Pre and Postharvest Pre and Postharvest Management of Aflatoxin Management of Aflatoxin

Contamination in GroundnutContamination in GroundnutF Waliyar, B R Natre, A Traoré,

B Diarra, O Kodio and P Lava Kumar

International Crops Research Institute for the Semi-Arid TropicsInternational Crops Research Institute for the Semi-Arid Tropics

Institut d'Economie Rurale (IER), Mali Institut d'Economie Rurale (IER), Mali

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www.aflatoxin.infowww.aflatoxin.info

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GroundnutGroundnut

Groundnut / Peanut (Arachis hypogea)

• Major oilseed crop in the tropical and semi-tropical parts of the world

-Major producers are India, China and the USA-Major producers are India, China and the USA

-Nigeria, Senegal, Sudan and Argentina-Nigeria, Senegal, Sudan and Argentina

• Developing countries account for 95% global production

-70% in Asia, 23% in Sub-Saharan Africa (SSA)

-West Central Africa (WCA) accounts for 78% of total SSA production

• About 95% of the groundnut produced serves subsistence needs and domestic markets

• Important in small-holder agriculture, grown mostly under subsistence conditions

• A major source of income especially for women

• Increasing shift towards edible groundnut (food purpose)

(209% increase in West Africa during the past 3 decades)

Source of: Digestible protein (24-34%) Fat (44-56%) Carbohydrate (11-27%) Vitamins Meal and Fodder Nitrogen fixation (60 kg/ha)

Importance of GroundnutImportance of Groundnut

Aflatoxins are produced by A. flavus / A. parasiticus

Grows over a wide range of temperature (between 10-40°C)

Thrives at high relative humidity and kernel moisture content (10 to 30%)

Aflatoxins in GroundnutAflatoxins in Groundnut

Can occur at all stages: pre-harvest, harvest, and storage

Accumulates in seeds

Deteriorate quality

Barrier to international trade

Cause serious health risks of various kinds, accounting for several deaths in Africa

Aflatoxins in GroundnutAflatoxins in Groundnut

Aflatoxin Aflatoxin contamination contamination

Liver cancer &

other diseases

Tra

de

rest

rict

ion

Enhances HIV/AIDS

Mal

nutr

ition

Status in AfricaStatus in AfricaEndemic problem especially in Sub-Saharan Africa (SSA),

- Due to frequent droughts and cultivation under subsistence conditions

Pre-harvest contamination is the major source: -End-of-season drought; mechanical damage to pods; poor harvesting and

storage methods

High contamination in seeds -Reduction in exports by 19% during past 2-decades

Lack of awareness and monitoring facilities -For most countries specific aflatoxin regulations do not exist -Regulations will have limited effect on health protection, as groundnut produced is mainly consumed by the producers themselves No regulations

Regulations in placeNo information available

FAO, 2004

Predisposing FactorsPredisposing Factors• Drought stress

• Weather conditions during pod maturation and during drying

• Time of harvest

• Method of harvest/drying

• Time of pod removal

• Insects damage

• Storage conditions

Aflatoxin Management Aflatoxin Management Strategies Strategies Resistance

Conventional , Transgenics

Harvesting and Postharvest Drying, Threshers, Storages

Bio-control agentsTrichoderma

Pseudomonades

Agronomic and Cultural practices

Soil amendments (lime, farmyard manure,

crop residues, etc)

Pre and PosharvestPre and PosharvestAflatoxin managementAflatoxin management

Strategy for Aflatoxin Strategy for Aflatoxin Management in SSA Management in SSA Reduce aflatoxin contamination to improve health and

incomes of groundnut farmers and consumers• Promote pre and post-harvest technologies that minimize

aflatoxin contamination of groundnuts• Information dissemination• Awareness campaigns

Participatory varietal selection of tolerant varieties

Participatory evaluation of cultural practices to reduce aflatoxin contamination

Demonstration of best-bet harvest and drying techniques

Training for technology dissemination

Conventional resistanceConventional resistance

Source of resistance available

Low level of resistance

Breeding lines developed

Some have been tested in Asia and Africa

High yielding lines identified

• Difficulties

• Screening

• Variability (field)

(i) Resistance(i) Resistance

Transgenic resistanceTransgenic resistance

Incorporation of anti-fungal genes (Chitinase) in elite varieties (cv. JL24)

T1 generation plants being evaluated for resistance.

