Abstract:

Based on meteorological observations from the Yecheng National Ordinary Meteorological Station (1991—2025), walnut phenological records, and survey data on freezing injury during the flowering period, this study analyzed the flower-bud freezing rate and yield, and used the climatic tendency rate method and the linear tendency method to clarify the meteorological driving mechanisms of flowering-stage freezing injury in Yecheng. The results show that the key meteorological factors include extreme low-temperature events (daily minimum temperature <6℃ and their duration), abrupt drops in ground surface temperature, compound weather systems with sandstorms (sandstorms accompanied by strong winds and snowfall), late spring cold spells, and frost events. In particular, temperature mutation features (e.g., daily minimum temperature and the magnitude of extreme low-temperature drops in the surface soil layer) and the superposition of hazards (co-occurrence of sandstorms and snowfall) markedly aggravate flower-bud freezing injury. These findings provide key threshold parameters and a basis for identifying compound disasters for monitoring and early warning of flowering-stage freezing injury in Yecheng County, and they also support the development of frost-protection and disaster-mitigation measures.

Key words: Yecheng walnut, flowering-stage freezing injury, extreme low temperature, temperature mutation, surface soil temperature, sandstorm, frost, late spring cold, hazard factors