Root-associated nitrogen-fixing bacteria and their role in the nitrogen nutrition of wheat estimated by 15N isotope dilution

• Published in: Soil biology & biochemistry 1983, Vol.15 (3), p.365-374
• Main Authors: Lethbridge, G., Davidson, M.S.
• Format: Article
• Language: English
• ISSN: 0038-0717; 1879-3428
• DOI: 10.1016/0038-0717(83)90085-8

The ability of two cultivars of spring wheat, Cadet and Rescue, and their reciprocal chromosome substitution lines, C-R5D and R-C5D, to obtain significant quantities of N from atmospheric N 2 was investigated in glasshouse experiments using 125N dilution. The wheat was inoculated with N 2-fixing bacteria, including Azotohacter, Azospirillum, Klebsiella and Bacillus spp, in pure and mixed culture, at N concentrations ranging from 1 to 56 mg N plant −1 (14–168 μg N ml −1), in sand culture and in three soils of differing N content. Root-ussociutcd N 2-fixalion was negligible unless carbohydrate was added to the rooting medium. Atmospheric N 2 was incorporated into wheat roots and translocated to the tops, when plants inoculated with Azotobacter beijerinckii or Azospirillum brasilense sp. 107 were amended with glucose and malate respectively, under monoxenic conditions in sand culture.