Foliar Application of Equisetum arvense Extract Enhances Growth, Alleviates Lipid Peroxidation and Reduces Proline Accumulation in Tomato Plants Under Salt Stress

Salinity is a major abiotic stress that affects physiological and biochemical processes in plants, reducing the growth, yield, and quality of crops. This problem has been intensified with the reduction of the cultivated area. This study evaluated the response of hydroponically grown tomato plants under salt stress to foliar applications of <i>E. arvense</i> extracts. Macro- and micronutrients, as well as silicon and phenolic compounds, were extracted using magnetic stirring and water reflux methods, the latter being the most effective. To evaluate the efficacy of <i>E. arvense</i> extracts, spraying was applied at two different doses: EQ-R-1 (23.6 mg·L^-1 Si and 0.5 mM phenolic compounds) and EQ-R-2 (5.9 mg·L^-1 Si and 0.125 mM phenolic compounds). Foliar application of both extracts alleviated salinity effects by reducing sodium uptake. <i>E. arvense</i> extracts mitigated oxidative stress by a decrease in electrolyte leakage by 29% and malondialdehyde and H₂O₂ concentrations by 69% and 39%, respectively, for the extract with the lowest dose. In addition, EQ-R-2 was also more effective by reducing 51.5% proline accumulation. These findings showed the potential use of <i>E. arvense</i> extracts as biostimulants to enhance plant tolerance to salinity providing new perspectives in agricultural systems.