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Cold injury of reproductive organs as influenced by low temperature and its duration under field conditions of loquat (Eriobntrya japonica Lindley cvs. Tsukumo (Jinun), Mogi (Mumok) and Tanaka (Jeonjung) was studied to provide basic data for minimizing cold injury. Cold injury of immature fruits in major cultivation areas was affected not by cultivars but mainly by minimum temperature of the area. The percent cold injury of immature fruits ranged 22.0∼-29.0%, 57.0∼85.0% and none in the area when minimum temperature was -5.3∼-5.6℃ , -8.1∼-9.2℃, and -2.1℃ or above, respectively. The cold injury of blossoms were 3.6∼9.3%, 7.1∼21.1% and 26.7∼44.0% when the reproductive organs was exposed to -3.8∼-4.2, -5.0∼-5.5 and -5.5∼-6.3℃ at the bearing parts of crown for 30 minutes ∼1 hour 30 minutes, 1 hour ∼3 hours and 30 minutes∼1 hour 30 minutes, respectively. When the air temperature of -3.0∼-3.5℃ at the bearing parts of craven continued for 1 hour 30 minutes ∼ 3 hours 30 minutes, 26.8∼39.3% of immature fruits were killed. Cold injury of reproductive organs by different parts in a crown was the highest at the upper part followed by the outer part and inner part. Cold injury to reproductive organs increased as their developmental stage progressed at the time of exposure to low temperature, being the highest in immature fruits and increased in the order of those at the stage of flower shedding, anthesis and right before anthesis. The temperature of fruit tissue recorded -2.3∼2.1℃ and -1.2℃ in upper part, outer part and inner part of crown when the air temperature of -1.5℃ continued for 30 minutes∼1 hour in loquat orchard. The fruits produced in upper and outer part of crown tended to have lower fruit temperature than those in inner part.
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