Studies On Physiological Change Of Machilus Ichangensis Under Chilling Stress

The test for Machilus ichangensis Lauraceae samples were studied under low temperature stress seedlings Machilus ichangensis chlorophyll, malondialdehyde, free proline, soluble protein, soluble sugar content changes; changes in cell membrane permeability; SOD, POD, CAT activity changes and changes in chloroplast ultrastructure. The results showed that:1.The change of chlorophyll content: Machilus ichangensis chlorophyll a, chlorophyll b, total chlorophyll basically the same trend, that is, the lower the temperature, the content is gradually reduced, and chlorophyll a / b is reduced as the temperature slowly rising trend, in which a decrease of chlorophyll b than chlorophyll a big drop.2.Membrane permeability and MDA content changes: With the stress of the lower temperature Machilus ichangensis leaves and roots increased membrane permeability, MDA content increased, caused by low temperature stress proof membrane lipid peroxidation.3. Osmolyte content changes: the process at low temperatures, leaf soluble protein content and soluble sugar content as the temperature has reduced the overall upward trend, while the soluble sugar content in roots decreased, and the whole process of temperature stress , the leaf protein content and soluble sugar content in the root system is always higher than that of cold resistance than the root leaves. Changes in proline, the roots and leaves of the same trend, generally show a downward trend.4.The protection of the changes in activity: in the entire process of low temperature stress Machilus ichangensis leaves and roots activity of CAT and SOD activity similar trend, showed a single peak curve, which showed an increase -- - the decline in the law; POD activity showed an upward trend, but the smaller the increase.5. Chloroplast ultrastructure: In this experiment, Machilus ichangesis with lower temperature and a gradual increase in the number of mitochondria and the ability to accumulate starch, which may imply that the resistance of its potential capacity. However, in -5℃, the reduction of starch grains, cell structure fuzzy on Machilus ichangensis symptoms have been apparent injury.6. Though correlation analysis about physiological indexes, the results showed that: Machilus ichangensis leaves and roots of the membrane permeability and MDA content, SOD, POD, CAT showed a positive correlation; soluble sugar content with the three types of activity were negatively correlated .7. The results of this study showed: one-year-old Machilus ichangensis the cold resistance of seedling roots system below the leaves, the roots has reached the semi-lethal temperature under -5℃the conditions and the leaves have been significant injury symptoms.Machilus ichangensis seeding can't survive the low temperature of -5℃,needs protective measures to survives the winter.