Recent Advances of Carnation Production in Japan
The present status of technological improvements and problems in carnation production in Japan is reviewed. One of the urgent issues in breeding program in Japan is to find out cultivars resistant to a soil-borne bacterial wilt disease, which is difficult to control in cultural practices. Some wilt-free and very resistant species are identified in dianthus species. They are presently utilized in a breeding program. High temperature generally causes carnation plants to accelerate respiration and reduce photosynthesis. With the purpose of making full use of solar radiation, a mulching technique with aluminized reflective film was developed. It is now widely adopted in Japan because of its effectiveness in obtaining high yields of cut flowers. Stems of cut flowers grown under a high temperature easily droop and their market values are lost. A foliar spray treatment with a plant growth regulator, called ethychlozate, immediately before the first blooming stage was effective in improving carnation stem quality. It was confirmed that use of silver thio-sulfate was recommendable. This treatment is widely employed in Japan. Other two methods art reviewed: one is a technique of transplanting at a high density followed by thinning to an ordinary density at the first blooming stage, and the other is a bud cut technique, thereby the flowers harvested at the stage of tight green buds are stored under a low temperature and flowered artificially by soaking the base of cut flowers in an opening solution.