Which is not true for root pressure

Options

A. Positive hydrostatic pressure.
B. Maximum during the day and minimum during night.
C. Responsible for guttation
D. Develops due to metabolic activity of roots.

Answer

To determine which statement is not true regarding root pressure, we can analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Root Pressure**:
- Root pressure is the positive hydrostatic pressure developed in the roots of plants. It is a result of osmotic pressure and the accumulation of water in the roots when soil moisture is high.

2. **Analyzing the Options**:
- **Option 1**: Positive hydrostatic pressure.
- This statement is true. Root pressure is indeed a positive hydrostatic pressure that develops in the roots.

- **Option 2**: Maximum during the day and minimum during the night.
- This statement is not true. Root pressure is generally maximum during the night when transpiration is low and soil moisture is high. During the day, transpiration increases, which can reduce root pressure.

- **Option 3**: Responsible for guttation.
- This statement is true. Root pressure contributes to guttation, which is the exudation of water droplets from the tips or edges of leaves.

- **Option 4**: Develops due to metabolic activity of roots.
- This statement is also true. The metabolic activities of roots, including the uptake of nutrients and water, contribute to the development of root pressure.

3. **Conclusion**:
- The statement that is not true for root pressure is: "Maximum during the day and minimum during the night."

### Final Answer:
The correct answer is: **Maximum during the day and minimum during the night** (this statement is not true for root pressure).

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