Allelopathic effect of saturated aqueous solution of the volatile oil from Descurainia sophia on seedling growth of test wheat cultivars and the effect on the microbial populations of the soil underneath wheat cultivars (A: Duokang 1; B: Fengyuan 1; C: Zhongmai 1; D: Baomai 1; E: Huaimai 20; F: Zhou 16; G: Zhou 18; H: Wen 10). ► Terpenoids in Descurainia sophia (L.) volatiles inhibited wheat seeds germination. ► Terpenoids in D . sophia volatiles inhibited wheat seedling growth. ► Terpenoids in D . sophia decreased soil microbial counts. ► Responses to the phytotoxicity of D. sophia volatiles were different among cultivars. ► Allelopathic potential of D. sophia volatile compounds can be mediated by soil.