Effects of Optimized Water Management on the Uptake and Translocation of Cadmium and Arsenic in Oryza Sativa L. In Two Contaminated Soils

Pot experiments were conducted 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 treatment consisting of five days of flooding followed by three days of drainage (F5D3, repeated every eight 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”, due to the variations in grain Cd and As contents were significantly correlated with the variations in soil solution Cd (R2 = 0.98) and As (R2 = 0.92, p = 0.0001) concentrations. Additionally, grain Cd content was also significantly related to the organs Cd contents (especially root Cd content, R2 = 0.99) and the root-to-shoot Cd translocation factors (R2 = 0.99), whereas grain As content was significantly related to soil Eh (R2=-0.82, p = 0.003) and pH (R2 = 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.