A presentation at the WCCA 2011 event in Brisbane.

1. Genetic control of wheat
adaptation to conservation
agriculture
Richard Trethowan, Tariq Mahmood, Zulfiqar Ali, Klaus Oldach

2. Implications of breeding crops
adapted to conservation tillage
• New diseases (tan spot,
root rots etc)
• More challenging seed
bed
• Weed competition
• Changes in nitrogen
management (N-use
efficiency)
• Tillage x cultivar
interaction

3. Published examinations of genotype x
tillage interactions
Crop Genotype Literature
x Tillage
Wheat +/- Gutierrez (2005); Cox (1991)
Barley - Ullrich & Muir (1986)
Sorghum - Francis et al. (1985)
Maize +/- Newhouse (1985); Brakke et al (1983);
Newhouse & Crosbie (1983)
Rice - Melo et al (2005)
Soybean - Elmore (1990); Pfeiffer (1987)
Pulses ? NA

4. Gutierrez (2005):
Genotype x tillage study in wheat in Mexico
Diverse set of wheat cultivars:
Berkut, Sokoll, Kambara, Weebill 1, Rebeca F20006, Romoga
F96, Nahuatl F2000, Juchi F2000, Temporalera M87,
Tlaxcala F2000
Diverse environments:
Irrigated & rainfed over two years

5. Analysis of variance; El Batan 2003 and
2004 – rainfed (Gutierrez, 2005)
Mixograph
Yield Biomass TKW P% SDS Height Mixing Stability
time
Year ** ** ** ** ** ns ns **
Tillage ** ** ns ns ** * * ns
Cultivar ** ** ** ** ** ** ** **
Cultivar x Year ** ** ** ** ** ** ** **
Cultivar x ** * ** ** ** ns ns **
Tillage
Cultivar x Till x ns ns ** ns * ns ns ns
Year

6. Wheat grain yield for different tillage and planting
methods at El Batan (Mexico) over 2 years
2500
2000
Yield kg/ha
1500
1000
500
a b b b
0
ZT flat ZT beds CT flat CT beds
ZT = zero tillage; CT conventional tillage

7. Yield of a common set of 50 genotypes under
contrasting tillage regimes in Australia and Mexico
over 2 years
• Higher yields under
7000 zero-till
Mexico
6000 • No significant
Yield kg/ha
5000 genotype x tillage
Australia interaction in Mexico
4000
(NS)
3000
2000
1000
Zero Till
2 7
2 7
2 8
2 8
2 7
2 7
2 8
8
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Comp
2
Till
Source: Trethowan & Manes

8. Can a genotype x tillage interaction be designed?
Five crosses among lines with
contrasting responses under zero-
tillage
Always selected under Always selected under
zero-tillage alternating conventional tillage
between rainfed and alternating between rainfed
irrigated conditions and irrigated conditions
Advanced lines from both selection
regimes evaluated under both zero
and conventional tillage
Sayre & Trethowan

9. Effects of Cross and Selection System on Grain Yield
Averaged over 2005, 2006 and 2007
Cross x Selection System LSD (0.05) = 143 kg/ha
6400
6200
Grain yield (kg/ha)
6000
5800
5600
5400
5200 a b a b a a a a a a
5000
SERI/..BERKUT SW94.../PBW65 FILIN./PASTOR MILAN./PASTOR PFAU../AMAD
Cross
ZERO TILL SELECTION CONV TILL SELECTION

10. Genetic variability for
improved adaptation to
conservation agriculture

11. Traits important in crop emergence & establishment
Trait Recent evidence
Coleoptile length Trethowan et al (2001); Rebetzke et al (2004
& 2007); Erayman et al (2006)
Coleoptile thickness Rebetzke et al (2004)
Emergence from depth Trethowan et al (2005); Joshi et al (2007)
Rapid height growth Olesen et al (2004)
Seedling vigour Liang and Richards (1999); Trethowan et al
(2005); Erayman et al (2006)
Kernel weight & embryo size Liang and Richards (1999)
Faster stubble decomposition Joshi et al (2007)
Weed suppression & Allelopathy Olesen et al (2004); Bertholdsson, 2005
Early biomass/specific leaf area Liang and Richards (1999); Olesen et al
(2004)
Deeper roots Reynolds and Trethowan (2007)
N-use efficiency Van Ginkel et al (2001); Trethowan et al
(2005)
Disease resistance Trethowan et al (2005); Joshi et al (2007)
Seedling temperature tolerance Boubaker & Yamada (1991); Dell’Aquila and
Spada (1994)

12. Useful sources of
genetic variability in
wheat
+
• Cultivars released in areas where farmers
have adopted CA
• Hexaploid primary synthetics
AB D
• Landraces
T. durum A. tauschii
• Translocations from wild relatives
• Alternative dwarfing genes
• Sources of resistance to foliar blights and
root rots
ABD

13. Effect of different height reducing
genes on coleoptile length in wheat
Rht gene GA insensitive GA sensitive
(-) coleoptile (+) coleoptile
Rht-B1b X
Rht-D1b X
Rht 7 X
Rht 8 X
Rht 9 X
Rht 12 X
Source: Rebetzke et al 2004. 2007

14. Genotype x tillage practice trials on two soil types at
Narrabri:
Berkut/Krichauff mapping population (160 lines)

15. Mean yield across tillage regimes,
years and soil types at Narrabri
Tillage Zero till Conven till P<
regime
Heading (days) 108.5 a 109.1 b 0.05
Yield (kg/ha) 1702 a 1368 b 0.001
Soil type Grey vertisol Red kandosol
Heading (days) 109 a 108.6 a ns
Yield (kg/ha) 1733 a 1337 b 0.001

16. The yield difference between zero-tillage (ZT) and
conventional tillage (CT): means based on 2 sites in
2 years.
800
Yield difference kg/ha (ZT-CT)
600 Krichauff
400
200
Berkut
0
0 20 40 60 80 100 120 140 160
-200
-400
-600
Genotype

17. Significant QTL effects for yield under contrasting
tillage regimes on two soil types in 2 years
Chr Interval Treatment Soil type Additive Allele
effect %
1B gwm268/wPt-3475 CT Grey v 8 K
1B wPt-1313/gmw140 CT Grey v 10 K
1D cdf19/wmc216 CT Red k 10 K
2D wPt-3728/cfd44 ZT Grey v 9 K
2D gmw484/wmc27 ZT Red k 9 B
5A cfa2155/wPt1370 ZT Grey v 25 B
5A cfa2115/wPt1370 CT Grey v 14 B
5A cfa2115/wPt1370 CT Red k 9 B
5B wmc99/wPt2373 ZT Grey v 12 B

18. Select diverse germplasm & screen for response to tillage measuring
yield, disease and product quality to determine the extent of genotype
x tillage interactions.
Combine in crosses Identify parents with
with emphasis on extreme trait
adaptation to the expression. Include
target conditions & parents with
QTLs complementary QTLs
Implement a selection Evaluate fixed lines
strategy. Eg combine across a range of
deep planting in a zero- conservation agricultural
tillage system with practices in multi-
disease inoculation & locational trials in the
marker assisted sel. target region.
Select lines with high yield,
appropriate quality and stable
performance across farmer
practices within the target
region for release.

19. Acknowledgments:
CIMMYT – Yann
Manes/Ken Sayre/Bram
Govaerts
SARDI – Klaus
Oldach, Hugh Wallwork
Team at PBI Sydney &
Narrabri
Molecular Plant Breeding
CRC