Identifying the Diurnal Sensitivity of Poinsettia Flowering to High Temperatures
This study aimed to determine the relative sensitivity of poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch ‘Prestige Red’) flowering to high temperatures within a 24-hour cycle. For the first experiment, two growth chambers were used, one provided a moderate-temperature environment of 22 °C, and...
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American Society for Horticultural Science (ASHS)
2025-04-01
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| Series: | HortScience |
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| Online Access: | https://journals.ashs.org/hortsci/view/journals/hortsci/60/5/article-p709.xml |
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| author | Paul D. Millar Ana Maria Borda James E. Faust |
| author_facet | Paul D. Millar Ana Maria Borda James E. Faust |
| author_sort | Paul D. Millar |
| collection | DOAJ |
| description | This study aimed to determine the relative sensitivity of poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch ‘Prestige Red’) flowering to high temperatures within a 24-hour cycle. For the first experiment, two growth chambers were used, one provided a moderate-temperature environment of 22 °C, and the other provided a high-temperature environment of 28 °C. The day length and night length in each chamber were each 12 hours. Plants were moved between chambers to provide different temperature treatments over a 2-week period. During this time, plants were exposed to high temperatures during the first 6 hours of the day, the last 6 hours of the day, the first 6 hours of the night, or the last 6 hours of the night. Additional treatments included plants that were exposed to the high-temperature environment for 12 hours of the night or day period and plants that were exposed to the moderate-temperature or high-temperature environments for the entire 24 hours. After the treatment period, all plants were moved to a 22 °C greenhouse and a 12-hour night length until flowering data were collected. The last 6 hours of the night had the highest relative sensitivity to high temperatures, followed by the first 6 hours of the day. A second experiment was conducted to provide temperatures at a broader range and higher resolution (e.g., 24, 26, 28, 30, 32 and 34 °C) while testing our hypothesis that poinsettia is highly sensitive to high temperatures during the last 6 hours of the night and the first 2 hours of the day. Plants exposed to high temperatures (≥26 °C) during the last 6 hours of the night and the first 2 hours of the day displayed a greater delay in flowering compared with plants that received 24 °C for 24 hours per day. This project demonstrated that heat delay of poinsettia is highly sensitive to temperatures ≥26 °C that occur during the last 6 hours of the night and the first 2 hours of the day during flower initiation (the first 2 weeks of inductive photoperiods) under natural day length conditions (12-hour night length). |
| format | Article |
| id | doaj-art-9c1515d119fd44cbb5c52d4f963e7df3 |
| institution | OA Journals |
| issn | 2327-9834 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | American Society for Horticultural Science (ASHS) |
| record_format | Article |
| series | HortScience |
| spelling | doaj-art-9c1515d119fd44cbb5c52d4f963e7df32025-08-20T01:55:51ZengAmerican Society for Horticultural Science (ASHS)HortScience2327-98342025-04-01605https://doi.org/10.21273/HORTSCI18419-25Identifying the Diurnal Sensitivity of Poinsettia Flowering to High TemperaturesPaul D. Millar0Ana Maria Borda1James E. Faust2Department of Plant and Environmental Sciences, Clemson UniversityDepartment of Plant and Environmental Sciences, Clemson UniversityDepartment of Plant and Environmental Sciences, Clemson UniversityThis study aimed to determine the relative sensitivity of poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch ‘Prestige Red’) flowering to high temperatures within a 24-hour cycle. For the first experiment, two growth chambers were used, one provided a moderate-temperature environment of 22 °C, and the other provided a high-temperature environment of 28 °C. The day length and night length in each chamber were each 12 hours. Plants were moved between chambers to provide different temperature treatments over a 2-week period. During this time, plants were exposed to high temperatures during the first 6 hours of the day, the last 6 hours of the day, the first 6 hours of the night, or the last 6 hours of the night. Additional treatments included plants that were exposed to the high-temperature environment for 12 hours of the night or day period and plants that were exposed to the moderate-temperature or high-temperature environments for the entire 24 hours. After the treatment period, all plants were moved to a 22 °C greenhouse and a 12-hour night length until flowering data were collected. The last 6 hours of the night had the highest relative sensitivity to high temperatures, followed by the first 6 hours of the day. A second experiment was conducted to provide temperatures at a broader range and higher resolution (e.g., 24, 26, 28, 30, 32 and 34 °C) while testing our hypothesis that poinsettia is highly sensitive to high temperatures during the last 6 hours of the night and the first 2 hours of the day. Plants exposed to high temperatures (≥26 °C) during the last 6 hours of the night and the first 2 hours of the day displayed a greater delay in flowering compared with plants that received 24 °C for 24 hours per day. This project demonstrated that heat delay of poinsettia is highly sensitive to temperatures ≥26 °C that occur during the last 6 hours of the night and the first 2 hours of the day during flower initiation (the first 2 weeks of inductive photoperiods) under natural day length conditions (12-hour night length).https://journals.ashs.org/hortsci/view/journals/hortsci/60/5/article-p709.xmlcircadian rhythmeuphorbia pulcherrimaflower initiationheat delayphotoperiod |
| spellingShingle | Paul D. Millar Ana Maria Borda James E. Faust Identifying the Diurnal Sensitivity of Poinsettia Flowering to High Temperatures HortScience circadian rhythm euphorbia pulcherrima flower initiation heat delay photoperiod |
| title | Identifying the Diurnal Sensitivity of Poinsettia Flowering to High Temperatures |
| title_full | Identifying the Diurnal Sensitivity of Poinsettia Flowering to High Temperatures |
| title_fullStr | Identifying the Diurnal Sensitivity of Poinsettia Flowering to High Temperatures |
| title_full_unstemmed | Identifying the Diurnal Sensitivity of Poinsettia Flowering to High Temperatures |
| title_short | Identifying the Diurnal Sensitivity of Poinsettia Flowering to High Temperatures |
| title_sort | identifying the diurnal sensitivity of poinsettia flowering to high temperatures |
| topic | circadian rhythm euphorbia pulcherrima flower initiation heat delay photoperiod |
| url | https://journals.ashs.org/hortsci/view/journals/hortsci/60/5/article-p709.xml |
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