Abstract: By the methods of bioassay,this paper studied the allelopathic effects of different concentrations root exudates from the eggplants grafted with different stocks and at different growth stages.The results showed that compared with that of own-rooted eggplant,the root exudates from grafted eggplants promoted the seed germination and seedling growth of eggplants,and,in comparing with the control (water),they increased the germination rate and plant height by 29.1% and 37.1%,respectively.The seed germination and root length of eggplants was increased at lower concentrations root exudates,but decreased at higher concentrations.The germination rate was increased up to 50% above control at 0.04 g·ml^-1,and the inhibition of root length was up to 30.3% at 0.24 g·ml^-1.The promotion effect of the root exudates from late growth stage grafted eggplants on seed germination was less than that from other growth stage grafted eggplants. Own-rooted eggplant had an intensified inhibitory effect at its late growth stage.Grafting was one of the effective methods for relieving the continuous cropping obstacles caused by autotoxicity.

Key words: Organicall modified clay, Prorocentrum donghaiense, Red tide