The effects of density and salinity on shoot biomass and ion accumulation in five inland halophytic species

Abstract

Five inland halophytes, Atriplex prostrata, Hordeum jubatum, Salicornia europaea, Spergularia marina, and Suaeda calceoliformis, were grown in controlled laboratory conditions under three salinity treatments (0.5, 1.5, and 2.5% NaCl) and three density treatments (5, 15, and 30 plants∙100 cm−2) to determine the effects of salinity and density on survival, growth, and ion accumulation. The more salt sensitive species, A. prostrata and H. jubatum, had significant (P < 0.05) density-dependent mortality. Density significantly reduced biomass production for all species, except for H. jubatum in the high-salinity treatment. Succulence in Suaeda calceoliformis shoots increased in the high-salinity treatment, but H. jubatum plants were desiccated at the time of harvest. The ash, sodium, and chloride contents of shoots increased with salinity for all species. Sodium and Cl− ion contents for all species –treatment combinations were an order of magnitude higher than that of Mg2+, Ca2+, and K. Although A. prostrata, Salicornia europaea, and Suaeda calceoliformis accumulated similar levels of Na+ in their shoots, Suaeda calceoliformis plants from the two higher densities in the low-salinity treatment accumulated twice as much total Na+ per pot than A. prostrata, and seven times more Na+ than Salicornia europaea. Based on these laboratory studies, Suaeda calceoliformis planted in densities ranging from 15 to 30 plants∙100 cm−2 would accumulate more Na+ from saline-contaminated soils than the other species. Key words: bioremediation, Atriplex, Hordeum, Salicornia, Spergularia, Suaeda..