The main objective is to reduce effect of The main objective is to reduce effect of drought at the end of cropping seasondrought at the end of cropping season

Farmyard manure Calcium (as lime/gypsum applications)Cereal Crop ResiduesDensityPlanting date etc.,

(ii) Agronomic and Cultural Practices(ii) Agronomic and Cultural Practices

(iii) Soil Amendments to (iii) Soil Amendments to Mitigate Aflatoxin Mitigate Aflatoxin

ContaminationContamination• On station experiments conducted at Sadore, Niger and Samanko,

Mali, during 1999-2001

• Soil amendments with lime (2.5 t hat-1), farmyard manure (10 t ha-1) and cereal crop residues (5 t ha-1) applied at sowing or 50 days after sowing, either individually or combinations of these three (12 treatments).

• Three cultivars used: Two resistant cultivars, J11 and 55-437; and a susceptible cultivar Fleur 11

Aflatoxin Concentration (ppb) in Aflatoxin Concentration (ppb) in Groundnut Seeds from Various Groundnut Seeds from Various

TreatmentsTreatments

*Three year average

Treatment Samanko (Mali) Sadore, (Niger)

55-437 J11 Fleur 11 55-437 J11 Fleur 11

L1 6.0 9.1 22.6 3.5 4.9 16.7

L2 10.8 8.9 173.6 2.9 4.2 9.5

R1 10.5 12.7 155.8 9.7 9.6 45.9

R2 22.9 15.6 216.3 4.5 6.6 18.5

F1 9.5 9.8 135.4 4.8 5.2 18.4

Control 13.2 14.5 269.7 7.4 6.4 56.1

F = Farmyard manure R = crop residues L = Lime

1 = Application at sowing2 = Application at 50 days after sowing

Resistant cvs. 55-437 and J11 Susceptible cv. Fleur 11

Aflatoxin Concentration (ppb) in Aflatoxin Concentration (ppb) in Groundnut Seeds from Various Groundnut Seeds from Various

Treatment CombinationsTreatment Combinations

*Three year average

F = Farmyard manure R = crop residues L = Lime

1 = Application at sowing

2 = Application at 50 days after sowing

Samanko (Mali) Sadore (Niger)

Treatments 55-437 J11 Fleur 11 55-437 J11 Fleur 11

F0 R1 L1 3.7 4.9 14.1 5.8 6.1 19.1

F0 R1 L2 3.5 5.4 64.1 6.4 8.8 41.4

F0 R2 L1 10.9 13.4 85.4 3.0 4.9 14.2

F0 R2 L2 12.8 13.5 36.2 3.1 4.9 30.9

F1 R0 L1 5.0 4.3 17.4 3.9 2.9 12.9

F1 R0 L2 6.1 6.4 97.8 4.1 2.9 11.5

F1 R1 L0 7.1 8.5 123.8 3.8 6.5 43.8

F1 R1 L1 2.6 2.3 11.8 4.1 5.2 35.8

F1 R1 L2 2.5 4.6 16.6 5.4 4.2 23.1

F1 R2 L0 13.7 10.1 35.2 3.6 6.5 18.5

F1 R2 L1 5.4 6.6 19.0 2.7 5.9 14.4

F1 R2 L2 7.1 8.5 18.7 2.2 3.7 14.8

Control 13.2 14.5 269.7 7.4 6.4 56.1

Resistant cvs. 55-437 and J11 Susceptible cv. Fleur 11

Promising Soil Amendments for Promising Soil Amendments for Reducing Aflatoxin Contamination in Reducing Aflatoxin Contamination in

GroundnutGroundnutSamanko, MaliSadore, Niger

0

100

200

300

L1 R1L1

F1 L1

F1 R1 L1

F1 R1 L2

F1 R2 L1

F1 R2 L2

Control

Afl

ato

xin

s (p

pb

)*

F = Farmyard manure R = Cereal crop residues L = Lime

1 = Application at sowing2 = Application at 50 days after sowing

*Three year average

Average from 3 years on-station trials (1999-2001)Groundnut cv. Fleur 11 (Highly susceptible to aflatoxin)

25

A resistant (55-437) and a susceptible (JL 24) cvs used in the study

Demonstrations in farmers in Kolokani and Kayes; on-station

400 kg ha-1 lime applied at 50 days after sowing

2.5 t of Crop residues and farmyard manure at planting and 50 days after sowing

Effect of Lime, Crop Effect of Lime, Crop Residues and Farmyard Residues and Farmyard

Manure in Farmers FieldsManure in Farmers Fields

Aflatoxin Content Under Aflatoxin Content Under Various Agronomic Practices Various Agronomic Practices

in Kayes (Mali)in Kayes (Mali)

TreatmentTreatment

Aflatoxin content (ppb)Aflatoxin content (ppb)

55-43755-437(Resistant cv.)(Resistant cv.)

