Objective To increase the ultimate yield of periplocin in Periploca sepium adventitious root cultures by a two-stage culture based on nitrogen source.Methods Firstly,the effects of nitrogen source(NH-)at different ratios and different total initial nitrogen amounts on the accumulation of biomass and secondary metabolites in adventitious root cultures of P sepium were investigated,and growth and production media for the two-stage culture based on the above results were established.Results The highest biomass and periplocin content were obtained in the culture medium of 15 mmol/L total nitrogen amount with NH