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SEED GERMINATION AND SEEDLING
ESTABLISHMENT OF REDSTEM CEANOTHUS
M.
A. RADWAN, Pacific Northwest Forest and Range Experiment Station, USDA Forest Service, Olympia, Washington 98502
G. L. CROUCH, Pacific Northwest Forest and Range Experiment Station, USDA Forest Service, Olympia, Washington 985021
Abstract: Germination and seedling establishment of redstem ceanothus ( Ceanothus sanguineus Pursh)
were investigated. Seedcoat impermeability was overcome by heating with or without water, and embryo
dormancy was broken by stratification or potassium gibberellate (K-G&). The best results were obtained
by heating in water for 1 to 15 minutes at 90 C or 1 to 5 minutes at 100 C, followed by stratification for
4 months or soaking in 100- or 250-ppm K-GA3 solutions for 48 hours. Seedling production varied with
most factors studied. The greatest success was obtained after hot water treatment with or without appli­
cation of K-G&, sQwing in the fall, and with the use of protective screens. Improvement of percentage es­
tablishment with fall seeding and modification of K-GA3 treatment for spring sowing appear possible.
J, WILDL. MANAGE. 41(4):760-766
Redstem ceanothus, a deciduous shrub,
has a natural range extending from southern
British Columbia to northern California and
eastward to Montana (Hickey and Leege
1970:2). It is also found in the central Great
Lakes region (van Dersal 1938:90). Red­
stem is recognized as an important species
for wildlife food and shelter, watershed pro­
tection, and erosion control (Hickey and
Leege 1970, Reed 1974:285). In addition,
the plant is probably capable of improving
soil through nitrogen fixation like other spe­
cies of Ceanothus (Delwiche et al. 1965:
1046).
Seeds of redstem are dOlmant at harvest
and require scarification followed by sh'ati­
fication to break dOlmancy. Available in­
fOlmation on pregelmination h'eatments is
inadequate. In addition, there is no infor­
mation on the use of growth regulators as
substitutes for stratification, or on seedling
production under field conditions.
The purpose of this study was to deter­
mine the best laboratory methods for red­
stem germination. We applied heat, with
and without water, to overcome seedcoat
impermeability, and used stratification and
1 Present address: Rocky Mountain Forest and
Range Experiment Station, USDA Forest Service,
Fort Collins, Colorado 80521.
760
potassium gibberellate (K-GAg) to break
emblYo dormancy. We also conducted tests
in the field at 2 different sites in Oregon.
MATERIALS AND METHODS
The Seeds
Seed collections were made by E. P.
Harshman, Willamette National Forest, dur­
ing August 1970 from an area east of Eu­
gene, Oregon. The seeds were cleaned by
floatation in water, dried at room tempera­
ture, packed in a plastic bag, and stored at
about 5 C until used in 1971 to 1973. There
were no changes in viability or dOlmancy
during storage as indicated by periodic tests.
Laboratory Experiments
Heat Treatments. When water was
used, seeds were submerged in distilled
water at 90 C for 1 to 30 minutes and at
100 C for 1 to 15 minutes, and cooled to
room temperature in cold water. The
drained seeds were stratified or h'eated
with K-GAg before germination. When wa­
ter was not employed, the seeds were placed
in dishes and heated in an oven at 90 C and
at 100 C for 10 minutes to 24 hours. The
seeds were cooled to room temperatm'e
and soaked in K-GAs solutions before ger­
mination.
-
J. Wildl. Manage. 41 (4): 1977
Purchased
by the
Forest
Service, U.S. Department of Agriculture, for Official Use.
ESTABLISHMENT OF REDSTEM CEANOTHUS
Stratificatio n.-Following the hot water
treatments, the seeds were soaked in dis­
tilled water for 48 hours at room tempera­
ture, drained of excess water, and placed in
a refrigerator at 2 to 5 C. Stratification pe­
riods varied from 0 to 4 months, and the
times at which stratification was begun
were scheduled so that all treatments were
completed the same day.
