Carbon Dioxide, Plant Growth, and the Greenhouse Effect

Medium

What happens to a plant growing in air with extra carbon dioxide? CO2 is not a pollutant, but it traps heat. Scientists call this the greenhouse effect. Rising CO2 levels could change how crops grow worldwide. You germinate seeds in two peat cups with potting soil. One cup sits next to a dish of baking soda and vinegar. Mixing these two substances produces CO2. You cover both setups with large soda bottles and place them in a well-lit area. Only one bottle contains the CO2 source. The other is the control. Each day for five days you record plant growth and temperature inside each bottle. You also note any visible water vapor. Comparing the two setups shows how extra CO2 affects growth and temperature.

Hypothesis

The hypothesis is that increased carbon dioxide levels will have a positive effect on plant growth.

Science Concepts Learned

Plant Growth

Does extra carbon dioxide help plants grow faster? This project tests that question directly. You germinate seeds in two covered setups — one gets extra CO2 from baking soda and vinegar, the other stays with normal air as a control. After five days of measuring, you can see whether added CO2 actually changes how plants grow.

Control Experiment

What happens to a plant growing in air with extra carbon dioxide? To find out, you germinate seeds in two peat cups with potting soil, then cover each with a large soda bottle placed in a well-lit area. One bottle contains a dish of baking soda and vinegar, a mix that produces CO2. The other has no CO2 source at all, making it the control. Both setups get the same light and soil. Each day for five days you record plant growth and temperature inside each bottle, along with any visible water vapor. Comparing the two tells you how extra CO2 affects growth and temperature, because every other condition is identical.

Method & Materials

You will germinate seeds in moist potting soil, create a chemical reaction to produce carbon dioxide, monitor the progress of the plant growth, water vapor, and temperature for one week, and compare the effects of CO2 to the control group.

You will need two large soda bottles with the top removed, two peat cups, a small cup or dish, several crop seeds, potting soil, 10 grams of baking soda, 20 ml of vinegar, and a thermometer.

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Results

The experiment showed that increased carbon dioxide levels had a positive effect on plant growth. The most notable observation was that the plants in the CO2 system grew faster than the plants in the control group.

Why do this project?

This science project is interesting and unique because it shows how increased carbon dioxide levels can affect plant growth, and how this can contribute to global warming.

Also Consider

Consider experimenting with Elodea in a closed system such as a soda bottle with water. Try blowing into the container through a straw and compare the results to a sealed system.