Abstract
1. On the grade of the progress of the thermo-phase and high night-temperature treatment of wheat plants, the following two experiments were carried. Exp. I: The effects of the treatment before and after the initiation of the young panicle was studied using the spring wheat (Saitama-No. 27) and the winter wheat (Akasabi-Shirazu-No. 1). Exp. 2: The effects of the treatment upon the winter wheat (Akasabi-Shirazu-No. 1) which varies in the grade of the vernalization was studied. 2. The materials were treated in two green-houses, the one being heated during night time to raise the night-temperature average about 6°C higher than the other one or control. The plants were adequately managed. 3. The development of the wheat plants were promoted by the high night-temperature treatment, but the grade of the development of the spring wheat was much larger than winter wheat. In case of the winter wheat, the promotive effect was observed when only the plants passed through the thermo-phase, the development of the plants when incompletely vernalizes was delayed. 4. The growth rate of the wheat plant was promoted by the treatment. In case of the spring wheat, the numbers of leaf was increased by the treatment before the initiation of young panicle, the height of plant was increased at the initiation of the young panicle, the tiller increased after the initiation of the young panicle. In case of the winter wheat, The same results were obtainned but not so clear. 5. The numbers of ear, the length of ear and the numbers of grain per ear were decreased by the treament after the initiation in spring wheat. The ear-weight and the grain-numbers per ear were decreased in winter wheat.
