Stability of Douglas-fir genotypes
across temperature and moisture
regimes: Implications for
breeding and climate change
Sally N. Aitken and Tongli Wang
Department of Forest Sciences
University of British Columbia
Breeding for stability
• Genotype-by-environment interaction complicates
selection and reduces genetic gain
• Breeders seek predictable genotypes with ‘stable’
performance across the range of potential
deployment environments within breeding zones
• Climate change (changes in temperature and
moisture regimes) will result in novel environments
What is stability?
Varying definitions
• Type 1: Genotype with small amongenvironment variance in phenotype (b<1.0)
• Type 2: Regression of performance against
site mean performance has average slope
(b1.0)
• Type 3: Deviation from regression mean
square as small as possible (high r2)
Genotype mean productivity
Types of stability
100
80
b=1
r2<1
60
b=1
r21
b=0
40
20
0
25
50
75
Site mean productivity
100
Objectives
• What environmental factors result in g x e?
• What are the growth and physiological
characteristics of stable genotypes?
• Can stable genotypes be selected from field
tests?
• How will select genotypes react to new climatic
conditions?
Selection of stable and
unstable parents
• 12-year stem volume data analyzed from 12
progeny test sites for 372 parents in 62 sixparent diallels
• 8 pairs of parents selected with similar breeding
values (>0) but contrasting contributions to
genotype-by-environment variance component for
diallel (Type 3 stability)
• Two or three full-sib families for each parent
included in experiment (total of 45 full-sib
families)
Ambient
10
Heated
5
05-Aug
16-Jul
25-Jun
09-Jun
22-May
08-May
20-Apr
25-Mar
Date
•soil moisture (well
watered and drought)
0.20
Water potential (mPa)
•Drought treatment had
minimum predawn water
potential of -1.2. mPa
15
0
•soil temperature
(ambient and warm)
•Temperature in warm
treatment 3 to 4oC above
ambient
20
02-Apr
• 4 treatments applied,
2 x 2 factorial with
25
Temperature (C)
• 1-year-old seedlings
planted into raised
nursery beds
0.00
-0.20
03-Jun
09-Jul
21-Jul
07-Aug
28-Aug
-0.40
Dry
-0.60
Wet
-0.80
-1.00
-1.20
Date
(mm)
Height
Treatment means
70
60
50
40
30
20
10
0
Total Height
1998 height
Cool Warm Cool Warm
dry
dry
wet
wet
Treatment
All treatments differ significantly
(Duncan’s multiple range test; p<0.05)
The progeny of stable and unstable parents
had different average norms of reaction
550
Stable parents
500
450
400
350
300
Average r 2 =0.713
250
550300
500
350
400
450
Unstable parents
450
400
350
300
250
300
Average r 2 =0.667
350
400
450
Treatment index (mm)
Stable and unstable families
differed significantly in their
response to treatments
500
450
400
350
300
Wet
W
250
A
Cool
Dry
D
H
Warm
Stable
He ight incre m e nt (m m )
He ight incre m e nt (m m )
500
450
400
350
300
Wet
W
250
A
Cool
Dry
D
H
Warm
Unstable
Analysis of Variance - F values for
treatments, stability and interactions
Trait
Ht 2
Soil
Soil
Stab.
temp moist. class
46.9* 220.6* 0.47
Temp x Moist.
stab.
X stab.
5.49* 0.03
Ht. Inc.
65.6* 294.8* 3.73*
3.71*
0.16
Dia. 2
14.0*
98.2*
3.41
3.71*
1.1
Dia. Inc. 19.7*
110.2*
4.6*
3.6*
1.41
0.01
2.73
0.08
123.3* 0.84
2.18
0.3
Root (g) 5.89* 6.9*
Shoot(g) 16.9*
Root weight
10
9
8
Stable
Unstable
7
6
CD
WD
CW
WW
Shoot weight (g)
35
30
25
Stable
20
Unstable
15
CD
WD
CW
Treatment
WW
• Fall cold hardiness
differed significantly
among moisture
treatments (p<0.05)
• There was no sig.
stability effect or
stability-by-treatment
interaction for cold
hardiness
Cold injury (%)
Cold hardiness and stability
70
60
50
40
30
20
10
0
Stable
Unstable
CD WD CW WW
Treatment
Selecting for stability in
Douglas-fir
• ‘Stable’ families selected
for Type 3 stability exhibit
type 2 stability
• ‘Unstable’ families selected
for Type 3 stability exhibit
both Type 3 instability
across all treatments and
Type 1 stability for
temperature
• Norms of reaction for
temperature appear to
vary more than those for
moisture
450
‘Unstable’
400
350
‘Stable’
300
CD
WD
CW
WW
Reaction norms for temperature
• The unstable parents
selected produce progeny
with higher mean growth
rates under poorer growth
450
conditions (lower
temperature and moisture)
400
• However, whether unstable
genotypes have Type 1
350
stability (consistent
performance) at higher
300
temperatures depends on
the norms of reaction to
temperatures above those
tested
Unstable
Cold
Low
test
temp.
Stable
High
Hot
test
temp.
Conclusions
• Douglas-fir families contributing to genotype-byenvironment interaction in field trials are less
responsive to soil temperature than stable families
but respond similarly to soil moisture
• Families with low Type 3 stability may be more
productive on poor field sites than families with
high Type 3 stability
• Deploying mixtures of genotypes with varying
norms of reaction to temperature may be an
appropriate strategy for uncertain future climates
• Further research is needed to characterize norms
of reaction to soil temperature over a broader
range
Acknowledgements
•
•
•
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Jack Woods, BC Ministry of Forests
Alvin Yanchuk, BC Ministry of Forests
Sonya Budge, UBC
Joanne Tuytel, UBC
Glen Reid, UBC
Corinne Stavness, UBC