Seed Processing

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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 8. Monitoring 104 Handbooks for Genebanks No. 8 • Seeds of species known to have poor longevity, including most oily crops and ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

accessions with relatively low initial viability (85– 90% germination) in base collections, as well as all seeds stored in active collections under preferred conditions (see Table 6.2), should be monitored for viability after five years.

 • The interval between subsequent tests should be based on experience, and may be adjusted up or down depending on the extent of viability loss observed during the first monitoring test (see Table 8.1). Viability monitoring Viability is monitored by conducting a germination test on a fixed sample or by sequential germination (see Flowchart 8.1). Fixed sample size germination test For the fixed sample size germination test, it is recommended to use a ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

minimum of 200 seeds (as two replicates of 100 seeds). If the quantity is limited, 50–100 seeds can be tested in two replications. 1. Identify and list all accessions that require testing, and schedule the tests on a weekly or monthly basis (depending on availability of space in germinators and human resources). 2. Locate the containers in storage from the inventory. 3. Remove the containers from storage and leave them overnight at room temperature to warm. 4. Open each container, draw a sample of seeds for the test and immediately close the containers. 5. Conduct the germination tests using the methods and conditions described in Chapter 5. 6. Calculate the mean percentage germination from the results of the two replicates. Repeat the germination test if the difference ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

between the two replicates exceeds 10% or the maximum tolerance limits at 2.5% probability (see Ellis et al., 1985). • If the percentage germination is above 85% of the initial germination percentage, continue to store the accession. Fix the date for next test depending on the current percentage germination (see Table 8.1). • If the mean germination is below 85% of the initial germination percentage, schedule the accession for regeneration (see Table 8.2). Sequential germination tests The sequential germination test uses fewer seeds per replicate than the standard germination test. Otherwise, the methods and conditions for germination are the same as described for the fixed sample size germination test. Remember to update the seed quantity in the inventory database, deducting the number of seeds drawn for the germination test. Also, update the germination data in ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )

the inventory database after the final result is obtained. 105 Manual of Seed Handling CHECK THE FILES AND DETERMINE WHICH ACCESSIONS REQUIRE MONITORING PREPARE A LIST OF ALL ACCESSIONS WHICH REQUIRE MONITORING REMOVE CONTAINERS FROM THE STORE AND LEAVE THEM AT ROOM TEMPERATURE UNTIL THEY REACH AMBIENT TEMPERATURE Is it sequential testing? Is it fixed sample size testing? PREPARE TWO REPLICATES OF 50 OR 100 SEEDS PREPARE FIRST GROUP OF 40 SEEDS DECIDE ON THE METHOD OF TESTING TEST GERMINATION USING RECOMMENDED METHOD AND CONDITIONS TEST GERMINATION USING RECOMMENDED METHOD AND CONDITIONS ( Seed Processing, Seed Cleaning, Stone separator, Combo Cleaner, Grading Machine, Gravity Separator  )