Evapotranspiração, coeficiente de cultivo e modelagem agrometeorológica da cebola cultivada no semiárido nordestino.

Abstract

This study determined the water use, the crop coefficient, besides calibrating and validating the FAO AquaCrop version 5.0 model for the variety of the onion "IPA 11" in the northeastern semi-arid region. Two field experiments were carried out at EstAgro, in the city of Campina Grande/PB, for the rainy and dry season of the region in 2018, using the treatments of 100, 75, 50 and 25% of the reference evapotranspiration (ETo). The results shows the crop evapotranspiration (ETc) was determined by the soil water balance method, which presented mean values of 3.6 and 4.7 mm/day for the first and second cycle, respectively. The simulations of biomass (B) and dry yield (Y) of the crop through AquaCrop generated results for the different irrigation treatments that were calibrated and validated, using climate, soil, crop and management parameters. The performance of the model was evaluated using the statistical indicators: root mean square error (RMSE), root mean squared error normalized (RMSEN), Nash-Sutcliffe efficiency (EF), Willmontt's index (d) and the Prediction error (Pe). The values found were satisfactory in both experiments, indicating applicability of the model. It was also verified that the recommended irrigation depth for the onion cultivated under the conditions of this experiment is 100% of the ETo.