Research on Improving Cold Resistance of Different Ages of Korla Fragrant Pear by CaCl_2 Treatment

【Objective】This project aims to conduct study on the relationship between CaCl2 of different concentrations and different ages to improve the cold resistance of Korla Fragrant Pears. 【Method】5a,15a and 25a of Korla Fragrant Pear trees were taken as the test materials,and during the leaf expansion period( from May 5,2012),10 mmol/L,15 mmol/L,20 mmol/L,25 mmol/L concentrations of CaCl2were sprayed every other 20 days,altogether three times. During the period of dormancy,branches were sampled and membrane permeability and proline content in the artificial cryogenic stress were determined.【Result】As the stress low temperature decreased,the membrane permeability,proline content of different Pear 1a branches increased to varying degrees. Spraying CaCl2could improve the cold resistance of Korla Fragrant Pear. 5a and 25a Korla Fragrant Pear trees after 20 mmol / L CaCl2treatment,15a Korla Fragrant Pear trees' membraneprotective ability could be improved by 10 mmol / L CaCl2treatment effectively,then the content of proline, and the cell osmotic adjustment ability were improved,as well. The accumulated amount of proline content of the 5a Korla Fragrant Pear trees reached the maximum degree,78. 78% higher than the 15a the Fragrant Pear tree proline accumulation. The increased rate was 5. 86 times,and the membrane permeability increased by 3. 85 times. Membrane permeability of 15a Fragrant Pear trees was increased by 3. 11 times,and the proline content increased by 79. 05%. Membrane permeability of 25a Fragrant Pear trees increased by 2. 58 times, and the proline content increased by 88. 64%.【Conclusion】Spraying CaCl2can improve the cold resistance of Korla Fragrant Pear trees. But the research was carried out in different growth periods of foliar spraying,and in artificial cryogenic stress,the cold resistance determination of branches was away from the parent,so in the future,different testing methods of improving cold resistance need further research.