Contribution of arbuscular mycorrhizal fungi to plant inorganic and organic nitrogen in-situ uptake in grasslands

VAIERETTI, M.V.; WILKINSON, A.; HILL, P.W.; JOHNSON, D.; JONES, D.L.; BARDGETT, R.D.

Buenos Aires

Simposio; 32nd New Phytologist Symposium Plant interactions with other organisms: molecules, ecology and evolution; 2013

New Phytologist

In ecosystems strongly limited by nitrogen (N), such as low productivity grasslands, plants can acquire significant amount of organic N directly from the soil. It has been suggested that arbuscular mycorrhizal fungi (AMF) present in those low productivity grasslands might play an important role in the transfer of organic-N to host plants. We performed a field experiment, in Agrostis-Festuca grasslands (Wales, UK), using a mesh core system that restrict or allow fungal hyphal ingrowth (-AMF and +AMF, respectively). We injected in-situ inorganic (NH4+ and NO3-) and organic (amino acid and peptide) N solutions labelled with stable isotopes (13C/15N) to quantify N transfer via AMF networks from cores to vegetation roots and shoots after 2.5 hours of application. Only small amounts of the added inorganic and organic 15N were recovered in the plant material. We did not observe significant differences in the different N forms uptake between ?AMF and +AMF treatments. Although we did find that part of the added amino acid-15N was taken up and transferred in intact form from AMF hyphae to the surrounding mycorrhizal root tissues, our results suggest that AMF do not play an important role in host plant N uptake in these low productivity grasslands.