Deep physiological dormancy in desiccation-sensitive seeds of Osmanthus fragrans (Oleaceae)

To assess seed dormancy and desiccation tolerance in sweet osmanthus, we exposed seeds to various treatments. Freshly-harvested mature seeds exhibited a dormant trait. Partial drying from a moisture content of 45.1% f.w. to 40% did not significantly affect the final germination, but further desiccation was detrimental. Pretreatments including GA₃, warm stratification and removing the episperm did not facilitate dormancy release. However, after four months at 4°C, the undried seeds germinated, suggesting that the seeds have deep physiological dormancy (PD). Increasing the chilling period from 16 to 20 weeks increased germinability and sensitivity to desiccation, but 30 weeks chilling was deleterious to seed quality. After becoming non-dormant, 30 / 20°C (12-hour photoperiod) was the optimum temperature for germination, followed by 25 / 15°C and 23°C. Changing environments and seed dormancy and sensitivity to desiccation may impact the regeneration of this species in the wild.