Vernalization responses and subsequent fertility of two climatically distinct populations of rattail fescue (Vulpia myuros [L.] C.C. Gmel.).
Rattail fescue has become increasingly problematic in North America as a result of the greater adoption of no-till practices. While rattail fescue is described generally as a winter annual, there exists a wide variation in the life history documentation of the species. In some instances, rattail fescue has been observed behaving as a spring annual. In order to assess the vernalization plasticity of rattail fescue, laboratory-germinated seedlings from two climatically different rattail fescue populations, eastern versus western Oregon, were exposed to 4, 7 or 10°C temperatures for 0, 2, 4, 5, 6, 6.5, 7 or 8 weeks of vernalization. Following vernalization, the seedlings were transferred to a greenhouse and the developmental stages were recorded. After 13 weeks, the emergent inflorescences were clipped and the seeds were tested for germinability. The initiation of sexual development in the eastern population was affected significantly by the vernalization temperature and length, while the western population only responded to the vernalization length. In general, a faster progression through the reproductive stages of development was associated with longer vernalization lengths. Lastly, there was an increase in the germination rate of the seeds that were produced on the parent plants that were subjected to longer vernalization lengths, regardless of the population or vernalization temperature. The level of plasticity in the vernalization response between the two tested populations indicates that land managers should monitor local population life history traits in order to ensure that effective weed control is implemented at the correct growth stage.