Synergistic Effect of Zinc Oxide, Magnesium Oxide and Graphene Nanomaterials on <i>Fusarium oxysporum</i>-Inoculated Tomato Plants

Tomato is an economically important crop that is susceptible to biotic and abiotic stresses, situations that negatively affect the crop cycle. Biotic stress is caused by phytopathogens such as Fusarium oxysporum f. sp. lycopersici (FOL), responsible for vascular wilt, a disease that causes economic losses of up to 100% in crops of interest. Nanomaterials represent an area of opportunity for pathogen control through stimulations that modify the plant development program, achieving greater adaptation and tolerance to stress. The aim of this study was to evaluate the antimicrobial capacity of the nanoparticles and the concentrations used in tomato plants infected with FOL. To this end, a two-stage experiment was conducted. In Stage 1, the effects of the nanomaterials (Graphene nanoplatelets [GP], Zinc oxide nanoparticles [ZnO NPs], Magnesium oxide nanoparticles [MgO NPs]) were evaluated both alone and in combination to determine the most effective method of controlling FOL-induced disease. In Stage 2, the most effective combination of nanomaterials (ZnO+GP) was evaluated at four concentrations ranging from 100 to 400 mg L−1. To evaluate the effectiveness of the treatments, we determined the incidence and severity of the disease, agronomic parameters, as well as the following biochemical variables: chlorophylls, β-carotene, vitamin C, phenols, flavonoids, hydrogen peroxide, superoxide anion, and malondialdehyde. The results show various positive effects, highlighting the efficiency of the ZnO+GP at 200 mg L−1, which reduced the severity by approximately 20%, in addition to increasing agronomic variables and reducing reactive oxygen species. Moreover, the results show that the application of these nanomaterials increases vegetative development and defense against biotic stress. The use of nanomaterials such as zinc oxide, magnesium oxide and graphene can be an effective tool in the control of the severity of Fusarium oxysporum disease.