Physiological response of tomato plants grown in saline and non-saline soils to foliar application of SiO2/TiO2 nanocomposites

Abstract

Silicon dioxide (SiO₂) and titanium dioxide (TiO₂) nanoparticles have been shown to enhance growth and mitigate the adverse effects of salinity stress in various crops. This study investigated the effects of SiO₂/TiO₂ nanocomposites (NCs) on tomato plants (Solanum lycopersicum) under both normal and salt-stress conditions. For this purpose, tomato plants were irrigated with 0, 60, or 120 mM NaCl solutions for 30 days. Fifteen days after initiating the salt treatment, SiO₂/TiO₂ NC suspensions at concentrations of 0, 50, 100, and 500 mg/L were applied via foliar spray. The results showed that, under non-saline conditions, foliar application of SiO₂/TiO₂ NCs significantly increased the number of leaves, shoot dry weight, total chlorophyll, carotenoid content, soluble sugars, anthocyanins, and total phenolic content in tomato plants. Under saline conditions, the positive effects of SiO₂/TiO₂ NCs varied depending on the NaCl concentration in the soil. In plants exposed to 60 mM NaCl, SiO₂/TiO₂ NCs improved shoot fresh weight, total chlorophyll content, proline and soluble sugar levels, catalase activity and reduced H₂O₂ content, as well as increased total phenolic and anthocyanin content. These findings suggest that the SiO₂/TiO₂ NC application increases biomass production and improves the salt tolerance of tomato plants. Therefore, these nanomaterials could be a promising option for promoting tomato growth in slightly and moderately saline soils.