Sally N. Aitken and Tongli Wang Department of Forest Sciences University of British Columbia
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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
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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. - PowerPoint PPT Presentation
Transcript of Sally N. Aitken and Tongli Wang Department of Forest Sciences University of British Columbia
Stability of Douglas-fir genotypes across temperature and moisture
regimes: Implications for breeding and climate change
Sally N. Aitken and Tongli WangDepartment of Forest SciencesUniversity 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 among-environment variance in phenotype (b<1.0)
• Type 2: Regression of performance against site mean performance has average slope (b1.0)
• Type 3: Deviation from regression mean square as small as possible (high r2)
Types of stability
0
20
40
60
80
100
25 50 75 100
Site mean productivity
Gen
otyp
e m
ean
prod
ucti
vity
b=1
b=0r21b=
1r2<1
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 six-parent 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)
-1.20
-1.00
-0.80
-0.60
-0.40
-0.20
0.00
0.20
03-Jun 09-Jul 21-Jul 07-Aug 28-Aug
Date
Wa
ter
po
ten
tia
l (m
Pa
)
Dry
Wet
0
5
10
15
20
25
25
-Ma
r
02
-Ap
r
20
-Ap
r
08
-Ma
y
22
-Ma
y
09
-Ju
n
25
-Ju
n
16
-Ju
l
05
-Au
g
Date
Te
mp
era
ture
(C
)
Ambient
Heated
• 1-year-old seedlings planted into raised nursery beds
• 4 treatments applied, 2 x 2 factorial with
•soil temperature (ambient and warm)
•soil moisture (well watered and drought)
•Temperature in warm treatment 3 to 4oC above ambient
•Drought treatment had minimum predawn water potential of -1.2. mPa
Treatment means
010
2030
4050
60
70H
eigh
t
(mm
)
Cool
dry
Warm
dry
Cool
wet
Warm
wet
Treatment
Total Height
1998 height
All treatments differ significantly (Duncan’s multiple range test; p<0.05)
250
300
350
400
450
500
550
300 350 400 450
Stable parents
Average r 2=0.713
250
300
350
400
450
500
550
300 350 400 450Treatment index (mm)
Unstable parents
Average r 2=0.667
The progeny of stable and unstable parents had different average norms of reaction1
99
8 h
eig
ht
incr
em
ent
(mm
)
Stable and unstable families differed significantly in their
response to treatments
AH
D
W
250
300
350
400
450
500
Heig
ht in
crem
ent (
mm
)
AH
D
W
250
300
350
400
450
500
Heig
ht in
crem
ent (
mm
)
Cool CoolWarm Warm
Wet Wet
DryDry
Stable Unstable
Analysis of Variance - F values for treatments, stability and interactions
Trait Soiltemp
Soilmoist.
Stab.class
Temp xstab.
Moist.X stab.
Ht 2 46.9* 220.6* 0.47 5.49* 0.03
Ht. I nc. 65.6* 294.8* 3.73* 3.71* 0.16
Dia. 2 14.0* 98.2* 3.41 3.71* 1.1
Dia. I nc. 19.7* 110.2* 4.6* 3.6* 1.41
Root (g) 5.89* 6.9* 0.01 2.73 0.08
Shoot(g) 16.9* 123.3* 0.84 2.18 0.3
6
7
8
9
10
Root
wei
ght
CD WD CW WW
Stable
Unstable
15
20
25
30
35
Shoo
t wei
ght
(g)
CD WD CW WW
Treatment
Stable
Unstable
Cold hardiness and stability
• 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
010203040506070
Col
d i
njur
y (%
)CD WD CW WW
Treatment
Stable
Unstable
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
300
350
400
450
CD WD CW WW
‘Stable’
‘Unstable’
Reaction norms for temperature• The unstable parents selected
produce progeny with higher mean growth rates under poorer growth conditions (lower temperature and moisture)
• However, whether unstable genotypes have Type 1 stability (consistent performance) at higher temperatures depends on the norms of reaction to temperatures above those tested
300
350
400
450
Cold Hot
Unstable Stable
Low test temp.
High test temp.
Conclusions• Douglas-fir families contributing to genotype-by-
environment 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
• Jack Woods, BC Ministry of Forests• Alvin Yanchuk, BC Ministry of Forests• Sonya Budge, UBC• Joanne Tuytel, UBC• Glen Reid, UBC• Corinne Stavness, UBC
