Factors affecting the viable seed content of soils beneath lowland pastures.
The buried viable seed content was determined for some leys and permanent pastures. Seeds of Poa annua were abundant under the leys but absent under the permanent pastures. P. trivialis seeds were present in all the soils sampled, while seeds of Festuca rubra and Lolium perenne were rare or absent. In studies of innate dormancy of freshly-shed seeds, those of P. annua shed early in the season were innately dormant; burial or darkness enforced dormancy on a proportion of P. annua and P. trivialis seeds. Seeds of F. rubra and L. perenne had no innate dormancy and dormancy also could not be enforced. The assessment of buried viable seed content is interpreted in the context of the history of the swards and the management practices applied, and the presence or absence of dormancy mechanisms. All the results are related to the known sequence of changes in the botanical composition of lowland pastures after reseeding with L. perenne.