Identification of Salt Tolerance and Stress Response in US Department of Agriculture Tomato Germplasm at the Seedling Stage

Soil salinity is a significant abiotic factor that impedes sustainable crop production in key agricultural regions worldwide. Saline cultivation adversely affects soil quality, whereas the use of saline water for irrigation disrupts the physiological and biochemical processes of plants. Continuous irrigation with high salt concentrations leads to a gradual buildup of soil salinity, thus hindering optimal plant growth and development. Consequently, there is a growing emphasis on breeding salinity-tolerant cultivars of various crops. In this study, 71 tomato accessions sourced from 20 countries and provided by the US Department of Agriculture were evaluated under controlled greenhouse conditions and subjected to saline stress (200 mM NaCl). The experiment used a split-plot design, with the salt treatment serving as the main plot and the tomato accession as the subplot, which were arranged in a completely randomized design with three replications. Results identified nine accessions (PI 109837, PI 127820, PI 270256, PI 634828, PI 636205, PI 636255, PI 647143, PI 647528, and PI 647556) as salt-tolerant. Additionally, high broad-sense heritability was observed for the leaf injury score and leaf chlorophyll content. Furthermore, positive correlations were found among parameters related to the leaf injury score and leaf chlorophyll content (soil plant analysis development value). These findings offer valuable insights for tomato breeding programs, particularly those focused on enhancing salt tolerance of elite cultivars of this crucial crop.