LEDs are likely to be the most effective replacement for tungsten bulbs used for day-extension and night-break lighting, researchers have concluded.
Studies were carried out at the University of Warwick as part of Horticultural Development Company (HDC)-funded project PC 296. These showed that LEDs were as effective as tungsten bulbs if the appropriate combination of red and far-red light, at the extreme end of the spectrum, was used.
Tungsten bulbs, which have been used traditionally by growers, are being phased out by Defra because they are inefficient.
Speaking at the HDC Poinsettia Group meeting last week, Warwick research leader Steve Jackson said: "It would be good now to find the appropriate combination of red and far-red light that needs to be used."
Tim Haworth of CambridgeHOK, the UK partner of Phillips LED Horticulture, which supplied the LEDs, added: "We are hoping to get close to the right recipes, but we have a long way to go. We have to work out how plants work."
The project, now in its second year, has shown that far-red light needs to be present for long-day plants such as antirrhinum and pansy, and a combination of red and far-red LEDs can be more effective than tungsten lighting.
For short-day plants such as Christmas cactus and poinsettia, day extension treatments need to contain far-red light, and red light is most effective for night-break treatments.
STUDY PLANTS TESTED
- Christmas cactus
- Lisianthus (Eustoma)