Abstract: In order to study the effect of high temperature at seedling stage on the intrinsic quality of strawberry fruits in the greenhouse, and then to conduct comprehensive evaluation of different experimental treatments to establish a comprehensive evaluation model of intrinsic quality of strawberry fruits. In 2018 and 2019, strawberry seedlings were stressed with different high temperature (32, 35, 38 and 41℃) and different stress days (2, 5, 8 and 11d), and then transplanted to Venlo glass greenhouse for normal cultivation experiments, with normal greenhouse cultivation as a control. Based on the differences in fruit intrinsic quality indicators under each treatment, the comprehensive score of each experimental treatment determined by the fuzzy comprehensive evaluation method, and by analyzing the relationship between the comprehensive score and different stress temperatures and stress days, a comprehensive evaluation model of fruit intrinsic quality was constructed. Among them, the data obtained in 2018 were used for model construction, and in 2019 were used for model verification. The results showed that the effects of different stress days on the vitamin C, soluble sugar content, titratable acid content and anthocyanin of strawberry fruits were different under high temperature. The weights of the four intrinsic qualities of strawberries are titratable acid (0.33)> anthocyanin (0.25)> vitamin C (0.23)> soluble sugar (0.19). The score of the fuzzy comprehensive evaluation showed that the comprehensive score of the intrinsic quality of the fruit was highest at 8 days and 11 days at 35℃, and 2 days and 5 days at 38℃ (all greater than 0.8). The comprehensive fruit quality scores were medium (between 0.6 and 0.8) at 2d and 5d at 35℃ and 32℃ treatment, and the lowest comprehensive fruit quality scores (between 0 and 0.6) under 38℃ treatments for 8 days and 11 days and 41℃ treatment. The determination coefficients (R2) of the built-in comprehensive quality model for the simulated and measured values ​​of greenhouse strawberry comprehensive quality were 0.86, the root mean square error (RMSE) was 0.01, and the relative error (RE) was 0.06%. Therefore, a certain degree of high temperature treatment (within 11 days at 35℃ or within 5 days at 38℃) in the greenhouse strawberry seedling stage will help to improve the comprehensive intrinsic quality and the model established can predict the comprehensive intrinsic quality of the greenhouse strawberry under high temperature at the seedling stage, which has a guiding significance for the regulation of the strawberry greenhouse temperature environment.

Key words: Strawberry, High temperature in the seedling stage, Fruit quality, Evaluation model, Fuzzy evaluation method