JL24JL24(Susceptible cv.)(Susceptible cv.)

Lime 0.12 4.20

2.5 t ha-1 F 0.26 6.76

2.5 t ha-1 R 0.79 36.71

Lime +R 0.36 7.36

F + R 0.94 12.10

Control 2.83 82.32

SE 1.564

F = Farmyard manureR = Crop residues

Aflatoxin Content Under Aflatoxin Content Under Various Agronomic Various Agronomic Practices in KolokaniPractices in Kolokani

TreatmentTreatment

Aflatoxin content (ppb)Aflatoxin content (ppb)

55-43755-437 JL24JL24

Lime 50 days after planting 1.9 52.3

2.5 t ha-1 F 2.0 64.0

2.5 t ha-1 R 3.3 126.6

Lime +CR 2.8 79.5

F + R 4.2 90.6

Control 6.2 190.8

SE 1.22

FYM = Farmyard manureCR = Crop residues

Method of Harvesting Method of Harvesting and Dryingand Drying

• Demonstration in farmers in Kolokani and Keyes, Mali

• Drying pods facing the sun

Traditional Field Drying

Improved Batch Drying(Pods facing the sun)

Effect of Method of Drying Effect of Method of Drying on Aflatoxin Content - on Aflatoxin Content -

KolokaniKolokani

FarmerFarmer

cv. 55-437cv. 55-437 cv. 47-10cv. 47-10Traditional*Traditional* Improved* Improved* Traditional*Traditional* Improved* Improved*

Bagui 1.45 0.58 17.94 2.22

Mory 3.24 1.45 13.73 1.78

Seba 1.01 0.00 15.93 4.97

Demaba 1.50 0.78 14.61 3.89

*parts per billion

Effect of Method of Drying on Aflatoxin

Content - KayesKayes

FarmerFarmer

cv. 55-437cv. 55-437 cv. 47-10cv. 47-10

TraditionalTraditional ImprovedImproved

(Percent reduction)(Percent reduction)

TraditionalTraditional ImprovedImproved

(Percent reduction)(Percent reduction)

Savado 8.08 3.03 (63) 60.08 18.01 (70)

Coumb 9.90 2.32 (77) 59.62 15.73 (74)

Kande 8.01 1.67 (79) 44.86 14.28 (68)

Seydou 5.78 0.31 (95) 12.32 1.96 (84)

Yaya 5.70 2.17 (62) 58.01 21.53 (63)

*parts per billion

Effect of Time of Pod Effect of Time of Pod Removal on Aflatoxin Removal on Aflatoxin

ContentContent

• Lifting at maturity

• Remove pods immediately• After 1 week• After 2 weeks• Usual farmers practice

(when ready)

Time of Pod Removal After Time of Pod Removal After UprootingUprooting

TreatmentTreatment

Aflatoxin content (ppb) Aflatoxin content (ppb)

Resistant cultivars Susceptible cultivars

55-43755-437 J11J11 JL24JL24 Fleur 11Fleur 11

0 weeks 4.5 3.6 90.5 117.7

1 Week 6.3 5.7 152.4 199.5

2 weeks 7.40 6.1 244.4 295.2

Farmer 8.7 7.1 316.3 342.2

Gleans 11.5 6.6 382.9 412.8

Increase in Aflatoxin Increase in Aflatoxin Concentration During Storages Concentration During Storages

in the Farmers Fieldsin the Farmers Fields

VillageVillage

Aflatoxin content (ppb)Aflatoxin content (ppb)

At harvestAt harvest 1 month in 1 month in storagestorage

2 months in 2 months in storagestorage

Bamba (5) 101.3 168.9 275.5

Gouak (5) 61.4 118.0 174.7

Kolokani (5) 119.2 352.6 400.0

Sido (5) 53.7 93.6 166.2

• Increased awareness among farmers of the value of modern varieties and have responded by being directly involved in variety selection and seed production

• Farmers awareness of the needs of processors and consumers who in turn recognize the value of improved quality

Imparting AwarenessImparting Awareness

Information Dissemination Information Dissemination PathwaysPathways

• Use of farmer trial and demonstration plots through farmer-to farmer visits

• End of season meetings

• Brochures and flyers (Fr and local languages)

• Television and radio debates

Future Outlook Future Outlook • Risk assessment of mycotoxins in other crops in addition to groundnut

• Assess the impact of mycotoxins on human health and socio-economic conditions of people in marginal farming systems

• Increase public awareness on the risks of mycotoxins

• Develop and implement quality control methods and safety standards

• Develop and/or promote technologies to produce mycotoxin free products

• Study the impact of aflatoxin contaminated food on HIV/AIDS patients

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