Effect of seed size on germination, seedling vigor, electrolyte leakage, and establishment of bird's-foot trefoil (Lotus corniculatus L.)

Seed viability, seedling vigor, and field establishment were measured on five seed sizes from five commercial, Certified seed lots of bird’s-foot trefoil (Lotus corniculatus L. ’Leo’). Viability as determined by percent germination at 20 °C varied among seed lots and among seed sizes, but a consistent relationship between viability and seed size was not observed. Similarly, speed of germination did not vary in response to seed size but did vary among lots. Within a seed lot, seedling length after 7 days growth varied in response to seed size; the larger seeds produced longer seedlings. However, this relationship was not observed among seed lots because seed lots with the highest average seed weight did not produce the longest seedlings. The seedling vigor ranking on the basis of electrolyte leakage differed if leakage was expressed relative to seed weight or the seed number. Leakage per 100 seeds was significantly and negatively correlated with percent germination, but not with seedling length or field establishment. On the other hand, leakage per gram of seed was significantly and negatively correlated with percent germination, seedling length, and field establishment. The larger seed sizes within a lot tended to have improved field establishment, so field establishment was highly correlated with seedling length (r = 0.76). Electrolyte leakage per gram of seed, and percentage germination were also significantly correlated with establishment (r = − 0.59 and 0.45, respectively). Germination potential and ability of the seedling to elongate rapidly are related to the field establishment of bird’s-foot trefoil. Germination potential was primarily influenced by the seed lot, whereas the ability to elongate was influenced by seed size (within a seed lot).