Germination of annual ryegrass seeds (Lolium rigidum Gaud.) as influenced by temperature, light, storage environment, and age

Germination of Lolium rigidum seeds, in the light (12 hr day length) and in the dark, at constant temperatures of 12, 18, and 24°C and an alternating temperature of 24/12° (12 / 12 hr), was studied in freshly harvested seeds and in seeds stored for 18 weeks. In freshly harvested seeds the highest germinability (80%) was recorded at 12° in either light or dark and at 24/12° in the light. After 18 weeks' storage, a germinability of between 95 and 100% was observed at 12° and 24/12° in the dark and at 24° and 24/12° in the light. In another experiment in which seeds from a different source were used, seeds kept in six different environments and recovered at 3-weekly intervals during a 21 week post-harvest period were examined for germinability and germination rate. The six environments were: storage in a room, storage in a 60/15°C temperature cabinet, and four field treatments in which seeds were buried 0.2 and 1.0 cm under both a bare and a mulched soil surface. Germination was tested in the light and in the dark at an alternating temperature of 24/12°. Major increases in seed germinability with age occurred during the first 9 weeks after harvest. The different environments influenced the relationship between seed age and germinability only during the first 9 weeks. Seeds located 0.2 cm beneath either a bare or a mulched soil surface during summer germinated at a faster rate than seeds kept in the other environments. These findings are discussed in relation to the germination behaviour of seeds in the field.