A long-day plant needs a long day and short night. If the long-day is interrupted by brief dark periods will it flower ?

Answer

To determine whether a long-day plant will flower if its long day is interrupted by brief dark periods, we can analyze the requirements for flowering in these plants step by step.

### Step-by-Step Solution:

1. **Understanding Long-Day Plants**: Long-day plants require longer periods of light (day) and shorter periods of darkness (night) to initiate flowering. The critical photoperiod is the minimum amount of light needed for flowering to occur.

2. **Identifying the Critical Period**: Each long-day plant has a specific critical period, which is the threshold of light duration needed for flowering. If the light period is longer than this critical period, flowering can occur.

3. **Effect of Interruption by Dark Periods**: If the long day is interrupted by brief dark periods, it means that the total light duration is effectively reduced. This interruption can extend the dark period beyond what is acceptable for the plant.

4. **Analyzing the Impact on Flowering**: When the dark period is extended and exceeds the critical requirement, the plant may not receive the adequate light necessary for flowering. This means that the plant will not meet its requirement for a long day and short night.

5. **Conclusion**: Since the long day has been interrupted by dark periods that extend beyond the critical period, the long-day plant will not flower under these conditions.

### Final Answer:
No, the long-day plant will not flower if the long day is interrupted by brief dark periods, as it does not meet the critical photoperiod requirement for flowering.

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