Night Watch: Can We Train a House Plant to be Awake at Night?
Purpose or Problem
The purpose is to see if a plant's natural biological rhythms are upset (as evidenced by an observable change in the plant) when normal daylight and dark nighttime periods are reversed.
Are you tired at 3 A.M., and wide awake with lots of energy at 3 P.M..? Our bodies have a natural pattern of sleep and waking times. Have you ever tried to switch your sleep/wake time, so you are awake in the night and sleep in the day? Certain jobs, such as factory or police swing-shift workers, have alternating day/night work schedules. People who travel to foreign countries often suffer jet lag, as their bodies' "circadian rhythms" are upset by the different times of sunlight and eating meals. Jet lag can cause many problems, including fatigue, cloudy thinking, and irritability.
Plants, animals, and people have daily biological rhythms. As far back as the fourth century BC, the scribe of Alexander the Great, Androsthenes, observed that the leaves of certain trees opened during the day and closed at night. Leaves of the heliotrope plant have a similar action, as do day lilies. Bees visit flowers at specific times of the day. Rhythms in other animals are also now well known.
Just as people need a period of rest at some time during a day/night cycle, so do plants. If we change the time of day a plant is exposed to light, will that result in a noticeable effect on its growth or health?
Hypothesize that changing the time of light and dark during a 24-hour period will cause an observable effect on a plant within an eight-week period. Observable effects include growth, color, size, turgor, and general healthy appearance. (You may want to hypothesize that no noticeable effects will occur.)
- Nine equally healthy house plants
- Two dark closets
- Two plant grow light bulbs
- Kitchen measuring cup
- Eight weeks of time
Obtain nine equally healthy, identical types of house plants. Obtain two equal wattage plant grow lights, available at your local nursery or garden center. These indoor lights supply the proper wavelengths of light to grow plants without sunlight. Locate two closets that are on the same floor in your home. They must have doors on them, so when the doors are closed, the closets are completely dark.
Place three plants in each closet. Place a plant grow light in each closet. Set the three other plants in an out-of-the-way area in a living room or dining room, where they will receive ample light, but not be in direct sunlight from a window. The plants in the living room will receive normal light during daylight hours and normal darkness in the room at night.
For the plants in one closet, turn the plant light on from 8 A.M. to 8 P.M. daily, leaving them in the dark during the evening.
In the other closet, turn the plant light on from 8 P.M. to 8 A.M., so the plants are in the dark during the day, but receive light during the night.
Monitor the plants for eight weeks. When you water the plants, use a kitchen measuring cup, so you give an equal amount of water to each of the nine plants. Keep the soil moist, but not drenched. Another constant—temperature—is assumed to be about equal in the closets and living room.
Write down the results of your experiment. Document all observations and data collected.
Come to a conclusion as to whether or not your hypothesis was correct.
- Deprive a plant of a rest period. Compare a plant that gets a normal amount of light during the day and dark at night to a plant that receives constant light and is never allowed a rest cycle. Observe the appearances of the plants after eight weeks under these conditions. Use at least four plants, two under each condition.
- Experiment with plants that demonstrate a very visible biological rhythm (for example, day lilies and morning glories).
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