Green Thumb: The Effect of Temperature On Seed Germination

Lesson Description:    In this investigation the effect of temperature is studied upon various agriculturally important crop seeds. Students propose a hypothesis and test the effect of three different temperatures on germination of a specific seed such as bean, tomato, radish, pea, etc.

 
 

Teacher Notes:  A possible effect of global warming may be its impact upon agricultural outputs and the types and harvests of crops a particular area may be able to sustain. A review of global warming, climate, important agricultural crops in your area and possible local predictions on long-term agricultural outputs may be desired before initiating this study. You may want to have 2 to 3 students work cooperatively as a group or plan for individual study. Student groups can work on one type of seed throughout the study, or compare different varieties e.g., Beefsteak tomato and cherry tomato or several varieties of sweet corn. Seeds should be "in season" and not be stored longer than eight months. Paper towels should be kept moist throughout the study period. Use of a quart size or larger resealable bag will eliminate the need to overly handle the seeds. The seeds can be viewed through the bag. The success of germination can be measured in either total numbers at the end of a two week period, but also in the rate at which seeds germinate i.e., it may take radishes two or three days to complete germination and it may take lettuce five days to germinate.                          As an adaptation to this lab activity you may omit some of the specific procedure instructions, such as equal size of paper towels, and allow students to develop some of the procedure on their own. Allow students to brainstorm what variables are involved in this investigation and which of these variables must remain constant.

 

Students will:
• study the effect of various temperatures on seed germination rate of agriculturally important plants.
• propose a hypothesis comparing the germination rate of seeds in a warm, cool, and room temperature environment.

Time:              One 45 minute class to introduce and set up the study.
                        10 - 15 minutes each day to collect data.
                        One 45 minute class for wrap up and clean up.

Grade Level:  Grades 7 - 12
                         Adaptable for younger students

Materials:      One or more types of crop seeds such as wheat, sweet corn, tomato, various beans, radish, peas, etc.
                        Paper towels-(not napkins)
                        Water
                        Tray
                        Thermometers
                        Quart size resealable plastic bags

The Student Lab

Procedure:

1. Propose a hypothesis regarding the germination of seeds in three different temperatures.
2. Obtain 60 seeds of one type.
3. Obtain three equally sized sheets of paper towels.
4. Prepare a seed germination chamber by folding the paper towel in half.
5. With a pencil (not pen), label the outside of each towel; one at warm, one as cooler, and one as room temperature. Also label each with the name of your group.
6. One the inside of the paper towel folds, place 2 rows of your test seeds (20 seeds total).
7. Place your paper towel chambers on a tray and water them so as to soak the towel, be sure not to overeater. Be sure to check the towel moisture each day and maintain at a moist but not overly moist condition.
8. Keep a record of the number of seeds that have germinated each day as well as taking the temperature of each towel. (Allow 60 seconds for each temperature measurement.)
9. At the end of your study, dispose of the materials as your teacher proscribes.
Analysis:
1. Arrange your data into tables showing dates, temperature, number of germinated seeds, and percentage of germinated seeds.
2. Plot a line graph of number of seeds germinated vs number of days.
3. Was there a difference among your three groups?
4. Which group could be considered the control group? Why?
5. Compare your results with other students who used the same seeds as you did.
6. Write up the experiment according to your teacher's guidance.
7. Evaluate your original hypothesis as it relates to your data.
8. Write a conclusion based upon your data.
9. How did your results compare to those of other groups?
Assessment:
Use the following links to help you develop innovative alternative forms of assessment.

          Concept mapping links:
           1) Lesson in teaching concept maps to students-visual included
           2) More in depth example of a concept map - detailed visual included
           3) Teacher instructions and tips

            Rubrics:
            1)   Teacher Links On Rubrics
            2)   Rubric Information - Advanced Secondary

 
Extension:
1. List  implications for agricultural crops in your area due to an increase or decrease in soil temperatures.
2. Propose an experiment to test the effect of global warming upon an agricultural crop(s).
3. Discuss how a changing agriculture due to global climate change might affect the economics of your area, the USA, or other country.
4. Write a narrative about a farmer's problems in which his/her farm has undergone a change due to warming, cooling, or drying.
5. Explain the relationship between soil temperature and soil moisture.
6. If 20 or more groups used the same seeds, plot a "stem and leaf " to show final germinated numbers. Plot a "box and whiskers" graph to include maximum, minimum, median, and range for all three test groups (cool, warm, and room temperature).
7. Formulate a new hypothesis and design an experiment to test your hypothesis.

Additional Sources:

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Innovations: For Science Classrooms
This site contains ides for teaching environmental studies
www.cpc.gov/publish/innovate.htm

Climate Research Unit: Publications
This site includes a bibliography of recent research on climate
www.cru.uea.ac.uk/cru/pubs/full.htm

Center For Air Pollution Impact and Trend Analysis
This site contains recent data and research from Washington University, St. Louis
http://capita.wustl.edu/CAPITA/

University of Toronto Environmental Research and Teaching
This leads to "Centres" of Environmental Activity
www.utoronto.ca/env/estxt.htm

Global Climate Change and its Impact on World Agriculture
This includes basic facts on the effects of global climate change
http://www.doc.mmu.ac.uk/aric/agricult.html

The Weather Channel Home Page
Useful for maps, forecasts, and breaking weather news
www.weather.com

Woodrow Wilson Leadership Program in Environmental Science lpt@www.woodrow.org
The Woodrow Wilson National Fellowship Foundation webmaster@woodrow.org
CN 5281, Princeton NJ 08543-5281 Tel:(609)452-7007 Fax:(609)452-0066