Chemical Treatments.-Potassium gib­
berellate was tested as a substitute for strat­
ification on selected hot water treated seeds
and on all seeds heated in the oven. The
solutions ranged from 0- to 500-ppm K-GAa,
and the seeds were soaked in the solutions
for 24 or 48 hours before germination.
Germination.-There were 3 completely
random factorial germination experiments,
each involving seeds from 1 of the 3 various
treahnent combinations, hot water plus
stratification, hot water plus K-GAa, and
oven heat plus K-GA3• Three replicates of
50 seeds each were used for every treatment.
The seeds were placed to germinate on
moist filter paper in petri dishes. The dishes
were randomly placed in an incubator pro­
grammed for alternating diurnal tempera­
tures of 30 C for 10 hours and 20 C for 14
hours, with light available during the
higher temperature. Emergence of the radi­
cle was used as the criterion for germina­
tion, and germinants were counted at
weekly intervals for 4 weeks.
Germination percentages were calcu­
lated. All final cumulative germination data
of each experiment were subjected to an
analysis of variance after arcsine transfor­
mation, and means were compared accord­
ing to Tukey's test (Snedecor 1961:251).
Field Tests
Study Areas.-Two sites in the Oregon
Coast Ranges were selected. One site, in
the Corvallis watershed, has basalt-derived
soil, and the other, near Harlan, has sedi-
J. Wildl. Manage. 41 (4) : 1977
•
Radwan and Crouch
761
mentary soil. Both had been clearcut and
broadcast-burned within a year of seeding.
Both treated and untreated seeds were
tested.
Spot Seeding.-This test was designed to
compare seedling production after 3 differ­
ent pregermination treatments, when seeds
were spotted: (1) in each of 2 seasons,
(2) at each of the 2 clearcut sites, (3)
with and without protection with wire
screens, and (4) on each of 3 different
soil surface conditions. At each site, 48
seed spots were selected on each seed bed
type. The spots, 10 cm in diameter and 30
cm apart, were individually numbered and
marked with wire pins; and each h'eatment
combination was assigned to 4 spots at ran­
dom. In November 1971 and Aplil 1972,
seeds were surface sown at 50 per spot, and
screens were immediately installed after
sowing where specified. Seedlings were
counted periodically and recorded as per­
cents of seeds sown. The data were sub­
jected to analysis of variance after arcsine
transformation, and the means were com­
pared according to Tukey's test.
Broadcast Seeding .-One year after in­
stallation of the seed spotting experiment,
broadcast seeding was used to compare 2
pregermination treatments (hot water, and
hot water plus K-GAa); conh'ol seeds were
not included because their seedling pro­
duction had been virtually nil in the spot­
ting trial. Treated seeds were sown in the
fall and early spring at both locations,
within 2 km of the seed spot test. At each
location, 16 plots, 0.01 ha each and spaced
3 m apart, were established on uniform ter­
rain; and each time-treatment combination
was randomly assigned to 4 plots. Seeds
were broadcast at 1,000 per plot. Peliodi­
cally, the seedlings present were counted on
O.OO1-ha sampling transects established in
the center of each plot. The counts were
converted to seedlings per hectare, and
ESTABLISHMENT OF REDSTEM CEANOTHUS
762
Table
1.
Effects of heating In water and stratification
on
percentage germination of redstem ceanothus seeds.
