) appeared at the same time at 13:00.Intercellular CO2 concentration(Ci) didn't decrease with the dropping of stomatal conductance and the mainly controlling factor of photosynthetic rate was non-stomatal limitation.(3)The diurnal variation of the five tested materials showed almost alike tendency,and the Pn of the tissue-cultured plantlets that were cultivated in the land showed the highest,while Guizhou Kaili the lowest.The variation of photosynthetic characteristic parameters was greatly affected by photosynthetic active radiation,which was critical to Pn(r=0.534**).While the environmental factors affected the Pn mainly by Tr,leaf water deficit and air temperature.