Impact of foliar application of copper sulphate and copper nanoparticles on some morpho-physiological traits and essential oil composition of peppermint (Mentha piperita L.)
Introduction: Peppermint (Mentha piperita L.), a member of Lamiaceae family, is an important medicinal plant that has many useful properties. Copper is an essential micronutrient for normal plant growth and metabolism. Objective: The aim of this study was to examine the effects of copper sulphate and copper nanoparticles on morpho-physiological traits and essential oil composition of peppermint. Methods: Seven treatments of copper sulphate and copper nanoparticles in three concentrations (0.5, 1.0 and 1.5 g/l) and control were applied in foliar application three times of the interval of 15 days up to flowering stages of peppermint in Karaj, Iran in 2015. Results: Copper nanoparticles (1.0 g/l) increased chlorophyll content and essential oil percentage of 35% and 20% higher than control, respectively. The copper sulfate (0.5 g/l) increased dry matter yield up to 58% higher than control. The effects of treatments were significant on 17 out of 34 compositions. Copper nanoparticles (1.0 g/l) increased menthol, menthone and menthofuran content up to 15, 25 and 65% higher than in control, respectively. Conclusions: Foliar application of copper sulfate (0.5 g/l) and copper nanoparticles (1.0 g/l) in flowering stage were suggested for increase of dry matter production, essential oil content and composition, respectively.