Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Sci Total Environ. 2024 Dec 10;955:177068. doi: 10.1016/j.scitotenv.2024.177068. Epub 2024 Oct 22.
Arsenic (As) methylation is an important component of As biogeochemical cycle. Microbial As methylation is enhanced under anoxic conditions in paddy soil, producing dimethylarsenate (DMA) which can cause physiological straighthead disease in rice. We conducted field experiments at two sites to test the effect of midseason draining of paddy water on microbial As methylation and the incidence of straighthead disease. Compared to continuous flooding, midseason draining increased soil Eh, decreased the abundances of microbial genes for arsenate reduction (arsC and arrA) and arsenite methylation (arsM), and lowered the concentrations of both inorganic As and DMA in soil porewater. Draining shifted microbial composition, resulting in decreases in the relative abundance of 17-132 amplicon sequence variants. Draining decreased the accumulation of DMA in rice husk and of inorganic As and DMA in rice grain, decreased the incidence of straighthead disease, and increased grain yield by 20-45 %. Further experiments were conducted at eight field sites to assess the effect of midseason draining in a split field design. Draining decreased husk DMA concentration by 40-65 % and increased grain yield by 25-209 %. This study demonstrates that midseason draining can effectively suppress microbial As methylation and alleviate rice straighthead disease, benefiting both grain yield and safety.
砷（As）甲基化为砷生物地球化学循环的重要组成部分。在稻田缺氧条件下，微生物砷甲基化作用增强，产生二甲基砷酸（DMA），这可能导致水稻出现生理性直头病。我们在两个地点进行了田间试验，以测试稻田中期排水对微生物砷甲基化和直头病发病率的影响。与连续淹水相比，中期排水增加了土壤 Eh 值，降低了砷酸盐还原（arsC 和 arrA）和亚砷酸盐甲基化（arsM）的微生物基因丰度，并降低了土壤孔隙水中无机砷和 DMA 的浓度。排水改变了微生物组成，导致 17-132 个扩增子序列变异体的相对丰度降低。排水减少了稻壳中 DMA 的积累，减少了稻谷中无机砷和 DMA 的积累，降低了直头病的发病率，使粮食产量增加了 20-45%。进一步在八个田间地点进行了分场设计的田间试验，以评估中期排水的效果。排水使稻壳 DMA 浓度降低了 40-65%，使粮食产量增加了 25-209%。本研究表明，中期排水可有效抑制微生物砷甲基化作用，缓解水稻直头病，有利于提高粮食产量和安全性。
