Abstract
Two varieties of winter wheats and one variety of spring wheats were used for materials in these experiments. The plants were grown in winter both in the field under the condition of natural low temperature, and in a greenhouse kept at relatively high temperature. In this way, the plants in various states of vernalization were obtained. Excised stem tips of those plants were cultured in vitro for more than two months under the condition of high temperature combined with continuous illumination by artificial light sources, which might be considered not to affect the progress of vernalization and to be rather favorable for the spike formation in the plantlets in the culture. From the results of these cultures, it was found that the excised stem tips of vernalized plants developed into plantlets on which spikes were formed, while those of unvernalized plants grew up to plantlets only remaining in a vegetative stage. So it was necessarily concluded that the vernalized condition in wheat plants is retained in their excised stem tips, the fact probably showing that some qualitative changes take place in the apical meristem in the course of vernalization.
