*3.3. Apple Flowering Monitoring Results*

A total of 1494 fruit tree images (3000 × 3000 pixels) were fed into S-YOLO-s for flower prediction to obtain the number variation and proportional variation under a time series (Figure 7b). Except for the decline in the number of buds caused by the late shooting date, the number of flowers in all three categories showed arching characteristics in line with the natural pattern for time variation. The average flower density at the peak of each stage was

55.687 on 3 April, 47.565 on 6 April, 118.183 on 9 April, and 17.522 flowers/tree on 15 April (Figure 7a) corresponding to 75.7%, 46.7%, 82.26%, and 49.58% of all flowers, respectively (Figure 7b). The flowering intensities of the orchard on different dates were 1.13%, 3.94%, 19.54%, 37.34%, 57.57%, 72.18%, 82.26%, 81.59%, 75.74%, 77.04%, 76.59%, 47.83%, and 12.18%. The experimental results show that the orchard was in the first flowering stage on 3 April, the middle flowering stage on 5 April, the full flowering stage on 7 April, and the last flowering stage on 15 April. In addition, based on the trend of the number of end-open flowers, it was predicted that only these would remain in the orchard from 17 to 18 April, which means that the orchard would be in the last flowering stage completely.

**Figure 7.** Flowering stage changes. (**a**) Changes in the daily number of flowers at each stage; (**b**) changes in the daily percentage of flowers at each stage.

This experiment demonstrated that with the help of an S-YOLO-s high-performance detector, it was possible to obtain time-series changes in the number and proportion of flowers. At the same time, it was possible to achieve the daily flowering intensity estimation and flower peak time determination at each stage, and finally, flowering information monitoring was realized. Notably, the results mentioned above were achieved by counting the detection results of single fruit trees; thus, S-YOLO-s is adequate for identifying the blooming phases of single fruit trees.
