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|Title: ||Symbiotic N2-fixation of Pueraria phaseoloides as influenced by arbuscular mycorrhizal fungi and applied phosphate|
|Authors: ||Ahmad Ikram A. J.|
M. N. Sudin
Jensen, E. S.
|Issue Date: ||1994|
|Citation: ||Journal of Natural Rubber Research, 9 (4), p. 258-269|
|Abstract: ||The growth and symbiotic N2-fixation of the plantation legume Pueraria phaseoloides was studied in two P-deficient soils with or without arbuscular mycorrhizas (AM) and applied phosphate. Symbiotic N2-fixation was determined by + the 15N-isotope dilution technique. The soils were a heavy-clay Segamat and sandy Rasau series. In both soils, inoculation with AM fungi or adding phosphate increased shoot growth and N contents significantly despite contamination from indigenous + endophytes in the uninoculated pots. Estimates of the amount of N2-fixed (Ndfa) by P. phaseoloides depended upon the N uptake profiles of the reference plants (Ipomoea batatas and Axonopus compressus) used for the calculations. Symbiotic N2-fixation was + lower in the heavy clay than in the sandy soil. Inoculation with AM-fungi or phosphate supply did not affect the uptake of labelled N (Ndff) or Ndfa in the clay soil whereas both treatments significantly improved Ndff and Ndfa of P. phaseoloides grown in+ the sandy soil. Irrespective of AM fungi inoculation or phosphate supply, Ndfa ranged from -6% to 17% in the clay soil, and from 10%-16% in the sandy soil. Thus more than 80% of the shoot biomass N was derived from soil and fertiliser. The isotope + dilution technique allows determination of N in a crop derived from all sources i.e. from fixation, soils and fertilisers but is subjected to error problems in methodology related to choice of non-fixing reference crops. A declining soil 15N enrichment + and a mismatch in the N uptake patterns between the legume and its reference crop may result in erroneous estimates.|
|Related document: ||http://vitaldoc.lgm.gov.my:8060/vital/access/servi...|
|Appears in Collections:||Publications|
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