Science fair experiment, help!?

Question

I did my science fair on how the different colors of light affect the production of chlorophyll in the leaves of a common houseplant (philodendron.) I found this topic on a website that also had an experiment where you cover the leaves with sleeves (transperency film) of the different colors of light. (red, green, blue, yellow, clear, and black.) It said to keep the sleeves on the leaves for one week than to record your results in a table of how much chlorophyll each leave produced. I did this one 10 plants and was not pleased with my results. I concluded that it went in this order of what color produced the most chlorophyll: clear, red, yellow, green, blue, then black. This may sound right but studies show that it should go: clear, red, blue, green, yellow, black. I am doing this experiment for another week, but am afraid to get the same results. Why do you think I got these results? By the way, its been very cold where I live (middle of winter) but the plants are still inside! Help!

Answer 1

Riley, Don't be too fast to worry about your results. I'd say that your experiment is doing pretty well. You are showing the extremes, both the high and low results right. The middle range is going to be a lot harder to show exactly right, especially with the quality of inside lights. Very likely in plants grown in the sunshine you would get different results. By applying the different colored sleeves what you are doing is controlling the wave length of light filtered out. For example clear is filtering out none, black filters out all light, red filters out red light, etc. What you are not controlling is the quality or wave length of light getting through to the plant because you have no control of the quality of your inside lights. This very likely will explain your results and your results are not necessarily wrong. Explain that your results would probably have been different in sunlight or lights like Grolux light, which try to duplicate sunlight in wave length. Best of luck. I think you are doing a good job under the circumstances you have to work with, and I think your teacher will as well.