Abstract: Aims Leaf and root hydraulic traits play an important role in the hydraulic architecture of trees, but the differences between leaf and root turgor loss point (TLP) and their relationship with the stomatal closure point (Ψclose) are not fully understood. And the potential relationship between leaf and root morphological characteristics, non-structural carbohydrate (NSC) content and turgor loss traits among different tree species is not clear. Methods Five coniferous tree species and seven broad-leaved tree species common in the loess gully region were selected as the research objects, and the differences in their TLP, Ψclose and NSC contents of leaves and fine roots were compared, and the relationship between leaf and fine root morphology and TLP was analyzed. Important findings The TLP and water capacity of leaf and fine root of coniferous tree species were significantly lower than those of broad-leaved species, and the specific leaf area and specific root length of coniferous species were also significantly lower than those of broad-leaved tree species. The Ψclose of coniferous tree species was significantly higher than that of broad-leaved tree species, and the soluble sugar content and leaf NSC content of leaf and fine roots of coniferous tree species were significantly higher than those of broad-leaved tree species. The leaf TLP of all tree species was significantly lower than that of fine roots. There were significant correlations between specific leaf area and leaf TLP, specific root length and fine root TLP, and leaf TLP and fine root TLP in all tree species. The results suggested that conifer species had stronger ability to maintain leaf and fine root turgor pressure, and their stomata were more sensitive, which made coniferous species more tolerant to the arid and water-scarce environment in this area. And the results of this study also suggested that there were differences in the relationship between turgor loss points and stomatal closure points between coniferous and broad-leaved tree species.

Key words: turgor loss point, stomatal adjustment, fine root, leaf, non-structural carbohydrate content