Science Project: How Does Salt Affect Seed Germination?
Excellent Junior High Project
This is the research plan my daughter used for her Junior High Project. She won first place at our Regional Contest and competed at State. The reason this simple project did so well is that she was able to explain how important it is for farmers to be able to determine when the salt concentration in soil hurts the germination of plants.
Another child in our family did a variation of this project in 5th grade for her school project, so I know that this experiment also works with younger children, but be sure that your child has at least one to two weeks time for the experimental process.
Salinity and Crops Science
How much teaspoons or portions of teaspoons, of salt dissolved in a cup of water, can be withstood by a 100 germinating radish seeds if 1 tablespoon of the salt water in the cup is added at a time in a Ziplock Bag with a coffee filter to hold the water?
Hypothesis: The more salt in the water, the fewer seeds will germinate. The radish seeds will not germinate at all in a solution with more than 3 teaspoons of salt in 8 oz of water.
Soil With Too Much Salt
- 10 Ziplock Bags
- 1000 radish seeds
- 10 coffee filters
- tap water (tap water is the control)
- distilled water
- table salt
- 10 cups
- 8 oz. measuring cup
Take ten separate cups. Label them A through J. Fill them as follows:
- Solution A: 8 oz. tap water
- Solution B: 8 oz distilled water
- Solution C: 8 oz distilled water with ½ teaspoon of table salt. Stir to dissolve salt.
- Solution D: 8 oz. distilled water with 1 teaspoon of table salt. Stir to dissolve salt.
- Solution E. 8 oz. distilled water with 1 ½ teaspoons of table salt. Stir to dissolve salt.
- Solution F. 8 oz distilled water with 2 teaspoons of table salt. Stir to dissolve.
- Solution G. 8 oz. distilled water with 2 ½ teaspoons of table salt. Stir to dissolve.
- Solution H. 8 oz. distilled water with 3 teaspoons of table salt. Stir to dissolve.
- Solution I: 8 oz. distilled water with 3 ½ teaspoons of table salt. Stir to dissolve.
- Solution J: 8 oz. distilled water with 4 teaspoons of table salt. Stir to dissolve.
2. Place the 10 Ziplock Bags down on the counter at room temperature. Label the top and bottom of each plate with the letter of the solution to be used in each one (A through J).
3. Unzip the bags and put a coffee filter in each one.
4.. Pour one tablespoon of each solution onto the filter in the bag with the same label, making sure it soaks the whole coffee filter.
5. Divide the 1000 seeds into groups of 100. Put 100 seeds on the filter of each Bag. Make sure the seeds are scattered evenly over the filter.
6. Zip up the Bags. Place all 10 dishes at room temperature out of direct sunlight (seeds don't need light to germinate and light can cause fungus to grow).
7. Observe the dishes daily and record number of seeds that have germinated in each dish and any other changes in the seeds.
8. Record results in journal.
Safety: You need goggles for the salt water splashing in your eyes, and gloves so you do not transfer bacteria to the seeds.
How Salt Accumulation Affects Crops
Abstract of Experiment and Results: The problem was to determine the effect of salt water on germinating radish seeds, and also to determine if there was a maximum concentration that could be tolerated.
To do this, coffee filters were wet with 1 tablespoon of salt water from cups that increased in concentration by 1/2 teaspoon of salt in each cup of 8 oz. of water. The filters were then placed in the plastic bags. The 50 seeds were then placed on top of the coffee filters, inside the bag. The seeds that germinated were counted and charted. Tap and distilled water without salt were used as controls.
The results were that the germination was 100% with the controls, tap and distilled water. On the groups exposed to salt water, the germination decreased as the salt concentration increased, and no germination occurred at amounts of 1.5 tsp. of salt or higher. This supported the hypothesis, which was, "The more salt in the water, the fewer seeds will germinate."
This information could help gardeners and farmers to know when saline reaches dangerous levels for radish seeds.
Economic Effects on Agriculture of Salinity in Water in California
Science Fair Experiment Tips
One Thing We Learned: Our first version of the experiment had none of the seeds germinating! So we had to re-do the experiment with less salt in the water. If you have time, it helps to do a pre-test of an experiment.
However, scientists are always honest. If your experiment doesn't work out but you did everything you said you would do, you should still publish your results exactly. What you can put in your conclusion is how you would alter the experiment next time. We had time to re-do our experimental design and try again, which is exactly what my husband does when his experiments don't work the first time!
Variations of Project
Variation using Plants: You can do a variation on this project by watering plants with water with different concentrations of salt to see how salt water affects the growth of plants. As the coordinator of an elementary science fair, I've seen students do lots of plant watering experiments using different kinds of water, but I've never seen a salt experiment.