Allelopathic activity of Eucalyptus globulus leaf aqueous extract on Hordeum vulgare growth and cytogenetic behaviour

Allelopathy is a major factor that influences the establishment of native species in eucalyptus forests.In this study, different concentrations of aqueous leaf extract of Eucalyptus globulus (5%, 10%, 5%, 25%) were evaluated for allelopathic impacts on growth and cytogenetic behaviour of barley (Hordeum vulgare) plant.Results revealed a pronounced inhibitory effect of the aqueous extract on seed germination and seedling growth of barley plant.Cytogenetic analysis showed retardation of mitotic activity as well as occurrence of high percentage of chromosomal aberrations in Hordeum plants.Both recorded growth and cytogenetic effects were dose-dependent.At concentration 25%, the lower value of mitotic index (MI=5.09%)and the higher percentage of chromosome abnormalities (CA=35.25%,compared to control (9.1% and 5.25%), respectively.The observed abnormalities were disturbance, stickiness, laggards, vagrants, bridges and micronuclei.The results confirmed the presence of water-soluble allelochemicals in Eucalyptus extract which caused potential phytotoxic, cytotoxic and genotoxic effects in barley.Hence, it is recommended that barley should not be planted close to Eucalyptus trees due to adverse effects on its growth.