Comprehensive evaluation of salt tolerance during the germination period of tomato germplasm and Screening of key indicators

This study aims to screen salt-tolerant germplasm resources during tomato germination and determine key evaluation indicators. First, 6 tomato germplasms were used, and 6 NaCl concentration gradients were set, 0.0% (CK), 0.2%, 0.4%, 0.6%, 0.8%, and 1.0%, and the optimal stress concentration was determined by radiculogenic length determination; then, 20 tomato germplasms were used as materials, and 8 indicators (germination rate, germination potential, germination index, vitality index, radiculogenic length, combyl length and fresh weight) were measured under the optimal concentration treatment. After calculating the salt tolerance coefficient, the correlation analysis, principal component analysis, membership function method and cluster analysis were comprehensively used for evaluation, and key indicators were screened through regression analysis. The results showed that: (1) NaCl stress showed a "low-promoting and high-inhibition" effect: 0.2%-0.4% treatment promoted the elongation of radiculogenic roots of most materials (except 20CL2045-0), with significant inhibition of 0.6%, and 0.8%-1.0% resulted in partial non-germination, and 0.6% was determined to be the optimal screening concentration; (2) The salt tolerance coefficients of each index were significantly correlated (P<0.05), and 2 principal components were extracted from principal component analysis (cumulative contribution rate 78.11%); (3) Cluster analysis divided the materials into highly salt-tolerant (2 parts), moderate salt-tolerant (15 parts) and sensitive (3 parts); (4) Regression analysis determined the germination index, radiculogenic length and fresh weight as key evaluation indicators. This study established a salt tolerance evaluation system for tomato germination period, screened out excellent germplasm and key indicators, providing an important basis for the study of salt tolerance mechanism and variety improvement.