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TZ (Tetrazolium) Test

The TZ test is a biochemical test which quickly assesses the viability of seeds without having to actually grow them. The seeds are evaluated based on a visual examination of the staining of the embryo and other parts of the seed.

The seeds are first exposed to moisture and allowed to fully imbibe (absorb water). They are then cut or pierced and placed into the clear, colorless tetrazolium solution.  Any living, respiring tissues in the seeds will react with the TZ and turn from white or pale yellow to a deep red color. Unstained areas indicate non-respiring, dead tissue. A visual examination of the staining pattern allows for viability analysis.

Because there is no growing period, results are available quickly, usually within 24 to 48 hours. However, the actual lab time required to conduct a TZ test is considerably more than for a germination test.  Please notify us in advance to ensure prompt TZ test results.

The TZ test is a reliable way to quickly estimate total viability of a seed lot, or for determining dormancy of after a germination test.  It does not, however, take the place of a germination test.  Most states require a standard germination test for labeling seed lots.