中文摘要：

以白菜型冬油菜不同抗寒品种（系）为材料，分别在原种植区（甘肃天水）及北移区（甘肃临洮、兰州和永登）设置田间试验，采用田间记载、光合参数测定和显微观察相结合的方法，调查参试品种（系）在4个生态区的苗期形态、光合参数及气孔形态。结果表明，与原种植区（天水）相比，冬油菜北移后苗期生长习性由半直立逐渐变为匍匐生长；冬前低温阶段叶片Gs、Ci明显下降，正明显上升，弱抗寒的天油品种冬前低温下叶片气孔处于关闭或半关闭状态、Pn下降，而强抗寒的陇油品种叶片气孔仍完全开放、Pn明显升高；北移区冬油菜日出叶数减少，根长、根直径增加。冬油菜北移后，苗期匍匐生长，强抗寒品种叶片光合作用增强，弱抗寒品种减弱，有机物被优先分配到根部。

英文摘要：

We conducted field experiments in Tianshui （original planting area）, Lintao, Lanzhou, and Yongdeng （extending north- ern areas）, Gansu province, to investigate the seedling morphology, photosynthetic parameters, and stomatal morphological char- acteristics ofBrassica campestris varieties （lines）. The results showed that growth habit of winter rapeseed seedlings was changed from suboptimal-erection into prostrate in the northern regions as compared with that grew in the original region. Gs and Ci of leaf were decreased, while Tr was increased in low temperature treatment. When moved to the northern-extended regions, Pn of the cold sensitive varieties （lines） was decreased, while Pn of strong cold resistant varieties （lines） was increased. The number of daily emergency of leaf in northern-extended winter rapeseeds was reduced. The root length and root diameter were increased. Stomata of strong cold resistant varieties （lines） maintained open, while the majority of stomata of weak cold tolerant varieties （lines） were closed or semi-closed. When moved to northern-extended regions, seedlings of winter rapeseed were prostrate; the photosynthesis of strong cold resistant cultivars was enhanced, while those of weak cold tolerant varieties （lines） was reduced. The photosyn- thates products were preferentially transported into the underground parts and stored in roots.