Radish Root Races
Overview
Plants need roots to absorb water and nutrients and to hold the plants firmly in place so they can grow up. Growing strong roots helps plants tolerate drought, withstand bad weather, and produce lots of healthy offspring. People study root growth to help farmers and gardeners grow plants with strong roots. In this experiment, you will try different things to see how they affect root growth.
And so begins an experiment in middle school science to learn not only about plants, but to learn about how science is done. Below you will find the materials we used to:
- Help students conduct controlled experiements testing the effects of different conditions on root length.
- Help students share what they found with their class mates.
- Help students use their classmates findings to determine the combination of conditions they will try in the culminating race to grow the radishes with the longest, shortest, least deviating roots, or most deviating roots.
The Documents
The Set Up
- We used fold over the top sandwhich bags.
- We got brown paper from our art teacher, it is similar to brown grocery bag paper. The brown makes it easier to see the roots.
- Put a line about a centimeter from the top
- Students put their name and their ** root-growing conditions for nutrients and sunlight on the paper, in this case growing in complete fertilizer solution and full sun.
5. Set up the bag with the appropriate growing conditions: 1) Add 15 ml of solution, in this case fertilizer, to the bag. Help it move about until the entire paper is wet. 2) Give it full sun-- by taping the bag to a sunny window.
**The root-growing variables we used were:
- Nutrient options: full fertilizer, water, nitrogen strong solution, phosphorus-strong solution, and potassium-strong solution
- Sunlight options: Full sun, indirect sun, and no sun.
6. We soaked the seeds in a petri dish over night sitting on top of saturated brown paper towel. They can soak longer and you'll have greater germination.
7. Add a row of radish seeds to the line draw at the top of the paper.
8. Carefully flatten the plastic bag to remove air bubbles. Seeds can be gently repositioned through the bag if they slip out of place.
9 . With the bag smooth and wet, the seeds will stay in place if handled gently.
10. We taped bags to the windows for direct light, pinned to a bulletin board for indirect light or taped them inside a closet door for dark.
11. Depending on your room conditions, you may have to add water to your bags.
Final Thoughts
The timing of this experiment is very flexible. It is simple enough to watch them grow and end the activity when they are long enough to measure. The shortest amount of time would be to soak the seeds Thursday night, plant in bags on Friday, watch them during the next week and then measure them on Friday.
In the first round of growing, we(the teachers) picked and assigned the growing conditions for each student. We have six classes between us, so two classes put their bags in direct sun, two classes put their bags indirect sun, and two classes put their bags in direct sun. Within each class, we assigned about four students to use each **nutrient solutions. With five or six radish seedlings growing in each bag, this set-up allowed for many trials with each combination of conditions. Students were able to draw conclusions based on a large amount of data.
**We chose solutions strong in Nitrogen, Phosphorous, or Potassium as well as water and a complete liquid fertilizer. We purchased sources of these nutrients at our local garden center and then made saturated solutions with room temperature tap water. We used Miracle Grow for the liquid Fertilizer.