Cadmium subcellular distribution and chemical form in Festuca arundinacea in different intercropping systems during phytoremediation.

Intercropping with Cicer arietinum L has been suggested to improve the Cd decontamination capacity of Festuca arundinacea. However, the mechanisms stimulating this effect have not been revealed. The current study was designed to evaluate the changes in the subcellular distribution and chemical forms of Cd in different leaf types of F. arundinacea intercropped with C. arietinum L under different schemes. The results indicated that more than half of the Cd was bound in the cell wall in plant organs under all planting schemes, showing that cell wall deposition is an important detoxication pathway for the metal. Relative to the monoculture scheme, coordinate and malposed intercropping schemes increased the Cd concentration deposited in the cytoplasm of below-ground tissues from 37.6% to 45.2% and 45.1%, respectively. Additionally, the proportion of inorganic and water-soluble Cd in the below-ground parts of F. arundinacea increased from 73.6% in the monoculture scheme to 80.6% and 84.7%, in the coordinate and malposed intercropping schemes, respectively. The results exhibited that intercropping schemes can activate the metal in below-ground tissues and move it to aerial parts. The present study revealed the promoting mechanism of intercropping schemes on the phytoremediation efficiency of F. arundinacea for Cd at a subcellular level.