Munro’s globemallow:
exploring seed dormancy
Olga A. Kildisheva and Anthony S. Davis
Center for Forest Nursery and Seedling Research
Department of Forest Ecology and Biogeosciences
University of Idaho
Acknowledgements
Funding for this research was provided by:
- Great Basin Native Plant Selection and Increase Project
- University of Idaho Seed Grant Program
- Idaho Transportation Department
- University of Idaho Center for Nursery and Seedling Research
A special thanks to:
Kas Dumroese, Nancy Shaw, Matt Fisk, Erin Denney, James Kingery,
Cathy Ford, and the Davis lab group for help and guidance.
Sphaeralcea munroana
Munro’s Globemallow



Perennial forb
Forms short branched
caudex with multiple
unbranched stems
Produces red to orange
inflorescences
Sphaeralcea munroana
Munro’s Globemallow




Deserts, valleys and
foothills among
rabbitbrush and
sagebrush
Well adapted to degraded
soils
Highly drought tolerant
Important component of
the Great Basin
ecosystem
The Seed



Schizocarps of 10-12
mericarps forming a ring
Mericarps contain 1-2
seeds
Seeds about 1.5 mm long,
pubescent
Jim Cane
Jim Cane
Jim Cane
Possibilities & Challenges




High potential for establishment
on degrades sites
Increased need for restoration
Poor in/ex situ germination
Scarification and/or stratification
may be required for germination
Research Goals


1. Understand dormancy requirements of Munro’s
globemallow.
2. Develop pre-sowing methods to improve
germination.
Seed Dormancy Basics
Physical
seed impermeable to water, usually due to
specialized structure designed for this purpose
 Broken by scarification
Physiological
physiological inhibiting mechanism of germination
 Broken by warm and/or cold stratification, GA
application
1. GA₃ and Scarification Treatments
Table 1.1. Treatment Summary
Control
No treatment
Scarified
Pierced with a scalpel
(GA 24)
Gibberellic Acid Soak
(GA 48 )
Gibberellic Acid Soak
(SGA 24)
Piercing + Gibberellic Acid
(SGA 48)
Piercing + Gibberellic Acid
(SW 24)
Piercing + Water Soak
(SW 48)
Piercing + Water Soak
Non-pierced, 24 h soak in 100 ppm GA3
Non-pierced, 48 h soak in 100 ppm GA3
Pierced, 24 h soak in 100 ppm GA3
Pierced, 48 h soak in 100 ppm GA3
Pierced, 24 h soak in DI water
Pierced, 48 h soak in DI water
Methods
Seeds were placed in a
germination chamber at
alternating day/night
temperatures of 24 C (8 h)
and 17 C (16 h) (Sabo et al. 1979).
1. Analysis
Three variables of interest:
1. (GC) germination capacity: the cumulative
germination percentage
2. (HL) half life: required time for 50% of viable
seed to germinate (HL)
3. (LAG): the duration of time before germination
1. Hypotheses


H₁: Mechanical scarification would result in in higher
GC and lower HL and LAG.
H₂: GA ₃ would decrease the HL and LAG.
Treated seeds would germinate faster and more uniformly.
1. Results
Table 1.2. Treatment effects on the germination behavior of Sphaeralcea munroana at
the end of the 21-day observation period.
Treatment
Germination
Half Life (d)
Lag (d)
(%)
Control
15.90
2.71
0.09
Scarification
87.06*
0.71*
0.33
GA (24 h)
15.90
1.64*
0.43
GA (48 h)
15.08
0.85*
0.18
Scarification + GA (24 h)
88.12*
0.58*
0.60
Scarification + GA (48 h)
Scarification + H2O (24 h)
Scarification + H2O (48 h)
*p < 0.05
81.68 *
93.37 *
71.90 *
0.55*
1.47*
1.79
0.39
0.00*
0.33
1. Results
100
Control
Cumulative Germination (%)
90
80
GA₃ (24 h)
70
GA₃ (48 h)
60
Scarified
50
Scarified + H₂O
(24 h)
Scarified + H₂O
(48 h)
Scarified + GA₃
(24 h)
Scarified + GA₃
(48 h)
40
30
20
10
0
0
5
10
Time (days)
15
20
25
1. Summary


Mechanical scarification significantly improved
germination success (physical dormancy).
GA3 did not result in improvements in
germination behavior, which may indicate the
absence of additional dormancy mechanisms.
2. Scarification and Stratification Treatments
Table 2.1. Treatment Summary
Control
No treatment
Scarified
Pierced with a scalpel
Stratified
Stratified on moistened filter paper at 4.6 0.2 C, 6 wk
Scarified +
Stratified
Pierced with a scalpel and stratified on moistened filter paper at
4.6 0.2 C, 6 wk
2. Analysis
Three variables of interest:
1. (GC) germination capacity: the cumulative
germination percentage
2. (HL) half life: required time for 50 % of viable
seed to germinate (HL)
3. (R) rate: daily germination percentage
2. Hypotheses



