Bioreactors for the rapid mass micropropagation of yam

< ![endif]–>

Morufat Balogun, m.balogun@cgiar.org

The tissue culture technique using meristems followed by serial nodal cultures can be effective for producing high quality seed yam but its use is limited by the slow rate of regeneration and propagation in a conventional semi-solid culture medium. Conventional tissue culture employs manual introduction into culture vials. However, the slowness of yam propagation in vivo also occurs in vitro where cultures for some genotypes can take more than 1 year to regenerate from meristems. This low multiplication rate limits the use of in-vitro produced plantlets; there are also losses during acclimatization and transplanting. Other limitations resulting in low propagation rates are frequent sub-culturing which increases labor costs, culture container size (hence nutrients), and sub-optimal culture aeration and uptake (Cabrera et al. 2011).

As part of its objective to develop technologies for the high ratio propagation of high quality seed yam, YIIFSWA is set to standardize in vitro propagation techniques using conventional and temporary immersion technologies. In most crops tested (pineapple, cocoa, potato, and others), the Temporary Immersion Bioreactor system (TIB) increased propagation rates (Watt 2012) through culture aeration combined with automation, both of which increase productivity.

The TIB technology involves the timed immersion of plant tissues in a liquid medium to allow for the aeration of cultures. Each unit is a bioreactor—an enclosed sterile environment provided with inlets and outlets for air flow under pressure—and therefore circumvents the limitations associated with conventional tissue culture. Although the TIB system requires the interplay of plant physiology and the chemical and physical sciences, growth rate is significantly enhanced therein since gas exchange is guaranteed (Watt 2012).

IITA’s TIB system is a “twin flask” type (Adelberg and Simpson 2002), having 1 container for the medium and the other for the cultures. It has potentials for both plantlet and yam microtuber production which will facilitate the production of quality breeders’ seed yam from which healthy foundation and certified seed yam will be multiplied. IITA’s TIB is established with 128 units and, when running at full capacity, can produce at least 12,000 seed yam in 1 year. It is programmable and remotely controlled online. It can also be used to fast-track genetic improvement through accelerated in-vitro variations and selection. Seed yam from this technology will be bulked in IITA’s aeroponics facility; other end-users include researchers, farmers, and public/private seed companies.

References

Adelberg, J.W. and E.P. Simpson. 2002. Intermittent Immersion Vessel Apparatus and Process for Plant Propagation. Internl. S/N: PCT/US01/06586.

Cabrera, M., R. Gómez, E. Espinosa, J. López, V. Medero, M. Basail and A. Santos. 2011. Yam (Dioscorea alata L.) microtuber formation in Temporary Immersion System as planting material. Biotecnologia Apl. 28: 4.

Watt, M.P. 2012. The status of temporary immersion system (TIS) technology for plant micropropagation.African Journal of Biotechnology 11: 14025-14035.

 

Novel yam propagation technologies: the aeroponics system

Norbert Maroya, n.maroya@cgiar.org, Morufat Balogun, Lava Kumar, Robert Asiedu, and Beatrice Aighewi

Norbert Maroya, Project Coordinator, YIIFSWA; Morufat Balogun, Agronomist (YIIFSWA); Lava Kumar, Virologist and Head, Germplasm Health Unit; Robert Asiedu, R4D Director for West Africa, IITA; and Beatrice Aighewi, Seed Systems Specialist, YIIFSWA

The multiplication ratio of yam in the field is known to be very low (less than 1:10). The methods developed to address this limitation include the minisett technique, vine propagation, and micropropagation using in vitro culture of apical meristems and nodal cuttings. These methods are well suited to rapid multiplication of seed tubers for new and other recommended varieties, and are also amenable to the application of sanitary methods that ensure high seed quality. Other methods of rapid propagation developed at IITA include production of microtubers from plantlets in vitro, and the production of seed tubers using slips (sprouts) and peels. Other technologies also exist but are not yet being used for yam.

Three new technologies targeted to be implemented for seed yam propagation are aeroponics system (AS), temporary immersion bioreactor system (TIBs), and photoautotrophic culture (PC). These technologies are being tested under the Bill & Melinda Gates Foundation-funded project “Yam Improvement for Income and Food Security in West Africa (YIIFSWA)”. These technologies are known to be effective for other vegetatively propagated and horticultural crops for high ratio propagation and assurance of high seed quality. However, their cost-effectiveness for yam propagation is yet unknown. Very recently two of these technologies, AS and TIBs, have been established at IITA-Ibadan, Nigeria. Progress achieved with AS is summarized in this article.

What is an aeroponics system?
The basic principle of AS is growing plants in air in a closed or semi-closed environment without the use of soil or an aggregate media and spraying the plant’s roots with a nutrient-rich solution (mist environment). The techniques of growing plants without soil were first developed in the 1920s by botanists who used primitive aeroponics to study plant root structure. The aeroponics system has long been used as a research tool in root physiology (Barker 1922). Carter (1942) was the first researcher to study air culture growing and described a method of growing plants in water vapor to facilitate examination of roots. Went (1957) named the air-growing process in spray culture as “aeroponics”.

The International Union of Soil-less Culture defines aeroponics “as a system where roots are continuously or discontinuously in an environment saturated with fine drops (a mist or aerosol) of nutrient solution” (Nugali et al. 2005). AS has been used successfully in producing several horticultural and ornamental crops (Biddinger et al. 1998). It has also been applied successfully in Korea for potato seed tuber production (Kang et al. 1996; Kim et al. 1999). At the International Potato Centre (CIP) in Peru, yields of over 100 tubers/plant were obtained using aeroponics technology (Otazu 2010). Aeroponics technology is also being tested in several African countries for the production of potato mini tubers (Lung’aho et al. 2010).

IITA’s experience in propagating yam in AS

Seed yam production using aeroponics was initiated recently. A consultant from Kenya helped to establish an AS of 14 boxes of four tables each in an existing screenhouse at IITA, Ibadan, Nigeria, with an adjacent powerhouse as a source of the spray of nutrient-rich solution to the roots.

From yam seedlings transplanted in July 2012, vine cuttings were made on 6 to 19 December 2012 and planted in black plastic pots for pre-rooting. The pre-rooted vines were transplanted in AS on 26 to 28 February 2013. Vine cuttings were collected from other seedlings transplanted on 28 August 2012 and planted directly in AS on 1 March 2013.

Both pre-rooted and direct-planted vines have continued to grow normally in AS with the development of new shoots and roots. The two types of plants produced viable minitubers which were harvested in June 2013. The key finding in this experiment is the ability to root vine cuttings in AS. Within 10 days more than 50% of the vines produced roots and in 3 weeks 85–100% of the direct-planted vine cuttings produced roots in AS. If a yam plant is certified clean, one can directly collect vine cuttings from such plant for propagation in AS through vine cuttings.

This is the first report of successful yam propagation in AS. Also all previous studies on AS for potatoes or horticulture crops used transplants of rooted plantlets and not unrooted vine cuttings. This is the first experience using yam vine cuttings in AS. The minitubers harvested in June 2013 were planted in August 2013 and sprouted well.

