Assessing the water use efficiency of irrigated fruit crops in semi-arid regions of Brazil using remote sensing and meteorological data

The irrigated perimeter of Jaíba-MG is located in a semi-arid region of Brazil, which makes irrigation practices necessary in order to guarantee agricultural production. This need occurs in the context of limited water resources and, therefore, it is necessary to study ways to optimize water use efficiency (WUE). For this, it is necessary to obtain local and precise estimates of the crop coefficient (K_c) and the reference evapotranspiration (ET₀). The objective of this study was to evaluate the water requirements and WUE of banana, lemon and mango crops in the irrigated perimeter region of Jaíba using satellite images and meteorological data. Landsat 8 satellite images from 2020 and 2021 were used to estimate the local K_c of these crops. Three methodologies for estimating local K_c were adopted: METRIC, NDVI and NDVI 2. The K_c NDVI method stood out when compared with the standard method (FAO Bulletin 56), with RMSEs of 0.11, 0.16 and 0.20 for banana, lemon and mango, respectively, showing the potential of this methodology. The overall average WUE values for banana, lemon and mango crops were 2.19, 1.58 and 1.58 kg m⁻³, respectively. The results could allow important advances in water management for fruit crops under semi-arid conditions.