抄録
The experiments were carried out to follow the process of vernalization in winter wheat plants, var. Norin no. 64, under the field condition in late autumn and winter seasons. At successive stages, some of the growing plants in field were removed to the continuous light condition under the temperature of about 20°C, and the affected degree by natural vernalization in the plants was estimated by counting the number of leaves newly formed before flowering in the main stem, subtracting the number of determinate leaves at the time of the removing from the final leaf number. It was found that the vernalization progressed almost to the completion during one or one and a half month from sowing time. The results indicated that the vernalization under the field condition proceeded with a similar rate as that of seeds treated at 5°C, even though the temperature in the field was higher than 5°C, f.i., the daily mean temperature was 15∼7°C during the vernalization period in one experiment. From the examination of shoot apex development, it was suggested that in the vernalized plants the production of leaf or bract primordium is activated, which in turn leads to the spikelet initiation
