Allelopathic effects of leaf litter and live roots exudates of Eucalyptus species on crops

The allelopathic effects of extracts of leaf litter and live roots of three Eucalyptus species [ Eucalyptus urophylla Blake (Myrtaceae), Eucalyptus citriodora Hook. and Eucalyptus camaldulensis Dehnh] were determined on the following crops: radish [ Raphanus raphanistrum var. sativus L. G. Beck, Brassicaceae), cucumber (Cucumis sativus L., Cucurbitaceae), and Chinese cabbage ( Brassica rapa var. glabra Regel, Brassicaceae)]. The extracts of leaf litter and live roots were inhibitory or stimulatory to test species. However, the effects of leaf litter extracts at lower concentrations were similar to natural concentration in fields and were more pronounced than live roots. When litterfall were removed, Chinese cabbage should be a good candidate crop grown under Eucalyptus urophylla and cucumber should be a good candidate crop grown under all tested Eucalyptus species in the tree-crop agroforestry systems .