Extended Low Temperature and Cryostorage Longevity of Salix Seeds with Desiccation Control

Salix xerophila, S. maximowiczii, and S. koreensis are species of willow native to Korea that are important for bioenergy production. However, the native range of these species has narrowed in recent years due to the impact of climate change. Seeds of these Salix species lose viability within 4 weeks at ambient temperature, and within 4 months at -4°C. Preservation techniques are urgently needed to protect these valuable resources. The effects of seed water content (SWC; 3%, 6%, 9%, 12%, 18%, and 24%) and temperature (ambient, 4°C, -18°C, -80°C, and -196°C) on storage stability were investigated for up to 48, 52, or 60 months, depending on species. Optimal storage temperature and SWC varied between species. S. xerophila seed could be stored without deterioration for 60 months with 9% SWC at -80°C, but rapidly lost viability when stored at -18°C. In S. maximowiczii and S. koreensis, 100% and 90% of normal germination, respectively, was maintained with 18% SWC at -18°C or -80°C. Thus, for some Salix species, storage at -18 and -80°C may provide an economical alternative to cryopreservation or medium-term storage for the maintenance of seedbanks or breeding stocks.