中文摘要：

[目的]为白菜型冬油菜抗寒种质创新及抗寒品种选育提供依据。[方法]以抗寒性不同的白菜型冬油菜品种为材料，采用田间观察、比色法、冰晶消长法、显微测微、光合测定等技术，探讨北方寒旱区主要冬油菜品种抗寒性差异形成的形态、生理及分子机理。[结果]冬前低温阶段，弱抗寒品种多数气孔关闭或半开放，而强抗寒品种（陇油6号）气孔仍保持完全开放状态，且光合速率、根冠比、根部干物质积累均较高；可溶性蛋白与抗寒性显著正相关，而SOD、POD、CAT活性、游离脯氨酸、MDA含量与抗寒性无明显相关关系；与天油2号相比，低温下陇油7号质外体蛋白提取液形成冰晶体积小、分布均匀，形态以五边形、椭圆形和双菱形为主，具有明显重结晶抑制活性和饰品活性。[结论]冬前低温阶段，白菜型冬油菜强抗寒品种叶片气孔多数仍保持开放，Pn较高，光合产物优先分配至地下部贮存；根部抗冻蛋白表达上调，增强了其抗寒性。

英文摘要：

[ Objective ] The objective of this study was to provide an evaluation method for the development of cold tolerant Brassicacampestrisgerrnplasm. [Method] In this study, the plant morphological characteristics and physiological parameters were measured, and the molecular mechanism of cold-resistance of several cultivars was discussed. [ Result ] Under low temperature, the majority of the stomata in cold sensitive cultivars were closed or semi-closed. But the stomata in strong cold-tolerant cultivars （Longyou 6） maintained opening. The photosynthetic rate and root/shoot ratio were higher, dry matter accumulation in root of Longyou 6 was higher than those of other cultivars. Simple correlation analysis indicated that the soluble protein content was positively correlated with cold-tolerance, but no significant correlation was observed between cold-tolerance and SOD activity, POD activity, CAT activity, free proline content or MDA content. At low temperature, in comparison with cold tolerant variety Tianyou 2, the ice crystals in apoplast proteins extracting solution of ultra strong cold resistant variety Longyou 7 were slight and symmetrical. The shape of ice crystal was pentagon, elliptocytosis or bipyramidal. [Conclusion] During the pre-winter cold acclimation stage, the soluble protein content in leaves of strong cold-tolerant winter rapeseeds was high, and the majority of stomata in leaves remained opening, the photosynthetic rate was high, too. Photosynthates might be preferentially transported and stored in the roots.The expression of the antifreeze proteins （AFPs） was up-regulated in roots, which might ease the damage to cells in roots caused by restraining extracellular frozen.