Okra (Abelmoschus spp.) in West and Central Africa: Potential and progress on its improvement

Abstract

Okra (Abelmoschus spp.) is a traditional vegetable crop with considerable area under cultivation in Africa and Asia with huge socio-economic potential in West and Central Africa. It has been called "a perfect villager's vegetable" because of its robust nature, dietary fibers and distinct seed protein balanced in both lysine and tryptophan amino acids (unlike the proteins of cereals and pulses) it provides. However, okra has been considered a minor crop and no attention was paid to its improvement in the international research program in past. This review describes a general overview of okra's nutritional and economic potential with special reference to its past and recent progress on germplasm regeneration, genetic studies and efforts on genetic improvement in West and Central Africa.

Full text

African Journal of Agricultural Research Vol. 5(25), pp. 3590-3598, December 2010 Special Review
Available online at http://www.academicjournals.org/AJAR
ISSN 1991-637X ©2010 Academic Journals
Review
Okra (Abelmoschus spp.) in West and Central Africa:
Potential and progress on its improvement
Sanjeet Kumar1*, Sokona Dagnoko2, Adamou Haougui3, Alain Ratnadass4, Dov Pasternak5
and Christophe Kouame6
1AVRDC-The World Vegetable Center/ICRISAT Project, Niamey, Niger.
2AVRDC-The World Vegetable Center, Sub-Regional Station for West Africa, Samanko, Mali.
3 Institut National de la Recherche Agronomique du Niger (INRAN), Niamey, Niger.
4 Centre de Coopération Internationale en Recherche Agronomique pour le Développement ICRISAT, Niamey, Niger.
5International Crops Research Institute for the Semi Arid Tropics (ICRISAT), Niamey, Niger.
6AVRDC-The World Vegetable Center, Yaoundé, Cameroon.
Accepted 26 November, 2010
Okra (Abelmoschus spp.) is a traditional vegetable crop with considerable area under cultivation in
Africa and Asia with huge socio-economic potential in West and Central Africa. It has been called “a
perfect villager’s vegetable” because of its robust nature, dietary fibers and distinct seed protein
balanced in both lysine and tryptophan amino acids (unlike the proteins of cereals and pulses) it
provides. However, okra has been considered a minor crop and no attention was paid to its
improvement in the international research program in past. This review describes a general overview of
okra’s nutritional and economic potential with special reference to its past and recent progress on
germplasm regeneration, genetic studies and efforts on genetic improvement in West and Central
Africa.
Key words: Abelmoschus, genetic improvement, germplasm, okra, West and Central Africa.
INTRODUCTION
To meet demand for nutritionally balanced food for the
world’s increasing population and relieve the intense
pressure on land use and natural resources, plant
species used as food must be diversified (Hughes, 2009).
Inclusion of a wide array of indigenous vegetable species
in cereals-, tubers- and livestock-based agriculture will be
crucial to contribute to food/nutritional security and
income diversification for stakeholders in the subsistence
farming system that predominate in the underdeveloped
and developing world. Therefore, improving the genetic
potential of indigenous vegetables like okra
(Abelmoschus spp.) is of paramount importance. Okra
*Corresponding author. E-mail: sanjeet.kumar@worldveg.org,
s.kumar.avrdc@cgiar.org. Fax: 227-20734329.
has considerable area under cultivation in Africa and Asia
with huge socioeconomic potential. In West and Central
Africa (WCA), okra is called Gombo (French), Miyan-gro
(Hausa), La (Djerma), Layre (Fulani), Gan (Bambara),
Kandia (Manding), Nkruma (Akan), Fetri (Ewe) and is
among the most frequently and popularly consumed
traditional vegetables. In the African context, okra has
been called as “a perfect villager’s vegetable” because of
its robust nature, dietary fibers and distinct seed protein
balanced in both lysine and tryptophan amino acids
(unlike the proteins of cereals and pulses) it provides to
diet (NAP, 2006). However, okra has been considered a
minor crop and until recently no attention was paid to its
improvement in the international research program
(Duzyaman, 1997). This review presents a general
overview of okra’s nutritional and economic potential with
special reference to past and recent progress on its

Kumar et al. 3591
countries
0
20000
40000
60000
80000
100000
120000
Benin
Burkina Faso
Cameroon
Côte d'
Ivoire
Ghana
Senegal
2006
2007
2008
Figure 1. Okra production (tonnes) in some West Africa countries.
progress on its improvement in WCA region.
