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| Effects of split silicon application on the fractions of Cd in soil and its accumulation in rice |
| Received:January 23, 2018 |
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| KeyWord:rice;silicon;fractions of cadmium;transport;accumulation |
| Author Name | Affiliation | E-mail | | HE Min-jie | Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | CAI Kun-zheng | Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | WANG Wei | College of Agriculture, South China Agricultural University, Guangzhou 510642, China | | | HUANG Fei | Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | | | CAI Yi-xia | Key Laboratory of Agro-Environment in the Tropics, Ministry of Agriculture, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China | caiyixia@scau.edu |
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| Abstract: |
| The aims of this study are to investigate the influences of silicon application on the migration of cadmium in soil-rice(Oryza sativa L.)systems and to explore the optimal timing and ratio of silicon application for alleviating the uptake and accumulation of Cd in Cdcontaminated soil. A pot experiment was carried out to study the effects of silicon application at different stages on the fractions of Cd in soil and on the uptake, transport, and accumulation of Cd in rice. Cadmium chloride was added to simulate polluted soil with a Cd content of 100 mg·kg-1. Based on the same total amount of silicon application(56 mg·kg-1), three kinds of silicon application methods were designed:silicon applied as basal fertilizer(C1), silicon applied as basal fertilizer and at jointing stages with a ratio of 1:1(C2), and silicon applied at jointing stages(C3). No silicon application was used as the control(CK). The results showed the Cd contents in soil at the mature stage increased by 19.4%(P<0.05)and 18.9%(P<0.05)with the C2 and C3 treatments, respectively, compared to the CK levels. The exchangeable Cd contents in soil with C2 and C3 treatments decreased by 27.3%(P<0.05)and 27.1%(P<0.05), respectively, whereas the residual Cd contents in soil increased by 97.7%(P<0.05)and 111.3%(P<0.05), respectively. The Cd contents in roots and the aleurone layer treated with silicon at maturity were elevated significantly, whereas those in stems, leaves, and white polished rice were lower. Furthermore, the Cd contents in the white rice were lower by 13.8%(P<0.05), 35.1%(P<0.05), and 27.9%(P<0.05)with C1, C2, and C3 treatments, respectively, compared to the CK levels. The transfer factors and bioconcentration enrichment factor(BEF)of Cd in stems, leaves, and polished rice at the mature stage were reduced by silicon application. However, the BEF of Cd in roots was increased. Furthermore, there was a significant correlation between the content of different fractions of Cd in soil and Cd accumulation in roots and polished rice. In summary, soil Cd availabilities with the C2 and C3 treatments at the mature stage were reduced, whereas residual Cd were significantly increased with silicon application. The transfer of Cd from the soil to the rice plant was inhibited, and much of the Cd absorbed by the rice was deposited in roots, which reduced the migration of Cd to aboveground. Consequently, the content and accumulation of Cd in white rice were decreased explicitly and those in polished rice were significantly decreased. In addition, C2 treatment was more effective for reducing the content of reducible Cd in soil throughout the growth period, increased the content of oxidizable Cd in soil at the heading stage, and promoted the growth and development of rice before the heading stage. The effect of C2 treatment was the best, and thus was recommended for practical use. |
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