H₁: physical dormancy :
Scarification would increase GC and R parameters,
while lowering HL.
H₂: physiological dormancy:
Stratification would increase GC and R parameters,
while lowering HL.
H₃: combination dormancy:
The combination of scarification and stratification
would increase GC and R parameters, while lowering
HL.
2. Results
Table 2.2. Treatment effects on the germination behavior of Sphaeralcea
munroana at the end of the 21-day observation period.
Treatment
Control
Germination
(%)
8.35
Half Life
(d)
8.06
Rate (%/d)
4.09
Scarification
35.29*
6.99
2.36
Stratification
7.21
3.34
1.15
Scarification + Stratification
44.12*
2.87
1.77
*p < 0.05
2. Results
Cumulative Germination (%)
50
45
q1
G (t ) =
40
q2 - t
1 + e
q3
Control
35
30
Scarified
25
Stratified
20
15
Scarified +
Stratified
10
5
0
0
5
10
15
Time (days)
20
25
2. Summary


Germination was significantly improved with both the
scarification (35 %) and the combined scarification
and stratification (44 %) treatments.
Lack of significant (p = 0.1816) improvement over
scarification alone in germination following the
combined scarification and stratification treatment
suggests the absence of physiological dormancy.
Seed Dormancy Conclusions


Our results indicate that physical dormancy is primarily
responsible for poor germination rates of S. munroana.
Additional factors such as storage conditions, seed
moisture, collection timing and environmental
conditions during seed set may play an important role in
dormancy development.
3. Non-traditional Scarification
Treatments
Table 3.1. Treatment Summary
Control
Burning
No treatment
Soaked in alcohol and burned with a
torch, 10 sec
Heating
Placed in oven at 85 C, 1 h
Burning &
Heating
Burned with a torch, 10 sec
Placed in oven at 85 C, 1 h
Rock Tumbling Tumbled with abrasive media, 72 h
Boiling Water
Submerged in water at 100 C, 10 sec
Analysis
Three variables of interest:
1. (GC) germination capacity: the cumulative
germination percentage
2. (HL) half life: required time for 50 % of viable
seed to germinate (HL)
3. (R) rate: daily germination percentage
3. Hypotheses
H₁: Scarification would result in a lower HL and
higher GC and R values.
H₂: Burning and tumbling most closely mimic natural
phenomenon and would result in the highest GC.
Treated seeds would germinate faster and more
uniformly, especially those subject to fire or tumbling.
3. Results
Table 3.2. Treatment effects on the germination behavior of Sphaeralcea munroana
at the end of the 21-day observation period.
Treatment
Germination (%)
Half Life (d)
Rate (germ / d)
Control
10.65
1.57
1.40
Boiling H2O
49.04*
8.20*
4.19*
Tumbling
20.32
2.10
2.34
Burning
17.03
1.97
2.04
Heating
10.65
4.42
2.09
Burning + Heating
4.17
4.23
1.17
*p < 0.05
Cumulative Germination (%)
3. Results
35
G (t ) =
30
q1
q2 - t
1 + e
25
q3
Control
20
Boiling
15
Tumbling
10
Burning
5
Heating
Burning + Heating
0
0
5
10
15
Time (days)
20
25
3. Summary



Submerging seed in boiling water yielded the
highest germination (GC).
Seeds subject to the boiling water treatment
should be observed for a longer period.
Further examination of boiling temperatures and
seed submergence duration has potential to
further improve the cumulative germination rates
achieved by this treatment.
Current and Future Research

Evaluating the effects of temperatures and drought
stress on post-germination survival and growth of
S. munroana.
Thank you!
Sources
Bewley, J.D., and Black, M. (1982). Physiology and Biochemistry of
Seeds in Relation to Germination. 2.Viability, Dormancy and
Environmental Control. (Berlin: Springer-Verlag).
Bewley, J.D., and Black, M. (1 994). Seeds: Physiology of
Development and Germination. (New York: Plenum Press).
Roth, T. E., Holechek J. L., and Hussain, M. Y. (1987). Germination
Response of Three Globemallow Species to Chemical Treatment.
Journal of Range Management, 40(2): 173-175.
Sabo, D. G., Johnson, G. V., Martin, W. C., and Aldon, E. F. (1979).
Germination Requirements of 19 Species of Arid Land Plants. USDA
Forest Serv. Rocky Mtn. Forest and Range Exp. Sta. Res. Pap. RM210.
SAS Institute Inc., SAS 9.1.3 Help and Documentation, Cary, NC: SAS
Institute Inc., 2000-2004.