PRODUCTION STATISTICS AND CROPPING
SYSTEMS
Home to about 100 million of the world’s poorest people,
WCA has world’s most fragile ecosystem for agriculture,
yet about 80% population depend on agriculture for their
livelihoods. The WCA region accounts for more than 75%
of okra produced in Africa, but the average productivity in
region is very low (2.5 t/ha) compared to East (6.2 t/ha)
and North Africa (8.8 t/ha) (FAOSTAT, 2006). Nigeria is
the largest producer (1,039,000 t) followed by Cote
d’Ivoire, Ghana and others (Figure 1) (FAOSTAT, 2008).
In the region, okra is traditionally cultivated as a rainy
season crop by women, often on most marginalized lands
easily accessible to them. The region’s soil is low in
organic matter and land degradation is a crucial
challenge to be addressed. With the rapid urbanization
and population growth, market-oriented okra production
is increasing in peri-urban zones. Okra is now cultivated
as an irrigated crop during the dry season, where it is
often produced in mixed cropping with onion and other
crops. On the degraded land, okra has proved to be an
important rain-fed crop along with roselle (Hibiscus
sabdariffa) (Pasternak et al., 2009). A common
intercropping combination in southwest Nigeria is
maize/okra relay cropping followed by watermelon or
bush greens and jute mallow or fodder crop of sweet
potato. Okra is suitable for intercropping with papaya
(Adelana, 1986; Aiyelaagbe and Jolaoso, 1992). In the
peri-urban areas of Abidjan, year-round intensive okra
production is dominated by men, who produce and
supply up to 30% of the market demand (Kouame,
personnel communication).
DOMESTICATED SPECIES
There are four known domesticated species of
Abelmoschus. Among these, A. esculentus (common
okra) is most widely cultivated in South and East Asia,
Africa, and the southern USA. In the humid zone of WCA,
A. caillei (West African okra) with a longer production
cycle, is also cultivated (Siemonsma, 1982). Plants of A.
manihot sometimes fail to flower and this species is
extensively cultivated for leaves in Papua New Guinea
(Hamon and Sloten, 1995), Solomon Islands and other
South Pacific Islands (Keatinge, 2009). The fourth
domesticated species, namely, A. moschatus, is
cultivated for its seed, which is used for ambretee in India
and several animism practices in South Togo and Benin
(Hamon and Sloten, 1995).
TAXONOMY, CYTOLOGY AND ORIGIN
Okra was previously included in the genus Hibiscus.
Later, it was designated to Abelmoschus, which is
distinguished from the genus Hibiscus by the
characteristics of the calyx: spatulate, with five short
teeth, connate to the corolla and caduceus after flowering
(Kundu and Biswas, 1973; Terrell and Winters 1974).
Although about 50 species have been described, eight
are most widely accepted (Borssum, 1966; IBPGR,
1990). There is significant variation in the chromosome
numbers and ploidy levels in Abelmoschus. The lowest
chromosome number known is 2n = 56 for A. angulosus
(Ford, 1938) and the highest are close to 200 for A. caillei
(Siemonsma, 1982). Even within A. esculentus,
chromosome numbers 2n = 72, 108, 120, 132 and 144
are in regular series of polyploids with n = 12 (Dutta and
Naug, 1968).

3592 Afr. J. Agric. Res.
Table 1. Okra’s potential for research and contribution to enhanced livelihoods.
Criterion Potential
General knowledge Okra offers many production possibilities, however, there are limited studies
conducted on okra biology and production due to limited resources devoted to the
species by national and international research institutes.
Citation in literature Out of 100 species described in a popular vegetable textbook of Africa, only three
were important and indigenous; okra was among these three.
Indigenous and general
adaptation Early domestication took place in Africa because of its wider adaptation in the region.
Specific adaptation
(breeding) Fast maturing types would be well-suited to tropical heat, humidity and also to dry
(rain-fed) and hot (Sudano-Sahelian) conditions.
Food and nutritional
security
Pods contain high amounts of dietary fiber and they are often dried, stored, and
consumed as soup/souse much like a staple food. Half a cup of the cooked pods
(fresh) provides about 10% of the recommended levels of vitamin B6, folic acid and
vitamins A and C. The seed (usually consumed with pods) protein is distinct from
both cereals and legumes.
Market/income security Because it can easily be dried, mould (powder) and stored for long periods (unlike
perishable vegetables), producers, and processors are better able to add value and
take advantage of seasonal fluctuations in price.
