Intensification of Solanum nigrum L. remedying cadmium contaminated soils by nitrogen and potassium fertilizers

Outdoor pot-culture experiments were carried out to study the effects of nitrogen fertilizer [(NH4)2SO4] and potassium fertilizer (KCl) on plant growth and cadmium (Cd) accumulation in Solanum nigrum L., a Cd-hyperaccumulator. Although (NH4)2SO4 could not significantly increase Cd concentration in aboveground tissues of S. nigrum, it could markedly enhance dry biomass of aboveground parts, thus it significantly increased Cd accumulation in the shoots with a maximal increase of 2.8 folds. In contrast, KCl could significantly increase Cd concentration in aboveground tissues of S. nigrum at its highest addition level, but it might inhibit dry biomass of aboveground parts, so it could not enhance Cd accumulation in the shoots of S. nigrum. And the application of (NH4)2SO4 could significantly reduce pH values in soils, but the concentration of available Cd in soils was not affected markedly. However, the application of KCl could significantly increase pH values in soils, and could markedly enhance the concentration of available Cd in soils. These results indicated that enhancing phytoremediation effect of (NH4)2SO4 was better than that of KCl, and (NH4)2SO4 could be applied to strengthen S. nigrum phytoremediation of Cd-contaminated soils.