Abstract
We all know that plants need sunlight and water to grow big and tall. But did you know that inside seeds are baby plants, and that the fragile baby plant inside the seed needs to be protected? If you've ever had a sunburn, you also know that the sun gives off harmful radiation and heat. How much radiation and heat can a seed handle? Find out using some radish seeds, an oven, and your microwave!Summary
Objective
To determine the effect of radiation and heat on the germination of radish seeds.Introduction
You might already know that if you plant a seed it will grow into a plant. But did you know that inside of every seed is a baby plant? The inside of a plant seed has three main parts: the embryo is the baby plant, the endosperm is food for the baby plant, and the cotyledon(s), which look like leaves and contain the endosperm. All of the parts of the baby plant are enclosed and protected by a special covering called the seed coat. The seed coat protects the baby plant embryo from many different conditions, some of these conditions can be: drying out, freezing temperatures, heat, radiation, or acidity.
Some seeds have very large and tough seed coats while others have very weak and fragile seed coats. This is because different kinds of plants have adapted to different environments, and so need to be protected from different things. Desert plants need protection from drought, arctic plants need to be protected from cold winter temperatures, and plants from pine forests often need protection from forest fire. In fact, seeds from some forest plants need a forest fire before they can sprout through their tough, protective seed coats!
Seed sprouting is called germination, and is the process during which the baby plant emerges from the seed and develops its first set of true leaves. Germination begins when the seed absorbs water, which causes the endosperm to swell and pop open the seed coat. Then the embryo will grow and develop its first set of true leaves, using food stored in the endosperm for energy. Some seeds take a very long time to germinate, while others germinate very quickly. For this experiment, we have chosen radish seeds, which germinate very quickly in 3 to 5 days.
Plants use energy from the sun to grow and make food in their leaves. Some of the sun's energy is in the form of ultraviolet radiation, sometimes called UV rays. The UV radiation from the sun is one kind of electromagnetic radiation. Electromagnetic radiation is also produced by many household appliances, like radios, cell phones, televisions, and your microwave. When you use a microwave, the microwaves travel through your food, causing the food to cook. In this science project, you will use a microwave to expose seeds to electromagnetic radiation. Sometimes electromagnetic energy can cause heat, and in your experiment you will heat the seeds by baking them in the oven.
Terms and Concepts
To do this type of experiment you should know what the following terms mean. Have an adult help you search the internet, or take you to your local library to find out more!- Seed
- Embryo
- Seed coat
- Sprout
- Germinate
- Heat
- Temperature
Bibliography
- University of Illinois Extension. (n.d.). The Great Plant Escape. Retrieved February 28, 2012, from http://www.urbanext.uiuc.edu/gpe/index.html
- Gibbons, Gail. 1991. From Seed to Plant. New York, NY: Holiday House. Print.
- Rockwell, Anne. 1998. One Bean. New York, NY: Walker & Company. Print.
- Koning, R. (n.d.). Seed Germination. Plant Physiology Information Website. Retrieved February 28, 2012, from ttp://plantphys.info/seedg/seed.html
- Hangarter, R. (n.d.). Corn Germination. Plants-In-Motion. Retrieved February 28, 2012, from http://plantsinmotion.bio.indiana.edu/plantmotion/earlygrowth/germination/germ.html
Materials and Equipment
- radish seeds
- oven (you will needs your parents supervision)
- microwave
- napkins
- permanent marker
- aluminum foil
- tape
- Zip-Lock baggies
- water and a dropper
- a sunny window
Experimental Procedure
- Before you start, have an adult preheat the oven to 250 degrees.
- Now you can start to set up your experiments. To set up for each experiment, you will need to do a lot of labeling and organizing, so that your seeds won't get mixed up with each other. To do this you can label each zip lock baggie with a permanent marker.
- You will need to label one baggie for your "control" group, one baggie for each group of microwaved seeds, and one baggie for each group of baked seeds. Label each microwaved seed baggie with "MW" and the time you microwaved your seeds: "5 seconds," "10 seconds," "20 seconds," etc. Label each baked seed baggie with "B" and the time you baked your seeds: "10 minutes," "20 minutes," "30 minutes," etc.
