Accelerated Ageing Vigour Test
Accelerated Ageing (AA) was initially developed as a test
to estimate the longevity of seed in commercial storage (Delouche
and Baskin, 1973) and has been used to predict the life span
of a number of different species. The test has subsequently
been evaluated as an indicator of seed vigour in a wide range
of crop species and has been successfully related to field
emergence and stand establishment. Surveys of Seed Testing
Laboratories in North America have shown that the AA test
is one of the most frequently used vigour tests (TeKrony 1983).
Source: International Seed Testing Association, Handbook of
Vigour Test Methods, 3rd Edition 1995.
Since then this test has been accepted for addition into
the ISTA rules for seed testing and is one of two ISTA recommended
vigour tests. Accelerated Ageing is also a recommended Vigour
test of the Association of Official Seed Analysts, Seed Vigor
Testing Handbook, Contribution No. 32.
The Accelerated Ageing test subjects seed to conditions of
high moisture and humidity. These variables are known to cause
rapid seed deterioration. Seed lots with high vigour should
be able to withstand these stress conditions and deteriorate
at a slower rate than lots with poorer vigour.
After the ageing period, which may be different for different
crop species, the seed is planted in germination test conditions.
The result is reported as a percentage. The closer the AA
number is to the germination the better the vigour. Results
are expressed as a percentage normal germination after ageing
(vigorous seedlings).
Remember it is important to support all vigour tests with
a germination result. Adequate germination is the first requirement
in choosing seed lots.
Crop species that have had accelerated ageing research conducted
includes: Soybean, Brassica spp., Sunflower, Beans, Clovers/Alfalfa,
Corn, wheat, and grasses. Seed Check Technologies has recently
conducted its own in house research using the accelerated
ageing test on Barley. Results in many cases predicted a drop
in germination extremely accurately.
Seed Check Technologies Inc. has seed technologists who have
recent training in Conductivity testing from Dennis TeKrony
at the ISTA Vigour workshop in South Dakota June 2002.
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