Minutes of
heating
Months of stratification"
2
3
4
Average"
45
55
41
32
38
25
39 x
70
85
72
75
77
61
73 y
89
97
92
85
77
63
84 z
44ab
50a
44 ab
40b
39 be
31 e
64
84
83
74
45
70 y
97
93
92
75
41
80 z
41a
43 a
43a
37b
22 e
0
Heating in water at 90 C
1
2
5
15
20
30
Averageb
0
0
0
0
0
0
Ov
17
11
13
7
5
8
lOw
Heating in water at 100 C
1
2
5
10
15
Averageb
0
0
0
0
0
Ov
6
5
5
7
5
6w
37
31
37
31
19
31 x
a Seeds were heated in water before stratification. Ger­
mination percents are averages of 3 50-seed replicates,
and data were subjected to a complete analysis of variance.
b Within each of the 2 sections of the table, averages
followed by the same letter, a to c in a vertical sequence or
v to Z in horizontal sequence, are not significantly different
(P < 0.05) by Tukey's test.
treahuent comparisons were made using t
test (Snedecor 1961:45) as required.
RESULTS AND DISCUSSION
Laboratory Germination
Effects of H at Water and Stratification.­
All hot (90 C) and boiling (100 C) waters
tested were effective in permitting water
absorption by the otherwise impermeable
seeds, but no germination occurred without
stratification (Table 1). With both temper­
atures, germination of the imbibed seeds be­
gan after 1 month of stratification, increased
steadily with further chilling, and reached
a maximum at an apparently optimal strati­
fication period of 4 months.
The response to stratification varied with
the heating period. Over all stratifications,
germination was significantly reduced (P <
0.05) by heating longer than 20 minutes at
90 C and 5 minutes at 100 C. After the opti-
•
Radwan and Crouch
mum 4-month stratification period, heating
for 1 to 15 minutes at 90 C and 1 to 5 min­
utes at 100 C produced the best results. A veraged over each of these ranges, genni­
nation percents were similar for the 2 tem­
peratures, and exceeded 90 percent. This is not consistent with available information
indicating much lower germination after
various hot water treatments and 3 or 4
months of chilling (Glazebrook 1941, Peter­
son 1953, Gratkowski 1973). The discrep­
ancy may be due to differences in the seeds
tested and methods used for hot water
treatment, stratification, and germination.
K-GAa as a Substitute for Stratification.­
Soaking seeds in K-GAa solutions following
hot water treatment, broke embryo dor­
mancy without stratification (Table 2).
Gelmination varied significantly (P < 0.05 )
with the water treatment, K-GAa concen­
tration, and soak time. Overall, the highest
germination percents were obtained by
heating in water for 10 minutes at 90 C or
for 2 or 5 minutes at 100 C, followed by
soaking for 48 hours in 100- or 250-ppm
K-GAg solutions. The average maximum
germination of about 90 percent was as high
as that obtained from fully stratified seeds.
In addition, the gelminants from chemically
treated seeds appeared to be normal and as
vigorous as those from stratified seeds. Po­
tassium gibberellate, therefore, completely
replaced the seeds' 4-month optimum chill­
ing requirement without any detectable
harmful effects.
Efficacy of Dry Heating Plus K-GAa.­
Heat applied to dry seeds was effective in
overcoming seedcoat impelmeability (Ta­
ble 3). Germination following treatment
with K-GAa varied significantly (P < 0.05)
among and within the 2 temperatures tested.
Maximum percentages of germination were
obtained by heating for 8 to 16 hours at 90
C, and for
to 12 hours at 100 C. Outside
these optimum ranges, germinations were
J. Wildl. Manage. 41 (4) : 1977
ESTABLISHi\-IENT OF REDSTEM C EANOTHUS
Table 2.
•
Radwan and Crouch
763
Germination percentages of redstem ceanothus seeds after heating In water plus soaking In potassium glbberellate
(K-GA3) solutions.
K-GAa concentrations and soak periodsn
Minutes of
heating
50 ppm
24 h1'
48 h1'
100 ppm
48 h1'
24 hr
28
46
58
44
74
250 ppm
24 h..
48 hr
Avel'ageh
Heating in water at 90 C
2
5
10
Averageb
e
70
78
86
78 b
64
78
68
70 e
86
85
66
79b
44
42
53d
86
82
86
85a
46
66
72
61 e
84
82
92
86a
59x
66 Y
78 z
94
90
74
86ab
76
80
76
77be
94
94
74
87a
82x
85x
72 y
Heating in water at 100C
2
5
10
Averageb
76
84
76
79b
Seeds were heated in water before soaking in K-GA:l solutions. Germination percents are averages of 3 50-seed
replicates, and data were subjected to a cOluplete analysis of variance.
