Assessing the storage potential of seed collections to inform the management of wild species seed banks

Context The storage of seed in seed banks is a primary strategy for the ex-situ conservation of plant species globally. However, changing practices have meant that institutions storing seeds for decades have often stored older collections sub-optimally for at least some of the storage time. Aims Using banked seed collections at Kings Park and Botanic Garden (Perth, Western Australia), we aimed to assess the relative future longevity of several seed lots within 10 species. These seed lots had been stored for 4–34 years. Methods We conducted germination assessments on seeds from 44 collections. We conducted a rapid ageing experiment for species with multiple accessions that retained high viability by subjecting seeds to 60% relative humidity at 45°C to determine the potential remaining longevity. Key results Several collections of Brachyscome iberidifolia, Myriocephalus gueriniae, Olearia axillaris and O. pimeleoides banked in the 1980s and 1990s displayed 0% germination. Newer collections of B. iberidifolia, Hyalosperma cotula, O. axillaris, Panaetia lessonii, Podotheca angustifolia and Trachymene pilosa retained similarly high, consistent viability over time in storage. Rapid ageing of these collections showed that the time to 50% loss of viability (p50) varied significantly and was not necessarily lowest for the oldest seed collections. Conclusions Rapidly ageing seeds enabled us to determine that several species and individual collections have lower longevity and therefore need to be prioritised for more frequent viability monitoring, use, or recollection. Implications This method could be used in wild species seed banks globally for making more informed decisions about historical and ageing seed collections.