Reaping what you sow - seeds and plant quality.

Germination problems in the nursery may lead to a reduction in the quality of the resulting plants and increase the length of the production cycle. Seed dormancy, handling and storage practices before sowing, date of sowing and moisture availability after sowing are probably the most important factors affecting seed germination in the nursery. The results of recent research have shown that dormancy can be broken more effectively in the seeds of many tree species using the target moisture content (TMC) method, which involves maintaining the moisture content (MC) of the seeds at a lower MC than the fully imbibed (FI) state (standard method) during chilling. The TMC seeds can be cold or freezer stored for more than a year with little effect on germination potential or reintroducing dormancy. Short periods of mild freezing or incubation at warm temperatures also may enhance germination in some species. Although the TMC method reduces the sensitivity of seeds to seedbed temperatures, it is preferable to schedule sowing operations to reflect the optimum temperature for germination in each species. Unlike the seeds of most other tree species, oak (Quercus robur L. and 0. pelraea L.) acorns are difficult to store, even over one winter. The results of recent research has revealed that soaking acorns for five days before storage at -3°C improved germination and the yield of usable plants in the nursery compared with acorns that were stored in the standard way. The type or combination of bed coverings used may also influence seedbed temperature and soil moisture availability. Seeds covered with sand followed by grit may germinate better than seeds covered with grit only (standard method for most small-seeded species in Ireland). The use of cloches or mulches may improve germination further. Seedbeds should be irrigated with frequent light (mist) applications (especially alder and birch seeds) of water during dry periods.