The sowing
guidelines have undergone
revisions in 1996, 1999
and most recently in 2001.
Additional details on the
1999 (select Vol 3 #4) or
2001 (select Vol 5#2) can
be downloaded from the following
link:
http://www.for.gov.bc.ca/hti/publications/notes/notes.htm
Some nurseries
have asked to have their
nursery specific guidelines
entered as a default in
SPAR. This intuitively seems
reasonable, but it produces
problems when one is comparing
production figures across
nurseries. The same amount
of seed could be used to
produce different quantities
of seedlings at different
nurseries. The problems
become multiplied when one
considers the impacts of
changing nurseries on seedling
production.
Nursery
Grams Adjustment Screen
To assist
with nurseries wishing to
be efficient with seed a
new Nursery Grams Adjustment
Screen has been added
to SPAR (look on the Services
menu). Nurseries can now
select sowing requests based
on:
- Request Agency (Client)
- Species
- Stock type
- Container type
- Planting year/season
- Stock age
and bring
these up on one common screen
where gram quantity can
be adjusted. Previously
each sowing request would
need to be brought up individually
and changes entered, making
it a relatively slow process.
Minor adjustments
to the sowing guidelines
are being introduced for
2007 sowing. The change
is only for
lodgepole
pine (Pli) seedlots
and the reduction amounts
to a 6.3% to 8% decrease
in allocated seed depending
on seedlot germination capacity
(%). For seed owners this
means that these guidelines
suggest that they should
be able to obtain more trees.
For nurseries it means that
less seed will be provided
to produce Pli seed if they
have followed these guidelines
in the past. This change
is in response to the need
for improved seed efficiencies
with Pli due to various
challenges such as mountain
pine beetle, wildfires,
and the low inventory of
seed orchard seed.
The new Pli
guidelines and current guidelines
for other species are illustrated
in Figure
1 for GC values between
70 and 100% (covering most
Pli seedlots).
- The changes have been
realized by reducing
the correction or oversow
factor by 0.1.
- This factor is entered
to two decimal places
and allows for a streamlined
reduction in seeds per
seedling across the
germination range.
- The new 2007 Pli guidelines
do not provide specific
sowing factor or correction
factor terms as these
small reductions in
seed are best implemented
by each nursery with
consideration to their
sowing equipment and
attitude to risk.
To compare
seeds supplied per seedling,
at 99% and 100% GC the term
is reduced from 1.75 to
1.61 while at 69 and 70%
GG the seeds per seedling
goes from 4.81 to 4.43.
A comparison of the changes
in seeds per seedling for
GC values between 100 and
21% (the lowest GC value
in the guidelines) are illustrated
in Table
1. The seeds per seedling
number is important as it
the value used in the calculations
converting seeds to seedling
and vice versa. The equations
are the same as those presented
in 2001, but are repeated
here for ease of reference.
Figure
1. A comparison of seeds
per seedling supplied through
the 2007 Pli guidelines
and 2007 non-Pli guidelines
(=2001 guidelines) from
69 to 100% germination capacity.
Dave Kolotelo
- Susan Zedel - Al McDonald
Table
1. A comparison of the
seeds supplied per seedling
and % reduction of the 2007
Pli guidelines and 2007
guidelines for other species.
