Abstract:
Objective Uptakes of Cd and Zn by sweet potato plants from Cd polluted soil was investigated.
Method A pot experiment was conducted on the sweet potato to study the effects of Cd-stress on the yield, nutritional quality as well as the Cd and Zn uptakes of the plants. Migration and transformation of Cd and Zn from soil to plants were analyzed.
Result The tuber yield of the plants decreased with increasing Cd in soil. It maximized at a reduction of 32.6%. The food quality of the tubers was greatly affected by the stress with a reduction on proteins as high as 32.1%. Cd-stress significantly increased the Cd concentrations in various parts of a plant land the soil, and inhibited the Zn absorption by the tubers. Sweet potato plants are not highly capable in absorbing Cd and can only reduce Cd in soil to a limited extent. Thus, so long as Cd in soil was less than 5 mg·kg-1, the tubers grown on it were basically safe for consumption as the Cd content in tuber would likely be below the national standard for safety (Cd ≤ 0.1 mg·kg-1). The Cd accumulations in parts of a plant were found to rank in the order of roots > stems > peel > leaves > flesh.The migration and transformation abilities of root and stem for Cd were higher, making Cd mainly accumulated in root.
Conclusion Planting sweet potatoes could help mitigate the pollution effect only in soils not heavily contaminated with Cd. By eliminating the more Cd-concentrated roots on a tuber for food, risks on health could be largely avoided.
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