| Apples have high economic value.Apples are widely planted and the yields are relatively large.The climate of apples in China is very different.The temperature is one of the important environmental factors that restrict the promotion of rootstock cultivation.Combined with the regional characteristics of each region,screening for cold resistance Strong apple rootstock is one of the problems to be solved in the promotion and production of apples.In this paper,Malus sieversii(ledeb.)Roem(Xinyuan County),Malus sieversii(ledeb.)Roem(Huocheng County),Malus baccata(L.)Borkh(Northeast),Malus baccata(L.)Borkh(Alar),Malus robusta Rehder(Hebei),Malus robusta Rehder(Shanxi)and Malus royalty(Alar)The annual shoots of seven varieties of real offspring are used as experimental materials.Through the study of physiological indexes of annual offspring of natural offspring under natural overwintering under low temperature stress,the logistic equation and fuzzy membership function method are used to comprehensively evaluate the population of different offspring.The size of cold resistance provides a theoretical basis for the introduction,cultivation and promotion of apple rootstock.The research results are as follows:(1)Through the study of the physiological indexes of the offspring of apple rootstock under natural overwintering,it was found that the electrolyte permeability,MDA content,SOD activity,POD activity CAT activity,soluble protein content,soluble sugar content,and proline content of the rootstock root branches showed The trend of increasing first and then decreasing;with the decrease of winter temperature,the apple rootstock solid branches are affected.The MDA content,soluble protein content and soluble sugar content in the rootstock root branches increase,and the protective enzyme activity increases.According to the differences in physiological indicators during natural overwintering,the cold resistance of the offspring of apple rootstocks was comprehensively evaluated in the order of Malus robusta Rehder(Hebei)>Malus robusta Rehder(Shanxi)>Malus sieversii(ledeb.)Roem(Xinyuan County)>Malus sieversii(ledeb.)Roem(Huocheng County)>Malus baccata(L.)Borkh(Northeast)>Malus baccata(L.)Borkh(Alar)>Malus royalty(Alar).(2)Under low temperature stress,combining with the electrolyte permeability and the regression curve fitted by logistic equation,its fitting degree is better.The low temperature half lethal temperature(LT50)fitted by logistic equation is between-21.34 ? and-24.82 ? for the branches of different rootstocks.Among them,the half lethal temperature of Malus robusta Rehder is the lowest,and that of Malus royalty is the highest,According to the half dead temperature,the cold resistance of different apple rootstocks was determined as follows:Malus robusta Rehder(Hebei)>Malus robusta Rehder(Shanxi)>Malus sieversii(ledeb.)Roem(Xinyuan County)>Malus sieversii(ledeb.)Roem(Huocheng County)>Malus baccata(L.)Borkh(Northeast)>Malus baccata(L.)Borkh(Alar)>Malus royalty(Alar).(3)With the decrease of the treatment temperature,the relative roots of apple rootstocks showed a gradually increasing membrane permeability.The electrical conductivity and MDA content of rootstocks had an overall upward trend.SOD activity,POD activity,CAT activity,solubility The sugar and soluble protein content increased first and then decreased,and the starch content decreased first and then increased with the decrease of processing temperature.During the process of continuous low temperature stress,the growth rate was different at different periods,but the physiological and biochemical indexes of applerootstocks with different cold resistance were basically the same,and the actual offspring of apple coldstock with strong cold resistance could maintain a higher temperature at low temperatures.The enzymatic activity,soluble sugar content,and soluble protein content were comprehensively evaluated according to membership function under cold stress.The cold resistance of different offspring of apple rootstocks was consistent with the LT50 fitting result.(4)In this experiment,by studying the cold resistance of the offspring of different apple rootstocks,it was found that the ranking of the results of the cold resistance of the offspring of apple rootstocks during natural overwintering and under low temperature stress was consistent with the results of fitting TL50.Based on the above results,the cold resistance is in order of Malus robusta Rehder(Hebei)>Malus robusta Rehder(Shanxi)>Malus sieversii(ledeb.)Roem(Xinyuan County)>Malus sieversii(ledeb.)Roem(Huocheng County)>Malus baccata(L.)Borkh(Northeast)>Malus baccata(L.)Borkh(Alar)>Malus royalty(Alar). |
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