Many of the farmer-preferred yam genotypes are also being evaluated in AS. Direct vine cutting of variety Puna—a popular cultivar in Ghana—was planted in AS on 10 July 2013 and harvested on 6 November 2013 (4 months).

Production of bulbils of yam in AS

The second set of experiments was done using only vine cuttings of plants produced in a glasshouse. To increase the size of mini tubers, two new fertilizers—potassium sulfate (K2SO4) and Triple Super Phosphate—were added to the existing nutrient solution. Between 45 and 60 days after vine cuttings were planted in AS we observed that many varieties of both D. rotundata (white yam) and D. alata (water yam) had produced bulbils. All the bulbils produced by D. rotundata were growing with new shoots and roots; it was the same for D. alata with most bulbils increasing in size. Bulbils mainly harvested from D. rotundata were planted in plastic bags, sprouted, and are growing normally.

Percentage of bulbils formed per genotype on AS

Genotypes

Number of plants

% of plants with bulbils

TDa 291

32

9.4%

TDa 98/01176

53

18.9%

TDr 02475

47

42.6%

TDr 89/02665

18

72.2%

TDr 95/18544

50

22.0%

TDr 95/19158

12

16.7%

TDr 95/19177

26

11.5%

Total

238

26.1%


Challenges

Ideally the AS environment should be kept free from pests and diseases so that the plants will grow healthier and quicker than plants grown in a soil medium. However, current arrangements do not provide an ideal environment due to lack of control on temperature and pest and disease infestation. Plants generated in AS were frequently infested (19 to 29%) by Colletotrichum sp. (both leaves and stem), Sphaerosporium sp. (stems) (typically saprophytic), and Fusarium sp. (stems). Steps are being taken toward reducing the heat inside the screenhouse with industrial fans and providing adequate shade. Measures are also being implemented to control infestation of fungal pathogens.

Conclusion

Despite the relatively recent (less than one year) attempt to propagate yam in AS, some of the results obtained so far are very encouraging and impressive. They have clearly shown that AS does not necessarily need rooted plantlets/vines for yam propagation. Micro-tubers, bulbils, and mini-tubers can be produced respectively within 2 and 4 months after vine cuttings are planted in AS.

References

Barker BTP. 1922. Studies on root development. Long Ashton Res. Station Ann. Rep. 1921: 9-57.

Biddinger E.J., Liu C.M.. Joly R. J, Raghothama K.G. 1998. Physiological and molecular responses of aeroponically grown tomato plants to phosphorous deficiency. J. Am Soc. Hortic. Sci. 123: 330-333

Carter W.A. 1942. A method of growing plants in water vapor to facilitate examination of roots. Phytopathol. 732: 623-625.

Lung’aho C., Nyongesa M., Mbiyu M.W., Ng’ang’a N.M.. Kipkoech D.N., Pwaipwai P., Karinga J. 2010. Potato (Solanum tuberosum) minituber production using aeroponics: another arrow in the quiver? In: Proceedings of the 12th Biennial Conference of the Kenya Agricultural Research Institute.

Kang J.G., Kim S.Y.; Om Y.H., Kim J.K. 1996. Growth and tuberization of potato (Solanum tuberosum L.) cultivars in aeroponic, deep flow technique and nutrient film technique culture films. J. Korean Soc. Hort. Sci. 37: 24-27.

Kim H.S., Lee E.M., Lee M.A., Woo I.S., Moon C.S., Lee Y.B., and Kim S.Y. 1999. Production of high quality potato plantlets by autotrophic culture for aeroponics systems. J. Korean Soc. Hort. Sci. 123: 330-333.

Nugali Yadde M.M., De Silva H.D.M., Perera, R., Ariyaratna D., Sangakkara U.R. 2005. An aeroponic system for the production of pre-basic seed potato. Ann. Sri Lanka Department Agric. 7: 199-288.

Otazú V. 2010. Manual on quality seed potato production using aeroponics. International Potato Center (CIP), Lima, Peru. 44 p. ISBN 978-92-9060-392-4. Produced by the CIP Communication and Public Awareness Department (CPAD)

Went F.W. 1957. The experiment control of plant growth. New York.

Developing aflasafeTM

Joseph Atehnkeng, j.atehnkeng@cgiar.org, Joao Augusto, Peter J. Cotty, and Ranajit Bandyopadhyay

Aflatoxins are secondary metabolites mainly produced by fungi known as Aspergillus flavus, A. parasiticus, and A. nomius. They are particularly important because of their effects on human health and agricultural trade. Aflatoxins cause liver cancer, suppress the immune system, and retard growth and development of children. Aflatoxin-contaminated feed and food causes a decrease in productivity in humans and animals and sometimes death. Maize and groundnut are particularly susceptible to aflatoxin accumulation, but other crops such as oilseeds, cassava, yam, rice, among others, can be affected as well. Aflatoxin accumulation in crops can lower income of farmers as they may not sell or negotiate better prices for their produce. Because of the high occurrence of aflatoxin in crops, many countries have set standards for acceptable aflatoxin limits in products that are meant for human and animal consumption.

Natural populations of A. flavus consist of toxigenic strains that produce variable amounts of aflatoxin and atoxigenic strains that lack the capability to produce aflatoxin. Carefully selected and widely distributed atoxigenic strains are applied on soil during crop growth to outcompete and exclude toxigenic strains from colonizing the crop. The biocontrol technology has been used extensively in the USA with two products AF36 and afla guard® available commercially. In Africa, aflasafeTM was first developed by IITA in partnership with the United States Department of Agriculture – Agricultural Research Service (USDA-ARS) and the African Agriculture Technology Foundation (AATF). It is currently at different stages of development, adoption, and commercialization in at least nine African countries. Multiyear efficacy trials in farmers’ fields in Nigeria have showed reduced aflatoxin concentration by more than 80%.

Survey to collect and dispatch samples
Product development begins with the collection of crop samples in farmers’ stores across different agroecological zones in each country. Samples collected are mainly maize and groundnut because they are the most susceptible to aflatoxin accumulation at crop maturity, during processing, and storage. Soil samples are collected from fields where these crops were grown to determine the relationship between the Aspergillus composition in the soil and the relative aflatoxin concentration in the crop at maturity.

Import and export permits are required if crop and soil samples are shipped outside a country. The crop samples are analyzed for aflatoxin to obtain baseline information on aflatoxin levels in the region/country and the relative exposure of the population to unacceptable limits of aflatoxin.

Isolation and characterization of Aspergillus species
Aspergillus species are isolated from the crop samples to identify the non-aflatoxin-producing species of A. flavus for further characterization as biocontrol agents. The isolates are identified and grouped into L-strains of A. flavus, SBG, A. parasiticus, and further characterized for their ability to produce aflatoxin by growing them on aflatoxin-free maize grain. Aflatoxin is extracted from the colonized grain using standard protocols to determine isolates that produce aflatoxin (toxigenic) and those that do not produce aflatoxin (atoxigenic). The amount of aflatoxin produced by toxigenic strains is usually quantified to determine the most toxigenic strains that will be useful for competition with atoxigenic strains.

