Conducting germination tests

There are different ways to test seed viability, but germination testing is the most accurate method. It determines what proportion of seeds in an accession will germinate under favourable conditions, and produce seedlings judged as normal according to specific criteria for each species given by the International Seed Testing Association (ISTA). As you learned in module 2, measuring the viability of seeds requires you to count germinated, un-germinated and abnormal seedlings at various points over a period of days or weeks.

Seeds of different species have different requirements. While some seeds can germinate under a wide range of conditions, in other species, germination can only be achieved under perfect conditions.

If a seed does not germinate during a germination test, there could be various reasons for this. The failure to germinate could be because of some mechanism within the seed, or environmental factors outside it. The seed could be immature, dead or empty. By dissecting a seed that failed to germinate, you can tell which of these apply. Alternatively, the failure to germinate may be because the seed is quiescent. If the seed is quiescent, it may still be perfectly capable of germinating in a more suitable environment.

In the next activity, you will start to unpack what we mean by ‘a suitable environment’. Have a go at the poll, which asks you to rate different aspects of a seed’s surroundings, in terms of how important you think they are for germination. In reality, of course, the factors that influence germination are highly species-specific, but for the purpose of this poll, we encourage you to think about generalities.