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