Studyon Cold Tolerance Mechanism Of Cinnamomum Camphora As Temperature Fell

In this paper,seven Cinnamomum camphora in shangjie district of Zhengzhou was researched as the research object . The author has investigated their related cold—resistance indexes in natural decreasing process of air temperature and also analyzed the differences of their cold-resistance among those three tree species by means of subordinate function method.The main results were described as follows:(1) All species showed some cold tolerance ability under early low temperature stress.The malondialdehyde(MDA)contents and relative electric conductivity rate (REC) of all species ascended obviously,which indicated that more lipid peroxidations occurred in the process of temperature decreasing.The soluble sugar, proline content and the activity of peroxidase(POD), superoxide dismutase(SOD), Catalase( CAT) of 3 species increased in varying degrees,which reduced the damages of low temperature stress at some degree.(2) All species were damaged badly after continuous low temperature. From January to February,2010,the leaf morphologic characteristics of all species but SJ5 changed remarkably. Some leaves morphological change occurs, leaf color fades, leaf edges become yellow. Which measured changes in chlorophyll content is consistent. In the natural cooling process, with the cooling intensity of natural cooling at different times for the test species on the leaves are caused by different degrees of membrane damage. Leaves the relative conductivity and MDA content along with the arrival of cold air again and again elevated temperatures plunged in early November, the lowest average temperature in January and 3,4 peaks appear in late spring months. The relative conductivity and MDA to some extent reflect the degree of cell membrane damage by the system.(3) In the natural cooling process, the Cinnamomum plants, while cell membrane injury, studies this experiment researched two response mechanism of Cinnamomum plants. Including: The one, adjusting the osmolyte. Soluble protein increased in the incoming cold air strikes every time. Free proline during cold protection is an important material, but the role of a bit weak, after the initial cooling gradually accumulated to maximum in mid-December, remained stable after the change.Soluble sugar content have two peaks in the natural cooling process, one in November,another in the coldest month-January. Coordination among each other to maintain cellular osmotic balance, the changes by adjusting their content to adapt to changes in temperature, thereby reducing damage to the cell membrane. The other enzymes, SOD activity of Cinnamomum plants leaves, POD activity, CAT activity in the natural cooling process is basically the same trend, through the synergistic effect to reduce the intracellular accumulation of free radicals and reactive oxygen species, defense system of its cell membrane damage Increased antioxidant capacity, thus effectively against low-temperature cold.(4)The cold tolerance abilities of six selections could be ranked as:SJ4>SJ2>SJ1>SJ6>SJ3>SJ5,using principal component analysis. Using membership function analysis,cold tolerance of six selections could be ranked as:SJ4>SJ2>SJ1>SJ6>SJ5>SJ3.SJ4 has the best performance and strongest cold tolerance. SJ4 is the best type in northern introduction.