02060naa a2200313 a 450000100080000000500110000800800410001910000170006024501090007726000090018652011760019565000110137165000160138265000190139865000250141765000200144265000130146265300110147565300140148665300210150070000220152170000230154370000240156670000200159070000200161070000240163070000220165477300700167618995102019-09-23       2011    bl uuuu     u00u1 u    #d1 aLOPES, M. N.  aGas exchange in massai grass under five nitrogen fertilization levels during establishment and regrowth.  c2011  aThe objective of this study was to evaluate gas exchange in the massai grass during establishment and regrowth cycles in a greenhouse, using five nitrogen (N) fertilization levels. A completely randomized split-plot design of five nitrogen levels (0; 150; 300; 450 and 600 mg N?dm-3 of soil) was employed with the N levels as plots, and the cycles (establishment, regrowth 1 and 2) as subplots, evaluated with five replicates. We evaluated leaf transpiration (E), leaf temperature (TFOL), leaf photosynthesis rate (A), leaf carbon dioxide concentration (Ci), stomatal conductance (gs), photosynthesis/transpiration ratio (A/E), photosynthesis/conductance ratio (A/gs), chlorophyll relative index (CRI), and nitrogen sufficiency index (NSI). Growth cycles influenced all physiological characteristics, except for NSI. N fertilization levels affected TFOL, A, CRI and NSI variables, whereas for gs, E, Ci, A/E and A/gs it did not occur. A increased from 6.38 to 10.33 μmol?m-2. s-1, at levels 0 and 600 mg N?dm-3 of soil, respectively. Gas exchange in the massai grass was favored by nitrogen fertilization, since the cycles amended these characteristics of the grass.  aBrazil  aChlorophyll  aPhotosynthesis  aGramínea forrageira  aPanicum maximum  aPastagem  aCeará  aFortaleza  aVariedade Massai1 aLACERDA, C. F. de1 aCÂNDIDO, M. J. D.1 aPOMPEU, R. C. F. F.1 aSILVA, R. G. da1 aLOPES, J. W. B.1 aFERNANDES, F. R. B.1 aBEZERRA, F. M. L.  tRevista Brasileira de Zootecniagv. 40, n. 9, p. 1862-1869, 2011.