| Although the bagging production improved the appearance quality of the apple fruit,the internal quality of the fruit decreased.In addition,the production cost is large and the waste of resources was serious,which restricts the development of the apple industry.Therefore,the study of the effect of bagging cultivation on the internal and external quality of apples,so that apples not bagging can achieve the coloring standard of bagging,can promote the transformation and development of China's apple industry to a large extent.In this experiment,four apple varieties,? Nagafu No.2?,? Yanchanghong?,spur-type ?Longfu ? and ?Honeycrisp?,were used as experimental materials.Three treatments were carried out unbagging,spraying biofilm and bagging.Effects of different treatments on single fruit weight,yield per plant,soluble solid content,storability,fruit coloration,peel structure,fruit rust index and other indexes were analyzed,to clarify the effects of no unbagged cultivation on the quality of apple fruit,which provides some theoretical basis for the bagless cultivation of apple.Fruit russet affects the cleanliness of apple fruit,which reduces the appearance quality of apples.Therefore,it is particularly important to explore the main factors that cause apple fruit russet.In this experiment,the rust occurrence of the fruit surface irritation treatment of ?Nagafu No.2? was analyzed,the structure of the peel observed by scanning electron microscopy,exploring the sensitive period of fruit rust and providing a basis for the prevention of apple fruit russet.The test concluded the following main results:1.Spraying biofilm significantly improved the leaf area,chlorophyll content and photosynthetic rate of ?Yanchanghong?,spur-type ?Longfu?,?Nagafu No.2? and ?Honeycrisp?,indicating that spraying biofilm could significantly promote the development of leaves,apple tree body and fruit.2.Bagging made the apples bright red and the fruit surface was smooth.Spraying biofilm could significantly promote the coloration of apples,make apples brighter,and significantly reduce the fruit rust index and the sun burning rate of ?Yanchanghong?and purtype ?Longfu?,?Nagafu No.2? and ?Honeycrisp?.?Yanchanghong? and pur-type ?Longfu? were brightly and evenly colored without bagging,which could be used as research basis for non-bagging cultivation.3.Soluble solids and single fruit weight in bagged fruits were lower than those unbagged.Fruit soluble solids content of ?Yanchanghong?,?Nagafu No.2?,pur-type ?Longfu? and ?Honeycrisp? was significantly increased by 19.29%,18.95%,24.41% and 13.67%,and the hardness was significantly increased by 8.35%,5.08%,3.70% and 11.60%;the single fruit weight was significantly increased by 13.45%,15.53%,21.88% and 14.64%,after spraying biofilm.These results showed the non-bagging cultivation significantly improves the intrinsic quality of the fruit and the fruit had good flavor.Spraying biofilm significantly improved the single fruit weight,soluble solid content and solid acid ratio.Spraying biofilm improved the intrinsic quality of apple fruit and improved fruit flavor.4.Non-bagging could improve the storability of apples.During the storage period,the weight loss rate of the three treatments showed an upward trend.The weight loss rate of the bagged fruit was always higher than unbagged fruit;the hardness showed a downward trend,and the hardness of the fruit unbagged was always higher than those bagged,which indicated that the storability of the fruit unbagged cultivation 0~150 d was higher than that in the bagging treatment;And ?Honeycrisp? still maintains a good hardness at the end of the storage period,which is a good variety of ?Honeycrisp?.The soluble solid content showed an upward trend,and the soluble solid content of the fruit unbagged was higher than that of bagged within 0~120 d.5.In this test,no organic phosphorus and pyrethroid pesticides were detected in unbagged fruit and bagged fruits;the young urea was not detected in the bagged fruit,while was detected in the fruit of bagging and spraying biofilm.The content was 0.011 mg/kg and 0.020 mg/kg,respectively,but they did not exceed the maximum limit of mung-killing pesticide residue in China(MRL 3.0 mg/kg);carbendazim and imidacloprid were detected in all three treatments.However,they did not exceed the maximum amount of carbendazim and imidacloprid pesticide residues in China,which showed that bagging reduced the pesticide residues in the fruit,and the fruit sprayed with the biofilm achieved the safety standard.6.The total cost of bagging was 2,500 yuan,of which the cost of fruit bag was 1,000 yuan and the labor cost was 1,500 yuan.The total cost of bagging was 1880 yuan higher than the cost of spraying biofilm,and was 2,500 yuan higher than that of non-bagging.7.No visible fruit rust appeared on the fruit of ?Nagafu No.2? spraying biofilm and baggged in falling flowers 6 weeks and 7 weeks after.The Scanning electron microscope(SEM)results showed that the epidermal cells of the pericarp were neatly arranged,while the fruit rust of ?Nagafu No.2? fruit unbagged(control)in 5 weeks to 7 weeks after flowering,was severe to a certain extent,and the structure of the peel was characterized by waxy layer upwarping and shedding;the stratum corneum was detached and the crack was deepened;only a small amount of residual were left in the stratum corneum and large cracks appeared in the epidermal cells,which explain that spraying biofilm and bagging reduced the occurrence of ?Nagafu No.2? fruit rust.8.?Nagafu No.2? fruit rust occurred in the young fruit period.The peel structure of fruit varied with the occurrence time of fruit rust.During the initial stage of fruit rust,only a small amount of waxy layer were shed off on the epidermal cells,and the epidermal cells were arranged neatly,but with the severity of fruit rust deepening,the waxy layer of the epidermal cells and the stratum corneum fell off,and large cracks appeared in the epidermal cells. |
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