Abstract: Flavonoid-stimulated rhizobia were used to inoculate the seedling roots of oilseed rape, making the rhizobia intrude into the roots, form para-nodules and fix nitrogen. The results show that rhizobia stimulated by flavonoid could effectively invade root cells and form para-nodules containing rhizobia, with nodulation rate of 100%. The strains isolated from para-nodules of oilseed rape could successfully re-inoculated to original host. The determination of antiserum show that the strains could agglutinate with test rhizobia. Electron microscopic observation shows that the cells of para-nodule were full of bacteria. The activity of N-fixing enzyme in para-nodules determined by acetylene reduction method was 142.01 nmol C₂H₄·g^-1·h^-1.

Key words: Flavonoid, Rhizobium, Oilseed rape