Studies On Apple Fruit Quality Development And Correlative Factors Under The System Of Bagging Cultivation

In apple production,as one of the important measures for producing high quality and pollution-freeapple and promoting export,fruit bagging cultivation can improve fruit coloring, increase pericarp finish,reduce residual rate of pesticide,and enhance commodity value. However,it has some negative influences such as decreasing internal quality and aggravating some diseases and insect pests after bagging.During a long time of present and future, bagging cultivation is an important measure for the production of high quality and pollution-free fruit.Therefore,it is important to do further research on the physiological characteristics and cultivation techniques of fruit development under the system of bagging cultivation,and with which the proper and quantitative measures were proposed to guide fruit production,for keeping a healthy and sustainable development in the production of domestic apple industry.Under the microenvironments of bagging cultivation,the change of microorganism population structure,development process of pericarp and glucose metabolism of fruit as well as the response of fruit internal quality to different cultivation measures, including bag types,dates of bagging and removing,exogenous plant growth regulators and glucose,leaf spraying fertilizer,pruning methods and coloring-promoted measures were studied by using Red 'Fuji' apple as material.The results were in followings:1.Under the microenvironments of fruit bagging,Alternaria had always been the major fungi in different bags,sites of fruit and weather conditions during the whole growing season. As the secondary major fungi,Penicillium had always been after July and emerged later in inner bag and cortical pore than other sites.In the bag with which the inner bag was red and waxing,Trichoderma was isolated first in pericarp without cortical pore and inner bag as well as later in cortical pore after August.In 'Kobayashi' bag which inner bag was red and waxing, Aspergillus and Fusarium were isolated in pericarp without cortical pore and cortical pore after bag removed.Alternaria and Penicillium were isolated in unbagging fruit and 'Qianwei' bag which inner bag was red and unwaxing and the date Penicillium was isolated in CK was 45d later than bagging treatment.Under high temperature weather condition,there were no differences in the fungi population structure on fruit surface among all treatments.And the fungi population structure on fruit surface in bagging apple was more than that of unbagging ones under overcast and rainy condition.The major actinomycetes under bagging cultivation were Cinereus and Albosporus,Viridis as well as Flavus were also isolated after bagging.2.It had basically identical tendency for cuticle film,size and array of epidermal cell of fruit pericarp with different types of bag.During the prophase and anaphase of fruit growth, light,deep and very few V-type concaves generated in 'Kobayashi' bag,'Qianwei' bag and unbagging fruit,respectively.At the same time,1～2 layers mechanical tissue of bagging fruit was thinner than unbagging fruit with 2～3 layers.3.For bagging treatments,the content of sucrose,fructose and glucose in fruits were decreased,while the sorbitol content was increased.The activity of sorbitol dehydrogenase (SDH),neutral invertase(NI) and acid invertase(AI) were lower than that of control,while the activity of sucrose phosphate synthase(SPS),sucrose synthase(SS) and sorbitol oxidase (SOX) were higher than that of control.There were positive correlation between sucrose content,sorbitol content and fructose content,glucose content.Relativity of sucrose content and glucose content was increased,while that of sucrose content and fructose content was decreased after bagging.Relativity of sorbitol content and glucose content was decreased, while that of sorbitol content and fructose content was increased after bagging.4.The influence of different kinds of bags on fruit indexes assumed a basically identical tendency.Application effect of the bags accorded with the standard of 'apple fruit bags' regulations were superior to those inconsistent with the standard,as a whole.5.The earlier bagging,the higher finish index and the soluble solidscontents.Fruit hardness was increased and the incidence of bitter pit disease was reduced by later bagging. Fruit coloring was inhibited by both earlier and later boagging,and there was no significantly effect on fruit weight by bagging time.The earlier debagging,the higher coloring index and the soluble solids contents as well as the later debagging,the high fruit finish.There was no obvious relation in fruit hardness,weight and the incidence of bitter pit with different debagging time.Comprehensive survey on the main indexes of fruit quality,it is suitable to bagging 40d after blooming,to debagging 14d before harvest for Red 'Fuji' apple.6.For the treatment with GA₃,100 mg·L^-1 of which for fruit surface and fruit stalk and 60 mg·L^-1 for bourse shoot after debagging were beneficial to increase the sugar contents. Fruit surface treated by 100 mg·L^-1 IAA and fruit stalk treated by 20 mg·L^-1 IAA after debagging,bourse shoot treated by 100mg·L^-1 IAA when the beak of seed becoming brown had a remarkable effects on improving the sugar contents.Fruit surface treated by 20 mg·L^-1 6-BA before bagging and bourse shoot treated by 100 mg·L^-1 6-BA when the beak of seed becoming brown were beneficial to improve the sugar contents.7.Exogenous spraying sugar could improve the internal quality of fruits.For sorbitol,the concentration of 2%was better,while the concentration of 5%sucrose,fructose and glucose was better.8.Branch bending,shoot wresting and pinching could increase the contents of soluble solids,soluble sugars,the ratio of sugar and acids,while decrease the content of starch and organic acid.The effect of pinching twice treatments was better than that of one time.9.0.4%～0.5%of KH₂PO₄,0.4%of Ca(NO₃)₂ and trace fertilizer of 800 times for foliage spraying affected fruits internal quality significantly.10.For Red 'Fuji' apple,different color promotion measures promoted fruit coloring, decreased the flesh firmness and soluble solids content also in varying degrees.The treatment of 'leaf picking+fruit rotating+reflecting film paving' was obviously better than that of 'leaf picking+fruit rotating','reflecting film paving','leaf picking' and ' fruit rotating'.