Viability Testing of Germplasm

View section on seed viability testing by clicking on the icon above (0.7 MB)

Page compiled by: Bioversity International/ILRI, Addis Ababa, Ethiopia (Alexandra Jorge); ILRI, Addis Ababa, Ethiopia (Jean Hanson) including information extracted from: Rao NK, Hanson J, Dulloo ME, Ghosh K, Nowel D and Larinde M. 2006. Manual of seed handling in genebanks. Handbooks for Genebanks No. 8. Bioversity International, Rome, Italy. 147pp.

What is viability testing

Seed or plant viability is the measure of how many seeds or how much plant material in a lot are alive and could develop into plants that will reproduce under appropriate field conditions.

Why should viability be determined

Testing seed viability (photo: ILRI)

It is very important that seeds or plant material stored in the genebank are capable of producing plants when sown in the field. They must have high viability at the start of storage and maintain it during storage. Seeds or plant material with a high initial viability will also survive longer in storage. Seed or plant viability declines slowly at first and then rapidly as the seeds or plant material age. It is important to know when this decline occurs in order to take action to regenerate the accession. Excessive deterioration will lead to loss of material.

When should viability be determined

Seed material

Viability testing is crucial for the monitoring of seed conservation. It can take from a few days to weeks, depending on the species. If possible, the results of viability tests should be made available before seeds or plant material are packaged and placed in the genebank so that poor quality seeds can be identified and regenerated.

While awaiting the results of viability tests, or if there is a delay in conducting the viability tests before storage, seeds should be placed in a cool environment to minimize their deterioration.

Tissue culture plant material

Cryo plant material

How should viability be determined

The determination of viability depends on the species and method of conservation.

Seed material

Plant material (tissue culture and cryopreservation)

The germination test (applicable for seeds)

Testing germination in sand (photo: ILRI)

Testing germination on filter paper (in tray)(photo: ILRI)

What is a germination test

A germination test is performed to determine what proportion of seeds in an accession will germinate under favourable conditions and produce seedlings judged as normal according to specific criteria for each species [see Association of Seed Analysts (AOSA), 2005; ISTA, 2005]. This is because the aim of seed testing is to give an indication of how the seeds will perform as propagules in the field.

When are seedling defects classified as abnormal?

How is germination tested

Basic requirements for seed germination are: water, oxygen, light and suitable temperature. Seeds of different species have different requirements and no general set of conditions can be relied upon to germinate seeds of all species. Seeds of some species are more tolerant and germinate in a wide range of conditions but complete germination can only be achieved under optimum conditions. Seed dormancy is seen when seeds imbibe water under suitable temperature and light for germination but germination does not occur.

How many seeds should be tested

References and further reading

AOSA (Association of Official Seed Analysts) 2005. Page 113 in: Rules for Testing Seeds (Capashew Ed.), 4-0, 4-11. Las Cruces, NM.

FAO. 2013. Genebank standards for plant genetic resources for food and agriculture. Food and Agriculture Organization of the United Nations, Rome. Available in English, Spanish, French, Arabic, Russian and Chinese here.

ISTA. 2008. International Rules for Seed Testing. International Seed Testing Association. ISTA secretariat, CH-Switzerland. Available from:

Rao NK, Hanson J, Dulloo ME, Ghosh K, Nowel D, Larinde M. 2006. Manual of seed handling in genebanks. Handbooks for Genebanks No. 8. Bioversity International, Rome, Italy. Available in English (1.5 MB),  Spanish (1.4 MB) and French (1.9 MB).

Thormann I, Metz T, Engels JMM. 2004. The Species Compendium (release 1.0; December 2004). [online] Available from: Date accessed 09 April 2013.

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The Genebanks

The 11 CGIAR genebanks currently conserve 730,000 of cereals and grain legumes, forage crops, tree species, root and tuber crops, bananas and crop wild relatives.