Understanding genetic and molecular diversity
The genetic diversity of the atoxigenic strains is also determined molecularly by examining the presence or absence of the genes responsible for aflatoxin production in each strain. The absence of these genes explains why potential biocontrol isolates would not produce aflatoxin after release into the environment. Amplification of any given marker is taken to mean that the area around that marker is relatively intact, although substitutions and small indels outside the primer binding site may not be detected. Non-amplification could result from deletion of that area, an insertion between the primers that would result in a product too long to amplify by polymerase chain reaction (PCR), or mutations in the priming sites. Non-amplification of adjacent markers is probably best explained by very large deletions.

Identification of vegetative compatible groups
Vegetative compatible group (VCG) is a technique used to determine whether the highly competitive atoxigenic isolates are genetically related to each other. In nature A. flavus species that are genetically related belong to the same VCG or family; those that do not exchange genetic material belong to different VCGs. This is an important criterion for selecting a good biocontrol agent to ensure that the selected biocontrol strains do not “intermate” with aflatoxin-producing strains after field application. With this technique, the distribution of a particular VCG within a country or region is also determined. A VCG that is widely distributed is likely to be a good biocontrol agent because it has the innate ability to survive over years and across different agroecologies. On the contrary, atoxigenic VCGs that have aflatoxin-producing members within the VCG are rejected; atoxigenic VCGs that are restricted to a few locations may also not be selected.

Initial selection of competitive atoxigenic strains
The in-vitro test determines the competitive ability of the atoxigenic isolate to exclude the toxigenic isolate on the same substrate. The competition test is conducted in the laboratory by co-inoculating the most toxigenic isolate with atoxigenic strains on aflatoxin-free maize grains or groundnut kernels. Grains/kernels inoculated with the toxigenic strain or not inoculated at all serve as controls. After incubation and aflatoxin analysis, atoxigenic isolates that reduce aflatoxin by more than 80% in the co-inoculated treatments are selected for unique vegetative compatible grouping.

Selection of candidate atoxigenic strains and multiplication of inocula
aflasafe™ is composed of a mixture of four atoxigenic strains of A. flavus previously selected from crop samples. To select the four aflasafe strains, initially 8-12 elite strains belonging to atoxigenic VCGs are evaluated in large farmers’ fields. Two or three strain mixtures, each with 4-5 elite strains, are released in separate fields by broadcasting at the rate of 10 kg/ha in maize and groundnut at about 30-40 days after planting. The atoxigenic strains colonize organic matter and other plant residues in the soil in place of the aflatoxin-producing strains. Spores of the atoxigenic strains are carried by air and insects from the soil surface to the crop thereby displacing the aflatoxin-producing strains. The four best strains to constitute aflasafeTM are selected based on their ability to exclude and outcompete the toxin-producing isolates in the soil and grain, move from the soil to colonize the maize grains or groundnut kernels in the field, and occur widely and survive longer in the soil across many agroecological zones. The use of strain mixture in aflasafe™ is likely to enhance the stability of the product as more effective atoxigenic strains replace the less effective ones in specific environments. The long-term effect is the replacement of the toxigenic strains with the atoxigenic VCGs over years.

Assessing relative efficacy of aflasafeâ„¢
Field deployment to test efficacy of aflasafeâ„¢ is carried out in collaboration with national partners and most often with the extension services of the Ministry of Agriculture. Awareness is created by organizing seminars with extension agents and farmers. During the meetings presentations are made on the implication of aflatoxin on health and trade thereby increasing their knowledge on the impact of aflatoxins. aflasafeâ„¢ is then introduced as a product that prevents contamination and protects the grains before they are harvested and during storage. Efficacy trials are carried out in fields of farmers who voluntarily agree to test the product. Field demonstrations on the use of aflasafeTM are supervised and managed by the extension agents and farmers. Farmers are trained not only on the biocontrol technology but also on other management practices that enhance better crop quality.

Farmers are also educated on the need to group themselves into cooperatives, aggregate the aflasafeâ„¢-treated grains to find a premium market with companies that value good quality products. Market linkage seminars and workshops are organized between aflasafeâ„¢ farmers, poultry farmers, and the industries to ensure that the farmers get a premium for producing good quality grains and the industries get value for using good quality raw materials for their products.

Cocoa and REDD

James Gockowski, j.gockowski@cgiar.org, Valentina Robiglio, Sander Muilerman, Nana Fredua Agyeman, and Richard Asare

Smallholder farmers produce improved cocoa planting materials, Côte d'Ivoire. Photo by IITA
Smallholder farmers produce improved cocoa planting materials, Côte d'Ivoire. Photo by IITA

In the humid lowlands of Africa, the expansion of extensive low-input agriculture is the most important driver of tropical deforestation and forest degradation with a negative impact on biodiversity and climate change (Norris et al. 2010; Phalan et al. 2011).

A recent global analysis of the climate change impact of agriculture estimated that between 8.64 and 15.1 million square km of land were spared from the plow as a result of yield gains achieved since 1961 (Burney et al. 2010). These land savings generated avoided greenhouse gas (GHG) emissions representing between 18% and 34% of the total 478 GtC emitted by humans between 1850 and 2005. A similar land use change analysis conducted for West Africa estimated that over 21,000 km2 of deforestation/forest degradation that occurred between 1988 and 2007 could have been avoided if the improved seeds/fertilizer already developed in the 1960s had been adopted (Gockowski and Sonwa 2011).

A methodology for quantifying and qualifying the impact of agricultural intensification on deforestation and poverty has been developed. This is based upon (a) the remote sensing analysis of land use change, (b) structured interviews with a random sample of rural households, and (c) an anthropological case study, all conducted in a defined benchmark area. The 1201 square km benchmark in the Bia district, Ghana, is the most important cocoa-growing area in the country whose increasingly diminished forests are home to the endangered Roloway monkey and are a global conservation priority. Cocoa producers in this benchmark have experienced rapid yield gains as a result of a sequential series of intensification policies that began in 2003.

Figure 1. Land-use change trajectories, 2000-2011.
Figure 1. Land-use change trajectories, 2000-2011.

Measuring deforestation and land use intensification
The retrospective household survey chronicled the land-use and migration history of each household in establishing a mean rate of deforestation from 1960 to 2003. More recent estimates were determined from the interpretation of satellite imagery from 2003 Landsat, 2006 Spot, and 2011 ALOS. Based on these analyses, the mean average rate of deforestation has fallen from 1,006 ha/year prior to the initiation of intensification policies to 212 ha/year.

Most of the deforestation still occurring has entailed encroachments in the Bia Game Reserve and the Krokosua Hills Forest Reserve and, to a lesser degree, Bia National Park whose environs are more stringently protected (Fig. 1). Outside these reserves there is scarcely any forest remaining.

The intensification policies initiated in the early 2000s focused on the acquisition and distribution of subsidized fertilizers and pesticides to farmers. The impact of these policies on yields and incomes was evaluated by comparing predicted outputs at 2000 and 2011 levels of input use with a micro-econometric model of household cocoa production constructed with data from the household survey (Table 1). Yields in the benchmark nearly tripled mainly because of the increased use of fertilizers and household income doubled (Gockowski et al. 2011).

