Response of tomato to silicon dioxide nanoparticles under salinity: Impact on photosynthesis, antioxidant enzymes activity, stress biomarkers and osmoregulatory substances

Soil salinity imposes pronounced barriers on agricultural productivity by negatively affecting plant growth, morphological traits, and key physiological and biochemical processes. Nanotechnology holds transformative potential for sustainable agriculture by improving enabling precision farming and boosting crop productivity with minimal environmental impact. This study demonstrates the effectiveness of silicon dioxide nanoparticles (SiO 2 -NPs) in alleviating salt stress in tomato ( Solanum lycopersicum ) plants. We determined the effect of SiO 2 -NPs (50 ppm) on mitigating salt (50 mM) stress in S. lycopersicum by examining various growth attributes and metabolic indicators. The findings demonstrated that SiO 2 -NPs significantly enhanced S. lycopersicum resistance to salt stress. Under salt stress, S. lycopersicum plants showed decreases in net photosynthetic rate (33.41%), reducing sugar (11.67%), and protein content (37.21%), along with increases in total alkaloids (18.67%), proline content (16.21%), and the activities of superoxide dismutase (76.42%) and peroxidase (55.73%). The foliar application of SiO 2 -NPs significantly enhanced salinity tolerance in S. lycopersicum , as indicated by reductions of 24.15% in malondialdehyde and 29.31% in hydrogen peroxide levels, accompanied by increases of 32.47% in SPAD value, 17.13% in protein content, 16.54% in reducing sugar, and 13.44% in total carbohydrate content. Collectively, these findings highlight the promising role of SiO 2 -NPs in mitigating salt-induced damage in S. lycopersicum by enhancing antioxidant defense, stabilizing cellular structures, and improving key physiological and metabolic functions. This study provides valuable insights into the potential application of SiO 2 -NPs as an effective nanotechnological strategy for enhancing salinity tolerance and sustaining crop productivity under saline conditions. • Salt stress significantly reduced growth, photosynthesis, and protein content in tomato. • SiO 2 -NPs mitigated salt stress by improving antioxidant enzymes activity and proline metabolism. • SiO 2 -NPs enhanced the concentration of osmoregulatory substances under salt stress. • SiO 2 -NPs reduced ROS formation by decreasing the level of hydrogen peroxide.