Seed Germination of Arbutus unedo, A. andrachne and Their Natural Hybrid A. andrachnoides in Relation to Temperature and Period of Storage

Abstract

Arbutus unedo L., A. andrachne L., and their natural hybrid, A. ×andrachnoides Link, are the three Arbutus species of the Eastern Mediterranean Macchia. A. unedo is used as an ornamental plant and as cut foliage, whereas the other two species have the potential to be introduced to the floricultural industry. This study was carried out to clarify whether the seeds of these Arbutus species possess dormancy to determine the temperature range for their germination and the effects of storage period on germination. Seeds of the three species, which were stored dry at 25 °C for either three or 11 months, germinated at very high percentages (82% to 99%) and in a short period of time (24 to 46 days) when incubated at 15 or 10 °C without any pretreatment proving that they do not possess dormancy; germination was faster at 15 °C. At 20 °C only seeds of A. unedo and A. andrachne stored for three months germinated (29% to 34%), whereas at 25 °C, there was practically no germination. Seeds stored for three months germinated (61% to 75%) when incubated at 5 °C, but the germination was delayed and the seedlings did not grow further than the appearance of the radicle unless transferred at a higher temperature (10 to 25 °C). After 27 months of dry storage at 25 °C, seeds did not germinate when incubated at the range of 10 to 25 °C even after pretreatment with cold stratification.