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| Effects of different passivating agents on cadmium uptake and accumulation in rice and its timeliness under field conditions |
| Received:June 28, 2022 |
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| KeyWord:passivating agent;cadmium;rice;uptake and accumulation;time-effectiveness |
| Author Name | Affiliation | E-mail | | HUANG Yanfei | Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | | | CHEN Guifen | Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | | | HUANG Yuyi | Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | | | XIONG Liumei | Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | | | LIU Shuyi | Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | | | ZHONG Huimei | Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | | | LIU Bin | Agricultural Resource and Environment Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China | 476985375@qq.com |
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| Abstract: |
| This study was conducted to study the effects of different passivating agents and their combinations on cadmium uptake and accumulation in rice, and their time-effectiveness under field conditions. A field experiment was conducted to study the effects of mulberry stem biochar, oyster shell powder, bentonite and silkworm sand, and their combinations on soil pH, soil available cadmium content, and cadmium contents in different parts of rice plants, as well as their time-effectiveness. The results showed that the passivating agents increased the pH value of soil, with oyster shell powder（O）increasing the pH the most. The soil available cadmium content was significantly decreased（P<0.05）, with the combination of mulberry stem biochar and shell powder and silkworm sand（MOS）decreasing Cd content the most by 38.25%, 34.24%, and 14.60% in three seasons respectively. Cadmium content in the root, straw, chaff, and brown rice decreased significantly. MOS treatment decreased cadmium content in brown rice the most, which decreased by 49.04%, 54.31%, and 25.22% in three seasons respectively, but still did not meet the national standard of 0.2 mg·kg-1 Cd content. The bioconcentration factor of cadmium in root, straw, chaff, and brown rice decreased significantly. The transfer factor of cadmium from the root to straw（TFstraw/root）and the transfer factor of cadmium from chaff to brown rice（TFbrown rice/chaff）decreased significantly; among them, MOS treatment had the best effect. As the application time reached the third season, the decrease efficiency of cadmium content in brown rice of passivating agents decreased significantly; among them, bentonite（B）, silkworm（S）, and MOS treatments were comparatively small. Correlation analysis showed that cadmium content in brown rice was significantly negatively correlated with soil pH（P<0.01）and significantly positively correlated（P<0.01）with soil available cadmium content, TFstraw/root, TFbrown rice/chaff, and cadmium content in rice root, straw, and chaff. A comprehensive evaluation revealed that the decrease efficiency and time-effectiveness of MOS treatment were comparatively better than that of other treatments, thus making it an ideal candidate for use in production practice. However, to ensure the cadmium content in rice meet the requirements of the national food safety standard limits of contaminants in food（GB 2762—2017）, other remediation measures should be applied under the condition of soil cadmium content 1.5 mg·kg-1, and passivating agents should be added at the right time to ensure its passivating effect after the second season. |
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