Soil salinity is a critical abiotic stress that severely limits spinach (Spinacia oleracea L.) growth and productivity, particularly in salt-affected agricultural regions. Developing salt-tolerant cultivars and identifying genetically diverse germplasm are essential strategies to improve spinach resilience under saline conditions. In this study, 150 spinach accessions from the United States Department of Agriculture (USDA) germplasm collection are evaluated under control and salt stress (300 mM NaCl) conditions in a controlled greenhouse environment. The experiment was conducted using a randomized complete block design with three replications. Seedlings were assessed for chlorophyll content (SPAD value), leaf injury score (1–7 scale; 1 representing no visible injury and 7 representing completely necrotic leaves), and seedling height (cm). Substantial genetic variation was observed among the accessions. Five accessions were identified as salt-tolerant based on trait performance, including higher chlorophyll content, lower leaf injury scores, and greater seedling height under salt stress. These included CPPSIH 3 04, PI 171860, PI 177082, PI 171859, and PI 174387. Broad-sense heritability was high for chlorophyll content, leaf injury score, and seedling height, indicating that these traits are largely controlled by genetic factors under salinity stress. A negative correlation was detected between chlorophyll content and leaf injury score, suggesting that accessions maintaining higher chlorophyll content tended to exhibit less foliar damage under salt stress. These findings highlight valuable genetic resources for spinach breeding programs focused on improving salinity tolerance. Future studies will expand the evaluation to a broader collection of spinach accessions and implement genome-wide association studies (GWAS) to identify single nucleotide polymorphism (SNP) markers that can facilitate molecular breeding for salt tolerance.
