| Seed
Lot Characterization and Recipe Development |
Priming
protocols (temperature, aeration, moisture, timing) vary on a species,
cultivar, and seed lot basis. Each seed lot must be assessed
individually and the optimum priming recipe developed and tested before
processing can proceed. Even portions of the same lot stored under
different conditions for a length of time must be treated separately.
Potential pathology issues for each lot must also be evaluated. Lots
unsuitable for priming are identified and rejected.
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| Processing
Time |
The
time required for priming varies by crop species and seed lot and is
largely a function of germination time and lot quality. The range for
the total process is generally between 4 and 6 weeks. At least half of
this time is needed to characterize the individual seed lots and
determine the optimum priming protocol. The remaining time is needed for
processing.
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| Shelf
Life of Primed Seed |
Shelf
life is a complicated subject and is influenced by many factors. The
most important factors include:
- seed lot quality,
- crop
species,
- seed moisture content in storage,
- transportation and storage
conditions (especially temperature),
- the degree to which a lot has been
primed, and
- subsequent seed treatments (fungicides, film coating,
pelleting).
Assuming proper transportation and storage conditions and no other
complicating factors (such as coating), deterioration in seed lot
performance is rarely experienced during the growing season for which a
lot was primed (generally 4 months). In most cases (assuming the same
qualifiers listed above), lot performance is maintained for much longer.
As storage time increases, the risk of loss also increases. Most lots
are stable, but a percentage deteriorate rapidly. Not only is the
priming effect lost, but generally a significant percentage of the lot
dies. Screening methods to predict high risk lots are needed. The
results of research in this area are promising, but a usable method of
predicting deterioration is not yet available.
Kamterter recommends that seed only be primed for planting during the
immediate growing season (standard industry practice). Priming seed for
planting in subsequent years is discouraged. In cases where primed seed
must be held for extended periods, the seed should be retested before
planting to assess whether deterioration may have occurred. Long term
storage tests to date with canola have been very promising. (No
significant deterioration has been observed on seed lots after one
year.) It is reasonable to conclude at this point, that canola is not
unusual in its storage properties and will not require modified storage
practices beyond what is advised for all primed seeds.
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| Treating,
Coating and Pelleting Primed Seed |
Primed
seed is compatible with nearly all subsequent seed treatment, coating
and pelleting. However, the possibility does exist that the germination
characteristics may be influenced. In some cases, priming is performed
to improve the vigor of lots that would otherwise not tolerate the
stress of coating or pelleting. In other cases, primed seeds may be more
sensitive than unprimed seeds and experience deterioration. Combinations
must be tested after priming, on a case by case basis, before other
commercial treatments are performed.
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| Transport
and Storage Conditions |
Exposure
to high temperatures, even for brief periods, can induce rapid
deterioration of all seeds. The risk is slightly greater with primed
seeds. In storage and transport, it is important to maintain seeds that
have been enhanced under dry, cool conditions. Temperatures of less than
70° F are recommended. If available, constant temperature is desirable
(it is important to avoid fluctuations in temperature). Unfavorable
storage conditions may negatively influence shelf life. |
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