Introduction This experiment explores the effect of light color on chlorophyll levels in Wisconsin Fast Plant leaves. The rationale of this project is

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1 Maylin, Victoria, Sam, Prahlad The Effect of Light Color on Chlorophyll Levels in Wisconsin Fast Plant Leaves 11/20/2015 Teacher: Mr. Roche Mentor: Mr. Schultz

2 Introduction This experiment explores the effect of light color on chlorophyll levels in Wisconsin Fast Plant leaves. The rationale of this project is to increase plant growth efficiency (chlorophyll level) for people growing plants. For example, this information could be used when choosing which color LEDs to grow plants under when artificial lighting is needed, such as in space. We previously knew that some pigments in plants absorbed light energy best at certain wavelengths. According to many online sources, including Wisconsin Fast Plants Program and other researchers who have worked with this species, Brassica rapa are extremely versatile in growing conditions. In our experiment, we will be placing Brassica rapa under different colors of light and measuring the amount of chlorophyll produced by the leaves of the different plants. The assumption is that no one touched the experiment while it was in progress. We will measure the amount of chlorophyll in plants by using an RGB tool to calculate the level of greenness of each of the leaves. Chlorophyll reflects green light ( Arizona State University ), so the more chlorophyll, the more green light reflected. This will allow us to determine how different colors of lights affect the efficiency of chlorophyll production. Based on prior knowledge and research, we believe that different colors of lights will affect the amount of chlorophyll produced in Wisconsin Fast Plant leaves. Hypothesis Alternate Different colors of light will affect the amount of chlorophyll in Wisconsin Fast Plant leaves. Null There will be no significant difference in the amount of chlorophyll in Wisconsin Fast Plant leaves based on the color of light.

3 Methodology Materials List Amount Material Source 30 Wisconsin Fast Plant Seeds (F2 Non-purple stem Yellow-green Leaf) HTHS 2 Gatorade Bottles Worth Water HTHS 4 Gatorade bottles HTHS 1 Seed Starter Potting Soil HTHS 1 Fluorescent Lamp HTHS 1 cyan, 1 yellow, 1 magenta Plastic light filters HTHS 4 Fabric wicks HTHS 1 8 foot pipe (divided into 4 2-foot sections) All members 10 3-inch pipes (thinner than the 8 foot pipe) HTHS Equipment List Equipment Computer Vernier Light Intensity Sensor X-Acto Knife Handsaw Dremel Camera Source HTHS HTHS HTHS HTHS Sam Victoria Facility High Technology High School research laboratory

4 Experimental Design Diagram Independent Variable Light color, changed using a version of light filters (plastic discs) Dependent Variable Amount of chlorophyll produced (measured via color of leaves; take a photo and then use GIMP to calculate the greenness) Color of Light Cyan Yellow Magenta White Number of Trials Control? Control Operational Variable The average green values of the leaves, measured by taking a photo and using GIMP s color picker tool. Constants: Room Temperature (70-72 degrees Fahrenheit) Organism Species (Wisconsin Fast Plants, or Brassica rapa ) Soil Type (Seed Starter Potting Soil) Population Density (6 plants per bottle) Light Intensity (using a light intensity measurement tool, the light intensities can be maintained by moving lights towards or away from the plants.) Watering frequency (via water reservoir) Time (plant has 2 weeks to grow before measurements are taken)

5 Setup, Graphics, Illustrations Figure 1: The final setup, where the plants are inside the gatorade bottles inside the pipes. Figure 2: A closeup of our planting apparatus. Figure 3: Two photos of some of the germinated plants.

