Sample processing in seed banks of cultivated rice genetic resources

Contributors to this page: T.T. Chang Genetic Resources Centre-IRRI, Los Baños, Philippines (Ruaraidh Sackville Hamilton, Ken McNally, Flora de Guzman, Renato Reaño, Soccie Almazan, Adelaida Alcantara, Elizabeth Naredo); WARDA, Cotonou, Benin (Ines Sánchez); UPLB-University of the Philippines at Los Baños (Teresita Borromeo).

Seed cleaning
Seed drying
Seed moisture content


Cleaning is the removal of physical contamination from the plant material after harvest, before it can be stored. The exposure to unfavourable conditions should be minimized for greater seed longevity in storage.

Visual inspection of seeds

IRRI staff selecting good seeds for storage to the IRRI Genebank facility (photo: IRRI)

For Base Collection

For Active Collection

Bulk sample for active collection

For black-box safety backup storage

For temporary storage to repeat regeneration of harvests with insufficient seeds (<30 g) or inadequate initial germination rate (< 85%):

Special treatments

Disposal of contaminated material

Inspection and certification (purity analysis of seeds)


Certain changes in seed phenotype may occur even though the seeds remain genetically true-to-type:

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Seed drying


1st stage of drying (during seed cleaning)

2nd stage of drying (after seed cleaning)

Alternative drying

Dissecators with silica gel
(photos: Bioversity International/ILRI, by kind permission of RDA genebank, National Agrobiodiversity Center, Suwon, Republic of Korea)

Drying time

Moisture content before drying

Moisture content for storage

Critical moisture content

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

Using a moisture meter to check the moisture content of seeds (photo: IRRI)


The recommended method follows ISTA rules.

Sampling frequency

Before storage

During storage

Before germplasm movement

Sample size


Oven drying

Recording information during determination of seed moisture content

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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.