Salt Tolerance Evaluation of 15 Grape Germplasm and Screening of Salt-Tolerant Resources

Soil salinization severely restricts the sustainable development of the grape industry in arid/semi-arid northwest China. Establishing a standardized salt tolerance evaluation system and screening suitable germplasm are crucial. Fifteen grape germplasm (rootstocks, table/wine grapes, wild Vitis amurensis) were used to construct a salt stress screening system for tissue-cultured leafy single-bud stem segments. Tissue-cultured ‘Cabernet Sauvignon’ (main local cultivar) was treated with 0–100 mM NaCl; the half-inhibitory concentration (IC50 = 31.83 mM) was calculated using probit regression, and 50 mM NaCl (about 1.57 × IC50) was set as the screening concentration. Salt tolerance was evaluated by plant height, root length, rooting rate, survival rate, and salt damage index, with ranking/classification via membership function and principal component analysis. Na+/K+ contents in aboveground parts and roots of representative germplasm were determined by flame atomic absorption spectrophotometry. Significant differences (P < 0.05) in salt tolerance were observed, with germplasm classified into high/medium/low tolerance levels. Wild V. amurensis ‘Shuangyou’ showed the strongest salt tolerance: its roots accumulated 62.3% more Na+ than salt-sensitive ‘Cabernet Sauvignon’, while aboveground parts maintained stable K+ levels with a 3.8-fold higher K+/Na+ ratio. This study clarified grape germplasm salt tolerance potential, identified ‘Shuangyou’ as a high-quality salt-tolerant resource, and established a standardized screening system. The system enables rapid pre-screening of breeding materials, while ‘Shuangyou’ can serve as a donor parent for improving salt tolerance in grape breeding programs. This work provides theoretical and technical support for grape breeding and cultivation in saline-alkali soils.