Abstract:Saline-alkali stress is one of the significant abiotic stresses affecting plant growth worldwide. However, the adaptive capacity and physiological response mechanism of Xanthoceras sorbifolia to saline-alkali stress are still poorly understood. In this study, 1-year-old Xanthoceras sorbifolia seedlings were used. We aimed to explore the adaptability of the seedlings to saline-alkali stress, and to reveal the physiological response of hydraulic structure and carbon metabolism of the seedlings to different salinity-alkali stresses. The results showed that:(1) Saline-alkali stress significantly reduced survival rate, plant height, basal diameter, biomass of different parts, predawn water potential, root hydraulic conductivity, photosynthetic rate and stomatal conductance of the seedlings. (2) Along with the increase of saline-alkali stress degree, the contents of NSC in roots, stems and leaves increased first and then decreased. Moreover, the damage degree of saline-alkali stress was significantly higher than that of neutral salt, mirrored as lower survival rate, smaller biomass, lower water potential, root hydraulic conductivity and photosynthetic rate. (3) Saline-alkali stress limited the water absorption ability of root system, and affected the water status of plants, then influenced plant growth and NSC accumulation, even plant survival. The effect of saline-alkali stress was more severe than that of neutral salt. (4) Xanthoceras sorbifolia could adapt to mild saline-alkali environment, while moderate and severe saline-alkali stress would have a great influence on its growth and survival. The physiological response of the seedlings to different types and degrees of saline-alkali stress in terms of water structure and carbon metabolism could provide a basis for the site selection, cultivation range expansion and large-scale development of the Xanthoceras sorbifolia.