Abstract: To explore the reasons for difference in mechanism of cold resistance of winter rapeseed of Brassica rape and Brassica napus.The method of combining field and pot culture was adopted,and using 8 different cold resistance of winter rapeseed varieties as materials,before wintering period with 5 to 6 true leaves,field experiments researched botanical morphology and accumulation of dry matter,the physiological characteristics were measured by pot experiment after the treatment of 24℃→10℃→5℃→0℃→-5℃→-10℃ 48 h.The results showed that winter Brassica rape was creeping growth,growth point was under the ground,accumulation of dry matter was mainly concentrated in the underground part,such as fresh matter of underground parts and dry matter of underground parts of winter Brassica rape had increased,which average increased 236.1%,263.0% than winter Brassica napus respectively.It was showed that the photosynthetic organic product of strong cold resistant varieties was preferentially allocated to the underground part during the vegetative growth stage,to establish a large root system to provide metabolic energy for the safe winter.With the change of temperature,the physiological and biochemical indexes of different varieties was vary greatly,SOD activity of Longyou 7 increased 10.7% than CK at low temperature of -5℃,CAT and POD activity of Longyou 7 increased 24.7%,28.6% than CK respectively at 0℃,SP content of winter Brassica rape average increased 32.3% than winter Brassica napus at 0℃,SS content of winter Brassica rape average increased 71.4% than winter Brassica napus,and MDA content of winter Brassica napus average increased 52.8% than winter Brassica rape at low temperature of -10℃,this indicated that the strong cold resistant varieties could protect themselves from damage of low temperature condition,the CAT,POD,SP were protective substance of against chilling injury,but SOD,SS were protective substance of against freezing.Therefore,the winter Brassica rape had obvious advantages in the morphology and physiological level than winter Brassica napus,the morphological advantages was that to withstand cold weather of extreme,to provide metabolic energy of during the wintering period and regreen next year;At physiological levels,the activities of protective enzyme and content of osmotic regulation of winter Brassica rape increased significantly at low temperature stress to protect the structure of cell membrane,and the accumulation of MDA was decreased,to alleviate hurt of winter rapeseed leaves at low temperature,so the over wintering was ensured highly,it was important to provide a theoretical basis for the research on the cold resistance of winter rapeseed of Brassica rape and Brassica napus in the North of China.

Key words: Brassica rape, Brassica napus, Winter rapeseed, Cold resistance, Morphological characteristic, Dry matter accumulation, Physiological and biochemical, Membership function

CLC Number: 

• S565.01