| Explore | Pea seeds have a thicker seed coat that prevents water from getting into the embryo. By weakening this seed coat, water can get to the embryo to grow faster and better, causing the pea to germinate earlier than it would have. |
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| Research Question | How does weakening the seed coat by rubbing sandpaper or nail files on it affect the speed of germination? |
| Predictions | We think that the seeds with the more scarified seed coats will grow faster than the seeds with the less scarified seed coats because the embryo can break out easier? |
| Experimental Design | To start you need four petri dishes, four paper towels, twelve pea seeds, and sandpaper (or a nail file). Dampen your paper towels and place one inside each petri dish. Be careful not to wet the paper towel too much, or the seeds will drown. Your paper towel will be the growing medium, so you do not need soil or sand. You have three seeds as the control. Place them in the first petri dish. Now use your sandpaper (or nail file) and very lightly scarify three seeds and put those in the second petri dish. Then you want to scarify three more seeds, but more than the ones that you've already scarified. Place those in the second to last petri dish. Finally, scarify the last three seeds remaining as much as possible without hurting the embryo before putting them in the last petri dish. Let your seeds grow for two and a half weeks, before taking them out. Take photos, and qualitative and quantitative observations. For your observations, you can note: the height, weight, width, amount of growth, changes from last observations, color, amount of time passed between notes (date, and time, if you think it's necessary). Variables that you are changing are how scarified the seed coats are. Or in some seed cases, how much water may be able to get to the embryo in a certain about of time. Variables that you are keeping the same are the gravity, light, water amount, allelopathy, and growing medium. |
| Conclusion | Our hypothesis was not supported at all by our data. It turns out that we were completely wrong. As you can see in this graph, instead of the extremely scarified seeds being super fast and growing really well. We got the results that we did because we unknowingly damaged the seeds’ embryos while we were scarifying them. When we researched about scarification, many of our sources stated that some seeds actually need to be scarified in order to germinate. We also learned that scarification speeds up germination. So we decided to test that. But instead, we damaged the embryo, because not all seeds need scarification, and some seeds are even hurt by it.. |
| Investigation Theme | WOS |
| Grade Level | Middle School Students (grades 6,7,8) |
| School Name | San Francisco Friends School |
| Session | Spring 2017 |
