Question

Which one of the following activities is NOT practiced in the Bulk method of breeding?

• A. A large population is grown in every generation.
• B. \(F_2\) and subsequent generations are maintained and advanced as bulk.
• C. Off-season nurseries and greenhouse facilities are used to advance the generation.
• D. No pedigree records are maintained.

Hint:

The bulk method relies on natural environmental selection over multiple generations.
Growing populations in artificial greenhouse environments or off-season nurseries prevents natural selection from acting on the traits of interest.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The bulk breeding method is a plant breeding strategy for self-pollinated crops where segregating generations are grown in bulk until homozygous lines are isolated.

Step 2: Detailed Explanation:
In the bulk breeding method:
- A large population is grown in every generation (A) to preserve genetic diversity and maximize the chances of recovering desirable recombinants.
- The \(F_2\) and subsequent segregating generations are harvested and advanced as a mixed bulk (B) rather than selecting individual plants.
- Because the population is handled as a single bulk without selecting individual plants, no pedigree records are maintained (D) during the bulk stages, which simplifies field management.
- The primary advantage of the bulk method is that it allows natural selection to act on the population over several generations, eliminating less fit genotypes.
To allow natural selection to operate effectively, the bulk population must be grown under representative natural field conditions.
Growing the bulk population in off-season nurseries or controlled greenhouse facilities (C) shields the plants from natural selection, defeating the primary purpose of the bulk breeding strategy.
Therefore, using greenhouses and off-season nurseries to advance generations is not practiced in bulk breeding.

Step 3: Final Answer:
The correct option is (C).