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UV Radiated Plants

based on 5 ratings
Author: Randall Frost, Ph.D.

Grade Level: 6th - 8th; Type: Life Science

Objective:

This project attempts to determine whether increased levels of ultraviolet radiation are harmful to selected plants.

The goal is to have the student conduct a controlled experiment to evaluate the effect of excess UV radiation on the growth of lettuce plants.

Research Questions:

  • Does excess UV radiation have any negative effects on the growth of lettuce plants?

All plants need ultraviolet radiation to grow, but some researchers have reported that elevated levels of UVB radiation can interfere with plant photosynthesis. Plants that have shown sensitivity to increased levels of UVB radiation have included peas, beans, oats, lettuce, cucumber, and tomato. This is of concern to scientists because ozone depletion in the earth’s atmosphere allows for increased transmission of UVB radiation to the earth’s surface.

Note: At the surface of the earth, ultraviolet radiation from the sun falls mainly into the UVB range (290 to 320 nm) and UVA range (320 to 400 nm).

Materials:

  • 12-in. terrarium; terrarium hood; full spectrum UV fluorescent lamp; lettuce seedlings
  • A terrarium, hood, and UV lamp designed for holding reptiles may be purchased online or at selected pet stores. Lettuce seedlings may be purchased at plant nurseries or grown from seed.

Experimental Procedure:

  1. Read about the positive and negative effects of ultraviolet radiation on plants.
  2. Develop a hypothesis to predict how increased ultraviolet radiation might affect lettuce plant growth.
  3. Purchase six lettuce plant seedlings from a plant nursery or other source. Alternately, grow the plants from seed. Make sure the plants are in containers large enough to accommodate the plants’ future growth.
  4. Place the plants outdoors where they will get adequate sunlight. Keep them watered.
  5. Label two of the containers X1 (for Experiment 1) and two X2 (for Experiment 2). Label the others C (for Control).
  6. In the evening, expose the plants in the X1 and X2 groups to radiation from a UV fluorescent lamp.  Expose the plants in the X1 group to the UVB light for one hour, and the plants in the X2 group for two hours. Return the plants outdoors with those in the control group when you have finished.
  7. Continue this procedure for one month.
  8. Compare the plant characteristics in the three groups after the one-month period. Be alert for differences in leaf size, water use efficiency, and photosynthesis.
  9. Evaluate your hypothesis in light of the results of your experiment. If necessary modify your hypothesis, and propose another experiment to test it. 
Control group
Plant characteristics initially
Plant characteristics after 30 days
Plant 1
 
 
Plant 2
 
 
 
X1 group
Plant characteristics initially
Plant characteristics after 30 days
Plant 3
 
 
Plant 4
 
 
 
X2 group
Plant characteristics initially
Plant characteristics after 30 days
Plant 5
 
 
Plant 6
 
 
 

Terms: UV radiation; Ozone; Photosynthesis

References:

 

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