Alfalfa (Medicago sativa L.) is an important forage crop whose production capacity is strongly influenced by seed vigor, with higher vigor ensuring more stable and elevated yields. However, the traditional seed vigor detection methods are time-consuming, destructive, and difficult to apply on a large scale. In this study, shortwave infrared hyperspectral imaging (SWIR HSI), scanning electron microscopy (SEM), and synchrotron radiation Fourier transform infrared (SR FTIR) microspectroscopy were combined to achieve macro-micro evaluation of alfalfa seed vigor and elucidate the effects of different HVEF dosages. Physicochemical and spectral profiling demonstrated that alfalfa seeds exposed to an optimal HVEF treatment (1.6 kV/cm for 60 s) displayed spectral enhancements that precisely tracked with vigor metrics from conventional germination tests. For robust data interpretation, chemometric modeling utilizing MSC-PLSDA yielded the highest classification accuracy across distinct HVEF treatments, while an SG-SVR model delivered superior predictive performance for vigor traits, as confirmed by visualization mapping. To mechanistically underpin these macroscopic gains, micro-level structural and biochemical analyses were conducted. Scanning electron microscopy (SEM) demonstrated surface structural alterations indicative of enhanced seed coat hydrophilicity, while SR-FTIR microspectroscopy and spatial mapping confirmed a significant enrichment of hydrophilic biopolymers, specifically polysaccharides (1086 cm-¹), proteins (1650 and 1550 cm-¹), and cellulose (1420 cm-¹). This macro-to-micro methodological approach provides a rapid, non-destructive strategy for vigor evaluation and mechanistic analysis, and provides a meaningful technical reference for seed quality assessment of other crop seeds.

Paper Linkage：https://doi.org/10.1016/j.indcrop.2026.123606