Question

The plants that require exposure to light for a period longer than a critical duration are called

• A. Short-day plants
• B. Long-day plants
• C. Day-neutral plants
• D. Sort-long-day plants

Hint:

Long-day plants: Flower when day length > critical.
Short-day plants: Flower when day length < critical.
Day-neutral plants: Independent of day length.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
This question tests knowledge of photoperiodism.

Step 2: Detailed Explanation:
Long-day plants require exposure to light for a period longer than a critical duration to flower.
Examples: Spinach, Radish, Wheat, Barley.
Short-day plants (A): Require light period shorter than a critical duration (e.g., Soybean, Chrysanthemum).
Day-neutral plants (C): Flowering is independent of day length (e.g., Tomato, Rice).
Sort-long-day plants (D): Not a standard term.
Thus, plants requiring longer than critical light duration are long-day plants.

Step 3: Final Answer:
Thus, plants requiring light longer than critical duration are long-day plants, which corresponds to option (B).
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