Effects of mutual grafting on cadmium accumulation characteristics of first post-generations of Bidens pilosa L. and Galinsoga parviflora Cav.

We studied the effects of mutual grafting on cadmium (Cd) accumulation characteristics on the first post-generations of the Cd-hyperaccumulator plants Bidens pilosa L. and Galinsoga parviflora Cav. The seeds from scions and rootstocks of B. pilosa and G. parviflora were collected and planted in Cd-contaminated soil in pot and field experiments. In the pot experiment, rootstock treatment increased the shoot biomass of B. pilosa post-grafting generations, compared with ungrafted B. pilosa, but decreased the Cd content in shoots and Cd extraction by shoots of post-grafting generations; scion treatment decreased or had no significant effect. Mutual grafting resulted in no significant differences to the photosynthetic pigment contents in B. pilosa post-grafting generations. Compared with ungrafted G. parviflora, scion treatment increased the shoot biomass, photosynthetic pigment content, and Cd extraction by shoots of G. parviflora post-grafting generations, but rootstock treatment did not lead to significant differences. Mutual grafting resulted in no significant differences to the Cd contents in shoots of G. parviflora post-grafting generations. In the field experiment, only rootstock treatment increased the shoot biomass of B. pilosa post-grafting generations, and only scion treatment increased the shoot biomass and the Cd extraction by shoots of G. parviflora post-grafting generations. Therefore, mutual grafting of scions may enhance the phytoremediation ability of G. parviflora first post-grafting generations.