<p>Soil saline–alkalization is a major abiotic stress factor limiting crop productivity and yield. Evaluating and screening saline–alkali-tolerant tomato accessions are essential for improving tomato productivity and yield. Although salt stress has been extensively studied, the impacts of alkali stress, particularly on tomato plants, remain largely unexplored. This study investigated the physiological and morphological responses of 56 tomato germplasms under alkali stress conditions. Principal component analysis revealed that alkali stress tolerance in tomato germplasms was primarily determined by growth-related traits and photosynthetic parameters. A comprehensive ranking identified D47 as the most alkali-tolerant germplasm. Additionally, phenotypic evaluations confirmed that alkali-tolerant varieties exhibited better growth, ion homeostasis, and higher chlorophyll and carotenoid content than alkali-sensitive varieties. These findings provide insights into the genetic and physiological mechanisms of alkali tolerance in tomatoes and lay the foundation for future breeding programs to enhance crop resilience in alkaline soils. This study highlights the critical need for improved alkaline stress tolerance and presents a novel approach for identifying and utilizing alkali-tolerant tomato germplasm in agricultural breeding.</p>