Potassium induced suppression of magnesium uptake and translocation is limited in oat (Avena sativa L.)

The main cause of magnesium (Mg²⁺) deficiency in plants is its competition with potassium (K⁺). Besides uptake antagonism, previous studies also suggested that high [K⁺] inhibits root-shoot translocation of Mg²⁺. In this study on oat, root elemental analysis revealed an evident but, with further increasing K⁺/Mg²⁺ ratio, limited suppression of Mg²⁺ uptake. In contrast, shoot [Mg²⁺] showed little or no reduction. This indicated a translocation synergism, as the suppression of the root [Mg²⁺] by K⁺ was counterbalanced. Oat thus provides new insights and raises new questions about the interactions of K⁺/Mg²⁺, in particular on the role of specific Mg²⁺ transporters. A better understanding of this interaction may help to counter the worldwide Mg deficiency more effectively.