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.
Among the ex situ methods for the preservation of forest tree germplasm, conventional seed banking is considered the most efficient method for the majority of species whilst cryopreservation has an important role in long-term conservation. The influence of cryoprotectants prior to liquid nitrogen (LN) storage and osmoconditioning priming treatments with polyethylene glycol (PEG) after LN storage were evaluated for germination (%), germination value (GV) and mean germination time (MGT) in seeds of Cryptomeria japonica. Sugi seeds were treated with two cryoprotectants (DMSO and PVS2) before immersion into LN and stored for three days. Although the C. japonica seeds survived liquid nitrogen treatment, their viability was reduced from 25 % of intact seeds to 17 % in LN. The seeds treated with 35 % DMSO showed higher germination (28 %) as compared with seeds directly-immersed in LN without cryoprotectant treatment. In contrast, PVS2 pretreated seeds decreased germination (13 %). Two concentrations of PEG priming treatments were carried out. Osmoconditioning treatment in -0.4 MPa PEG solution after removal from LN enhanced the subsequent germination percentage and decreased MGT. PEG treatments at both -0.4 and -1.2MPa to PVS2 pretreated seeds before cryopreservation partially alleviated the negative effect of PVS2. DMSO pretreated seeds immersed into LN and treated with -0.4MPa PEG maintained the 28 % of germination obtained in the control conditions and reduced the mean germination time (MGT). It can therefore be summarized that pretreatment with 35 % DMSO was suitable for the cryopreservation of C. japonica seeds whilst the PEG priming treatment circumvented imbibitional damage after LN exposure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.