Effects of two Mn-based nanomaterials on soybean antioxidant system and mineral element homeostasis

Since less attention has been paid to the physiological effects of manganese-based nanomaterials (Mn-based NMs) on plants, it is necessary to explore the application of Mn-based NMs in improving crop yield and the concentration range of Mn-based NMs that produce toxicity. The results showed that soil application of 100 mg/kg manganese oxide (MnO₂) and manganese tetroxide (Mn₃O₄) NMs could increase the shoot height of soybean by 51.8% and 31.8%, respectively, compared with the control. In addition, 100 mg/kg MnO₂ NMs increased catalase (CAT) activity in roots by 62.2%, and 50 mg/kg Mn₃O₄ NMs increased CAT activity in roots by 200%, thereby increasing the stress resistance of soybean. However, at the highest concentration of 500 mg/kg, Mn-based NMs increased the Mn content in soybean extremely so that the absorption of mineral elements such as potassium, phosphorus, and calcium in the root was inhibited. This research lays the foundation for the safe application of Mn-based NMs in agriculture, benefiting the development of nanotechnology and agriculture globally.