Question

For thinning in apples, the growth regulator used commercially is

• A. NAA
• B. 2,4-D
• C. Ethrel
• D. GA3

Hint:

NAA = Naphthaleneacetic acid (synthetic auxin).
Used for fruit thinning in apples, pears, and other fruits.
Improves fruit size and quality.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
This question tests knowledge of plant growth regulators in horticulture.

Step 2: Detailed Explanation:
For thinning in apples, NAA (Naphthaleneacetic acid) (A) is used commercially.
NAA is a synthetic auxin.
It causes abscission of young fruits, reducing fruit set and improving fruit size and quality.
2,4-D (B): A synthetic auxin, but not commonly used for apple thinning.
Ethrel (C): Releases ethylene, used for fruit ripening and thinning in some crops.
GA3 (D): Promotes elongation, used in some thinning applications.
Thus, NAA is the standard for apple thinning.

Step 3: Final Answer:
Thus, NAA is used for thinning in apples, which corresponds to option (A).
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