Seed testing

For commercially sold seed, all four of these tests are done in dedicated laboratories by trained and usually certified analysts.

They may be pre-moistened, in which case the seeds are allowed to imbibe water between a moistened germination paper blotter.

Seeds are then dissected, either longitudinally or transversely, with a scalpel so that the embryo is exposed to the tetrazolium chloride solution.

Dehydrogenase enzymes present in living tissue reduce the tetrazolium chloride to formazan, a reddish, water-insoluble compound.

This reaction occurs in or near living cells, which are releasing hydrogen in respiration processes.

Sound tissues produce a normal red color and resist the penetration of tetrazolium.

Regardless of how they are reported, TZ test results for viability give you an estimate of the maximum percentage of seeds that have the potential to produce normal seedlings.