Seed Multiplication Systems and Varietal Maintenance
Seed Multiplication Systems and Varietal Maintenance
This domain tests the seed chain from nucleus seed to certified seed, the generation limits and the maintenance practices that keep a variety true to type. Expect definitions, multiplication ratios and questions on who produces which seed class.
Seed classes and chain
- Nucleus seed is the purest source, maintained by the breeder or originating institution.
- Breeder seed is produced from nucleus seed under direct supervision and is the source for foundation seed.
- Foundation seed is produced from breeder seed; certified seed is produced from foundation seed.
- Truthfully labelled (TL) seed is sold with a label declaring quality, but it is not certification.
- Generation limits and crop-specific standards are set in the Indian Minimum Seed Certification Standards (IMSCS).
Varietal maintenance
Maintenance breeding keeps the variety's distinguishing characters: grow a small nucleus block, rogue off-types before flowering, harvest and store separately, keep records, and use grow-out tests to confirm purity. Avoid using certified seed to produce foundation seed; that reverses the chain.
Worked example
A breeder supplies 20 kg of breeder seed with a multiplication ratio of 1:60. Expected foundation seed = 20 × 60 = 1,200 kg. If field loss and processing reject 15%, usable foundation = 1,200 × 0.85 = 1,020 kg. That is the amount available for the next certified-seed crop, not 1,200 kg.
Traps that cost marks
Do not confuse breeder seed with foundation seed. Do not exceed generation limits. Do not mix lots from different fields. Do not treat a high multiplication ratio as a quality guarantee.