Phytotoxicity of Hesperozygis ringens (Benth.) Epling essential oil on Eragrostis plana Nees

Abstract

Natural products derived from native plant species may be an alternative for the control of invasive exotic plants, thus reducing the use of synthetic herbicides. The present study evaluated the phytotoxicity of the essential oil of Hesperozygis ringens (Benth.) Epling, a native plant to the Pampa Biome, as an alternative for the control of Eragrostis plana Nees, an invasive exotic plant from the South Brazilian grasslands. The effect of the essential oil and pulegone, its major component, on germination and initial plant growth was evaluated at concentrations 0 (control), 0.001%, 0.0025%, 0.005%, 0.01%, and 0.02% (v/v). Furthermore, chlorophyll concentration, hydrogen peroxide accumulation, and loss of plasma membrane integrity were evaluated in adult plants at concentrations of 0 (control) and 0.02% for 48 and 60 h. Germination and root/shoot development were negatively affected starting at the concentration of 0.001%, with the most evident results at higher essential oil concentrations. Reduced chlorophyll concentration and tissue damage, due to hydrogen peroxide accumulation as well as loss of plasma membrane integrity, were also observed, thus showing the potential for this essential oil to control E. plana. Pulegone also had inhibitory effects during E. plana germination and seedling formation. Field studies must be conducted to check potential toxic effects on the environment and to determine its applicability as a natural herbicide.