Hydathodes open during :

Options

A. Light hours
B. Day hours
C. Noon hours
D. Always open

Answer

To answer the question "Hydathodes open during:", we need to understand the function and behavior of hydathodes in plants. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Definition of Hydathodes**:
- Hydathodes are specialized structures found on the leaf margins of some plants that facilitate the process of guttation, which is the exudation of water droplets.

**Hint**: Remember that hydathodes are associated with water movement in plants.

2. **Understanding Guttation**:
- Guttation occurs when the plant roots absorb more water than the plant can transpire. This excess water is expelled through the hydathodes.

**Hint**: Think about conditions when a plant might take up more water than it loses.

3. **Conditions for Hydathode Opening**:
- Hydathodes typically open during the night or early morning when transpiration rates are low due to cooler temperatures and higher humidity. This is when the pressure in the roots is higher, allowing water to be pushed out through the hydathodes.

**Hint**: Consider the time of day and environmental conditions that affect water loss in plants.

4. **Conclusion**:
- Therefore, hydathodes open primarily during the night or early morning when conditions are favorable for guttation.

**Hint**: Remember that the opening of hydathodes is linked to the plant's water management strategy.

### Final Answer:
Hydathodes open during the night or early morning.