The goal of this experiment is to determine whether varying certain factors, such as water location and light location, will cause plants to grow in a different direction than other plants that are grown through more conventional methods.
The idea behind this experiment is to determine whether plants are affected by both the location of their water and the location of their light source. You can choose just one of these things to test, or test both factors, so we will go ahead and describe ways of setting up both types of test.
What effect do you think the location of the water will have on the plant? How about the effect of the light's location? Specifically, do you think the plant will grow towards or away from the water and towards or away from the light?
- Lots of seeds of the same (fast-growing) plant. We recommend about 40 so that you can try and grow 20 plants.
- 20 plant pots or holders of some sort. Make sure they are roughly the same type of container, as you do not want to introduce other variables into your experiment.
- Potting soil to fill your plant containers.
- Water for keeping the plants alive.
- A ruler and a protractor, to measure the status of your plants' growths and to record the angle at which they are growing.
- Lights to allow the plants to perform photosynthesis.
- Record turntable or some other surface that can spin on its own.
- Dump some soil in each of the pots and plant 2 seeds per pot (to make sure they grow)
- Put all the pots together in a room under a light and water them for 2 weeks to allow them to germinate and start living
- Number the pots and measure the size of the plants.
- Place pots 1-5 in a row and put the lights to the side of the plants rather than above it.
- Place pots 6-10 on the turntable and start it turning (slowly). Try to make sure that the plants are all the same distance from the center. The light should be placed above the center of the turntable.
- Place pots 11-15 in a row and put the lights above the row of plants. This group should only receive water into the right half of the pot. The water should be poured in along the edge and you must be careful to always pour on the right side. (Note: It doesn't matter which side you pour into as long as you are consistent among this group and over the course of the experiment, making sure to always water the same side.)
- Pots 16-20 will be kept as a control group which will receive light from above, water in the middle of the pot, and no turntable effect.
- Continue watering your plants as explained and once a day measure the size of the plant, and also the angle from vertical at which the main stalk of the plant is growing. You may also want to count the number of leaves as that is indicative of how well the plant is growing.
Understanding how plants use light via photosynthesis as their "food" and how plants absorb water will help to start out this experiment, and will be reinforced by the results of the experiment.
Using the measurements you have dutifully recorded, you may want to average the results from each of the 5 pots in a group to come up with a group average for each day. Using this averaged plant size from each group, you can easily compare how well each group grew and which method worked out best in the topic of plant size. You can also take the average angles of the plants with respect to the ground and compare each group's angles. This will help you determine what kind of affect each variable had on the way the plant grew as well as just how much of an effect it had.
How did things turn out? Do plants grow toward water or away from it, or does the water have no effect on the direction of plant growth? Why do the plants behave in this way based on water location? How about for light; did your plants grow towards the light or away from it? Why do they behave that way with regards to the light? These are all questions you will need to carefully consider and answer, using your data and analysis to support your conclusions.