1997 Ornamentals Research Report - AUrora - Auburn University

18
18
Sequential Pro-Shear
Applications Enhance
Offset Formation in Hosta
JAMES M. GARNER, GARY J. KEEVER, D. JOSEPH EAKES, AND
J. RAYMOND KESSLER
Hostas, herbaceous perennials in the lily family, are
conventionally propagated by crown division, but this method
yields relatively few plants per clump and is typically
accomplished only annually. Rapid increases in plant numbers
and the introduction of new cultivars are delayed due to slow
multiplication through annual division. Previous studies have
demonstrated that application of the synthetic cytokinin Pro-
Shear induces the outgrowth of rhizomic and axillary buds in
hosta, and offsets formed from Pro-Shear-induced buds can be
removed from the mother plant soon after elongation and
rooted under intermittent mist. These findings suggest that
Pro-Shear-stimulated offsets can provide an effective
alternative to conventional propagation methods. Growers
propagating hosta in this manner may wish to utilize hosta
stock plants as a source for Pro-Shear-stimulated offset
cuttings, and harvest cuttings repeatedly over a given season.
The objective of this study was to determine the effects of
multiple Pro-Shear applications and subsequent repeated
removal of Pro-Shear-induced offsets on offset yield from
hosta stock plants.
ALABAMA AGRICULTURAL EXPERIMENT STATION
ALABAMA AGRICULTURAL EXPERIMENT STATION
Table I. Offset Number at 30, 60, 90, and 120 Days
after
Initial Treatment (DAT) in Two Hosta Cultivarss
Treated
with 0-4 Applications of 3,000 ppm Pro-Shiear
intervals throughout the growing
season to provide greater numbers of
offsets than could otherwise be
obtained by crown division. A practical
DAT
30
60
90
120
0
3.7
4.9
1.2
0.0
I
4.5
3.6
1.4
0.0
'Francee'
2
-
5.9
3.5
0.0
3
-
-
6.0
1.0
4
-
-
-
5.6
0
0.0
0.0
0.0
0.0
'Francis Williams'
I 2 3
3.9
2.4 3.7
-
0.0 1.0
5.4
0.0 0. .0 1.0
4
-
-
5.2
system for the accelerated
multiplication of hosta could be of
benefit to growers by allowing them to
propagate hosta efficiently and
economically. A propagation system for
hosta which employs Pro-Shear
METHODS
Container-grown, single-eye (no offsets) plants of
hosta 'Francee' and 'Francis Williams' were treated with zero,
one, two, three, or four foliar applications of 3,000 parts per
million (ppm) Pro-Shear. Initially, 40 plants of each cultivar
received Pro-Shear treatment and 10 controls of each did not.
At 30-day intervals thereafter, offsets were removed from
each plant. The number of treated plants was then reduced by
10, and Pro-Shear was reapplied to the remaining plants,
resulting at 90 days after initial treatment (DAT) in a total of
five treatments. At 30, 60, 90, and 120 DAT, visible offset
count and a growth index were determined for each plant.
RESULTS
As in previous studies, Pro-Shear application
promoted formation of offsets in hosta. At 30 DAT, offset
counts were higher in treated plants of both cultivars
compared to untreated controls (Table 1). At 60 DAT, plants of
'Francis Williams' that had been retreated had higher offset
counts than controls or plants that received only one Pro-Shear
application. In 'Francee' at 60 DAT, sufficient offsets had
formed in controls such that offset counts in controls or plants
not retreated were similar to retreated plants. At 90 and 120
DAT, plants of both cultivars that were retreated following
offset removal had higher offset counts than controls or plants
not retreated.
Repeated Pro-Shear application was required to
achieve a continued response in offset production, but
removal of offsets prior to reapplication of Pro-Shear did not
appear to affect subsequent response to Pro-Shear. Total offset
yield increased with an increasing number of Pro-Shear
applications. Total yield of offsets with zero, one, two, three,
or four Pro-Shear applications was 9.8, 9.5, 13.9, 17.4, or 22
for 'Francee' and 0, 6.3, 8.6, 14, or 18.2 for 'Francis
Williams,' respectively. Compared to controls, there was a
124% increase in offset counts for plants of 'Francee' that
received Pro-Shear applications. With Pro-Shear applications,
'Francis Williams' averaged 18 total offsets per plant, while
no offsets formed in controls over the 120-day period.
This study indicates that hosta stock plants could be
treated with Pro-Shear at 30-day
application to stimulate the outgrowth
of offsets could facilitate rapid multiplication of cultivars that
do not readily form offsets. These findings are a significant
step in the development of such a system.