A Petri dish assay was carried out to study allelopathic potential of foliar aqueous extract of Eucalyptus camaldulensis on germination and seedling growth of some weeds including Acroptilon repens, Plantago lanceolata and Portulaca oleracea. Seed germination, rate of germination, root and shoot length of weeds exhibited different degree of inhibition according to the concentration of the aqueous extract. Maximum inhibitions on germination percentage, rate of germination and seedling growth were recorded when using the highest concentration of the aqueous extract (20g/l) of Eucalyptus. Seed and rate germination of Portulaca weed were not affected by aqueous extract of Eucalyptus camaldulensis. However, seed germination and germination rate of Acroptilon repens and Plantago lanceolata were severely affected by aqueous extract of Eucalyptus camaldulensis. Aqueous extract of Eucalyptus camaldulensis affected seedling growth of all weeds even Portulaca oleracea so that root and shoot length of Portulaca oleracea decreased by 83.3 and 68% at high aqueous extract concentration (20g/l) respectively, compared to control. Root length was more affected than other parameters by aqueous extract of Eucalyptus camaldulensis.

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