In certain plants relative duration of light and dark period plays a important role in flowering

Answer

### Step-by-Step Solution:

1. **Understanding the Statement**: The question states that in certain plants, the relative duration of light and dark periods plays an important role in flowering.

2. **Identifying the Concept**: This phenomenon is known as **photoperiodism**. It refers to the response of plants to the lengths of day and night.

3. **Types of Plants Based on Photoperiodism**:
- **Short Day Plants (SDPs)**: These plants require a light period shorter than a certain critical length to flower. They typically bloom when the days are shorter, such as in late summer or fall.
- **Long Day Plants (LDPs)**: In contrast, these plants require a light period longer than a certain critical length to induce flowering. They usually flower in late spring or early summer when the days are longer.

4. **Conclusion**: Therefore, the statement is **true**. The relative duration of light and dark periods is indeed crucial for flowering in certain plants, specifically in short day and long day plants.