02053naa a2200241 a 450000100080000000500110000800800410001910000200006024000710008024500450015126000090019652013610020565000120156665000120157865000100159065000100160065300240161065300090163465300340164370000190167770000180169677300970171418224411999-09-15       1999    bl uuuu     u00u1 u    #d1 aCUNHA, G. R. da  aInfluências do fenômeno Enso sobre a cultura de trigo no Brasil.  aENSO influences on wheat crop in Brazil.  c1999  aThe El Niño-Southern Oscillation (ENSO) phenomenon or just El Niño, as commonly called, influences the climatic behavior in different areas of the world. In the case of Brazil, this phenomenon affects the northern part of the Northeast Region, the eastern Amazon (in the tropical area) and the extra-tropical area of the Southern Region. The climatic variability associated with the ENSO phenomenon phases, especially rainfall anomalies, may be quantified and this information can be effectively used by crop managers to reduce associated risks or to make better use of forthcoming favorable climatic conditions. The objective of this study was to identify the ENSO phases influencing wheat production in Brazil. The impact of these phases on grain yield was based on a historical series of yield data from 1920 to 1997. For 23 El Niño occurrences analyzed at national level, the deviations in wheat yield was negative in 61% of the cases. For 15 La Niña events, positive influences on wheat yields were observed in 73% of the cases. In the 40 neutral years, 55% of the time yield deviations were positive and 45% of the time were negative. Therefore, the ENSO phenomenon influences wheat yield in Brazil. In general, it causes positive impacts in La Niña years and negative impacts in El Niño years, particularly in the Southern part of the country.  aEl Nino  aLa Nina  aClima  aTrigo  aAnomalia climática  aEnso  aÍndice de Oscilação do Sul1 aDALMAGO, G. A.1 aESTEFANEL, V.  tRevista Brasileira de Agrometeorologia, Santa Mariagv. 7, n. 1, p. 127-138, jan./jun. 1999.