In short day plants (SDP) flowering is induced by

Options

A. short day and uninterrupted long night
B. short night
C. long day and uninterrupted night
D. none

Explanation

**Step-by-Step Solution:**

1. **Understanding Short Day Plants (SDP):**
- Short day plants are those that require a shorter duration of light (day) and a longer duration of darkness (night) to induce flowering.

2. **Critical Photoperiod:**
- Each plant has a specific critical photoperiod, which is the maximum duration of light it can receive to trigger flowering. For short day plants, this means that the light period must be shorter than this critical length.

3. **Role of Night Duration:**
- For flowering to occur in short day plants, they require an uninterrupted long night. This means that the dark period must be long enough and continuous without interruptions.

4. **Evaluating the Options:**
- **Option 1:** Short day and uninterrupted long night - This is correct as SDPs need a longer dark period.
- **Option 2:** Short night - This is incorrect as SDPs require a long night.
- **Option 3:** Long day and uninterrupted night - This is incorrect as SDPs do not flower under long day conditions.
- **Option 4:** None of these - This is incorrect since option 1 is valid.

5. **Conclusion:**
- The correct answer is that flowering in short day plants is induced by "short day and uninterrupted long night."

**Final Answer:**
- The correct option is: **Short day and uninterrupted long night.**

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