Effects Of Bagging On Fruit Quality Of 'Ruiyang'&'Ruixue' Apple Cultivars

‘Ruiyang' and ‘Ruixue' are two late-maturing apple cultivars newly bred at Northwest A&F University.For quicker demonstration and extension of these two new cultivars,it is quite necessary to gain an insight into their cultivating techniques.‘Ruiyang' and ‘Ruixue' with dwarf culture and standard culture were chosen as test materials in this study in Eastern Gansu Province,a comprehensive analysis was conducted on the difference in fruit quality between bagged and non-bagged ‘Ruiyang' and ‘Ruixue' apples,and pilot studies were made on the effects of bagging time and debagging time on exterior and intrinsic fruit quality.‘Ruiyang' and ‘Ruixue' were chosen as test materials,the main components of soluble sugar and their content were separated and determined by ultrasonic wave extraction(UWE)and high performance liquid chromatography(HPLC);the major volatile components of fruit and their content were extracted and determined by headspace solid-phase micro extraction(HS-PM)and gas chromatography-mass spectrometry(GC-MS),providing a theoretical basis for the bagging cultivation of the new cultivars in Eastern Gansu Province.The main research results are as follows:1.Non-bagging can significantly improve the intrinsic flavor and flavor quality of ‘Ruiyang' apple fruit provided that the exterior fruit quality is not strongly influenced.(1)non-bagging has no obvious effect on the indexes of fruit shape or fruit russeting,non-bagged ‘Ruiyang' apple fruit is obviously less susceptible to sunscald(P < 0.05);(2)Non-bagging can significantly crease single fruit weight and fruit sugar content.It contains obviously more sucrose and fructose(P < 0.05);(3)20 volatile substances are identified in non-bagged ‘Ruiyang' apple fruit,mainly including:1-hexanol,hexanal,2-hexenal,butyl butyrate,hexyl butyrate,hexyl acetate,2-methyl-1-butanol,acetic acid 2-methylbutyl ester and 2-methyl-butanoic acid hexyl ester.‘Ruiyang' is an ester-flavor apple cultivar.Bagging clears away some characteristic aroma compounds in ‘Ruiyang' apple,and reduces the total content of characteristic aroma compounds(P < 0.05).2.There is no obvious difference in influence of ‘Ruixue' apple with single-bagging and double-bagging on intrinsic quality.(1)‘Ruixue' apple with single bagging showed no significant changed total sugar content compared with double bagging fruit(P < 0.05);(2)37 major volatile components are identified in ‘Ruixue' apple fruit with non-bagging,mainly including 1-hexanol,hexanal,2-hexenal,butyl butyrate,hexyl butyrate,hexyl acetate,acetic acid 2-methylbutyl ester,2-methyl-butanoic acid hexyl ester,2-methyl-butanoic acid butyl ester and hexyls hexanoate.‘Ruixue' is an ester-flavor apple cultivar.Bagging significantly reduces the content of volatile compounds in ‘Ruixue' apple fruit,and there is roughly the same quantity of volatile compounds in both single-bagged and double-bagged ‘Ruixue' apple fruits.Specifically,there is no significant difference in ester content,while the total relative mass fraction of characteristic aroma compounds in the former is higher than that in the latter(P < 0.05).3.‘Ruiyang' should be bagged in 38~43d after flower dropping,and debagged in 164~169d after flower dropping;‘Ruixue' should be bagged in 43~8d after flower dropping,and debagged in 177~182d after flower dropping.