Salt absorption capacity and ecological significance of selected Chenopodiaceae halophytes

Objectives The salt accumulation ability of halophytes is one of the most important reference indexes for bioremediation of saline-alkali lands. The ion absorption types and abilities of different halophytes with large biomass were studied to provide a basis for selecting suitable plant materials in saline-alkali soil biological improvement.

Methods Seven Chenopodiaceae halophytes were selected for artificial cultivation experiment in Karamay City, Xinjiang, including Atriplex aucheri, Suaeda altissima, Suaeda salsa, Salicornia europaea, Chenopodium rubrum, Ceratoides latens, and Atriplex canescens. The soil of the test site was silty clay by texture, had an average salt content of 45.57g/kg in the root layer (0‒40 cm), which was categorized as severe saline alkali. The aboveground biomass and the concentrations of Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^– and SO₄^2– were measured at the end of growth.

Results The above-ground dry biomass of the Chenopodiaceae plants were: Atriplex aucheri (35077 kg/hm²) >Suaeda salsa (19507 kg/hm²) > Suaeda altissima (16160 kg/hm²) >Ceratoides latens (12421 kg/hm²) > Atriplex canescens (10798 kg/hm²) > Chenopodium rubrum (10134 kg/hm²) > Salicornia europaea (9576 kg/hm²). In five of the plants - Suaeda altissima, Atriplex aucheri, Suaeda salsa, Salicornia europaea and Chenopodium rubrum, the concentrations of Na⁺, Cl^– and SO₄^2– were significantly higher than K⁺, Ca²⁺ (P<0.05), while in Atriplex canescens and Ceratoides latens, the concentrations of K⁺, Cl^– and Na⁺ were higher than Ca²⁺, Mg²⁺. The total cumulative amount of Na⁺, Cl^–and SO₄^2– were 3835 kg/hm² (Atriplex aucheri) >3145 kg/hm² (Suaeda salsa) >2749 kg/hm² (Salicornia europaea) >2253 kg/hm² (Suaeda altissima) > 615 kg/hm² (Chenopodium rubrum) >367 kg/hm² (Atriplex canescens) > 220 kg/hm²(Ceratoides latens).

Conclusions All the seven halophytes could survive in severe saline-alkali soil and produce ample biomass. However, among them, Atriplex aucheri, Suaeda salsa, Salicornia europaea and Suaeda altissima exhibited strong salt absorption abilities. Suaeda salsa accumulated significantly more SO₄^2– in its aboveground part than other plants, hence was more suitable for the bioremediation of sulfate or chloride-sulfate saline soil. Salicornia europaea had a strong absorption capacity for Cl^–, which rendered it more suitable for bioremediation of chloride saline soil.