Abstract
Plants of radish ‘Taibyo-sohbutori’ were exposed to the low temperature treatment (6°C) with an interruption of high temperature (17, 24 or 30°C) for 4, 6 or 8 hr per day, respectively. We applied a new index “flower formation index” to the data of floral induction after the treatment in order to estimate hours per day contribute to devernalization and vernalization. According to “flower formation index”, the inflorescence formation suppressed under the high temperature treatment at 24°C for 6 to 8 hr per day, and this suppression markedly occurred at higher temperature of 30°C. In the case of intermittent low temperature treatment, by calculating “estimated hours per day contribute to vernalization and devernalization”, it was possible to recognize the effect of high temperature interruption during low temperature treatment. We supposed that the vernalization effect by a low temperature treatment would be counteracted by 30-40%, if the plants are exposed to 24°C for 8 hr or 30°C for 6 hrs per day during the low temperature treatment.