Table 1. A comparison of mean input use in 2000-01 prior to fertilizer interventions and in 2010-11.
Table 1. A comparison of mean input use in 2000-01 prior to fertilizer interventions and in 2010-11.

Supporting smallholder fertilizer use instead of forests through REDD
The objective of Reducing Emissions from Deforestation and Forest Degradation (REDD) is to reduce GHG. The method is designed to use market valuation and financial incentives to reward deforestation agents, such as the cocoa farmers of Ghana, for a reduction in emissions.

To produce the output achieved in the benchmark area of our study using the extensive cocoa technology of 10 years ago would require an additional 150,000 ha of rainforest. The amount and value of carbon not entering our atmosphere because of avoided deforestation are an external value that is not captured in the market price received by the farmers intensifying production. Consequently there will be a socially suboptimal level of investment in intensification. REDD is envisaged as a mechanism for addressing this market failure.

Outlook
Fertilizer use in Africa is the lowest of any region in the world. Not only does this perpetuate poverty it also contributes to emissions of GHG and loss of biodiversity. We have developed a methodology for determining the amount of deforestation avoided through increased use of fertilizer. Thus, it is a relatively simple matter to value the emissions that are also avoided. More difficult is the question of how to distribute these resources so as to correct this perceived market failure. Directly paying farmers for environmental services has proven to be a costly endeavor and has rarely been successful with smallholders.

Cocoa plants and pods, Ghana. Photo by IITA
Cocoa plants and pods, Ghana. Photo by IITA

As an alternative we propose a government-to-government transfer of earmarked funds for supporting agricultural intensification through investments in improved public infrastructure, extension services, agricultural research, and, yes, fertilizer subsidies. There is a risk that more productive technologies lead to greater deforestation, at least at the local level. To address this, a portion of the REDD funds should be used to enforce protected forest boundaries from encroachment. When properly implemented, agricultural intensification can relieve poverty, conserve biodiversity, and reduce emissions of GHG.

References
Burney, J.A., S.J. Davis, and D.B. Lobell. 2010. Greenhouse gas mitigation by agricultural intensification. Proceedings of the National Academy of Sciences 107(26): 12052–12057.
Gockowski, J. and D. Sonwa. 2011. Cocoa Intensification Scenarios and their Predicted Impact on CO2 Emissions, Biodiversity Conservation, and Rural Livelihoods in the Guinea Rain Forest of West Africa. Environmental Management 48(2): 307–321.
Gockowski, J., V. Robiglio, S. Muilerman, and N.F. Agyeman. 2011. Agricultural Intensification as a Strategy for Climate Mitigation in Ghana: An evaluative study of the COCOBOD High Tech Program, rural incomes, and forest resources in the Bia (Juaboso) District of Ghana. Final report to CGIAR Challenge Program on Climate Change, Agriculture and Food Security (CCAFS)—Poverty Alleviation through Climate Change Mitigation.
Norris K., A. Asase, B. Collen, J. Gockowski, J. Mason, B. Phalan, and A. Wade. 2010. Biodiversity in a forest-agricultural mosaic—the changing face of West African rainforests. Biological Conservation 143: 2341–2350.
Phalan, B, M. Onial, A. Balmford, and R. Green. 2011. Reconciling Food Production and Biodiversity Conservation: Land Sharing and Land Sparing Compared. Science 333: 1289.

Afla-ELISA: A test for the estimation of aflatoxins

Lava Kumar (L.kumar@cgiar.org) and R. Bandyopadhyay
L. Kumar, IITA’s Head of Germplasm Health Unit and Virologist; R. Bandyopadhyay, Plant Pathologist, IITA, Ibadan, Nigeria

Aflatoxin testing using Afla-ELISA. Source: L. Kumar.
Aflatoxin testing using Afla-ELISA. Source: L. Kumar.
Aflatoxins threaten human and animal health
Aflatoxins are the hepatotoxic and carcinogenic secondary metabolites produced by Aspergillus flavus and A. prasiticus. They are common contaminants in several staple crops, such as maize and groundnut, produced in the tropics and subtropics. Aflatoxins are a group of four toxins: aflatoxin B1 (AFB1), AFB2, AFG1, and AFG2. A metabolite of aflatoxins, namely AFM1, is detected in milk. Aflatoxin contamination in foods is considered to be unavoidable, as the causative fungi are ubiquitous in the tropical parts of the world. However, fungal infestation and toxin contamination are unpredictable and depend on certain environmental conditions. Aflatoxin exposure in humans and animals results from the consumption of aflatoxin-contaminated foods and feeds.

Regulations check aflatoxin contamination
Stringent food safety regulations are enforced in most countries to prevent use of aflatoxin-contaminated foods and feeds. These programs are executed through a monitoring process by testing all commodities for aflatoxins and rejection of those with toxin levels exceeding the tolerable limits [ranges between 2–20 parts per billion (ppb), depending on the type of toxin and country1]. Heavy infestation of fungi results in moldy products which can be physically sorted. However, aflatoxins per se are invisible and leave no visual clues of their presence in the contaminated products. Aflatoxins can be found even in commodities that show no apparent signs of fungal infestation. This situation poses a serious challenge to monitoring aflatoxin contamination, which depends on aflatoxin-monitoring tools.

Outline of Afla-ELISA testing scheme. Source: L Kumar.
Outline of Afla-ELISA testing scheme. Source: L Kumar.
Aflatoxin control relies on monitoring tools
Monitoring for aflatoxins has become integral to effective measures to control aflatoxins in foods and feeds. A variety of aflatoxin monitoring tools are available to detect and quantify aflatoxin levels2. Quantitative estimation is most critical as decisions are based on aflatoxin levels in the commodity. Products with aflatoxin levels within the permissible range are allowed in trade and those with exceeding levels are rejected1.

Despite the availability of a wide variety of diagnostic tools for monitoring aflatoxins, their use in most of the developing countries is limited by high cost, difficulties with importation, and lack of appropriate laboratory facilities and well-trained staff. Among the many types of aflatoxin-monitoring tools, antibody-based methods were proven to be relatively easy for developing countries to adopt.

Convenient option
At IITA, we developed an enzyme-linked immunosorbent assay (ELISA) named Afla-ELISA, for quantitative estimation of aflatoxins. Very high titered rabbit polyclonal antibodies for AFB1 were produced. These antibodies have an end-point titer of 1:512,000 (v/v) against 100 ng/mL AFB1-BSA standard; they are highly specific to AFB1 and also react with ABF2, AFG1, and AFG2. They were used to develop Afla-ELISA based on the principle of indirect competitive ELISA for quantitative estimation of aflatoxins. This assay has a lowest detection limit of 0.09 ng/mL, and a recovery of 98±10% in maize.

