How does road salt impact the germination of seeds?
Salt is used to melt snow and ice on roads and sidewalks. This reduces injury and accidents. Keeping the roads and sidewalks free from slippery ice is generally considered a good thing. On the other hand the salt doesn’t go away at the end of the winter. It stays in the environment. Some of the salt stays in the soil and some of it enters streams, rivers, and lakes with the melting snow and rain. Organisms living in the ocean have evolved to tolerate salt but other organisms do not have adaptations for living in a salty environment. People are starting to study how the salt in our environment impacts ecosystems.
The germination of seeds might be affected by salt in the environment. If seeds are more or less likely to germinate in a salty environment there may be impacts on other organisms that rely on the plants as well. Seeds need specific environmental conditions to germinate. A seed can sit for years and only start to grow, or germinate, when the moisture level changes for example.
Your goal for this project is to design an experiment that tests an environmental condition that impacts a seed germination. You’ll have to think carefully about variables and you’ll want to make sure you have multiple seeds in each group. Some helpful information is included below to help you out as you begin this interesting investigation.
- There is an easy way to get seeds to germinate that we can use for experiments. I found a good way to set up seeds without soil to get them to germinate. All you need to do is fold a paper towel in half and then fold it in half again to make a pocket. Put four seeds inside of the paper towel and then place it in a plastic bag.
- To make things easy we will use chia, bean, and radish seeds.
- Under ideal conditions, radish seeds will germinate within three to four days, but may take as many as 10 days.
Key things to review:
Hypothesis = The possible answers to the question you are investigating
Dependent Variable = The variable that you are measuring changes in. In our case the dependent variable is whether or not the seeds germinate
Independent Variable = The variable that you have set up to see the effects of. We want to see the effects of salinity.
Control Group = This is the group that will be normal. In this experiment seeds without salt will be our control group.
- 20 plastic cups
- 10 zip lock bags
- potting soil
- 20 paper towels
- chia seeds, bean seeds, radish seeds
Step 1: Experimental Design
Directions: Design a high quality experiment to explore how salt impacts seed germination.
|Experimental Design Guide|
|What is the experimental question?|
|What is your hypothesis and why do you think that?|
|What is your dependent variable?|
|What is your independent variable?|
This chart will help you design your experiment. You might want to set up more than one experimental group, like low, medium, and high amounts of salt.
In the final box you will need to draw what each experimental set up will look like.
|Control group||Experimental Group (s)|
|Amount of salt|
|Number of seeds|
|Amount of water|
|Draw what each set up will look like|
Step 2: Data
What data are you going to collect? You can collect data about how many seeds germinate, how long the roots get, how soon they germinate.
How many seeds will you use in your experiment? You need to get enough data to compare your different groups. Does your experiment include enough seeds? Enough replicates? The rule is usually at least 20 but can be less. _____________________
What will your data collection table look like?
Step 3: Set up the experiment and record the data.
Use the experimental design to set up your experiment. Recording the data can be as simple as counting, it could be taking photographs, it could be measuring. Whatever works best for the type of date you are trying to collect.
Step 4: Use some sort of analysis to compare your control group and experimental groups.
Usually this is an average but could just be a count. It is also common to make a graph to compare the collected data.
Step 5: Come to a conclusion.
What is the answer to your experimental question?
When you compare the seeds that were given salt to the seeds that were not what are the results. To do this use the claim, evidence, reasoning format. You can write this up, record a video, just tell us at the next meeting.
Claim: What are you saying is true?
Evidence: What observations have you made to say this is true?
Reasoning: Why do your observations mean your claim is true?