ABSTRACT
The allelopathic effect of the common walnut Juglans regia L. was examined by bioanalysis of
the extract on seed germination and growth of lettuce (Lactuca sativa L.) and tomato (Solanum
lycopersicum L.). Aqueous extracts of leaves of different concentrations (concentrated extract, 1:2,
1:4 and 1:8) were made to determine the allelopathic potential, and distilled water was used as a
control. The obtained results showed that the lettuce is more sensitive, and the tomato is more
tolerant to the applied concentrations of the aqueous extract of juglone. All applied concentrations
inhibited lettuce germination, while lower concentrations had stimulating effect on growth. In
tomatoes, the inhibitory effect was fond in concentrated solution and 1:2, while lower
concentrations had a stimulating effect. Allelopathy is a unique phenomenon in nature that is
relatively new in science, and the results of this experiment are not only important in botanical
research, but also have application in practice.
