Developing Seed Technologies
• USDA Forest Service National Seed Lab
– Bob Karrfalt - Director
– Victor Vankus – Botanist
• Seed Cleaning – reported on last year
• Germination protocols and storage
– Protocols on ten species
– Germination protocols now allow for the start of seed
storage studies
• Sagebrush started
• Initiate forbs this coming year
– Could use assistance with more seed samples (4000
seeds/ lot)
Application of Seed Technologies
• Development of standardized testing rules to
determine value of seeds for buying and selling,
and for sowing
– Anticipate submitting AOSA rule proposals in 2011
• Defining the seed ecology:
– What are the conditions for germination ?
• How broad? How narrow?
• How might they vary with genetic source?
– When can we sow the seed? Cool or warm
germinator?
– A prerequisite for working with any species
8
ig
h
t
16
of
L
100
97 88 87
80
71 65
60
40 90 92 89 90
73
45
20
0
5 10 15 20 25 2030
Temperature
Hr
s
% Germination
Agoseris glauca germination
Agoseris glauca germination
• Germinates at any temperature from 3 to
20o C
– When chilled at 3o C, all germination occurred
in chill
– When not chilled, high germination occurred
at all temperatures from 5 to 20o C
• Need to sow while temperatures are < 20o
• Light seems to have no effect
16
2
4
3
t
0
8
0
5
1
10
6
15
2
20
Temperature
3
25
3
2030
ig
h
0
of
L
100
80
60
40
20
0
Hr
s
% Germination
Sphaeralcea coccinea
germination - no chill, no clip
16
2
3
0
t
0
8
0
5
2
10
3
15
2
20
Temperature
2
2
25 2030
ig
h
0
of
L
100
80
60
40
20
0
Hr
s
%
Germination
Sphaeralcea coccinea
germination - 28 day chill, no
clip
2
1
5
3
6
3
2
8
3
0
5
10 15 20 25 2030
Temperature
t
5
0
ig
h
1
16
of
L
100
80
60
40
60
20
0
3
Hr
s
% Germination
Sphaeralcea coccinea
germination - clip + chill 28 days
8
ig
h
t
16
of
L
100
80
66
56
48
48 53
60
40
68
60
58
53
20 35 44
0
5 10 15 20 25 2030
Temperature
Hr
s
% Germination
Sphaeralcea coccinea
germination - no chill + clip
Sphaeralcea coccinea Germination
• No clip gives 0 to 3 % germination in all
germination conditions tried w/ or w/o chill.
• Clip first, chill second, germination almost all
occurs in chill (3o C) in the dark.
• Clip and no chill, germination occurs equally in
almost all conditions. Maybe slower in cooler
temperatures.
• Light seems to have little effect
• Need a way to safely break seed coats in mass
2
5
7
10
14
17
22
26
25
22
15
20
25
2030
Temperature
t
16
8
ig
h
3
1
16
of
L
100
80
60
40
20
0
Hr
s
% Germination
Erigonum umbellatum
germination - no chill
8
ig
h
t
16
of
L
100
80
60
33 39 33
14 16
40
20
35 37 34 32 34
0 14
5 10 15 20 25 2030
Temperature
Hr
s
% Germination
Erigonum umbellatum
germination - 28 day chill
Erigonum umbellatum Germination
• Requires chilling
• Appears to germinate equally well at any
temperature from constant 10 to
alternating 20/30
• Need to test longer chill periods
Penstemon germination
• Penstemon accuminata 28 day chill: 0 to
2% germination in all conditions
• Penstemon dustus 28 day chill: 0 to 2%
germination in all conditions
• Penstemon speciosus 28 day chill: 0 to
2% germination in all conditions
• Tests will continue with longer chill periods
Using Equilibrium Relative Humidity
(ERH) as a Guide in Storing Native
Plant Seeds
(Water Activity is another term that is used for ERH)
Bob Karrfalt, Director, USDA Forest Service National
Seed Laboratory (rkarrfalt@fs.fed.us)
Humid air (70%)
Water
moves
both ways
or not at
all.
Moist Seed
The condition of a high equilibrium relative humidity. At
equilibrium this seed will measure an ERH of 70%.
Dry air (30% relative humidity)
Water
moves
both ways
or not at
all.
Dry Seed
The condition of a low equilibrium relative humidity. At
equilibrium this seed will measure an ERH of 30%.
Hygrometer measuring ERH of seeds in a covered box
Probe
Sample holder
A water activity (Aw)
meter used to measure ERH.
Meter
Water
Activity
Meter
Moisture Content vs Equilibrium Relative
Humidity
Green Ash (Fraxinus pennsylvanica)
35.00
30.00
y = 85.294x 3 - 99.113x 2 + 43.567x
R2 = 0.9779
Seed Moisture Content
25.00
20.00
15.00
10.00
5.00
0.00
0
0.1
0.2
0.3
0.4
0.5
0.6
Equilibrium Relative Hum idity
0.7
0.8
0.9
1
Wyoming Big Sagebrush Isotherm
Artemisia tridentata ssp wyomingensis
16
y = -2E-05x 3 + 0.006x 2 - 0.2913x + 10.65
R2 = 0.9636
Moisture Content %
14
12
10
8
6
4
2
0
10
20
30
40
50
ERH %
60
70
80
Key points of ERH
Can be used on any seed lot regardless of
Viability
Purity
Stage of extraction
Species
No conversion charts needed
Traceable standards available for calibration
Non destructive
Fast – Results obtained in a few minutes
Very easy to use
Low cost equipment ($200 to $2500)
Sagebrush Seed Storage Lot WP High Purity Seed
3 months
30
40
50
70
Blank
-20
-8
2
Storage Temperature C
20
%
70
60
50
40
30
20
10
0
ER
H
% Germination
Initial
germination
was 56%
Sagebrush Seed Storage Lot WP High Purity Seed
6 months
Initial
germination
was 56%
60
40
30
20
50
0
70
Blank
-20
-8
2
Storage Temperature C
20
%
40
ER
H
% Germination
80
Sagebrush Seed Storage Lot WP High Purity Seed
15 months
Initial
germination
was 56%
60
40
30
20
50
0
70
Blank
-20
-8
2
Storage Temperature C
20
%
40
ER
H
% Germination
80
Sagebrush Seed Storage Low Purity Lot CA2
6 months
100
50
30
40
60
70
Blank
0
-20
-8
2
Storage Temperature C
20
%
50
ER
H
Number of Seedlings per
Gram
Initial germination
was 48 seedlings
per gram
Sagebrush Seed Storage Low Purity Lot CA2
15 months
100
50
30
40
60
0
70
Blank
-20
-8
2
Storage Temperature C
20
%
50
ER
H
Number of Seedlings per
Gram
Initial
germination
was 48
seedlings
per gram.
Storage of Sagebrush in Sealed
Containers –Why?
• Genetic conservation via long term
(decades long) seed storage
• Have seed sources on hand for
emergency rehabilitation
• Preserve seed viability in multiyear
collections needed for common gardens
and other genetics work
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