Effective phytoremediation of manganese (Mn) requires the careful selection of a species that has a relatively high manganese tolerance. Exploring the physiological mechanisms related to Mn stress responses is crucial for identifying and employing species for Mn phytoremediation. Xanthium strumarium is a species that can accumulate high levels of Mn, thus it is a candidate species for Mn-phytoremediation. To reveal the tolerance mechanisms of this species to manage Mn stress, the morphological, physiological, and biochemical responses of seedlings grown in water cultures under six different Mn concentrations were analyzed. The results showed that X. strumarium can accumulate high levels of Mn, even as plant growth was inhibited by rising Mn concentrations. Malondialdehyde (MDA) content increased and catalase (CAT) activity decreased along with the increased Mn concentrations, while soluble protein and proline content, as well as the superoxide dismutase (SOD) and peroxidase (POD) enzymes, all increased initially and then declined. The highest value of POD, SOD, soluble protein and proline all occurred at 5000 µM of Mn stress, which means that X. strumarium can adapt to low concentration of Mn stress. The net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci) and transpiration rate (Tr) decreased, and the stomatal limitation (Ls) increased in response to Mn stress. Furthermore, water use efficiency (WUE) and intrinsic water use efficiency (WUEi) increased first under low concentration of Mn, and then reduced as the concentration of Mn increased. The maximum quantum efficiency of PSII photochemistry (Fv/Fm), efficiency of excitation capture by open PSII reaction centers (Fv′/Fm′), electron transport rate (ETR) declined as Mn concentration increased. In conclusion, the above results showed that X. strumarium can be effectively used for phytoremediation of Mn-contaminated soils.

锰（Mn）的有效植物修复需要精心选择具有较高锰耐受性的物种。探索与锰胁迫反应有关的生理机制对于鉴定和利用物种进行锰植物修复至关重要。Xanthium strumarium是可以积累大量Mn的物种，因此它是Mn植物修复的候选物种。为了揭示该物种应对锰胁迫的耐受机制，分析了在六种不同锰浓度下水培养中生长的幼苗的形态，生理和生化响应。结果表明，X。strumarium即使植物生长受到锰浓度升高的抑制，它也可以积累高水平的锰。丙二醛（MDA）含量增加，过氧化氢酶（CAT）活性随Mn浓度增加而降低，而可溶性蛋白质和脯氨酸含量以及超氧化物歧化酶（SOD）和过氧化物酶（POD）酶均先升高后降低。POD，SOD，可溶性蛋白和脯氨酸的最高值均出现在Mn胁迫为5000 µM时，这意味着X. strumarium可以适应低浓度的Mn胁迫。净光合速率（Pn），气孔导度（Gs），细胞间CO ₂浓度（Ci）和蒸腾速率（Tr）减少，气孔限制（Ls）响应Mn胁迫而增加。此外，水分利用效率（WUE）和内在水分利用效率（WUEi）在低浓度的锰下首先增加，然后随着锰浓度的增加而降低。随着Mn浓度的增加，PSII光化学的最大量子效率（Fv / Fm），开放PSII反应中心激发捕获的效率（Fv'/ Fm'），电子传输速率（ETR）下降。总之，以上结果表明，X。strumarium可以有效地用于锰污染土壤的植物修复。