[Effect of Conditioning Agent Combined with Flooding Measures on Absorption and Accumulation of Cadmium in Rice].

In order to evaluate the effects and mechanisms of flooding measures, soil conditioner, silicon mineral fertilizer and sprayed foliar fertilizer, gypsum powder, and their multiple treatments for reducing Cd accumulation in rice grown in Cd-contaminated soil. A plot experiment was conducted in three different Cd-contaminated soils. The results showed that flooding measures, a single application of conditioning agents, and combined application and flooding treatment can reduce soil-available Cd and the Cd content in various organs of rice with 6.58%-30.01% reduction in soil available-Cd and 12.64%-68.68% reduction in Cd content in brown rice, respectively. The Cd reduction decreased in the following order:comprehensive treatment (T6) > basic application of gypsum powder (T5) > base Xiangrunbang state soil conditioner (T3) > mineral silicon fertilizer and spray foliar fertilizer (T4) > flood treatment (T2). In addition, the average value of the reduction effect of the Cd content in brown rice was calculated. The five treatments in the experiment reduced the enrichment of various parts of the rice, which is a main reason for the decrease in Cd content in the brown rice. According to the field plot test, the combined application of the basic conditioning agent, mineral silicon fertilizer, and sprayed foliar fertilizer, and gypsum powder and flooding measures can be used as an effective method for Cd pollution control in Cd-contaminated cultivated rice.

[Bioavailability of Silicon Fertilizer Coupled Water Management on Soil Bioavailability and Cumulative Control of Rice in Compound Contaminated Paddy Soils].

The effect of wet irrigation (CK), agronomic measure flooding (WF), instantaneous silicon fertilizer combined with flooding measures (FYsi), mineral silicon fertilizer combined with flooding measures (FKsi), and a mix of two kinds of silicon fertilizer combined with flooding measures (FYK) on the bio-availability of As and Cd in soil and the accumulation of As and Cd in rice were investigated by pot experiments. The results showed that the pH of the soils combined with flooding measures was increased by 0.12-0.72 units with similar trends of an increase and then a decrease before finally become neutral. The Eh of the soil combined with flooding was significantly decreased, but the Eh of soil after flooding treated by FYsi, FKsi, and FYK combined with the flooding was significantly higher than that treated by WF, and the content of Cd in brown rice was reduced by 38.83%-65.05% compared with that treated by CK. The WF and FYK treatments can significantly reduce the accumulation of Cd in brown rice, resulting in the lowest Cd contents in brown rice of 0.98 and 0.72 mg·kg-1, respectively. The contents of As in brown rice treated by FYsi, FKsi, and FYK were decreased by 23.80%, 38.10%, and 47.62%, respectively, compared with that with the CK treatment, except that the content of As in brown rice treated by WF increased by 36.64%. FYsi and FYK treatments had the best inhibitory effect on the accumulation of As in brown rice, with the lowest As contents of 0.13 mg·kg-1 and 0.11 mg·kg-1 in brown rice (P <0.01), respectively. There was an extremely significant correlation between the contents of extractable Cd and the total content of Cd in the brown rice (P <0.05), and there was no significant difference between the contents of extractable As and the total content of As in the brown rice. Therefore, FYsi, FKsi, and FYK can effectively inhibit the accumulation of Cd and As in rice grown in Cd-As compound polluted soil, and FYK showed the best performance.