Abstract: By the way of full of the airtight system , the Pn and Rd of different positions of leaves of ‘Red Globe’grape plantlet s were determined by Combined Inf rared Gas Analysis System. The results showed that grape plantlets have a certain ability of photosynthesis. The leaves on the higher position have
the lower value of net photosynthesis rate (Pn) but have the higher respiratory rate (Rd) . The increased concent ration of CO₂ can enhance the rate of net photosynthesis , meanwhile , rest rain respiration , and obviously , the Pn was improved due to the increasing of light intensity. With the rise of temperature , all the Rd of leaves tended to increase , but the Pn increased first and then decreased. Compensation point of CO₂ of leaves in different leaf positions increased with the temperature increasing.

Key words: Grape, Plantlet, Leaf position, Photosythetic, Respiratory