Abstract: Under natural conditions,the inhibitory rate(IR)of aqueous extracts from different parts of allelopathic rice accession “PI312777”(planted in paddy soil)in different life stage(3～6 leaf)to the root growth of barnyardgrass were studied.The IR of root exudates at 6 leaf stage of rice planted in paddy soil and in hydroponics and treated by polar resin ADS-21 and nonpolar resin ADS-5 respectively,were tested in the bioassay.The results show that the IR of the aqueous extracts in same rice parts at 5 leaf stage is the highest among 3～6 leaf stages,and the IR of the aqueous extracts from leaves at 5 leaf stage is the strongest.The IR of the root exudates of the rice which are planted in paddy soil to 6 leaf stage is 47.06%,and the IR increases to 64.71% after treated by ADS-21 and decreases to 26.47% after treated by ADS-5;the IR of the root exudates of the rice which are grown in hydroponics to 6 leaf stage is 38.24%,and the IR increases to 58.82% after treated by ADS-21 and decreases to 20.59% after treated by ADS-5.The results implies that the allelopathic effects of the rice root exudates might be mainly resulted from the nonpolar(or weak polar)components,and could be weaken by the polar components.