The Research On The Cedar Resistance To The Cold Under The Situation Of Naturally Decreasing In Temperature

This paper reviews the variable rules of SOD , CAT, MDA, Carotene, Relativity-conductance and chlorophyll in the 10-year old seedlings of cedar which have good health , under the cold stresses. The results show that: [1] With the temperature decreasing , the content of chlorophyll a has increasing trend , however, the opposite to the carotene ,but the chlorophyll b kept stable, which all show that the cedar avoided the cold stress through this self-protection. [2] With the temperature decreasing . the conductance and MDA have increasing trend ,this reviews the cold stress made the destroy of cell membrane , which lead to the foul up of metabolism. [3] With the temperature decreasing, the change of SOD and CAT both show the shape of "M" , they are one of the basic conditions relating to the cold stress of cedar.[4]During the cold stresses, the content of amylose in cedar cells has increasing trend with the temperature decreasing, which can be seen a protective reaction to the cold situation. The improvement of controlling capability on permeability can be attributed to the increase of amylose in cells, which can also decrease the freezing point, so as to improve the cedar resistance to the cold. [5] We find the effect of cold stress can be decreased , so it reviews the effect of the cold stress on cedar can be decreased after taking certain disposals . In all, the cedar avoided the effect of extreme climate after taking certain disposals which can change its microenviroment, so that it can protects itself and adapts to this extreme condition, which all contribute to the successful introducing of cedar to the north.