The study tested the effect of vanadyl (IV) sulfate (VOSO4) on the production of flavonoids in the callus and suspension culture of Ononis arvensis L. (Fabaceae). This substance proved to be a good abiotic elicitor for an increase in the production of secondary substances (flavonoids) in the culture of Ononis arvensis L. in vitro. The maximal increase in the formation of flavonoids took place in the callus culture after 24-hour elicitation with VOSO4 in a concentration of 1.227 .10-4 mol/l by 313 % in comparison with the control and in the suspension culture in a concentration of 1.227 .10-6 mol/l after 48-hour action of the elicitor by 485 % in comparison with the control.

        Key words: Ononis arvensis – callus and suspension culture – flavonoids – vanadyl (IV) sulfate