Figure 1.5 – Stages in seed cleaning process. (a) inflorescence of San Diego thornmint; (b) large chaff separated from seeds; (c) moderately cleaned seed with large chaff removed. This stage is appropriate for long-term storage. Moderate cleaning can save time so that seeds can be processed quickly, dried, and placed into cold storage; (d) meticulously cleaned seed. This level is appropriate for curation packages that require seed testing.
Figure 1.6 – Silica gel is orange when activated and turns green when deactivated.
Orthodox seeds should be dried quickly so that they will have approximately 12% water content at the intended storage temperature.
The RH % target should be no more than 25% RH (lower risk of failure) and no less than 10% RH (higher risk of failure) at the intended storage temperature.
TABLE 1.1 Recommended drying conditions for seeds stored in moisture-proof containers at various temperatures. The given drying temperature and RH combinations give a storage RH of 20% at the indicated storage temperature.
|Drying Temperature (°C)||Drying Relative Humidity for Storage at 15°C||Drying Relative Humidity for Storage at 5°C||Drying Relative Humidity for Storage at –20°C|
Drying seeds at temperatures less than the storage temperature is not cost-effective and therefore is strongly discouraged.
Note that practitioners should feel comfortable achieving RH targets ± 3% while drying seeds.
Walters (2004, unpublished data 2019)
Anchor Steel Blue Seed Germination Blotter: Anchor Paper Co., (800) 652-9755
Agriculex Column blower (to separate seeds from chaff quite extensively Agriculex), (519) 837-0871
Rennco heat sealer (recommended model is LS-18-120) to seal barrier foil envelopes, rather than using an iron, to ensure a fully sealed package. The optimal temperature is 177o C, according to the engineer who tested the specifications on CPC packaging material. Relatively inexpensive, used heat sealers can be found online.
Wireless (real-time, live)
OmniSense, (843) 522-0350
You will need to purchase a gateway and sensors individually or you may purchase together in the DriFi Restoration Moditoring Kit. There is a US $20 monthly data access fee.
HOBO Temp/RH 2.5% Data Logger (most accurate and longest lasting) Onset, (800) LOGGERS.
Humidity/temperature pen (inexpensive, with a digital display)
Fisher Scientific, (800) 766-7000
Basey, A. C., J. B. Fant, and A. T. Kramer. 2015. Producing native plant materials for restoration: 10 rules to collect and maintain genetic diversity. Native Plants Journal 16: 37–52.
Dickie, J. B., and H. W. Pritchard. 2002. Systematic and evolutionary aspects of desiccation tolerance in seeds. Pages 239–259 in M. Black and W. Pritchard, editors. Desiccation and plant survival. CABI, Wallingford, UK.
Food and Agriculture Organization of the United Nations (FAO) 2014. Genebank standards for plant genetic resources for food and agriculture. Rome, Italy. http://www.fao.org/3/a-i3704e.pdf.
Guerrant, E. O., Jr., K. Havens, and M. Maunder, editors. 2004. Ex situ plant conservation: supporting species survival in the wild. Island Press, Washington, DC.
Hong, T. D., S. H. Linington, and R. H. Ellis. 1998. Compendium of information on seed storage behaviour. Royal Botanic Gardens, Kew, UK.
Millennium Seed Bank Partnership (MSB). 2015. Seed conservation standards for “MSB Partnership Collections.” Royal Botanic Gardens, Kew, UK.
Pérez, H., E., and J. G. Norcini. 2010. A new method of wiregrass (Aristida stricta Michaux) viability testing using an enhanced forceps press test. Natural Areas Journal 30:387–391.
Seed Conservation Hub. Accessed August 3, 2017.
Walters, C. 2004. Guidelines for seed storage. Pages 442–453 in E. O. Guerrant, Jr., K. Havens, and M. Maunder, editors. Ex situ plant conservation: supporting species survival in the wild. Island Press, Washington, DC.
Walters, C., P. Berjak, N. Pammenter, K. Kennedy, and P. Raven. 2013. Preservation of recalcitrant seeds. Science 22: 915–916.
Wieland. G. D. 1995. Guidelines for the management of orthodox seeds. Center for Plant Conservation, St. Louis.
Wyse, S. V., and J. B. Dickie. 2017. Predicting the global incidence of seed desiccation sensitivity. Journal of Ecology. doi: 10.1111/1365-2745.12725.