- Now you are ready to turn each baggie into a miniature greenhouse. Place a folded napkin in the bottom of each baggie making sure it lies nice and flat.
- Add a few drops of water into each baggie until the napkin is evenly moist, but not dripping wet. Keep the baggies ready, so that as you treat your seeds you can put them inside the baggies, zip the baggie closed, and tape it to a sunny window.
- One more important thing to do is to set up a "control" group. This group of seeds will not be microwaved or baked in the oven. The reason for having a control group is so that you know your seeds are good and can sprout. What if the seeds you bought are bad? For this group, take the bag labeled "control" and add 10 radish seeds to the bottom of the bag on one side of the napkin, close the baggie and tape to the window.
- For the microwave experiment, you will be taking groups of 10 seeds and microwaving them for different amounts of time. Count out 10 radish seeds, place on a dry napkin, and microwave for a period of time (5, 10, 15, or 20 seconds).
- Place the seeds into the matching bag with the correct label, close the bag, and tape it to the window.
- For the baked seeds you will need your parents help—remember the oven will be very hot! Make some little squares of aluminum foil and fold up the outer edges to put your seeds into.
- Place each little tin on a cookie sheet and fill with 10 seeds.
- Place the entire cookie sheet onto the oven, which has been preheated to 250 degrees.
- Take out a group of seeds about every 10 minutes, so that the time in the oven will match the time on each baggie.
- Place the seeds into the matching bag with the correct label, close the bag, and tape it to the window.
- Let all of your experiments sit taped to the window for 3 to 5 days. After that time you will notice that some of the seeds have sprouted. Do not open the bags or add water during this time, if they were sealed properly they will not dry out or run out of air.
- After the seeds have sprouted, write the number of sprouted and un-sprouted seeds on the baggie for each group. Record your data in a table, here is an example of how to make a table:
Group Time Treated Number Sprouted Number Un-sprouted Control none Microwaved 10 seconds Microwaved 20 seconds Baked 10 minutes Baked 20 minutes Etc. Etc. - After you have finished counting up all of your seeds and sprouts, you are ready to make a graph. There are many different types of graphs you can use for this experiment. The simplest type of graph will be a bar graph. On the left side of your graph, called the Y-axis, you will put the number of seeds sprouted from 1 to 10. On the bottom of the graph you will put your different groups. Draw a bar for each group that indicates how many seeds sprouted for that group.
- From your graph, you can compare the seeds from your different experiments to your control seeds. Do more seeds sprout, or less seeds sprout in your experiments? What do you think happens when the seeds are exposed to microwaves? What do you think happens when the seeds are heated? What does this tell you about seeds?
Ask an Expert
Variations
- Think about temperature in your seed experiment. Do you think all of the seeds were heated to the same temperature? Is the temperature of the oven the same as the temperature of the microwave? You can calculate the actual temperature the seeds were exposed to in the microwave by heating up a cup of water and measuring the starting and final temperature using a candy thermometer. You can measure the accuracy of your oven temperature by using an oven thermometer. How did the temperature of the microwaved seeds compare to the baked seeds? Was one method hotter than the other? How did the temperature change as more time was added? Could you use this new information to adjust the treatment times in your original experiment?
- You can try the same experiments on different types of seeds. Do different plant species have seeds that are more tolerant to these conditions?
- You can also try experiments with more conditions. For example, acidity can be a problem for some seeds, but good for others. You can use vinegar to test the effects of acid by mixing with the water you use to keep your seeds moist.
- Did you know that some seeds sprout better in the dark? You can try different types of seeds in the light and in the dark to see which conditions are best for each type of seed.
- Here is an amazing seed fact: Ancient seeds have been found by scientists frozen deep in arctic ice, and when scientists tried to grow these seeds they sprouted! Try this experiment yourself by putting some seeds in the freezer.
Careers
If you like this project, you might enjoy exploring these related careers:
