Novel properties of nanoparticles (NPs) can be leveraged to make agriculture more efficient and sustainable. Specifically, engineering NP surfaces to target plant leaves and selected entry points for pathogens can improve the efficacy and efficiency of pesticides and nutrient delivery. However, there is little understanding of the properties of NPs that promote adhesion to specific leaf features, and that influence their uptake, and translocation within the plants.<br/>In this study, we foliarly exposed a known amount of Au-NP to young wheat plants for 1 week. The Au-NP had different sizes (3.5, 12 and 50nm in diameter) and different coatings were used to vary for the hydrophobicity of the NP. Plant health traits as respiration and photosynthesis of the plant were also measured before and after exposure. The attachment on the leaves, the uptake by the leaves and the translocation within the plant of Au-NP by was assessed using ICP-MS on different parts of the plants. The interaction of Au-NP and leaves was further investigated using enhanced dark-field microscopy, and the differential paths of entries of the Au-NP were characterized using µ-XRF mapping.<br/>Results indicate that both the size and the coating of the NP impact their entrance in the plants and to their gas respiration and photosynthesis yields. While for the same kind of coating the biggest particles translocate at a lower extent, the coatings significantly modulated these effects. Indeed, hydrophilic (citrate) coating allowed for a higher translocation to the upper part of the plant (leaves and stem younger than the exposed leaves), hydrophobic-coated nanoparticle accumulated at a higher level to the lower part of the plant (older than the exposed leaf). Finally, all the Au-NP translocated to different extents to the roots and the 3.5 and 12 nm Au-NP were released into the soil, albeit adhered to the roots.<br/>Further investigations need to be done to better understand by which mechanisms the coating can influence the translocation and the accumulation of Au-NP, and if these phenomena are observed for different plant architectures. However, these findings open the door to the use of nano-phases in the agriculture as a way of delivery molecules or particles at a chosen part of a plant.

Elucidating nanoparticle-plant leaf interactions, uptake, and mobility for designing highly efficient foliar-applied agrochemicals

255th National Meeting (2018)

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