Interaction of vernalization, photoperiod and high temperature in flowering of Arabidopsis thaliana (L.) HEYNH.

Flowering of Arabidopsis thaliana (L.) HEYNH., var. “Stockholm”, plants, raised from vernalized seeds, may be modified by the photoperiodic conditions or a short (1 week) exposure to high temperature (32°C) following vernalization, depending on the duration of the cold treatment. When vernalization is partial (1 to 4 weeks at 4°C), both short days (8hr light) and high temperature have a devernalizing effect, but when the cold requirement has been fully satisfied, after 5 to 6 weeks at 4°C, devernalization is no longer possible. There is no interaction between photoperiod and high temperature. Fully vernalized plant flower in both long and short days, although flowering is delayed in short days. This delay is not a photoperiodic effect, however, but may be ascribed to the decreased radiant energy available in an 8-hr photoperiod. Thus, fully vernalized Arabidopsis plants are day-neutral.