This paper aimed to support the rational water management of lemon orchards, under different irrigation systems in semi-arid environments. The SAFER (Simple Algorithm for Evapotranspiration Retrieving) algorithm was applied to Landsat 8 images for energy balance and irrigation performance assessments in a reference semi-arid region of Southeast Brazil. The analyses involved six commercial farms with orchards, under drip, micro sprinkler, and pivot irrigation systems. Actual evapotranspiration (ET) averaged respectively 2.7 mm d⁻¹, 2.9 mm d⁻¹, and 3.7 mm d⁻¹, for drip, micro sprinkler, and pivot irrigation systems, respectively, with the evaporative fraction (latent heat flux by the available energy) reaching above 1.00 for localized irrigation (drip and micro sprinkler), and 1.30 for pivots, during the phenological stages from fruit growth to harvest peaks. Pivot irrigation systems were not recommended due to large water consumption for soil evaporation, thus, for drip and micro sprinkler irrigated orchards, crop coefficient curves allowed the estimation of the lemon crop water requirements. By adding data on reference evapotranspiration and productivity, irrigation performance indicators were computed for the performance assessments. Drip irrigation systems promoted better water productivity levels being recommended together with deficit irrigation strategies that allow for obtaining reasonable lemon yields while saving water in semi-arid regions.

本文旨在支持在半干旱环境下不同灌溉系统下柠檬园的合理水管理。将SAFER（用于蒸发蒸腾的简单算法）算法应用于Landsat 8图像，以在巴西东南部的参考半干旱地区进行能量平衡和灌溉性能评估。分析涉及六个有果园的商业农场，这些果园具有滴灌，微型洒水和枢轴灌溉系统。实际蒸散量（ET）平均分别2.7毫米d ^-1，2.9毫米d ^-1，和3.7毫米d ^-1，分别从滴灌，微喷和枢轴灌溉系统开始，在物候阶段，蒸发分数（潜热通量，可用能量）达到1.00以上（局部灌溉（滴灌和微喷）），枢轴为1.30以上。果实生长达到高峰。由于土壤蒸发会消耗大量水，因此不建议使用枢轴灌溉系统，因此，对于滴灌和微型洒水灌溉的果园，作物系数曲线可以估算柠檬作物的需水量。通过增加参考蒸散量和生产力的数据，计算了灌溉绩效指标以进行绩效评估。