A three-dimensional quantitative structure–activity relationship (3D-QSAR) study was performed on two different chemical series, which have great herbicidal activity, employing comparative molecular field analysis (CoMFA) and comparative molecular similarity indices (CoMSIA) techniques to further investigate the structural requirement for the dicotyledonous stem inhibition. The optimal CoMFA and CoMSIA models obtained for the training set were all statistically significant with cross-validated coefficients (q2) of 0.702, 0.726 and conventional...