Within
each of the 2 sections of the table, averages followed by the same letter, x to y or Z in a vertical sequence
b
or a to e in a horizontal sequence, are not significantly different (P < 0.05) by Tukey's test.
U
consistently low; the lowest values occurred
after heating for
hour at 90 C and for
24 hours at 100 C. Heat became lethal only
when the treatment exceeded 16 hours at
90 C and 12 hours at 100 C. Dry redstem
seeds, therefore, can withstand much longer
periods of heating at high temperatures
than has been reported previously (Grat­
kowski 1973).
Averaged over each of the 2 optimum
Table 3.
Influence of oven heating plus soaking in potas­
sium gibberellate solution on percentage germination of red­
stem ceanothus seeds.
Hours of
heating
%
lh
2
8
10
12
14
16
24
Oven temperaturell
90 C
100 C
7 db
17 e
35b
59a
55a
60a
59a
51a
12 cd
31bb
75a
81a
79a
68a
73a
32b
32b
Ie
Seeds were heated in oven before soaking in laO-ppm
K-GA3 solution. Germination percents are averages of 3
50-seed replicates.
b Within each column, values followed by the same let­
ter are not significantly different (P < 0.05) by Tukey's
test.
•
J. Wildl. Manage. 4 1 (4) : 1977
ranges of heating periods, germinations
were 57 percent at 90 C and 75 percent at
100 C. Heating at 100 C, therefore, was
much more effective in overcoming seed­
coat impermeability than heating at 90 C.
However, the best germination possible
from seed heated in the oven was still lower
than the maxima obtained from seed receiv­
ing hot water treatments (Table 1 and 2).
In addition, heating periods required for
maximum gennination were consistently
longer with dry heat than with hot water at
the same temperature. The superiority of
hot water was probably due to the unusu­
ally high specific heat of water and to a
lack of desiccation of wet seeds during heat­
ing. The possibility that water eliminated
a germination inhibitor is unlikely, however,
since our unpublished data show that hot
water leachates from redstem did not inhibit
germination of radish or wheat seeds. Seedling Production
Spot Seeding.-Only 3 and 8 seedlings
were produced, respectively, from all seeds
spotted in the spring and from untreated,
fall-sown seeds. Impelmeability of the seed-
764
Table
E STABLISHMENT OF REDSTEM CEANOTHUS
4.
Redstem
ceanothus seedlings as
•
Radwan and C1'Ouch
percentages of seeds spotted In
November
1971
on 2 different clearcuts in
Oregon.-
Inspection dates
Category
Seed treatment: l>
Hot water + K-GA.
Hot water
Clearcut location:
Corvallis
Harlan
Seed protection:
Caged spots
Uncaged spots
Seed bed:
Charred duff
Burned soil
Unburned soil
April
1972
May
1972
June
1972
November
1972
May
1973
20a
17a
13a
10a
13a
9b
6a
6a
5a
5a
21 a
16a
16a
8b
15a
7b
9a
3b
8a
3b
28a
8b
19a
4b
17a
4b
lla
2b
9a
Ib
29a
16b
9c
18a
12a
5b
17 a
12 a
4b
8a
8a
2b
7a
7a
2b
II
Categories are main effects of a 4-way analysis of variance, and l11eans within categories and inspection dates followed
by the same letter are not significantly different (P < 0.05) by Tukey's test. Values of seed bed category are means from
32 seed spots and those of each of the remaining categories are from 48 seed spots.
b Seeds soaked in water at 90 C for 10 minutes with or without an additional soak in 250-ppm K-GA3 solution.
coats of untreated seeds prevented water
imbibition and the subsequent natural strat­
ification required for germination. Likewise,
lack of germination was probably respon­
sible for the failure of spring-sown, treated
seeds. Seedings in the spring did not pro­
vide hot water-treated seeds with sufficient
chilling to break embryo dormancy. Also,
under these conditions, leaching and deg­
radation of K-GA3 was probably sufficiently
fast that seeds had reverted to the dormant
state by the time conditions became favor­
able for germination. Concern over loss of
gibberellic acid from treated seeds of an­
other species has been discussed in another
paper ( Nord et al. 1971).
