Cadmium accumulation in different pakchoi cultivars and screening for pollution-safe cultivars.

The selection and breeding of pollution-safe cultivars (PSCs) is a practicable and cost-effective approach to minimize the influx of heavy metal to the human food chain. In this study, both pot-culture and field experiments were conducted to identify and screen out cadmium pollution-safe cultivars (Cd-PSCs) from 50 pakchoi (Brassica rapa L. ssp. chinensis) cultivars for food safety. When treated with 1.0 or 2.5 mg/kg Cd, most of the pakchoi cultivars (>70%) showed greater or similar shoot biomass when compared with the control. This result indicates that pakchoi has a considerable tolerance to soil Cd stress. Cd concentrations in the shoot varied significantly (P<0.05) between cultivars: in two Cd treatments (1.0 and 2.5 mg/kg), the average values were 0.074 and 0.175 mg/kg fresh weight (FW), respectively. Cd concentrations in the shoots of 14 pakchoi cultivars were lower than 0.05 mg/kg FW. In pot-culture experiments, both enrichment factors (EFs) and translocation factors (TFs) of six pakchoi cultivars were lower than 1.0. The field studies further confirmed that the Hangzhouyoudonger, Aijiaoheiye 333, and Zaoshenghuajing cultivars are Cd-PSCs, and are therefore suitable for growth in low Cd-contaminated soils (≤1.2 mg/kg) without any risk to food safety.

[Differences in cadmium absorption and accumulation of Brassica varieties on cadmium-polluted soil].

A pot experiment was conducted to study the differences in cadmium (Cd) absorption and accumulation of sixty Brassica varieties on the soils added with different concentration of Cd. The results showed that when the soil Cd concentration was 0.6 mg x kg(-1) and 1.2 mg x kg(-1), the percentage of test Brassica varieties whose Cd content exceeded the National Edible Standard was 8.33% and 66.67%, respectively, suggesting that Brassica was easy to be Cd-polluted. The shoot Cd content of all test varieties was below the National Edible Standard, and the biomass of the varieties Changgengbaicai, Shanghaiqing, Aijisuzhouqing, Qingyou 4, Aijiaokuipianheiyebaicai, Zhouyeheiyoudonger, Gaohuaqinggengbaicai, Zaoshenghuajing, Jinguanqingjiangbai, Xiawangqinggengcai, Lifengqinggengbaicai, and Hangzhouyoudonger was not affected. These 12 Brassica varieties could be planted on the soils with light Cd pollution.