Seed Technology and Varietal Selection
Seed Technology and Varietal Selection
This domain tests seed quality, seed classes, germination and purity testing, treatment, storage, and seed-rate calculation. Varietal selection questions ask you to match a variety to season, duration, resistance and market need.
Core rules and concepts
- Good seed has high genetic purity, physical purity, germination, vigour and health, with low moisture and no admixture.
- Germination percentage measures the proportion of pure seeds that produce normal seedlings; purity measures the proportion of the sample that is the desired seed. Vigour is the potential for rapid, uniform field establishment.
- Seed classes include breeder seed, foundation seed, certified seed and truthfully labelled seed. Certified seed is produced under prescribed standards; truthfully labelled seed is not certified.
- Seed treatment with fungicide or biofertilizer protects the seed or seedling, but it cannot rescue dead or badly damaged seed.
Worked example
Target 100 plants/m². Thousand-grain weight is 40 g, germination 90%, purity 98%, and field establishment 80%. Pure seed needed = 100 × 40 ÷ 1000 = 4 g/m². Divide by 0.90 × 0.98 × 0.80 = 0.7056. Seed rate = 4 ÷ 0.7056 = 5.67 g/m². For one hectare: 5.67 × 10,000 = 56.7 kg/ha. The reasoning is to correct for all three factors, not germination alone.
Traps that cost marks
Do not confuse purity with germination. Do not divide by only one correction factor. A high germination percentage does not guarantee high vigour. Certified seed is not the same as truthfully labelled seed, and a variety recommended for one season may fail in another.