• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.2
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• pp.76-82
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• 2010

This study was carried out to compare and analyze control methods of the sunburn occurrence that affected 'Fuji'/M.9 planting systems in Korea from 2001 to 2003. It is very important to control temperature of the surface of fruits, because sunburn may occur when the temperature of fruit surfaces reaches $40^{\circ}C{\sim}45^{\circ}C$ due to high air temperature and sunlight during growing periods. As control methods of the sunburn occurrence, white coating materials such as $CaCO_3$ or kaolin were applied four times at two-week intervals from late June, and microspraying of water was conducted when air temperature was over $31^{\circ}C$ from late July to mid-August. Both methods were effective for preventing the sunburn occurrence and improving fruit quality by decreasing peel's temperature of fruits and increasing photosynthesis.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.261-269
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• 2022

This study was carried out to predict fruit surface temperature (FST) causing sunburn symptoms and assess the correlation between solar radiation and FST in satusma mandarin (Citrus unshiu Marc. 'Iwasaki'). And to reduce sunburn when ambient temperature was at 31℃, sprinkler system was repeated spraying every at 5 minutes of 30 minutes intervals and 1% calcium carbonate and 4% kaolin solution applied on citrus tree three times to investigate quality and sunburn of fruits. It showed highly significant positive correlation between FST and solar radiation (R = 0.788, p < 0.01), The FST increased up to 16℃ than ambient temperature at daytime. To estimate FST, a linear model y = 0.099 × (air temperature) + 0.018 × (solar radiation) + 20.779 (R = 0.687, p < 0.01) was derived. The canopy temperature of citrus trees was 5.1℃ lower in sprinkler system than in control. The incidence of sunburn showed at 2.1% in sprinkler system twice lower than in control and there was different significance. Fruit quality was similar between treatments. In conclusion, sunburn can be reduced by reflecting sunlight or downing of FST through sprinkler system.