Control of leaf, flower and fruit abscission and promotion of fruit ripening are functions of

Options

A. Ethylene
B. Auxin
C. Gibberellin
D. Cytokinin.

Answer

**Step-by-Step Solution:**

1. **Understanding Plant Hormones:**
- Plants have various hormones known as phytohormones or plant growth regulators that control physiological functions.
- The main hormones involved in leaf, flower, and fruit abscission, as well as fruit ripening, are auxin, ethylene, abscisic acid (ABA), and others.

2. **Identifying Functions of Auxin:**
- Auxin is responsible for preventing premature fruit drop and leaf drop. It plays a role in maintaining the attachment of leaves and fruits to the plant.

3. **Role of Ethylene:**
- Ethylene is a gaseous hormone that promotes the abscission (dropping) of leaves, flowers, and fruits. It is particularly important in the ripening of fruits.
- Ethylene triggers the process of fruit ripening, especially in climacteric fruits, which are characterized by a rapid increase in respiration rate during ripening.

4. **Influence of Abscisic Acid (ABA):**
- ABA is known as the stress hormone and is released under unfavorable environmental conditions. It can influence the abscission process indirectly through ethylene.

5. **Conclusion:**
- The control of leaf, flower, and fruit abscission, along with the promotion of fruit ripening, is primarily the function of ethylene.
- Therefore, the correct answer to the question is ethylene.

**Final Answer:**
The control of leaf, flower, and fruit abscission and promotion of fruit ripening are functions of **ethylene**.

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