Study On Biological Charateristic Of Desert Plant Prunus Mongolica Maxim.

Prunus mongolica Maxim. is a special deciduous shrub , one of the landscape and water and soil conservation plants ,one of the antiquity relic plants, and one of the medicinal and ligneous oil plant, in the desert area and desert steppe of Mongolia Plateau . It belongs to the national tertiary conservation endangered plant ,which has a high value of research and exploitation.In this paper,the author analyses seed component of Prunus mongolica Maxim from exploitation and utilization , the varietions of biochemical characteristics in seed germination of Prunus mongolica Maxim and the water physiological characteristics and the varietion of these characteristics on drought stress in seedlings and mature plant of Prunus mongolica Maxim from conservation . The results indicate that the content of raw protein is 26.77% in seed of Prunus mongolica Maxim, the categories of its protein amino acids are various, including 18 kinds of amino acid , the ratio of essential amino acid and nonessential amino acid is appropriate, the close degree is 0.865 and the protein nutrition is superior to soybean .There is ample fat in seed of Prunus mongolica Maxim, the content is 51% ,the categories of fatty acid is simple ,including just four fatty acids: Oleic, Linolic, Palmitic and Stearic ,and Oleic and Linolic occupyes 97% in fatty acid . The experiment has proved that seed vigor of Prunus mongolica Maxim decreases on drought stress ,which is believed to be one of the reasons for making the Prunus mongolica Maxim an endangered plant .In seed germination of Prunus mongolica Maxim, drought stress has inhibiting function to the activity of hydrolyzation enzyme ,which results in the hydrolyzation of fat restrained and the course of increasing of free fatty acid postponed. Because the soluble sugar is primarily converted by fatty acids in seed germination of Prunus mongolica Maxim , the content of soluble content is lower in the beginning and increases gradually later ,but the increment is lower than compared groups . The analyses of heteroauxing ( indole acetic acid )oxidation enzyme in roots of seedlings of Prunus mongolica Maxim make it clear that with 5%PEG and 8%PEG imitating drought stress to deal with the seedlings ,the activity of heteroauxing oxidation enzyme is 2.72 and 7.00 times lower than the compared groups .Under the usual water condition ,the seedlings of Prunus mongolica Maxim have lower water content (68.7%),lower water potential of leave(-0.85MPa),higher bound water content (39.9%), higher ratio of bound water to free water and higher critical saturation deficiency(48.11%).but on the drought stress ,the relative water content ,water potential of seedlings of Prunus mongolica Maxim, drops29.51% and14.12%,ratio of bound water to free water increases4.72 times ,critical saturation deficiency increased 32.22% ,intensity of transpiration lowers10 times .It is obvious that the seedlings of Prunus mongolica Maxim have the capability to make osmotic adjustment on the drought stress, and the mostly osmotica is proline and soluble sugar ,but it is not apparent of the accumulation of K+,Na+. The seedlings of Prunus mongolica Maxim have strong capability of dehydration and after 3 days′drought stress of 3% PEG ,the speed of dehydration drops in seedlings of Prunus mongolica Maxim, the hour of reaching lasting weight prolongs from102h to 152h in compared groups. The analyses of PV curve of branch in the that year indicates that the water potential of leaves of Prunus mongolica Maxim is -2.49MPa ,the critical osmotic potential is 3.11MPa , the ratio of bound water to free water is 3.83 , Bulk modulus of elasticity εmax is 4.18MPa . It can be inferred from those characteristics of water physiology that the seedlings of Prunus mongolica Maxim have a strong adaptability to drought stress . The activity of superoxide dismutase ( SOD) and peroxidase(POD) of seedlings of Prunus mongolica Maxim increases1.88 and 2.46 times on drought stress , but the activity of catalase decreases by 11.25% , the content of cell membrane lipid oxidation substance of malonic dialderhyde(MDA) increased by 21.13% .And the results have shown that the ability to eliminate free radical of the seedlings of Prunusmongolica Maxim is strengthened and at the same time cell membrane lipid oxidation and membrane damage strain have occurred in different .All of which have also explained that drought stress is one of the environmental factors in making the Prunus mongolica Maxim became an endangered plant.