Objetive: Arsenic (As) and fluoride (F) are found in groundwater and soils around the world, causing different problems to crops. Because these elements compete against phosphorus (P) in soils and plants, their relationship is complex. The aim of this work was to study the oxidative stress of soybean plants subjected to different concentrations of As and F, and the effect of P.

Methods: The following 10 treatments were carried out in each of two soils with different P content: three As levels (low 10 mg As kg^-1, medium 50 mg As kg⁻¹ and high 100 mg As kg⁻¹), three F levels (low 160 mg F kg⁻¹, medium 250 mg F kg⁻¹ and high 500 mg F kg⁻¹) and three As + F levels (same concentrations), and the control treatment (soil with the background As and F concentrations) Lipid peroxidation, chlorophyll, gluthatione contents and antioxidant enzymes activities were determination.

Results: Increased lipid peroxidation and alterations in glutathione content, catalase, superoxide dismutase and peroxidase activities as well as in chlorophyll content revealed that As causes higher oxidative stress in plants grown in soils with low P content.

Conclusion: Stress parameters in F treatments were less affected. Plants grown in soils enriched with P revealed a decrease in the toxic effects caused by As and F.

目的：世界各地的地下水和土壤中都含有砷（As）和氟化物（F），对农作物造成不同的问题。由于这些元素与土壤和植物中的磷 (P) 竞争，因此它们的关系很复杂。本工作的目的是研究不同浓度As和F对大豆植株的氧化胁迫以及P的影响。

方法：在两种不同磷含量的土壤中分别进行以下10个处理：三个As水平（低10 mg As kg ^-1，中50 mg As kg ^-1和高100 mg As kg ^-1），三个F水平（低 160 mg F kg ^-1、中 250 mg F kg ^-1和高 500 mg F kg ^-1）和三个 As + F 水平（相同浓度），以及对照处理（具有背景 As 和 F 浓度的土壤） )测定脂质过氧化、叶绿素、谷胱甘肽含量和抗氧化酶活性。

结果：脂质过氧化作用增强，谷胱甘肽含量、过氧化氢酶、超氧化物歧化酶和过氧化物酶活性以及叶绿素含量发生变化，表明砷会对低磷含量土壤中生长的植物造成更高的氧化应激。

结论： F处理中的应激参数受影响较小。在富含磷的土壤中生长的植物显示出砷和氟引起的毒性作用降低。