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A microcosm experiment with artificially contaminated soils was conducted in a greenhouse to evaluate the effect of gibberellic acid 3 (GA3) on phytoremediation efficiency of Solanum nigrum L. The GA3 was applied at three different concentrations (10, 100, 1000 mg L(-1)) to S. nigrum. Results indicated that GA3 can significantly (p < 0.05) increase the biomass of S. nigrum by 56 % at 1000 mg L(-1). Concurrently, GA3 application increased Cd concentrations in the shoot of S. nigrum by 16 %. The combined effects resulted in an increase in the amount of Cd extracted by a single plant by up to 124 %. Therefore, it is possible to use GA3 to promote the Cd phytoremediation efficiency of S. nigrum.

In this study, Beta vulgaris L. var. cicla was grown in cadmium-contaminated soil in a greenhouse. Regulated deficit irrigation was applied using three different irrigation levels (T1: 300 L, T2: 200 L, T3: 100 L per block during each irrigation event during the organogenesis stage; T1 was the control) to examine the effects on phytoremediation efficiency. According to the experimental results, the regulated deficit irrigation treatment (T2) decreased the Beta vulgaris L. var. cicla shoot biomass by 15.8%, increased the Cd concentration in the shoots by 23%, and maintained a constant root-shoot ratio. By contrast, T3 decreased the Beta vulgaris L. var. cicla shoot biomass by 33.0%, decreased the Cd concentration in shoots by 9.8%, and increased the root-shoot ratio by 62.8%. The Cd remediation potential efficiency (PE) of treatment T2 was 5.42 g ha-1-i.e., 39.7% higher than that of T1 and 61.8% higher than that of T3. This study indicated that regulated deficit irrigation can be used to enhance Cd phytoremediation and save water, but should be applied in a suitable way.

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A two-year in-situ phytoremediation trial was launched in Shenyang Zhangshi (Sewage) Irrigation Area (SZIA). The phytoremediation efficiency of Solanum nigrum L. was determined, by both monitoring the change of soil Cadmium level in the upper 20 cm of soil, and calculating the plant uptake of soil Cd. After two years experimental, by monitoring the soil Cd concentrations, The Cd concentrations decreased on average from 2.75 mg kg(-1)to 2.45 mg kg(-1) in the first year and from 2.33 mg kg(-1) to 1.53 mg kg(-1) in the second year, amounting to a decrease by a factor of 10.6% in the first year and 12% in the second year. After two years phytoremediation by S. nigrum, Cd concentrations of the seven experimental plots with S. nigrum growth decreased from 2.75 mg kg(-1) to 1.53 mg kg(-1), a decrease by a factor of 24.9%. And the soil Cd concentration decreased only 2.1% and 1.7% in the bared experimental plot. And the calculating of Cd uptake by S. nigrum shown that, the plants uptake 4.46% and 5.18% of the total soil Cd in 2008 and 2009, while the soil Cd concentrations decreased by a factor of 10.6% in 2008 and 12.1% in 2009.