02043naa a2200229 a 450000100080000000500110000800800410001910000160006024500820007626000090015852013790016765300250154665300200157165300210159165300330161265300140164570000220165970000160168170000150169770000170171277300840172910624882009-02-17       2008    bl uuuu     u00u1 u    #d1 aMARIN, F.R.  aSugarcane crop efficiency in two growing seasons in São Paulo State, Brazil.  c2008  aA conceptual framework for crop production efficiency was derived using thermodynamic efficiency concept, in order to generate a tool for performance evaluation of agricultural systems and to quantify the interference of determining factors on this performance. In Thermodynamics, efficiency is the ratio between the output and input of energy. To establish this relationship in agricultural systems, it was assumed that the input energy is represented by the attainable crop yield, as predicted through simulation models based on environmental variables. The method of FAO's agroecological zones was applied to the assessment of the attainable sugarcane yield, while Instituto Brasileiro de Geografia e Estatística (IBGE) data were used as observed yield. Sugarcane efficiency production in São Paulo state was evaluated in two growing seasons, and its correlation with some physical factors that regulate production was calculated. A strong relationship was identified between crop production efficiency and soil aptitude. This allowed inferring the effect of agribusiness factors on crop production efficiency. The relationships between production efficiency and climatic variables were also quantified and indicated that solar radiation, annual rainfall, water deficiency, and maximum air temperature are the main factors affecting the sugarcane production efficiency.  aAptidão pedológica  aCana-de-açucar  aGeoprocessamento  aModelagem agrometeorológica  aSaccharum1 aLOPES-ASSAD, M.L.1 aASSAD, E.D.1 aVIAN, C.E.1 aSANTOS, M.C.  tPesquisa Agropecuaria Brasileira, Brasiliagv.43, n.11, p.1449-1455, nov. 2008.