Effects of temperature, light and pre-chilling on germination of Rhamnus persicifolia, an endemic tree species of Sardinia (Italy)

Abstract

Rhamnus persicifolia is an endemic small tree or shrub belonging to the R. cathartica group. It grows along mountainous waterways of the Central-Eastern Sardinia (Italy). The purpose of this study was to report the effects of temperature, light and pre-chilling on germination of R. persicifolia seeds. The applied treatments included a range of constant temperatures (5-30°C) and two alternating temperature regimes (15/5 and 25/10°C), with two photoperiods (8 h light / day and darkness). In addition, the most effective germination temperature (25°C) was repeated including a pre-chilling period (5°C for 3 months). R. persicifolia reached maximum germination percentages (> 70%) at warm temperatures (≥ 20°C), with no differences between constant and alternating regimes and no response to light. While the pre-chilling period did not increase germination percentage it had a positive effect on germination rate, reducing T50 by more than 50%. These studies provide new information on the seed biology of this endemic species and enable ex situ seed germination, which may prove useful for habitat restoration activities.