Formononetin 7-O-glucoside (ononin), an additional growth inhibitor in soils associated with the weed,Pluchea lanceolata (DC) C.B. Clarke (Asteraceae).

Formononetin 7-O-glucoside (ononin), an isoflavonoid, was isolated from the soils of cultivated areas associated with the perennial weed,Pluchea lanceolata. Aqueous solutions of this compound inhibited significantly root and shoot growth of mustard at 1×10(-4) M, 5×10(-4) M, and 1×10(-3)M. The level of inhibition was similar to that of hesperidin and taxifolin 3-arabinoside, as reported earlier. The potential allelopathic effect of this compound under field conditions is discussed.