ALLELOPATHIC IMPACT OF VOLATILE COMPONENTS FROM EUCALYPTUS ON CROP PLANTS

The effect of crude volatile oils from the leaves of Eucalptus globulus and E. citriodora and the pure terpenes - cineole and limonene from these oils, (in vapour form) was studied on Phaseolus aureus, Lens esculentum, Hordeum vulgare and Avena sativa. The parameters like germination of seeds, seedling growth, values of cell survival, and content of water and chlorophyll of the crops formed the system of bioefficacy study. The allelopathic impact of the oil vapours from the eucalypt tree becomes evident from the negative response of the parameters studied. The impact of the E. citriodora oil vapours compared to that of E. globulus oil or the pure terpenes was seen to be relatively greater in almost all parameters under investigation. A strong reciprocal correlation that exist between the concentration and the seedling growth or the water content of the crops under study supports the dose linked allelopathic phenomenon. It is suggested that oil vapours of Eucalyptus exert their effect through impairing the respiratory as well as photosynthetic ability of the target plants.