Seed storage, germination and seedling emergence in Rhamnus catharticus

Abstract

This study was aimed to improve the understanding of germination ecology and to explain the invasive character of the common buckthorn (Rhamnus catharticus) in North America. Its fully mature seeds are characterized by a lack of dormancy. In laboratory conditions, favourable thermal conditions were identified for seed storage, germination and seedling emergence. At the cyclically alternating temperature of 20-30°C (16+8 h daily), seeds of this species showed a high germination rate within few weeks. Two other thermal variants, 3-15°C and 3-20°C (16+8 h daily), were much less effective for seed germination. However, cold stratification (at 3°C) in a moist mixture of peat and sand, lasting 4-8 weeks, caused a remarkable increase in germination rate also at 3-15°C. Seeds extracted from ripe fruits and dried (to a moisture content of about 10%) showed high germination and emergence rates after storage for 3.5 years at -3°C.