Critical Zn concentration for essential oil yield and menthol concentration of Japanese mint

The effect of different concentrations of Zn nutrient application on Japanese mint (Mentha arvensis L.) was studied under glasshouse conditions. Zn application stimulated the dry matter production, essential oil concentration and menthol concentration of Japanese mint. Zn supplies of 0.05µg ml^–1 were required for maximum responses in dry matter yield and oil concentration. Significantly positive interrelationships were observed among fresh herb yield, dry matter yield and menthol concentration in the oil. Graphical analyses of Cate and Nelson model indicated the critical Zn concentration in leaves to be 28µg g^–1 on a dry matter basis and in the solution culture 0.0475µg ml^–1 on the basis of Zn concentration in leaves.