Abstract:  In the five main production areas of Fuji apple in China, Fushan(in Shandong province and belongs to the Around Bohai bay production area), Sanmenxia(in Henan province and belongs to the old Yellow River production area), Xifeng(in Gansu province and belongs to the Loess Plateau production area), Zhaotong(in Yunnan province and belongs to the southwest cold highland production area), Akesu(in Xinjiang Uygur Autonomous Region and belongs to the Xinjiang production area)were selected as representative sites. Using SPSS statistical software, the meteorological factors affecting Fuji apple flowering were analyzed and screened, and the flowering simulation models of Fuji apple were constructed. The mean absolute error (MAE) and graded weighted full score method were used to test the models, and the epitaxial test of the models were carried out by using the phenological observation data of 12 sites around the representative sites. On this basis, using the meteorological data of 416 sites in China's apple production areas from 1981 to 2018, the first and terminal flower of Fuji apple were simulated year by year. The results showed that, the full scores of single site tested were 66.7%-100.0%, the mean absolute errors (MAE) were 0.4-3.4d, and the MAE of epitaxial tests were 1.2?5.1d. From 1981 to 2018, the flower stages of Fuji apple in China have three characteristics: large time difference, early change trend, and the dividing point of early change around 1997. Zhaotong’s average first flower was the earliest, at 82.0d (March 21), Xifeng’s average first flower was the latest, at the 109.0d (April 19), with a difference of 27.0d. Zhaotong’s average terminal flower was the earliest too, at 101.0d (April 11), Xifeng’s average terminal flower was the latest too, at 119.0d (April 29), with a difference of 18.0 days. The early change range of Fuji Apple's first flower, in Zhaotong was 4.5d·10y-1, which was the largest, and in Fushan was 1.6d·10y-1, which was the smallest. The early change range of Fuji apple's terminal flower, in Zhaotong was 3.8d·10y-1, which was the largest too, and in Akesu was 1.2d·10y-1, which was the smallest. On the whole, the spatial distribution characteristics of the flower stage of Fuji apple in China were gradually postponed from south to north. In the southwest cold highland production area, the average first flower was before 90 days (March 31) and the average terminal flower was before 105 days (April 15). In the old Yellow River production area, the average first flower was between 91-100d (April 1 to 10), and the average terminal flower was between 106-110d (April 16-20). In the Loess Plateau production area, the average first flower was between 101-110d (April 11 to 20), and the average terminal flower was between 111-120d (April 21 to 30). In the Xinjiang production area, the average first flower was between 96-115d (April 6 to 25), and the average terminal flower was between 106-125d (April 16 to May 5).In the Around Bohai bay production area, the average first flower was between 101-120d (April 11 to 30), and the average terminal flower was between 111-130d (April 21 to May 10).

Key words:  Main apple production area, Fuji apple, First flower stage, Terminal flower stage, Flower stage simulation