Name______Date______Per______

Transpiration

1.  Water and drain your plant well.

2.  Separate 4 plants that are about the same size from your pot.

3.  Wrap the root ball of each with a plastic bag (include the dirt)

4.  Tie the bag closed at the stem with string. Label your group and the treatment type.

5.  Measure the masses of each of the four plants.

6.  Place the plants in different environmental conditions in the room:

a.  The control out of a draft.

b.  Three feet away from a fan on low

c.  Three feet away from a flood light

d.  Under an inverted aquarium that has had water misted into it (make sure to mist daily)

7.  Measure the masses of each plant every day for one week.

8.  Plot the changes in mass on a single graph. Percent change in mass can be calculated if necessary.

Transpiration Data
Type / Monday / Tuesday / Wednesday / Thursday / Friday
Control
0* / 0%
Light
0* / 0%
High Humidity
0* / 0%
Fan
0* / 0%

*Cumulative data should be entered in these rows. Subtract each day’s mass from the original mass. To calculate percent change, divide change in mass per day by the original mass.

Calculate the water loss per square meter of leaf surface area

Example Actual Data

1 / Mass all the leaves on your plant / 6 g
2 / Mass one cm2 section / .06 g/cm2
3 / Multiply sections’ mass (#2) by 10,000 to get mass per square meter of leaf / .06 g/cm2 x 10,000 = 600 g/m2
4 / Divide total mass of leaves (#1) by mass per square meter (#3). This is the leaf surface area in meters squared. Record the surface for your 4 plants in the table below. / 6 g ÷ 600 g/m2 = .01 m2
5 / Divide your change in grams on the last day of the transpiration lab by surface area (#4). Record these changes in the table below. You must include for all 4 plants in your group / 50.5 g divided by .01 m2 = 5050 g/m2

Calculate Leaf Surface Area (#4)

Leaf surface area = m2

Leaf Surface Area (Control) / Leaf Surface Area (Light) / Leaf Surface Area (Humidity) / Leaf Surface Area (Fan)

Group Data: Calculate water loss per square meter of leaf surface area (#5)

Last Day g/m2
Control
Light
High Humidity
Fan

Class Average Cumulative loss in g/m2

Last Day g/m2
Control
Light
High Humidity
Fan