Catechol and pyrogallol are allelochemicals which belong to phenolic compounds synthesized in plants. Their antimicrobial activities were investigated on three bacteria (Pseudomonas putida, Pseudomonas pyocyanea, Corynebacterium xerosis) and two fungi (Fusarium oxysporum, Penicillium italicum) phytopathogenic species as test organisms using the disc diffusion method. Both catechol and pyrogallol were found to have antibacterial effects on all the bacteria used in the study at 5 and 10 mm concentrations. Catechol has also been found to have an antifungal effect on the fungi used in the study, whereas no antifungal effects of pyrogallol were observed. The most sensitive species among the bacteria was P. putida which was inhibited by the allelochemicals even at 1 mm concentration.

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Effects of juglone on seedling growth of cucmnber (Cucumis sativus cv. Beith Alpha) with respect to physiological and anatomical parameters were investigated. Growth parameters (seedling elongation, fresh and dry weights) were reduced by 1 mM juglone. Juglone also decreased chlorophyll a and b contents and reduced some anatomical tissues (xylem vessel and bundle radius of stem, stomata length and stomata number of the cotyledons). The anatomical changes in stem and cotyledon of the seedlings were related to growth inhibiting effect of juglone. On the other hand, increase in catecholase and tyrosinase activities by the effect of juglone were also recorded.

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