The response of chamomile (Matricaria chamomilla L.) plants to soil zinc supply

A pot experiment was conducted to investigate the influence of varying supplies of Zn (50-150-300 mg/kg soil - Orthic Luvisol) on the uptake of Zn by plants, selected productive parameters and production of secondary metabolites in Matricaria chamomilla L., diploid cv. Novbona. Chamomile takes up Zn easily and accumulates it in all its organs. The maximum supply of Zn resulted in an 18-fold increase in chamomile shoots where it reached the level of 271.0 mg/kg dry matter. Such a treatment resulted in a 5-fold increase of Zn in chamomile anthodia (Matricariae flos drug) reaching a level of 159.8 mg/kg dry matter. During cultivation, experimental plants showed no signs indicating an excess of Zn. Of the selected productive parameters, the increasing concentration of Zn in the soil affected significantly only the plant height. A weak, positive, insignificant effect of Zn was observed in the production of the plant biomass. When supplying Zn at a rate of 50 mg/kg soil the biomass of the shoots dry matter increased by 17% and anthodia by 8%, respectively (P > 0.05). However, an additional increase in Zn supply reduced production of anthodia, while the dose of 300 mg Zn/kg soil resulted in a significant, 17% decrease of anthodia yield in comparison with the maximum production achieved with the treatment by 50 mg Zn/kgsoil. The application of Zn into the soil affected only slightly the content of essential oil and proportion of chamazulene, (E)-β-farnesene, and ene-yne-dicycloethers. An increased supply of Zn did not affect the concentration of flavone apigenin and coumarin herniarin in chamomile anthodia. Zn fertilization decreased the accumulation of Cd in chamomile plants; supply of 50 mg Zn/kg soil and caused an decrease in Cd concentration by 10% in shoots (P > 0.05) and by 37% (from 0.280 to 0.176 mg Cd/kg dry matter) in anthodia (P < 0.01), respectively. An additional increase in soil Zn decreased significantly with an accumulation of Cd by 18% (at a dose of 300 mg Zn/kg soil) only in chamomile shoots.