Designing Crops for Variable Environments Prof. Martin S Wolfe Elm - - PowerPoint PPT Presentation

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Designing Crops for Variable Environments

• Prof. Martin S Wolfe

Elm Farm Research Centre Wakelyns Agroforestry

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What is special about conventional systems?

HGCA conventional wheat trials over 5 years

6 6.5 7 7.5 8 8.5 9 9.5 10 10.5 11

Xi19 Solstice Hereward Variety yield t/ha

Fungicide Treated Fungicide Untreated

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Conventional systems

High yields are produced by: a) High inputs to try to eliminate any limits to production b) Varieties bred to respond to such high inputs: high HI But the costs are high…..and increasing

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Are organic systems different?

Small Plot Replicated Trials in 2004 Mean Variety Grain Yield, LSD = 0.66

3.5 3.78 3.96 4.24

3 3.5 4 4.5 5

Xi19 Solstice Mix Hereward

Variety

t/ha

Small Plot Replicated Trials in 2003 Mean Variety Grain Yield

3.23 4.11 4.45

3 3.5 4 4.5 5 Xi19 Solstice Hereward

Variety t/ha

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Organic varieties?

Comparisons of winter wheat trials indicates three classes of variety: A) Good under conventional AND organic conditions (Claire, Deben) B) Good under conventional BUT LESS SO under organic conditions (Solstice, Xi19) C) Poor under conventional BUT GOOD under

• rganic conditions (Hereward, Spark)

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• So, wheat varieties respond

differently to organic conditions generally, and to the variation in

• rganic conditions
• How are such responses

expressed?

• And on what scale?

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DEFRA OF0330 Participatory research: a simple wheat trial on 15 organic farms

There was much variation in yield, due to:

• Variable fertility
• Rotational

position

• Variable weed

loading

• Other interacting

factors

Mean Grain Yield (t/ha), LSD = 0.62

2.3 2.3 2.4 2.5 3.0 3.5 3.7 3.8 4.0 4.3 4.7 4.9 5.3 5.8 5.8

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0 A B C D E F G H I J K L M N O

Site

t/ha

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‘Tall’ and ‘Short’ sites (OF0330)

Straw height versus grain yield correlation (N.S.)

10 20 30 40 50 60 70 80 90 0.0 2.0 4.0 6.0 8.0 10.0 Yield (t/ha) Straw height (cm)

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Wheat yields at 7 ‘Tall’ sites compared with 8 ‘Short’ sites

Grain yields for all varieties 3.9 3.4 3.5 3.6 4.4 4.2 4.4 3.9 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Hereward Mixture Solstice Xi19 Variety Grain yield (t/ha at 15% moisture) Tall sites Short sites

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Straw lengths and numbers of heads at 7 ‘Tall’ and 8 ‘Short’ sites

Straw length for varieties at tall and short sites

63.5 67.9 68.4 72.2 32.3 34.2 33.4 35.6 10 20 30 40 50 60 70 80 Hereward Mixture Solstice Xi19 Variety Mean straw length (cm) Tall sites Short sites

Number of heads per sqm for varieties at tall and short sites

427 475 366 411 748 678 757 586 100 200 300 400 500 600 700 800 Hereward Mixture Solstice Xi19 Variety Mean head density (heads/m2)

Tall sites Short sites

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Total straw length per square metre for varieties at tall and short sites

284 340 257 305 241 231 219 205 50 100 150 200 250 300 350 400 Hereward Mixture Solstice Xi19 Variety Total straw length (m)

Tall sites Short sites

Correlations of weed cover with straw length per sq m.

Hereward Mixture Solstice Xi19 Hereward Mixture Solstice Xi19

• 1
• 0.8
• 0.6
• 0.4
• 0.2

0.2 0.4 Tall sites Short sites

Cumulative straw length and the correlation with weed cover

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Varieties clustered by tall/short plant and low/high yield sites

10 20 30 40 50 60 70 80 90 2 2.5 3 3.5 4 4.5 5 5.5 6 Yield (t/ha) Straw height (cm)

Mix, So, Xi, He Xi, Mix, So, He Xi, So, Mix, He Xi, So, He, Mix

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Varieties clustered by yield (t/ha) and numbers of heads per sq m.

• No. heads vs Yield

100 200 300 400 500 600 700 800 900 1 2 3 4 5 6 Yield t/ha

• No. heads per sq m

L/S L/T H/T H/S

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Dynamics of “Harvest Index” for variety means at the four site clusters

Yield vs CSL

10 20 30 40 50 60 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00 Yield t/ha Cumulative straw length m/m2

S/H T/H S/L T/L “Harvest Index”

Length per sq m Short sites Length per sq m Tall sites Low Yield 1.39 1.45 High Yield 2.33 1.06

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What happened ?

• Distribution of resources among numbers of

grains, numbers of heads and length of straw was highly variable among sites

• BUT all varieties followed a similar pattern of

variation

• Hereward performed better than Xi19: more

plastic genotype

• Environmental effects (4 t/ha) were much

greater than genotypic (0.5 t/ha)

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How should we deal with such variation in organic systems?

• By improving fertility amount and dynamics
• By breeding/choosing appropriate varieties with

plastic response

• By using heterogeneous crops with built in

adaptability such as variety mixtures, species mixtures and crop populations

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High, stable yield from 3-variety wheat mixture

HeMaSh mixture '00 4.07; '01 2.53; '02 3.99; '03 3.47 t/ha

0.0 20.0 40.0 60.0 80.0 100.0 120.0 140.0 Shamrock Malacca Hereward HMS % of component means

101 95 104 110

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DEFRA AR 0914 Composite Cross: Selection of Parent Lines

High Yield Potential 1 Bezostaya 2 Buchan 3 Claire 4 Deben 5 High Tiller Line 6 Norman 7 Option 8 Tanker 9 Wembley Thatcher 12 Spark 11 Soissons 10 Renesansa 9 Renan 8 Pastiche 7 Monopol 6 Mercia 5 Maris Widgeon 4 Hereward 3 Cadenza 2 Bezostaya 1 High Quality Potential

Plus 4 male sterile lines

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Composite crosses: plant populations under conventional and organic conditions

Change in plant numbers per sq. m.

50 100 150 200 250 Early Final

Conventional Organic

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Yield development of composite cross populations under conventional and organic conditions

Composite Cross F3 under conventional and

• rganic conditions

100 200 300 400 500 600 700 800

• No. plts E
• No. plts L

Ears/sqm Yld g/sqm

Conventional Organic

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Performance of Composite Cross population in first field season

YQ Composite Cross population (F3) compared with physical mixture

100 200 300 400 500 600 700 800 Convent Organic Convent Organic Convent Organic Early plant nos. Ears/sqm Yield g/sqm Mix Comp CompMS

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Conclusions…

• Organic systems are highly variable: they

demand fundamentally different varieties from conventional systems

• Improvements in the dynamics of soil fertility

are needed

• Some conventionally bred varieties can be

relatively effective under organic conditions

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Conclusions…

• Inter-cropping with legumes needs further

development

• Variety mixtures can be helpful – if the right

components are available

• Composite cross populations offer potentials

for adaptable crops and for rapid production

• f adapted genotypes