Influence of ectomycorrhizal inoculation on Afzelia quanzensis Welw. seedlings in a nutrient-deficient soil

The growth and mineral nutrition of seedlings of one provenance of Afzelia quanzensis Welw. from Kenya, inoculated with two ectomycorrhizal fungi (ECM), one isolate of Scleroderma dictyosporum IR.408 and one isolate of Thelephora sp. ORS.XM002 from Burkina Faso and Senegal, respectively, were assessed in a ECM propagules-free soil at a deficient supply of NPK in a pot experiment, Thelephora sp. ORS.XM002 colonized A. quanzensis seedlings better than S. dictyosporum IR.408. Thus, root dry weight of A. quanzensis was stimulated with Thelephora sp. ORS.XM002. but did not improve any significant total biomass production. P, N, Ca and Mg concentrations in inoculated and non-inoculated A. quanzensis seedlings did not vary significantly. The increase of leaf K concentrations in A. quanzensis seedlings due to ECM inoculation with Thelephora sp. ORS.XM002 or S. dictyosporum IR.408 was not related to plant biomass production. However, the height increments of inoculated plants with S. dictyosporum IR.408 may be nutritional effects, but they are not expressed in terms of dry weight. The hypothesis that non-nutritional effects (e.g. hormonal effects) could explain our experimental results (e.g. stimulation of root dry weight) should also be taken into account. (C) 2002 Elsevier Science B.V. All rights reserved.