Allelopathic Toxins

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Allelopathic Toxins
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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

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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

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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.

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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

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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.

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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.

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Materials

• Walnuts
• Green house
• Beakers
• Graduated cylinders
• Kentucky blue grass

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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.

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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)

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• 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

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Results
Control Group A Group B Group C
Growth 10 cm 7 cm 5 cm 2 cm
appearance Green Some wilting Wilting and yellow Wilting and brown

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Conclusions

• This experiment and other similar experiments
  have identified that Kentucky blue grass is
  inhibited by the toxic black walnut.

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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.

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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.

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Honeysuckle
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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?

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The End