title: Arbuscular mycorrhiza infection enhances the growth response of Lolium perenne to elevated atmospheric pCO(2).
abstract: Elevated atmospheric pCO(2) increases the C-availability for plants and thus leads to a comparable increase in plant biomass production and nutrient demand. Arbuscular mycorrhizal fungi (AMF) are considered to play an important role in the nutrient uptake of plants as well as to be a significant C-sink. Therefore, an increased colonization of plant roots by AMF is expected under elevated atmospheric pCO(2). To test these hypotheses, Lolium perenne L. plants were grown from seeds in a growth chamber in pots containing a silica sand/soil mixture for 9 weeks with and without inoculation with Glomus intraradices (Schenck and Smith). The growth response of plants at two different levels of N fertilization (1.5 or 4.5 mM) combined with ambient (35 Pa) and elevated atmospheric pCO(2) (60 Pa) was compared. The inoculation with G. intraradices, the elevated atmospheric pCO(2) and the high N fertilization treatment all led to an increased plant biomass production of 16%, 20% and 49%, respectively. AMF colonization and high N fertilization increased the plant growth response to elevated atmospheric pCO(2); the plant growth response to high N fertilization was also increased by AMF colonization. The root/shoot ratio was reduced by high N fertilization or elevated atmospheric pCO(2), but was not affected by AMF colonization. The unchanged specific leaf area indicated that if AMF colonization represented an increased C-sink, this was fully covered by the plant. Elevated atmospheric pCO(2) strongly increased AMF colonization (60%) while the high N fertilization had a slightly negative effect. AMF colonization neither improved the N nor P nutrition status, but led to an improved total P uptake. The results underline the importance of AMF for the response of grassland ecosystems to elevated atmospheric pCO(2).
authors.affiliation: Institute of Plant Sciences, Swiss Federal Institute of Technology (ETH), 8092 Zurich, Switzerland. hartwig@uni-hohenheim.de
authors.forename: U A
authors.initials: UA
authors.lastname: Hartwig
authors.forename: P
authors.initials: P
authors.lastname: Wittmann
authors.forename: R
authors.initials: R
authors.lastname: Braun
authors.forename: B
authors.initials: B
authors.lastname: Hartwig-Räz
authors.forename: J
authors.initials: J
authors.lastname: Jansa
authors.forename: A
authors.initials: A
authors.lastname: Mozafar
authors.forename: A
authors.initials: A
authors.lastname: Lüscher
authors.forename: A
authors.initials: A
authors.lastname: Leuchtmann
authors.forename: E
authors.initials: E
authors.lastname: Frossard
authors.forename: J
authors.initials: J
authors.lastname: Nösberger
mesh_terms: D018533:Biomass; D002244:Carbon / Q000378:metabolism; D002245:Carbon Dioxide / Q000494:pharmacology*; D017753:Ecosystem; D005658:Fungi / Q000254:growth & development*; D008129:Lolium / Q000187:drug effects / Q000254:growth & development / Q000382:microbiology*; D009584:Nitrogen / Q000378:metabolism / Q000494:pharmacology*; D010758:Phosphorus / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development / Q000382:microbiology*; D018520:Plant Shoots / Q000187:drug effects; D012988:Soil Microbiology; D013559:Symbiosis
chemical_list: D002245:Carbon Dioxide; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen