Assessing water use and yield dynamics of high-performing ‘Forelle’ and ‘Packham’s Triumph’ pear orchards under changing climatic conditions in South Africa’s Western Cape Province

As climate change intensifies, the need for accurate quantitative information on crop water use grows, especially in perennial orchards in semi-arid regions. This study investigated water use and yield dynamics in four high-performing commercial pear ( Pyrus communis L.) orchards across different climatic regions of the Western Cape Province, South Africa. A lack of accurate water-use data leads to poor irrigation planning, which undermines the long-term resilience and sustainability of the fruit industry. Sap flow, evapotranspiration (ET), and environmental data were collected over multiple growing seasons per orchard, and these data were used to evaluate a dual-source ET model. Orchard transpiration (T) varied linearly with solar radiation (R 2 ~ 0.82), while the vapour pressure deficit (VPD) had a curvilinear relationship (R 2 ~ 0.71), indicating strong stomatal limitation on T at high VPDs. The model accurately predicted the orchard transpiration (R 2 ~ 0.47–0.83, RMSE ~ ±0.75 to ±0.93 mm/d and Nash-Sutcliffe Efficiency (NSE) 0.30–0.68). Prediction accuracy for orchard ET had R 2 ~ 0.40–0.91, RMSE ~ ±0.72 to ±0.95 mm/d, and NSE ~ 0.29–0.85 under current conditions. Climate data from six GCMs following the RCP8.5 pathway were used as inputs to the ET model. Results showed consistent increases in the orchard floor evaporation (Es), T, and ET fluxes. ET increased by ~ 3.5% between the current period (2020–2030) and the mid-century period (2050–2060). Increases in Es (~4.4%) contributed the most to the rise in ET. In comparison, transpiration increased by a smaller margin (~3.1%) due to the moderating effect of the high VPD on T. Effectively managing orchard floor evaporation is therefore essential to reducing future increases in pear orchard ET under climate change.