摘要：

Sulfate complexation of Cd in nutrient solution has been shown to have little impact on Cd uptake by plants. This study examined the effect of sulfate added to soil on Cd concentrations in soil solution and Cd uptake by Swiss chard (Beta vulgaris L. cv. Fordhook Giant). Swiss chard was grown in soil which was wetted with complete nutrient solution containing equivalent salt concentrations of NaNO or NaSO. Plant growth was reduced by increasing both NO and SO concentrations in soil solution, with growth reductions similar for both salts. The Cd concentration in soil solution increased (P < 0.05) more consistently with increasing concentrations of SO compared to NO in soil solution. Solution speciation, calculated with GEOCHEM-PC, showed significant increases of Cd activities with increasing salt rates. Shoot Cd content in 19-day-old Swiss chard plants was marginally but significantly (P < 0.05) increased with increasing SO concentration but no effect was observed with increasing NO concentration. These results are compared with earlier work on the marked effect of Cl salinity on Cd availability in Swiss chard. Possible mechanisms explaining the smaller effect of SO compared to Cl on Cd availability are proposed.

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