Molasses melanoidin-like products enhance phytoextraction of lead through three Brassica species

ABSTRACT

Previously, it has been suggested that melanoidin-like products (MLP) from sugarcane molasses may accelerate copper phytoextraction. In this study, we evaluated the facilitatory effect of MLP on phytoextraction in a medium including cadmium or lead, the concentrations of which were adjusted around the regulation values of the Soil Contamination Countermeasures Act in Japan. Three Brassica species were tested based on their fast growth, high biomass productivity, and high heavy metal absorption. Both biomass and lead uptake in the nutrient medium with 1 mM lead nitrate were significantly increased by the addition of MLP, and almost all of the lead was accumulated in the root tissue. Therefore, MLP were able both to detoxify lead ions and to improve their bioavailability in Brassica species. In contrast, only these species with MLP or citric acid survived in the nutrient medium with 1 mM cadmium sulfate. The phytoextraction of cadmium using these species was therefore impractical under the Act.

KEYWORDS:

• Brassica species
• melanoidin
• sugarcane molasses

Acknowledgments

The authors are grateful to Mr. Akira Shibuya (Kaneko Seeds Co., Ltd., Japan) for giving the seeds of horticultural mustard and rapeseed.

Funding

Financial supports for this research in Japan were provided partly by the “Element Innovation” project in MEXT and by JSPS KAKENHI under Grant number 26340069.