Source: sink relationships in potato (Solanum tuberosum) as influenced by potassium chloride or potassium sulphate nutrition

In pot experiments with Solanum tuberosum L. (cv Saturna) the application of KCl as compared to K₂SO₄ delayed tuber development. The solute composition of leaves of the KCl treated plants was significantly lower in K⁺ and NO₃^-, but higher in Mg²⁺, Ca²⁺ and Cl^-. Since the solute potential in the KCl treated plants was more negative and associated with a higher water content, a higher turgor pressure can be assumed. This could explain the enhanced shoot growth observed with KCl. Application of K₂SO₄, on the other hand, accelerated the development of tubers. This might result from a less competitive shoot sink in K₂SO₄ treated plants and a stimulated phloem loading and translocation of assimilates by higher concentrations of leaf-K.