pre and postharvest management of aflatoxin contamination in groundnut f waliyar, b r natre, a...
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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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