EVIDENCE FOR AN ENDOGENOUS CYCLE OF DORMANCY IN DRY STORED SEEDS OF POA TRIVIALIS L.

Publisher Website
Google Scholar
Abstract
Seeds of Poa trivialis L. (rough meadow-grass) were collected from two contrasting habitats during the summer of 1982. Collections from an arable population were obtained on three occasions and seeds from a grassland population were collected once. Although both populations responded similarly to various combinations of light, temperature and nitrate, the arable collections were markedly more dormant. Loss of dormancy of the grassland and early arable populations one month after collection was rapid in seeds stored at ambient temperatures and at 4.degree. C but more delayed in those stored at 23.degree. C. Despite a gradual loss of dormancy during storage, cyclic changes in dormancy were also evident, especially at 23.degree. C. The percentage germination of the various collections 7 d after incubation following storage at 23.degree. C increased over the first three months, but declined late following six and 12 months storage and increased again after 15 months storage. At 4.degree. C the arable collection lost dormancy more slowly than the other two collections and germination was greatest after six months storage; a reduction in percentage germination occurred after twelve months. Seeds buried at 5 and 15 cm showed cyclic changes of dormancy, being least dormant in autumn and spring, but most dormant in summer, corresponding to the natural periodicity of germination. It is proposed that cyclic changes in dormancy are regulated by endogenous rhythms and seasonal changes of temperature. The ecological implications of the germination behaviour of this species in various habitats are discussed.