Abstract
Experiments were carried out to make clear the process of devernalization of winter wheat, variety Norin No. 27. (1) The plants vernalized immediately after sowing for 30 or 40 days at 1°, 4°, 8°, 11°, and 15°C, respectively, were exposed to relatively high temperature of 12°, 18°, or 24°C for l0 days. The vernalization effect achieved at 1°C or 4°C were reversed markedly by the subsequent exposure to high temperature such as 18°C or 24°C. The effect obtained at 8°C or 11°C, on the other hand, were reversed a little by the same treatment. (2) The plants vernalized immediately after sowing at 1°C for 30 days were exposed to high temperature varying diurnally for 1 week. Among the plants which were exposed to various combinations of temperature being equal to mean temperature, the plants exposed to high temperature varying diurnally emerged the flag leaves on the same date as those exposed consecutively to a constant high temperature or emerged somewhat earlier than the latter. (3) The plants vernalized immediately after or 15 days after sowing at 2°C for 30 days were exposed to high temperature (25°C) under the light of different intensities. The vernalization effect was reversed markedly by the high temperature treatment under dark condition. This vernalization effect was reversed by the high temperature treatment more markedly under high light intensity than under low light intensity.
