Sample processing of maize genetic resources

Contributors to this page: CIMMYT Maize, Mexico (Suketoshi Taba, Bonnie J. Furman), with inputs also received from IITA, Ibadan, Nigeria (Dominique Dumet); EMBRAPA (maize and sorghum genebank), Brazil (Flavia Teixeira); USDA (ARS/NC7, ISU); USA (Mark Millard).

Seed cleaning
Seed drying
Seed moisture content

Seed cleaning

Cleaning is the removal of foreign material (debris) and low quality, infected and/ or infested seeds from the accession seed lot. The accession seed lot should match the original description in the passport. Pure quality seed should be preserved in the genebank.

Visual inspection of seeds

Visual inspection of the seeds is the most practical approach to ensure seed quality and accession integrity in the genebank. Inspection should be performed at the time of shelling ears, cleaning seeds and packaging seed for storage.

Visual inspection of seeds (photo: CIMMYT)


Special treatments

It is important that regenerated seeds are cleanly stored, without insect damage, during seed processing.

Disposal of contaminated material

It is extremely important to correctly dispose of contaminated material to avoid contamination of the other material stored in active and base collections.

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Seed drying

Seed drying is the most critical genebank operation to insure longevity of the maize seeds as an orthodox seed species. Refer to protocol seed storage behavior rules for seed testing (ISTA 2009) and keeping seeds alive (Probert and Hay 2000) for more information.

1st stage of drying

2nd stage of drying

Recording information during seed cleaning and drying

The following information should be recorded for each processing step:

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Determination of seed moisture content

Seed moisture must be measured to make sure that they have the optimum moisture content for efficient preservation in active and/or base collections. Monitoring the seed moisture content during storage can be done with representative samples from the group of accessions that share the same seed regeneration origin.

Sampling frequency


Method 1

Method 2

Recording information during the determination of seed moisture content

The following information should be recorded for each processing step:

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References and further reading

Chang TT. 1985. Preservation of crop germplasm. Iowa State Journal of Research. Vol. 59. No.4. pp. 365-378.

Ellis RH, Hong TD, Roberts EH. 1985. Handbook of seed technology for genebanks volume I. Principles and Methodology. Handbooks for Genebanks no. 2. International Board for Plant Genetic Resources, Rome.

FAO/IPGRI. 1994. Genebank standards. Food and Agriculture Organization of the United Nations, Rome and International Plant Genetic Resources Institute, Rome. Available in English, Spanish, French and Arabic.

Global Crop Diversity Trust. 2007. Global strategy for the ex situ conservation and utilization of maize germplasm [online]. Available from: Accessed: 4 August 2010.

Hanson J. 1985. Procedures for handling seeds in genebanks. Practical manuals for genebanks no. 1. International Board for Plant Genetic Resources, Rome.

Hong TD, Ellis RH. 1996. A protocol to determine seed storage behavior. IPGRI Technical Bulletin No. 1. International Plant Genetic Resources Institute. Rome. Italy. Available here.

International Seed Testing Association ISTA. [online]. Available from: Date accessed: 30 January 2010.

Mezzalama M, Gilchrist L, McNab A. 2005. Seed Health: Rules and regulations for the safe movement of germplasm. Mexico. D.F., CIMMYT. Available from: Date accessed: 3 September 2010.

Probert RJ, Hay FR. 2000. Keeping seeds alive. In: Black M, Bewley JD, editors. Seed technology and its biological basis. CRC Press LLC. USA and Canada. pp. 375-404.

Taba S, van Ginkel M, Hoisington D, Poland D. 2004a. Wellhausen-Anderson Plant Genetic Resources Center: Operations Manual, 2004. El Batan, Mexico: CIMMYT. Available here.

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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.