Chinese Journal of Agrometeorology ›› 2020, Vol. 41 ›› Issue (06): 381-392.doi: 10.3969/j.issn.1000-6362.2020.06.005

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 Assessment on the Freezing Injury Risk during Apple Flowering in Liquan and Xunyi

 WANG Ming-chang, LIU Bu-chun, LIU Yuan, YANG Xiao-juan, HAN Shuai, QIU Mei-juan, LI qiong   

  1.  1.Institute of Environment and Sustainable Development in Agriculture, CAAS/National Engineering Laboratory of Efficient Crop Water Use and Disaster Reduction/Key Laboratory of Agricultural Environment, Ministry of Agriculture and Rural Affairs, Beijing 100081, China; 2.China Reinsurance Group Postdoctoral Research Station, Beijing 100033; 3. China Agricultural Reinsurance Pool, Beijing 100033
  • Received:2019-12-16 Online:2020-06-20 Published:2020-06-18
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Abstract:  Shaanxi province is an advantageous ecological area for apple cultivation and a high-risk area of freezing injury during flowering. Freezing injury during flowering has become one of the most serious natural disasters affecting the yield and quality of apples in Shaanxi. To assess the risk of flowering freezing injury of Fuji apples in two main apple-producing counties of Liquan and Xunyi, Shaanxi province, the daily average temperature was used to reconstruct the apple first flowering dates during 1967-2018 in Liquan and Xunyi, using the thermal time model. The daily minimum temperatures in the two sites during the same period were used to extract the last date of three freezing injury grades, in which the upper critical thresholds were-2, 0, and 2℃, respectively. The differences between the last date of three freezing injury grades and the first flowering date were defined as freezing injury risk indices. The linear tendency method was used to analyze variation trends in the first flowering date, last date of three freezing injury grades, and freezing injury risk indices. The results showed that the thermal time model could be used to reconstruct the first apple flowering dates in Liquan and Xunyi. The first apple flowering dates in Liquan and Xunyi advanced significantly from 1967 to 2018, with advance rates of 2.8d·10y-1 (P<0.01) in Liquan and 0.8d·10y-1 (P<0.05) in Xunyi, respectively. The last date of severe freezing injury in Liquan showed a significant advance trend with an advance rate of 3.3d·10y-1 (P<0.01), and the last dates of moderate and light freezing injury in Liquan showed no significant variation trends. There were no significant variation trends in the last dates of different freezing injury grades in Xunyi. The average first flowering date of apple in Liquan was on April 10(DOY 100), which was later than the average last date of light freezing injury on April 5(DOY 95), hence the risk of freezing injury in Liquan was low. The average first flowering date of apple in Xunyi was on April 17(DOY 107), which was later than average last date of severe freezing injury on April 3(DOY 93), but earlier than average last date of light freezing injury on April 28(DOY 118), hence the risk of freezing injury in Xunyi was higher than Liquan. There were no significant variations of freezing injury risk indices in Liquan and Xunyi, but the frequency of freezing injury risk index that higher than zero in Liquan and Xunyi increased, indicating that the freezing injury risk during apple blossoms was increasing.

Key words:  Agricultural insurance, Apple, First flowering date, Thermal time phenology model, Last day of freezing injury, Freezing injury risk index

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