Abstract:

The aims were to optimize apple planting areas, improve varieties, increase the output value of economic forests and fruits, revitalize rural economy, and achieve high-quality development of fruit industry. Taking the severe freezing damage process of apples in Longdong from April 28th to 29th, 2023 as an example, the hourly meteorological element changes during this process in representative areas of apple cultivation in Longdong, such as Qingcheng (Chicheng), Heshui (Hejiapan), Xifeng (Wenquan), Ningxian (Zaosheng, Panke), Zhengning (Gonghe), Zhenyuan (Fangshan), and Pingliang (Jingning) were used to study the correlation between the minimum temperature and low temperature duration of different varieties and different planting areas and the freezing grade of apple stamens by statistical methods. Temperature observation data from 8 national meteorological stations from 1971 to 2023 and apple development period data from Xifeng Agricultural Meteorological Experimental Station from 1994 to 2023 were also utilized. The results showed that frost damage had a relatively small impact on early maturing apple varieties such as Gala series, Micui, and Pink Lady, as well as late maturing apple varieties such as Ruiyang, Ruixue, and Ruixiang Hong in Longdong. It had a significant impact on the mid maturity variety Fuji. The apple cultivation area is more severe in mountainous and plain areas than in river areas and along the plateau. Due to climate change, the flowering period of apples in Longdong is advanced. When the temperature drops below -2℃, the degree of frost damage will increase with the decrease of temperature and the increase of duration. During the flowering period of apples, low temperature is the dominant factor affecting frost damage, while the minimum temperature and duration of low temperature are key indicators determining the degree of frost damage. If the temperature continues to fall below the tolerance limit of apple flowering, the occurrence and severity of frost damage will increase with the prolongation of low temperature, and will be verified by actual disaster situations.

Key words: apples from Longdong, climate warming, frost damage indicators, degree of frost damage, antifreeze measures, apple frost damage, meteorological factors, varietal differences, planting regions, low temperature impact