Two factors which are inversely proportional to transpiration are

Options

A. Atmospheric pressure and relative humidity
B. Atmospheric pressure and temperature
C. Relative humidity and light
D. Relative humidity and root shoot ratio

Answer

To answer the question regarding the two factors that are inversely proportional to transpiration, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Transpiration**: Transpiration is the process by which water vapor is lost from the plant to the atmosphere, primarily through small openings in the leaves called stomata.

2. **Identifying Factors Affecting Transpiration**: Several environmental factors influence the rate of transpiration, including:
- Atmospheric pressure
- Relative humidity
- Temperature
- Light intensity
- Wind velocity

3. **Determining Inverse Proportionality**: Inverse proportionality means that as one factor increases, the other decreases. We need to identify which two factors among the options provided exhibit this relationship with transpiration.

4. **Analyzing Each Option**:
- **Option 1: Atmospheric Pressure and Relative Humidity**:
- If atmospheric pressure increases, transpiration decreases because higher pressure can reduce the gradient for water vapor to leave the plant.
- If relative humidity increases, transpiration also decreases because higher humidity means the air is already saturated with water vapor, reducing the gradient for water to evaporate from the plant.
- Therefore, both factors are inversely proportional to transpiration.

- **Option 2: Atmospheric Pressure and Temperature**:
- Atmospheric pressure can affect transpiration, but temperature usually has a direct relationship with transpiration (higher temperature increases transpiration).

- **Option 3: Relative Humidity and Light**:
- Relative humidity is inversely proportional, but light intensity generally increases transpiration.

- **Option 4: Relative Humidity and Root-Shoot Ratio**:
- Relative humidity is inversely proportional, but the root-shoot ratio typically affects the plant's ability to absorb water and is directly proportional to transpiration.

5. **Conclusion**: After analyzing the options, the only pair that is inversely proportional to transpiration is **Option 1: Atmospheric Pressure and Relative Humidity**.

### Final Answer:
The two factors which are inversely proportional to transpiration are **Atmospheric Pressure and Relative Humidity**.

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