喷施锌肥对油菜镉锌生物可给性的影响

Effect of Foliar Zinc Application on Bioaccessibility of Cadmium and Zinc in Pakchoi

采用溶液培养和体外消化实验,研究不同Zn营养条件下,喷施ZnSO_4和ZnNa_2EDTA对两种油菜Cd、Zn质量分数以及生物可给性的影响,计算人体通过食用油菜摄入Cd、Zn的量,评估喷施Zn肥降低人体Cd摄入提高Zn吸收的潜力.结果表明,正常Zn营养下油菜地上部Cd质量分数显著低于缺Zn条件下,喷施ZnNa_2EDTA显著降低油菜Cd质量分数;正常Zn营养下油菜地上部Zn质量分数显著高于缺Zn条件下,喷施Zn肥可显著提高油菜Zn质量分数,其中喷施ZnSO_4处理效果最佳.正常Zn营养下油菜Cd的生物可给性显著低于缺Zn条件下,喷施Zn肥显著降低油菜Cd在胃阶段的生物可给性,与对照相比最大降幅为35.81%,喷施ZnSO_4显著降低Cd在小肠阶段的可给性,最大降幅为59.24%;喷施Zn肥使油菜Zn在胃和小肠阶段的生物可给性显著低于对照处理,最大降幅为68.90%,其中ZnSO_4降低效果明显强于ZnNa_2EDTA.食用Cd污染的普通油菜寒绿摄入Cd的量超过世界卫生组织推荐的每日耐受值,通过选择低积累油菜华骏或喷施ZnSO_4可以显著减少人体摄入Cd的量,有效降低Cd过量摄入的健康风险;食用未喷施Zn肥或喷施低浓度ZnNa_2EDTA的油菜有Zn摄入不足的风险,而食用喷施ZnSO_4或高浓度ZnNa_2EDTA的油菜可以满足蔬菜膳食Zn摄入的需要,其中喷施ZnSO_4效果更好.总之,喷施Zn肥可显著降低油菜地上部Cd、Zn的生物可给性,有效减少人体食用油菜摄入Cd的量,提高摄入Zn的量,其中喷施ZnSO_4处理的效果最佳.

Two cultivars of pakchoi with different cadmium（Cd） accumulation were grown in nutrient solutions containing low and sufficient zinc（Zn） levels.ZnSO4 and ZnNa2EDTA were applied as foliar fertilizers.The bioaccessibilities of Cd and Zn in pakchoi were assessed by the in vitro digestion method,and the bioaccessible established daily intakes（BEDI） of Cd and Zn from pakchoi were calculated.The effect of foliar zinc application on concentrations,bioaccessibilities,and BEDIs of Cd and Zn in pakchoi was evaluated.Results show that the Cd concentrations in shoots of the tested pakchoi cultivars under sufficient Zn condition were significantly lower than those under low Zn condition,and foliar application of ZnNa2EDTA significantly decreased the Cd concentrations of pakchoi.The tested pakchoi cultivars with sufficient Zn had a significantly higher mean shoot Zn concentration than those with low Zn.Foliar Zn treatments significantly increased shoot Zn concentrations of pakchoi,with the highest in the ZnSO4 treatment.Cd bioaccessibility in the tested pakchoi cultivars with sufficient Zn was significantly lower than that with low Zn.Foliar applied Zn could significantly reduce Cd bioaccessibility in the gastric phase,with a maximal reduction of 35.81% compared to the control.Foliar treatment with ZnSO4 could significantly decrease Cd bioaccessibility in the small intestinal phase,with a maximal reduction of 59.24% compared to the control.Foliar Zn treatments reduced significantly the Zn bioaccessibility of pakchoi in the gastric and small intestinal phases,with a maximal reduction of 68.90% compared to the control.The reduction of Zn bioaccessibility was higher in the ZnSO4 treatment than in the ZnNa2EDTA treatment.Via the consumption of the Cd-contaminated common cultivar Hanlv,the BEDI values of Cd were higher than that of the provisional tolerable daily intake（PTDI） standard of WHO [0.83μg·（kg·d）-1].However,via the consumption of the low-Cd accumulating cultivar Huajun or pakchoi with foliar application of ZnSO4,the BEDI values of Cd decreased significantly and were below the PTDI value.Via the consumption of pakchoi in the control orlow-level ZnNa2EDTA treatments,the BEDI values of Zn were below that of the recommended nutrient intake for Zn.However,via the consumption of pakchoi with foliar application of ZnSO4 or high-level ZnNa2EDTA,the BEDI values of Zn were higher than that of the recommended nutrient intake and met the human needs for Zn from vegetables.Under the ZnSO4 treatment,the BEDI values of Zn from pakchoi were the highest.In conclusion,foliar zinc application could significantly reduce the bioaccessibilities of Cd and Zn in pakchoi and the BEDI values of Cd and increase the BEDI values of Zn.Foliar application with ZnSO4 was the most suitable treatment to reduce Cd intake and increase Zn intake from pakchoi.