Contrasting water sources and water‐use efficiency in coexisting desert plants in two saline‐sodic soils in northwest China

• Published in: Plant biology (Stuttgart, Germany) Germany), 2019-11, Vol.21 (6), p.1150-1158
• Main Authors: Min, X.‐J., Zang, Y.‐X., Sun, W., Ma, J.‐Y., Pfautsch, S.
• Format: Article
• Language: English
• Subjects: Alkalinity; Aquatic plants; Arid lands; Arid regions; Arid zones; Carbon isotopes; Desert plants; Environmental degradation; Environmental stress; Gas exchange; Halophytes; Interspecific; Isotope composition; Isotope Labeling; Isotopes; Leaves; Moisture content; Oxygen; Oxygen isotopes; Photosynthesis; Plant Leaves; Plant species; Poaceae - metabolism; Saline soils; saline‐sodic; Salinity; Salinity effects; Salt tolerance; Salt-Tolerant Plants - metabolism; Salts; Semi arid areas; Semiarid environments; Semiarid lands; Sodic soils; Soil; Soil degradation; Soil layers; Soil management; Soil water; Soils; stable isotopes; Toxicity; Water - metabolism; Water pollution effects; water source; Water use; water‐use efficiency; Xylem
• ISSN: 1435-8603; 1438-8677
• DOI: 10.1111/plb.13028

Soil degradation resulting from various types of salinity is a major environmental problem, especially in arid and semiarid regions. Exploring the water‐related physiological traits of halophytes is useful for understanding the mechanisms of salt tolerance. This knowledge could be used to rehabilitate degraded arid lands. To investigate whether different types of salinity influence the water sources and water‐use efficiency of desert plants (Karelinia caspia, Tamarix hohenackeri, Nitraria sibirica, Phragmites australis, Alhagi sparsifolia, Suaeda microphylla, Kalidium foliatum) in natural environments, we measured leaf gas exchange, leaf carbon and xylem oxygen isotope composition and soil oxygen isotope composition at neutral saline‐sodic site (NSS) and alkaline saline‐sodic site (ASS) in northwest China. The studied plants had different xylem water oxygen isotope compositions (δ18O) and foliar carbon isotope compositions (δ13C), indicating that desert plants coexist through differentiation in water use patterns. Compared to that at the NSS site, the stem water in K. caspia, A. sparsifolia and S. microphylla was depleted in 18O at the ASS site, which indicates that plants can switch to obtain water from deeper soil layers when suffering environmental stress from both salinity and alkalinisation. Alhagi sparsifolia had higher δ13C at the ASS site than at the NSS site, while K. caspia and S. microphylla had lower δ13C, which may have resulted from interspecific differences in plant alkali and salt tolerance ability. Our results suggest that under severe salinity and alkalinity, plants may exploit deeper soil water to avoid ion toxicity resulting from high concentrations of soluble salts in the superficial soil layer. In managed lands, it is vital to select and cultivate different salt‐tolerant or alkali‐tolerant plant species in light of local conditions.