Some definitions

In module 1, you learned some basic definitions of longevity and viability. Now let’s dive deeper into how scientists find out about these, and what they have learned. First, here are a few definitions of ways you can find out about a seed’s longevity and viability:

The time taken for viability to fall to 50%, p₅₀, is often used as a measure of seed lot longevity.

The length of time spent in a given storage environment is the storage period, p.

A germination test involves growing-out samples of seeds on wet paper or another medium such as agar, moist soil or sand.

The topographical tetrazolium staining test is a destructive test, which relies on the fact that viable tissue will react with the tetrazolium solution and therefore stain red, whereas non-viable tissue does not react.

In seed storage experiments to understand the relative longevity of different seed lots, seeds are subjected to high temperatures and humidity prior to testing germination. This can be used to assess seed lot vigor.