Comparative Physiological and Biochemical Mechanisms of Salt Tolerance in Four Quinoa Cultivars Under Varying Salinity and Sodicity Levels

Salinization and sodication present significant threats to crop productivity in many parts of the world including Pakistan. Cultivating halophytes like quinoa presents a viable solution for the profitable use of salt-affected lands. This study specifically examines the performance and salt tolerance mechanism of four quinoa accessions under varying salinity and sodicity levels. In addition to a control group, different combinations of electrical conductivity and sodium adsorption ratio (ECe dS m⁻¹ SAR levels) were established: 10:20, 10:40, 20:20, and 20:40, achieved by using a mixture of salts. Most of the quinoa cultivars exhibited robust growth, with the exception of GLN-22, which proved unable to withstand high levels of salinity and sodicity, resulting in a 78% reduction in yield. GLN-29, on the other hand, demonstrated superior performance across all levels of salinity and sodicity. UAF-Q7 excelled under conditions of high salinity and low sodicity compared to equivalent salinity levels but elevated sodicity. Meanwhile, GLN-33 exhibited enhanced growth under elevated sodicity levels but struggled in the face of high salinity stress. In terms of nutrient uptake, GLN-29 displayed a higher accumulation of Na⁺ (32%) in older leaves compared to younger ones, alongside elevated levels of antioxidant activity at all salinity and sodicity levels. Notably, GLN-29 exhibited excellent adaptation to both high salinity and sodicity levels, resulting in the highest grain yield (14.75 g/pot) and the salt tolerance mechanism was associated with highly efficient K⁺ retention and transport of Na⁺ to older leaves. This underscores the necessity for further comprehensive field studies to ascertain its suitability for the sustainable utilization of salt-affected soils.