Test Overview
Duration: 2 days
The Tetrazolium (TZ) Test is a rapid biochemical test used to determine seed viability. It can provide an estimate of the percentage of living seed in a sample more quickly than a standard germination test.
Unlike a germination test, which evaluates a seed's ability to produce a normal seedling, TZ evaluates the condition of living tissues within the seed. For this reason, TZ results and standard germination results may not always be the same.
TZ testing is particularly useful for species that exhibit high levels of seed dormancy, including many native species. Because viable dormant seeds may not germinate during a standard germination test, TZ can provide additional information about the overall viability of the seed lot.
TZ may also be used to evaluate ungerminated seeds remaining at the end of a germination test to help determine whether those seeds are dead or viable, but dormant.
Test Details
Seeds are first conditioned by allowing them to absorb water. Depending on the species, seeds are then cut, pierced, or otherwise prepared to expose tissues to a tetrazolium solution.
Living tissues react with the solution and develop a red stain. The location and intensity of staining are evaluated to determine whether the essential structures of the seed are viable.
In addition to determining viability, staining patterns can provide useful diagnostic information about the condition of a seed lot. TZ testing may be used to help identify frost injury, mechanical damage, deterioration, and other causes of reduced seed quality.
For some species and applications, TZ may also be used to evaluate seed vigor.
Sample Requirements
A minimum of 200 seeds are required for a stand-alone TZ test. Please submit additional seed when possible to allow for sample preparation or additional testing.
When TZ is requested as a follow-up to a germination test, the ungerminated seed from the germination test are evaluated directly.