The Effect of Light Type on Plant Growth

By Katra

Why is it important?• The environment around

the world is constantly changing- due to that,the amount and type of light plants receive changes too. Figuring out how this affects plants could help us learn to stabilize the variables and help plants grow.

• Certain plants only grow well in certain conditions, partly due to light. If the type of light plants need to grow well is deter-mined, more plants would be able to grow in more places, improving the agriculture as a whole.

Ultraviolet Light

• Wavelength- The distance between two “waves” of light traveling through space.

• UV Light has a very short wavelength, invisible to the human eye.

• UV light is responsible for sunburns.

Infrared Light

• Is on the other end of the spectrum from UV light, has a long wavelength.

• Most objects emit energy at infrared wavelengths.

• Often invisible. Waves are thermal.

Photosynthesis• Plants turn sunlight,

water, and air, into sugar,and convert it into fuel by cellular respiration.

• Formula 6H2O+6CO2---> C6H1206+6O2, or 6 water molecules,plus 6 carbon dioxide molecules,->

make 1 sugar molecule plus 6 oxygen molecules.

Background Information

• Plants and light tie tightly into one another in the natural world, because without light plants would die, and thus without plants, over a period of time species all over the world would die out.

How it relates to the Focus

• The main purpose of this experiment was to find how Ultraviolet and Infrared light affected the growth of plants.

• The plants were monitored under a purple light, a red, and in regular daylight.

• What was supposed to be shown were the changes that might have occurred to plants receiving similar light in nature.

Experimental Design DiagramTitle: The effect of different types of light on plant growth.

Hypothesis: If a plant receives light with longer wavelengths, then it’s likely to grow better than a plant receiving shorter wavelengths.

IV: Types of light (wavelengths)

Control:RegularDaylight

InfraredLight

UltravioletLight

8 Trials 8 Trials 8 Trials

EDD...DV: Growth of Plant (centimeters)

General Specific

Type of Plant Bean Seedling

Amount of Light 8 Hours

Amount of Water 20mL

Amount of Seeds perPot

8

Amount of Soil 18 cm

Depth of Seed 8 cm

Procedure

•Put 18 centimeters of soil into 3 pots 20 centimeters tall.•Then plant 8 pea seeds 8 cm deep and 3 cm apart from each other.•After that water each pot with 20 mL of water.•Place the control by a window and the other two pots in the basement, one under an Ultraviolet lamp, the other under an Infrared.•Water all plants with 20 mL of water every other day for six weeks, starting Monday.•Measure the plant growth for each seedling (in centimeters) once a week for six weeks.

Derived Data TablesGrowth (cm) Infrared Ultraviolet ControlMean 2.75 2.8125 4.625Median 2.625 2.8125 4Range 3.5625 6.5 4.625Maximum 3.5625 6.5 4.625Minimum 0 0 0Trials 7 7 7

Data Weeks Infrared Ultraviolet Control11/14/01 0 0 011/21/01 2.1875 6.5 1.187511/28/01 3.5625 3.625 4

12/5/01 2.625 2.625 4.37512/12/01 2.75 2.8125 4.62512/19/01 0 0 0

Graph #1The Effect of Light Type on Plant Growth

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Infrared Ultraviolet Control

Light Type

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Median

Graph #2The Effect of Light Type on Plant Growth

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11/7/01 11/17/01 11/27/01 12/7/01 12/17/01 12/27/01

Dates Data was Taken

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Infrared

Ultraviolet

Control

Explaining the Results/Trends

• In general, each plant grew a particular way, the control growing the healthiest in the long run, infrared growing quickly and green, but dying soon, and ultraviolet growing tall and thin, pale and leafless.

Relating to the Environment• In this experiment,

daylight represented natural “white light”, the purple lamps the ultraviolet light, and the red lamp the infrared light.

•The main idea was to discover how plants in different environments receiving different amounts of light would grow differently, because of their living circumstances.

Possible Problems

• Bacteria might have affected individual plant growth.

• Light amount and strength may have varied.

• The distances seeds were planted and soil/air differences are also possible errors.

Topics for Further Study

• Stars- what they’re made of, how they effect Earth and other objects.

• Plants- learning in more detail about how they function and aid our world.

• Light- Also learning more about the specific wavelengths and types.

• Physics- Discovering how particles comprise the different parts of our existence.

Overall...

• It was seen that plants that receive light in the middle of the wavelength spectrum (regular daylight) grow the best.

• Plants getting Ultraviolet light grow very tall, but sickly, never very healthy and dying quickly.

• And plants with Infrared light grow very green and leafy fast, not growing very tall, and also dying soon.

Bibliography

• UV Sun- imagers.gsfc.nasa.gov/ems/uv.html

• Visible/Infrared Orion- sofia.arc.nasa.gov/Sofia/ science/sofia_sci.html

• Water Plants- graphics.stanford.edu/courses/ cs448c-00-fall/

The End