2019 ASHS Annual Conference

The unexpected extraordinary cold wave occurs irregularly in Korea due to abnormal climate change. This unusual climate affects on the growth and development of citrus tree and fruit. This research was conducted to investigate the cold tolerance on citrus cultivars and the mechanism of frost damage by the analysis of tissue change on low temperature conditions. The exothermal point was determined by temperature measurement sensor on surface of leaves in seconds until –30℃. The value of median lethal temperature(LT50) was determined by the amount of the produced electrolyte after the treatments under 6 different low temperature conditions for 1 hour respectively. And LT50 was calculated by Gompertz function equation after the integration of the measured values. Soluble solid content was increased, and O7 gene was down-regulated in leaves of the cold acclimated citrus cultivars. That is, the results shows the frost damage affects on the physiological changes of citrus tree, growth disorder, and fruit quality.