Mycorrhizal occurrence and responsiveness of tall fescue and wheatgrass are affected by the source of phosphorus fertilizer and fungal inoculation

Abstract

We assessed colonization and mycorrhizal growth responses (MR) of wheatgrass and tall fescue growing with and without indigenous soil microorganisms (from Argentinean Pampas) as affected for inoculation with the non-indigenous arbuscular mycorrhizal fungi (AMF) Acaulospora longula or Glomus claroideum and for fertilization with superphosphate (SP) or rock phosphate (RP). Inoculation increased growth, P uptake and MR in plants growing without indigenous microorganisms. The highest MR was determined in non-fertilized tall fescue plants inoculated with G. claroideum. When inoculation and RP were added together to the fumigated soil, plant growth, mycorrhiza and MR were significantly stimulated over the single treatments. When plants were grown in non-fumigated soil, no treatment effects were detected. The introduction of G. claroideum or A. longula under like-field conditions would not cause plant growth increments under field conditions. Emphasis could be put to select an effective indigenous AMF, and reinforcing the mycorrhizal population in soils supplied with RP.