Reciprocal N (15NH4 +or15NO3 -) Transfer between non N2-Fixing Eucalyptus maculata and N2-Fixing Casuarina cunninghamiana Linked by the Ectomycorrhizal Fungus Pisolithus sp

• Two-way N transfers mediated by Pisolithus sp. were examined by excluding root contact and supplying15NH4 +or15NO3 -to 6-month-old Eucalyptus maculata or Casuarina cunninghamiana grown in two-chambered-pots separated by 37 μm screens. • Mycorrhizal colonization was 35% in Eucalyptus and 66% in Cas...

Full description

Saved in:
Bibliographic Details
Published in:The New phytologist 2004-09, Vol.163 (3), p.629-640
Main Authors: He, Xinhua, Critchley, Christa, Ng, Hock, Bledsoe, Caroline
Format: Article
Language:English
Subjects:
Atoms
Frankia
Hyphae
Mycorrhizal fungi
Mycorrhizas
Nitrogen
Nodules
Plant roots
Plants
Seedlings
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:• Two-way N transfers mediated by Pisolithus sp. were examined by excluding root contact and supplying15NH4 +or15NO3 -to 6-month-old Eucalyptus maculata or Casuarina cunninghamiana grown in two-chambered-pots separated by 37 μm screens. • Mycorrhizal colonization was 35% in Eucalyptus and 66% in Casuarina (c. 29% N2-fixation). Using an environmental scanning electron microscope, living hyphae were observed to interconnect Eucalyptus and Casuarina. Biomass and N accumulation was greatest in nodulated mycorrhizal Casuarina/mycorrhizal Eucalyptus pairs, less in nonnodulated mycorrhizal Casuarina/mycorrhizal Eucalyptus pairs, and least in nonnodulated nonmycorrhizal Casuarina/nonmycorrhizal Eucalyptus pairs. • In nonnodulated mycorrhizal pairs, N transfers to Eucalyptus or to Casuarina were similar (2.4-4.1 mg per plant in either direction) and were 2.6-4.0 times greater than in nonnodulated nonmycorrhizal pairs. In nodulated mycorrhizal pairs, N transfers were greater to Eucalyptus (5-7 times) and to Casuarina (12-18 times) than in nonnodulated mycorrhizal pairs. Net transfer to Eucalyptus or to Casuarina was low in both nonnodulated nonmycorrhizal (< 0.7 mg per plant) and nonnodulated mycorrhizal pairs (< 1.1 mg per plant). In nodulated mycorrhizal pairs, net transfer to Casuarina was 26.0 mg per plant. • The amount and direction of two-way mycorrhiza-mediated N transfer was increased by the presence of Pisolithus sp. and Frankia, resulting in a net N transfer from low-N-demanding Eucalyptus to high-N-demanding Casuarina.
ISSN:0028-646X
1469-8137