Increased uptake of anions by plants with vesicular-arbuscular mycorrhizas

In two field experiments sown in 1982 to test the effect of vesicular-arbuscular mycorrhizas (VAM) on growth and phosphorus nutrition of (i) spring wheat and spring barley, (ii) winter wheat and winter barley, we measured the concentrations of the major cations (K⁺, Ca²⁺, Mg²⁺ and Na⁺) and anions (Cl⁻, SO₄²⁻, H₂PO₄⁻ and NO₃⁻) in shoot tissue. In all cases the sum of the anion concentrations (ϵA) was increased strongly by mycorrhizal infection but not by Ñ additions, confirming earlier observations² on spring wheat. The concentration of total cations (ϵC) was generally reduced by P additions, hence P and VAM both reduced the cation excess (ϵC — ϵA) but by different mechanisms. These results suggest that increased uptake of anions by plants with VAM may be a general phenomenom which would have important implications for the elemental composition of crops. The effect may also be manifested by other types of mycorrhizal association.