Silicon-mediated alleviation of Cadmium toxicity on Thujopsis dolabrata

We conducted pot experiments on the cypress Thujopsis dolabrata (Linn. f.) Sieb. et Zucc. in order to study the interaction of silicon (Si) and root exudates on cadmium (Cd) bioavailability in the rhizosphere,. Each variety was planted with 100 mg/kg Cd and/or 400 mg/kg Si for 210 days. The results showed that adding Si increased Cd tolerance in T. dolabrata, but that the mechanism was specifical. In T. dolabrata, Si did not prevent Cd translocation from roots to shoots, and it significantly enhanced Cd accumulation without inhibiting growth. Moreover, Si mobilized Cd from the rhizospheric soil by stimulating phenolic exudation from the roots, suggesting that Cd-chelation combined with Si-induced phenolics were involved in Cd detoxification.