본 연구는 고온기 포인세티아 ‘플레임’의 안정적 재배를 위한 주간온도 관리기준을 제시하고자 수행되었다. 야간 온도를 26℃로 고정한 야간 고온 조건에서 주간 온도를 30℃, 33℃, 36℃, 39℃로 7주간 처리하였다. 39/26℃ 처리구는 5일 이내 전 개체가 고사하였고, 36/26℃ 처리구의 생존율은 60%로 감 소하였다. 초장, 초폭, 분지수는 30/26℃와 33/26℃ 처리구 간에 유의적인 차이가 없었으나, 36/26℃ 처리구는 30/26℃에 비해 각각 29.5%, 30.9%, 27.5% 감소하였다. 신엽 발생은 온도 상승에 따라 급격히 줄어들어 36/26℃에서는 평균 2.3 개로 거의 발생하지 않았다. 27/20℃에 비해 고온처리구에서 엽장은 20.3%~37.6%, 엽폭은 56.4%~57.1% 감소하여 엽장/ 엽폭 비가 증가하였다. F v/Fm과 NDVI는 처리간 큰 차이가 없었 으나, ELP는 36/26℃에서 38%로 증가하였다. 광합성 속도는 27/20℃에서 가장 높았고, 30/26℃와 33/26℃는 유사하였으 나 36/26℃ 처리구는 1,000μmol·m-2·s-1의 광도에서도 0에 가까웠다. 또한 36/26℃에서 증산속도와 세포간 CO₂ 농도가 유의적으로 높게 나타났다. 따라서 주간 33℃ 이상에서 포인세 티아 ‘플레임’은 생리적･형태적 장해가 급격히 증가할 수 있으 므로, 고온기 안정적인 재배를 위해서는 주간 온도를 최소한 33℃ 이하로 관리할 필요가 있을 것으로 판단된다.

This study aimed to propose a daytime temperature management strategy for poinsettia cultivation during high-temperature periods. To this end, high night temperature conditions were imposed with a constant night temperature of 26°C, and day temperatures of 30°C, 33°C, 36°C, and 39°C were applied for seven weeks. For comparison, a control treatment was maintained in a greenhouse at 27°C/20°C (day/night) during the same period. All plants in the 39°C/26°C treatment died within five days, and survival decreased to 60% under the 36°C/26°C treatment. Plant height, width, and branch number did not differ significantly between the 30°C/26°C and 33°C/26°C treatments; however, these parameters decreased by 29.5%, 30.9%, and 27.5%, respectively, at 36°C/26°C compared with 30°C/26°C. The number of newly formed leaves declined sharply with increasing day temperature, averaging only 2.3 leaves at 36°C/26°C, indicating minimal vegetative growth. Relative to the 27°C/20°C control, leaf length and width decreased by 20.3%–37.6% and 56.4%–57.1%, respectively, under high-temperature treatments, resulting in an increased leaf length-to-width ratio and narrower leaf morphology. The normalized difference vegetation index and maximum quantum yield of photosystem II (Fv/Fm) showed slight variation among treatments, whereas electrolyte leakage percentage increased markedly to 38% at 36°C/26°C. Net photosynthetic rate was highest at 27°C/20°C, remained similar between the 30°C/26°C and 33°C/26°C treatments, but declined to zero at 36°C/26°C even under a light intensity of 1,000 μmol·m-2·s-1. In addition, transpiration rate and intercellular CO2 concentration were significantly higher at 36°C/26°C. These results indicate that both physiological and morphological stress in poinsettia intensifies when daytime temperatures exceed 33°C. Therefore, maintaining daytime temperatures below 33°C is recommended for stable poinsettia production during high-temperature seasons.

서 언
재료 및 방법
    실험 재료 및 고온 처리
    생육 특성 조사
    통계분석
결과 및 고찰
초 록
사 사
References

• Hyun Hwan Jung(Floriculture Research Division, National Institute of Horticultural and Herbal Science, RDA, Wanju 55365, Korea) | 정현환 (농촌진흥청 국립원예특작과학원 화훼기초기반과) Corresponding author
• Jung-Nam Suh(Floriculture Research Division, National Institute of Horticultural and Herbal Science, RDA, Wanju 55365, Korea) | 서정남 (농촌진흥청 국립원예특작과학원 화훼기초기반과)
• Yun-Im Kang(Floriculture Research Division, National Institute of Horticultural and Herbal Science, RDA, Wanju 55365, Korea) | 강윤임 (농촌진흥청 국립원예특작과학원 화훼기초기반과)
• Myung Suk Ahn(Floriculture Research Division, National Institute of Horticultural and Herbal Science, RDA, Wanju 55365, Korea) | 안명숙 (농촌진흥청 국립원예특작과학원 화훼기초기반과)
• Ho Jin Lee(Floriculture Research Division, National Institute of Horticultural and Herbal Science, RDA, Wanju 55365, Korea) | 이호진 (농촌진흥청 국립원예특작과학원 화훼기초기반과)
• Ju Seok Yang(Floriculture Research Division, National Institute of Horticultural and Herbal Science, RDA, Wanju 55365, Korea, 2Department of Environmental Horticulture and Landscape Architecture, Dankook University, Cheonan 31116, Korea) | 양주석 (농촌진흥청 국립원예특작과학원 화훼기초기반과, 단국대학교 환경원예, 조경학과)
• Ae Kyung Lee(Department of Environmental Horticulture and Landscape Architecture, Dankook University, Cheonan 31116, Korea) | 이애경 (단국대학교 환경원예, 조경학과)