Germplasm preservation is an important program in the United States and throughout the world.
In 1974, the International Board for Plant Genetic Resources was established to provide an international network of gene banks to conserve genetic resources.
The major facility in the United States for germplasm conservation is the National Seed Storage Lab in Colorado.
Seeds are stored on movable shelves in special containers under controlled environmental conditions.
The National Seed Storage Lab primarily stores economically important food crops as seeds. The storage facility is temperature and humidity controlled to maintain a suitable environment for seed longevity.
Each accession is carefully stored with bar code identification and its information logged in a large computer data base. Descriptive material is recorded for each new accession on the Germplasm Resources Information Network. Seed samples are tested for viability, dried to approximately 6 percent moisture and stored at -18°C.
Seed lot sizes vary for storage from between 3,000 and 4,000 seeds from cross-pollinated species and 1,500 to 3,000 seeds for pure lines.
Seed lots are tested every five or ten years for germination. Those showing low viability are re-grown and a new seed crop stored for that accession.
Seeds can be made available to breeders and researchers on request.
A portion of the seeds in the National Seed Storage Lab are stored in ultra-low conditions.
These seeds are cryopreserved by immersion and storage in liquid nitrogen at -196°C.
Under these conditions, it is expected that seeds will survive for longer periods of time compared to conventional storage.