College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, Guangdong, PR China; Key Laboratory of Tropical Agricultural Environment in South China, Ministry of Agriculture and Rural Affairs, Guangzhou, 510642, Guangdong, PR China; Guangdong Provincial Key Laboratory of Eco-Circular Agriculture, Guangzhou, 510642, Guangdong, PR China.
College of Agriculture, South China Agricultural University, Guangzhou, 510642, Guangdong, PR China.
J Environ Manage. 2022 Jan 15;302(Pt A):114039. doi: 10.1016/j.jenvman.2021.114039. Epub 2021 Nov 5.
Silicon (Si) has the potential to ameliorate the toxic effects of cadmium (Cd) on rice growth and mitigate Cd-uptake by rice under Cd-contaminated soil. However, it is not completely clear whether there are differences in the impacts of different Si management on the chemical behavior of Cd in soil-rice system under Cd-contaminated paddy field. Here, pot trials were conducted to explore the effects of three modes of Si application (T-applying Si at transplanting stage, J-applying Si at jointing stage, TJ-applying Si at transplanting stage and jointing stage with a ratio of 50% to 50%) on the accumulation of Cd in rice grain and the toxic risk of Cd on human health in rice consumption under Cd-polluted soil (4.21 mg·kg), and that without Si application was used as control (CK). Results showed that rice growth and Cd-retention in root were enhanced by Si application, and the retention of Cd in TJ root was the highest, reaching 82.36%∼84.06% of total Cd absorbed by rice plant. TJ also elevated soil pH and CEC value significantly during the whole growth period, diminished Cd availability and converted exchangeable-Cd into residual-Cd in soil. Moreover, Si application reduced Cd concentration in iron plaque, while TJ had the lowest concentration of DCB-Cd and the highest molar ratios of Fe/Cd and Mn/Cd. The bioaccessibility of Cd from grains and cooked rice were decreased by Si application. Compared with T and J, the hazard quotient of digestion from cooked white rice of TJ in gastric phase was reduced by 19.61% and 21.94%, respectively. In brief, TJ had more efficiency on reducing the Cd availability in soil during the rice growing period, promoting the retention of Cd in root, decreasing Cd uptake by rice plant and distribution to grains, as well as the bioaccessibility of Cd from cooked rice. These results also provide a novel strategy of Si application to decrease the risk of Cd migration in the soil-rice-humans system and simultaneously promote rice yields.
硅（Si）有可能减轻镉（Cd）对水稻生长的毒害作用，并减少 Cd 污染土壤中水稻对 Cd 的吸收。然而，在 Cd 污染稻田土壤条件下，不同 Si 管理方式对土壤-水稻系统中 Cd 化学行为的影响是否存在差异尚不完全清楚。本研究采用盆栽试验，探讨了 T（移栽期施硅）、J（拔节期施硅）和 TJ（移栽期和拔节期各施 50%硅）3 种硅肥施用方式对 Cd 污染土壤（4.21 mg·kg）中水稻籽粒 Cd 积累和人体健康 Cd 毒害风险的影响，以不施硅肥为对照（CK）。结果表明，施硅可促进水稻生长和根内 Cd 滞留，TJ 根内 Cd 滞留量最高，达植株吸收 Cd 总量的 82.36%∼84.06%。TJ 还可显著提高整个生育期土壤 pH 和 CEC 值，降低土壤 Cd 有效性，将可交换态 Cd 转化为残留态 Cd。此外，施硅降低了铁膜中 Cd 的浓度，而 TJ 处理的 DCB-Cd 浓度最低，Fe/Cd 和 Mn/Cd 摩尔比最高。施硅降低了稻谷和米饭中 Cd 的生物可给性。与 T 和 J 相比，TJ 处理的 TJ 米饭在胃阶段的消化危害系数分别降低了 19.61%和 21.94%。总之，TJ 处理在水稻生长期间更有效地降低了土壤中 Cd 的有效性，促进了 Cd 在根内的滞留，减少了水稻植株对 Cd 的吸收和向籽粒的分配，以及降低了米饭中 Cd 的生物可给性。这些结果还为利用 Si 降低土壤-水稻-人类系统中 Cd 迁移风险、同时促进水稻产量提供了一种新策略。
