01845naa a2200253 a 450000100080000000500110000800800410001902400410006010000220010124500930012326000090021652010960022565000240132165000170134565000200136265000290138265000100141165300190142165300250144070000190146570000190148470000170150377300710152012037142024-03-06       1981    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1139/b81-2952DOI1 aPEREIRA, P. A. A.  aNitrate reduction and nitrogenase activity in excised corn roots.h[electronic resource]  c1981  aRoot segments obtained from field-grown corn plants were divided into small sections and assayed for acetylene (C2H2) reduction. After overnight preincubation, C2H2 reduction started immediately and linear rates were observed for several hours. Addition of NO3-(1 mM) delayed the start of C2H2 reduction but linear rates followed thereafter. A similar pattern was observed with excised roots inoculated with Azospirillum lipoferum. Addition of malate did not eliminate the NO3- effect. Inoculation with A. lipoferum resulted in relatively large rates of C2H2 reduction and a shorter lag than normal (4 to 8 h). A transient accumulation of NO2- accompanied the disappearance of NO3- and C2H2 reduction started only after all the NO2- had been reduced. A very sizable fraction of the reduced NO3- and NO2- was accounted for as N2O accumulation. Thus, the results provided support for the in situ operation of both N2 fixation and denitrification in A. lipoferum - corn root associations and it is proposed that mature corn roots are able to provide sufficient carbon to support both processes.  aacetylene reduction  aAzospirillum  adenitrification  aFixação de Nitrogênio  aMilho  aDenitrificacao  aReducao de acetileno1 aBALDANI, J. I.1 aDOBEREINER, J.1 aNEYRA, C. A.  tCanadian Journal of Botanygv. 59, n. 12, p. 2445-2449, Dec. 1981.