Which accelerates the abscission in liower and fruit like thinning of cotton, cherry and walnut? 

Options

A. Auxin
B. ABA
C. GA3
D. Ethephon

Explanation

To determine which substance accelerates abscission in flowers and fruits, particularly in the thinning of cotton, cherry, and walnut, we can analyze the options provided: OXIN, ABA, GA3, and Ethepon.

### Step-by-Step Solution:

1. **Understand the Concept of Abscission**:
- Abscission refers to the process of shedding leaves, flowers, or fruits from a plant. It is a natural process that can be influenced by various plant hormones.

2. **Evaluate the First Option - OXIN**:
- OXIN (Auxin) is a plant growth regulator that primarily promotes cell elongation and is involved in apical dominance. It does not play a significant role in the abscission process.
- **Conclusion**: OXIN is not responsible for accelerating abscission.

3. **Evaluate the Second Option - ABA**:
- ABA (Abscisic Acid) is known as a stress hormone. It is involved in processes such as stomatal closure and responses to stress but does not directly promote abscission.
- **Conclusion**: ABA is also not responsible for accelerating abscission.

4. **Evaluate the Third Option - GA3**:
- GA3 (Gibberellic Acid) is primarily involved in promoting stem elongation and seed germination. It does not play a role in the abscission process.
- **Conclusion**: GA3 is not responsible for accelerating abscission.

5. **Evaluate the Fourth Option - Ethepon**:
- Ethepon is a plant growth regulator that promotes abscission. It is converted into ethylene in plants, which is a hormone known to induce abscission and fruit ripening. Ethepon is commonly used in agriculture, particularly for thinning cotton, cherries, and walnuts.
- **Conclusion**: Ethepon is the correct answer as it accelerates abscission.

### Final Answer:
The substance that accelerates the abscission in flowers and fruits, such as in the thinning of cotton, cherry, and walnut, is **Ethepon**.