Fig. 2

Absorption kinetics curve of K⁺ in tobacco roots under different treatments. +K represents normal potassium levels (5 mmol L^− 1) and -K represents potassium starvation (0.5 mmol L^− 1). Ungrafted tobacco W (Wufeng No.2) and Y (Yunyan 87), and grafted tobacco Y/W (Y grafted onto W) and W/Y (W grafted onto Y) during the 20 h nutrient depletion test