Photoperiodism affects

Options

A. Seed germination
B. Vegetative growth
C. Internode elongation
D. All of above.

Answer

### Step-by-Step Solution:

1. **Understanding Photoperiodism**:
- Photoperiodism is the physiological reaction of organisms to the length of day or night. In plants, it primarily influences flowering, seed germination, and growth patterns based on the duration of light and darkness they are exposed to.

2. **Effects on Seed Germination**:
- Photoperiodism affects seed germination by determining the optimal conditions for seeds to sprout. Certain seeds require specific light or dark periods to trigger germination.

3. **Influence on Vegetative Growth**:
- The growth of plants, particularly during the vegetative phase, is also influenced by photoperiodism. Different plants may grow better under long-day or short-day conditions, affecting their overall health and growth rate.

4. **Impact on Internode Elongation**:
- Internode elongation, which is the growth of the stem between nodes, is affected by the light exposure. Longer days can promote elongation in some plants, while shorter days may inhibit it.

5. **Conclusion**:
- Since photoperiodism affects seed germination, vegetative growth, and internode elongation, the correct answer to the question is "all of the above".

### Final Answer:
Photoperiodism affects seed germination, vegetative growth, and internode elongation. Therefore, the correct option is **all of the above**.

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