This study examined the effects of applying silver nanoparticles (AgNPs; 0, 5 and 10 mg L¿1) in a hydroponic system for seven days on growth parameters and on nutrient and phytohormone concentrations in two tomato cultivars, Vengador and Rio Grande. The results indicated that AgNPs at concentrations of 5 and 10 mg L¿1 did not change leaf number, stem length, or fresh/dry biomass weight. In leaves of Vengador, P and K concentrations decreased, while Mg and S increased in response to AgNPs. In stems and roots, both P and K decreased. Zn concentrations increased in leaves, Mn in stems and roots. In leaves of Rio Grande, K, Mg, S, Cu and Mn concentrations increased, while P decreased in AgNP-treated plants, as compared to the control. In stems, N, S and Mn concentrations increased, but P, K, Ca, Mg and B decreased. In roots, P, K, Ca, Mg, Cu, Zn, Mn and B decreased, whereas S increased. Silver was only detected in roots of plants treated with AgNPs in both cultivars under study. In leaves of Rio Grande plants, kinetin concentrations decreased with AgNPs applications. In roots of Vengador, indole-acetic acid concentrations increased with 10 mg AgNP L¿1; in Rio Grande, roots exhibited an increased concentration of gibberellic acid and abscisic acid in plants exposed to 5 mg AgNP L¿1. The evidence retrieved from this work unveils the impact of metal-based NMs on the modulation of nutrient and phytohormone concentrations in a so important food crop such as tomato.
