Cd uptake and accumulation of Brassica napus varieties with different seed glucosinolate characteristics

Cd uptake and translocation of rape (Brassica napus) are affected not only by exogenous S supply, but also closely related with its S metabolism. Glucosinolate is an important S-containing secondary metabolite, and its content of rape seed can well characterize the glucosinolate characteristics of rape. The relationship between seed glucosinolate characteristics and Cd uptake and accumulation by rape was investigated through a field experiment in Cd contaminated soils to explore Cd uptake of rape varieties with different glucosinolate characteristics of seed. The results showed that the orders of Cd contents in different organs of the two types of rapes (high-glucosinolate and low-glucosinolate) were the same, root > leaf > stem at early blooming stage and stem > root > shell > seed at mature stage. There were no significant differences between high-glucosinolate rapes and low-glucosinolate rapes in uptake and accumulation of Cd at early blooming stage, while the Cd uptake and accumulation of high-glucosinolate rapes were lower than thoes of low-glucosinolate rapes at mature stage. The Cd contents of root, stem, shell, seed were 3.90 mgkg^-1, 4.50 mgkg^-1, 0.97 mgkg^-1, 0.17 mgkg^-1 in the high-glucosinolate rape. They were 4.57 mgkg^-1, 5.20 mgkg^-1, 1.32 mgkg^-1, 0.29 mgkg1 in the low-glucosinolate rape, which were 17.18% (P < 0.05), 15.56% (P < 0.05), 36.08% (P < 0.05) and 70.59% (P < 0.05) higher than the former, respectively. The high-glucosinolate rapes could restrain Cd transfer from stem to the superior organs (shell and seed). The translation coefficients of Cd from stem to shell (shell/stem) and from shell to seed (seed/shell) were significantly different between two types of rape, which were 0.22 and 0.17 in the high-glucosinolate rapes, 0.25 and 0.23 in the low-glucosinolate rapes at mature stage, respectively. The purifying rate of soil Cd was 0.90% for the low-glucosinolate rapes and 0.76% for the high-glucosinolate rapes. As the enrichment plant in Cd contaminated soils, the purification ability of rapes need to be improved.