Question:
Which one of the following growth regulator is involved in reducing transpiration under water-stress conditions in crop plants?
Which one of the following growth regulator is involved in reducing transpiration under water-stress conditions in crop plants?
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ABA = "Stress Hormone."
Think of ABA as the "Brake" of the plant—it stops growth and closes stomata to survive harsh conditions.
Think of ABA as the "Brake" of the plant—it stops growth and closes stomata to survive harsh conditions.
Updated On: Aug 21, 2026
- Gibberellins
- Cytokinin
- Abscisic acid
- Auxin
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The Correct Option is C
Solution and Explanation
Step 1: Understanding the Question:
The question asks to identify the plant hormone that acts as a survival signal during drought or water scarcity, specifically by closing stomata to reduce water loss (transpiration).
Detailed Explanation:
• Abscisic Acid (ABA) - The Stress Hormone:
ABA is primarily synthesized in response to environmental stresses, particularly drought.
• Mechanism of Action:
When a plant experiences water stress, ABA levels rise in the leaves.
ABA binds to receptors on the guard cells of stomata, triggering an efflux of Potassium (\(K^+\)) and other ions.
This leads to an increase in the osmotic potential of the guard cells, causing water to leave them. The guard cells lose turgor and collapse, effectively closing the stomatal pore.
• Result:
Stomatal closure significantly reduces the amount of water vapor escaping from the leaf (transpiration), helping the plant conserve its limited water supply.
Step 2: Final Answer:
Abscisic acid (ABA) is the hormone responsible for stomatal closure during water stress.
The question asks to identify the plant hormone that acts as a survival signal during drought or water scarcity, specifically by closing stomata to reduce water loss (transpiration).
Detailed Explanation:
• Abscisic Acid (ABA) - The Stress Hormone:
ABA is primarily synthesized in response to environmental stresses, particularly drought.
• Mechanism of Action:
When a plant experiences water stress, ABA levels rise in the leaves.
ABA binds to receptors on the guard cells of stomata, triggering an efflux of Potassium (\(K^+\)) and other ions.
This leads to an increase in the osmotic potential of the guard cells, causing water to leave them. The guard cells lose turgor and collapse, effectively closing the stomatal pore.
• Result:
Stomatal closure significantly reduces the amount of water vapor escaping from the leaf (transpiration), helping the plant conserve its limited water supply.
Step 2: Final Answer:
Abscisic acid (ABA) is the hormone responsible for stomatal closure during water stress.
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