Study On Cold Resistance Of Amygdalus Pedunculata Pall.

Amygdalus pedunculata Pall.is a species of almond which is considered as a rare and sand-fixtation in the northwest China with high visual and medicine value. However, the studies on the cold resistance of Amygdalus pedunculata Pall. were not carried out. In order to strengthen the protection and utilization of the Amygdalus pedunculata Pall. resources, this paper carries on the study about the cold resistance of Amygdalus pedunculata Pall..This experiments used below methods and involved below content: With one-year-old branches of sand A.pedunculata Pall. and introduced cultivated almond variety"Xian feng"by different low temperature treatments used as the experimental materials, the relative leakage of electrolytes, the contents of Proline, Malondialdehyde(MDA) content, the contents of soluble sugar, the contents of soluble protein, the rate of Superoxide anion and protective enzyme activity were measured and compared. Through analysis of indexes of these physiology and bio-chemistry, it clears that Amygdalus pedunculata Pall can resists lower temperature, according to the result, we can evaluate the cold resistance of Amygdalus pedunculata Pall., make a preliminary study on screening and identification of evaluating system of cold resistance of Amygdalus pedunculata Pall. at the same time, comprehensive evaluation on germplasm resources of Amygdalus pedunculata Pall.The results show:(1) The relative conductivity under low temperature treatment was fitted by Logistic equation and calculated the temperature of inflexion points, By this way it can obtain that the semilethal low temperature(LT50) of Amygdalus pedunculata Pall and control cultivars"XianFeng"were respectively -31.05℃and -21.03℃, the cold resistance of Amygdalus pedunculata Pall. was stronger than control cultivars"XianFeng".(2) With the low temperature stress aggravated, the content of the soluble sugar of branches with Amygdalus pedunculata Pall. increased gradually, under the mild stress, its amount increased was less, only under moderate stress, its amount increased was more, but under severe stress, the content of soluble sugar began to decrease, and content of soluble sugar of weaker control cultivars of cold resistance decreased more early than Amygdalus pedunculata Pall..(3) With the low temperature stress aggravated, the content of free proline of branches with Amygdalus pedunculata Pall. increased gradually, under mild and moderate low temperature stress, the content of free proline significantly increased to 370%; under severe stress, the content continued to increase continuously, but amplitude increased was more gentle.(4) Under mild low temperature stress, the content of MDA of branches with Amygdalus pedunculata Pall. was not increased significantly; but under the moderate stress, the content was increased significantly. The result show that adaptation of Amygdalus pedunculata Pall. was more stronger under moderate low temperature stress. With the SOD activity decreasely significantly, the content of MDA increased, the result indicated that content of free radicals was increased under low temperature stress, and it inhibitted SOD activity.(5) Under low temperature stress, SOD and POD activity of branches of Amygdalus pedunculata Pall. trended to increase on the whole, but its activity did not stablely increase, they first incased and then reduced, especially in POD. Under mild low temperature stress, protective system of enzymes of cell played a important role in resisting the low temperature, but excessive low temperature damaged the structure of cell, and led to the drop of SOD and POD activity.(6) From the experimental result, we can understand that these indexes of relative conductivity, the content of soluble sugar and free proline and MDA, enzymes activity and formation rate of superoxide anion can be applied to the study on cold resistance of Amygdalus pedunculata Pall., the relative conductivity was espscial more important.(7) Because the cold resistance of Amygdalus pedunculata Pall. is more stronger than introduced cultivated almond variety"Xian Feng", A.pedunculata Pall. can live through winter in the areas that variety"Xian feng"is cultivated and in some areas of North Shaanxi. Temperature is possible not the only reason that engenders its natural death in sandy land. Being endangerment plant of living in desert, the cold resistance of Amygdalus pedunculata Pall. is more stronger, and it can be as a rootstock of cold resistance and be applied and extended.