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Journal of Desert Research ›› 2018, Vol. 38 ›› Issue (3): 568-577.DOI: 10.7522/j.issn.1000-694X.2017.00099

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Photosynthetic Response Characteristics and Water Use Efficiency of Tamarix chinensis under Water and Salt Gradients in Wetlands

Meng Yangyang1,2, Liu Bing1, Liu Chan1,2   

  1. 1. Linze Inland River Basin Research Station/Key Laboratory of Ecohydrology of Inland River Basin, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2017-04-21 Revised:2017-09-25 Online:2018-05-20 Published:2018-11-06

Abstract: Photosynthetic response characteristics and water use efficiency can further understand the adaptive mechanism of Tamarix chinensis on water and salt stress and provide scientific guidance for the improvement and management of salinization in desert oasis wetland. This project took the desert oasis wetlands as the subject, photosynthetic parameters and its response to light intensity of T. chinensis under water and salt gradients were measured by Li-6400 photosynthetic instrument, to study the influencing mechanism of water and salt gradients on the photosynthesis and water use efficiency of plants in desert oasis wetlands. The results were as follows:The diurnal variation in net photosynthetic rate (Pn) of T. chinensis in desert oasis wetlands showed two peaks. Compared with main peaks, the secondary peaks of Pn in riparian shrub wetland, salt marsh and oasis grassland wetland decreased by 19%, 8.5% and 11.2%, respectively. Transpiration rate (Tr) showed a single peak. Under the same water and salt environment, Pn and water use efficiency (WUE) of T. chinensis rose rapidly and then to a flat with the increase of photosynthetically active radiation (PAR). But Tr was not sensitive to the enhancement of PAR. The maximum net photosynthetic rate, the light saturation point and the apparent quantum efficiency of T. chinensis in salt marsh were the largest, and its light compensation point was the smallest. The light saturation point of T. chinensis in wetlands was in the range of 512.67-1 790 μmol·m-2·s-1, and the light compensation point was in the range of 16.28-19.23 μmol·m-2·s-1. Moderate water and salt content can promote photosynthesis. When water and salt content is too high or too low, it will inhibit the photosynthetic rate. The lower the salt content is, the wider the range of light intensity adaptability of T. chinensis in desert oasis wetlands. Moderate decrease of water content is beneficial to the improvement of water use efficiency.

Key words: photosynthetic parameters, water use efficiency, water and salt gradients, Tamarix chinensis, desert oasis wetland

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