02765nam a2200493 a 450000100080000000500110000800800410001910000170006024500620007726000510013930000310019049000230022150000680024452015440031265000140185665000120187065000130188265000210189565000130191665000130192965000140194265000150195665000150197165000120198665000160199865000160201465000140203065000110204465000090205565000140206465000150207865000090209365300080210265300360211065300120214665300060215865300080216465300190217265300290219165300060222065300110222665300140223765300200225116221452015-12-14       1990    bl uuuu  m   00u1 u    #d1 aJAMES, E. K.  aOxygen diffusion barriers in the root nodules of legumes.  aDundee: University of Dundee, Fev. 1990.c1990  a150 p.cParte I e parte II  aTese de Doutorado.  aTese de Doutorado. Orientada por: Janet Sprent e Frank Minchin.  aMeasurement of fixation using the acetylene reduction assay is reviewed in light of recent criticism: "flow-through" methods are compared. The effects of acetylene, argon, nitrate and other factors inibiting legume nodule activity are described and related topossible changes in nodule oxigen diffusion resistance. Methods of measuring nodule oxigen diffusion resistance are summarised with particular reference to the method used in the present study. In the first experimental chapter, root nodules of the aquatic legume Neptunia plena are examined using light and electron microscopy. Nodule development differs from conventional indeterminate nodules and has more in common with nodules from "woody" legumes and stem nodules in that cells are infected via infection threads arising from intercellular bacteria. No differences were found between the internal structure of water cultured and vermiculite grown N.plena. The next chapter examines the physiology, growth, nitrogen fixation, oxigen supply and oxigen diffusion resistance of N.plena nodules. No differences were found between water cultured and vermiculite grown nodules for any of these parameters, water cultured nodules were deduced to obtain sufficient oxygen for nitrogen fixation via hollow stems and profuse aerenchyma combined with a considerable lowering of the variable component of nodule diffusion resistance. In addition, non-nitrogenase-linked respiration was maintained at a low value viarelatively reduced root growth and via the production of few, large.....  aacetylene  alegumes  anitrogen  aplant physiology  asalinity  asoybeans  aAcetileno  aFisiologia  aLeguminosa  aMétodo  aNitrogênio  aNodulação  aOxigênio  aPlanta  aRaiz  aRedução  aSalinidade  aSoja  aFBN  aFixacao biologica de nitrogenio  aMethods  aN  aNBF  aNeptunia plena  aNitrogen fixing bacteria  aO  aOxigen  aReduction  aRoot nodulation