Abstract: The ultrastructure and photosynthetic characters of chloroplast were investigated at setting stage in leaves of glabrous and normal cucumbers. Compared with that of normal cucumber , the structure of photosynthetic
apparatus in glabrous cucumber was simple with less numbers of chloroplast and grana as well as the grana lamellae. The contents of chlorophyll a and b and carotenoid in glabrous cucumbers only reached half of the content in normal one. Therefore , the capacity of capturing light energy was low. The photosynthetic rate of glabrous was obviously lower than that of normal , no more than half of normal cucumber during most times in a day. Diurnal change of photosynthetic rate of glabrous was unimodal distribution with the maximum occurring at 11 :00 , whereas diurnal patterns of normal one displayed bimodal distribution which two peaks occurred at 10 :00 and 12 :00 . The photosynthetic rate of glabrous cucumber increased as CO₂ concentration increased , the maximum reached 1300μL·L ^{- 1} of CO₂ , but its level was significantly lower than that of normal cucumber under the same CO₂ concentration.

Key words: Cucumber, Glabrous foliage, Ultrastructure of chloroplast, Photosynthetic character