Students, working in groups of 2 – 4, will set up a basic experiment to observe and calculate the seed germination percentage for two different types of seeds. Once the seeds have germinated the students will measure and chart the growth of the different plants and calculate the growth rate of each plant. After an established time frame (two to three weeks), students will harvest some or all of the plants to determine the general biomass that has been produced and compare the two types of plants.
- One or Two Types of Seeds such as corn and sunflower: These seeds are large enough to allow the students to easily manipulate them and easy for the instructor to distribute the same number per student group. If using two different seeds such as corn and sunflower, a follow up study on the difference between Monocots and Eudicot plants can be done. See Appendix for details. NOTE: It is better to do this with two types of seeds so that students can compare germination percentages, growth rates, and biomass.
- Containers for seed growth: Small 2 – 3 oz plastic drinking cups. Each student group should have enough containers for 10 seed of each type (20 containers). Alternatives: Egg cartons, small aluminum loaf pans. Note: if using paper egg cartons, a pan or tray will be needed under each one to hold the excess water that leaks through the carton. As far as plant growth is concerned, paper egg cartons, or paper cups, would work better since they will allow more air to flow to the roots of the plants. If some of the plants are going to be planted after the experiment (if all are not harvested to measure biomass), paper egg cartons and cups can be planted directly into the ground. Note: The extent of this exercise (Space, measurements, etc.) will depend on the number and types of seeds used. Ideally each group of students would have 10 of each type of seed with each seed in its own container. However, planting two seeds in each container can conserve space, or assigning one type of seed to a group and then having the groups share data (Ex: Groups 1, 3, and 5 have corn seeds, while groups 2, 4, and 6 have sunflower seeds.) Alternatively, grass seed can be used as a more cost effective seed source. See Appendix for Grass Seed Methods.
- Potting soil: Standard potting soil mix such as Miracle Grow works very well. The additional variable of soil type could be added to see how the soil affects seed germination and plant growth. See Appendix for details.
- Spray bottles or wash bottles for watering the seeds and plants
- Rulers for measuring growth of plants
- Permanent markers for labeling the containers. Make sure the markers are permanent especially if using paper containers. Otherwise the water will make the ink smudge on the outside of the container. Suggestion: Give each group a separate color of marker so their samples are more easily identified.
- Growing Area: A well lit windowsill or grow lamps (full spectrum bulbs work best). Old aquariums with their lights work very well. If you are using egg cartons for the containers, removing two cells (egg holders) will make the cartons fit into the aquarium. This also makes it easier to retrieve each group’s plants all at once rather than using 10 separate cups.
- Scissors, electronic scales for measuring general biomass: See Appendix for more specific methodology of measuring Total Biomass. If you wish to do a more specific measurement of biomass, the beginning procedure will be different.
Day 1 Student Procedure:
- Obtain materials for the group.
- Label the containers 1 – 10.
- Fill the containers with the same amount of soil. Each container can be completely filled with soil. When the soil is watered it will compact.
- Place the correct type and number of seeds in the soil. Gently push the point of the seed into the soil.
- Place the containers in the growing area.
- Using a spray bottle or wash bottle, wet the soil thoroughly so that it is wet, but not so wet that it looks like a swamp (visible standing water). If there is too much water the seeds can rot.
- Each day, record if the seeds have germinated or not and calculate the percent germination.
- Once a seed has germinated, the height should be recorded each day and recorded. (See Student Handout below for instructions on measuring and calculating data).
- Each container should be watered as necessary. The soil should look and feel damp but not be swampy. As the plants grow, they will need more water.
- Continue this procedure until at least 5 data points are obtained.