‘Plant eats match’ demonstration

During the 2007/2008 school year, teachers at various schools designed a sealed box for carrying out CO2 experiments. This box is particularly suitable for measuring plant respiration.

Biology teacher Daan Bosma gave the first demonstration with this CO2 box at the Maartenscollege school in May. The box contained petunias. A grow lamp was hung above the box and the CO2 concentration in the box was measured with a Coach meter. The box also contained an ignition mechanism to light a match.

When Daan closed the box, the CO2 concentration was about 1000 ppm (number of parts per million parts). After only half a matchstick was burned up, the concentration increased to more than 2000 ppm. Suddenly there were a lot of nutrients in the air for the plants. In the next quarter of an hour, you could see that the plants consumed the CO2 (photosynthesis), until the concentration had dropped to 250 ppm. At this concentration the plants release the same amount of CO2 as they can consume, prohibiting further growth.