When Should I Use This Test?
The Cold test is a stress test which simulates the cold, wet conditions
of planting season and is an indicator of seed vigor.
High Vigor: strong seed will germinate, emerge and grow well.
Low Vigor: weaker seed will not germinate or will have a slower germination and growth in response to the stress. This test is used for corn and soybeans.
What Technique is Used?
Shoebox Method: 1" of vermiculite is placed above and below seed layer (corn test also adds 3 oz. layer of field soil to the seed layer), water is added to each box to 75% saturation, then covered with lid. One test = 2 boxes of 100 seeds/box. The boxes are stored in the cold room at 10ºC (50ºF) for 7 days. Test is then moved to warm germinator at 23ºC (73ºF) for 5 days. Seedlings are evaluated on day 12.
What Do the Results Mean?
Results are reported as a percentage, which represents the number of seedlings categorized as "normal" out of the 200 seed test. Technicians record the number of normal, abnormal and dead seedlings.
A good cold test score is 85% or higher. A seed lot that scores less than 85% is considered marginal. Cold test scores are used to evaluate the seed lot, the lower the score, the less vigorous the seed.