JOURNAL OF NATURAL RESOURCES ›› 2019, Vol. 34 ›› Issue (12): 2588-2600.doi: 10.31497/zrzyxb.20191209

• Special Forum of "Wetland" • Previous Articles     Next Articles

Effects of groundwater salinities on photosynthesis and water consumption characteristics of Tamarix chinensis in the Yellow River Delta

ZHAO Zi-guo1,2(), ZHAO Feng-juan1,2, XIA Jiang-bao2(), WANG Yue-hai3   

  1. 1. Shandong Provincial Engineering and Technology Research Center for Wild Plant Resources Development and Application of Yellow River Delta, Binzhou University, Binzhou 256603, Shandong, China
    2. Shandong Key Laboratory of Eco-Environmental Science for Yellow River Delta, Binzhou University, Binzhou 256603, Shandong, China
    3. Shandong Academy of Forestry, Jinan 250014, China
  • Received:2019-02-26 Revised:2019-06-22 Online:2019-12-28 Published:2019-12-28

Abstract:

Tamarix chinensis Lour. is a constructive species of the saline-alkali wetland in the Yellow River Delta, and shallow groundwater is the main water source for the growth of T. chinensis in this area. To explore the response mechanism of T. chinensis to groundwater salinity in shallow groundwater area in the Yellow River Delta, parameters of photosynthesis and water consumption were determined under 4 groundwater salinity gradients of fresh (0 g·L-1), brackish (3 g·L-1), saline (8 g·L-1) and salt (20 g·L-1) water at simulated groundwater level of 0.9 m via leaf gas-exchange and stem sap flow (SF) techniques. The results showed that: (1) With increasing groundwater salinity, soil water content, soil salt content and absolute concentration of soil solution increased gradually; (2) Parameters of the max net photosynthetic rate (Pnmax), apparent quantum yield (AQY), light saturation point (LSP), stomatal conductivity (Gs), transpiration rate (Tr), intercellular CO2 concentration (Ci) and stem SF rate increased first and then decreased with the increase of groundwater salinities, reaching the maximum values respectively under brackish groundwater (Gs, AQY, Tr, Ci, and SF rate) and saline groundwater (Pnmax and LSP) treatments, while all values of the above parameters reached the minimum values under salt groundwater treatment; (3) With the increase of groundwater salinity, the water use efficiency (WUE) and stomatal limitation value (Ls) of T. chinensis decreased before increasing, achieving the lowest level under brackish groundwater and the highest under salt groundwater. Under the condition of groundwater depth of 0.9 m, the salinity of groundwater significantly affects the characteristics of soil water and salt contents. The increase of soil water and salt contents, especially the absolute concentration of soil solution, further affects the photosynthetic efficiency and water use strategy of T. chinensis. Moderate groundwater salinity (brackish and saline groundwater) could improve photosynthetic capacity and reduce WUE of T. chinensis, while excessive high groundwater salinity (salt groundwater) would inhibit photosynthesis severely and improve WUE. T. chinensis has high photosynthetic capacity, wide light ecological amplitude and high WUE under saline groundwater conditions at the groundwater level of 0.9 m. This research can be used for the further study of the relationship between plant photosynthetic processes and soil water and salt contents, and can provide theoretical reference for the restoration and reconstruction of soil and water conservation shelterbelts in the Yellow River Delta.

Key words: groundwater salinity, photosynthesis, water use efficiency, transpiration, stem sap flow, Tamarix chinensis