Context. Vicia sativa subsp. macrocarpa (V. macrocarpa), a large-seeded vetch, is underutilised and has been proposed as a putative source of seed feed along with V. sativa subsp. sativa (V. sativa, common vetch).

Aims. The study aimed to compare the two subspecies for a range of seed yield and quality traits.

Methods. Three accessions of each subspecies were grown under field conditions during two growing seasons. Measurements included pod and seed morphology, seed yield per plant, pod shattering and seed toughness, seed nutritional traits, and insect damage.

Key results. No significant differences were found for seed weight per plant (9.95–14.75 g); however, V. macrocarpa accessions showed lower emergence percentages (7–18%) and higher pod shattering (4.01% vs 0.17%) than V. sativa. The higher number of seeds per pod (8.50 vs 7.49) and larger seeds (70.63 vs 59.67 g) significantly contributed to yield of V. macrocarpa. Over the six accessions, seed weight per plant was significantly correlated with harvest index. The darker seeds of V. macrocarpa had lower seed protein concentration (25.96% vs 27.89%) and higher concentrations of antinutritional phenolic compounds (total phenols, total tannins, condensed tannins, flavonoids). Seeds of V. macrocarpa were enriched in manganese (17.72 vs 12.65 mg/kg) compared with V. sativa, but poorer in potassium (8.44 vs 10.50 g/kg). The high manganese and phenolics concentrations in seeds of V. macrocarpa were associated with lower percentages of bruchid-infected seeds and endoparasitoid (Triaspis thoracicus) damaged seeds, possibly due to toxic effects.

Conclusions. The two subspecies varied significantly in seed quality traits, but not yield.

Implications. More extensive comparisons between the two subspecies, with larger numbers of accessions, are needed in order to determine the potential of V. macrocarpa as a source of seed feed.