Research On Physiology Of Freezing Stress And Cold Resistance Evaluation Of Annual Branches Of Apple In Cold Region

Apple(Malus pumila Mill)is one of the fruits which is cultivated most widely in China.Apple grows in the cold region is popular due to its sour taste and rich flavour.But in the cold area,the low temperature is low in winter,so the cultivation of Apple often suffers from freeze injury,which causes serious losses to the production.Therefore,conducting research on the cold resistance of Apple is of great importance to the scientific research and production of it in cold areas.Taking 4 types of cold resistance resources(Jinhong,Hong taiping,Jin xiuhaitang and Shan dingzi)as experiment materials and adopting the method of manual temperature control of different gradients,this study tests one-year?old dormant branches from three aspects:the electrolyte leakage,soluble sugar of brguiches and total water content.It carries out research on the cold resistance of apples based on the comprehensive analysis.The results are as follovs:1.First of all,it studies and improves the testing method of the conductivity.In the process of low-temperature treatment of branches,the study uses programmed temperature controlling and low-temperature thermostat bath as well as temperature inspection instrument(Nanjing Atpio Instrument Manufacturing Ltd.)to monitor the change of the temperature in every minute so as to ensure the stability of the treatment temperature of branches and the accuracy of its treatment.It is appropriate to test the electrolyte leakage when the shaking time of the leach liquor is increased to 20h and the standing time after it is boiled to 2h,and the change of the electrolyte leakage by the method of vacuum supercharging is not significant.2.There are significant differences between the electrolyte leakage,soluble sugar content as well as bound water and free water of different branches or different parts of the same branch.The cold resistance of the outer part of the crown is higher than that of the inner part."Extettial branches">"Bore branch".The cold resistance of a branch is the strongest at base while significantly weak at its tip.3.Temperature is signifieantly related to soluble sugar content and bound water/free water.The change law of different physiological indexes of dormant branches can reflect their cold resistance.4.The semi-lethal temperature of the tested materials is-40.63?.Soluble sugar of branches and bound water/free water change significantly when the temperature is between-38? and-58?.The electrolyte leakage is stable when the temperature is between-48? to-58?,which shows that branches are in a state of death due to the low temperature stress.The electrolyte leakage of branches reaches 62%,which can be used as a reference for the limit value of electrolyte leakage of branches of the apple.