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 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

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