Exploring Potential Use of ZnO Nanoparticles to Enhance Zn Nutrition in Wheat (Triticum aestivum).

Zinc deficiency in wheat (Triticum aestivum) could compromise yield and zinc concentrations in grain.  Inadequate zinc content in wheat is associated with zinc malnutrition, which occurs in about one third of world human population. In this experiment, we explored the potential use ZnO nanoparticles (NPs) with various engineered surface chemistries as a Zn fertilizer for Pembroke winter wheat. We synthesized bare ZnO NPs, electrostatically stabilized ZnO-Zn₃(PO₄)₂ core-shell NPs (core-shell), sterically stabilized ZnO NPs with dextran (Dex-ZnO), and electrosterically stabilized ZnO NPs with dextran sulfate (Dex(S)-ZnO) and fully characterized their physicochemical properties. Seeds were allowed to imbibe suspensions/solutions of the abovementioned ZnO NPs in addition to ZnSO₄, bulk ZnO, and control treatments overnight. We germinated the seeds on a pre-moistened filter paper in Petri dishes, which were kept in the dark at 25°C until 65% of seeds in control treatments developed a radicle root of at least 20 mm length. We measured percent germination, radicle root and shoot length, dry biomass and Zn concentration in roots and shoots. There was a significant negative effect of ZnSO₄ on germination success. For ZnSO₄ and all ZnO NP treatments, Zn concentrations in roots and shoots were significantly correlated (α=0.05) with Zn concentration in the exposure solution. Overall, greater tissue concentrations of Zn could be obtained when exposing seeds to ZnO materials without causing toxicity (decreased germination success) when compared to ZnSO₄, which is conventionally used as a fertilizer. Dex-ZnO and ZnO NPs achieved the highest Zn concentrations in roots and shoots, respectively without decreasing biomass.