Processing - cleaning and testing the seeds
1. Assessment of likely seed storage characteristics
2. Seed cleaning
3. Visual check on the quality of the collection
4. Seed quantity determination
5. Drying
Checking the label on a package in the drying room
The initial drying room where seeds are placed on arrival
The majority of the world's seed-bearing species produce ‘orthodox’ seed that can be dried and then frozen. Under most circumstances, both drying and freezing increase the longevity of such seed. To maximise seed longevity, most seed banks (including the Millennium Seed Bank) dry the seeds using fairly cool conditions. To do this, the air within the drying facility or room must be chemically dried. Moisture is thus pulled out of the seed into the 'moisture-hungry' air (15-18°C and 15% relative humidity). The MSB has two drying rooms – one for receiving the collections on arrival prior to cleaning and one, located next to the cold rooms in the seed vault, for the final drying prior to storage. Alternative means of drying seed are also being investigated by the project.
Eventually, during drying, equilibrium is achieved with no net movement of moisture either into or out of the seed (usually this takes less than a month). When equilibrium has been achieved, the seed is checked for dryness by non-destructive means using an hygrometer. Once dried, the collections are packaged in a variety of different container types prior to sub-zero storage.
6. Packaging
