Influence of Hydro- and Halopriming on Seed Germination Traits and Early Metabolic Profiles at the Two-Leaf Stage in Common Bean (Phaseolus vulgaris L.)

Common bean (Phaseolus vulgaris L.) is a nutritionally important legume and a major dietary source of macro- and micronutrients for millions of people, particularly in developing regions. However, its early growth stages are highly vulnerable to abiotic and biotic stresses, often resulting in poor germination and seedling establishment. Seed priming emerges as a promising technique to combat these challenges. Therefore, this study investigated the effects of distilled water and calcium sulfate priming on germination performance and early metabolic responses in five common bean cultivars (RS 5, RS 6, PAN 148, Tygerberg, and DBS 830). Seeds were assessed for final germination percentage (FG%), mean germination time (MGT), germination speed (GS), mean daily germination (MDG), synchronization index (SI), and seedling vigor index (SVI). Significant variations (p < 0.05) were noted among cultivars and treatments. Calcium sulfate priming improved germination and seedling vigor in most cultivars, while RS 6 performed better under distilled water. Untargeted LC-MS-based metabolomic profiling revealed different treatment-specific metabolic responses. Multivariate analyses, including PCA and OPLS-DA, demonstrated clear cultivar-specific clustering of metabolic profiles under both hydropriming and halopriming treatments. Variable importance in projection (VIP) analysis further identified key discriminant metabolites associated with each priming treatment. Calcium sulfate priming highly affected metabolites such as leucine, rutin, S-adenosyl-L-methionine, kaempferol-3-O-rutinoside, and soyacerebroside I, while distilled water priming highly affected metabolites such as luteolin, uridine diphosphate glucose, and 1-palmitoyl-2-myristoyl-sn-glycero-3-phosphocholine. Correlation analysis revealed positive associations between key germination traits and metabolites such as leucine and S-adenosyl-L-methionine in calcium sulfate primed seeds. In distilled water primed seeds, metabolites such as 1-palmitoyl-2-myristoyl-sn-glycero-3-phosphocholine and PE (18:2/18:2) were negatively and positively correlated with germination performance, respectively. PCA biplots further illustrated the alignment between specific metabolites, seedling vigor, and priming treatments. These findings highlight the potential of seed priming to enhance germination and metabolic profiles in common bean. However, the benefits are dependent on both cultivars and priming agents, emphasizing the need for tailored, cultivar-specific priming protocols to maximize performance.