What is the action spectrum of transpiration?
(a) Blue and infra red
(b) Green and ultraviolet
(c) Orange and red
(d) Blue and red

Options

A. Blue and infra red
B. Green and ultraviolet
C. Orange and red
D. Blue and red

Answer

To determine the action spectrum of transpiration, we need to analyze the role of light in the process of transpiration, particularly focusing on the stomata.

### 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. **Role of Stomata**: Stomata are regulated by light. During the day, they open in response to light, allowing for gas exchange and transpiration to occur.

3. **Light Spectrum and Stomatal Opening**: The action spectrum refers to the range of wavelengths of light that are effective in causing a physiological response—in this case, the opening of stomata.

4. **Identifying Effective Wavelengths**: Research indicates that blue light (around 400-500 nm) is particularly effective in stimulating stomatal opening. Red light (around 600-700 nm) also contributes but is less effective compared to blue light.

5. **Conclusion**: Since the stomata open in response to both blue and red light, the action spectrum of transpiration is primarily associated with these two wavelengths.

6. **Final Answer**: Therefore, the action spectrum of transpiration is best described by option (d) Blue and Red.