Cadmium (Cd) contamination of rice is a serious public health concern in certain parts of the world. Amendment application based on local organic materials (e.g., manures, compost) is considered effective for reducing plant-available Cd in soil. In this study, two Thai rice (Oryza sativa L) varieties, Chorati and Mali Daeng, were grown in Cd-contaminated soil amended with cow manure, pig manure, organic fertilizer, and leonardite in a mesocosm system. Organic amendment treatments reduced Cd availability in soil. Specific effects of amendments were a function of amendment type and rice variety. Cow manure and leonardite substantially increased growth of the Mali Daeng variety in Cd-contaminated soils; however, there was no significant effect on total biomass of Chorati. Leonardite significantly enhanced grain production of Chorati (12.2 g plant⁻¹) and reduced Cd content in rice grain to 0.14 mg kg⁻¹ which is considered safe for consumption. Leonardite increased CEC in contaminated soil which helped reduce Cd bioavailability to plants. Both rice varieties had ‘excluder potential,’ as they accumulated Cd primarily in roots with translocation factor (TF) values < 1. Root anatomical analysis revealed that leonardite and pig manure treatments increased metaxylem vessel area, which could result in the enhancement of TF in the Chorati variety. However, any increase in TF was not associated with Cd content in rice grains. Our findings indicate that organic amendments immobilized Cd in soil and enhanced rice growth and production while reducing Cd content in rice grain. We emphasize here that the selection of cultivars and amendments plays a key role in the success of low-Cd rice production.

中文翻译：

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利用有机修正剂固定镉在污染土壤中的作用及其对水稻生长性能的影响

大米中的镉（Cd）污染是世界某些地区严重的公共卫生问题。基于局部有机材料（例如肥料，堆肥）的修正应用被认为对减少土壤中植物可利用的镉有效。在这项研究中，两种泰国大米（Oryza sativaL）变种Chorati和Mali Daeng在中膜系统中生长在Cd污染的土壤中，土壤中掺有牛粪，猪粪，有机肥料和变绿石。有机修正处理降低了土壤中Cd的利用率。修正的具体效果取决于修正类型和水稻品种。牛粪和锂长石大大增加了受镉污染的土壤中马里达恩品种的生长；但是，对Chorati的总生物量没有显着影响。芒硝显着提高了Chorati（12.2 g plant ^-1）的谷物产量，并将稻米中的Cd含量降低至0.14 mg kg ^-1被认为可以安全食用。芒硝增加了受污染土壤中的CEC，这有助于降低Cd对植物的生物利用度。两种水稻品种均具有“排泄潜力”，因为它们主要在转运因子（TF）值小于1的根中积累Cd。根解剖学分析表明，莱乐土和猪粪处理增加了后木质部的血管面积，这可能导致TF的增强。 Chorati品种。但是，TF的任何增加都与稻米中Cd的含量无关。我们的发现表明，有机改性剂可将Cd固定在土壤中，并在减少稻谷中Cd含量的同时提高水稻的生长和产量。我们在此强调，选择栽培品种和改良剂对低镉水稻生产的成功至关重要。