THE PHASIC DEVELOPMENT OF CHRYSANTHEMUM AS A BASIS FOR THE REGULATION OF VEGETATIVE GROWTH AND FLOWERING IN JAPAN

The factors controlling the growth and flowering in Japanese summer flowering chrysanthemums are temperature and daylength.
The cuttings from winter suckers cannot initiate flower buds in their early stage of growth even if they are grown under short days and suitable temperature for flower initiation.
After they grow for some duration in a heated glasshouse they become photosensitive.
Their critical day-length for flowering is longer than that of autumn flowering chrysanthemums.

From the above mentioned phenomena and observation on the growth and flowering patterns of chrysanthemums, the following phases in the development of chrysanthemums can be postulated: rosette phase, juvenile phase, photoperiod-sensitive phase and ripening phase.
To pass the first three phases, chrysanthemums require low temperature, high temperature and short days respectively.
The relations between Japanese chrysanthemum growing systems for year-round production and the phasic development are discussed.

Working-party on Greenhouse Chrysanthemum

J. Kawata

https://doi.org/10.17660/ActaHortic.1987.197.14