Selenium Assimilation and Differential Response to Elevated Sulfate and Chloride Salt Concentrations in Two Saltgrass Ecotypes

A comparative study of selenium (Se) assimilation under the influence of sulfate and chloride salt salinity was conducted on two saltgrass ecotypes. The inland saltgrass grows successfully on the soil contaminated with elevated Se concentrations at Kesterson, Merced County, California. The coastal saltgrass colonizes a tidal salt marsh in Bodega Bay on the coast of California. The saltgrass samples were grown in sand culture and irrigated with quarter concentration of modified Hoagland solution supplemented with different concentrations of Se with or without sulfate or chloride salt. The Bodega Bay plants exhibited greater tolerance to both the sulfate and chloride salinity than the Kesterson plants. The plants of both ecotypes accumulated about 90% of their total tissue Se in the nonprotein fraction. When sulfate was present in the irrigation solution, the Kesterson plants assimilated significantly less Se in its protein and nonprotein fractions than in the Bodega Bay plants. Under Se treatment, chlorosis symptoms were found on the leaves of the Bodega Bay plants, but not on the leaves of the Kesterson plants. The above results demonstrate that the two saltgrasses are distinct ecotypes in respect to their salinity tolerance and the ability of mitigation of selenium assimilation in the presence of sulfate.