Biomass for fuel
Besides pod yield, the foliage and stems can weigh up to 27 t/ha. This biomass is
likely to become useful with fuel prices increasing worldwide and new technologies
promising efficient conversion to liquid fuels. It is worth mentioning that okra stems
generate considerable heat without sparks, excessive smoke, or bad odors.
Others industrial uses The potential for non-vegetable use are: paper pulp, like its close relative kenaf, oil
seed, mucilage, sacks and ropes, bioabsorbent, medicine etc.
*Mostly synthesized from National Academies Press, 2006.
Contradicting evidence exists on the geographical
origin of A. esculentus. One putative ancestor (A.
tuberculatus) is native to Uttar Pradesh in North India,
suggesting that A. esculentus originated in India. The
other evidence is based on the plants cultivation in
ancient times, and the presence of another putative
ancestor (A. ficulneus) in East Africa, suggesting northern
Egypt or Ethiopia as the geographical origin of A.
esculentus. So far A. caillei (2n = 196 to 200) has been
located only in WCA, so this region can be recognized as
its origin and is believed to be amphipolyploids between
A. esculentus (2n = 130 to 140) and A. manihot (2n = 60
to 68).
POTENTIAL OF OKRA
Potential for enhancing livelihoods
Okra has huge potential for enhancing livelihoods in
urban and rural areas and to several stakeholders (Table
1) (NAP, 2006). It offers a possible route to prosperity for
small-scale and large-scale producers alike and all those
involved in the okra value chain, including women
producers and traders.
Nutritional potential
K, Na, Mg and Ca are the principal elements in pods,
which contain about 17% seeds. Presence of Fe, Zn, Mn
and Ni also has been reported (Moyin-Jesu, 2007). Fresh
pods are low in calories (20 per 100 g), practically no fat,
high in fiber, and have several valuable nutrients,
including about 30% of the recommended levels of
vitamin C (16 to 29 mg), 10 to 20% of folate (46 to 88 µg)
and about 5% of vitamin A (14 to 20 RAE) (NAP, 2006).
Both pod skin (mesocarp) and seeds are excellent source
of zinc (80 µg/g) (Glew, 1997; Cook et al., 2000). Okra
seed is mainly composed of oligomeric catechins (2.5
mg/g of seeds) and flavonol derivatives (3.4 mg/g of
seeds), while the mesocarp is mainly composed of

hydroxycinnamic and quercetin derivatives (0.2 and 0.3
mg/g of skins). Pods and seeds are rich in phenolic
compounds with important biological properties like
quartering derivatives, catechin oligomers and
hydroxycinnamic derivatives (Arapitsas, 2008). These
properties, along with the high content of carbohydrates,
proteins, glycol-protein, and other dietary elements
enhance the importance of this foodstuff in the human
diet (Manach et al., 2005; Arapitsas, 2008). Dried okra
sauce (pods mixed with other ingredients and regularly
consumed in West Africa) does not provide any beta
carotene (vitamin A) or retinol (Avallone et al., 2008).
However, fresh okra pods are the most important
vegetable source of viscous fiber, an important dietary
component to lower cholesterol (Kendall and Jenkins,
2004). Seven-days-old fresh okra pods have the highest
concentration of nutrients (Agbo et al., 2008).
Seed as potential edible oil and flour source
Like soybean oil, okra seed oil is rich (60 to 70%) in
unsaturated fatty acids (Crossly and Hilditech, 1951;
Savello et al., 1980; Rao, 1985). Seed protein is rich in
tryptophan (94 mg/g N) and also contains adequate
amounts of sulfur-containing amino acid (189 mg/g N) —
a rare combination that makes okra seeds exceptionally
useful in reducing human malnutrition (NAP, 2006). Okra
seed protein with good protein efficiency ratio (PER) and
net protein utilization (NPU) values is comparable to
many cereals (except wheat) and its oil yield is
comparable to most oil seed crops except oil palm and
soybean (Rao, 1985). Moreover, okra seed oil has
potential hypocholesterolemic effect (Rao et al., 1991).
The potential for wide cultivation of okra for edible oil as
well as for cake is very high (Rao, 1985). Okra seed flour
could also be used to fortify cereal flour (Adelakun et al.,
2008). For example, supplementing maize ogi with okra
meal increases protein, ash, oil and fiber content
(Akingbala et al., 2003). Okra seed flour has been used
to supplement corn flour for a very long time in countries
like Egypt to make better quality dough (Taha el-Katib,
1947). However, long-term rodent/animal feeding trials
would be pertinent before making final recommendations
for wider consumption of okra seed flour.
