Performance under stress
Two men are walking on a
treadmill at a leisurely pace. Both men are using little
energy to keep up with the machine, and look refreshed.
Which man is in better athletic condition?
The answer is….there’s no real way to tell at the
pace they are going.
Speed up the treadmill and place some stress on the
athletes, and you should quickly see which man holds up
to the stress and is in better shape.
You can say the same for seed. Under ideal conditions
in the lab, with little or no stress, you may not be
able to see which seed lot is actually the strongest.
Comparing different seed lots under stress conditions,
like cool or hot or minimal moisture, or even too much
moisture will quickly separate the strongest seed lots
from the weaker seed lots. And by measuring the speed at
which the seed germinates under the stress conditions,
you can get an even clearer picture of the strongest or
most vigorous seed lots.
You get the
most vigor information when comparing seed lots under a
stress that makes germination difficult, but doesn’t
kill the seed. Here are a couple of tests that use
stress to separate the weak from the strong.
Accelerated Aging
Seeds are placed into a high humidity, high
temperature box for several days, stressing the seeds
before the actual germination test. After the aging
treatment, the seeds are planted to see which lot held
up the best against the damaging storage conditions.
Cold tests
Seeds are planted and placed into a cold
environment
for several days and then moved into a warmer condition.
Germination characteristics are measured to see how the
seed held up against the cold stress treatment.
Here’s a common test that relies mainly on speed of
growth to determine seed lot strength. The fastest
germinating and growing seed lot is said to be the most
vigorous.
Slant Test
Seed is placed on wet blotter paper in a box. The box
is set up at a slant so roots will grow straight down
toward the bottom of the box. Root length is measured.
The seed with the fastest growing root, is the seed with
the most vigor.
Keith
k.kubik@hmclause.com