Test Overview
Duration: Varies by species; typically 7–28 days
A Standard Germination Test, often referred to as a warm germination test, determines the percentage of seeds that produce normal seedlings under favorable, controlled laboratory conditions.
Standard germination testing is used to evaluate seed quality and provides germination information used for seed labeling. The temperature, duration, planting substrate, and other testing conditions are determined by the species and applicable testing rules.
The Iowa State University Seed Laboratory maintains testing procedures for approximately 700 species of seed.
Test Details
A standard test consists of 400 seeds, typically divided into replications. Seeds are planted using the substrate and environmental conditions appropriate for the species being tested.
Depending on the species, seeds may be planted in rolled paper towels, on blotter or crepe cellulose paper, in sand, or using other prescribed substrates.
Testing periods vary considerably by species. For example, corn is typically tested for seven days, while some grasses may require up to 28 days.
Some freshly harvested or dormant seed may receive a prechill treatment before germination testing. During prechill, planted seed is held at a low temperature for a prescribed period to help overcome dormancy before being moved to standard germination conditions.
At the completion of the test, seedlings and ungerminated seeds are evaluated and results are reported as percentages of normal seedlings, abnormal seedlings, dead seeds, and, when applicable, dormant or hard seeds.
Sand Germination
Sand may be used as the germination substrate for certain species or testing situations. Seeds may be planted directly in sand or covered with sand over another planting medium.
Sand provides uniform moisture and may help reduce the effects of some fungi. It can be particularly useful for very dry soybean seed by providing more gradual and uniform water uptake.
Sand germination may be requested as the primary germination test or in addition to a germination test conducted on artificial media. Comparing results from the two methods can provide additional information about seed performance, particularly when fungal pressure or rapid water uptake may be affecting germination.
Sample Requirements
A minimum of 400 seeds are required to conduct an AOSA or ISTA standard germination test.
The recommended amount to submit may be greater than the number of seeds used for the germination test and varies by species.
See How Much Seed Should I Send? for minimum sample-size guidance.
Additional seed is required when other tests are requested on the same sample.