Leaf fall can be prevented by

Options

A. Florigen
B. Auxin
C. Cytokinin
D. Abscisic acid

Answer

**Step-by-Step Solution:**

1. **Understanding Leaf Fall**: Leaf fall, also known as abscission, is a natural process in plants where leaves detach from the stem. This process can be influenced by various factors, including environmental conditions and hormonal changes in the plant.

2. **Identifying Plant Hormones**: The question asks which plant hormone can prevent leaf fall. The options provided are:
- Florigen
- Auxin
- Cytokinin
- Abscisic Acid

3. **Analyzing Each Hormone**:
- **Florigen**: This hormone is primarily involved in the flowering process. It promotes flowering but does not play a role in preventing leaf fall. Thus, it is not the correct answer.
- **Auxin**: This hormone is known for promoting stem elongation and inhibiting the growth of lateral buds (apical dominance). While auxins have various roles in plant growth, they do not specifically prevent leaf fall. Therefore, this option is also incorrect.
- **Cytokinin**: This hormone is known for delaying senescence (aging) in plants. It helps in the retention of leaves by delaying the breakdown of chlorophyll and other cellular components. This action effectively reduces leaf fall, making cytokinin the correct answer.
- **Abscisic Acid**: This hormone is involved in stress responses, particularly in regulating water loss by mediating stomatal closure. It does not prevent leaf fall; instead, it can promote it under stress conditions.

4. **Conclusion**: Based on the analysis, the hormone that can prevent leaf fall is **Cytokinin**.

**Final Answer**: Cytokinin

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