The remaining data from the spotting
test (Table 4) show that seedling emer­
gence at both sites began in April, and the
largest number was recorded on the first
inspection. Emergence continued through
June, but new additions were more than
offset by mortality of older seedlings. Mor­
tality continued through the year, and a
small percent of the seedlings produced re­
mained in the spots at the end of the study.
Seedlings emerged in similar numbers at
the 2 sites, but mortality was consistently
higher at Harlan; at the end, significantly
more (P < 0.05) seedlings remained at Cor­
vallis. Because seedlings were counted only
at relatively long intervals, it was not pos­
sible to identify accurately causes of mor­
tality. General observations, however, in­
dicated that losses were due to drought,
insects, and damping-off fungi.
The production, survival, and appearance
of the seedlings from the hot water and hot
water plus K-GA3 treatments were similar.
Evidently, seeds were not benefited by ap­
plication of K-GA3 due to possible losses of
the chemical as explained above. Embryo
dormancy of fall-sown, treated seeds, there­
fore, waS' probably broken solely by natural
stratification.
The most dramatic treatment effect re­
sulted from seed protection. Effects were
favorable throughout the study, and the
final number of seedlings was several times
greater in cages. The positive effect of cag­
ing was obviously due to the exclusion of
seed-eating mammals and birds, altl10ugh
J. Wildl. Manage. 41(4):1977
ESTABLISHMENT OF RJj;DSTEM CEANOTIWS
Table 5.
•
765
Radwan and Crouch
Performance of treated redstem ceanothus seeds broadcast on a clearcut In Oregon.
Inspection datesu
Seeding dates and
seed treatmentsll
May
1973
June
1973
October
1973
April
1974
April
1975
Seedlings per hectare
November 1972:
Hot water
Hot water + K-GA"
March 1973:
Hot water
Hot water + K-GA,
0
0
3,707 a
2,965 a
0
0
0
247
3,336
2,718
0
247
a
a
3,336
2,718
0
247
a
a
3,336
2,718
a
a
0
247
" Seeds soaked in water at 90 C for 10 minutes, with or without an additional 48-hour soak in 250-ppm K-GA3 solu­
tion.
b Plots sown at 100,000 seeds pel' hectare. Seedlings present are averages of 4 plots, and values within the same sow­
ing and inspection dates followed by the same letter are not significantly different (P < 0.05) by t test.
'
cages may also have improved the micro­
environment for germination and seedling
establishment.
The sUlface conditions of the seed beds
affected seedling production and survival.
Initially, more seedlings emerged on charred
duff than on either burned or unburned
soil, but early losses were also large on duff.
At the second inspection and until the end of
the study, the numbers of seedlings on the
2 burned seed beds were similar and sig­
nificantly greater (P < 0.05) than those on
the unburned plots. These differences sug­
gest that a more suitable seed bed environ­
ment occurs on burned than unburned soil.
Broadcast Seeding.-No test was ob­
tained at the Harlan site because the plots
were trampled by big game and cattle. The
data obtained at the Corvallis site (Table
5) showed that spling sowing was unsuc­
cessful as it was in the spotting test. No
seedlings were found on plots sown with
hot water-treated seeds, and final counts
from the other treatment averaged less than
3 seedlings pel' plot.
The results of the fall sowing test wel'e
much more favorable. Seedling emergence
began and peaked in late June. Some seed­
lings wel'e lost as the growing season pro­
gressed, bllt total losses were much lower
than with spotting (Table 4 and 5).. The
J.
