Effects of salicylic acid and zinc sulfate application on physiological properties, enzymatic activity and quality of peppermint under water stress

The present study was conducted to investigate the effect of salicylic acid and zinc applications on physiological, growth and menthol properties of peppermint (Mentha piperita L.) under water stress conditions in 2019 at Varamin as a split plot factorial arrangement in a randomized complete block design with three replications. The experiment consisted of three factors, including water stress based on evaporation from Class A evaporation pan (50, 70 and 90 mm evaporation from Class A pan) as main plots and salicylic acid foliar application at two levels of 0 and 1 mM and zinc spraying at 0, 2 and 4 g/L in the sub plots. The highest amount of catalase (1.24 Units/mg proteins) was obtained under the application of 4 g Zn per L with salicylic acid and 50 mm evaporation from evaporation pan at. At all levels of drought stress, salicylic acid and zinc sulfate applications increased the catalase content. The main and interaction effects of all treatments except the interaction effects of salicylic acid on ascorbate peroxidase were significant. The results showed that the highest amount of ascorbate peroxidase (1.63 Units/mg protein) was obtained in the treatment of 4 g Zn/L with salicylic acid and in the 90 ml evaporation treatment the evaporation pan. The lowest value ​​(0.53 Units/mg protein) was obtained in the zero zinc and salicylic acid treatments at 50 mm evaporation from the evaporation pan. Zinc sulfate and salicylic acid consumption can be effective in the enzymes activity enhancement, especially catalase, where the highest catalase activity (1.24 unit / mg protein) was obtained in 4 g zinc per liter with salicylic acid and 50 ml evaporation in the evaporation pan, as well as increasing the amount of menthol, which is highly used in the pharmaceutical industry.