Abstract
Cadmium (Cd) is highly toxic to living organisms and the contamination of Cd in paddy soil in China has received much attention. In the present study, by conducting pot experiment, the influence of S fertilizer (S0) on rice growth, iron plaque formation, Cd accumulation in rice plants and bacterial community in rice rhizosphere soil was investigated. The biomass of rice plants was significantly increased by S0 addition (19.5–73.6%). The addition of S0 increased the formation of iron plaque by 24.3–45.8%, meanwhile the amount of Cd sequestered on iron plaque increased. In soil treated with 5 mg/kg Cd, addition of 0.2 g/kg S0 decreased the diffusive gradients in thin films (DGT) extractable Cd by 60.0%. The application of S0 significantly decreased the concentration of Cd in rice grain by 12.1% (0.1 g/kg) and 36.6% (0.2 g/kg) respectively. The addition of S0 significantly increased the ratio of Acidobacteria, Bacteroidetes in rice rhizosphere soil. Meanwhile, the ratio of Planctomycetes and Chloroflexi decreased. The results indicated that promoting Fe- and S-reducing and residue decomposition bacterial in the rhizosphere by S0 may be one biological reason for reducing Cd risk in the soil-rice system.
Highlights
Cadmium (Cd) is highly toxic to living organisms and the contamination of Cd in paddy soil in China has received much attention
Rice is mostly grown under flooding conditions and formation of CdS in paddy soil is an significant way to reduce the bioavailability of Cd5, providing implication of using sulfur to regulate the mobility of Cd in paddy soil
The influence of sulfur fertilizer on Cd biogeochemical behavior in soil, accumulation in rice plants and microbial community in soil was investigated in the present study
Summary
Cadmium (Cd) is highly toxic to living organisms and the contamination of Cd in paddy soil in China has received much attention. Rice is mostly grown under flooding conditions and formation of CdS in paddy soil is an significant way to reduce the bioavailability of Cd5, providing implication of using sulfur to regulate the mobility of Cd in paddy soil. Besides the reduction of Cd bioavailability in paddy soil, the sequestration of Cd by iron plaque formed on the surface of rice roots is another way to decrease the uptake of Cd by rice plants. Application of sulfur fertilizer can be one way to reduce Cd uptake by rice plants due to the sequestration of Cd by the enhanced formation of iron plaque[11]. Sulfur has the potential of reducing Cd bioavailability by formation of CdS and enhancing Cd sequestration by inducing iron plaque formation in paddy soil, making sulfur fertilizer a promising candidate for remediation of Cd contaminated paddy soil. The interactions between sulfur fertilizer, iron plaque formation, Cd bioavailability and Cd accumulation in rice are still unclear
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