Seed Processing

A genebank may opt to maintain one sample of each accession for both conservation (in a base ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

collection) and utilization (in an active collection) as long as the maintenance cost is not too high. If the genebank maintains both base and active collections, it is more cost effective to store only those accessions in the active collection that are being used by breeders and other users. (For further information, see Engels and Visser, 2003.) Type of storage facility The two commonly available ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

options for seed storage are walk-in cold stores and freezers. The choice depends on the number of accessions to be stored, seed size and storage temperatures selected. When collections are small and sub-zero temperatures are required, chest or upright freezers are a cheaper option for seed storage. How is storage space organized? The organization of storage space depends on the type of storage facility and the type of containers used in the genebank. In view of the cost of maintaining cold storage, the space should be optimized so that a maximum number of seed accessions can be stored. Walk-in cold storage If the genebank has a walk-in cold store, the best option is to use 93 Manual of ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

Seed Handling moveable racks that maximize storage space. Each rack is divided into a number of shelves. The distance between each shelf will depend of the size of containers. Small containers or aluminium foil bags can be held in boxes or trays and placed on the shelves. A coding system can help genebank staff to locate accessions readily for sample retrieval; coding can be computerized in a database or stock inventory system. For example, ‘A010201’ could be used to indicate the following location: • Room number (if more than one storage room is being used): A • Rack number: 01 • Shelf number: 02 • Tray/box number: 01 Chest or upright freezers For genebanks using chest or upright ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

freezers, containers that fit onto shelves or boxes holding individual small containers can be used to store accessions. As for cold storage, a coding system to help locating accession can be established, including freezer number, row number and box number. Storing seed samples Step 1: Check the number of seeds in the accession 1. Weigh the seeds of each accession. Convert the seed weights to numbers by using the 100-seed or 1000-seed weight as described in the previous section. 2. Verify if the sample contains more than the required number of seeds for a genetically homogenous sample (3000–4000 seeds) or a genetically heterogenous sample (4000–12 000 seeds). 3. If the sample contains less than the required amount, either proceed directly to regeneration or store temporarily in the genebank and regenerate at the earliest opportunity (see Chapter 8). Step 2: Identify a location for storage The next step is to determine the location inside the storage room or freezer in which the accession will be stored. 1. ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

2. Assign the space where the accession is to be placed. If the accession is stored in more than one container, keep them all together. Step 3: Place seeds in store 1. Make a list of assigned spaces where each accession will be placed. 2. Place the containers in the storage room or freezer in their assigned locations. 94 Handbooks for Genebanks No. 8 Step 4: Enter data into the database 1. Enter the data regarding storage location, date and number of containers in the inventory file. Safety duplication (security backup collection) Safety duplication means a genetically identical sub-sample of the accession is stored at another location (preferably outside the country) to provide insurance ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

against loss of material. Safety duplication includes both the duplication of material and its related information.