Seed testing

Moisture content

The moisture content of cleaned seed is determined before storage. Two replicates of up to 2 grams each are put into aluminum containers and placed in a convection oven at 103°C for 16 hours. Percent moisture content, on a fresh weight basis, is then calculated.

The target moisture content for most seed is 5–8%. Seed that is above this range is further dried before being stored.

Seed weight

Seed weight (based on 1000-seed) is determined by counting and weighing eight replications of 100 seeds, calculating the average and then multiplying that average by 10. This information is helpful for estimating the number of seeds in a weighed sample, and for identifying variation in seed size within a species.

Germination tests

Germination tests are conducted to determine seed health and viability. Tests are conducted before storage and then periodically afterwards (usually every 5–10 years) to monitor changes in viability.

Petawawa Germination Boxes and the germination medium Versa-Pak™ are used for these tests. For conifer species, 4 replications of 50 seeds are placed on the Versa-Pak™. For testing larger hardwood seeds, the number of seeds is reduced. The germination boxes are placed in a controlled environment germination cabinet, undergoing a pre-determined germination regime such as 8 hours of light at 30°C and 16 hours of darkness at 20°C, with a constant relative humidity of 85%.