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Synergistic Effect of

Resistant Maize Synthetics

and Aflasafe Application

Joseph Atehnkeng

For the team

Development of aflatoxin-resistant varieties

www.iita.org A member of CGIAR consortium Nestle visit 23-24 Jan . 14

Breeding may target:

• Direct selection for resistance to fungus and

aflatoxin accumulation

• Indirect selection for resistance or tolerance to

biotic and abiotic stresses.

• Selection for morphological traits such as ear,

kernel, and husk characteristics that impede

or delay fungal introduction or growth.

Technology-implementation challenges

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• Accumulation of aflatoxins in maize occurs following a complex

series of interactions

• Among maize

• The environment

• The pathogen

• insects

• Crop-management practices.

• Selection must be done simultaneously for multiple stresses in

order to combine drought and heat tolerance, resistance to

insects (especially ear-feeding insects), and resistance to the

pathogen.

• These stress tolerances must be combined with improved

agronomic performance in new maize varieties for adoption of

aflatoxin-resistant cultivars to occur, as farmers will not grow low-

yielding varieties regardless of aflatoxin resistance.

334 396 400 488 800 809 816 956

5474 5671

6438 6087

5685

7115

6040 5891 5743

5662

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

Hybrids

Aflatoxin (ppb)

Grain yield (kg/ha)

Afl

ato

xin

(p

pb

)

Gra

in y

ield

(kg

/ha)

Less Aflatoxin Susceptible, High-Yielding Yellow Maize Hybrids

Less toxin – high yield

Product: Aflasafe

Mixture of 4 native atoxigenic strains

Nigeria

How Does aflasafe Work?

Broadcast

@ 10 kg/ha 2-3 weeks

before flowering

Sporulation on moist soil

Spores

Insects

Aflasafe in 5 kg boxes

3-20 days

Wind

Soil

colonization

30-33 grains m-2

Fungal network in killed grain

75

94 100

0 3

39

73

27

0

20

40

60

80

100

120

<4 <10 <20 >20

Nestlé/EU WFP/Nigeria US Unsafe

Maximum allowable aflatoxin level (ng g-1)

Farm

ers

' fi

eld

s (

%)

Treated

Control

Different Levels of aflatoxin

in AflaSafe™ treated and

untreated fields at harvest

Objective

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• To evaluate the combined effect of

aflasafeTM and aflatoxin resistant

hybrid to reduce aflatoxin reduction.

Field Layout

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10 x 7.5 m

Alley

Alley Alley

Alley

Alley

Alley

10 x 7.5 m

Treated area with aflasafe

Untreated area

•2010 = 3 location

•2011 = 9 locations

• Maize varieties

• AFLTOXINRSYN3-W

• AFLTOXINRSYN2-Y

• AFLTOXINRSYN2-Y

•TZB-SR

• Replicated 6 times

• Aflasafe applied at 40

DAP

A t Maturity

• 25 maize cobs collected

from each plots at harvest

• Analyzed for aflatoxin

Biocontrol x Resistance

Experimental variety

At harvest

Control Aflasafe

RSYN2-Y 19.6 1.7

RSYN3-W 6.9 1.8

SYN3-Y 18.4 1.7

TZB-SR (susc.) 57.5 4.7

After poor storage

Control Aflasafe

462 44

627 38

387 19

1152 163

Combining management tactics increases extent of aflatoxin reduction

Aflatoxin (ppb) in Low-Aflatoxin Maize Lines With and Without Aflasafe Treatment

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Experimental varieties

Aflatoxin reduction (%)

Resistance alone

Biocontrol alone

Resistance + Biocontrol

RSYN2-Y 66 (60) 91 (90) 97 (96)

RSYN3-W 88 (46) 74 (94) 97 (97)

SYN3-Y 68 (66) 91 (95) 97 (98)

TZB-SR (Susc.) 58 (1152) ppb 92 (86)

% Reduction in experimental varieties compared to susceptible variety (TZB-SR) under natural conditions

% Reduction in varieties with biocontrol compared to susceptible variety (TZB-SR) under natural conditions

% Reduction in biocontrol treated plots compared to control plots of the same experimental variety

% Reduction in varieties with biocontrol compared to susceptible variety (TZB-SR) under natural conditions

% Reduction in biocontrol treated plots compared to untreated plots of the same variety

Synergistic Effect of Resistance and

Biocontrol in Reducing Aflatoxins at Harvest and after poor storage

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Aflasafe and Cultivar Interactions

Experimental variety

WithoutAflasafe

With Aflasafe

Reduction (%)

RSYN2-Y 18 (aA) 0 (aB) 100 (a)

RSYN3-W 57 (bA) 2 (bB) 96 (b)

SYN3-Y 36 (aA) 0 (aB) 100 (a)

TZB-SR (susc.) 67 (bA) 3 (bB) 96 (b)

Aflatoxin (ppb) in Low-Aflatoxin Maize Lines With and Without Aflasafe Treatment in Shika

Means within a column with same lowercase letter, and means of treated-control pairs

within a row with the same uppercase letter are not significantly different; P < 0.0001

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Conclusion

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A combination of the two technologies

reduces aflatoxins by more than 90 %

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Thank you

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Background

• Pre-harvest host resistance

• Though commercial varieties are not yet available

effort are in progress

Experiment layout

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•In Kaduna State

• In 2010 = 3 locations

• In 2011 = 9 locations

• Maize varieties

• AFLTOXINRSYN3-W

• AFLTOXINRSYN2-Y

• AFLTOXINRSYN2-Y

• TZB-SR

Generation of resistant germplasm

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Methods to achieve resistance to A. flavus and

aflatoxin accumulation include:

• Prevention of fungal infection of maize, which is

especially important under stressed environmental

conditions

• Prevention of subsequent growth of the fungus

once infection has occurred

• Inhibition of aflatoxin production following

infection

• Degradation of aflatoxins by the plant or fungus.