Hormone involved in breaking dormancy of winter buds is

Options

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

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks for the hormone that is involved in breaking the dormancy of winter buds. Dormancy in plants is a period when growth and development are temporarily halted.

2. **Identifying the Hormones**: The options provided are:
- Ethylene
- Gibberellin
- Auxin
- Cytokinin

3. **Analyzing Gibberellin**: Gibberellin is known to play a significant role in various developmental processes in plants. It is particularly important for:
- Stem elongation
- Seed germination
- Breaking dormancy in buds

4. **Understanding Dormancy Induction**: Dormancy in winter buds typically begins after the leaves have fallen. This means that the plant enters a state of dormancy during the winter months.

5. **Breaking Dormancy**: To break this dormancy, gibberellin can be applied externally (exogenously). This hormone helps to initiate growth processes that were halted during the dormancy period.

6. **Evaluating Other Hormones**:
- **Auxins**: These are primarily involved in the growth of plant tips and do not specifically break dormancy.
- **Cytokinins**: These hormones are mainly responsible for cell division and do not play a direct role in breaking dormancy.
- **Ethylene**: This hormone is known as a growth inhibitor and does not promote the breaking of dormancy.

7. **Conclusion**: Based on the analysis, the hormone involved in breaking the dormancy of winter buds is **Gibberellin**.

**Final Answer**: Gibberellin

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