Inhibitory effect of an emulsion of Nepeta rtanjensis essential oil on Amaranthus retroflexus seed germination

Abstract

The widespread use of pesticides and their adverse eff ects (through soil pollution, pest resistance, etc.) have created a need for turning to natural resources in search for new/old methods of pest control. Essential oils belong to a group of volatile secondary metabolites of plants which aff ect the growth and development of surrounding plants by spreading around in gaseous state. The eff ect of an essential oil emulsion of Nepeta rtanjensis Diklić et Milojević on seed germination of redroot pigweed (Amaranthus retrofl exus L.) was tested in this experiment. Dynamic and total germination of seeds were evaluated after fi ve concentrations of the essential oil emulsion (ranging 0.006-0.1 %) were applied. Before treatment, seeds were stratifi ed for two and a half weeks at 3±2 °C. The experiment was carried out in Petri dishes under constant temperature of 30±1 °C. Seeds were germinated in the dark over the initial 24 h and then illuminated during 10 min counting sessions at intervals of 1-3 days. Germination of A. retrofl exus seeds was inhibited after all tested treatments. The fi nal percentage of germinated seeds treated with the lowest concentration (0.006%) of N. rtanjensis essential oil did not deviate signifi cantly from data in the control groups but inhibition through germination dynamic was noted. Seeds did not germinate at all after receiving the highest concentration (0.1%) of the essential oil.