Does sulfur application continue to reduce cadmium accumulation and increase the seed yield of oilseed rape (Brassica napus L.) at the maturity stage?

BACKGROUND Oilseed rape requires sulfur (S) fertilization. Cadmium (Cd) differs dramatically in agricultural soils. Rice-oilseed rape rotation distributes widely and contributes the majority of rapeseeds in Asian countries. It was reported that S metabolism was involved in Cd uptake in seedlings of oilseed rape, although the effects of S on Cd accumulation and seed yield at maturity are still unclear. RESULTS We performed a pot experiment including two Cd rates (0.35 and 10.35 mg kg(-1), as low and high Cd soil) and four S levels (0, 30, 60 and 120 mg kg(-1)). The results showed that low S application (30 mg kg(-1)) resulted in two-fold higher seed-Cd concentration irrespective of soil Cd levels. The responsible mechanism might be that Cd translocation into rapeseeds was involved in sulfate transporters, which could be strongly expressed in shoots and roots when supplying sulfate under S-starvation conditions, but depressed under a S-sufficient environment. For high Cd soil, seed yield decreased by 36%, 48% and 72% at 30, 60 and 120 mg S kg(-1) compared to non-S treatment, whereas there were no differences for low Cd soil. Antagonistic effects of S and Cd existed for seed yield according to structure equation model analysis. CONCLUSION Oilseed rape can be grown in low-Cd fields as a safe food crop with high levels of sulfur fertilizers (>60 mg S kg(-1)). In high-Cd fields, oilseed rape is recommended as a Cd-remediation crop, and rapeseeds should only be used for industrial purposes and not for food. (c) 2021 Society of Chemical Industry.