ISHS Acta Horticulturae 683: V International Symposium on New Floricultural Crops
FLOWERING BEHAVIOUR OF HELICHRYSUM OBCONICUM DC. |
| Author: | M.J. Oliveira Dragovic |
| Keywords: | Madeira, endemic, ornamental, photoperiod, temperature |
| Abstract:
Helichrysum obconicum is an endemic plant of Madeira Island (Portugal) that has already shown potential to be used as ornamental plant. It is a small shrub with grey silver leaves and small yellow golden flowers. The mechanisms involved in the flowering of this species are not well known. Under natural conditions, plants of H. obconicum start to flower in July-August, and the reproductive period extends until October-November. In January 2000, plants were subjected to the same temperatures (night temperature of 17ºC and 23ºC as day temperature) occurring in nature during the reproductive period and to a photoperiod of 16 hours of light/8 hours of dark. After 3 months they started to flower, while those under natural conditions stayed in vegetative stage and only started to flower in July 2000. A second experiment was conducted to understand if the flowering induction was due to the day length. At the end of March 2001, 122 plants were submitted to natural day length (control) and 122 plants to continuous long days (16 hours of light per day), both of them under the same temperature regime (13.8-28.7ºC). Plants under permanent long day conditions started to flower after 2 months and maintained the reproductive stage until the end of the experiment (March, 2003). The control plants started to flower in July 2001 and the reproductive period ended by December 2001. In the following year, the reproductive period was observed from June 2002 to December 2002. The results obtained from the above experiments lead us to the conclusion that Helichrysum obconicum is a long day plant. | |
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