Abstract: Based on the meteorological monitoring data of blueberry (Vacciniumset.Cyanococcus) flowering period in four meteorological observation stations (and three surrounding meteorological observation stations) in Dandong area from 1991 to 2020,the temporal variation characteristics of minimum temperature were analyzed by mathematical statistics method.The daily minimum temperature T_min≤1 ℃ of blueberry flowering period was taken as the index of spring frost grade of blueberry.The risk index of spring frost disaster in blueberry flowering period was constructed and evaluated by four parameters :climate probability,standard deviation,occurrence frequency and intensity of spring frost.The results showed that:The climate tendency rate of the average minimum temperature during the flowering period of Dandong blueberries in the past 30 years showed an overall upward trend,with an average increase of 0.04 ℃ every 10 years.Among them,Fengcheng and Kuandian areas showed a downward trend,while Zhen'an and Donggang stations showed an upward trend.The northern mountainous area was more conducive to the formation of spring frost.The number of spring frost days during the flowering period of Dandong blueberry in the past 30 years showed an increasing trend,among which the number of mild spring frost days was up to 19.5 d (moderate 1.0 d,severe 0.8 d),and the climate tendency rate was more moderate and severe.The increasing trend was significant,with an average increase of 0.2 d per 10 years,mainly occurring in the Kuandian area of the northeastern mountainous area.The climatic probability of spring frost in Dandong blueberry flowering period in 30 a was significantly higher in the northern mountainous area (probability range 70.0%-86.6%) than in the southern coastal area (3.5%-10.1%),and the spatial distribution characteristics were basically consistent with the frequency and intensity of spring frost.The spring frost disaster risk index of Dandong blueberry flowering period can be divided into five grades:none,low,medium,high and extremely high risk.The extremely high and high risk areas are mainly concentrated in most areas of Kuandian and northern Fengcheng.The medium-risk areas are mainly concentrated in most areas of Fengcheng ;the low-risk areas are mainly concentrated in the south of Fengcheng and the north of Donggang,while the risk-free areas are mainly concentrated in Zhen'an District and the east of Donggang,which is consistent with the spatial distribution of the actual blueberry planting base.The results of the study obtained the risk areas of different levels of blueberry flowering spring frost disaster in each region,and provided a reference for scientific response to the blueberry flowering spring frost disaster.

Key words: Blueberry flowering, Frost, Disaster, Risk analysis