Seed Processing

Dry seeds will reabsorb moisture from more humid ambient air. Therefore, seeds should be packaged in waterproof containers and hermetically sealed without delay following removal from the drying room or cabinet. Types of container Different types of container are available for packaging; the choice depends on storage conditions and species. It is important that the packing material be completely impermeable to water and suitable for long-term use. Frequently used containers include glass bottles, aluminium cans, laminated aluminium foil packets and plastic bottles. Different types of container each have advantages and disadvantages. Glass bottles are good ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

but can easily break. Aluminium cans are difficult to reseal once they have been opened. Aluminium foil packets can be resealed and occupy less space than other containers, but seeds with 1. Introduction 2. Germplasm acquisition and registration 2.1 Germplasm acquisition 2.2 Germplasm registration 3. Seed cleaning 4. Seed moisture content determination and drying 4.1 Seed moisture content determination 4.2 Seed drying 5. Seed quality testing 5.1 Seed viability testing 5.2 Seed health testing 5.3 Seed testing for inadvertent introduction of transgenes 6. Seed packaging and storage 6.1 Seed packaging 6.2 Seed storage 7. Germplasm distribution 8. Germplasm monitoring and regeneration 8.1 Germplasm monitoring 8.2 Germplasm regeneration 6. Seed storage 87 Manual of Seed Handling VISUALLY CHECK THE CONTAINERS PREPARE INSIDE AND OUTSIDE LABELS WEIGH ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

OUT SAMPLE OF SEEDS TO FIT THE CONTAINER Is the container below standard? DISCARD IT YES CHECK WHETHER THE ACCESSION SHOULD BE PLACED IN MORE THAN ONE CONTAINER LABEL THE CONTAINER(S) SEAL THE CONTAINERS Will the accession be placed in one container? PRINT OUT THE ADDITIONAL LABELS NEEDED NO VISUALLY CHECK IF EACH CONTAINER IS CORRECTLY SEALED Does the container have a lEAk PLACE THE CONTAINERS IN THE STORAGE ROOM FILE DATA OF EACH ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

ACCESSION NO YES NO YES Flowchart 6.1. Seed packaging. PROCEED TO FILL THE CONTAINERS AND ADD THE INSIDE LABEL sharp projections can pierce them and moisture can leak inside. Plastic bottles and aluminium cans with lids are moisture resistant but not moisture proof unless they have a tight rubber seal. They should be used with caution if the RH of the storage room is not controlled. 88 Handbooks for Genebanks No. 8 Testing quality of containers The quality and sealing capacity of containers can be tested as follows: 1. Fill the containers with regenerated self-indicating silica gel and seal it in the same way in which seeds are stored. 2. Accurately determine the weight of the containers with an analytical balance. 3. Hold the containers over water (but not touching it) in a desiccator for about a week. 4. Remove the containers from the desiccator and allow the surface to dry. 5. Weigh the containers, record the change in weight and examine the colour of the silica gel. • If the weight of the containers remains constant, then they are moisture proof and the seal is good. • If ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

the weight of the containers increases and the silica gel has turned pale blue or pink, then they are of poor quality or the seal is leaking moisture. 6. Adjust the seal and repeat the test to confirm the quality of the containers. A container’s quality can also be tested by filling it with water and holding it over silica gel in a desiccator or in a ventilated oven at 40°C for one to two weeks. A change in the container’s weight indicates poor quality or leakage in sealing. How many seeds should be packed? The number of seeds to be packed for storage will depend on the species being conserved and how often seeds will be removed for monitoring, distribution or regeneration. The FAO/IPGRI Genebank Standards (1994) recommend that for material which shows little morphological variation (genetically homogenous accessions), 3000 seeds are acceptable, but 4000 seeds are preferable to represent each accession.