Analysis and evaluation of fruit quality of Ehime 28 and Harumi in Meishan City, Sichuan province

Abstract: 【Objective】The study aimed to understand and master the fruit quality of the main citrus varieties in Meishan City, and comprehensively evaluate the fruit quality of each variety in various districts and counties to provide theoretical basis for the adjustment and promotion of citrus variety structure in Meishan City.【Methods】Using Ehime 28 (Citrus reticulate) and Harumi [C. reticulate × (C. reticulata× C. sinenesis)] orchards collected from 4 or 5 districts and counties in Meishan City as materials, 15 kinds of fruit quality indicators were measured, and principal component analysis was used to comprehensively evaluate the same variety from different districts and counties, and the score ranking was calculated.【Results】The single fruit weight of Ehime 28 varied from 149.8 g to 353.13 g, with an average of 245.24 g. The soluble solids content (TSS) range was 7.6% to 13.4%, with an average of 10.79%; The titratable acid content (TA) ranged from 0.49% to 0.94%, with an average of 0.70%; The vitamin C content (Vc) ranged from 26.4 mg·100 mL^-1 to 50.47 mg·100 mL^-1 , with a mean of 36.82 mg·100 mL-1 ; The variation range of TSS/TA was 10.42-21.25, with an average of 15.66. The single fruit weight of Harumi varied from 162.38g to 392.74 g, with an average of 242.84 g. The distribution range of TSS was 9.7% to 13.7%, with an average of 10.97%; The distribution range of TA was 0.4% to 1.2%, withan average of 0.81; The distribution range of Vc was 24.95 mg·100 mL^-1 to 42.71 mg·100 mL^-1 , with a mean of 35.37 mg·100 mL^-1 ; The distribution range of solid acid ratio was 8.82-27.99, with an average of 14.43. Discriminant analysis showed that the comprehensive quality of Ehime 28 and Harumi fruits collected from different districts and counties had varying degrees of separation, and the comprehensive quality of the citrus fruits collected from the same district and county tended to cluster together, indicating that there are certain differences in the comprehensive quality of the citrus fruits collected from different districts and counties. 11 fruit quality indicators of Ehime 28 were selected and the principal component extraction was performed. Four principal components were extracted based on the principle of eigenvalues over 1, with a cumulative variance contribution rate of 75.646%. The single fruit weight and juice yield loadings were higher on PC1, the longitudinal diameter loadings were higher on PC2, the CCI loadings were higher on PC3, and the edibility loadings were higher on PC4. Similarly, after converting the data of the 11 fruit quality indicators of Harumi, the principal component extraction was performed. A total of 4 principal components were extracted based on the principle of eigenvalues over 1, with a cumulative variance contribution rate of 76.940%. On PC1, the load on longitudinal diameter, skin thickness, and juice yield were higher, on PC2, the load on peel hardness were higher, on PC3, the load on TA was higher, and on PC4, the load on CCI was higher. The average comprehensive scores of fruit quality of Ehime 28 were arranged in the order of Dongpo District＞Renshou County＞Danling County＞ Pengshan District. The average comprehensive score of Dongpo District was significantly higher than that of Pengshan District, but there was no significant difference between Renshou County and Danling County. The average comprehensive scores of Harumi fruit quality was arranged in the order of Pengshan District＞Dongpo District＞Danling County＞Renshou County＞Qingshen County. The average comprehensive score of Pengshan District was significantly higher than Renshou, Danling, and Qingshen County, and there was no significant difference from Dongpo District. For the convenience of rapid detection and grading of the fruit quality in the future, the evaluation factors for the quality of Ehime 28 and Harumi fruits in Meishan City were simplified, and the most representative indicators were selected. The cluster analysis was performed on various quality indicators, and the indicators clustered into one category showed high similarity. Combined with the PCA load matrix, the highest load indicator was selected to replace this type of quality indicator. The indicators grouped separately into one category were relatively independent. Finally, the single fruit weight, lateral diameter, juice yield, TSS and Vc were chosen for Ehime 28; the CCI, longitudinal diameter, skin thickness, juice yield, and Vc were selected for Harumi as core indicators.【Conclusion】This study clarifies the quality performance of the main citrus varieties planted in Meishan City and the differences between different counties, which has certain reference significance for optimizing and adjusting the structure of citrus varieties in Meishan City.