Influence of silicon and nano-silicon on salinity tolerance of cherry tomatoes (Solanum lycopersicum L.) at early growth stage

•Si alleviated the effect of salinity stress on the plant fresh weight, chlorophyll concentration, photosynthetic rate, and the leaf water content.•Silicon could protect photosynthesis activity of tomato plants against the hazardous effect of salinity.•There were no meaningful differences between the Si and N-Si applications.•Both forms of silicon were effective at lower levels in most measured characteristics

This study was conducted in a greenhouse using hydroponics system to study the ameliorating effects of varying levels of silicon (Si) and nano silicon (N-Si) on growth and some key gas exchange characteristics of tomatoes under salt stress condition. The experiment was arranged in a factorial design with 6 replications at NaCl levels of 0, 25, and 50 mM. The tested Si and N-Si concentrations were 0, 1, and 2 mM. After the Si and N-Si applications and NaCl additions to the nutrient solutions, plants were allowed to grow for 42 days. Plant growth and photosynthetic attributes as well as the water status of the plants were assessed. Results showed salinity had deleterious effects on the plant fresh and dry weights, root volume, and the stem diameters. Conversely, electrolyte leakage increased by increasing salinity levels. Increased salinity levels diminished sub stomatal CO2, photosynthetic rate, mesophyll conductance, and photosynthetic water use efficiency. The fresh and dry weights, root volume, and chlorophyll concentration increased with application of Si. Si alleviated the effect of salinity stress on the plant fresh weight, chlorophyll concentration, photosynthetic rate, and the leaf water content. Sub stomatal CO2 and stomatal conductance decreased with application of Si. Si and N-Si improved photosynthesis rate, mesophyll conductance, and plant water use efficiency under saline stress condition. No significant difference was found between application of nano size of Si and Si. Overall, application of Si was beneficial in improving the salt tolerance of the tomato plants.