Taking the dry powder of Datura stramonium L.leaves as the donor,the soybean seed as the acceptor,we studied the effects of allelochemical stress produced by aqueous leachate on seed germination,young root growth,root hair development,root-tip cell division of soybean by the indoor petri dish with filter paper.The result indicated:In the experiments concentrations scope,the soybean seed germination,young root growth and lateral root growth were inhibited with the dry powder aqueous leachate of D.stramonium L.leaves.And the young root gradually shortened and coarsened and appeared brown spot with the increased stress concentration.In addition,the high-frequency chromosome aberration and micronucleus were induced by allelochemical stress.But the root hair development and root-tip cell division showed a response that they were promoted when lower concentration and inhibited when higher concentration,to wit,the relative lower concentration significantly promoted root hair development and increased the mitotic index while inhibitory effects were observed at higher concentrations of allelochemical stress,the root-tip cell mitotic index obviously to drop.