Genomic insights into salt adaptation reveal antioxidant‐related candidate loci in barley

Abstract Repeated salinity exposure imposes cumulative ionic and oxidative stress that threatens both redox homeostasis and grain productivity in barley ( Hordeum vulgare L.), yet the genomic basis of lineage responses to recurrent salinity remains poorly understood. Here, we investigated recurrent‐stress priming in a diverse panel of 138 barley genotypes grown across three control cycles (C 1 –C 3 ) and three recurrent salt‐stress cycles (S 1 –S 3 ; 150 mM NaCl), integrating high‐throughput phenotyping, antioxidant profiling, 19K single‐nucleotide polymorphism genotyping, and genome‐wide association analysis. Yield‐related architectural traits showed strong cross‐environment conservation, consistent with stable phenotypic relationships. In contrast, antioxidant traits formed a tightly coordinated defense module that became progressively more negatively associated with yield under repeated salinity, revealing a context‐dependent relationship between protection and productivity. Multi‐environment genome‐wide association study yielded one false discovery rate‐supported association and 40 suggestive associations; recurrent suggestive regions included two loci on chromosome 2H associated with leaf ascorbate and grain weight and a locus on chromosome 7H at which the G allele class had higher glutathione than the A class. Together, these findings characterize recurrent‐stress lineage conditioning rather than transgenerational memory in unstressed descendants. The prioritized candidate regions provide hypotheses for fine‐mapping, functional validation, and marker‐assisted breeding for salinity resilience in barley.