Question

Which of the following annuals require the isolation distance of 50-100 meters for seed production?
(A) Antirrhinum
(B) Marigold
(C) Larkspur
(D) Nasturtium
Choose the correct answer from the options given below:

• A. (A), (B) and (C) only.
• B. (A) and (C) only.
• C. (B), (C) and (D) only.
• D. (A) and (D) only.

Hint:

Isolation distance for seed production depends on how easily a plant cross-pollinates.
Highly cross-pollinated (by wind or insects): Need larger distances.
Mostly self-pollinated: Need smaller distances. Antirrhinum (snapdragon) and Larkspur are known to be significantly cross-pollinated by insects, thus requiring good isolation like 50-100m.

Answer 1

The Correct Option is B

Step 1: Antirrhinum and Larkspur are strongly bee cross-pollinated, needing wide isolation.
Step 2: Marigold is mostly self-pollinated, needing much less isolation.
Step 3: Nasturtium needs less isolation than the two strong outcrossers.
Step 4: Correct answer: (A) and (C) only.