Which of the following statements does not characterize photoperiodism?

Options

A. Mediated by florigen hormone.
B. Conversion of shoot apex into reproductive apex.
C. Red light is stimulatory in SDP, LDP, and DNP for flowering.
D. The number of correct photoperiodic induction may be 1-25

Answer

To determine which statement does not characterize photoperiodism, we need to analyze the options provided in the context of what photoperiodism entails. Here’s a step-by-step breakdown of the solution:

### Step-by-Step Solution:

1. **Understanding Photoperiodism**:
- Photoperiodism is the physiological reaction of organisms to the length of day or night. In plants, it specifically refers to how the duration of light exposure influences flowering and other developmental processes.

2. **Identifying Types of Plants Based on Photoperiod**:
- Plants can be categorized into three types based on their light requirements for flowering:
- **Short Day Plants (SDP)**: Require shorter daylight periods to flower.
- **Long Day Plants (LDP)**: Require longer daylight periods to flower.
- **Day Neutral Plants (DNP)**: Flower irrespective of the length of daylight.

3. **Analyzing the Statements**:
- The statements provided in the options need to be evaluated:
- **Mediated by Florigen**: This is correct as Florigen is a flowering hormone produced in leaves that signals flowering.
- **Conversion of shoot apex into reproductive apex**: This is also correct as photoperiodism leads to the transformation of the shoot apex into a reproductive structure.
- **Red light is stimulatory in SDP, LDP, and DNP for flowering**: This statement is incorrect. While red light can influence flowering, it does not act as a universal stimulant for all types of plants. Specifically, it does not stimulate SDP in the same way it might affect LDP.
- **Number of correct photoperiodic inductions may range from 1 to 25**: This statement is vague but can be interpreted as a characteristic of photoperiodism, as it suggests variability in flowering responses.

4. **Conclusion**:
- The statement that does not characterize photoperiodism is: **"Red light is stimulatory in SDP, LDP, and DNP for flowering."**

### Final Answer:
The statement that does not characterize photoperiodism is: **"Red light is stimulatory in SDP, LDP, and DNP for flowering."**

---