Study On Selection Of Suitable Paper Bag, Fruit Quality And Its Metabolism-Related Enzyms In Pear Fruits After Bagging

Bagging cultivation was one of the most useful techniques for the Production of pear fruits with high quality. The technique was applied widely in Pear Production. The experiment was carried on'Cuiguan','Yali','Niitaka','Mantianhong' and 'Korla Fragrant' pears which 15 and 12 kind of fruit bags was used from 2008 to 2010. Meanwhile, the changes of carbohydrate content and the metabolism-related enzymes activity of 'Cuiguan' and'Whangkeumbae'pear fruits were measured after bagging.The aim was to research the inherent physiology mechanism that the fruit bag lowered the inside qualities of fruit, which hoped perfecting the bagging technology and guiding the pear production. The results indicated as follows:1,Bagging could change the microenvironment and got remarkably improved in appearance and internal qualities. There was a negative correlation between the changes of temperature and humidity in the bags, showing a very significant negative correlation, and chlorophyll content of pear peel in the bagged fruits were lower than those of the control, and clearly decreased the content of chlorophyll. The results showed that two kinds of enzymes, the PPO and POD, which are relevant to the metabolism of phenolcompounds, the activities were lower than those of the control, and fruit bagging could obviously improve fruit skin color, reduce russet, dot density and dot diameter of pears.2,The results showed that the sugar content and enzymes activities under bagged conditions had almost the same changes as those of unbagged conditions of two cultivars 'Cuiguan' and'Whangkeumbae' during development. The sugar content in the bagged fruits were lower than those in the control fruits.At an early stage of fruit development, sugars accumulated slowly due to higher enzyme activity for sucrose cleavage than for sucrose synthesis. At a fruit ripening stage, the sugar content increased rapidly because the enzyme activity for sucrose synthesis was higher than for sucrose cleavage. The activities of invertase at the early stage, sucrose phosphate synthase and sucrose synthase at the late stage influenced by bagging may be responsible for the decrease of sugar content in the bagging fruits.3,Fruit bagging could obviously improve fruit skin color, reduce russet, dot density and dot diameter of pears. The fruit firmness in bagged fruit were higher than CK, and TSS (total soluble solid), total soluble sugars, Vitamin C, titratable acidity and fruit weight on average were decreased. The quality of the fruit bagged with outer yellow stencil and inner yellow double-layer bag(Treatment B-2) for'Cuiguan','Yali'and outer yellow striae and inner black double-layer bag(Treatment B-5) for 'Niitaka' among the 15 types of bag were the best. Red inner and black-inner yellow-outer outer double-layer bag(Treatment B-9) for 'Mantianhong' and 'Korla Fragrant' pears among the 12 types of bag were the best.