Allelopathic effects of orange (Citrus sinensis L.) peel essential oil

crop weeds are the main problem in agriculture, causing a worldwide annual loss of about us$95 billion. the principal method for control is the use of synthetic herbicides. the continued use of these products increases crop costs, reduces crop quality, and leaves toxic residues in the environment, which are a threat to human and livestock health. therefore, there is a demand for environmentally friendly methods of weed control. the use of allelopathic compounds from crop residues is an alternative. orange is one of the biggest crops in the world, and its cultivation generates large amounts of residues. there is strong evidence of bioactivity in orange peel essential oil. therefore, the objective in this work was to verify the allelopathic proprieties of this oil. we extracted the oil from the peels of recently discarded oranges using water vapor flow with a clevenger extractor, and tested it against the growth of euphorbia heterophylla l. and ipomoea grandifolia (dammer) o'donell seedlings when placed in contact with the oil vapor. the results were both quantitative and qualitative in the inhibition of the seedlings.