This study was carried out to verify the effect of increasing the ambient temperature around apple trees by directly blowing warm-air under the slender spindle apple training system using an agricultural warm-air blower and ducts used in plastic house cultivation to develop late frost damage reduction technology during the blooming season. The temperature increase effect around apple trees owing to the operating warm-air blowing ducts was most evident at a height of 30 cm from the ground surface. At this height, the branch ducts made of Oxford fabric and Solartex showed a raised ambient temperature of about 2.6oC and 1.1oC, respectively. However, the temperature rising effect at a height of 130 cm and 230 cm from the ground surface owing to the operating warm-air blowing ducts was not distinct compared to that in the control. The effect of raising ambient temperature around apple trees through the operation of warm-air blowing ducts was found to be greater as the ambient temperature did not severely drop below the freezing temperature. Damage to the central flower in the apple inflorescence at the pink stage was significantly reduced in the warm-air blowing ducts made of Oxford fabric (42.8%) compared to that in the control (73.2%). However, the damage to other flowers except the central one was not significant compared to that in the control. The fruiting rate of the central and other flowers in the apple inflorescence depending on the operating warm-air blowing ducts was significantly increased compared to that in the control. The fruiting rates of central and other flowers depending on the ducts materials, such as Oxford fabric, and Solartex, and that of the control were 38.3%/82.7%, 31.4%/82.7%, and 0.5%/61.1%, respectively. In conclusion, in the case of open-field apple orchards, if the warm-air blowing duct is installed close to the laterals where frost damage mainly occurs in the slender- spindle dense cultivation system, the damage caused by late frost in the vicinity of blooming time can be reduced to some extent.

서 언
재료 및 방법
    시험장소 및 온풍덕트 설치
    조사내용
    통계분석
결과 및 고찰
    온풍덕트 가동에 따른 수고별 온도변화
    온풍덕트 가동에 따른 화기 피해율 및 착과율
적 요
ACKNOWLEDGMENTS
REFERENCES

• 송주희(국립한국농수산대학교 원예학부) | Ju Hee Song (Division of Horticulture, Korea National University of Agriculture and Fisheries, Jeonju 54874, Republic of Korea)
• 박천완(국립농업과학원 수확후관리공학과) | Chun Wan Park (Division of Postharvest Engineering, National Institute of Agricultural Sciences, Wanju 55365, Republic of Korea)
• 김승희(국립한국농수산대학교 원예학부) | Seung Heui Kim (Division of Horticulture, Korea National University of Agriculture and Fisheries, Jeonju 54874, Republic of Korea) Corresponding author
• 곽용범(국립한국농수산대학교 원예학부) | Yong-Bum Kwack (Division of Horticulture, Korea National University of Agriculture and Fisheries, Jeonju 54874, Republic of Korea) Corresponding author