Sunlight will allow plants to grow faster and taller than UV light. I feel that sunlight will allow a plant to grow faster and more abundantly because it is much more natural and has less artifice than UV lights. UV rays which are known to cause cancer and skin disorders in humans will definitely be harmful to simple plant life.
A student performed this type of experiment using rock cress seeds. He ran the experiment from March 21, 1998 to April 12, 1998. He put 100 each into a plastic cup. One cup was only exposed to sunlight, where the other cup was exposed to sunlight and the UV light. The UV light was about four inches away from this cup. The student initially had the UV light on 24 hours a day up until March 30th when he turned it on and off at sunrise and sunset. The student measured the length of the leaves from both plants and found that the plant growing under the UV light was smaller than the plants growing under the rays of natural sunlight.
Another person performed an experiment using nasturtium seeds. They planted about 18 pots. Nine of them went by a window and the other nine were placed under the UV lamp. The plants were watered everyday and data was recorded every 3-4 days. In this experiment the UV plant was under the UV lamp all day and night, while the control plant was only given light while the sun was shinning. In this instance the UV plant outgrew the contro[->0]lled plant by 5cm.
Experimental Design I chose this experimental plan because I believe it is the easiest method to finding an answer to my hypothesis. It takes little effort on my part initiate the experiment and is easily measurable.
I will first collect all my supplies, which include: 2 cups, UV lamp, 4 red beans, soil, standard 12in ruler, milliliter (ml) beaker, water, measuring cup, and a permanent marker. I will then name and label my plants. Michael will be the plant that only gets natural sunlight. Abigail will be the plant that only receives UV light. I will write the names on each cup using the permanent marker. After labeling them, using the measuring cup, I will scoop out 2 cups of soil and put it in each cup. Then I will dig two small, but deep holes in the soil of each cup. I will place a red bean in each hole and cover them up with the soil. Then, using the ml beaker, I will pour 2ml of water into each cup. I will place Michael on a windowsill to get the maximum exposure to the sun. I will move Abigail away from any direct sunlight and place her under the rays of the UV lamp. Everyday I will give the plant 2ml of water. When the sun goes down I will turn off the UV lamp to guarantee that both plants receive the same amount of light. Every two days I will document any progress or lack of progress. Once the plants begin to sprout I will begin to use the 12in ruler to measure the growth of the plants and document it.
Independent, Dependent, and Controlled Variable My independent variable will be the UV light and the natural sunlight. The dependent variable will be the plant growth or the length of each plant. Finally the controlled variable would be the red beans, the amount of water given to each plant, the type of soil each plant used, as well as the amount of sunlight or UV light each plant receives.
Threat Reduction to Internal Validity To reduce any contamination or threat to my findings, I will make sure each plant has the same control variables. Both plants will have beans from the same brand and packaging. They