Abstract
Pregerminated seeds of radish cultivar‘Ohkura’were exposed to 0, 3, 6, 9 and 12°C for 15, 20, 25 and 30 days under dark and the seedlings were grown for 50 days in an artificially-lit growth chamber. The inflorescence was formed at treatment temperatures from 0 to 9°C with the most effective temperature at 6°C. The number of nodes with lateral inflorescence was also greater and the number of nodes below the terminal inflorescence was fewer at 6°C than at other temperatures. Seedlings of‘Ohkura’exposed to 0, 3, 6, 9 12 and l5°C for 7, 14, 21, 28 and 35 days had broader temperature range for inflorescence formation than that pregerminated seeds. The most effective temperature was between 3 and 9°C. Seedling of‘Wakayama’grown under the same conditions as‘Ohkura’had similar responses with those of‘Ohkura’, but had higher percentages of plants with terminal inflorescence and fewer number of nodes below the terminal inflorescence. We applied“flower formation index”introduced by Saito and Saito (2001) to express the effect of temperature and duration of vernalization treatment. This index quantitatively explained these effects on inflorescence formation in radish plants.
