ISHS Acta Horticulturae 125: Symposium on Chrysanthemum
THE RESPONSES TO PHOTOPERIOD AND TEMPERATURE IN JAPANESE JULY TO SEPTEMBER FLOWERING CHRYSANTHEMUMS |
| Authors: | J. Kawata, T. Toyoda |
| Abstract:
In order to be able to control flowering time, the responses to photoperiod and temperature have been investigated in Japanese July to September flowering chrysanthemums. Some of the July flowering cultivars were quantitative short-day plants, most of the others were qualitative short-day plants and a few were day-neutral plants. Most of the August and September flowering cultivars were qualitative short-day plants at high temperature in summer as were the autumn flowering cultivars. The later the flowering time in natural long days, the larger the difference in the number of days to anthesis in natural long days and in short days. The reaction period of the July to September flowering cultivars in short days ranged from 7 to 12 weeks. It is estimated from the weekly changes in the number of days from the start of short days to the visible bud stage and to anthesis that the later the natural flowering time, the higher the optimum temperature for flower bud initiation and development. The results shows that some of the July to September flowering cultivars could be incorporated in all-year-round schedules, especially for summer growing in low latitude region in Japan with lighting only or short periods and short hours of blacking-out compared with those necessary for autumn flowering cultivars. | |
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