Fine Zoning of Freezing Damage Risk of Apple Flowering Period in Zhidan County Based on GIS

Used the minimum temperature data from April to May of 1960 to 2022 of Zhidan weather station and temperature observation data of regional weather station and orchard weather station from October 2021 to May 2022, field investigation, mathematical statistics, random forest regression, and natural breakpoint method were used for temperature statistical analysis and Zhidan apple flowering freezing damage risk zoning．Results showed that apple freezing damage in Zhidan mainly appeared on April 11-17, 24-26 and May 13-15, and appeared the most frequently on April 11-17．Average freezing weather was about two years．Extreme minimum temperature of apple flowering period was low in the 1960s, 1970s, 2000s and 2010s, and freezing damage was serious, while extreme minimum temperature of apple flowering period was highed in the 1980s and 1990s, and freezing damage was light．Valley land, due to accumulation of cold air, low temperature, and high risk of freezing damage, was not suitable for planting apples．When altitude was from 1200 to 1430 m, temperature changed sharply, and risk areas of heavy, medium, and light coexisted．When altitude was above 1430 m, and risk of freezing damage was relatively low．At present, about 67.2% of orchards in Zhidan were light risk areas, 25.3% were medium risk areas and 7.5% were heavy risk areas．Planting structure of orchards in heavy risk area should be adjusted, and orchards in medium risk area should strengthen prevention of freezing injury．