Prototype Afla-ELISA kit―a quantitative serological assay for the estimation of total aflatoxins in maize and other commodities, using 96-well microtiter plates. Up to 20 samples can be tested in each 96-well plate at a cost of US$4 per sample. Source: L Kumar.
Prototype Afla-ELISA kit―a quantitative serological assay for the estimation of total aflatoxins in maize and other commodities, using 96-well microtiter plates. Up to 20 samples can be tested in each 96-well plate at a cost of US$4 per sample. Source: L Kumar.
Afla-ELISA is simple to perform, offers sensitive detection, and is convenient for adoption in sub-Saharan Africa. This test is suitable for routine aflatoxin surveillance in crops and commodities, and offers a low-cost alternative to official monitoring methods. This test offers a sustainable solution to the problem of ever-increasing demand for monitoring programs related to food safety and trade, and has the potential to enhance aflatoxin monitoring capacity in sub-Saharan Africa. To contribute to capacity development, training workshops have been organized on monitoring for mycotoxins and application of Afla-ELISA.

References
1 FAO. 2003. Worldwide regulations for mycotoxins in food and feed. FAO Food and Nutrition Paper #81. FAO, Rome, Italy.
2 Reiter, E. et al. 2009. Mol. Nutr. Food Res. 53: 508–524.

Funding agricultural R&D and meeting the MDG target

Member countries of the Economic Community of West African States (ECOWAS) will need to significantly increase their investment in agricultural research and development (R&D) to achieve the aim of the Millennium Development Goal (MDG) of eradicating extreme hunger and poverty by 2015.

Women selling yam, Ghana. Photo by IITA.
Investment in agricultural R and D needs to be increased to ensure Africa's food supplies. Photo by IITA.

The focus on agricultural R&D stems from the fact that, for all ECOWAS countries, more than half of a 1% reduction in poverty at the national and rural levels can be attributed to the growth of the agricultural sector.

A study by the IITA-led Regional Strategic Analysis and Knowledge Support System West Africa (ReSAKSS-WA) finds that to achieve this remarkable agricultural growth, countries in this regional bloc will have to almost double their current share of agricultural spending.

On average, an agricultural funding growth rate of 18.3% is required to achieve the target 6% rate set out by the Comprehensive Africa Agriculture Development Program (CAADP). However, successful reform of public institutions could lower this share substantially, according to a report by Mbaye Yade and colleagues.

About CAADP
CAADP was initiated in 2002 by the African Union. It is a strategic framework which guides the development efforts and partnerships of African countries in the agricultural sector. It has, among others, the following objectives and principles at its core: agriculture-led growth for poverty reduction; increased funding for agriculture (10%), and at least 6% agriculture growth, all aimed at achieving MDG1 and other welfare targets; greater efficiency and consistency in the planning and execution of sector policies and programs; increased effectiveness in translating government expenditure into public goods and services; and expertise and mechanisms to measure performance against objectives regularly and transparently, and keep policies and programs on track.

ReSAKSS-WA works with ECOWAS to provide strategic analysis, knowledge management and communications, and capacity strengthening, towards achieving the aims of CAADP.

To promote monitoring and evaluation, the African Union and the New Partnership for Africa’s Development requested ReSAKSS to develop a monitoring and evaluation (M&E) framework which would guide the continent in implementing CAADP.

Working with national and international partners, ReSAKSS has since backstopped some member countries in developing their National Agricultural Investment Programs (NAIPs) with this aim in view.

Current scenario
The ReSAKSS study shows that, under current trends, expected performance in agricultural growth is projected to stabilize at around 4.4% by 2015. However, with the successful implementation of emerging national strategies for the sector, agricultural growth is expected to increase to 6.4% from 4.6% under a business-as-usual scenario. Even the CAADP target of 6% annual agricultural growth for each country is not sufficient to achieve MDG1 by 2015, except for Bénin, Burkina Faso, Cape Verde, Ghana, and Senegal. Therefore, other plans with additional efforts are projected for the other countries.

The first M&E report from ReSAKSS indicated that the average share of agriculture in the 2005–2008 period was 10% and above in Burkina Faso, Niger, Ghana, Senegal, and Mali. It was below 10% in Bénin, Gambia, Liberia, Togo, Nigeria, Sierra Leone, and Côte d’Ivoire. With regard to the planned 6% growth in agriculture, the average rate for Gambia, Nigeria, and Sierra Leone in the 2003–2007 period was 6% and above. For all other West African countries, the average was below 6%. Apart from the incidence of stunting among children, all major indicators of welfare show an overall improvement in living standards in the 2000s compared with the 1990s.

Incidence of poverty in West Africa has decreased by about 18% in the 2000s, according to a study. Photo by IITA.
Incidence of poverty in West Africa has decreased by about 18% in the 2000s, according to a study. Photo by IITA.

The incidence of poverty using the international threshold for comparison—the US$1/person/day—decreased by 18% in the 2000s compared with the 1990s. Per capita gross domestic product (GDP) increased by 35% between 1990 and 2008. The Global Hunger Index shows a 14% decrease from the 1990–2009 value. Overall, it seems that recent trends in welfare have been positive in West Africa.

What the future holds
Regional Agricultural Investment Programs (RAIP) under CAADP are being prepared and will be funded through various mechanisms. IITA should work closely with the regional economic communities or RECs in preparing such programs because of the Institute’s wealth of experience in R4D work aimed at increasing agricultural productivity in Africa, in particular with ECOWAS in priority crops, such as cassava, maize, and rice. Already some discussions are taking place but these should be increased. Given the poverty challenges facing West Africa and Africa in general, all avenues for productive collaboration should be explored.

To implement the Africa-wide M&E system, the system has to be adapted in each West African country. Two requirements for this are the establishment of a SAKSS in each country, and consequently, the inclusion of the M&E indicators in the SAKSS and country’s annual reports and surveys.

This would make M&E a routine and important activity carried out annually. In turn, this would provide each country with the opportunity to ascertain how much progress is being made and to change the aspects of a strategy that are not working in a timely manner.

Outcome mapping: a tool for monitoring and evaluation

E.A. Ouma, e.a.ouma@cgiar.org and G.A. Neba, george.akwahneba@iucn.org

IITAroutinely measures impact resulting from its R4D projects and programs. Photo by IITA.
IITA routinely measures impact resulting from its R4D projects and programs. Photo by IITA.

Many development practitioners are preoccupied with the identification and measurement of impact resulting from their research-for-development projects or programs. In many high-level meetings, the importance of results-based management that is goal-oriented and that emphasizes cause and effect of inputs, outputs, and impacts, has been emphasized and a large number of methodological guidelines have been developed.

One such guideline is the Logical Framework Approach (LFA). It is a hierarchical linear causal-effect chain presented at four levels (activities, outputs, outcomes, and impact). It is concrete and encourages the clear formulation of outcomes and goals/impact and the precise definition of quantifiable targets. Its major weakness is the attribution of cause and effect between the levels of outcome and impact (Jones 2006). In reality, this cannot be conclusively determined. Most impacts occur a long way downstream and may not be directly influenced by a single actor. In addition, the linear cause–effect thinking in LFA is a rather strong assumption and has been criticized by many practitioners.

The weaknesses in the existing tools, particularly in the monitoring and evaluation of developmental impacts, motivated the International Development Research Centre to develop a different approach, referred to as outcome mapping.

Figure 1. Boundary partner's link to the program and the real world.
Figure 1. Boundary partner's link to the program and the real world.

