Research On The Occurrence And Control Technology Of ’Peel Crack’ Of ’Xinli No.7’ Pear During Storage

’Xinli No.7’ is an excellent early-ripening pear variety bred with ’Korla’ pear as the female parent and ’Zaosu’ pear as the male parent.It has the characteristics of crispy fruit texture,good storage,fragrance,and red on the sun,which is loved by consumers.As the planting area and output increase year by year,its storage volume also increases year by year.’Peel crack’ is a new physiological disorder that occurred in the storage days of ’Xinli No.7’ in recent years.According to its symptom characteristics,it is temporarily named ’Peel crack’.This disorder occurred in a large range during storage and caused a serious economic loss.In view of the fact that the occurrence rule and prevention and control technology of ’Peel crack’ was not clear,the technical parameters of storage and preservation have not been reported,In this study,’Xinli No.7’ was used as the test material,and collects statistics on the incidence of disorder during different harvest periods and different temperatures during storage,and total soluble solids(TSS),fruit firmness(FF),titratable acidity(TA),vitamin C(VC),L*,h°and chlorophyll fluorescence parameters of peel and acetaldehyde content in the stored fruits were investigated at 0 and 7 days after cold storage.Respiration rate were measured during shelf days.Decay rate and stalk preservation index in different days of storage were calculated Variance analysis of related data was carried out by SPSS 22.0 software.Aiming at the symptoms and regularity of ’Peel crack’,researches on the prevention and control effect and quality maintenance of modified atmosphere packaging and 1-MCP treatment were carried out.The main results are as follows:The time of occurrence of ’Peel crack’ under different harvest periods and different temperature was after 120 days of storage.It was found that a circle of white protrusions appeared around the fruit point of ’Xinli No.7’ during storage,and then developed into a slice,which caused symptoms in a large area of the peel;When the whole fruit surface becomes extremely rough,the skin will appear black cracks.We call it ’Peel crack’.Observation of the microstructure of peel tissues of ’Peel crack’ fruit and normal fruit revealed that the cell membrane and cell wall of ’Peel crack’ gradually disappeared,and there were voids inside the peel,while the cell membrane and cell wall of the normal part were intact and the cells were closely arrangedfind.The thickness of the peel and cuticle of ’Peel crack’ fruit is greater than that of normal fruit.Harvest maturity directly affects the ’Peel crack’ occurrence,appearance and internal quality of’Xinli No.7’ fruit during storage.The study of the three harvest periods in this experiment showed that the incidence and disorder index of ’Peel crack’ in the harvest period Ⅱ during storage were significantly lower than those in other harvest periods.Stalk preservation index was the best during harvest period Ⅱ.High maturity in harvest period Ⅲ have higher incidence of ’Peel crack’.The peel brightness of harvest period Ⅲ was significantly higher than that of other harvest periods.The h°value,chlorophyll content,Fo,Fm,Fv,and Fv/Fm values of the peel were lower than those of other harvest periods.the fruit hardness in the harvest period Ⅲ is lower but the VC content is higher in the storage days.Comprehensive consideration of the incidence of fruit ’Peel crack’,fruit green keeping effect and fruit quality determines the harvest period Ⅱ as the best harvest period.Temperature directly affects the ’Peel crack’ occurrence,appearance and internal quality of ’Xinli No.7’ during storage.The results of the three temperature studies indicate thatThe results of the study showed that ’Peel crack’ did not occur at different temperatures when refrigerated for 120 days,and’Peel crack’ occurred no matter what temperature was refrigerated for 180 days.the incidence and disorder index of fruits stored at 2℃ are significantly higher than those stored at-1 ℃ and 0 0C.The fruit decay rate at 2℃ was significantly higher than those stored at-1℃ and 0℃.The color of peel,stalk preservation index,and the quality maintenance are better at-1℃ but will reduce the Vitamin C content.The later the harvest and the higher the storage temperature,the greater the occurrence of’Peel crack’,which can be inferred as a physiological disorder caused by fruit senescence.When the Fv/Fm value decreases to 0.7 and the L*value is above 75,The disorder’s risk is extremely high.The modified atmosphere packaging of ’Xinli No.7’ fruit can significantly reduce the incidence and disorder index of ’Peel crack’.It can also reduce the fruit dacy rate during storage and improved stalk preservation index.The difference between the 0.02mm PE bags and other thickness bags has a larger gap between the prevention and control of ’Peel crack’.The chlorophyll content of 0.04mm and 0.05mm PE bags was higher but the Vc content of fruit was significantly reduced.`Xinli No.7’ is a more CO2-resistant pear fruit variety.For comprehensive consideration,the 0.03mm PE bag is suitable for’Xinli No.7’ modified atmosphere packaging bag in the storage days,when maintained O2 at 15.3%-16.9%,CO2 at 1.8%-2.1%had a good preservation effect on the occurrence of ’Peel crack’.Moreover,the effect of modified atmosphere packaging on preservation ’Peel crack’ was even more evident after storage for 240 days.1-MCP treatment can significantly reduce the incidence and disorder index of’Peel crack" during storage on ’Xinli No.7’ fruits,and delay the appearance of ’Peel crack’.Different treatment methods show that 1-MCP fumigation treatment and slow-release agent treatment have better effects on the prevention and control of ’ Peel crack’,but the slow-release agent treatment has a higher dacy rate,The fumigation treatment’s comprehensive prevention and control effect is better than that of slow-release agent treatment.The effect of 1 μL·L-1 fumigation treatment is better than 0.5μL·L-1 fumigation after 240 days of storage.The effect of 1 bag of slow release agent is better than 2 bags of slow release agent.1-MCP treated fruit firmness and chlorophyll content are higher than the control.