01910naa a2200265 a 450000100080000000500110000800800410001910000180006024501490007826000090022752011280023665000200136465000370138465000150142165000140143665000140145065000200146465300230148465300080150770000170151570000160153270000200154870000180156877300580158616209631999-01-13       1996    bl uuuu     u00u1 u    #d1 aIBIJBIJEN, J.  aEffect of arbuscular mycorrhizas on uptake of nitrogen by Brachiaria arrecta and Sorghum vulgare from soils labelled for several years with 15N.  c1996  aA pot experiment was conducted under glasshouse conditions to investigate the effect of the inoculation of arbuscular mycorrhizal (AM) fungi on the growth and N uptake of two graminaceous plants: Brachiaria arrecta (Hack. ex. Th. Dur & Schinz) Stent and Sorghum vulgare (Pers.) growing in four fumigated soils which had been labelled for several years with 15N. The four soils had different chemical characteristics, especially in their P availability. The levels of root colonization by AM fungi were inversely related to the P concentration in these soils. Positive responses to AM fungal inoculation were observed for all the yield parameters except in the soil with the highest P availability (40 ug P g-1 soil, extractant Mehlich-1). In the other three soils, AM fungal inoculation of both crops increased N accumulation by between 17 and 46%, but the 15N enrichment of the N absorbed was significantly lower in the mycorrhizal plants than in those not colonized by mycorrhizal fungi. This suggests that some of the N absorbed from the soil by the mycorrhizal roots was derived from N sources other than the mineral N.  anutrient uptake  avesicular arbuscular mycorrhizae  aAbsorção  aMicorriza  aNutriente  aSorghum Vulgare  aBrachiaria arrecta  aVAM1 aURQUIAGA, S.1 aISMAILI, M.1 aALVES, B. J. R.1 aBODDEY, R. M.  tNew Phytologist, Cambridgegv. 133, p. 487-494, 1996.