LAUSR

Abstract 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.