March 8, 2008 in Uncategorized
Seed germination rates are given based on warm germination tests where the seeds are germinated at 77 F. However, sometimes a seed lot will have a good warm germination test (high percentage) but perform poorly in the field. This may be due to poor germination and vigor in cold conditions. A cold germination test can be performed on seed to test for these effects. The following are descriptions of these tests from the Iowa State University Seed Testing Laboratory.
Cold Germination: “The Iowa Cold Test”
Duration: Typically 12-14 days.The cold germination test gives a reasonable idea of emergence under less than ideal conditions. Two replications of 100 seed are placed on Kimpak® (special paper) that has been moistened and chilled overnight at 10C (50 F). The seeds are covered with a non-sterile sand/soil mixture and returned to 10C (50 F) for seven days without light. The cart is then moved to 25C (77 F) for five to seven additional days. Seedlings that emerge through the sand/soil mixture are evaluated according to AOSA Rules. An extended cold test is also available which exposes seed to two weeks in the cold instead of one.
Saturated Cold Germination
Duration: Typically 9 or 10 days. The saturated cold germination test is another way of determining how well a seed lot will do under unfavorable conditions. Some consider it to be a more severe test than the tray method. Seeds are placed on a thin layer of saturated soil on paper towels over a special tray. Seeds are turned so that the side of the corn kernel closest to the embryo is down against the soil. The cart is placed in 10°C (50 F) for seven days without light and then moved to 25°C (77 F) for two to three more days. The number of normal seedlings, abnormal seedlings, and dead seed are recorded.
Contact the Delaware Department of Agriculture Seed Laboratory for more information on cold germination tests for seeds. (302) 698-4500 http://dda.delaware.gov/plantind/seedtest.shtml
Information from the Iowa State University Seed Testing Laboratory http://www.seeds.iastate.edu/seedtest/test/index.html