Inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurement
Leaf mineral content was determined according to Mekawy et al. (2018). A leaf blade was dried at 80 oC for 1 day and was crushed by µT-48 (TAITEC, Japan). The crushed samples were decomposed in an acid mixture (HNO3:H2SO4:HClO4= 5:1:2) overnight. Subsequently, the solution was heated at 150oC for 30 min in a heat block. After cooling, the solutions were heated again at 200 oC for 1 h. The above process was continued until the solutions became colorless. The obtained solutions was were for ICP-AES analysis (iCAP6000; Thermo-Fisher, Japan).