Germination of seed lots of Italian ryegrass (Lolium multiflorum Lam.) after exstended natural ageing in cool storage

Fifteen seed lots of Italian ryegrass cultivar RvP produced in 1976-1981 were stored at c. 5°C until 1999. Periodically samples were extracted and the final germination and germination rate were assessed. Controlled deterioration was used to assess vigour on a number of occasions. Most seed lots retained final germination above 50% even after 20 years storage. Germination rate generally declined with age but not at the same rate in all lots. There was initially no correlation of germination rate with final germination, but a significant positive relationship developed after about 10 years storage. Final germination after controlled deterioration (CD) was initially correlated with germination rate but when germination after CD was reduced to less than 50%, the germination rate was consistently low.