Outcome mapping
Outcome mapping is a method for planning and assessing the social effects and internal performance of projects, programs, and organizations (Earl et al. 2001). It helps a project or program team to be specific about its targets, the changes it expects to see, and the strategies it employs, and as a result, to be more effective in terms of the results it achieves. Results are measured in terms of changes in the behaviors of people, groups, and organizations, also known as “boundary partners” (Fig. 1) with which a project/program works directly. The project/program works with the boundary partners to effect a change but it does not control them.

The changes are referred to as outcomes. In so doing, outcome mapping clears away many of the myths about measuring impact and focuses more on social changes within complex and dynamic partnerships. Once boundary partners have been identified, outcome mapping differentiates the levels of behavioral change which may be seen among the partner organizations—known as progress markers. These are grouped according to expected behaviors (early positive responses), desired behaviors (active engagement), and hoped-for behaviors (deep transformation in behavior) (Shaxson and Clench 2011). In the vocabulary of outcome mapping, these are behaviors we would ‘expect to see”, “like to see”, and “love to see” and they may be priorities for change or a time sequence of activities, or a mixture of both (Fig. 2).

Figure 2. Progress markers of a boundary partner. Source: Jones 2006.
Figure 2. Progress markers of a boundary partner. Source: Jones 2006.

Attribution and measurement of downstream results are dealt with through a more direct focus on transformations in the actions of the main actors. The outcomes enhance the possibilities of developmental impacts but the relationship is not necessarily a direct one of cause and effect. The outcomes can be logically linked to a project’s activities although they are not necessarily directly caused by them. Outcome mapping, therefore, focuses on the contribution of a project in the achievement of outcomes rather than claiming the achievement of developmental impacts.

The development of M&E tools (both qualitative and quantitative) for assessing outcomes and impact on commodity systems, including outcome mapping and participatory impact pathway, was identified as an output target for IITA’s Opportunities and Threats Program in 2011 (IITA 2009). This highlights the importance of developing tools not only for documenting technology adoption trends and impact but also those that monitor outcomes, providing stakeholders with timely information about their progress and achievements for systematic and collective learning, reflection, and corrective action.

A few R4D projects at IITA have employed outcome mapping or some of its elements in their M&E framework. For instance, the Consortium for Improving Agriculture-based Livelihood in Central Africa project, largely operating in the East and Central African highlands, follows the spirit of outcome mapping in its arrangements to scale out technology. The boundary partners, comprising international and national NGOs and farmers’ associations, articulate their goals, expectations, and contributions through informal or formal memoranda of agreement with the project. The project endeavors to meet the partners’ expectations through jointly planned activities to achieve the expected outcomes, which have prospects of producing sustainable impacts.
Opportunities for interactions between a boundary partner and the project and among the boundary partners are made available for collective learning, to evaluate progress towards the achievement of goals over time, and to identify corrective measures.

Other CGIAR centers, particularly the International Center for Tropical Agriculture (CIAT), International Livestock Research Institute (ILRI), and the World Agroforestry Centre, apply outcome mapping in their natural resource management and livestock projects.

Stages of outcome mapping and monitoring tools
The process is divided into three stages. The first, referred to as the intentional design phase, is largely a planning stage. This helps a project to establish a consensus on the macro-level changes it will help to bring about and to plan the strategies it will use. It is based on the principle of participation and purposefully includes those implementing the project in the design and data collection so as to encourage ownership and use of the findings. It involves articulation of the vision and mission of the project, the identification of the boundary partners, the outcome challenges, progress markers, and strategies to be employed for changing the behavior of boundary partners to better deliver the progress markers. Supportive strategies facilitate change, possibly by one partner providing information, capacity, or skills to others.

The second stage is outcome and performance monitoring. It provides a framework for an ongoing monitoring of the projects’ actions and the boundary partners’ progress toward the achievement of outcomes. It is largely based on a systematized self-assessment and uses monitoring tools for elements identified in the design stage. The tools include an outcome journal (for monitoring progress markers), a strategy journal (for monitoring the strategy maps) and a performance journal (for monitoring the organizational practices).

The third stage is evaluation planning. It helps the project to identify evaluation priorities and develop an evaluation plan (this targets priority areas for detailed evaluation studies).

Strengths and weaknesses
Outcome mapping provides a focus on institutional transformation that is often lacking in techniques which emphasize the delivery of outputs as an indicator of achievement. It aligns itself with the realities of development, often occurring in complex and open systems with multiple actors. The methodology ensures the clear formulation of responsibilities, roles, and progress markers for each project partner in addition to providing a framework and the tools for continuous monitoring. Measurable outcomes and clear milestones enhance ownership by the local actors and beneficiaries as well as the management of multiple accountabilities (project, beneficiaries, partners, and donors).

Outcome mapping’s one-dimensional focus on “changes in behavior”, although important to sustainable development, cannot be an end in itself for development. The behavioral changes should support improvements in situations at a higher level. There is a need to have clear hypotheses about the framework, tools, and indicators for impact at the level of development results (such as the MDGs). Roduner et al. (2008) have proposed a synthesized model combining the strengths of outcome mapping focusing on capacity building and the logical framework with its focus on development results. The synthesized model has, however, not yet been tested.

References
Earl S, T Smutylo, and F Carden. 2001. Outcome mapping: Building learning and reflection into development programs. IDRC, Ottawa, Canada.

Jones H. 2006. Making outcome mapping work. Evolving Experiences from Around the World. IDRC, Ottawa, Canada. http://bit.ly/19zzsH.

Roduner D, W Schläppi, and W Egli. 2008. Logical Framework Approach and Outcome Mapping: A Constructive Attempt of Synthesis. A Discussion Paper, ETH, Zurich, Switzerland.

Shaxson L, and B Clench. 2011. Outcome mapping and social frameworks: tools for designing, delivering and monitoring policy via distributed partnerships. Delta Partnership working paper No 1, www.deltapartnership.com.

DEWN: a novel surveillance system

Innocent Ndyetabula*, indyetabura@yahoo.com and James Legg, j.legg@cgiar.org
*Maruku Agricultural Research Institute, PO Box 127, Bukoba, Tanzania

Researchers inspect cassava plants for disease incidence. Photo by IITA.
Researchers inspect cassava plants for disease incidence. Photo by IITA.

Pandemics of cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) are the most important biotic constraints to cassava production in East and Central Africa.

For several years, researchers have tracked these two diseases and monitored patterns of pandemic expansion. However, costs have been high, and the visits made once a year have barely kept pace with the rate of disease spread.

Hence, researchers working to control these problems resolved to explore other monitoring options. During early discussions, two themes were frequently highlighted: community participation and new technology. Could both of these be incorporated into an alternative approach to monitoring disease spread in such a way that the system would provide an early warning of new outbreaks?

The result was the Digital Early Warning Network or DEWN. After extensive consultation, a plan was developed for its pilot-level implementation. This system works with six farmers’ groups in each of 10 disease-threatened districts of northwestern Tanzania, and provides them with a system based on the use of the mobile phone for reporting incidences of CMD and CBSD in their farms. By communicating monthly with farmers’ groups, it was expected that new outbreaks would be identified quickly, allowing the timely implementation of control measures.

