Which is not true for root pressure

Options

A. Positive hydrostatic pressure
B. Maximum during the day and minimum during night
C. Magnitude is 1-2 bars
D. Develops due to metabolic activity of roots

Answer

### Step-by-Step Solution

1. **Understanding Root Pressure**:
- Root pressure is a phenomenon observed in plants where a positive pressure builds up in the xylem sap of the roots. This pressure helps in the upward movement of water and nutrients from the roots to other parts of the plant.

2. **Identifying True Statements**:
- The first statement mentions that root pressure is a positive hydrostatic pressure. This is true as root pressure is indeed a positive pressure that pushes water upwards.
- The third statement states that the magnitude of root pressure is between 1 to 2 bars. This is also true as root pressure typically falls within this range.
- The fourth statement indicates that root pressure occurs due to the metabolic activity of the roots. This is correct as the roots actively engage in processes that contribute to the development of root pressure.

3. **Analyzing the False Statement**:
- The second statement claims that root pressure occurs maximum during the day and minimum during the night. This is false. In reality, root pressure is generally higher at night when transpiration rates are lower, and it decreases during the day due to increased transpiration.

4. **Conclusion**:
- Based on the analysis, the statement that is not true for root pressure is the one that suggests it is maximum during the day and minimum during the night.

### Final Answer
The statement that is not true for root pressure is: "It occurs maximum during the day and minimum during the night."

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