Photoperidism was discovered by

Options

A. Van Overbeek
B. Lysenko
C. Garnar and Allard
D. Boysen- Jensen and Paal

Answer

**Step-by-Step Solution:**

1. **Understanding Photoperiodism**: Photoperiodism is a biological phenomenon in which plants respond to the length of day or night. It is crucial for determining the timing of flowering in various plant species.

2. **Historical Context**: Initially, it was believed that the length of daylight was the primary factor influencing flowering. However, research has shown that it is actually the length of the night (darkness) that plays a significant role.

3. **Key Researchers**: The concept of photoperiodism was significantly advanced by the research conducted by two scientists, Garner and Allard. They conducted experiments that helped clarify how plants respond to light and dark periods.

4. **Types of Photoperiodic Plants**:
- **Short Day Plants**: These plants require shorter daylight hours to flower, typically blooming when nights are longer. An example is Chrysanthemum.
- **Long Day Plants**: These plants require longer daylight hours and shorter nights to flower. Examples include potato and spinach.
- **Day-Neutral Plants**: These plants do not depend on the length of day or night for flowering. Examples include tomato and strawberries.

5. **Conclusion**: Based on the research and experiments conducted by Garner and Allard, the correct answer to the question "Photoperiodism was discovered by" is **Garner and Allard**.

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