Citrus sinensis L. is a sweet orange cultivar of high economic value, traditionally used to alleviate symptoms such as constipation, phlegm accumulation, and fatigue. However, climate change manifesting as prolonged droughts and increasingly severe saltwater intrusion in Vietnam poses a significant challenge to its cultivation. This study was conducted to evaluate the responses of Citrus sinensis to different salinity levels under in vitro tissue culture conditions. Seeds were surface‑sterilized in 0.1 % HgCl₂ for five minutes, rinsed with sterile distilled water, and cultured on MS medium supplemented with NaCl at concentrations of 2–10 g/L. Cultures were maintained for eight weeks, with growth, physiological, and biochemical parameters recorded at two‑week intervals. The results showed that higher salinity significantly reduced plant growth and photosynthetic performance. In contrast, proline content, epidermal thickness, cuticle layer thickness, and lignification of cortical and endodermal cells in roots increased markedly under salt stress. Notably, the thickness of vascular bundle sheath cell walls tended to decrease when NaCl exceeded a certain threshold. These findings provide important scientific evidence for the selection and propagation of salt‑tolerant Cam xoàn lines, thereby contributing to improved production sustainability under global climate change.