To overcome the drawbacks of the Vicia faba root tip micronucleus test in soil using the solution extract method, we conducted a potting experiment by direct soil exposure. Cadmium was spiked into 3 typical soils (brown soil, red soil, and black soil) to simulate environmental concentrations (0.625, 1.25, 2.5, 5, and 10 mg kg-1). Multiple Vicia faba tissues (primary root tips, secondary root tips, and leaf tips) were sampled, and mitotic index (MI), chromosome aberration frequency (CA), and micronucleus frequency (MN) were used as endpoints after a seedling period of 5 days. The results showed a response between Cd concentrations and multiple sampling tissues of Vicia faba, and the secondary root tips responded to Cd stress the most, followed by primary root tips and leaf tips. Soil physicochemical properties (e.g., pH, total phosphorus, total organic carbon, etc.) influenced the genotoxicity of Cd, and pH was the dominant factor, which resulted in the genetic toxicity response of Cd in soils in the order: red soil > brown soil > black soil. The lowest observable effect concentration (LOEC) of Cd was 1.25 mg kg-1 for both brown soil and red soil and 2.5 mg kg-1 for black soil. In view of this, we suggested that soil properties should be considered in evaluating genotoxicity risk of Cd in soil, especially with soil pH range, and the secondary root tips should be taken as suitable test tissues in the MN test due to its more sensible response feature to Cd stress in soil.

中文翻译：

---

以直接暴露于土壤和微核试验为特征，蚕豆幼苗对土壤中镉的遗传毒性反应。

为了克服使用溶液提取法在土壤中进行的蚕豆根尖微核试验的弊端，我们通过直接暴露于土壤中进行了盆栽试验。将镉掺入3种典型土壤（棕色土壤，红色土壤和黑色土壤）中，以模拟环境浓度（0.625、1.25、2.5、5和10 mg kg-1）。取样5个苗期后，取样多个蚕豆蚕丝组织（主要根尖，次要根尖和叶尖），并以有丝分裂指数（MI），染色体畸变频率（CA）和微核频率（MN）作为终点天。结果表明，镉浓度与蚕豆的多个采样组织之间存在响应，次生根尖对镉胁迫的响应最大，其次是根尖和叶尖。土壤理化特性（例如pH值，总磷，总有机碳等）影响镉的遗传毒性，pH是主要因素，导致土壤中镉的遗传毒性响应顺序为：红土>棕壤>黑土。Cd的最低可观察到的有效浓度（LOEC）对于棕色土壤和红色土壤均为1.25 mg kg-1，对于黑色土壤为2.5 mg kg-1。有鉴于此，我们建议在评估土壤中镉的遗传毒性风险时应考虑土壤特性，尤其是在土壤pH范围内，并且由于其更敏感的反应，次生根尖应被视为MN试验中的合适试验组织。土壤中镉胁迫的特征。Cd的最低可观察到的有效浓度（LOEC）对于棕色土壤和红色土壤均为1.25 mg kg-1，对于黑色土壤为2.5 mg kg-1。有鉴于此，我们建议在评估土壤中镉的遗传毒性风险时应考虑土壤特性，尤其是在土壤pH范围内，并且由于其更敏感的反应，次生根尖应被视为MN试验中的合适试验组织。土壤中镉胁迫的特征。Cd的最低可观察到的有效浓度（LOEC）对于棕色土壤和红色土壤均为1.25 mg kg-1，对于黑色土壤为2.5 mg kg-1。有鉴于此，我们建议在评估土壤中镉的遗传毒性风险时应考虑土壤特性，尤其是在土壤pH范围内，并且由于其更敏感的反应，次生根尖应被视为MN试验中的合适试验组织。土壤中镉胁迫的特征。