Red, Blue, Yellow
A study of Photosynthesis and the effect of colored light on the growth of lima bean plants.
In my study, I planted 4 groups (each group containing 2 lima bean plants, separated) to discover under which color light the plants would grow best: Red, blue, yellow, or the control, regular white light. First, I prepared the Styrofoam cups by putting a layer of sand and small pebbles for drainage purposes, as not to drown the plants when I watered them. Lima beans do not need very wet soil. I planted the lima beans 1 inch deep in potting soil. Also, I watered the plants every 2-3 days and took pictures often to compare the growth of the plants. I put 1 plant from each set under the appropriate color light, and let it sprout. The other 1 I allowed to sprout under regular light, then put under the appropriate light. I believed that the blue light should grow the tallest plant because blue light is absorbed best by green plants. Blue light has the shortest wavelength, and therefore more energy for photosynthesis. Red light should grow next tallest, followed by yellow light. When I first completed the experiment, the control plant grew the tallest and was healthy looking. The red and yellow plants grew fairly tall and were health looking. The blue plants were tall, but spindly, yellow and sickly looking, with leaves not full and open. My results were different from my hypothesis, so I repeated the experiment for another 4 weeks, and the results were identical. Possible explanations for this could be a difference in the pigment of light bulbs I used, different quality of the lima bean seeds, or that the plants had no "dark period," which is required in some plant growth.
The conclusion I have drawn from this experiment is that plants will grow best when exposed to regular WHITE light, that has all wavelengths of color in it. Also, after doing this experiment, I have reached the conclusion that plants should have a period of several hours of darkness each day also for optimum growth.
--Damian Hoffman  - from Stickney.