The Agro-Physiological and Phytochemical Potential of Quinoa (Chenopodium quinoa Willd.) Under Saline Stress: A Comprehensive Investigation of Nutritional Properties and Antioxidant Activities

This study was conducted to evaluate the effects of varying irrigation salinity levels on the physiological and biochemical responses of Chilean white quinoa (<i>Chenopodium quinoa</i> Willd.) in two greenhouse cultivation seasons (2015 and 2016) in Cherfech, Tunisia. The experiment involved three treatments: T0 (control, using tap water with EC = 1.4 dS/m), T1 (EC = 9.0 dS/m), and T2 (EC = 18 dS/m). The results showed significant differences with multiple parameters. Quinoa irrigated with T2 exhibited superior growth and seed yield compared to the other treatments in both seasons. Additionally, soluble protein content increased significantly in the second season, especially in T2, while nitrogen content also rose notably from T0 to T2 in 2016. Bioactive compounds, such as vitamin C, phenols, flavonoids, DPPH, and ABTS, were highest in T2. Mineral content (K, P, Na, Mg, Zn, Ca, and Fe) showed considerable variation, with T2 generally presenting the highest levels. Amino acids exhibited notable changes, with an increase from T1 to T2, though lysine content decreased under T2 conditions. These findings indicate that quinoa can effectively adapt to saline irrigation, positioning it as a promising crop for cultivation in saline-affected regions.