• Journal of Bio-Environment Control
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• v.30 no.4
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• pp.320-327
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• 2021

Freezing damage to fruit trees is frequently occurring due to cold in winter and low temperature in spring to abnormal weather caused by global warming. In particular, the freezing injury of deciduous fruit trees is highly dependent on the developmental stages of the flower buds. And the cold resistance is weakened as the growth progresses, so it is most vulnerable period from flowering to petal fall(post-bloom). Therefore, this study was conducted to analyze the cause of the freezing injury caused by severe low temperature to 'Fuji', which has a late flowering period more than 'Hongro' in April 2020. We investigated freezing injury rate in 'Fuji' and 'Hongro' apple trees damaged by natural low temperature at Boeun-gun, Chungbuk province in Korea. In addition, flower buds in the same developmental stage (tight cluster) were treated artificially low temperature to investigate the injury rate for accurate comparative analysis between varieties, and to analyze the soluble sugar and hormone contents in the flower buds. As a result of survey in natural low temperature, 'Fuji' had a higher injury rate than 'Hongro' in both orchards, and in particular, B orchard 'Fuji' had the highest injury rate of 60.5%. Also there were significantly difference in the freezing injury rate between 'Fuji' and 'Hongro' in artificially low temperature treatments. As a result of analyzing the soluble sugar contents in 'Hongro' was higher than 'Fuji'. Also ABA, IAA and SA contents were more increased in the damaged tissue than in the normal flower buds by low temperature treatments. Consequently, it was assumed that the freezing injury was closely related to soluble sugar contents in the flower buds. In particular, the freezing injury rate was negatively correlated with the sorbitol contents.