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Pre and Postharvest Management of
Aflatoxin Contamination in Groundnut
F Waliyar, B R Natre, A Traoré,
B Diarra, O Kodio and P Lava Kumar
International Crops Research Institute for the Semi-Arid Tropics
Institut d'Economie Rurale (IER), Mali
www.aflatoxin.info
ICRISAT
ICRISAT
Groundnut
• Major oilseed crop in the tropical and
semi-tropical parts of the world
-Major producers are India, China and the USA
-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
Groundnut / Peanut (Arachis hypogea)
• About 95% of the groundnut produced serves subsistence
needs and domestic markets
Importance of Groundnut
• 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)
Aflatoxins in 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 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
Aflatoxin
contamination
Status in Africa
Endemic 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
FAO, 2004
No regulations
Regulations in place
No information available
Predisposing 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 Strategies
Resistance
Conventional , Transgenics
Agronomic and
Cultural practices
Soil amendments
(lime, farmyard manure,
crop residues, etc)
Pre and Posharvest
Aflatoxin management
Harvesting and Postharvest
Drying, Threshers, Storages
Bio-control agents
Trichoderma
Pseudomonades
Strategy for Aflatoxin 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
(i) Resistance
Conventional 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)
Transgenic resistance
Incorporation of anti-fungal genes (Chitinase) in elite varieties
(cv. JL24)
T1 generation plants being evaluated for resistance.
(ii) Agronomic and Cultural Practices
The main objective is to reduce effect of
drought at the end of cropping season
Farmyard manure
Calcium (as lime/gypsum applications)
Cereal Crop Residues
Density
Planting date etc.,
(iii) Soil Amendments to Mitigate
Aflatoxin Contamination
• 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 Groundnut
Seeds from Various Treatments
Treatment
Samanko (Mali)
55-437
J11
L1
6.0
9.1
22.6
L2
10.8
8.9
R1
10.5
R2
Sadore, (Niger)
J11
Fleur 11
3.5
4.9
16.7
173.6
2.9
4.2
9.5
12.7
155.8
9.7
9.6
45.9
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
Resistant cvs. 55-437 and J11
Susceptible cv. Fleur 11
F = Farmyard manure
R = crop residues
L = Lime
Fleur 11 55-437
*Three year average
1 = Application at sowing
2 = Application at 50 days after sowing
Aflatoxin Concentration (ppb) in Groundnut
Seeds from Various Treatment Combinations
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
*Three year average
F = Farmyard manure
R = crop residues
L = Lime
1 = Application at
sowing
2 = Application at 50
days after sowing
Promising Soil Amendments for Reducing
Aflatoxin Contamination in Groundnut
Aflatoxins (ppb)*
Samanko, Mali
Sadore, Niger
300
200
100
25
0
L1
R1
L1
F1
L1
F1
R1
L1
F1
R1
L2
F1
R2
L1
F1
R2
L2
Control
*Three year average
F = Farmyard manure
R = Cereal crop residues
L = Lime
1 = Application at sowing
2 = Application at 50 days after sowing
Average from 3 years on-station trials (1999-2001)
Groundnut cv. Fleur 11 (Highly susceptible to aflatoxin)
Effect of Lime, Crop Residues and
Farmyard Manure in Farmers Fields
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
Aflatoxin Content Under Various
Agronomic Practices in Kayes (Mali)
Aflatoxin content (ppb)
Treatment
55-437
JL24
(Resistant 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 manure
R = Crop residues
Aflatoxin Content Under Various
Agronomic Practices in Kolokani
Aflatoxin content (ppb)
Treatment
55-437
JL24
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 manure
CR = Crop residues
Method of Harvesting and
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 on
Aflatoxin Content - Kolokani
cv. 55-437
Farmer
cv. 47-10
Traditional*
Improved*
Traditional*
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 - Kayes
cv. 55-437
Farmer
cv. 47-10
Traditional
Improved
(Percent reduction)
Traditional
Improved
(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 Removal
on Aflatoxin Content
• Lifting at maturity
•
•
•
•
Remove pods immediately
After 1 week
After 2 weeks
Usual farmers practice
(when ready)
Time of Pod Removal After Uprooting
Aflatoxin content (ppb)
Treatment
Resistant cultivars
Susceptible cultivars
55-437
J11
JL24
Fleur 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 Concentration
During Storages in the Farmers Fields
Aflatoxin content (ppb)
Village
At harvest
1 month in
storage
2 months in
storage
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
Imparting Awareness
• 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
Information Dissemination Pathways
• 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
• Risk assessment of mycotoxins in other crops in addition to
groundnut
• Assess the impact of mycotoxins on human health and socioeconomic 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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