Copper Nanomaterial Morphology and Composition Control Foliar Transfer through the Cuticle and Mediate Resistance to Root Fungal Disease in Tomato (Solanum lycopersicum)

Two copper nanomaterials (CuO nanoparticles [NPs] and Cu3(PO4)2·3H2O nanosheets) and CuSO4 were applied to tomato (Solanum lycopersicum) leaves, and elemental Cu movement from the leaf surface through the cuticle and into the interior leaf tissue was monitored over 8 h. Two forms of nanoscale Cu were used to foliar treat tomato on a weekly basis in greenhouse and field experiments in the presence of the pathogen Fusarium oxysporum f. sp. lycopersici. For CuSO4, Cu accumulation and retention in the cuticle was over 7-fold greater than the nanomaterials, demonstrating that nanoscale morphology and composition mediate Cu accumulation in leaf tissue. In the greenhouse, weekly foliar applications of the nanosheets and NPs increased seedling biomass by 90.9 and 93.3%, respectively, compared to diseased and ionic Cu controls. In the field, Cu3(PO4)2·3H2O nanosheets reduced disease progress by 26.0% and significantly increased fruit yield by over 45.5% per plant relative to the other treatments in diseased soil. These findings suggest that nanoscale nutrient chemical properties can be tuned to maximize and control movement through the cuticle and that interactions at the seedling leaf biointerface can lead to season-long benefit for tomato growing in the presence of Fusarium spp.