Abstract: A plot experiment was conducted to study effects of different waterlogging durations on leaf photosynthetic parameters and actual yields of oilseed rape at the bolting stage,in which two varieties of oilseed rape,namely,Zhongshuang 9 and Huayouza 668,were used as the experimental materials. According to the results,after 7 days of waterlogging,the net photosynthetic rates （Pn） of the two varieties showed the same changing trend; After 14 days of waterlogging,the Pn of the leaves of Zhongshuang 9 went down rapidly to 9.00 μmol/（m²·s）,with the recovery ability still remaining at a certain level. While after the waterlogging for 10 days,the Pn of Huayouza 668 dropped slightly and then recovered and went up,with Tr,Gs and Ci in its leaves reflecting changing trends consistent with that of the Pn. After 17 days of waterlogging,etiolation and premature aging occurred to leaves of Zhongshuang 9,with Pn in leaves being only 1.02 μmol/（m²·s） and Ci increasing significantly,while Pn in leaves of Huayouza 668 was 18.71 μmol/（m²·s）,demonstrating a high waterlogging tolerance. With the waterlogging duration getting longer,the water use efficiency（WUE） of Zhongshuang 9 was way lower than that of Huayouza 668;; In all the waterlogging durations,the yield of Zhongshuang 9 declined much more seriously than that of Huayouza 668; At the bolting stage, Huayouza 668 had a higher waterlogging tolerance than Zhongshuang 9.

Key words: waterlogging, oilseed rape, photosynthetic parameter, yield, bolting stage