Identification of a new potential Cd-hyperaccumulator Solanum photeinocarpum by soil seed bank-metal concentration gradient method

Abstract

A new method, soil seed bank-metal concentration gradient method was used to screen for heavy metal hyperaccumulators, and Solanum photeinocarpum was found to be a potential Cd-hyperaccumulator. The chlorophyll content and photosynthetic rate of S. photeinocarpum were not affected by Cd pollution, while leaf stomas and transpiration rate were significantly decreased by more than 60 mg kg −1 Cd, and leaf water use efficiency and shoot water content were significantly increased by more than 60 or 100 mg kg −1 Cd, respectively. In the seed bank-Cd concentration gradient experiment, the shoot biomass of S. photeinocarpum showed no significant reduction with soil Cd treatment as high as 100 mg kg −1, but the root biomass was significantly reduced by more than 60 mg kg −1 Cd contamination. Plant tissues accumulated 544, 132 and 158 mg kg −1 Cd in roots, stems and leaves, respectively, and extracted 157 and 195 μg Cd plant −1 in roots and shoots at 100 mg kg −1 Cd in soil, respectively. In the transplanting-Cd concentration gradient experiment, plant shoot biomass and root biomass were unaffected by soil Cd as high as 60 mg kg −1. Plant tissues accumulated 473, 215 and 251 mg kg −1 Cd in roots, stems and leaves, respectively, and extracted 176 and 787 μg Cd plant −1 in roots and shoots at 60 mg kg −1 soil Cd, respectively. Soil seed bank-metal concentration gradient method could be an effective method for the screening of hyperaccumulators.