Question

What is the site of perception for photoperiodism induction in plants?

• A. Roots
• B. Leaves
• C. Stem apex
• D. Flowers

Hint:

Leaves perceive day length using phytochrome pigments and send flowering signals (florigen) to the shoot apex.

Answer 1

The Correct Option is B

Topic - Biology: Plant Growth and Development
Step 1: Understanding the Question:
The question asks which part of the plant is responsible for detecting the duration of light and dark (photoperiod) to trigger flowering.
Step 2: Detailed Explanation:
Photoperiodism is the physiological reaction of organisms to the length of night or a dark period.
1. Leaves: Experiments have shown that leaves are the organs that perceive the photoperiodic stimulus. They contain the pigment phytochrome which senses light changes.

2. Mechanism: Once the leaves perceive the correct photoperiod, a hypothetical hormone-like signal called florigen is produced.

3. Translocation: This signal is then translocated from the leaves to the shoot apical meristem (stem apex).

4. Action: The shoot apex then transforms into a flowering apex. Although the change happens at the apex, the perception is in the leaves.
Step 3: Final Answer:
The site of perception for photoperiodism is the Leaves.