Bao Qiongli, Bao Wankui, Ding Yongzhen, Huang Yizong
Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin, 300191, China.
Institute of Agricultural Resource and Regional Planning, China Academy of Agricultural Sciences, Beijing, 100081, China.
Environ Sci Pollut Res Int. 2022 Jan;29(2):2853-2865. doi: 10.1007/s11356-021-15570-2. Epub 2021 Aug 11.
Water management has opposite effects on the bioavailability of Cd and As in soil. In order to identify the most efficient water management strategy for reducing Cd and As accumulations and amino acid (AA) synthesis in rice in two soils with different Cd and As contents, a pot experiments were conducted in greenhouse. A treatment consisting of 5 days of flooding followed by 3 days of drainage (F5D3, repeated every 8 days) was identified as the most effective treatment for simultaneously decreasing Cd and As in grains, with reductions of grain Cd and As contents of more than 80.0% and 73.1%, respectively, compared with either a drained treatment or a flooded treatment alone; this is probably related to the high efficiency of the F5D3 treatment in reducing dissolved Cd and As according to its minimum "trade-off value" (an index for evaluating the degree of trade-off between soil solution As and Cd concentrations in water management condition), due to the variations in grain Cd and As contents which were significantly correlated with the variations in soil solution Cd (R=0.98) and As (R=0.92, P=0.0001) concentrations. Additionally, grain Cd content was also significantly related to the organs Cd contents (especially root Cd content, R=0.99) and the root-to-shoot Cd translocation factors (R=0.99), whereas grain As content was significantly related to soil Eh (R=-0.82, P=0.003) and pH (R=0.88, P=0.0008). The AA contents in organs under the F5D3 treatment were lower than those under the flooded and drained treatments. These results indicated that the F5D3 treatment was the most effective water management strategy for simultaneously reducing grain Cd and As contents and AA synthesis in rice, which was probably due to there being no need for rice to synthesize abundant AAs to chelate metal ions.
水分管理对土壤中镉和砷的生物有效性具有相反的影响。为了确定在两种镉和砷含量不同的土壤中，减少水稻中镉和砷积累以及氨基酸（AA）合成的最有效水分管理策略，在温室中进行了盆栽试验。一种由5天淹水后接着3天排水组成的处理方式（F5D3，每8天重复一次）被确定为同时降低籽粒中镉和砷的最有效处理方式，与单独的排水处理或淹水处理相比，籽粒镉和砷含量分别降低了80.0%以上和73.1%；这可能与F5D3处理根据其最小“权衡值”（一种用于评估水分管理条件下土壤溶液中砷和镉浓度之间权衡程度的指标）降低溶解态镉和砷的高效率有关，因为籽粒中镉和砷含量的变化与土壤溶液中镉（R = 0.98）和砷（R = 0.92，P = 0.0001）浓度的变化显著相关。此外，籽粒镉含量还与各器官镉含量（尤其是根系镉含量，R = 0.99）以及根 - 茎镉转运因子（R = 0.99）显著相关，而籽粒砷含量与土壤氧化还原电位（R = -0.82，P = 0.003）和pH值（R = 0.88，P = 0.0008）显著相关。F5D3处理下各器官中的氨基酸含量低于淹水和排水处理下的含量。这些结果表明，F5D3处理是同时降低水稻籽粒中镉和砷含量以及氨基酸合成的最有效水分管理策略，这可能是因为水稻无需合成大量氨基酸来螯合金属离子。
