Journal of Experimental Botany, Vol. 54, No. 391, pp. 2331-2342,
October 1, 2003
© 2003 Oxford University Press
N capture by Plantago lanceolata and Brassica napus from organic material: the influence of spatial dispersion, plant competition and an arbuscular mycorrhizal fungus
Received 21 February 2003; Accepted 12 June 2003
Department of Biology, Area 2, The University of York, PO Box 373, York YO10 5YW, UK
* Fax: +44 (0)1904 328510. E-mail: ah29{at}york.ac.uk
This study investigated N capture by Plantago lanceolata L. and Brassica napus L. from complex organic material (dual-labelled with 15N/13C) added either as a thin concentrated layer (discrete patch treatment) or dispersed uniformly with the background sand:soil mix in a 10 cm band (dispersed treatment) when grown in monoculture or in interspecific competition and in the presence or absence of a mycorrhizal inoculum (Glomus mosseae). No 13C enrichments from the organic material were detected in the plant tissues, but 15N enrichments were present. Total plant uptake of N from the organic material on a microcosm basis was not affected by the spatial placement of the organic material, but Plantago monocultures captured less N than the species in interspecific competition (i.e. 23% versus 38% of the N originally added). N capture from Brassica monocultures was no different to either Plantago monocultures or both species in mixture. However, N capture from the organic material by both individual Plantago and Brassica plants was reduced when grown with Brassica plants (by 10-fold and by more than half, respectively). N capture from the organic material was directly related to the estimated root length produced in the sections containing the organic material: the individual that produced the greatest root length captured most N. Strikingly, when the organic material was added as a discrete patch the N captured by Brassica, a non-mycorrhizal species, actually increased when the G. mosseae inoculum was present compared to when G. mosseae was absent (i.e. 35% versus 19% of the N originally added).
Key words: Arbuscular mycorrhizal fungus, Brassica napus L., decomposition, nitrogen capture, organic material, Plantago lanceolata L., root demography.