Crop Genebank Knowledge Base

Articles

Storage of radish genetic resources

Contributors to this page: CAAS, China (Qiu Yang, Li Xixiang); Bioversity International, Italy (Imke Thormann, Ehsan Dulloo); CGN, Netherlands (Noortje Bas); IPK, Germany (Andreas Börner, Ulrike Lohwasser); AVRDC, Taiwan (Andreas Ebert); USDA, USA (Larry Robertson); NBPGR, India (Chitra Pandey); SASA, UK (George Campbell); University of Warwick, UK (Charlotte Allender).

Contents:
Base collection
Active collection

Base collection

NGB-NBPGR inside view of long-term storage (photo: NBPGR)

Sample specifications

Minimum sample size for storage

The minimum sample size for storage should at least include sufficient seed for three regeneration cycles and four germination tests.
It is useful to prepare for each accession when packaging, a number of user samples (depending on the expected frequency of distribution of the accession), which are ready for distribution in case of request from the active collection, sufficient bags with germination test samples, regeneration samples, and one or two duplicate samples for safety duplication.
The minimum samples size should be 1000-2000 seeds
Examples of sample sizes for base collection storage.
- AVRDC: 1100 seeds. This includes 4 bags with germination testing samples.
- CAAS: 6000 seeds.
- CGN: 2600 seeds split in three bags with 600 seeds each for regeneration and 4 bags with 200 seeds each for germination testing.
- IPK: 1000 – 2500 seeds (this is for two regeneration cycles; germination tests are done from the active collection)
- NGB-NBPGR: 4000 seeds, single packet.
- USDA: 2000 seed
- WARGRU: 10g

Minimum viability for storage

The initial viability of the accessions is preferred to be more than 85% and it should not be less than 80% for cultivated material and 60% for wild relatives.

Moisture content

3-7%. (FAO/IPGRI 1994)

Container specifications

Seed packaging method

Packing is best carried out in an air-conditioned room with controlled humidity (<=20% RH) as quick as possible after drying.
Exposure time of seeds to humidity – even if controlled – should be kept to a minimum.
Self adhesive water proof labels should be pasted on the outside of each packet.
The information on the external label should be duplicated on a label maintained inside the seed packet.
Labels should have the information on
- Genus and species name
- Accession Number
- Collector Number
- Moisture Percentage
- Germination Percentage
- Seed number
- Date of storage
- Donor Institute
The most frequently used method are aluminum foil packets sealed hermetically with a heat sealer. Vacuum should be used with caution as it can damage seeds.
It is useful to prepare for each accession when packaging, a number of user samples (depending on the expected frequency of distribution of the accession), which are ready for distribution in case of request from the active collection, sufficient bags with germination test samples, regeneration samples, and one or two duplicate samples for safety duplication.

Specifications of packaging material

Three layered standard aluminum foil packets consisting of following layers:
- Polyester 17g/m²(12μm) (outer)
- Alufoil 33g/m² (12μm) (middle)
- Polyethylene 63g/m² (80μm) (inner)
Rust-proof aluminum boxes with a screw-off caps and rubber gaskets are one alternative used in CAAS.

Storage specifications

Assigning location codes

The exact location codes indicate the room, rack, shelf and tray/box numbers
Barcode system recommended where possible to implement.
Moveable shelves on tracks are preferred (moveable shelves make best use of space)

Storage conditions

-18 ± 3 ºC

Recording information during storage - Base collection

The following information should be recorded for each step:

Accession number
Number of containers
Location in genebank
Date of storage
Weight of the sample and/or number of the seeds
Total amount of seeds stored (by weight or number) or number of samples
Minimum amount of seeds allowed for distribution/regeneration
Initial germination percentage of the accession

Back to top

Active collection

Sample specifications

Minimum sample size for storage

The sample size of the active collection varies depending of the use of the collection and the anticipated request for distribution.
Examples of sample sizes for active collection storage:
- AVRDC: 1500, includes 20 user samples
- CAAS: 60g, used for characterization, evaluation, viability monitoring, multiplication, distribution
- CGN: 1800 seeds (6 distribution samples of 300 seeds each)
- IPK: 1000 – 2500 seeds
- NGB-NBPGR: 4000 seeds, used for distribution, regeneration, multiplication, characterization and evaluation.
- USDA: 2000 seeds (all seeds are used for distribution until meeting the lower threshold of 1000 seeds).

Minimum viability for storage

70% for cultivated species.
Wild relatives: 60%

Moisture content

3-7% (FAO/IPGRI genebank standards, 1994)
- NGB-NBPGR uses 7 % in active collection

Container specifications

Seed packaging method

Packing is best carried out in an air-conditioned room with controlled humidity (<=20% RH) as quick as possible after drying.
Exposure time of seeds to humidity – even if controlled – should be kept to a minimum.
Self adhesive water proof labels should be pasted on the outside of each packet.
The information on the external label should be duplicated on a label maintained inside the seed packet.
Labels should have the information on
Genus and species name
- Accession Number
- Collector Number
- Moisture Percentage
- Germination Percentage
- Seed number
- Date of storage
- Donor Institute

Specifications of packaging material

Most commonly used material are aluminium foil bags.
Alternatively are used rust-proof aluminum cans with screw caps and rubber gaskets, with diameter of 6.0 cm and height of 4.3cm (CAAS); high density polyethelyne containers with a screw-off lid and integral liquid seal for the active collection (SASA); or tightly closing glass jars (IPK)

Storage specifications

Assigning location codes

The exact location codes indicate the room, rack, shelf and tray/box numbers.
Barcode system recommended where possible to implement.
Moveable shelves on tracks are preferred (moveable shelves make best use of space)

Storage conditions

Storage conditions for the active collection vary between genebanks depending on the facilities, the environment and resources.
Genebanks that have the possibility to store the active collection at the same conditions as the base collection usually do so to reduce regenerations due to loss of viability.
Where this possibility does not exist or is not chosen, active collections are kept under controlled temperature above 0°C and controlled RH.
Examples for storage of active radish collections;
- AVRDC: + 4ºC without controlled RH, as samples are sealed in light vacuum conditions in aluminum foil bags;
- CAAS: +2 ºC and 30% RH
- IPK: stores the active collection at -15ºC like the base collection. If after preparation of a base sample, duplicate sample and active sample there is still seed left over of the accession, this seed is stored in a room at ambient conditions (i.e. without temperature and humidity control) in paper bags and used for distribution. Radish seeds can be stored under ambient conditions for about 5 years without significant decrease in viability.
- NGB-NPBGR: +4º - 8 ºC and 30 - 35% RH .Seeds are stored in paper bags or tri-layered aluminum packets (7% mc). Active collections usually represent germplasm that is maintained as base collection.

Recording information during storage – Active collection

The following information should be recorded for each step:

Accession number
Number of containers
Location in genebank
Date of storage
Weight of the sample and/or number of the seeds
Total amount of seeds stored (by weight or number) or number of samples
Minimum amount of seeds allowed for dissemination/regeneration

Back to top

References and further reading

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.

Vertucci CW, Roos EE.1990. Theoretical Basis of Protocols for Seed Storage. Plant Physiology, 94: 1019-1023. Available from: http://www.plantphysiol.org/cgi/reprint/94/3/1019. Date accessed: 4 June 2010.

Vertucci CW, Roos EE. 1993.Theoretical basis of protocols for seed storage II. The influence of temperature on optimal moisture levels. Seed Science Research, 3: 201-213. Available from: http://journals.cambridge.org/action/displayFulltext?type=1&fid=2205036&jid=SSR&volumeId=3&issueId=03&aid=1353180. Date accessed: 4 June 2010.