Effect Of Bagged And Protective Film Treatment On Quality Of ’Fuji’ Apple

The apple planting area of China and the production scale rank first in the world.In2021,apple planting area was 2.088 million hectares,that‘Fuji’was the main cultivar in China,nearly 70%of the total cultivated area,and bagging culture was widely used.In recent years,with the increase of labor cost,the production cost of bagging apples has been raised.The cost of annual bagging accounts for more than 30%of the total annual input cost of orchards.Bagging has become an important factor restricting the improvement of quality and efficiency and sustainable development of apple industry.Therefore,free bagging cultivation is the direction of apple industry development in China.It is of great significance to study the difference of quality between bag-free and bagging‘Fuji’apples and the effect of different protective film agents on the quality of bag-free‘Fuji’apples for the promotion and application of bag-free cultivation techniques in apple industry.Therefore,on one hand,this study systematically compared the appearance quality and internal quality of bag-free apples and bagged apples in five Fuji orchards.On the other hand,by spraying nine different types of protective film agents,effects of different film agents on the quality of‘Fuji’apple leaves and fruits were compared,advantages and disadvantages of different protective film agents were analyzed,and test results of the previous year were verified.The main results were as follows:1.Through the systematic comparison of the external quality and internal quality of’Nagafu No.2’from five apple orchards in Luochuan,it was found that the color and surface finish of bagged fruits were significantly better than those of unbagged fruits.The fruit spot size,fruit spot density and fruit rust rate of unbagged apples increased by 9.5%,23.3%and21.2%on average compared with bagged apples,and the color index decreased by 13.2%compared with bagged apples.The internal quality indexes of unbagged apples were significantly higher than those of bagged apples.Among them,the pulp hardness,pulp brittleness and pulp compactness of unbagged apples were 9.9%,7.2%and 14.2%higher than those of bagged apples,respectively.The soluble solids and solid acid ratio were 7.4%and 64.1%higher than those of bagged apples,respectively.The contents of phenolic compounds and flavonoids were 23.0%and 30.8%higher than those of bagged apples,respectively.The aroma content of unbagged apples was 2.04 times higher than that of bagged apples.However,the amino acid content of unbagged apples decreased by 18.2%on average compared with bagged apples.The contents of alanine,histidine and phenylalanine differed the most which decreased by 49.3%,47.1%and 43.7%respectively compared with bagged apples.2.In 2021,the spraying experiment of protective film agent was carried out in bag-free orchard.A total of 9 different types of protective film agents were sprayed.After principal component analysis of the measured fruit quality,7 principal components were extracted,and the cumulative contribution rate reached 78.2%.After comprehensive evaluation of fruit quality under different treatments,it was found that spraying nine protective film agents could improve fruit quality,among which two calcium film treatments had the best comprehensive effect,followed by calcium cyclamate and amino oligosaccharide treatment.Compared with the control,the chlorophyll content of leaves increased by 21.5%,the fruit point density decreased by 9.8%,the color index and soluble solids increased by 4.2%and19.9%,respectively.3.In 2022,the effects of two calcium films and one biological protective film on fruit quality were verified based on the previous year’s experiment.It was found that two calcium films were better as protective film agents to replace bagging.Compared with the control,the color index of the two calcium films increased by 6.9%and 7.0%,and the soluble solids increased by 12.0%and 7.8%,respectively.After treatment with different concentrations of amino oligosaccharides,it was found that 800 times of 5%amino oligosaccharides had the most significant effect on improving fruit quality.Compared with the control,the color index,pulp hardness,pulp crispness and soluble solids of the treatment increased by 7.3%,7.5%,3.8%and 5.1%,respectively.After spraying the mixture of prohexadione calcium and different concentrations of GA₄₊₇for 1 or 3 times,it was found that spraying 20 mg/L GA₄₊₇and prohexadione calcium once a week after flowering had a better effect on improving fruit quality.Compared with the control,the size and density of fruit spots decreased by 20.5%and 31.8%respectively,the color index increased by 5.5%,and the flesh hardness,flesh brittleness and soluble solids increased by 4.2%,5.3%and 5.3%respectively.