Lesquerella growth and selenium uptake affected by saline irrigation water composition

A greenhouse study was conducted to determine the effects of waters differing in salt composition on growth and selenium (Se) accumulation by lesquerella (Lesquerella fendleri Gray S. Wats.). Plants were established by direct seeding into sand cultures and irrigated with solutions containing either (a) Cl- as the dominant anion or (b) a mixture of salts of SO42- and Cl-. Four treatments of each salinity type were imposed. Electrical conductivities of the irrigation waters were 1.7, 4, 8, and 13 dS m(-1). Two months after salinization, Se (1 mg l(-1), 12.7 muM) was added to all solutions as Na2SeO4. Shoot growth was significantly reduced by increasing Cl-salinity. Regardless of salinity type, concentrations of Ca2+, Mg2+, Cl-, total-S, and Se were higher in the leaves than the stems, whereas K+ and Na+ were higher in the stem. Leaf-Se concentrations were not significantly affected by Cl-based irrigation waters, averaging 503 mg Se kg(-1) dry wt across salinity levels, whereas leaf-Se decreased consistently and significantly from 218 to 13 mg kg(-1) as mixed salt salinity increased. The dramatic reduction in Se was attributed to SO42-:SeO42- competition during plant uptake. The strong Se-accumulating ability of lesquerella suggests that the crop should be further evaluated as a potentially valuable phytoremediator of Se-contaminated soils and waters of low to moderate salinity in areas where the dominant anion in the substrate is Cl-. Published by Elsevier Science B.V.