A long day plant is

Options

A. Wheat
B. Soyabeam
C. Tobacco
D. Xanthium

Answer

**Step-by-Step Solution:**

1. **Definition of Long Day Plants (LDPs):**
Long day plants are those that require a longer duration of light (photo period) to flower and grow properly. They typically bloom when the daylight hours exceed a certain threshold.

2. **Characteristics of Long Day Plants:**
- They thrive in conditions where the daylight duration is longer than a specific number of hours, usually more than 12-14 hours.
- These plants are often adapted to grow in regions where summer days are longer.

3. **Examples of Long Day Plants:**
- Common examples include wheat, sugar beet, and barley. These plants are known to flower and produce seeds effectively under long daylight conditions.

4. **Comparison with Short Day Plants (SDPs):**
- In contrast, short day plants require shorter daylight periods (less than 12 hours) to flower. An example of a short day plant is an thymum.

5. **Conclusion:**
- Therefore, a long day plant is characterized by its requirement for extended daylight to promote flowering, with wheat being a prime example.

**Final Answer:**
A long day plant is wheat, which has a long photo period duration.

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