Allelopathic ToxinsAllelopathic Toxins

Plant AllelopathyPlant Allelopathy

• Plant allelopathy: the secretion or Plant allelopathy: the secretion or admission of a toxin or chemical from one admission of a toxin or chemical from one plant in order to inhibit the growth of plant in order to inhibit the growth of another plant another plant

Mechanisms of ReleaseMechanisms of Release

• Released through glands on roots or in Released through glands on roots or in leaves leaves

• Released by the decay of fallen leaves Released by the decay of fallen leaves and dead roots and dead roots

• Leached from the leaves when rain or Leached from the leaves when rain or fog passes over the leaf and drips offfog passes over the leaf and drips off

IntroductionIntroduction

• Black Walnut trees are found in the Black Walnut trees are found in the Midwest and East in the United States.Midwest and East in the United States.

• Some varieties of the Black Walnut are also Some varieties of the Black Walnut are also found in Europe.found in Europe.

IntroductionIntroduction

• Toxins found in the roots, leaves, and in Toxins found in the roots, leaves, and in the husks surrounding the seeds of the husks surrounding the seeds of Black Walnut trees Black Walnut trees

• Will not kill everything, but it Will not kill everything, but it does affect a variety of plants does affect a variety of plants commonly used for commonly used for landscaping and various landscaping and various garden vegetablesgarden vegetables

IntroductionIntroduction

• 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 HypothesisExperimental Hypothesis

• If grasses are watered with different If grasses are watered with different concentrations of walnut extract, the concentrations of walnut extract, the grass watered with the highest walnut grass watered with the highest walnut extract will have the most inhibited extract will have the most inhibited growth. growth.

Materials

• Walnuts

• Green house

• Beakers

• Graduated cylinders

• Kentucky blue grass

ProcedureProcedure

• Grass chosen: Kentucky BluegrassGrass chosen: Kentucky Bluegrass• The grass seeds were planted and allowed to The grass seeds were planted and allowed to

grow in a Green House for two weeks. grow in a Green House for two weeks. • The grasses were divided into 4 groups. Each The grasses were divided into 4 groups. Each

group was given a different concentration of group was given a different concentration of walnut extract. The control group was walnut extract. The control group was watered with tap water.watered with tap water.

• The grass appearance and growth was The grass appearance and growth was measured once a week for 3 weeks. measured once a week for 3 weeks.

Walnut Extract• Solution #1, one walnut : one liter HSolution #1, one walnut : one liter H22OO

• Solution #2, three walnuts : one liter HSolution #2, three walnuts : one liter H22OO

• Solution #3, five walnuts: one liter HSolution #3, five walnuts: one liter H22O O

• Soaked in a refrigerated room for two days Soaked in a refrigerated room for two days with stirring every 12 hours with stirring every 12 hours

• Walnuts removed and the solution Walnuts removed and the solution was refrigerated until its use (3 days)was refrigerated until its use (3 days)

• Four groups of plants were watered Four groups of plants were watered accordingly (20 mL every other day)accordingly (20 mL every other day)

• Solution #1: Group ASolution #1: Group A

• solution #2: Group Bsolution #2: Group B

• solution #3: Group Csolution #3: Group C

• Water: ControlWater: Control

ResultsResults

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

ConclusionsConclusions• This experiment and other similar This experiment and other similar

experiments have identified that Kentucky experiments have identified that Kentucky blue grass is inhibited by the toxic black blue grass is inhibited by the toxic black walnut.walnut.

One Final NoteOne Final Note

• In recent years more work has been done In recent years more work has been done in the field of plant alleopathy. This work in the field of plant alleopathy. This work has lead to the discovery of medicinal has lead to the discovery of medicinal uses for the jugalone toxin. Jugalone is uses for the jugalone toxin. Jugalone is considered an antiseptic, a germicide, a considered an antiseptic, a germicide, a parasitic, and a laxative. Perhaps more parasitic, and a laxative. Perhaps more disease fighting uses can be found for disease fighting uses can be found for allelopathic chemicals, as they are allelopathic chemicals, as they are examined further.examined further.

Works CitedWorks 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 EndThe End