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Testing Stomatal Density in

LeavesAuthors deleted

Transpiration in Plants

Evaporation of water from stomata

Loss of water creates pulling force

Helps plants collect vital minerals

97% of water evaporates

Transpiration Rates

increase in higher temperature and wind

regulated by stomatal opening and closing

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Formulating Research Topic

Leaf thickness article:

Relates thickness/stomatal density to light intensity

Leaves in direct sun thicker more stomata

Plant-water relations article:

Stomatal density affects transpiration rates affect

photosynthesis rates

Light of low intensity less effective than stronger

illumination in inducing stomatal opening

Formulating Research Topic

Questions

Sun v. shade effect # of stomata?

Sun v. shade effect rate of transpiration?

• Hypothesis

Differences exist regarding stomatal density and

transpiration rates when Liquidambarst styraciflua(Sweetgum) is located in a sunny environment and when it

is located in a shady environment

• Prediction

Leaves in sunny environment have higher stomatal density

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Architecture of Experiment

Testing

Leaves

Sunny v. Shady

Conditions

SweetgumLiquidambarst styraciflua

•Large tree

•Easily identified by Leaves•Not native to California

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Methods & Materials

Test: Porometer measures stomatal conductance

1. Find Sweet gum in shade

2. Get reading, repeat for sun environment

3. 6 Readings in total!

Sample Size: 6 plants

3 in shade

3 in sun

Location: LMU School grounds

Statistics: T-Test

Methods & Materials

Test: Nail Polish Leaf Impression1. Acquire 6 sunny & 6 shady leaves

2. Coat polish on both halves

3. Place tape on polish, remove

4. Tape on slides, view under microscope

5. Count stomata

Statistics: T-Test

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Results

CalculatingStomataDensity

Totalstomata/F.O.V

mm^2

Results

Porometer P value = 0.0318

P < .05

Hypothesis Stands

• Stomata Count• P value= 1.25781E-07

• P < .05

Hypothesis Stands

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Conclusion

Differences exist b/w stomatal density of Sweet gum

leaves in a sunny v. shady environment

Higher stomatal density in sun

Lower in shade

T-Test Supports Claim

Prediction Correct

Leaves in sun need higher stomatal density to facilitate &

control transpiration rates since in direct sunlight.

Literature Cited

Terashima, I. "Irradiance and Phenotype: Comparative

Eco-development of Sun and Shade Leaves in Relation to

Photosynthetic CO2 Diffusion." Journal of Experimental

Botany 57.2 (2005): 343-54. Print.

Bernard S. Meyer, "Plant-water relations," in

AccessScience, ©McGraw-Hill Companies, 2008,

http://www.accessscience.com