Nutrient Supply Rate and Mycorrhizal Colonization Control Patterns of Element Distribution in Ectomycorrhizal Pine

Abstract

Ectomycorrhizal fungi may provide plants access to nonexchangeable nutrients. We measured nutrients (potassium, calcium, magnesium, manganese, iron, and aluminum) in roots and foliage in nonmycorrhizal and ectomycorrhizal Pinus sylvestris cultured in perlite at two nutrient supply levels. We also measured nutrients in perlite leachates from abiotic experiments using hydrochloric or oxalic acid at pH2-4. Twenty-one percent more potassium and 30% more calcium accumulated in nonmycorrhizal plants than in ectomycorrhizal plants, presumably because of nutrient sequestration in extraradical fungal biomass. Plants at low nutrient supply accumulated 22% more potassium and 23% more calcium than at high nutrient supply, presumably because of additional mobilization of nutrients from perlite by plant and fungal acids. Significantly more leaching at pH2 with oxalic than with hydrochloric acid occurred, probably caused by enhanced ligand-mediated dissolution with oxalic acid. Leaching of minerals by organic acids may enhance plant nutrient supply, particularly from microsites of low pH.