Use of silicon to protect tomato (Solanum lycopersicum L.) seedlings from low-calcium stress-derived oxidative damage

• Silicon reduces low-calcium-induced reactive oxygen species accumulation. • Silicon upregulates antioxidant defenses and osmotic regulation in tomato. • Silicon application mitigates plant growth inhibition under calcium deficiency. • Silicon alleviates low-Ca stress-induced damage in tomato roots and leaves. Given the environmental consequences of excessive chemical fertilizer use in agricultural production, it is imperative to identify alternative strategies to address nutrient deficiencies. Silicon plays a pivotal role in alleviating abiotic stress in plants and enhancing nutrient uptake; however, it remains unclear whether silicon can mitigate the effects of calcium deficiency in tomato seedlings. To address this issue, tomato seedlings cultured under low calcium conditions (0.1 mmol/L Ca 2+ ) were treated with silicon via direct application to the roots and leaves. The silicon treatment significantly reduced the superoxide anion content in tomato plants by 14.25 %–27.34 % and significantly increased the total polyphenol content by 2.9 %–13.5 % in all tomato organs under low-calcium stress conditions. Moreover, the application of silicon to the roots increased the tomato soluble sugar and protein content, and the application of silicon to the leaves significantly increased Superoxide dismutase activity. The application of silicon to both the leaves and roots alleviated the oxidative damage caused by calcium deficiency. These events were accompanied by activation of the ascorbic acid-glutathione pathway, osmotic regulators, and polyphenol accumulation. The results elucidate the effects of silica fertilization on tomato production, including its potential to mitigate the effects of low-calcium stress.