Ability of ectomycorrhizal fungus Laccaria bicolor S238N to increase the growth of Douglas fir seedlings and their phosphorus and potassium uptake.

摘要

Ectomycorrhizal fungus Laccaria bicolor S238N, isolated from a forest soil in central France, has demonstrated unequivocally an ability to promote pine [Pinus] growth. In the present nursery bed experiment, the ability of this ectomycorrhizal fungusto increase growth and P and K uptake of Douglas fir [Pseudotsuga menziesii] seedlings (Zone 22) was examined. Growth of inoculated seedlings was over twice (plant height) and three times (biomass) that of non-inoculated seedlings. Similarly, both the concentrations and the amounts of P and K uptake by seedlings were significantly increased by fungal inoculation, indicating the improvement of P and K nutrition in mycorrhizal seedlings. Al-P in soil was decreased by seedlings, especially by those inoculated with mycorrhizas, suggesting utilization of this soil P pool by plants and more efficient Al-P mobilization by mycorrhizal plants than by nonmycorrhizal plants. Moreover, K extracted by 1 mol/litre HCl following consecutive extraction of H2O and CH3COONH4, which may not be plant available, could be utilized by mycorrhizal roots. This could be explained by the release of protons and oxalate by hyphae which leads to replacement of interlayer K in nonexpanded 2:1 clay minerals and bio-weathering of phyllosilicates.