Seed Production and Quality Control
Seed Production and Quality Control - This domain tests seed classes, isolation distance, roguing, field inspection, genetic purity and certification.
Core rules
- Seed classes: nucleus, breeder, foundation, certified and truthfully labelled seed; each has a defined generation and quality standard.
- Isolation distance prevents cross-pollination and mechanical mixture; it is short for self-pollinated crops and long for cross-pollinated crops such as maize.
- Roguing removes off-types, diseased plants and other crop plants before flowering.
- Field inspection checks isolation, off-types, disease and weed contamination; laboratory tests check purity, germination and moisture.
- A grow-out test confirms genetic purity by raising a sample and observing plant characters.
- Certification is voluntary; truthfully labelled seed carries a label but is not certified.
Worked example
In a field of 1,000 plants, 8 off-types are counted. Genetic purity = (1000 − 8) ÷ 1000 × 100 = 99.2%. If the certification standard is 99.0%, the field passes on this count. Reasoning: off-types are subtracted from the total; the result is compared with the prescribed standard, not with the previous inspection.
Traps
- Do not confuse foundation seed with certified seed; foundation is the parent of certified seed.
- Isolation distance is not the same as spacing between plants.
- One roguing is rarely enough; repeat before flowering and at maturity.
- Truthfully labelled seed is not certified seed.
- Certification is voluntary, not compulsory for all seed sold.