6 Procedure 1. Gather all listed materials. 2. Hang a lamp above the area in which the plants will be planted. 3. Cut off tops of gatorade bottles and place tops upside-down onto bottoms. 4. Fill bottoms with water. 5. Build fabric ribbon wicks. 6. Fill gatorade tops with potting soil. 7. Plant seeds two centimeters deep. 8. Cut 4 2-feet tall sections of the pipe. 9. Use a Vernier Light Intensity Sensor to measure the intensity at the bottom of one pipe (this pipe will not be filtered). 10. Take one of the color filters, put it over the light, and measure the distance using the light sensor to find the same intensity as the white light. 11. Repeat step 10 for the other colors. 12. Cut 4 different pipes to match the distances (use the thinner pipes). Tape together pipes if necessary. 13. Put the thinner pipes inside the larger pipes under the lamps. 14. Ensure that all plants receive the same light intensity by placing them at appropriate these heights according to the above measurements. 15. Place the bottles inside of the pipes. 16. Planting is finished. 17. Check every so often to ensure that no unexpected events occur. 18. After twenty days of growth, remove the twelve highest leaves. 19. Separate the leaves based on the color of light they received. 20. Take a photo of the leaves with a camera (be careful not to change lighting, filter, etc). 21. Open GIMP. 22. Open the photos taken. 23. Use the RGB tool to determine the green values of each leaf. 24. Analyze the results.

7 Data Figure 4: A photo of the leaves, sorted into cyan, yellow, magenta, and control Final Measurements Table 1: Green Values of Leaves Under Different Color Lights Cyan Yellow Magenta White (Control) Leaf Leaf Leaf Leaf Leaf Leaf Leaf Leaf Leaf Leaf Leaf Leaf

8 Table 2: Summative Data Table for Green Values of Leaves Under Different Color Lights Cyan Yellow Magenta White (Control) Average Standard Dev n Figure 5: Graph of average green values of leaves under different color lights Findings This data supports our alternate hypothesis. The program we used, GIMP, provides higher numbers when the green is brighter/lighter, and lower numbers when the green is darker. Therefore, the higher greens contain less chlorophyll than the darker greens. As shown in the graph, leaves under cyan light had the highest number, and therefore produced the least chlorophyll. A possibility is that when the plants receive more energy from light, they do not need to produce as much chlorophyll, because it would be a waste of resources. Chlorophyll b, as shown by Dr. Ross E. Koning, absorbs more cyan than any other color. Leaves under white light came in second-to-last, most likely because it includes all of the wavelengths a plant can absorb ( Ask a Biologist ). Magenta and yellow received the lowest numbers and therefore had the most chlorophyll, because the plants need more chlorophyll to get the energy from these colors. The results of this study show that plants are able to increase or decrease the amount of chlorophyll they produce, and that they will do so depending on circumstance. They will decrease their chlorophyll levels when chlorophyll isn t needed as much and increase it when more energy is needed.

9 Suggestions for Further Study This study shows that plants change their chlorophyll amount, but it doesn't say anything about other pigments. Another experiment could test how much of every pigment is present, possibly through chromatography. Another suggestion for another study might be to measure chlorophyll produced for light outside of the visible spectrum. Those might offer energy to plants as well. One final study suggestion is to explore the effects of the amount of nutrients on a plant s chlorophyll production. The researcher could compare different levels of phosphorus, potassium, and nitrogen. He/she could also test the effect of different fertilizers to see which fertilizer is most effective.

10 Works Cited Baufer, Heidi Laxter, PhD. "The Wisconsin Fast Plants Program." The Wisconsin Fast Plants Program. JESS, Web. 16 Nov < >. "BRASSICA." BRASSICA. University of California. Web. 16 Nov < >. "Chlorophyll Causes of Color." Chlorophyll - Causes of Color. Web. 19 Nov < >. Driblette, Randolph. "Facts About Wisconsin Fast Plants." EHow. Demand Media. Web. 16 Nov < > "Growth & Development." Wisconsin Fast Plants Program. Web. 16 Nov < >. "HISTORY." Wisconsin Fast Plants Program. University of Wisconsin - Madison, Web. 16 Nov < >. Koning, Ross E. "Light." Light. Web. 19 Nov < >. "Plants in Space: Wisconsin Seeds First To Sprout From Stock Grown on Mir." Plants in Space: Wisconsin Seeds First To Sprout From Stock Grown on Mir. University of Wisconsin - Madison News, 10 Sept Web. 16 Nov < >. "RECYCLED BOTTLE PROGRAM." Wisconsin Fast Plants Program. Web. 16 Nov < >. "School of Life Sciences Ask A Biologist." Chlorophyll and Chloroplasts. Web. 19 Nov < >. Wisconsin Fast Plants: Beginning the Cycle.: STC/MS, PDF. < o/pdfs/lesson_5.pdf >.