Mucilage and its potential
Okra mucilage refers to the thick and slimy substance
found in fresh as well as dried pods. Mucilaginous
substances are usually concentrated in the pod walls (not
in seeds) and are chemically acidic polysaccharides
associated with proteins and minerals (Woolfe et al.,
1977). Although nature of the polysaccharides varies
greatly, neutral sugars rhamnose, galactose and
galacturonic acid have been reported often (Hirose et al.,
Kumar et al. 3593
2004; Sengkhamparn et al., 2009). The okra mucilage
can be extracted as a viscous gum using various
procedures. Such diversity in the extraction procedures
seems to contribute to the observed variability in the
mucilage chemical composition (Ndjouenkeu et al.,
1996). Okra mucilage is a renewable and inexpensive
source of biodegradable material. Its physical and
chemical properties include high water solubility,
plasticity, elasticity and viscosity (BeMiller et al., 1993).
Most physical and chemical properties are influenced by
factors such as temperature, pH, sugar and salt contents,
and storage time (Woolfe et al., 1977; Baht and
Tharanathan, 1987). Okra mucilage has potential for use
as food, non-food products, and medicine. Food
applications include use as a whipping agent for
reconstituted egg whites, as an additive in the formulation
of flour-based adhesives, and as an additive in India for
clarifying sugarcane juice. Non-food applications include
brightening agents in electro deposition of metals, as a
deflocculant in paper and fabric production, and as a
protectant to reduce friction in pipe-flow (BeMiller et al.,
1993; Ndjouenkeu et al., 1996). Polysaccharides can be
combined with acrylamide to develop new biodegradable
polymeric materials (Mishra et al., 2008). Potential of
mucilage for medicinal applications includes uses as an
extender of serum albumin (BeMiller et al., 1993), as
tablet binder (Ofoefule et al., 2001) and as suspending
agent in formulations (Kumar et al., 2009). Okra mucilage
is used in Asian medicine as a protective food additive
against irritating and inflammatory gastric diseases
(Lengsfelf et al., 2004).
PAST AND PRESENT RESEARCH FOR
DEVELOPMENTAL EFFORTS
Germplasm management
The Bioversity International in collaboration with the
Institut de Recherche pour le Développement (IRD,
formerly ORSTOM) conducted okra germplasm explo-
ration in several WCA countries from 1982 to 1986. Along
with Asian and African collections, a core collection at
ORSTOM in Montpellier, France was established.
However, active collections from this core are no longer
available for the breeding use. More than 3000
collections along with collections from Asia are
maintained and distributed by National Plant Germplasm
System (NPGS), United States. Nevertheless, the West
African accessions under-represent collections from
countries like Niger (3) and Chad (5). AVRDC – The
World Vegetable Center, in collaboration with its partners,
has initiated countrywide explorations and would like to
continue exploring in un-explored regions. For instance
between 2008–2009, 102 new accessions from Mali,
Senegal, Niger and Guinea have been collected and
regenerated for public use. Varietal data collected and

3594 Afr. J. Agric. Res.
Table 2. List of selected popular okra cultivars in some of WCA countries.
Country Name of cultivar
Senegal Lolli, Indiana, POP-11 (Emerald), Volta, Lima (F
1
), PoP-12 (landrace)
Mali Yelen, Clemson Spineless, Sabalibougou, Keleya
Cote d’Ivoire Hire, Perkins Long Pod, Koto, Tomi (A. caillei)
Cameroon Clemson Spineless, Volta, Emerald; Gombo Paysan, Gombo Cafeier
Togo Konni (purified landrace), Local (A. caillei)
Ghana Indiana, Saloni (F
1
), Asontem, Torkor
Nigeria LD 88, Clemsion, Spineless, Lady’s Finger, V-35, White Velvet, Ex-Borno
Niger Konni, Terra (purified landrace), Volta
analyzed on landraces (traditional variety) and improved
cultivars used by farmers from Burkina Faso has
revealed that considerable genetic diversity in the form of
on-farm richness and community evenness is maintained
in landraces (Jarvis et al., 2008).
Genetic improvement
In countries like USA and India, a number of okra
varieties have been developed through breeding efforts.
