Which of the following exerts profound effect on the reproductive growth of a flowering plant?

Options

A. Quality of light
B. Quantity of light
C. Direction of light
D. Duration of light cycles

Answer

To determine which factor exerts a profound effect on the reproductive growth of flowering plants, we need to analyze the options provided:

1. **Quality of Light**: This refers to the specific wavelengths of light that plants receive. While quality can influence certain aspects of plant growth, it does not directly dictate reproductive growth.

2. **Quantity of Light**: This refers to the intensity or amount of light that plants receive. Like quality, while it plays a role in overall plant health, it is not the primary factor influencing reproductive growth.

3. **Direction of Light**: This pertains to the angle at which light reaches the plant. While it can affect growth patterns (like phototropism), it does not significantly impact the reproductive phase.

4. **Duration of Light Cycle**: This is related to photoperiodism, which is the response of plants to the relative lengths of day and night. This factor is crucial for flowering in many plants, as it determines when they will enter their reproductive phase. Different plants have varying requirements for light duration to trigger flowering, categorizing them into short-day, long-day, intermediate-day, and day-neutral plants.

Given this analysis, the factor that exerts a profound effect on the reproductive growth of flowering plants is:

**Answer: D. Duration of light cycle**

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