Effects of different rootstocks on the growth and cadmium-accumulation characteristics of a post-grafting generation of Cyphomandra betacea seedlings

To study the cadmium (Cd)-accumulation characteristics of the post-grafting generation of Cyphomandra betacea (Cav.) Sendt., the seeds of C. betacea grafted on Solanum nigrum L., tomato, and eggplant rootstocks were collected and planted in Cd-contaminated soil. Compared with seeds of ungrafted seedlings, the S. nigrum rootstock increased the shoot biomass of the post-grafting generation of C. betacea seedlings, while eggplant and tomato rootstocks decreased or had no significant effects. Only the S. nigrum rootstock increased the chlorophyll a content, net photosynthetic rate, and stomatal conductance of the post-grafting generation of C. betacea seedlings, while the other rootstocks decreased or had no significant effects on these photosynthetic parameters. The S. nigrum rootstock enhanced the superoxide dismutase and catalase activities, and soluble protein content, of the post-grafting generation of C. betacea seedlings, while the other rootstocks reduced or had no significant effects on these parameters. The three rootstocks decreased the Cd contents in different organs of the post-grafting generation of C. betacea seedlings, and the order of treatments was ungrafted > tomato rootstock > eggplant rootstock > S. nigrum rootstock. Therefore, S. nigrum was the best rootstock to promote the growth and decrease the Cd contents in post-grafting generation of C. betacea, and this can benefit C. betacea production in Cd-contaminated areas.