Agricultural Biotechnology, Seed Science, and Crop Improvement
Core concepts
Understand the central dogma and the tools of modern biotechnology: DNA markers, marker-assisted selection, genetic transformation, gene editing, and tissue culture. Know the difference between conventional breeding (crossing and selection) and transgenic approaches, and the regulatory and biosafety considerations. Grasp seed science fundamentals: seed viability and vigor, germination testing, seed lot quality, purity, and the seed certification system (breeder, foundation, registered, certified seed). Understand hybrid seed production, cytoplasmic male sterility, and the difference between open-pollinated varieties and hybrids regarding seed saving. Know the principles of selection, heritability, and genotype-by-environment interaction.
Traps in questions
Do not confuse seed viability (ability to germinate) with seed vigor (ability to emerge and perform under stress). Remember that certified seed is the final class in the certification chain, not the first. Watch for confusion between marker-assisted selection (no foreign gene inserted) and genetic transformation (foreign gene inserted). Questions may test that hybrids generally require purchasing new seed each season because saved seed does not breed true.
Worked example
A seed lot has 90% germination and 95% purity. Pure live seed (PLS) = 0.90 × 0.95 = 0.855, or 85.5%. If the recommended PLS rate is 100 kg/ha, bulk seed to sow = 100 / 0.855 ≈ 117 kg/ha. Rule of thumb: PLS = germination × purity; divide the desired PLS rate by the PLS fraction to get bulk seed.
Rule of thumb
Separate breeding method (conventional, marker-assisted, transgenic) from seed class (breeder through certified) when answering.