Abstract
This study aimed to examine the allelopathic potential of Eucalyptus and Calotropis species on seed germination and seedling growth of Acacia ehrenbergiana (Hayne), Acacia gerrardii (Benth.) and Acacia tortilis (Forssk.). The aqueous leaf extracts of Eucalyptus camaldulensis var. obtusa (Blakely), E. intertexta (R.T.Baker), and Calotropis procera (Aiton) inhibited the seed germination, reduced the seedlings growth, biomass yield and biomass allocation in Acacia species. It suggests the further testing at farmers' fields to determine the allelopathic effects of Eucalyptus and Calotropis as invasive species in woodlands in central Saudi Arabia.