Many of these were introduced in WCA countries and are
still popular (Table 2). There is a series of very good
reports on genetic studies in okra, especially from Nigeria
by Ariyo and associates. Multivariate analysis of 14
characters (pod yield, branch per plant, leaves per plant,
days to flowering, plant height at flowering and maturity,
pods per plant, edible pod length and width, mature pod
length, duration of flowering, life span, seeds per pod,
100 seed weight) of 30 genotypes collected from different
geographical areas revealed no relationship between
clustering pattern and geographical distribution of okra
genotypes (Ariyo, 1987). Pod yield and several yield-
contributing characters lack stability due to strong
environmental influence, suggesting the need for
breeding for specific environment (Ariyo, 1990). Diversity
in pod shape/size and flowering behavior account for
most of the variation between the genotypes of WCA
origin (Duzyaman, 1997) and scope for further gain in
pod yield per plant is limited because of low phenotypic
and genotypic variability (Ariyo, 1990). To break the yield
barrier in existing genotypes of common okra (A.
esculentus) and breed for different market types, a
hybridization-based breeding strategy would be
desirable.
Although some of the WCA national agricultural
research system (NARS) and private seed companies
have ongoing okra improvement projects, they have
never been supported through international okra
research. Despite okra’s recognized potential and
significant area and consumption in the developing world
in general and in West Africa in particular, it has been
considered an economically minor crop (Duzyaman,
1997). Commercial okra cultivation in the region
faces many challenges including photoperiod sensitivity
and cold temperatures that limit year-round availability of
fresh pods; shelf-life, fiber/mucilage content, and pest
resistance, especially root-knot nematodes, tomato fruit
worm and begomoviruses. To overcome these
challenges, a long term breeding project was warranted.
Since, 2003, AVRDC – The World Vegetable Center
and its partners, have been introducing, testing and
promoting new cultivars. Efforts are sustained through
pure line selection for high yielding cultivars with high
mucilage content. Three promising lines (Sasilon,
Batoumambe and Safi) are currently being promoted in
Mali and The Gambia. In 2007, okra improvement
activities were initiated at center’s outreach office that
execute AVRDC/ICRISAT joint vegetable breeding
project at Sadore, Niger. In the first phase, about 250
okra accessions representing collections from most parts
of the world were introduced, regenerated, and
characterized for morphological data. The regenerated
species include: common okra (A. esculentus; 175), West
African okra (A. caillei; 45) and other Albemoschus
species like A. ficulneus, A. manihot, A. manihot var.
tetraphyllus, A. moschatus and A. tuberculatus. Although
these accessions mostly represent previous collections
from WCA and South Asia, a few representative
accessions from the Middle East, USA and East Africa
were also introduced and maintained. These germplasm
lines, along with recycled inbreds derived from a popular
hybrid (Lima) in the region are available for use. As okra
has large acreage under rain-fed conditions, our breeding
goal is focused on developing okra lines for both rain-fed
and irrigated production systems. Efforts are being made
to screen germplasm against root knot nematode.
Considering the potential of West African (A. caillei) okra,
we are also developing inter-specific crosses and efforts
to overcome hybrid breakdown barriers is underway, to
facilitate pre-breeding and broadening of genetic base. A
short duration Konni variety selected from a local
population in Niger has been proven to be the “best bet”
so far; it is being mass disseminated in the Sudano-Sahel
under both rain-fed and irrigated conditions (Pasternak,et
al. 2009). Selection and cross-breeding efforts by the
Center have laid out a full-fledged okra improvement plan
for WCA with potential to expand it to Asia. However,

Kumar et al. 3595
Table 3. Potential of recombination breeding involving two Abelmoschus spp.
Species Cytogenetics Contrasting traits
A. esculentus
(common okra)
95% cultivated
area
Amphidiploid (2n=130-140):
A. tuberculatus or A.
ficulneus (2n-58-60) x
unknown?
Poor adaptation in humid zone, more susceptible to biotic stresses, less
vigorous, short life cycle (suitable for short rainy season areas), usually day
neutral, cultivated in both rainy (rain fed) and dry (irrigated) seasons
A. caillei (West
African okra)
5% cultivated
area
Amphipolyploid (2n = 196-
200): A. esculentus (2n=130-
140) x A. manihot (2n = 60-
68)
Better adaptation in humid zone, tolerant/ resistant to biotic stresses, more
vigorous, longer life cycle, mostly photoperiod sensitive, cultivated mainly in dry
season
achievements made and platforms set up so far need
follow-up to ensure significant and sustained progress.
