The allelopathic effects of Eucalyptus grandis leaves with different status on morphology and resistance physiology of Raphanus sativus seedlings (receiver plant) were studied.The seedling was breed with perlite as cultivated substrate.Different status of E.grandis leaves including tender leaves (T₁),old leaves (T₂),the leaf litter from ground surface in a 4-year-old plantation (T₃) and the half-decomposed leaf litter (T₄) were chosen,and their aqueous extracts were prepared by soaking different amount (30 g,15 g and 7.5 g,dry weight) of leaves in equal amount of water (900 mL),resulting into four concentrations for each kind of leaves.The distilled water was used as the control (CK).The results were as follows:(1)The extracts of E.grandis leaves in different status significantly inhibited the root length of R.sativus,with the extract of tender leaves having the strongest inhibition and the half-decomposed leaf litter showing the weakest inhibition.(2)The activities of catalase (CAT) and peroxidase (POD) in R.sativus were elevated treated with all levels of all extracts.The activity of superoxide dismutase (SOD) in R.sativus was increased by exposure to the tender leaves (T₁) extract regardless of the concentration,and to other extracts under the high concentration,while the activity of SOD decreased when exposed to other extracts of low concentrations.(3)The content of malondialdehyde (MDA) decreased under leaf extracts with low concentrations,while increased under those with high concentrations.(4)The soluble sugar (SS) content of the receiver plant was higher in the presence of the extract of tender leaves regardless of the concentrations,compared to CK,while with the increasing extract concentration of old leaves and half-decomposed leaves.SS content presented a decrease trend after an increase.Soluble protein (SP) content increased with the increasing concentration of all kinds of extracts,and the differences became significant under all concentrations for leaves T₂ and T₃ when compared to CK.On the whole,the aqueous extracts of different status leaves of E.grandis showed remarkable allelopathic effects on the growth and resistance physiology of R.sativus seedlings,with the extract of tender leaves exhibiting the strongest effect,followed by the old leaves and the leaf litter from ground surface,and then the half-decomposed leaf litter.