Harmful or Helpful? The Effects of Hydrogen Peroxide on the Roots of Plant Cuttings & on Seed Germination
AbstractHydrogen peroxide (often used as a disinfectant) has also been approved for use in pesticides. This science fair project investigates whether hydrogen peroxide has any effects on seed germination or on roots of plant cuttings.
Sandra Slutz, PhD, Science Buddies
The purpose of this science fair project is to find out the effect of different concentrations of hydrogen peroxide (H2O2) on the roots of plant cuttings, and on seed germination.
Hydrogen peroxide (H₂O₂) is known as a common disinfectant; however, the Environmental Protection Agency (EPA) has also approved the use of hydrogen peroxide as an ingredient in pesticides. The EPA has deemed hydrogen peroxide safe for use on non-food and food crops, both before and after harvest, because it is an effective algicide and fungicide at low concentrations. It also breaks down quickly and safely in the environment, into water (H2O) and molecular oxygen (O₂), as shown in Equation 1.
|2 molecules of hydrogen peroxide||→||2 molecules of water + 1 molecule of oxygen|
|2 H₂O₂||→||2 H₂O + O₂|
Algae and fungus can often attack not just leaves and stems, but also roots, and even seeds. Agricultural scientists are always searching for safe compounds to use on seeds and roots to protect them from pests. In this science fair project, you will investigate whether or not hydrogen peroxide is also safe for use on the roots of plant cuttings, and on seeds during germination. Watch this time-lapse video to see seeds germinating.
Terms and Concepts
- Hydrogen peroxide (H₂O₂)
- Plant cuttings
- What environmental conditions induce germination?
- How do the roots of plant cuttings grow?
- How does hydrogen peroxide work as a pesticide?
- Why is hydrogen peroxide also an effective algicide and fungicide?
A very basic introduction to seed germination:
- Kennell, H. (n.d.). Gardening in Western Washington: Seed Germination. Retrieved December 8, 2008.
A more-advanced explanation of root systems and how they work, using corn as an example:
- Mengel, D. (1995, May). Roots, Growth and Nutrient Uptake. Purdue University, Department of Agronomy. Retrieved March 8, 2012.
Information on hydrogen peroxide:
- Altland, J. (n.d.). Postmergence Liverwort Control in Greenhouse and Nursery Crops. Oregon State University. Retrieved March 9, 2012.
- United States Environmental Protection Agency. (2002, January 30). Hydrogen peroxide (Hydrogen dioxide) (000595) Fact Sheet. Retrieved December 8, 2008.
Visit these websites for information on how to cut and grow plant cuttings:
- Gowdy, M.A. (2002, September). Home Propagation of Houseplants. University of Missouri extension. Retrieved December 8, 2008.
- Howdy, M.A., Starbuck C.J. (2003). Growing Garden and Landscape Plants from Cuttings at Home. Retrieved December 8, 2008.
- Perry, L. (2003, May). Rooting Cuttings. University of Vermont Extension: Department of Plant and Soil Science. Retrieved December 8, 2008.
- Hangarter, R. (n.d.). Corn Germination. Plants-In-Motion. Retrieved February 28, 2012.
Materials and Equipment
Materials for Both Experiments
- Hydrogen peroxide, H₂O₂ (1 32-oz. bottle, or 2 16-oz. bottles). Use a 3% hydrogen peroxide solution, which is the typical concentration found at drug stores.
- Lab notebook
- Graph paper
- Permanent marker
- Masking tape (1 roll)
- Paper towels (1 roll)
Materials for Seed Experimentation
- Graduated cylinder, 250-mL; available at science supply stores, such as Carolina Biological: www.carolina.com product #721614 or a teaspoon measuring spoon and measuring cup
- Bowls (4)
- Sealable sandwich baggies (4 for each type of seed you are testing)
- Seeds from a crop, such as mung beans, broccoli, bok choy, black-eyed beans, garbanzo beans. You can choose how many types of crops you want to test (it is OK to test just one), but you'll need a total of 40 seeds for each type of crop you test.
Materials for Plant Cutting Roots Experimentation
- Cuttings from one or more varieties of houseplants, such as jade, ivy, coleus, donkey-tail, etc. You can choose how many varieties of plants you want to test (it is OK to test just one), but you'll need a total of 12 cuttings per plant variety you test. Note: Do not make the cuttings until you are ready to pot them. See the Experimental Procedure, below, for more details.
- Plant containers
- Make sure all containers are waterproof.
- If you use containers that are at least 5-6 inches wide, you can plant 3 cuttings in each one, so you will only need 4 containers per type of plant you want to test.
- If you have smaller containers, you'll need to plant each cutting in its own container; a total of 12 containers per type of plant you want to test.
- Coarse sand; available at garden supply stores and often called horticultural sand. Note: Do not use fine sand like art or playground sand; only coarse sand will allow enough oxygen to reach the plant cuttings' roots. Buy enough sand to fill all of your containers; the exact quantity depends on the number and size of the containers you will use.
- Hydrogen peroxide, H₂O₂ (1 bottle). Use a 3% hydrogen peroxide solution, which is the typical concentration found at drug stores.
- Oven-proof container, like a casserole dish or baking pan
- Oven mitts
- Knife (to make cuttings)
- Butter knife, skewer, or similar object
- Sealable plastic baggies, size and number depends on the size and number of containers you selected
- Rubber bands, number depends on the number of the containers you will use
- Pen or pencil
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Carefully read through this Experimental Procedure before beginning. You can run both tests at the same time, so you do not need to finish the seed germination test before you begin the plant cuttings' roots test.
