Germination, Growth, and Physiological Responses of 912 Faba Bean Accessions Under Saline–Alkali Stress

Saline–alkali stress significantly affects crop growth and yield, yet research on faba beans across vegetative and reproductive stages remains limited. We used a 124 mM mixed saline–alkali solution (pH 9.25) to test germination tolerance in 912 accessions, then grew 234 faba bean accessions with moderate saline–alkali tolerance at germination under substrate-based saline–alkali stress conditions (140 mM saline–alkali, pH 10.5) during the vegetative and reproductive stages. Under a 124 mM mixed saline–alkali solution, 912 faba bean accessions had an average germination rate (GR) of 49%. Stress significantly decreased the number of healthy seedlings (NHS); the average was only 33%. Accessions that performed relatively better under saline–alkali stress were the least common (18.31%), whereas those that performed relatively worse were the most common (39.58%). Faba bean accessions from China’s Shanxi Province (GR% and NHS% as high as 65.8% and 63.3%, respectively) and Africa showed better germination performance under saline–alkali stress. Autumn-sown accessions performed better than spring-sown accessions under saline–alkali stress (germination potential(GP), germination index (GI), GR and NHS: 44%, 3.22, 53% and 35% vs. 37%, 2.82, 47% and 31%, respectively). Accessions with red–purple and dark-green seed coats generally showed superior germination performance across most germination parameters. Accessions with wrinkled seed coats showed higher germination performance (the GP, GI, GR, and NHS were 47%, 3.08, 59%, and 35%) than those with smooth coats. Small-seeded accessions tended to perform slightly better under saline–alkali stress. Based on germination, seedling, and vegetative and reproductive stages assessments, H0001722 was identified as highly tolerant to saline–alkali stress, with 96.7% for each of GP, GR, and NHS, while Qingcan 19 was classified as extremely sensitive. H0001722’s MFV was twice that of Qingcan 19 through the vegetative and reproductive stages. This study provides valuable resources for identifying genes associated with saline–alkali tolerance and developing stress-resistant varieties.