The Effects of Light and Temperature on the Growth and Development of Plants 

Robinson, Minnie L. Fenger High School
11220 South Wallace Ave.
Chicago, IL 60628

Objectives 1. To show how visible light constitutes only a small part of the spectrum of radiant energy. 2. To show how light can be separated into a variety of colors if passed through a prism. 3. To show that certain colors correspond to different wavelengths of the light present. 4. To show how certain wavelengths are reflected by plant pigments and others are absorbed. 5. To show that when plants are grown in different wavelengths and temperature variations,the size,color and the length of their growth processes are affected. Equipment and Materials overhead projector vermiculite Early Scarlet Radish Seeds plant food two thermometers water 12 mini peat plant pots two quart bottles two trays or containers graph paper labels small metric ruler Polaroid Camera green and red transparency paper 12 medium peat plant pots clear transparency sheets Recommended Strategies Review light waves using a prism. Show how light waves can be separated with a prism. Show the different colored light waves. Show how some of the colors can be reflected and others can be absorbed. Encourage students to list the size, color, height, number of leaves, etc., from plant samples given. Using five groups of students, distribute two samples of experimental plant samples to each group. Also, distribute data sheets to each group. Students will observe and record observations. Plot the temperature and growth patterns on a graph. Procedure for growing radish plants: Obtain 12 mini peat pots. Fill each pot to the halfway mark with vermiculite. Plant 10 radish seeds in each pot. Cover them with a thin layer of vermiculite. Water them thoroughly, using a diluted solution of plant food. Use red and green transparencies to cover two pots with red and two pots with green. Use different shades of green and red transparencies to cover one with red and one with green. Place three uncovered plants with the plants covered with the colored transparencies in the sunlight. Observe and record data on a daily basis. Place three uncovered pots in a dark room. Observe and record data daily. Record data on the length, size, color, number of leaves and temperature for each experimental plant sample. Please note: Each experimental plant sample received a normal day without any manipulation of temperature. After 10 to 15 days of observation and recording data, place two of the plants covered with red transparency (plants grown in sunlight) in the darkness. Repeat the above procedure using plants covered with green transparency and plants not covered. Place two of the plants grown in a dark room in a sunlit environment. Observe and record data daily. Record data on the length, size, color, temperature and number of leaves for each experimental plant sample. Use photographs taken with a polaroid camera to show stages of development. Use graphs and charts to plot and make an analysis of the growth processes of plants' responses to visible light wavelengths in relationship to the temperature. Summary Plants usually respond to light, touch and temperature. They respond with leaves, flowers and fruit. Visible light can be separated into different colors. Some colors reflect light while others absorb light. A difference in light wavelengths will significantly affect the length, color, germination period, number of leaves, quality and quantity of fruit. Darker shades of green and red transparency sheets produced a significant degree of change in plant development compared to lighter shades of red and green. Temperature differences were slight and not controlled. All plants received a normal temperature during the experiment. Note: all plants grown in the light received a full day of sunlight. All plants grown in a dark room received a full day of darkness. All plants were watered at the same time using the same amounts of water from the diluted plant food. All data was recorded at the same intervals.
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