Partnerships
The pilot phase of DEWN has been primarily implemented by the Lake Zone Agricultural Research Institute (LZARDI), under the IITA-coordinated Disease Objective of the Great Lakes Cassava Initiative (GLCI). GLCI is funded by the Bill and Melinda Gates Foundation (BMGF) and is led by the Catholic Relief Services (CRS). The partners of GLCI in the DEWN target districts included several local NGOs (TAHEA, MRHP, KUMKUMAKA, RUDDO, and TCRS) as well as the local government agricultural advisory system.

Training
At the outset, it was essential to train all participating farmers’ groups to recognize the symptoms of the two virus diseases, and introduce the SMS-based communication system. A total of 1281 farmers were trained in the 60 groups, and district partners were provided with a GPS unit and digital camera to record field locations and any unusual disease symptoms.

Each of the farmers’ groups was provided with a basic GSM phone and SIM card and introduced to the simple texting system for sending monthly disease reports. A straightforward text format was used for the farmers’ groups to provide information on how many farmers had observed each of the two diseases in their fields that month, and for how many farmers each disease had become more severe, less severe, or stayed the same. Once reports had been compiled at the farmers’ group level, they were sent as a single text to the LZARDI modem.

Outcomes
Validation visit. A follow-up visit was made after 6 months to validate farmers’ reports. A refresher course was provided, but the farmers generally indicated a good knowledge of the main symptoms of both diseases. Partly as a consequence of their new understanding of the significance of CMD and CBSD, there was a strong demand from participating farmers for improved varieties.

Voice of the Farmer reports. Participating farmers were linked to the Voice of the Farmer project (VOF). This is a project that is executed by Synovate and financed by BMGF. It aims to use a network of call centers to provide monitoring and evaluation support to existing BMGF programs.

Map based on farmers and researchers' report of CMD occurrence in Lake Zone districts of Tanzania.
Map based on farmers and researchers' report of CMD occurrence in Lake Zone districts of Tanzania.

DEWN provided a means for VOF to communicate directly with many of the participating farmers. This enabled VOF to conduct two surveys to assess the effectiveness of DEWN’s training program on the identification and management of cassava pests and diseases. Participating farmers were called directly by VOF call center staff and were asked a series of short questions in Swahili. Although farmers’ responses indicated a good general knowledge of CMD and CBSD, some confusion about symptoms was evident, highlighting the need for further training support. The VOF–DEWN reports are available online at www.vof.synovate.co.ke.

Mapping new disease outbreaks. Information obtained from the DEWN reports received from farmers’ groups was used to generate maps. One of the most significant findings was that CBSD, reported by farmers via SMS, was then confirmed by researchers’ visits in two districts (Bukombe and Urambo) in which CBSD had not previously been reported. This has allowed project teams to focus extra disease mitigation efforts on these areas.

Extending DEWN. Recognizing the potential value of DEWN for providing communities with a means of doing their own monitoring of crop disease, the GLCI cassava team in Rwanda decided to start a similar scheme. Farmers’ representatives from Rwanda visited DEWN partners in Tanzania in October 2010 and were introduced to the approach and given training in recognizing CBSD and CMD. The Rwanda team will initiate its own DEWN program in 2011.

Map based on farmers and researchers' report of CBSD occurrence in Lake Zone districts of Tanzania.
Map based on farmers and researchers' report of CBSD occurrence in Lake Zone districts of Tanzania.

DEWN has provided an innovative, informative, and relatively cheap means for involving communities in monitoring the health of their own crops. Farmers’ participation has been enthusiastic, and some important practical outcomes have been achieved. Two of the greatest challenges which remain, however, are the accurate diagnosis of CBSD, which has cryptic or unrecognized symptoms and the regular provision of feedback to participating communities.

Plans are already being developed to address these problems. As these difficulties are overcome and as connectivity in rural areas continues to expand, it seems certain that there is great potential for the more widespread use of digital networks such as DEWN for the community-based monitoring of crop diseases.

Conserving cowpea using GIS tools

Diversity of cowpea seeds. Photo by IITA.
Diversity of cowpea seeds. Photo by IITA.

The germplasm collections in genebanks are an invaluable resource for the future. The conservation of this biodiversity is tied to agricultural production and represents a safety net for the food security of future generations.

In addition to the conservation, multiplication, regeneration, and characterization of these collections, another central function of a genebank is the expansion of germplasm collections to cover as much agrobiodiversity as possible.

IITA works on cowpea improvement and holds the largest cowpea germplasm collection in the world (15,115 accessions); 10,814 (71.5%) of these were collected in Africa or acquired from African national programs.

High protein food legume
The cowpea is a very important, widely adapted, and versatile grain legume of high nutritional value. It is mainly produced and consumed in Africa where it provides a major low-cost dietary protein for millions of smallholder farmers and consumers who cannot afford high protein foods, such as fish and meat. Food legumes, particularly cowpea, have high protein contents. Cowpea contains 24% protein, 62% soluble carbohydrates, and small amounts of other nutrients.

It is a very low-input crop, traditionally grown in intercropping systems. Cowpea contributes to soil fertility through nitrogen fixation and is also cultivated to prevent soil erosion.

The worldwide area cultivated with cowpea in 2008 was estimated to be 11.8 million ha with an annual production of 5.4 million t of dried grains (FAOSTAT 2010).

Production in Africa represents about 91% of the global production. West Africa, with 10.7 million ha, accounts for most of Africa’s production, with Nigeria and Niger being the leading cowpea growing countries (FAOSTAT 2008). The area planted with cowpea is substantial in Senegal, Mauritania, Mali, Burkina Faso, Côte d’Ivoire, Ghana, Bénin, Togo, Chad, Cameroon, Central African Republic, Congo, Uganda, Tanzania, Sudan, Ethiopia, Kenya, Angola, Somalia, Zambia, Mozambique, Zimbabwe, Botswana, Namibia, South Africa, and Madagascar (NRC 2006).

Ex situ conservation in IITA genebank: long-term storage, −20 °C. Photo by IITA.
Ex situ conservation in IITA genebank: long-term storage, −20 °C. Photo by IITA.

Cowpea diversity
At IITA, cowpea is maintained in two storage conditions, medium (5°C) and long-term (-20°C) at an optimal water content of 7−8% fresh weight basis. The viability of most accessions stored at –20°C for 25 years remains as high as 90%.

To avoid losses of genetic diversity and to guide future sampling, researcher Anne Rysavy of the University of Hohenheim (now with the University of Tuebingen), GIS Specialist Kai Sonder (now with CIMMYT), and the head of IITA’s Genetic Resources Center, Dominique Dumet, assessed the geographic coverage of the current collection to get an overview of the crop’s conservation status. The study identified areas in Africa where the probability of finding more and diverse Vigna unguiculata accessions is highest and where further collection should be done.

GIS tools
Gap analysis is an evaluation technique applied to provide wide geographic information on the status of different species and their habitats using satellite data and different computer tools and by digital map overlays in a geographic information system (GIS). Gaps refer to geographical areas that are underrepresented in the collection and where cowpea is expected to occur based on agrometeorological and other factors.

