Determining optimum sowing date for maize using modelling approach.

The objective of this study was to determine the optimum sowing date for maize at Santo Antonio de Goias, GO, Brazil. To optimize solar radiation and precipitation during the maize sowing period (from October to December) it was used the crop model CEREAL06 from Ecotrop plataform. To mimic the conditions of region, two scenarios were created: a) no restriction to root development (1.0 m effective root depth) and b) restrictions to root development (Al toxic in the subsoil - 0.5 m effective root depth). The crop model was run based on the climate historical date (22 years of daily data for precipitation, solar radiation, maximum and minimum temperature, maximum and minimum relative humidity, and wind speed) collected at Embrapa Rice & Beans weather station. Six different sowing dates (15/10, 01/11, 15/11, 1/12, 15/12, and 31/12) were taken into account. The decision criterions used to determine the optimum sowing date were the variability, comparison of exceedance probability and mean variation for yield and the averaged index stress factor for the reproductive period. The results obtained showed that the optimum sowing date for both scenarios was 15-Nov.