(K+) is an essential macronutrient for plants(Marschner, 2012). It is the most abundant inorganic cation andit fulfils vital functions in cell metabolism and extension growth(Leigh and Wyn Jones, 1984; White and Karley, 2010). The opti-mal K+concentration of metabolically active compartments such ascytosol is around 100 mM (Britto and Kronzucker, 2008; White andKarley, 2010).