| dc.description.abstract | The effective root growth potential (RGP) of both potted and
outplanted jack pine seedlings grown in Lannen-Sokeri FH-408 paperpots
and Can-Am #2 Multipots was measured on three test dates during the
summers of 1986 and 1987. Effective RGP refers to the potential of
outplanted container seedlings to extend new white roots into the
surrounding soil. In 1987 two crop types, overwinter and current crops,
were also compared. Effective RGP was measured in three zones: 1, the
upper half of the cylindrical area containing the container plug; 2, the
lower half of the same area; and 3, the bottom of the plug. The number
and length of white root tips projecting from the plug were counted and
measured to determine root number (RN) and total root elongation (TRE)
in cm from each zone for each container type. Seedlings grown in the
Can-Am #2 Multipot had a significantly higher effective RGP than
seedlings grown in the FH-408 Paperpot at all three test dates for both
data sets in 1986 and 1987. Effective RGP was highest from root zone 3
for seedlings grown in both container types. The overwinter crop also
had a higher effective RGP than the current crop seedlings. This
difference was significant only in the potting trial.
The morphological development of the three crops of seedlings used
in this study was also monitored. Seedling height, root collar diameter
and shoot and root dry weights were measured at two week intervals
throughout the greenhouse production phase. The Can-Am #2 Multipot stock
showed both superior morphological characteristics and regenerated far
more roots after outplanting than stock grown and outplanted in Japanese
Fh-408 Paperpots. The results of this study support the hypothesis that
seedlings grown in a container-free plug system such as the Can-Am #2
Mulitpot which are planted with an unrestricted rootball will exhibit a
higher level of root egress as expressed by higher effective RGP values
than those seedlings grown in the FH-408 Paperpot which are planted with
the paper barrier of the container still surrounding the rootball.
It is recommended that serious consideration be given to converting
from the use of restrictive containers like the FH-408 Paperpot to
container-free plugs for the production of forest tree seedlings. Some
recommendations for future research are also made. | |
