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Chinese Journal of Applied Ecology ›› 2020, Vol. 31 ›› Issue (7): 2457-2463.doi: 10.13287/j.1001-9332.202007.026

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Changes of chilling and heat accumulation of apple and their effects on the first flowering date in the main planting areas of northern China

LIU Lu1, GUO Liang2*, LI Man-hua3, FU Wei-dong4, LUAN Qing5   

  1. 1Shaanxi Meteorological Service Center of Agricultural Remote Sensing and Economic Crops, Xi'an 710014, China;
    2State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling 712100, Shaanxi, China;
    3Shandong Provincial Meteorological Center, Jinan 250031,China;
    4Xinjiang Agricultural Meteorological Station, Urumqi 830002, China;
    5Shanxi Provincial Meteorological Center, Taiyuan 030006, China
  • Received:2019-11-28 Accepted:2020-04-30 Online:2020-07-15 Published:2021-01-15
  • Contact: E-mail: guoliang2014@nwsuaf.edu.cn
  • Supported by:
    This work was supported by the Central Asia Atmospheric Science Research Fund (CAAS202004).

Abstract: Studies on variations in chilling and heat accumulation in apple trees and their effects on first flowering date under climate change are important for guiding apple planting and productions. In this study, we carried out experiments in representative stations of apple planting areas in the northern China, including Fushan of Shandong, Wanrong of Shanxi, Xifeng of Gansu and Akesu of Xinjiang. The first flowering data and hourly temperature data during 1996-2018 were used to calculate the daily chilling and heat accumulation units by applying the dynamic model and growing degree hour model. Partial least squares regression (PLS) correlated daily chilling and heat units with the first flowering dates was used to identify the chilling and heat accumulation periods for apple flowering. We evaluated the impacts of temperatures during these periods on apples' flowering. Our results showed that the chilling accumulation period of apple trees in the examined sites started at October 1, ended in late February or mid-March, with chilling accumulations of 74.1-89.3 CP (chill portion). The heat accumulation periods were from late January to the first flowering dates with the heat accumulation of 4010-5770 GDH (growing degree hour). The chilling accumulation at Xifeng and Akesu was correlated positively with mean temperature during the respective accumulation period, with 3.8 and 5.0 CP enhancement following 1 ℃ increase during the accumulation period. Heat accumulation at all stations correlated positively with mean temperature during the respective accumulation period, with 725-967 GDH enhancement following a 1 ℃ increase during the accumulation period. Compared to the effects of chilling accumulation on tree flowering, the first flowering data of apples in the main planting areas were mainly affected by mean temperature during the heat accumulation period. Climate warming is beneficial for apple blossom and production in the areas with low mean temperature during the chilling accumulation period.

Key words: Fuji apple, chilling requirement, heat requirement, first flowering date