Abstract: By investigating the occurrence of freezing injury in winter dormancy period of winter jujube trees cultivated in the open air from 1990 to 2019 in Huanghua city,Hubei province,and comparing the occurrence of strong cooling weather process with extreme lowest air temperature T_min≤-13.0 ℃ in the same period,five meteorological factors,which may have a great influence on the freeze injury of winter jujube trees during dormancy,were selected,including the extreme lowest temperature T_min,the duration,the duration days of T_min≤-13.0 ℃,the duration days of T_min≤-15.0 ℃ and the duration days of T_min≤-17.0 ℃.Four significant factors were selected by stepwise regression method to establish the function equation,and each factor was analyzed in combination with the occurrence of freeze injury in dormancy period of winter jujube trees over the years.The agrometeorological index of freeze injury in dormancy period of winter jujube trees was obtained.The results showed that the influence factors of extreme weather on the freeze injury of winter jujube were not only T_min,but also the duration days of T_min≤-13.0 ℃,T_min≤-15.0℃ and T_min≤-17.0℃,respectively.When the extreme lowest temperature T_min≤-13.0 ℃ lasts for 2 days,and T_min≤-15.0 ℃ lasts for 1 day,slight freezing injury will occur;When T_min≤-13.0 ℃ lasts for more than 3 days,and T_min≤-15.0 ℃ lasts for 1 to 2 days,moderate frost damage will occur;When the extreme temperature T_min≤-15.0 ℃ lasts for more than 2 days or the extreme minimum temperature ≤-17.0 ℃ lasts for more than 1 day,severe frost damage will occur.The established indexes of frost damage were backtested.Combined with the literature,the frost damage of winter jujube trees producing areas such as Tianjin city and Shandong province was examined.The comprehensive fitting rate reached 78.5%,which indicated that the established indexes had practical production guidance significance.

Key words: winter jujube trees, dormancy period, minimum temperature, frost damage index