Chapter 23, Problem 25A

Summary Introduction

To write:The benefits of photoperiodism

Introduction:After examining that some plants only flowered at particular times of the year,scientists found that the main element affecting flowering was the amount of continuous darkness hours, not the amount of daylight hours. This flowering response is said to be Photoperiodism. Researchers classify flowering plants into four different groups. They are long-day plants, short-day plants, intermediate-day plants, or day-neutral plants.

Explanation of Solution

In phototropism, a plant bends or expands in response to the light directionally. Shoots typically move in the direction of the light; roots normally turn down. In photoperiodism flowering and other phases of growth are controlled in response to the photoperiod, or day-length.Short-day plants flower when the length of the day is below a certain threshold, while long-day plants flower when the length of the day is above a certain limit.

Conclusion

Thus, photoperiodism is regulated in many plants by the interaction between the day-length stimulus and the inner circadian rhythms of the plant.