Colored Light and Photosynthesis

• White light contains a combination of colors that we call a spectrum. Do plants, however, use all of the colors for photosynthesis? Do some colors of light aid photosynthesis more than others? Use a red, green, blue and yellow marker to color different sheets of transparency film into solid colors of red, green, blue and yellow. Once colored, form the sheets into small "leaf sleeves" so that you have three sleeves for each color. Place the sleeves on leaves of a common houseplant and put the plant near a source of sunlight. Rotate the plant each day. At the end of the week, remove the sleeves from the leaves and make notes about the leaves. Did some leaves grow faster than others? Did some begin to wilt? Did some behave the same as leaves that were not covered at all? How do these changes relate to the color of the sleeve?
  
  

Different Light Sources

• We know plants require light for photosynthesis, but does the light source matter? Using three plants of the same type and size, place one in natural sunlight, one in a room with an incandescent light and one in a room with a fluorescent light. Keep them all on the same watering schedule and be sure to turn the lights on and off with the sunrise and sunset to ensure that all the plants receive the same amount of water and light. After two weeks, record the results. Did one plant grow noticeably faster than the others? If so, by how much? Did one plant fail to grow at the same rate as the others? If so, which one? Are there differences other than growth rate, such as yellowing or browning of leaves?
  
  

Sunlight and Sprouting Seeds

• Plants need light for photosynthesis, but what about seeds? Take three flower pots with soil and plant three bean seeds in each pot. Place one pot in a sunny location for two weeks. Place one pot in sunlight for two hours a day and cover it with a paper bag the remainder of the time. Cover the third pot with a paper bag at all times. After two weeks, record the results. Which seeds sprouted first? Which plants from sprouted seeds grew into plants the fastest?
  
  

The Minimum Amount of Light Needed for Plant Growth

• How much exposure to light is optimal for plant growth? To test how much light is optimal, place potting soil and corn seeds in three pots. Ensuring that they each get the same amount of water, expose one plant to four hours of light per day, expose the second plant to eight hours of light per day and expose the third plant to 12 hours of light per day. Every week, record how much each plant has grown. Document the growth of each plant over the course of a month. How much exposure to light led to the optimum plant growth?