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Science Fair Project

The Effect of Types of Lights on Plants Purpose: To find out if plants grown under the sun grow better than plants grown under household lights. Hypothesis: The type of light will affect how well slim sweet pepper plants will grow. Based on my research, and my prior knowledge, I believe plants under sunlight will grow the best, then plants under halogen, incandescent, and then black light. Materials:  Fluorescent, incandescent, and black light bulbs (1 each 60 watts)  3 lamps  24 pots  Potting soil  Water  24 sweet slim pepper plants  3 areas where no sunlight can reach the plants Background Information: Slim sweet peppers (Antohi Romanium) Capsicum annuum is a pepper that usually grows about 45-60 cm at full maturity, which can take about 69-80 days. This plant does best in full sun exposure. The pepper that it gives off when fully mature is about 10-15 cm centimeters. It is usually red when ripe, and yellow or green while still maturing. Slim sweet peppers need daily watering, but be careful not to overwater or the plants might die. These peppers are usually used fresh in salsa or salads, but can be used for frying, stuffing, drying, or pickling, depending on what you like. Family: Solanaceae Genus: Capsicum Species: Annuum Common name: Sweet pepper or Slim sweet pepper Procedure: 1. Put the plants inside of the pots and add potting soil and (equal amounts) 2. Divide the plants into 4 groups. 3. For the first group, leave 6 plants in the under an incandescent light (9 cm from the light). 4. For the second group, leave 6 plants under a black light (9 cm from the light). 5. For the third group, leave 6 plants under an halogen light (9 cm from the light). 6. For fourth group, leave 6 plants outside in the sun. Make sure the plants in the sun are not rained on, but still can receive full sunlight so that they do not get extra water. If this is not done correctly, this can affect the results. 7. Make sure the lights do not shine on the other plants except for the ones they are supposed to shine on. All groups except for group 4 should be in dark areas where the sun cannot reach them. This can also affect results. 8. Leave each lamp on for 12 hours per day. 9. Water all the plants equally, every other day. 10. Keep observations for 4 weeks on the height, # of leaves, diameter, and the length of the longest leaf in cm. Variables Independent variable: Type of lights shining on the plants Dependent variable: Slim sweet pepper plants growth Abstract I started with 4 groups of 6 slim sweet pepper plants, and I set each group under a different light. The types of lights I put them under were incandescent, halogen, black, and regular sunlight. The incandescent, halogen, and black light plants all grew slowly at about the same rate. The plants in the sun grew very quickly and were obviously doing much better than the other plants, even though all plants were being watered and exposed to light evenly. The plants under the incandescent light stopped growing in about three weeks. The plants under the halogen light all died (except for the 2 closest to the light) in about 2 weeks. The plants under the black light all died in approximately 2 weeks from the start of the project. Data Analysis The data suggests that plants under sunlight usually grow better than plants grown under artificial light. My observations were that the plants under the other types of lights did not have enough nutrients to grow, but to just stay alive for a few weeks, whereas the plants under the sun had enough to thrive and grow. In the beginning of the experiment, the plants were very alike, with the Standard Deviation under 3.1. This means that all the data was very close together, and that there was not much difference in the plants. The range of height was only 4 cm apart at the most. At the end of the project, all of the Standard Deviation were above 5, and went up to 14.2. Also, the height range went up to 28 cm apart. This tells me that during the experiment, the plants had changed a lot from each other. Conclusion: The data partially supports my hypothesis, which was that the type of light would affect how well slim sweet pepper plants; I thought the plants in the sunlight would grow the best, then the plants under the halogen light, then under the incandescent light, then the black light. The plants the sun grew the best, followed by the plants under an incandescent light, and then the halogen light, and finally black light. The data showed that the plants under the sun grew almost double of the next closest plant group, which was the incandescent light. The plants in the sun grew steadily, and passed all the other plants by far. (The tallest plant in the sun grew 12 cm taller than the next tallest plant under a different light at the end of the experiment. The plant with the most leaves on a plant in the sun had 29 more leaves than the plant with the next most leaves at the end of the experiment, etc.) The plants under the incandescent lights seemed to not grow, just stay the same, but some leaves fell off about three weeks into the experiment. The plants under the halogen light had all been growing at about the same rate as the plants under the incandescent light, but in about two weeks, only the two closest plants to the light were growing, and the others had withered. For the black light, all the plants died within approximately two weeks. Reflection If this experiment were to be done again, I would suggest that the sample size (24) plants, be much larger, to get more accurate results. I would also suggest that the number of trials (1) be increased to get more accurate results, also. Another change I would suggest would be to keep data of the plants longer. My father told be about a light bulb called GrowLight, which is supposed to help plants to grow. If I redid the experiment, I would use this bulb, also. My data suggests that plants in sunlight grow better than plants under incandescent, halogen, and also black lights. I have learned that if I would like to grow plants, I should grow them in regular sunlight, because they should grow better. I could apply what I learned by suggesting that people should grow their plants under sunlight instead of artificial lights. References Black, David, and Anthony Huxley. "Plants," The World Of Science. NewYork, NewYork: Orbs Publishing Limited , ©1995. “Color Matters-Science” SAS University ©2002 Accessed 27 December 2004. http://www.colormatters.com/science_faq.html#Anchor-Is-49575 Detroit, Gale. Encyclopedia of Science, ©1996 ed. Eagle, Gretchen. “Easy Gardening...Peppers” ©1999 Texas A&M University. Accessed 27 December 2004. Gramet, Charles. Light and Sight. Toronto: Abelard-Schuman Company, ©1993. “How does light affect plant growth?” Singapore Science Center ©2002. Accessed 27 December 2004. www.science.edu.sg/ssc/detailed.jsp?artid=1500 Janulewicz, Mike. Plants. Toronto: Gloucester Press, ©1984. Jansten, Sarah. The World of Plants. New York, New York: Gloucestor Press, ©1984 Saling, Travis. “Peppers!” The West Side Gardener ©2004. Accessed 27 December 2004. http://www.westsidegardener.com/articles/19970613Peppers.htm. “Sweet Peppers” Dave’s Garden ©2005 Accessed December 27, 2004. http://davesgarden.com/pf/go/78978/