Ecohydrological processes in water-limited ecosystems are sensitive to deep soil water (DSW), but it remains unclear on how and to what extent deep soil desiccation (DSD) affects these ecohydrological processes, especially during meteorological drought. To address this gap in understanding, we used the Hydrus-2D model - calibrated by continuously observed soil water contents from 0-450 cm soil depth, transpiration (T), and evaporation during the 2018-2021 growing seasons in a dryland apple orchard to determine the ecohydrological response under varying degrees of DSD (> 200 cm) across a range of precipitation levels. The results indicated that deep-rooted apple trees used soil water to a depth of up to 1000 cm, with the proportion of DSW increasing in extremely dry years, causing DSD that inhibited cumulative T and evapotranspiration (ET), which occurred to a greater extent with higher DSD and lower precipitation. Severe deep desiccation and the lack of DSW resources decreased cumulative T by 19.3-23.8% and 37.5-42.5% and ET by 13.0-14.4% and 11.2-23.5%, respectively, across all precipitation amounts in comparison to the cases of no deep desiccation, mild deep desiccation, and moderate deep desiccation. Furthermore, extremely dry years had higher transpiration to evapotranspiration (T/ ET) ratios than extremely wet years, independent of the DSD scenario, and precipitation dominated the T/ET change once DSW was unavailable. These findings enhance our understanding of the impacts of the combination of deep soil drought and meteorological drought on ecohydrological processes in water-limited ecosystems and have significant implications for future vegetation dynamics and water resource management in a changing climate.