Wildl.. Man,age. 41 (4)
:
1977
peak and subsequent seedling counts from
the hot water-treated seeds were higher
than those from the hot water plus K-GA3
treah11ent, but the differences were not sig­
nificant. Also, as in the spotting test, there
were no differences in appearance between
seedlings produced from both treatments.
In this test, the seeds broadcast in late
fall at the Corvallis site produced approxi­
mately 3,000 seedlings per hectare. This
seedling production rate was similar to that
obtained from unprotected seeds spotted
earlier at the same location.
CONCLUSIONS
Laboratory germination of innately dor­
mant redstem seeds can be promoted by
heating, followed by stratification or K-GA3
treahnents. Germination <l.nd establishment
of redstem in the field can be assured by
sowing heat-treated seeds in the fall. In
this study, only about 3 percent of seeds
broadcast or spotted without protection re­
sulted in established seedlings. However,
our results also suggest that percentage es.­
tablishment c n certainly be improved. Im­
pOltant means of improvement include site
preparation by scarification, drill seeding,
and chemical or mechanical seed protection.
Under some field conditions and for sow­
ing in the nursery to produce planting stock,
766
ESTABLISHMENT OF REDSTEM CEANOTHUS
spling sowing would be desirable. Such
plantings can be done after heating and
stratification treatments. A potential al­
ternative to stratification is the use of K-GA3
followed by the application of an adhesive
to minimize loss of the chemical. Such treat­
ment would require a much shorter time
than artificial stratification. Moreover, treat­
ment with K-GA3 alone should be useful
for quick evaluation of the germination po­
tential of different seed lots before sowing.
LITERATURE CITED
DELWICHE, C. C., P. J. ZINKE, AND C. M. JOHNSON.
1965. Nitrogen fixation by ceanothus. Plant
Physiol. 40(6): 1045-1047.
1941. Overcoming delayed
GLAZEBROOK, T. B.
germination in the seed of plants valuable for
erosion control and wildlife utilization. M.S.
Thesis. Univ. of Idaho, Moscow. 97pp.
H. 1973. Pregermination treat­
GRATKOWSKI,
ments for redstem ceanothus seeds. U.S. Dept.
Agric., For. Serv., Pac. N.W. For. Range Exp.
Stu. Res. Pap. PNW-156. lOpp.
HICKEY, W.O., AND T. A. LEEGE. 1970. Ecology
and management of redstem ceanothus-a re­
•
Radwan and Crouch
view. Idaho Fish & Game Dept. Wildl. Bull.
No. 4. 18pp.
NORD, E. C., L. E. GUNTER, AND S. A. GRAHA,\-!, JR.
1971. Gibberellic acid breaks dormancy and
hastens germination of creeping' sage. U.S.
Dept. Agric., For. Serv., Pac. S.W. For. Range
Exp. Stn. Res. Note PSW-259. 5pp.
PETERSON, R. A. 1953. Comparative effect of
seed treatments upon seedling emergence in
seven browse species. Ecology 34(4): 778­
785.
1974. Ceallothlls L. Ceanothus.
REED, M. J.
Pages 284-290 in C. S. Schopmeyer, tech.
coord. Seeds of woody plants in the United
States. U.S. Dept. Agric. Handb. No. 450. U.S.
Government Printing Office, Washington,
D.C. 883pp.
SNEDECOR, G. W. 1961. Statistical methods ap­
plied to experiments in agriculture and biol­
ogy. 5th ed. Iowa State Univ. Press, Ames.
534pp.
1938. Native woody plants
VAN DERSAL, W. R.
of the United States, their erosion-control and
wildlife values. U.S. Dept. Agric., Misc. Pub!.
No. 303. U.S. Government Printing Office,
Washington, D.C. 362pp.
Received 26 May 1976.
Accepted 15 July 1977.
J. Wildl. Manage. 41 (4) : 1977