(a–d) Effects of soil inoculation on chrysanthemum height (a); thrips (b) and spider mite (c) performance; and chlorogenic acid concentrations in plants (d) in Expt 2. Sterilized soil was inoculated with 10% sterile soil or soil conditioned by grasses (AP, Alopecurus pratensis; FO, Festuca ovina; HL, Holcus lanatus; LP, Lolium perenne) or forbs (AM, Achillea millefolium; GM, Galium mollugo; RA, Rumex acetosella; TM, Tripleurospermum maritimum). Plants were grown in a glasshouse and herbivore performance was assessed in detached leaf assays. Bars represent means ± SE (n = 10 plants; panel (c): four to 10 replicates; estimated means for generalized linear models). These parameters are analyzed for the effect of overall inoculation (inoculated or sterilized), specific soil inocula (eight conditioned soils plus sterilized), and functional group (grasses or forbs, excluding sterilized); asterisks above bars indicate significant differences with the sterilized soil (Dunnett test). ***, P < 0.001; **, P < 0.01; *, P < 0.05; ns, not significant.