Lab Report Sample: The Effect of the Hormone Gibberellic Acid on the Growth of Dwarf Peas*

* In order to print this experiment properly, set your printout to size 80% or to horizontal.

I. Teacher or Student

Dana Hitchcock

II. School Name

Wheeling Jesuit University/NASA Classroom of the Future

III. E-mail Address

dana@cotf.edu

IV. Title of Experiment

The Effect of the Hormone Gibberellic Acid on the Growth of Dwarf Peas

V. Problem

How does the plant hormone gibberellic acid affect the growth rate and dwarf character of peas?

VI. Hypothesis

Gibberellic acid will increase the growth rate of genetically dwarf peas.

VII. Equipment/Apparatus

2 gallons potting medium

3 flats with segmented inserts

Package tall pea seeds

Package dwarf pea seeds

Vial gibberellic acid paste (500 ppm)

Toothpicks

Centimeter ruler

3 clear plastic lids or cellophane

VIII. Methods/Procedures

1. Prepare soil by mixing 2 gallons of soil with 8 cups of distilled water and let the mixture sit overnight.

2. Place the tall and dwarf seeds in 2 labeled containers of distilled water, and let the seeds imbibe overnight.

3. Label the first flat "control dwarf peas," the second flat "gibberellic dwarf peas," and the third "control tall peas."

4. Fill each segment with soil, and place 2 seeds at least 2 cm apart and 5 mm deep in each segment.

5. Cover the flats with clear lids or cellophane.

6. After the seeds germinate, remove covers from flats.

7. Select 1 seed from each segment - ones that appear healthy and most similar in height to the others in the flats. Discard the remaining seedlings.

8. Measure each seedling, and record its height to the nearest 0.5 cm.

9. Using a toothpick, smear gibberellic acid on the dwarf seedlings 2 mm thick from the soil to the tip of the plant.

10. Spray with distilled water until soil is moist throughout each flat.

11. Place flats under fluorescent or gro-lights.

12. Every second or third day, measure the plants, and record the date and height of each plant. Note any changes in appearance of the plants (color, branching, etc.). Water the plants before replacing under the lights.

IX. Results

1. Tables/Spreadsheets

2. Graphs

3. Brief summary of the data table and graph

According to our results, at 20 days after germination, the control dwarf peas only showed an average height of 15.8 cm, while the gibberellic acid-treated group of dwarf peas had an average height of 35.2 cm. The control tall peas had an average height of 32.4 cm. Performing a t-test on these values showed significant differences between the control dwarf and the gibberellic acid-treated dwarf peas (t=0.022) and between the control dwarf and the control tall peas (t=0.048). The t-test between the control tall and the gibberellic acid-treated dwarf peas (t=0.296) showed there is not a significant difference between these two groups.

X. Discussion of Results

1. Significance of Results

Since the gibberellic acid-treated peas grew to a height similar to that of the tall peas, and significantly more than the dwarf peas, the results suggest that gibberellic acid may replace the substance genetically missing from the dwarf peas or may otherwise enhance the growth of these peas.

Variations in the amount of gibberellic acid applied to the seedlings may account for variations in the heights of the treated dwarf peas. Errors of 0.5 to 3 cm may also occur in the measuring, especially when the peas start to grow tall and twist. Temperature and light intensity under the fluorescent lights were not measured. It is possible that differences from one position to the next might influence growth rates.

2. Applications to Advanced Life Support (ALS) Research

It might be possible that hormonal treatment could increase the food production in potential ALS crops. It would be interesting to measure the growing time and food production of other dwarf species, to determine if it might be more efficient to have dwarf species in an enclosed environment rather than their normal, taller counterparts.

3. Future Experiments

Additional investigations on the effects of gibberellic acid may be done such as measuring the effects of gibberellic acid on the plant weight and leaf size, comparing the number of pea pods produced by dwarf, tall, and gibberellic acid-treated peas, or studying the effects of gibberellic acid on other species of plants. Another investigation could involve treating a set of tall pea plants with gibberellic acid to see if the growth rates of the treated group increases beyond that of a control tall group.

Conclusion

The data support the conclusion that gibberellic acid increases the growth rate of genetically dwarf peas.

Questions or comments specific to this experiment:

Previous Page


NASA Classroom of the Future

Please email questions about BioBLAST to BBteam@cet.edu.
Please email comments about this site to Webmanager@cet.edu


Privacy Statement and Copyright 1997-2000 by Wheeling Jesuit University/NASA Classroom of the Future™. All rights reserved.