The Effect of Allelochemicals
on Plant Growth
A project by: Cody Franko
Period 10 Honors Biology
Problem and Hypothesis
Problem Statement:
 How
will a plant’s growth be affected if it is
planted next to a sweet potato plant that
releases high levels of allelochemicals?
Hypothesis:

If a plant is planted next to a sweet potato
plant that releases high levels of
allelochemicals, then the plant will not grow
as efficiently.
Basic Concepts

Allelopathy- The releasing of secondary
metabolic products into the environment.

Allelochemicals- chemicals that are released by
volatilization in the form of edible tissues.

Ipomoea Batatas- the scientific name for a
sweet potato plant.
Basic Concepts

Do the average garden plants release any
allelochemicals, if so than how much do they
release?

What are the levels of allelochemicals released from
a sweet potato plant?

How should I water the plants, as one or two
separate?

Is there a set temperature the room should be while I
grow these plants?
Procedure

Plant all of the plants in the pots at different
distances.

Use sweet potato plants for allelochemicals and
sunflower plant as average plant.

Water daily with 150 mL of water

Monitored growth
Design Diagram
Levels
5cm
10cm
15cm
20cm
Control:
not planted
next to
sweet
potato
plant
Trials
6
6
6
6
6
CONSTANTS: Same temperature water, same types of plants, same amount of
sunlight, same soil, same amount of water.
Safety Precautions

Do not consume plants or soil.

Do not “Play” with pots they might
break!
Results
Control
5 cm
10cm
15 cm
20 cm
Trial 1
14
7
7.5
9
11
Trial 2
13
7
7
10
12.5
Trail 3
13
9
8
6
12
Trail 4
14
8
8
10
9
Trail 5
12
10
8
10
13
Trail 6
10
8
6
12
12
Average
Height
12.7 cm
8.1 cm
7.5 cm
9.5 cm
11.6 cm
Null Hypothesis

Allelochemicals have no effect on
plant growth.
Anova Test
ANOVA: Results
Source of
Sum of
d.f.
Mean
Variation
Squares
between
118.9
4
29.72
error
51.08
25
2.043
Total
170.0
29
F
Squares
Significance of 0.00
Null can be rejected
14.55
Photodocumentation
Photodocumentation
Photodocumentation
Graph
Conclusion
Allelochemicals
do have
an effect on plant growth.
Hypothesis
was supported
Sources of Error

Not exposed to enough Sunlight

Not enough time given for plants to
grow

Inconsistent amounts of water
Improvements

More trials

Done in warmer and sunnier
conditions

More precise measurements
Extensions and
Applications

Do experiment with different plant
types like weeds and fruits

Useful for gardening techniques
Acknowledgements

Mrs. Pietrangelo

My Mom
Bibliography

Ferguson, James, and Bala Rathinasabapathi. "Allelopathy: How Plants Suppress Other
Plants." University of Florida, July 2003. Web. 5 Oct. 2010. <http://
edis.ifas.ufl.edu/hs186>.

INDERJIT, and K. G. MUKERJI. Allelochemicals: Biological Control of Plant Pathogens and
Diseases. Dordrecht: Springer, 2006. Print.

Kavassalis, Catherine. "Allelopathy for the Home Gardener." Halton HELPs. Web. 05Oct.
2010. <http://haltonhelps.org/Egardening/Allelopathy.htm>.

Harrison, Howard, and Joseph Peterson. Allelopathic Effects of Sweet Potatoes onYellow
and Alfalfa 34.4 (1986): 623-27. Web. 5 Oct. 2010. <http://http://
www.jstor.org/pss/4044250>.
Nutsedge

Hunter, Sheri. "Guidelines for Watering Indoor Plants." Guidelines for WateringIndoor
May 2010. Web. 5 Oct. 2010. <http://www.coopext.colostate.edu/
4dmg/Plants/guidline.htm>.
Plants. 1

Wolford, Ron, and Drusilla Banks. "Sweet Potato - Vegetable Directory - Watch Your Garden
Grow - University of Illinois Extension." University of Illinois. Web. 05 Oct. 2010.
<http://urbanext.illinois.edu/veggies/sweetpotato.cfm>.