Transcript Allelopathic Toxins and the Black Walnut (Juglans nigra)

Allelopathic Toxins
Plant Allelopathy
• Plant allelopathy: the secretion or
admission of a toxin or chemical from one
plant in order to inhibit the growth of
another plant
Mechanisms of Release
• Released through glands on roots or in
leaves
• Released by the decay of fallen leaves
and dead roots
• Leached from the leaves when rain or
fog passes over the leaf and drips off
Introduction
• Black Walnut trees are found in the
Midwest and East in the United States.
• Some varieties of the Black Walnut are also
found in Europe.
Introduction
• Toxins found in the roots, leaves, and in
the husks surrounding the seeds of
Black Walnut trees
• Will not kill everything, but it
does affect a variety of plants
commonly used for
landscaping and various
garden vegetables
Introduction
• Symptoms of walnut toxicity are wilting
of plants.
• If the plant has only a mild reaction to
the toxin, poor flower development and
stunted growth are noted.
Experimental Hypothesis
• If grasses are watered with different
concentrations of walnut extract, the
grass watered with the highest walnut
extract will have the most inhibited
growth.
Materials
•
•
•
•
•
Walnuts
Green house
Beakers
Graduated cylinders
Kentucky blue grass
Procedure
• Grass chosen: Kentucky Bluegrass
• The grass seeds were planted and allowed
to grow in a Green House for two weeks.
• The grasses were divided into 4 groups.
Each group was given a different
concentration of walnut extract. The
control group was watered with tap water.
• The grass appearance and growth was
measured once a week for 3 weeks.
Walnut Extract
•
•
•
•
Solution #1, one walnut : one liter H2O
Solution #2, three walnuts : one liter H2O
Solution #3, five walnuts: one liter H2O
Soaked in a refrigerated room for two days
with stirring every 12 hours
• Walnuts removed and the solution
was refrigerated until its use (3 days)
• Four groups of plants were watered
accordingly (20 mL every other day)
• Solution #1: Group A
• solution #2: Group B
• solution #3: Group C
• Water: Control
Results
Growth
Control
Group A
Group B
Group C
10 cm
7 cm
5 cm
2 cm
Some
wilting
Wilting
Wilting
and yellow and brown
appearance Green
Conclusions
• This experiment and other similar
experiments have identified that Kentucky
blue grass is inhibited by the toxic black
walnut.
One Final Note
• In recent years more work has been done
in the field of plant alleopathy. This work
has lead to the discovery of medicinal
uses for the jugalone toxin. Jugalone is
considered an antiseptic, a germicide, a
parasitic, and a laxative. Perhaps more
disease fighting uses can be found for
allelopathic chemicals, as they are
examined further.
Works Cited
• Abraham, D. "The Green Thumb."
Consumer's Research Magazine. April 1992: 37-38.
• "The Curse of the Black Walnut." Country Journal.
December 1997: 80.
• Fuchs, Lucy. "Natural Connections." American
Horticulturist. February 1995: 14-16.
• Meyer, P.W. "Underground Battles." Horticulture.
October 1990: 11-13. 5.
• Orr, Tamra B. "Black Walnut." Better Nutrition. March
1999: 44-45.
Honeysuckle
Does honeysuckle have
allelopathic properties?
• Scientists are currently researching this
question.
• How can you test this question?
• What specific questions can you ask and
then test?
The End