Selection of Main Indexes for Evaluating Apple Fruit Quality

For ascertaining the main evaluation factors of apple fruit,Nine quality index were measured of fifty-eight varieties.The index included mean individual fruit weight(MIFW),fruit shape index(FSI),flesh rigidity(FR),total soluble solids content(TSS),titratable acid content(TA),pH,vitamin C content,carotenoids,the ratio of sugar acid(RSA).These data were analyzed by variation,correlation analysis principal component analysis and system cluster analysis.58 varieties of fruit quality were analyzed by variation correlation,nine index were compressed into six integrated variables using principal component analysis.Final main evaluation indicators of apple fruit were determined by using cluster analysis and correlation analysis.The results indicated that the range of variation coefficient was from 5.7% to 77.8%.Mean individual fruit weight,flesh rigidity,vitamin C,carotenoids were the important components of fruit quality,playing a major role on fruit quality.These nine index were closely related and the relatively independent.Vitamin C was significantly and negatively correlated with titratable acid content and was significantly and positively related to mean individual fruit weight.Carotenoids was significantly and negatively correlated with titratable acid content and was significantly and positively related to the ratio of sugar acid.Based on the above results,five representative index were assured for evaluating fruit quality,that is fruit weight,fruit shape index,flesh firmness,contents of total soluble solids,and content of titratable acid,which could reflect the most information of apple fruit quality.