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The Tetrazolium test

Stained barleyTetrazolium salt stains all living tissue in the seed embryo red, thus enabling trained analysts to determine the seeds viability or otherwise. The tetrazolium test is used to give a quick  estimate of germination potential.  The result of a tetrazolium test will generally predict the germination test result closely, however the tetrazolium test will not detect certain types of abnormalities nor will it give any indication of disease levels, chemical damage or dormancy.

The tetrazolium test should be used when seeds have to be sown shortly after harvest or to detect the presence of sprouting and various types of harvesting and/or processing damage (heat damage, mechanical damage, insect damage). The tetrazolium test is not suitable for carry over seed.

The following are the species for which our lab offers the tetrazolium test:

  • Barley
  • Wheat
  • Oat
  • Rye
  • Triticale
  • For tree seeds, please contact the laboratory on 01 6157521

Test times

For cereals the test time is one working day from the initiation of the test. Delays in processing may arise during peak times 

Standards

There are no prescribed standards for tetrazolium tests and seed cannot be certified on the basis of a tetrazolium test alone. It is generally recommended that in order to be confident of achieving a germination standard of 85% in barley, wheat & oats the tetrazolium test should achieve a result of  94% or above. This is provided that a suitable fungicide is used to control seed born diseases and that there is no chemical damage present on the seed.

Tetrazolium test reports

The tetrazolium test report states the number of seeds found to be viable. In addition, where present, the report will state separately the number of heat damaged seeds and sprouted seeds.

For example viable seeds = 90%, 2% heat damage 2% sprouted. This means that 90% of seeds were found to be viable and of the remaining 10% of non-viable seeds 2% were non-viable as a result of heat damage and 2% were not viable as a result of sprouting.