Abstract: A field trial was conducted in heavy metal-contaminated agricultural land located in Gejiu City, Yunnan Province to investigate characteristics of Pb, Cd and As absorption and Pb, Cd and As contaminated farmland remediation potentials of Solanum nigrum, Pteris cretica var. nervosa and Tephrosia candida as affected by planting mode of the plants. The mean concentrations of Cd and As in the experiment soil were both beyond the criteria of Grade III in the “Environment Quality Standard for Soils”(GB 15618-1995). Regardless of planting mode, Cd uptake or concentration was the highest in the shoots of S.nigrum, reaching (6.99±0.25 )mg•kg^-1, As uptake the highest in the shoots of P. cretica var. nervosa, reaching (326.98±93.99) mg•kg^-1, and Pb uptake the highest in the shoots of T. candida, reaching (32.96±5.65) mg•kg^-1. However, these values are still lower than the threshold concentrations for hyperaccumulators i.e. 100 mg•kg^-1 for Cd, 1000 mg•kg^-1 for As and 1000 mg•kg^-1 for Pb. Comparison of planting modes show that in the mode of S. nigrum being planted alone, Pb, Cd and As uptake was all the highest in the shoots of the plant, reaching 1004.97 , 152.04 and 1534.47 g•hm^-2•a^-1, respectively. If the Cd and As contaminated farmland is to be remedied up to the criteria of Grade III in the “Environment Quality Standard for Soils”(GB 15618-1995), the phytoextraction rate of Cd and As should be 2.8116% and 1.413%, respectively, which indicates that the planting mode of monocropping of S.nigrum is a potential method to remedy Pb, Cd and As contaminated farmland, but not fit for remediation of farmlands highly contaminated with heavy metals.

Key words: heavy metals, phytoremediation, Solanum nigrum, Pteris cretica var. nervosa, Tephrosia candida, farmland