Science Project: How Does Salt Affect Seed Germination?
Excellent for Junior or Senior High
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. She also won some special awards because she had tackled a real-world problem.
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
The question is what you are going to test. You can do this same experiment in many different ways. You can vary your question by changing:
- The amount of salt in water.
- The number of seeds you use.
- The type of seeds you use.
- How you grow the seeds.
- Where you put the seeds to grow them.
- What you use to grow the seeds on.
Sample question: How much teaspoons or portions of teaspoons, of salt dissolved in a cup of water, can be withstood by 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?
Your hypothesis tells what you think the answer to your question will be. It is your guess. After doing your experiment, you will compare your guess with the results for your conclusion.
Sample 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.
- 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.
in truth, this experiment doesn't really require any particular safety procedures. However, if you are required to put this section on your board, you can include something like the following:
Sample Safety Procedures: 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
As you conduct your experiment, you should record what happens every day on a chart. When your experiment is finished, you will look at the results and write out what happened. You can choose to talk about this in different ways:
- Describe what happened day by day to each bag.
- Describe the overall results and then talk about particularly interesting things that happened.
- Talk about the results for each bag and then compare them.
Sample Table for Results
A: number sprouted
B: number sprouted
C: number sprouted
D: number sprouted
What do you think about your results? In your conclusion, you explain:
- Whether your guess was right or not.
- How your results compare to your hypothesis.
- Your ideas of why your results came out the way they did.
- How you would revise the experiment to make it better.
- What experiment would you do next to get more information?
- The importance of your experiment to real-world problems.
An abstract is a short summary of everything in your experiment. It explains your procedures, your results, and your conclusion briefly. Scientists rely heavily on abstracts when they are researching. They will read the abstract to get an overview of that experiment and decide if they need to read the full article.
Sample 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.
Start early: It is always a good idea to start your experiment early so that you have time to re-do it if you have any problems. Two of my children did versions of this experiment for our state science fair. Maggie, who did the experiment first, found that none of her seeds germinated! Luckily, she had started her experiment early enough that she had to time revise her procedures, adding less salt in the water, and re-do her experiment.
Tell the Whole Story: In her conclusion and results, Maggie wrote the whole story of her experiment, the original failure, and her second try, which is exactly what my husband does when his experiments don't work the first time!
Be honest: Scientists are always honest about their results. If your experiment doesn't work out but you did everything you said you would do, and you don't have time to revise and do it again, you should still publish your results exactly. What you can put in your conclusion is how you would alter the experiment next time.
Plants not seeds: 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, or liquids other than water. but I've never seen a salt experiment.
Different types of seeds: Radish seeds sprout quickly, but many other types of crop seeds could work as well.
Plant the seeds: You could do a longer variation of this project by planting some of the seeds that sprout and continuing to water them with the same salt concentration.
What Grade Level of Science Project are you doing?
Questions & Answers
If the seeds need to be watered, do we have to water with their relative solution? Like if the solution C for Zip Lock bag C is water with 1.5 teaspoons of salt in it, do we have to use that for watering them daily?
Yes. If you need to add water to the bag, you need to use the same solution to ensure that the experiment is the same. You might want to save the solution you make in a sealed container (so it does not evaporate and change the salt concentration) in case you need to do this. However, if you have the bag closed tightly, you will probably not need to add more solution.Helpful 1
What are the variables?
The concentration of saltwater is the variable.Helpful 19
Do you need a lot of seeds to see how salt affects seed germination? Is it okay to use about four seeds in each Ziploc bag?
I would not recommend using only a few seeds for each bag because you will not have enough data for your results. These are very inexpensive seeds. I'm sure we got them for under a dollar. I would suggest using at least fifty per bag.Helpful 13
How often you water the seeds, if at all?
Check each bag every day to make sure that the paper towel or coffee filter is moist but not wet. If you see a lot of water in the bag, it is probably too much water. If you see there is some dryness, then add just enough water (of the appropriate salt concentration) to make it moist again. Each bag will be a little bit different because the number of germinating seeds will change the amount of water needed. Since you need to check the bags daily to count the seeds that have germinated, it is easy to also check each bag to see if it needs more water. Keep your water concentrations in covered containers so that you don't need to make any more of them. The containers need to be covered so that they don't evaporate and cause the salt concentrations to increase.Helpful 10
How does salt affect the growth of a radish seed?
That is a good title for this project. Your experiments will give you the results. Here are the types of things that farmers would be concerned about:
1. Does the seed germinate less quickly?
2. Does mold develop on the seed?
3. Do fewer seeds germinate?
4. Does the sprout die after germination?
5. Does the sprout look stunted?Helpful 10