Testing the Seeds
- Use the 250-mL graduated cylinder to make four batches of growing solution. If you don't have a graduated cylinder, you can use a 1-cup measuring cup (250-mL) and a teaspoon measuring spoon (5-mL). Pour each solution into a bowl once it is mixed. Each growing solution will have a different concentration of hydrogen peroxide:
- No hydrogen peroxide: 250 mL (1 cup) of water
- Low hydrogen peroxide: 5 mL (1 tsp.) of hydrogen peroxide, 250 mL of water
- Medium hydrogen peroxide: 15 mL (3 tsp.) of hydrogen peroxide, 250 mL of water
- High hydrogen peroxide: 30 mL (5 tsp.) of hydrogen peroxide, 250 mL of water
- With a permanent marker, label sandwich baggies with the name of the seeds you're germinating, and the growing solution. There should be a total of four bags (representing each different growing solution) for each type of seed: none, low, medium, and high hydrogen peroxide growing solution.
- In each plastic baggie, fold a paper towel or paper napkin so that it lies flatly inside the bag.
Figure 1. Arrange the moistened paper towel and seeds in the plastic baggie as shown above.
- Spoon in the type of growing solution labeled on the outside of the bag, until the paper towel inside is evenly moist, but not dripping wet.
- Place 10 seeds in a row across the paper towel inside each bag. Make sure the seed type matches what is labeled on the outside of the baggie.
- Make sure all the baggies are properly sealed.
- Spread the baggies on a table, counter, or other surface, indoors where they can get sunlight.
- Check on the bags daily for 10 days and record in a data table in your lab notebook how many seeds have germinated in each bag. Record all observations in your lab notebook.
- Make graphs showing the percentage of seeds that germinated and the average time to germination for each type of plant in each growing solution. Did hydrogen peroxide concentration affect seed germination?
Testing the Plant Cuttings' Roots
- Get the containers for your cuttings ready by washing them with soap and water. Then wipe the inside of each container with a paper towel soaked in rubbing alcohol to sterilize the container.
- Using masking tape and a permanent marker, label each container with the type of plant and type of growing solution you'll be putting in there.
- Make four batches of growing solution, one at a time, and each with a different concentration of hydrogen peroxide. The exact quantity of the growing solutions you'll need depends on the size and number of containers you're using. Make as many liters of growing solution as you need by doubling, tripling, etc. these recipes:
- No hydrogen peroxide: 1 liter (L) of water
- Low hydrogen peroxide: 20 mL (4 tsp.) of hydrogen peroxide in 1 L of water
- Medium hydrogen peroxide: 60 mL (12 tsp.) of hydrogen peroxide in 1 L of water
- High hydrogen peroxide: 100 mL (20 tsp.) of hydrogen peroxide in 1 L of water
- Sterilize any tools you'll be using to move the sand or to cut the plants by wiping them with paper towels soaked in rubbing alcohol.
- Sterilize the sand by placing it in an oven-proof container (like a casserole dish or baking pan) and heating it in the oven at 200°F for 30 minutes.
- Make sure the sand is coarse. The sand particles must be large enough so that there is room in between the sand grains for air to penetrate and bring the growing plant roots oxygen.
- Allow the sand to cool completely, then fill each container ¾ of the way full with the sand.
- Make your first cutting and then immediately follow steps 7–9. In total, you'll need at least 12 cuttings (3 or more replicates for each of the growing solutions) of each plant type you want to test, but do not make all the cuttings at once, or they will dry out and might not grow well. How to make each cutting depends on the type of plant from which you are cutting. Visit the websites listed in the Bibliography, above, for more information.
- Immediately after making each cutting, place it 1-2 inches deep in the sand, depending on the length of the cutting. You can use a sterilized (with rubbing alcohol) skewer, butter knife, or other such tool to create a hole for the cutting.
- Press the sand firmly, but gently, around the base of the cutting. Add enough of the growing solution to moisten the sand. Note exactly how much growing solution you used and add the same quantity of growing solution to all subsequent cuttings. Record the amount in your lab notebook.
- To prevent the cutting from drying out, place a clear plastic baggie over the cutting and container. Secure the open end of the plastic bag to the sides of the container using a rubber band.
- Repeat steps 6–9 for each cutting.
- Place all of the plastic-tented cutting containers in an indoor location where they get only indirect sunlight. If they get direct sunlight, too much heat might build up in the plastic tenting and kill the cutting.
- Make sure all the containers are in the same location.
- Check the condition of the cuttings, daily, for 18 days. Each day:
- Open each plastic tenting for a few minutes to allow fresh air in.
- While the plastic is open, check the moisture level of the sand. Add more of the appropriate growing solution if the sand appears to be getting dry. Do not let the cuttings dry out!
- Record what the part of the cutting that is above the sand looks like in a data table in your lab notebook. Include drawings if you'd like.
- Re-secure the plastic tenting.
- On the 18th day, insert a butter knife underneath the sand to gently lift up each cutting and examine the roots. Note all your observations in your lab notebook.
- Place each cutting, with its roots, on a piece of paper. With a pen or pencil, trace the roots on the paper. Using a ruler, measure each of the tracings and calculate total root length for each plant. Keep track of the data in a data table in your lab notebook.
- You may also want to try one of the other measurement options from the Science Buddies Measuring Plant Growth guide.
- Create graphs illustrating your data. Did the concentration of hydrogen peroxide have an effect on the quantity of root growth? What about the visual appearances of the roots?
Ask an Expert
- What concentration of hydrogen peroxide is toxic to plants? Is the same concentration toxic for both cuttings and seeds?
- Do seeds and roots of different varieties of plants respond differently to hydrogen peroxide? Try the above experiment with a variety of seed types or plant cuttings to find out.
If you like this project, you might enjoy exploring these related careers:
- Science Fair Project Guide
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- Measuring Plant Growth