College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Agricultural & Rural Pollution Abatement and Environmental Safety, Guangzhou 510642, China.
Sci Total Environ. 2023 Dec 15;904:167383. doi: 10.1016/j.scitotenv.2023.167383. Epub 2023 Sep 26.
Rice straw incorporation is globally recognized as a viable alternative to incineration. However, it might lead to arsenic (As) methylation in soils, resulting in increased accumulation of methylated As in rice plants, potentially contributing to the emergence of rice straighthead disease. To evaluate the effect of straw incorporation on the As transformation in the paddy field system, we conducted a pot experiment for rice cultivation in two paddy soils with different As background levels and also characterized the response of the soil microbial community to straw incorporation. The results showed that straw incorporation elevated the total and methylated As concentration within the soil solution and rice plants, which in turn reduced rice seed setting rate and yield, and caused straighthead disorder in rice cultivated in soils with high As levels. 16S rRNA-based sequencing demonstrated reduced abundance and diversity of microorganisms upon adding straw. Notably, the dominant phylum, Bacteroidetes, exhibited a significant increase in abundance due to straw integration, while the abundance of Proteobacteria and Acidobacteria decreased. At the family level, the prevalence of Rikenellaceae increased only in soils contaminated with As following straw incorporation. Redundancy analysis showed positive associations between Rikenellaceae and levels of methylated As present in both soil porewater and rice husks, suggesting a potentially pivotal role of Rikenellaceae in the As methylation process after straw integration. These findings collectively emphasize that including straw can reshape the soil's microbial community and amplify As methylation in the soil, thereby promoting the uptake and accumulation of methylated As in rice and inducing straighthead disease in As-contaminated soil.
稻草还田在全球范围内被认为是一种可行的替代焚烧的方法。然而，它可能导致土壤中砷（As）的甲基化，从而导致水稻植株中甲基化 As 的积累增加，这可能导致水稻直穗病的出现。为了评估稻草还田对稻田系统中 As 转化的影响，我们在两种具有不同 As 背景水平的稻田土壤中进行了水稻栽培的盆栽实验，同时还研究了土壤微生物群落对稻草还田的响应。结果表明，稻草还田增加了土壤溶液和水稻植株中总砷和甲基化砷的浓度，从而降低了水稻结实率和产量，并导致高 As 土壤中栽培的水稻出现直穗紊乱。基于 16S rRNA 的测序表明，添加稻草后微生物的丰度和多样性降低。值得注意的是，优势门（Bacteroidetes）的丰度因稻草整合而显著增加，而 Proteobacteria 和 Acidobacteria 的丰度则减少。在科水平上，仅在含有 As 的土壤中，添加稻草后 Rikenellaceae 的丰度增加。冗余分析表明，Rikenellaceae 与土壤孔隙水中和稻壳中存在的甲基化 As 水平之间存在正相关关系，这表明在稻草整合后，Rikenellaceae 可能在 As 甲基化过程中发挥关键作用。这些发现共同强调了稻草的添加可以重塑土壤微生物群落并放大土壤中 As 的甲基化，从而促进水稻对甲基化 As 的吸收和积累，并在 As 污染土壤中诱导直穗病。
