Determination of freezing injury index in dormancy period of winter jujube trees cultivated by open-air
SUN Ai-liang
2021, 60(1):
42-45.
doi:10.14088/j.cnki.issn0439-8114.2021.01.009
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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 Tmin≤-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 Tmin,the duration,the duration days of Tmin≤-13.0 ℃,the duration days of Tmin≤-15.0 ℃ and the duration days of Tmin≤-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 Tmin,but also the duration days of Tmin≤-13.0 ℃,Tmin≤-15.0℃ and Tmin≤-17.0℃,respectively.When the extreme lowest temperature Tmin≤-13.0 ℃ lasts for 2 days,and Tmin≤-15.0 ℃ lasts for 1 day,slight freezing injury will occur;When Tmin≤-13.0 ℃ lasts for more than 3 days,and Tmin≤-15.0 ℃ lasts for 1 to 2 days,moderate frost damage will occur;When the extreme temperature Tmin≤-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.