Abstract: 【Objective】This study aimed to establish a comprehensive evaluation model in fruit quality, clarify the comprehensive grade of fruit quality and their corresponding meteorological characteristics from different Newhall Navel orange (Citrus sinensis [L.] Osb. cv. Newhall) orchards in China, and provide a reference for the ecological environment adaptability and suitable planting. 【Methods】Twenty three Newhall orchards in different ecological environments of China were selected to measure fruit external and internal quality indicators. Correlation analysis, principal component analysis and cluster analysis were used to identify the core indicators, and the comprehensive evaluation models of fruit quality were established by analytic hierarchy process (AHP), principal component analysis (PCA) and fuzzy comprehensive appraisal (FCA), respectively. The optimal algorithm model and fruit grade classification threshold were determined and verified with sensory quality evaluation. Meanwhile, the comprehensive quality grades 

and the characteristics of corresponding ecological factors of Newhall navel orange fruit from different producing areas were explored. 【Results】The fruit comprehensive quality of 23 Newhall orchards showed obvious regional characteristics. The fruit in southern Jiangxi and southern Hunan have higher total soluble solid and solid acid ratio, while the fruit in western Hunan and the upper and middle reaches of the Yangtze River have better fruit external color indexes and higher titratable acid. The quality indexes are correlated to varying degrees. Five core indexes were selected by principal component analysis combined with cluster analysis, including comprehensive color index, fruit weight, soluble solids, solid acid ratio and vitamin C content. At the same time, AHP model was determined as the comprehensive evaluation model of fruit quality with the best fitting degree of sensory quality index: Y (comprehensive value) = 0.06× comprehensive color index + 0.26× single fruit weight +0.16× soluble solid content +0.42× solid acid ratio +0.11× vitamin C content (standardized value). The comprehensive fruit quality indicators of different Newhall orchards were ranked, and the classification threshold was determined as follows: ≥0.60 was the first—class orchards, mainly concentrated in southern Jiangxi, southern Hunan and eastern Guangdong, with active accumulated temperature, effective accumulated temperature, maximum sunshine hours and surface temperature; 0.45—0.60 was the second—class orchards, mainly concentrated in northern Guangxi and western Fujian, characterized by higher temperature accumulation and rainfall; 0.30—0.45 was the third—class orchards, mainly concentrated in western Hunan and the middle and upper reaches of the Yangtze River, with relatively lower rainfall and temperature accumulation; <0.30 was the fourth—class orchards, mainly distributed in southern Zhejiang, with the highest rainfall. 【Conclusion】The core indicators of the comprehensive quality of citrus fruits were identified by PCA, and the AHP model with the optimal for the Newhall fruit comprehensive evaluation by combining the eigenvalues of each principal component to achieve automatic assignment of AHP judgment matrix. The ecological factors of different grades of orchards were significantly different. These results provide algorithms and data support for the development of the decision system based on " suitable planting "of citrus varieties in different ecological environment.

Key words: Newhall navel orange, fruit quality, comprehensive evaluation, environmental adaptability