Abstract
Abstract This study investigated the interactive effects of soil salinity (2.88 and 3.79 dS⋅m − 1 ) and foliar sodium selenate application (0.80 and 0.15 kg Se⋅ha⁻ 1 ) on the yield parameters and phytochemical composition of spinach ( Spinacia oleracea L. cv. Matador) under the conditions of semi-controlled pot trial under field conditions. The experiment confirmed that selenium biofortification is effective, increasing its levels in the plant ten-fold. Selenium has a positive effect, mitigating salt stress, and its uptake is closely linked to sulfur metabolism. Foliar application of selenium to spinach under salt stress conditions (up to 3.79 dS⋅m − 1 ) does not negatively impact yield, effectively increasing the content of bioactive components such as phenols and antioxidants. Studies confirm the synergistic effects of selenium and salinity, improving stress tolerance, mitigating sodium toxicity, and stimulating dry matter growth and S/Zn/Mn content. These findings demonstrate the viability of selenium foliar application for producing nutritionally enhanced spinach on salt-affected agricultural soils.