Comprehensive Evaluation and Screening for Salt Tolerance Germplasms at Seedling Stage in Eggplant

Salt stress presents a major environmental constraint to global agricultural productivity and crop yield stability. Eggplant (Solanum melongena L.) is one of the most extensively cultivated Solanaceae crops worldwide, and the characterization of its germplasm for salt tolerance is essential to develop breeding programs to target its abiotic stress resilience. In this study, 200 mmol/L NaCl was identified as the initial screening concentration for the discrimination of salt tolerance levels in eggplant seedlings. Salt tolerance indices derived from 13 descriptors, including the plant height, stem diameter, and leaf number, were used to evaluate 165 germplasm resources (108 inbred lines and 57 commercial cultivars). These 165 germplasms were grouped into five groups, and six highly tolerant and eight highly sensitive germplasms were identified. Importantly, a stepwise multiple linear regression model incorporating the root surface area, leaf number, leaf water content, malondialdehyde content, and stem water content achieved 90.02% predictive accuracy, establishing a high-throughput screening protocol for germplasm selection. This systematic approach provides methodological advancements for precision breeding and identifies key physiological and morphological markers for salt tolerance improvement in eggplant.