Light sensitivity and germination of Eucalyptus globulus seeds

This study investigated the relationship between light and germination behaviour of E. globulus seeds under laboratory conditions. Although differences in light response were observed between seedlots, germination was consistently faster and more uniform in constant darkness compared with constant light or alternating light and dark conditions. A dark entrainable response to light was observed in which longer periods of darkness from imbibition of between 6 and 30 hours duration increased suppression of germination by subsequent light exposure. The timing of this response was such that germination could be influenced by time of imbibition relative to a 12 hours/12 hours light/dark diurnal cycle. These observations indicate that careful management of light conditions during the early stages of germination may be important to minimise variability in germination and seedling size in commercial E. globulus nurseries.