Essay: How Does Carbon Dioxide Affect Plant Growth

In this experiment, I will determine How Does Carbon Dioxide Affect Plant Growth using sunflower seeds and 2- liter bottles to create home-made Carbon Dioxide. I hypothesize that if the amount of Carbon Dioxide is increased, then the plants will grow more because plants require chemicals to grow, therefor causing the amount of photosynthesis to increase causing plants to grow. Carbon Dioxide is a chemical compound composed of two oxygen atoms linked to a carbon atom by a covalent bond . Carbon Dioxide is produced by both natural and human sources. Examples of natural sources that produce Carbon Dioxide include; decomposition, respiration, and ocean acidification. Examples of human sources include; cement production, deforestation, coal, oil and natural gasses. Plants acquire Carbon Dioxide through a process known as Photosynthesis. Photosynthesis is the process of taking in the carbon dioxide produced by all living and breathing organisms which reintroduces oxygen into our atmosphere (Science and Technology Concepts Middle School, 2017). The primary function of Photosynthesis is to convert sunlight to energy to produce glucose (a sugar), which can be converted into chemicals required for plant growth (cellulose), converted into starch, and into a storage molecule (Cook, 2013). Glucose requires Carbon Dioxide, and without it plants would not be able to produce energy from the sun (Reiny, 2016). A study done by Scientist Randall Donohue, of the Commonwealth Scientific and Industrial Organization in Australia conducted a study in which they tested whether plant growth would be more vigorous by increasing the carbon dioxide intake of plants. This is called the Co2 fertilization effect, which states the more carbon dioxide in the atmosphere has resulted in rising anthropogenic emissions should help the plants grow taller, which means increasing carbon dioxide during photosynthesis (Radford, 2009). The study concluded that “Even if nothing else in the climate changes as global CO2 levels rise, we will still see significant environmental changes because of the CO2 fertilization effect,” says Dr. Donohue. Robert Mendelssohn from the Yale School of Forestry and Environmental Sciences suggests that Global Warming can be seen as an advantage for agriculture (Radford,2009). Mendelssohn conducted studies that suggested Global Warming can improve agriculture in some high latitude regions (Radford, 2009). Global Warming is the gradual increase in the temperature of Earth’s atmosphere due to the greenhouse effect, which is caused by increased levels of carbon dioxide and other pollutants (Pappas, 2017). Global Warming is caused by increased carbon dioxide into the environment therefor, Mendelssohn agrees that higher levels of carbon dioxide attribute to a change in plant growth. A recent study from the University of California concluded that an increased atmospheric Co2 created a 30% growth in plant photosynthesis during the last two centuries (Watts,2017). Therefore, carbon dioxide is very prevalent on Earth and may be helpful to plant’s health in growing. The independent variable in this experiment is the Carbon Dioxide and the dependent variable is the growth of the plant. To complete this experiment I used, 1 2-liter bottle, 1 1-liter bottle, an xacto knife or sharp cutting utensil, sugar, yeast, airline tubing, and water.  I started by germinating one package of six sunflower seeds into a biodegradable peat cup with a handful of moist soil and label it A, then complete this step again but label the next pot B (the control). When you germinate the seeds, you must let them sprout which takes about 7- 10 days prior. Germinate means to allow the plant to grow/ sprout. Next, take an empty, clean 2-liter soda bottle and carve a hole with an xacto knife with a diameter of 1.5 centimeters. Then, take an empty, clean 1- liter bottle and carve two small holes with an xacto knife about 1.25 centimeters in diameter. Next, take airline tubing (generally used for aquariums) around 4 feet long and shape it into a U shape. On one end, place the tube through the 2- liter bottle cap hole and on the other end you will connect it to the 1-liter bottle cap hole so it is touching the bottom of both bottles. The 1 –liter bottle needs to be filled up halfway with water and connects to the 2- liter bottle which contains water, yeast and sugar. Then, take an 8 – foot long airline tube and push it into the second hole of the 1- liter bottle just above the water. Place the tube connected to the 1-liter bottle with the other side of the tube hanging out into the soil of the peat cup labeled A. It should be 4 inches down in the soil of pot A. The tubing is very important as it is what transfers the carbon dioxide from the 2-liter to the l-liter, and then from the 1- liter to the plant. Place a thermometer inside pot A. Next, place the pot labeled B (the control) at least 50 feet away from the system. Place a thermometer inside pot B. Keep both pots in the same amount of sunlight and water 3.81 millimeters once every 2 days. Monitor the progress of plant growth and temperature for both pots for 2 weeks and observe the results.