Ectomycorrhizal
fungus Laccaria bicolor S238N, isolated from a forest soil in central France in 1990s,has
demonstrated
unequivocally an ability to promote pine growth. In the present nursery bed
experiment,the ability of this
ectomycorrhizal fungus to increase growth and P and K uptake of
Douglas Fir seedlings(Zone 22) was examined. Growth of
inoculated seedlings was over twice
(plant height) and three times(biomass) that of non-inoculated ones. Similarly, both the
concentrations and the amounts of P and Kuptake by seedlings were significantly increased by
fungal inoculation, indicating the improvement of P and Knutrition in mycorrhizal seedlings. In
contrast, Al-p in the soils was decreased obviously by plants, especiallyby mycorrhizas,
suggesting utilization of this soil P pool by plants and more efficient Al-P mobilization
bymycorrhizas than by nonmycorrhizas. Moreover, K extracted by 1 mol/L HCl following
consecutive extractionof H_2O and CH_3COONH_4, which may not be plant available, could be
utilized by fungus colonized roots.This could be explained by the release of protons and
oxalate by hypae which leads to replacement of interlayerK in nonexpanded 2:1 clay minerals
and bio-weathering of phyllosilicates.