Getting difficult seeds to germinate

There is little point in conserving seeds unless they can be converted back into plants for use (e.g. in habitat restoration, re-introduction or research). Tackling seed collections that fail to germinate during routine germination monitoring is a major challenge for the Millennium Seed Bank Partnership (MSBP).

Seed surgery

Carefully removing a small portion of the seed coat often helps to overcome dormancy

Mature, healthy seeds that fail to germinate under favourable environmental conditions are said to be ‘dormant’. Seed dormancy has evolved in flowering plants so that seeds germinate at the correct time in nature, avoiding seasons when environmental conditions may be unsuitable for seedling establishment.

For example, in temperate regions the seeds of many plants are programmed to germinate only during the spring. After the seeds have been dispersed in the previous summer or autumn, they must experience the passage of winter before they are able to germinate. The period of chilling or cold stratification required to completely overcome dormancy often depends on where the plants come from. Seeds from regions with long winters usually require a longer period of chilling compared to seeds from milder areas. This is an example of ‘physiological dormancy’ because the block to germination resides in the embryo of the seed.

Another common type of dormancy is ‘physical dormancy’. In this case seeds are unable to germinate simply because they are enclosed by a hard impermeable seed coat which prevents the uptake of water. Water uptake or imbibition is the first crucial step towards germination in all seeds.

Although the conditions for seed germination can be extremely variable, plants that are related to each other or from the same habitat or climatic region often share similar requirements. MSBP scientists use this kind of information to predict the conditions needed for germination.

Long term climatic data for different locations can be found here:

http://news.bbc.co.uk/weather/hi/country_guides/
http://www.tutiempo.net/en/