Fig. 3.

Lettuce seedling quality after storage under various conditions. Initially the seeds had been stored for 2, 3, 4 or 5 years under warehouse conditions (lots 2Y, 3Y, 4Y and 5Y). Subsequently the seeds were stored as indicated, in glass jars containing air at ambient pressure (0·1 MPa Air), in tanks filled with high-pressure nitrogen (18 MPa N₂), air (18 MPa Air) or oxygen (18 MPa O₂). Seedling quality was determined 10 d after the start of imbibition. Abnormal seedlings were divided over three categories: seedlings with necrotic spots on the cotyledons and growing roots, seedlings without root growth (with or without necrotic spots on the cotyledons) and seedlings where the radicle had protruded, but without further growth. Seeds showing no radicle protrusion were scored as non-germinated.