Effects of Meteorological Factors and Frost Injury on Flowering Stage of Apples and Pears Across Regions at Varying Altitudes

Recent meteorological variability in winter and spring complicates predicting and managing frost damage in apples and pears. This study investigated the relationship between frost injury during the flowering stages of apples (‘Hongro’ and ‘Fuji’) and pears (‘Wonwhang’ and ‘Niitaka’) and weather conditions across regions at varying altitudes. Orchards were categorized into coastal, inland, mid-mountainous, and mountainous regions, and flowering stages and frost injury were analyzed. The flowering period of apples, from the onset of blooming to full bloom, averaged approximately 15 days, which was about 3 to 5 times longer than that of pears. Furthermore, the total flowering duration of apples was 1.5 to 2.0 times longer than that of pears. Additionally, flowering exhibited a tendency to be delayed at higher altitudes. However, orchards situated in mid-mountainous regions experienced earlier flowering compared to those in other regions. Among the two apple cultivars, the average frost damage was more severe in central flowers than in lateral flowers and was relatively higher in ‘Fuji’ than in ‘Hongro’. In pears, frost damage was most prevalent in the first to fourth flowers within the inflorescence, with ‘Wonhwang’ exhibiting relatively greater susceptibility than ‘Niitaka’. Across different cultivation regions, severe frost damage was observed in orchards located in mid-mountainous areas for both fruit species and cultivars. The severity of frost damage followed the order mid-mountainous, mountainous, plain, and coastal regions. Minimum temperatures were lowest in mid-mountainous and mountainous regions, while daily temperature differences were largest in mid-mountainous regions. Meteorological analysis (1981 to 2022) revealed consistent trends, with an increase in daily temperature range in recent years. These findings highlight the vulnerability of mid-mountainous orchards due to flowering stages overlapping with coastal and plain regions, exposing them to lower temperatures and larger temperature differences. Further studies on temperature variability are essential to mitigate frost damage risks.