In vitro propagation and rooting of Helleborus orientalis in response to LED lighting

Helleborus is an early spring flowering perennial with increasing horticultural importance. To explore these advantages an efficient in vitro propagation system for Helleborus is crucial. In the past, the main goals of in vitro lighting were to sustain photosynthesis and to regulate the photoperiod. Nowadays, the development of LED technology opens the door to a plethora of applications. Therefore, we investigated the effect of light quality (more specific red, blue, red + blue and white LED and white TL light) on the propagation and rooting of Helleborus orientalis. We found that the light spectrum had no effect on the propagation rate as such, but that it influenced the plant morphology (plant height, number of leaves per plant, leaf length, % dry matter). Also rooting was influenced. Red and white LED lights as well as control TL lamps resulted in a significantly longer root compared to the blue and red + blue LED lighting. However, the red LED lighting resulted in the highest number of roots.