How does colored light affect plant growth?

How different colors of light affect plant growth?

• I am working on a science fair project. I understand that plants need photosynthesis to grow and that different spectrums of light are absorbed differently by the plant. I need help with my theoretical background and my purpose and hypothesis. If anyone have ever done this project or would like to help me that would be great :) Thanks so you much.

• Answer:

  Violet, blue and a small portion of red light produces the greatest photosynthetic rate (most growth). A couple of factors to be considered is insuring the light intensity is equal for all colors of light to which the plants are exposed. An accurate light meter is a must piece of equipment. Second, you need to have multiple plants exposed to each different color of light to eliminate random chance events. Third you need to make sure the measure of the rate of photosynthesis is accurate. Best measure would be to compare dry weights of each test group as compare to the control groups' dry weight. This is done by carefully cleaning away the potting soil from each plant, drying the plants in a low temperature heated oven, weighing each plant group to get total weight. The better the photosynthetic rate the more biomass there should be.