A. In dry atmosphere , the relative humidity is low, so the rate of transpiration increases
B. Slow breeze promotes the rate of transpiration
C. ABA promotes transpiration
D. A high salt concentration in soil water increases transpiration

Options

A. C and D are correct
B. B and C are correct
C. A and C are correct
D. A and B are correct

Answer

To analyze the statements regarding transpiration in plants, we will evaluate each statement one by one.

### Step-by-Step Solution:

1. **Statement A: In dry atmosphere, the relative humidity is low, so the rate of transpiration increases.**
- **Explanation:** In a dry atmosphere, the relative humidity is low, which means that the concentration of water vapor in the air is lower compared to that inside the plant. Water vapor moves from an area of higher concentration (inside the plant) to an area of lower concentration (the surrounding air). Therefore, transpiration, which is the loss of water vapor from the plant, increases in dry conditions.
- **Conclusion:** This statement is **true**.

2. **Statement B: Slow breeze promotes the rate of transpiration.**
- **Explanation:** A slow breeze helps to remove the water vapor that accumulates around the stomata of the plant. By moving this vapor away, the concentration gradient between the inside of the plant and the outside air is maintained, which facilitates further loss of water vapor. Thus, a slow breeze can indeed promote transpiration.
- **Conclusion:** This statement is **true**.

3. **Statement C: ABA promotes transpiration.**
- **Explanation:** Abscisic acid (ABA) is a plant hormone that is produced in response to stress conditions, such as drought. When a plant is under stress, ABA signals the stomata to close to conserve water, thereby reducing transpiration. Therefore, ABA does not promote transpiration; it actually inhibits it.
- **Conclusion:** This statement is **false**.

4. **Statement D: A high salt concentration in soil water increases transpiration.**
- **Explanation:** High salt concentration in soil can lead to osmotic stress, making it difficult for plants to absorb water. When plants cannot take up enough water, they will also reduce transpiration to conserve the limited water they have. Thus, a high salt concentration does not increase transpiration.
- **Conclusion:** This statement is **false**.

### Final Summary:
- **Correct Statements:** A and B
- **Incorrect Statements:** C and D