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Many photosynthetic characteristics of three plum varieties were studied with a infrared CO2 analyzer.rnResults showed that plums belong to light－loving species,having a relative high light compensation point rn(75～ 80μmol · m-2 · s-1 ), In natural light range from none to 1400μmol · m-2s-1PAR,the light response rncurve of plum as a hyperbo and the net photosynthetic rate(Pn) in leavs increased with PA elevation. Pn of rnplum tree was 20 to 22.50mg CO2 · dm-1 · h-1 at 1380μmol · m-2 · s-1 PAR,indicating that plum was typirncal C3－type fruit tree. Dial change in Pn was a bimoal curve with the highest photosynthetic rate arising rnat about 10:00 a. m. indicated the clear“none－rest”characteristic in plum leaves. Among three varieties.rnSuiLi3 had the shortest“none－rest“time followed by JiLin6 and NuXinLi. Seasonal change in Pn was a birnmodal curve with the first period of high Pn in late June and the second in late August. Pn in leaves decreased rnvisibly in period of drought in Spring and Summer.