Photosynthetic Characters and Impact Factors of Three Flowering Shrubs

To quantize and study the ability of carbon fixation and transpiration in urban forest,diurnal and seasonal changes of photosynthetic rate in different seasons of main shrub species(Syringa oblata,Forsythia suspensa and Prunus triloba) in Shenyang was studied using LI-6400 IR gas analyzer(IRGA),and using statistical method of multinomial regression,the related equation on net photosynthetic rate and environmental factors were also constructed.The results showed that the diurnal changes of photosynthetic rate of Syringa oblata and Prunus triloba in spring and summer presented double peak curves,while that of Forsythia suspensa was single peak curve;the diurnal changes of photosynthetic rate of the three shrubs in autumn were single peak curve.The seasonal changes of net photosynthetic rate of Syringa oblata was: summerautumnspring and that of Prunus triloba and Forsythia Suspensa in spring and summer was higher than in autumn.The photosynthetic rate in spring and summer were mainly affected by photosynthetic active radiation and stomata conductance,and the direct factor of the photosynthetic rate in autumn was temperature.