Photosynthesis and Transpiration Characteristics of Four Common Shrub Vegetation in Northeast of China

An experiment was conducted to study the photosynthesis and transpiration characteristics of Forsythia mandshurica,Cerasus tomentosa,Syringa microphylla and Philadelphus schrenkii in Northeast of China by using the Li-Cor 6400 portable photosynthesis system.The correlation analysis among net photosynthetic rate,transpiration rate and their related physiological and ecological factors were made respectively.The results showed that the diurnal change of net photosynthetic rate and transpiration rate of Cerasus tomentosa(Thunb.)Wall.and Syringa microphyllashowed one-peak type.The diurnal change of net photosynthetic rate of Forsythia mandshurica Uyeki showed one-peak type and transpiration rate showed two-peak type,while those of Philadelphus schrenkii Rupr.exhibited a typical bimodal curve and one-peak type.The main physiological factors of net photosynthetic rate and transpiration rate were stomatal conductance and intercellular CO2 concentration.Photosynthetic rate and transpiration rate of 4shrubs were positively correlated with stomatal conductance,and negatively correlated with intercellular CO2 concentration.Photosynthetic rate and transpiration were closely related to photosynthetically active radiation,air CO2 concentration and air relative humidity.Photosynthetically active radiation was the main positive ecology factor affecting photosynthesis,while intercellular CO2 concentration and air CO2 concentration were the main negative factors.