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Table 1 Responses of arbuscular mycorrhizal fungi (extraradical hyphal or spore densities) to various soil organic nitrogen (N) amendments, and the rates of transfer of N from the amendments to the mycorrhizal plants as recorded in previously published experiments (using different experimental set-ups, biological models, and lengths of exposure to the isotopes)

From: Arbuscular mycorrhiza and soil organic nitrogen: network of players and interactions

Identity (form) of N amendment

Quantitative response ratio of AMF hyphal or spore developmenta

Amount of N transferredc

Complex organic N sources (plant biomass, yeast biomass, dead mycelium)

919%1, 292–519%2, 756%4, 55–138%5, 72–341%6, 611%8, − 29 to 341%9, 111–347%18, 186–324%19, 111–4179%27

28.3% (NMd 1.3%)1, (7.9–16.7%)4, 5.0–32% (NM 0.2%)5, 6.0–6.2% (NM 0.2–0.3%6, 26%7, 5.4–9.0% (NM < 0.05%)8, 2.1–3.9% (NM 3.5–6.5%)11, 3.2–5.0% (NM 0.34–1.06%)13, (0.8–7.5%)14, 4.6–8.7%15, 16–25% (NM 2%)16, 15% (NM 5%)19, 4–15%27

Polysaccharides (chitinb, chitosan)

507–729%1, 153–637%2, 23–239%9

22.3% (NM 1.2%)1

Proteins (e.g., albumin)

485%1, 244–760%2

 

Nucleic acids (DNA)

602%1, 233–644%2

 

Amino acids (Gly, Arg)

439–1124%3, 27–187%20

(72%)3, 1.6–5.1%17, 13%28, 0.06–0.1%29

Humic substances (humic acids, fulvic acids)

5.2–158%10, 0.3–203%25

 

Mineral N (NH4+, NO3)

323%1, − 13% to 612%21, − 1.3 to 25%22, 5.5–59%24, 828%26

0.35–4.67%12, 1.9–8.2%17, 2.0–5.8%21, 6% (NM 0%)22, 38.2–39.5% (NM 6.5–15.7%)23, 27.4–49.2% (NM 0.1–0.7%)24, (1–7%)26, 34.5%28, 0.58%29, 12–17% (NM 6–8%)30

  1. aStimulation (positive values) or inhibition (negative values) of AMF mycelial growth and/or sporulation in contrast to control (non-mycorrhizal) treatment, of which the latter is arbitrarily set to 0%. The response of the most common AMF taxa was surveyed (e.g., Glomus hoi, G. aggregatum, Rhizophagus irregularis/syn. G. intraradices/, R. clarus/syn. G. clarum/, Funelliformis mosseae/syn. G. mosseae/, Claroideoglomus claroideum/syn. G. claroideum/)
  2. bCrab-shell chitin or fungal chitin
  3. cAmount of isotopically labeled nitrogen (N) added to the root-free patch and transferred to the plant in a mycorrhizal treatment; numbers in brackets indicate values recorded in the non-mycorrhizal (NM) treatment if preceded with “NM”. Values in brackets without the prefix “NM” indicate values recorded in the mycorrhizal treatment without a significant difference from the NM control treatment, or absence of the NM control treatment from experimental design
  4. dNM—figures for the nonmycorrhizal control treatments
  5. 1Bukovská et al. [15]
  6. 2Bukovská et al. [16]
  7. 3Hodge [48]
  8. 4Hodge [49]
  9. 5Leigh et al. [81]
  10. 6Hodge and Fitter [53]
  11. 7Hodge et al. [58]
  12. 8Barrett et al. [9]
  13. 9Gryndler et al. [43]
  14. 10Gryndler et al. [42]
  15. 11Saia et al. [105]
  16. 12Tanaka and Yano [119]
  17. 13Hodge et al. [56]
  18. 14Hodge et al. [55]
  19. 15Hodge et al. [57]
  20. 16Atul-Nayyar et al. [6]
  21. 17McFarland et al. [89]
  22. 18Tanwar et al. [120]
  23. 19Hodge et al. [52]
  24. 20Allen and Shachar-Hill [2]
  25. 21Fellbaum et al. [27]
  26. 22Johansen et al. [65]
  27. 23Johansen et al. [66]
  28. 24Johansen et al. [67]
  29. 25St. John et al. [116]
  30. 26Hawkins and George [45]
  31. 27Barrett et al. [10]
  32. 28Rains and Bledsoe [102]
  33. 29Cliquet et al. [20]
  34. 30Mäder et al. [85]