Effects of the metal pollutants cadmium and nickel on soybean seed development

The chloride salts of Cd or Ni were added to the nutrient solution in which soybean (Glycine max) plants were grown and the response of the plants to these pollutants examined. Both metals markedly reduced plant biomass and s eed production. Accumulation was mostly in the roots. Nickel was more mobil e than Cd, reaching higher levels in all plant parts, especially seeds. Wit hin the tissues of mature seeds, the highest concentrations of Ni were foun d in the axis and testa. The highest concentrations of Cd were in the testa and cotyledon, and the lowest in the axis. When expressed on a per seed ba sis, metal contents of these organs increased with developmental age. Nicke l amounts were lower in the pods than the seeds for all growth stages, howe ver there was no significant difference for Cd. Cadmium reduced mature seed mass. This effect was mostly due to decreased yields of lipids, protein an d carbohydrates. Although the number of seeds per pod declined as a respons e to Ni, seed mass was unaffected and there was no apparent effect on stora ge reserves.