GIS can be a powerful tool for analyzing spatial distribution of a species. Combined with biophysical information from germplasm collections, it can help in conducting surveys and prioritizing future sampling areas. Areas that have not yet been sampled can be targeted for collecting missions so that the material can be conserved ex situ or using in situ conservation strategies.

Specifically, the study analyzed, corrected, and georeferenced the available passport data for cowpea. It also applied different GIS tools to identify gaps in previous collection areas, and predicted areas where new diversity is likely to be collected and/or areas where diversity erosion risk is highest, e.g., from climate change, civil war, deforestation, etc.

This study used spatial analysis tools and software applications, such as FloraMapTM, HomologueTM, ArcGISTM, and DIVA-GIS, including the predictive models EcoCrop, BIOCLIM, and DOMAIN to perform the gap analysis on the existing cowpea germplasm collection at IITA and identify potential areas for future conservation activities.

First the country coverage of georeferenced cowpea accessions was determined. Then, ecogeographical site descriptors (temperature, precipitation, length of growing period, and altitude) were extracted to determine areas with environmental conditions favorable to cowpea. Based on this, regions with similar environmental conditions were identified using GIS techniques.

Distribution of the 10,814 cowpea accessions
Distribution of the 10,814 cowpea accessions

Gaps in cowpea collection
Study results provide an overview of the actual distribution, agroclimatic preferences, and potential distribution of cowpea.

The geographical scope of the study focused on sub-Saharan Africa. Results indicated that cowpea can be found approximately between 15°N and 20°S, and over a large range of climates—temperature as well as precipitation. However, it occurs most likely in subtropical to tropical conditions characterized by warm temperatures (annual average >20°C) and relatively high annual precipitation (>250 mm).

The distribution of the total number of cowpea accessions held in the IITA genebank is very diverse with a certain concentration in West Africa (see map). Nigeria and Niger account for nearly 50% of all accessions. The origins of the remaining 50% are unequally distributed across the continent. Several countries such as Burundi, Equatorial-Guinea, Eritrea, Guinea-Bissau, Namibia, and Rwanda are not represented.

Depending on the country, the total number of accessions collected within Africa ranged between one (Algeria and Angola) and 3,813 (Nigeria). Nigeria ranked first with 35.3% and Niger second with 11.6% (1,249 accessions).

Cameroon, Botswana, and Zambia accounted for 15% of the total number of accessions, each contributing 5%. Tanzania, Malawi, Bénin, Egypt, Ghana, Mali, Burkina Faso, and Senegal accounted for 24.4%.

All the methodologies used identified areas where, according to agroecological similarities, the probability is high of finding more cowpea accessions and no collections have been carried out yet, or very few accessions have been collected. They proved to be useful approaches to conserving the genetic diversity of crop species.

Based on the predictive models, the following countries were identified as the priority for the acquisition of new germplasm: Angola, Burundi, Guinea-Bissau, Eritrea, Equatorial-Guinea, Namibia and Rwanda, especially since no collections have yet been made in these countries. In addition, further sampling is recommended in countries with small numbers of georeferenced accessions, such as Botswana, Congo, DRC, Gambia, Lesotho, Liberia, Madagascar, Sierra Leone, Sudan, Swaziland, and Uganda.

Germplasm acquisition will be done through the duplication of existing national collections at IITA with the support of the Global Crop Diversity Trust (GCDT), and specific collecting missions to capture missing diversity. The GCDT has commissioned IITA to lead the development of a global conservation strategy for the genetic resources of cowpea and its wild relatives with an emphasis on Africa.

Is mechanization the solution to cowpea’s woes?

The cowpea is one of the most important grain legumes in Africa. Cowpea is both economically and nutritiously significant. Its ability to fix nitrogen efficiently and grow in a wide range of conditions means that the cowpea is also a suitable companion for a wide range of other food and fiber crops.

Farmer beating cowpea pods to open them. Photo by IITA.
Farmer beating cowpea pods to open them. Photo by IITA.

Nigeria is the world’s largest producer of the crop, growing 45% of the global yield. However, this total amount has dropped considerably in the past 30 years, from 61% in 1981 to 45% in 2004. With cowpea playing such a key role in the agriculture and food supply of Nigeria, production and processing practices need to be improved, emphasized Thierno Diallo of IITA’s Postharvest Utilization Unit.

The production and processing begins before the seeds have even been planted. Land clearance involves cutting down trees, pulling up stumps, leveling the land, and extracting roots and stones.

Of all the agricultural operations, land clearance is the most difficult and costly. After this the soil must be properly prepared to create good conditions for the seeds to germinate and grow. This starts with the time- and energy-consuming preparation of the seed bed and includes planting and fertilizing. The plant must then be maintained for its life span. This means preventing weeds, pests, and organisms that cause diseases such as bacteria, fungi, and viruses, from severely affecting the crop, as well as keeping the cowpea irrigated if so required.

When fully mature the plants are ready to be harvested. This involves cutting the dry pods before they are attacked by birds or rodents. After this the pods must be opened to release the grains. This is done in two stages: first, the pods are beaten to open them and then they are scooped up and fanned out to separate the grains from the shells in a process called threshing. The grains are collected and dried to increase quality and shelf life, then stored.

All of these operations are traditionally done by hand or with the help of animals and are thus associated with drudgery. “The mechanization of existing tools and the promotion of efficient farm management techniques could be the way to increase Nigerian cowpea production once again,” Diallo said. Diallo had been involved in designing some processing machines now in use by small industries in Nigeria and other sub-Saharan African countries.

The advantages of mechanization have already been demonstrated with threshing. Traditionally, sticks were used to beat the grains out of the pods but they sometimes broke the seeds, rendering them useless. In the 1990s, IITA introduced a tool called the Fail-safe Flail, which prevented most of the damage to seeds. The motorized multicrop thresher further improved the process as it could do the job of several workers with flails, taking away much of the drudgery. These two devices increased the productivity of threshing. The recent introduction of a fanning system to the multicrop thresher has made it significantly better still.

Fabricating small machines for processing, IITA. Photo by IITA.
Fabricating small machines for processing, IITA. Photo by IITA.

Drying is another area where successful mechanization has been implemented. Farmers used to spread the cowpea grains on the ground to dry under the sun. The introduction of drying platforms has not only made the process more hygienic but also more flexible as it does not depend on the sun any longer. Dryers of various designs and capacities are available, from small drying shelves to medium-capacity cabinet dryers and high-capacity rotary dryers. The larger dryers use fuels such as charcoal, wood, or diesel as the source of heat. Some are equipped with a milling facility to produce flour.

By upgrading to machines such as these a farmer could not only get through the various stages of production faster but also run systems such as irrigation, uninterrupted. This in turn would cut costs and improve overall yields as well as boosting confidence and encouraging more people to grow cowpea.

Furthermore, the high cost of purchasing or renting a machine would be offset by the fact that one machine is now capable of completing many different tasks.

Thus, when it comes to producing and processing cowpea, a move to mechanization is essential to fulfill the demand for the crop in Africa and worldwide, according to Diallo.