Effect of night-break-lighting at different times on summer-to-autumn-flowering small-flowered spray-type chrysanthemum
2019
Murazaki, S. (Horticultural Institute, Ibaraki Agricultural Center, Kasama, Ibaraki (Japan)) | Suzuki, K.
The conventional timing of night-break-lighting to inhibit flower induction has been at midnight in Chrysanthemum morifolium. In this study, we investigated the light-sensitive time zone of summer-to-autumn-flowering small-flowered spray-type Chrysanthemum, to establish an effective and practical light culture system. The time zones of night-break-lighting were midnight (10:00 pm-2:00 am; the conventional method), an earlier time zone (8:00 pm-12:00 am), and a late time zone (12:00 am-4:00 am). Several cultivars of the August-flowering type by light culture were used for the experiments. Plants were grown in open fields, and an incandescent lamp and a fluorescent lamp were used as light sources. As a result, the most light-sensitive time zone was the late time zone, because it effectively inhibited flower bud initiation. Long-day leaf numbers and number of days to flowering were increased by night-break-lighting in the late time zone. Moreover, the night-break-lighting in the late time zone was the most practical method, since we demonstrated effectively inhibited flower bud initiation in farmers' fields. For the above reasons, night-break-lighting in the late time zone outperforms the conventional method for the regulation of flowering.
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