Positive effects of metallic nanoparticles on plants: Overview of involved mechanisms

Engineered nanoparticles (NPs) are considered as potential agents for agriculture as fertilizers, growth enhancers and pesticides. Therefore, understanding the mechanisms that are responsible for their effects is important. Various studies demonstrated that the application of nontoxic concentrations can promote seed germination, enhance plant growth and increase the yield. Moreover, NPs can be used to protect plants from environmental impacts such as salt or drought stress and diminish accumulation and toxicity of heavy metals. NPs can serve as a source of micronutrients (e.g. ZnO, iron- and manganese-based NPs), thus increasing fitness and helps plants to cope with stress conditions. TiO2 and iron-based NPs are able to delay senescence and speed-up cell division via changes in phytohormonal levels. The application of some NPs can promote the activity of enzymes such as amylase, nitrate reductase, phosphatase, phytase and carbonic anhydrases, which are involved in metabolism and nutrient acquisition. E.g. ZnO and TiO2 NPs can stimulate chlorophyll biosynthesis and photosynthetic activity. Iron-based and CeO2 NPs enhance stomata opening resulting in better gas exchange and CO2 assimilation rate. NPs can also modulate oxidative stress by the stimulation of the antioxidant enzymes such peroxidases and superoxide dismutase. However, the knowledge about the fate, transformation, and accumulation of NPs in the environment and organisms is needed prior to their use in agriculture to avoid negative environmental impacts. Higher or lower toxicity of various NPs was established for microorganisms, plants or animals. In this overview, we focused on the possible mechanisms of Ag, ZnO, TiO2, Fe-based, CeO2, Al2O3, and manganese-based NPs responsible for their positive effects on plants.

Automated summary

Engineered nanoparticles have potential applications in agriculture as fertilizers, growth enhancers, and pesticides. They can promote seed germination, enhance plant growth, protect plants from stress, and modulate physiological processes in plants. By stimulating enzyme activity, regulating plant hormone levels, and improving gas exchange, nanoparticles positively affect plant health and productivity.