Abstract
BACKGROUND: Silicon (Si) is a beneficial nutrient well-known for its functions in enhancing plant resistance to abiotic and biotic stresses. How Si application affects tomato yield and quality and underlying physiological mechanisms remain largely unclear. RESULTS: Our pot experiment showed that Si application (45 kg ha⁻¹ Na₂SiO₃) significantly promoted accumulation of nitrogen, phosphorus, potassium, and Si in the shoot of soil-cultured tomato in the greenhouse. Such improved mineral nutrition favored Si-applied plant performance in terms of plant height, stem diameter, single fruit weight, and yield, as indicated by significant increases of 11.34%, 53.57%, 62.12%, and 33.81%, respectively, when compared to the control (0 kg ha⁻¹ Na₂SiO₃). Higher catalase and superoxide dismutase activities in contrast to lower concentrations of hydrogen peroxide and malondialdehyde in the fruit suggested that Si application facilitated plant health. Importantly, Si upregulated expression of phytoene synthase and carotenoid isomerase and enhanced corresponding enzyme activities, resulting in higher lycopene concentrations in the fruit. Si also stimulated expression of vitamin C synthesis genes (GDP-D-mannose-3', 5'-isomerase, GDP-L-galactose phosphorylase, dehydroascorb-ate reductase, and monodehydroascorbate reductase) for higher levels of vitamin C accumulation. CONCLUSION: Si promoted tomato health, yield, and nutritional quality at the physiological and molecular level, favoring quality fruit production towards sustainable agricultural development.