Material augmented plant development

Abstract

Upconversion nanoparticles (UCNPs) have been studied thoroughly in the last decade for use in fields such as security and bioimaging. Toxicology and translocation of UCNPs were previously tested in plants, however no research was carried out to observe the effects of UCNPs to the photosynthetic rate of plants. In addition, translocation after foliar application has never been studied. Here, the effect of NaYF4:Yb,Tm UCNPs on the chlorophyll content and translocation of Solanum lycopersicum was studied. NaYF4:Yb,Tm UCNPs were prepared using hydrothermal autoclave synthesis with either pure trisodium citrate dihydrate or a trisodium citrate dihydrate and lauric acid cosurfactant system. UCNPs obtained were either submicron-sized of hexagonal phase or nano-sized of cubic phase. Leaves of the plants were coated with varying concentrations of each set of UCNPs, after which the chlorophyll content was measured over a two-week period. This study showed that UCNPs promote plant development, and that the difference in size and concentration of the UCNPs play a significant role in the chlorophyll content. The higher concentrations of UCNPs had a more positive effect compared to a lower concentration of similarly sized UCNPs, and nano-sized UCNPs fared better compared to submicron-sized UCNPs. Confocal imaging of the leaves showed an even spread of UCNPs 3 hours after application, and an insignificant change in location after 5 days.