Insights into the effect of manganese-based nanomaterials on the distribution trait and nutrition of radish (Raphanus sativus L.).

Manganese (Mn) is one of the essential elements for plant growth and is involved in the process of photosynthesis and seed germination. Herein, we applied two Mn-based nanoparticles, MnO2 and Mn3O4, to the soil to investigate their effects on radish growth, antioxidant system, and nutrients. The radish plant height after treatment with 10 mg/kg of MnO2 and Mn3O4 NPs were increased, compare to the control. In radish's shoot, MnO2 NPs at high concentrations (100 mg/kg) increased MDA activity by 58 % compared to the control group, while exposure to Mn3O4 NPs at the same concentration decreased MDA activity by 14 %. The nutrient content of radishes, such as soluble sugar and vitamin C, was improved. Moreover, single particle inductively coupled plasma mass spectrometry (SP ICP-MS) was used to understand the patterns of migration of Mn-based NPs in radish and subsequent impact on nutrients. We found that Mn-based NPs accumulated mainly in the roots of radish. Interestingly, the accumulation characteristics of MnO2 NPs and Mn3O4 NPs were different. MnO2 NPs accumulated more in radish leaves than in fruits, while the accumulation of Mn3O4 NPs gradually decreased from roots to leaves. Finally, we determined the mineral element content of the leaves, fruits, and roots of radish, and found that the uptake of main metallic mineral elements (e.g. Cu, Fe, Mg, Zn, Na, K) was inhibited by the application of Mn-based NPs. These findings underscore the importance of considering species and multifaceted impacts of Mn-based NPs as nanofertilizers for their wide application in agriculture.

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.