02593nam a2200397 a 450000100080000000500110000800800410001910000180006024500890007826001470016752015310031465000110184565000130185665000120186965000130188165000090189465000160190365000170191965000100193665000160194665000150196265000090197765000130198665300110199965300140201065300100202465300150203465300140204965300150206370000170207870000180209570000240211370000210213770000190215870000180217714773002018-06-11       1997    bl uuuu     u00u1 u    #d1 aSANTOS, M. X.  aDrought and low N status limiting maize production in Brazil.h[electronic resource]  aIn: SYMPOSIUM OF DEVELOPPING DROUGHT AND LOW N-TOLERANCE MAIZE, 1996, El Batan, Mexico. Proceedings... El Batan: CIMMYT, 1997. p. 20-23.c1997  aThe Brazilian territory has an area of approximately 8,5 million km2, which is divided into five main regions with particular characteristics related to average climitaic conditions and natural soil fertility. Climatic variations may be very accentuated within each particular region, but a common feature is the irregular distribution of rains, which causes droughts of variable intensities. Maize is an important crop in most Brazilian regions, occupying approximately 13 million ha and producing annually 28-30 million tons of grain. It has been estimated that drought problems, depending on year intensity, reduce maize production by 14% to 28%. Another limiting factor for maize production in Brazil is the low natural fertility of the soils, especially in nutrients like phosphorus and nitrogen (N). It has been estimated that 80% of the soils in Brazil are deficient in N. Although fertilization is a common solution to this problem, its high costs make this option inaccessible to many farmers. The amount of supplemental N applied to maize in Brazil is low (36 kg N/ha), and of this only 50% to 60% is utilized by the crop. Considering that low N availability and drought are severe constraints to maize crop in Brazil, the National Maize and Sorghum Research Center (CNPMS/EMBRAPA) has initiated breeding programs aimed at the development of germplasm that performs more efficienctly under these two limiting conditions. Several genotypes have been developed on the basis of anthesis-silking interval selection (...)  aBrazil  abreeding  adrought  anitrogen  asoil  aFertilidade  aMelhoramento  aMilho  aNitrogênio  aProdução  aSeca  aZea Mays  aBrasil  aFertility  aMaize  aProduction  aTolerance  aTolerancia1 aLOPES, M. A.1 aCOELHO, A. M.1 aGUIMARAES, P. E. O.1 aPARENTONI, S. N.1 aGAMA, E. E. G.1 aFRANCA, G. E.