Do All Plants Transpire at the Same Rate Under Different Sources of Light?

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Author: Julianne Blair Bochinski


To determine if various species of plants transpire at the same rate under different sources of light.

Materials Needed

  • 12 2-liter plastic soda bottles
  • potting soil (enough to fill 12 soda bottle bottoms)
  • scissors or cutting tool
  • 3 young specimens each of 4 plant species (suggested: jade plant, African violet, ivy, polka dot plant)
  • 3 cups (0.6 liter) water
  • fluorescent lamp
  • household lamp
  • sunlight
  • spatula
  • graduated measuring cup


Three plants of four different species will be placed in the removable bottoms of 12 plastic soda bottles. The removable tops of the soda bottles will be cut to fit within the soda bottle bottoms to form a kind of convertible terrarium. One sample of each plant species will be placed in the presence of all three different light sources: direct sunlight, a fluorescent lamp, and a household lamp, for a period of 6 hours. The amount of transpiration of the plants will then be compared and recorded.


  1. Pull the plastic supporting bottoms from the soda bottles and fill them with potting soil. Then cut the rounded bases from the upper portions of the soda bottles and put them aside.
  2. Transplant the plants into the soda bottle bottoms.
  3. Water each plant with ¼ cup (0.05 liter) of water and fit the soda bottle tops over the plants to create a terrarium (this will allow you to trap and measure the amount of water that the plants transpire). Be sure to place labels on each bottle top to specify the type of plant and the light source to which it will be exposed.
  4. Place each plant species in the presence of all three light sources for 6 hours.
  5. After the light exposure, remove the upper portions of the soda bottles carefully so that the water that has transpired onto them will not roll off. Then remove the water from each container with a spatula and measure with the measuring cup the quantity of water that transpired from each plant
  6. Repeat Steps 4 and 5 several times to obtain more accurate results.

Plants Under Different Light


  1. What amounts of water did each plant transpire under the different light sources?
  2. Did the same plant species transpire equal amounts of water under all three light sources?
  3. Which light source induced the most transpiration?
  4. What outside variables may have influenced your results?
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