The effect of ectomycorrhizal fungi on litter decomposition and phosphorus availability to Pinus koraiensis

Abstract

Mycorrhizal fungi play an important role on litter decomposition and nutrient release, besides nutrient uptake and transfer to host plants. In this study, we evaluated the effects of an ectomycorrhizal (ECM) fungus Suillus grevillei on litter decomposition and the level of phosphorus (P) nutrition in Pinus koraiensis seedlings. Seedlings of annuals were grown under three external P (P0, P20 and P40) levels, with or without S. grevillei inoculation, and with or without leaf litter. We observed that the percentage of mycorrhizal colonization was the highest under P20 among all treatments. Biomass production of seedlings was significantly higher with mycorrhization than without mycorrhization, irrespective of P nutrition. Biomass production was positively correlated to the rate of root mycorrhizal colonization. The amount of P released to soil environment was significantly higher under mycorrhization than under non-mycorrhization irrespective of P nutrition, suggesting that ectomycorrhizal hyphae had transferred from litter-released P and released to host plant. The content of soil P was significantly higher in mycorrhizal rhizosphere than in non-mycorrhizal rhizosphere, and phosphatase activity of ECM-inoculated was higher than that of non-inoculated in the rhizosphere. Meanwhile, we found total Phosphorus concentrations in P. koraiensis seedlings had significant differences between ECM-inoculated and non-inoculated. Our results demonstrate that S. grevillei could promote litter decomposition, litter could promote the development of ectomycorrhizae between S. grevillei and P. koraiensis, ectomycorrhizal fungi could convert P stored in the matrix into an available form to plants and thus promote the growth of both fungi and host plants. Our results also provide implications for an enhanced P biogeochemical cycling in the plant-fungal-soil system.