Abstract: Changes of photosynthetic characteristics of cucumber leaves during unfolding in solar-greenhouse were studied. The results showed that the unfolding rate of cucumber leaves at different stages was different obviously. The leaves unfolded at quicker speed in Oct.-Nov., and the leaf area was the largest on 35 d after leaf came out. While those of Dec. 1 leaves on 45 d, and their largest leaf area were less than those of Oct. 14 leaves. The unfolding rate and the largest leaf area of the leaves which came out on Feb. 1 were among those of leaves came out on Oct.14 and Dec. 1. The pigment content of leaves at different stages increased at prophase, then decreased gradually. The photosynthetic rate increased as leaves unfolding, and reached maximum on about 20th day. The light saturation point and compensation point of leaves came out in each peroid mostly decreased as they spread. AQY changed as single-peak curves, and the peaks appeared on 20-40 d after leaves came out. CE reached maximum on 20-30 d after leaves came out, and the leaves came out on Oct. 14 ascended and descended with the quickest speed, whereas those on Dec. 1 changed with the slowest speed. The Fv/Fm and фPSⅡ increased as leaf area increased, and 40-50 days later, they decreased slowly. During leaves coming out, stomatal and non-stomatal factors existed simultaneously, and they all affected Pn. While the decline of photosynthetic function mainly depended on the non-stomatal limitation in the course of senescene.

Key words: Cucumber (Cucumis sativus L.), Photosynthetic characteristic, Photosynthetic efficiency, Photochemical efficiency