| Low temperature injury is usually one of the stress factors that limit high yield and high quality of peach.In this experiment,6 peach varieties mainly planted in Shanxi Province(Jinhong mi,Jinyu mi,Dajiubao,Hongfeng huang,Ping gu14 and Qin wang)were used as test materials.The branches of 6 peach varieties in dormant stage were frozen in vitro and set at-15℃,-20℃,-25℃.The normal temperature was4℃ as control.Therelative leakeage of electrolytes and semi-lethal temperature of branches were measured under different temperature gradient.Meanwhile,the changes of physiological indexes such as MDA and proline,as well as the tissue structure of branches of various varieties were analyzed to analyze their cold resistance.The results show that:1.After 12h of cryogenic gradient treatment,germination rate was restored under the condition of25℃.The results showed that the low temperature limit tolerated by all varieties was-25℃.In-20℃,it is concluded that the germination rate of each type of ‘Jinhong mi’ 48.3%,‘Dajiu bao’ 43.5%,‘Qin wang’40.8%,‘Hongfeng huang’39.6%,‘Ping gu14’ 32.6%and’ ‘Jinyu mi’23%,by difference analysis,the best cold resistence is ‘Jin hongmi’,‘Qin wang’,‘Dajiu bao’ and ‘Jinhong mi’ has good cold resistance,‘Ping gu14’take second place,the worst is ‘Jinyu mi’.By electrical conductivity curve fitting and lethal temperature for ‘Jinhong mi’-21.97℃,‘Dajiu bao’-20.51℃,’ ‘Qin wang’-19.4℃,the‘Hongfeng huang’-17.2℃,‘Ping gu14’-15.6℃,’ ‘Jinyu mi’-13.72℃;The half-death temperature of each variety was consistent with the germination rate,indicating that the half-death temperature could be an important index for evaluating the cold resistance of Prunus persica.2.With the decrease of treatment temperature,the relative conductivity,MDA,soluble protein,soluble sugar and proline of peach branches of the six varieties showed an increasing trend on the whole.Correlation analysis was carried out among all physiological indexes,and the Membership function value analysis showed that the cold-resistance of branches was successively from high to low: Jinhong mi >Qin Wang >Dajiu bao> Ping gu14>Hongfeng huang>Jinyu mi.3.The correlation analysis between the indexes of the dormancy branches and the semi-lethal temperature of the six cultivars was carried out,and the indexes of the tissue structure that could be used as the evaluation of cold resistance were determined as Medullary ratio、 Xylem ratio、 Cortex ratio、Veneer.According to the analysis of the membership function,the cold resistance was as follows: Jinhong mi >Dajiu bao>Hongfeng huang> Qin wang> Ping gu14 >Jinyu mi.4.Based on the comprehensive analysis of the subordinate functions of the branch structure and physiological indexes of different Prunus persica varieties during the dormant period,the comprehensive evaluation of the cold resistance of each variety was obtained.The results showed that the cold resistance of each variety was as follows: Jinhong mi >Dajiu bao>Hongfeng huang> Qin wang > Ping gu14 >Jinyu mi.‘Jinhong mi’is the best cold resistance,while ‘Jinyu mi’ has the weakest cold resistance. |
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