102
The reduction in seed quality (Q) could be a measure of
field emergence, or a combination of germination before
and after accelerated aging, field emergence, and
electrolyte conductivity. For these purposes, the
specific measure of seed quality is unimportant. The
squared mean plant quality rating (S) divided by the
maximum quality rating squared would likely yield a more
representative curve than a cubic equation for seed
quality. Any infection, evidenced by symptoms and signs
of pathogens on the stems and pods, could lead to seed
infection and reduced seed quality. However, the higher
the disease severity, the better the chance that the
infection has reached the seed, hence the squared term
to describe this type of relationship. The maximum
quality reduction (P) would have to be determined
experimentally. By whatever means used to measure {Q},
be it
on
a
scale
of 0
to 25 or
in
percent
, {P} would
also
have
to
appear
in
the same
form. An
appropriate
value
for
{P>
could
be
100% of
the
scale used, with a
much delayed harvest. Under normal conditions, 20% of
the range of the {S} scale would be a reasonable value.
The seed quality reduction from infection by pathogens
would be difficult to separate from physiological
decline, and both may have to be included in equation 3.
A factor multipled by the number of days after the