The purity test is analysis that determines the composition
of a seed lot. It is a test required by the Canada Seeds Act
to determine whether or not a lot makes a Canadian seed grade.
It is also useful information to the producer planting the
seeds. It can tell you if other crop kinds, fungal bodies
or weeds that you do not have or want in your area exist in
a seed lot. It will also tell you the number of these contaminants
so that you can keep from planting large quantities of them
with your crop. Many weed species can be extremely invasive
and difficult and expensive to control once established.
There are two main areas used in physical purity testing.
One is the percentage test. The other is the numbers by count
or search of a particular weight of seed.
The Percentage Test:
This test breaks the quantity analyzed down into these
Pure Seed, Other crops, Weed Seeds, Inert
matter, and ergot or sclerotia bodies. The results are
expressed as a percentage by weight. Different weights
are examined for different crop kinds with a goal of looking
at approximately 2500 seed units. This test is especially
important when planting really chaffy species or kinds
that are prone to be high in contaminating species. The
percentage pure seed in combination with the germination
test helps determine seeding rates.
Examination by Count (Purity):
This test is an examination of known quantity of a seed
lot for contaminants. Different weights are examined for
different crop kinds with a goal of looking at approximately
25, 000 seed units. Contaminants are retrieved and classified
into different categories including:
weeds, Primary noxious weeds, Secondary noxious weeds,
other weed seeds, other crop kinds, ergot and sclerotia
bodies and others as required.
Other tests offered include
Weed checks and Seed or Plant identifications.
Seed Check has on staff experts in physical purity testing
in the areas of grasses/forages, native seeds, Canola/Mustards,
cereals, pulses, and vegetables/flowers. They are constantly
training and upgrading to ensure accurate results.