Growing chrysanthemum all year round in Japan is accomplished by two different methods. One method is the application of either short day treat-ment or long day treatment to Autumn flowering chrysanthemum. This group of chrysanthemum is responsible to short day treatment in both stage of flower bud initiation and flower bud development. This is similar to both American and European methods of culture. The other method is the utilization of various types of chrysanthemums which have different blooming time hereditarily. In this case either short day treatment or long day treatment is seldom required.
Many varietis of August and September flowering chrysanthemums, as well as Summer and Winter flowering chrysanthemums which usually bloom from May to July, and from December to January respectively, are used for this purpose. August and September flowering chrysanthemums have been bred recently, while Summer and Winter flowering chrysanthemums have existed for many years.
In this experiment, the responses of flower bud initiation and flower bud development to photo-periodism and temperature were examined, and ecological classification of chrysanthemums were attempted.
The classification were made as follows:
