01640naa a2200241 a 450000100080000000500110000800800410001902200140006002400390007410000230011324501490013626000090028552008560029465000100115065000250116065000120118565000290119765000230122665300270124965300130127670000250128977300840131420652382017-12-04       2017    bl uuuu     u00u1 u    #d  a1983-40637 a10.1590/1983-40632016v47421282DOI1 aSILVEIRA, P. M. da  aPortable chlorophyll meter can estimate the nitrogen sufficiency index and levels of topdressing nitrogen in common bean.h[electronic resource]  c2017  aThe nitrogen sufficiency index (NSI) obtained by using a portable chlorophyll meter is a practical alternative to evaluate the N levels in plants. This study aimed at determining the appropriate NSI value for leaves of common bean plants, in order to define the need and amount of N to be applied as topdressing, using the Minolta SPAD-502 portable chlorophyll meter. Three field experiments were conducted using a randomized blocks design, with four replications. Nitrogen doses were applied as topdressing and compared with a treatment in which a high dose of N was used as a reference to calculate the NSI, whose value was 95 %. According to the results observed using the chlorophyll meter and the NSI, for each 0.1 percentage point increase in the NSI to reach the adequate level (95 %), it is necessary to apply 1.1-1.5 kg ha-1 of topdressing N.  aBeans  aNitrogen fertilizers  aFeijão  aFertilizante nitrogenado  aPhaseolus vulgaris  aAdubação nitrogenada  aSAPD-5021 aGONZAGA, A. C. de O.  tPesquisa Agropecuária Tropical, Goiâniagv. 47, n. 1, p. 1-6, jan./mar. 2017.