The most widely used compound as source of ethylene is

Answer

**Step-by-Step Solution:**

1. **Understanding Ethylene**: Ethylene is a gaseous plant growth regulator that plays a crucial role in various physiological processes in plants, including fruit ripening and abscission (the shedding of leaves, flowers, or fruits).

2. **Functions of Ethylene**:
- It hastens the ripening of fruits, making them ready for consumption.
- It promotes abscission in flowers and leaves, which is important for the plant's growth cycle.
- In female cucumber plants, ethylene increases the yield, enhancing productivity.

3. **Identifying the Source of Ethylene**:
- The question asks for the most widely used compound as a source of ethylene.
- Among various compounds, Ethephon is recognized as a significant source of ethylene.

4. **Why Ethephon?**:
- Ethephon is readily absorbed by plants, which allows it to be transported efficiently within the plant system.
- It releases ethylene slowly, providing a controlled release that aligns with the plant's requirements.

5. **Conclusion**: Therefore, the most widely used compound as a source of ethylene is **Ethephon**.

---