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Growth and trace element concentrations of five plant species grown in a highly saline soil

Retana, J., Parker, D.R., Amrhein, C., Page, A.L.
Journal of environmental quality 1993 v.22 no.4 pp. 805-811
grasses, Achnatherum hymenoides, salt tolerance, boron, metal tolerance, heavy metals, electrical conductivity, soil depth, shoots, yields, bioremediation, genotype, Astragalus racemosus, California
Kesterson Reservoir and other impoundments in the San Joaquin Valley, California, have received large volumes of saline irrigation drainage water that is enriched with trace elements, including As, B, Mo, Se, U, and V. When these ponds are allowed to dry and revert to terrestrial ecosystems, careful soil water and vegetation management may be needed to prevent toxicological hazards to wildlife and/or livestock. We conducted a 248-d column study in the greenhouse using a soil from Kesterson to assess the growth of salt- and B-tolerant genotypes, and to determine the uptake of As, B, Mo, Se, U, and V by these genotypes. Electrical conductivity decreased with soil depth, from 14 to 5 dS m-1, with B, Mo, Se, and U concentrations paralleling the soil salinity, whereas As and V were higher in the subsoil. Three grasses, alkali sacaton [Sporobolus airoides (Torr.) Torr.], tall wheatgrass [Elytrigia pontica (Podp.) Holub], Indian ricegrass [Oryzopsis hymenoides (Roem & Schult.)], and two Se-accumulators, Astragalus bisulcatus (Hook.) and A. racemosus Pursh., were successfully established after a preplanting leaching treatment to reduce salts in the seed zone. Three cuttings of alkali sacaton and tall wheatgrass resulted in total shoot yields of 11.1 and 7.6 g per column, respectively, but only 0.8 for a single cutting to the less salt- and B-tolerant Indian ricegrass. The slower-growing A. bisulcatus and A. racemosus yielded 3.8 and 4.4 g per column, respectively. Shoot concentrations of As, U, and V were low (< 3 mg kg-1) in all genotypes, and do not seem to pose food-chain transfer hazards at this site. Molybdenum and Se shoot concentrations of all genotypes exceeded the upper safe limits for consumption by ruminants, and shoot B concentrations were also high (> 60 mg kg-1). Despite high soil solution SO4 concentrations, both Astragalus species accumulated Se to high concentrations in the shoots (ca. 650 mg kg-1), and shoot harvest removed the equivalent of 2 to 3.5 kg Se ha-1. Growth of these Se-accumulating species shows promise as a means of direct removal of Se from Se-contaminated sites and could become a component of effective remediation strategies.