Question

Which of the following is related to photoperiodical classification of plants?
A. Short day plants
B. Long day plants
C. Day neutral plants
D. Vernalization
Choose the correct answer from the options given below:

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

Hint:

Photoperiodism refers to light duration responses (Short day, Long day, Day neutral). Vernalization refers to temperature responses (specifically cold-induced flowering) and is not part of photoperiodic classification.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Photoperiodism is the physiological reaction of organisms (specifically plants) to the length of day or night.
It determines when a plant shifts from vegetative growth to reproductive growth (flowering).
Plants are classified into distinct categories based on their photoperiodic requirements.
Vernalization, on the other hand, is a temperature-dependent process rather than a light-duration dependent process.

Step 2: Detailed Explanation:
The photoperiodic response in plants is primarily regulated by the pigment phytochrome, which senses the duration of darkness.
Based on this response, plants are classified into:
1. Short-day plants (SDPs): These plants flower only when the day length is shorter than a critical threshold (e.g., rice, soybeans, chrysanthemums).
They actually require a continuous, uninterrupted dark period of a minimum duration.
2. Long-day plants (LDPs): These plants flower when the day length exceeds a critical threshold (e.g., wheat, barley, spinach).
They require shorter dark periods to trigger flowering.
3. Day-neutral plants (DNPs): These plants flower regardless of the day length, relying instead on age or structural maturity (e.g., tomato, cucumber, maize).
Vernalization (D) is the induction of a plant's flowering process by exposure to the prolonged cold of winter.
While vernalization and photoperiodism often work together to ensure plants flower at the correct time of year, vernalization itself is a thermal classification, not a photoperiodic one.
Therefore, only A, B, and C are related to photoperiodic classification.

Step 3: Final Answer
The components related to the photoperiodical classification of plants are A, B, and C only.