A laboratory experiment was conducted to assess the effects of allelochemicals of Eucalyptus camaldulensis, Eucalyptus citriodora and Eucalyptus globules on germination and root elongation using leguminous crop ground nut (Arachis hypogea) as bioassay material. The experiments were conducted in sterilized petridishes. The effect of different concentration of aqueous extracts was compared with distilled water (control). The result revealed that different concentrations of E. globulus and E. camaldulensis extracts caused highly significant (p=0.05) inhibitory effect on germination and root elongation. The bioassays indicated that the inhibitory effect was proportional to the concentrations of the extracts so that higher concentration has a stronger inhibitory effect. The study also revealed that inhibitory effect was much pronounced in root development rather than seed germination.
Key words: Allelochemicals, Eucalyptus species, Root length, Germination, Arachis hypogea