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NACL SALINITY-INDUCED CHANGES IN GROWTH, PHOTOSYNTHETIC PROPERTIES, WATER STATUS AND ENZYMATIC ANTIOXIDANT  SYSTEM OF NITRARIA ROBOROWSKII KOM

YAN LU, JIAQIANG LEI AND FANJIANG ZENG*

Abstract: In pot experiments, 1-year-old Nitraria roborowskii Kom plants were planted under control and four levels of NaCl. The plant growth, Na⁺ and K⁺ contents, maximal efficiency of photosystem II photochemistry (F_v/F_m), water potential, antioxidative enzyme activities and contents of photosynthetic pigments, relative water, soluble sugars, proline, hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) in leaves were measured after 90 days of NaCl treatments. N. roborowskii showed tolerance to medium salinity (50 mM NaCl), whereas growth reduction in biomass was observed when ≥ 100 mM NaCl solutions were used for irrigation. Extreme salinity (400 mM NaCl) hardly impacted F_v/F_m, but a marked decreased in chlorophyll content was observed. A gradual decline of the leaf relative water content and water potential with increased NaCl feeding level was accompanied by increased Na⁺ accumulation. The total proline and soluble sugar contents were not significantly affected by low salinity (50 mM NaCl); however, both of these values decreased gradually at high salinities (≥ 100 mM NaCl). MDA and H₂O₂ were not markedly affected at low salinity (50 mM NaCl), but both of these values remarkably accumulated at high salinities (≥ 100 mM NaCl). Superoxide dismutase (SOD), guaiacol peroxidase (POD) and catalase (CAT) presented the same variation trends, first increasing with concentrations of 100, 50 and 100 mM NaCl, respectively, and then decreasing compared to the control, whereas APX increased under all NaCl concentrations.

Key words: Nitraria roborowskii Kom, Chlorophyll content, Halophyte, LIPID peroxidation, Proline, Soluble sugar.

State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, 830011 P.R. China

Cele National Station of Observation and Research for Desert-Grassland Ecosystems, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, 830011 P.R. China

Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, Xinjiang, 830011 P.R. China

^* Corresponding author e-mail:  zengfj@ms.xjb.ac.cn; Tel.: +86-0991-7885439; Fax: +86-0991-7885320