West African okra (A. caillei) as potential donor
species
West African okra (A. caillei, also known as Guinean
type) accounts for only 5% of the total world production of
okra (Siemonsma and Kouame, 2004), but it is a very
important crop in tropical areas of Cote d’Ivoire, Benin,
Cameroon, Nigeria, Ghana and Togo. This relatively
newly identified amphipolyploid species (Siemonsma,
1982) is known for possessing a gene pool of variation
that may be useful for okra improvement of both
temperate and tropical types (Table 3) (Martin et al.,
1981). A. caillei is gradually replacing common okra in
the tropical-humid region because of its better adaptation
under humid zone and tolerance to biotic stresses
(Siemonsma, 1982). Indeed under very limited and erratic
rainfall in the Sudano-Sahel, earliness of A. esculentus
(being amphidiploid) as compared to A. caillei (being
amphipolyploid) was preferred during early
domestication. In Asia, A. caillei has been utilized as a
resistant source to breed Yellow vein mosaic virus
resistant common okra variety (Nerkar and Jambhale,
1985). The inter-specific cross between A. caillei and A.
esculentus is successful with the possibility of gene
transfer, although the partial hybrid breakdown barrier
must be overcome (Fatokun, 1987). The study on
geographical distribution and extent of natural
outcrossing in Benin and Togo suggests that genetic
integrity of these two species is not threatened (Hamon
and Hamon, 1991).
Molecular markers
Reports on marker development in okra are very scanty
and have been limited to characterization of cultivars. An
agreement between clustering patterns obtained from
morphological traits and molecular markers in
Abelmoschus spp. has been demonstrated (Mortinello et
al., 2001). Ninety-three accessions of common (A.
esculentus) and West African (A. caillei) could be
distinguished using random amplified polymorphic DNA
(RAPD) markers (Aladele et al., 2008). Use of sequence
related amplified polymorphism (SRAP) in marker aided
selection (MAS) for various traits in Turkish germplasm
has been suggested (Gulsen et al., 2007). Recently, 20
okra accessions from Burkina Faso were analyzed using
16 primers designed to amplify SSR regions of Medicago
truncatula. Two accessions were found distinct from the
other 18, based on the presence of an unique 440 bp
fragment generated primer MT-27 and also based on
presence of hairs on fruits and delayed maturity of these
two accessions (Sawadogo et al., 2009).
Biotic stresses
Although okra is considered a robust crop, under large-
scale commercial production, yield losses are very high
due to the incidence of a number of biotic and abiotic
stresses. The most relevant biotic stress of okra is the
leaf curl disease caused by the begomovirus (Okra leaf
curl virus, OLCV) transmitted by the white fly (Bemisia
tabaci). OLCV disease has been found to be more
prevalent in the savannah area than in the tropical-forest
region (N’Guessan et al., 1992). This viral disease is
followed by root-knot nematodes (Meloidogyne spp.)
which are major production hurdles, not only in the WCA
but also in Middle-East Asia (Fauquet and Thouvenel,
1987; Atiri and Fayoyin 1989). Serious efforts to screen
germplasm for viral resistance and utilization of
resistance sources are pending. Several pests also
cause serious damages on okra (Table 4), such as the
tomato fruit worm (TFW) (Helicoverpa armigera) the most
destructive pest of okra. The TFW may be controlled by
trap cropping using pigeon-pea borders (Youm et al.,
2005). Such an approach is being followed on okra in
Niger, where the small size of okra fields and the farmer
practice of planting borders of other crops (example,
sesame, roselle etc.) are assets for the adoption of such
a technique (Ratnadass et al., 2010).

3596 Afr. J. Agric. Res.
Table 4. Economically important pests of okra in WCA.
Name (causal agent) Symptom Remarks/control measures
Leaf curl disease
(Okra Leaf Curl Virus,
OLCV)
Green-yellow mottling of leave, turn curved and irregular,
plants stunted and bear yellow or wrinkled fruits with dark
spots.
Resistant/tolerant cultivars not available;
weed management and control of virus-
transmitting whiteflies (Bemisia tabaci) using
insecticides
Powdery mildew
(Erysiphe
cichoracearum)
Mainly older leaves, petioles and stems are affected. A
large part of the leaf surface is covered by the talc-like
powder composed of fungal spores. Spores are easily
blown by winds and helps disease to spread.
Selection of field far from source of inoculum;
weed management and application of
selected fungicides
Cercospora
(Cercospora
abelmoschi)
Brownish spots on lower leaves that contain fungal spores;
later leaves become yellow and drop
Weed management to reduce source of
inoculums
Shoot and fruit borer
(Earias spp.)
Larvae bore into the tender shoots, developing buds,
flowers, fruits and feed on inner tissues. The affected
shoots wither and growing points are killed, damaged buds
and flowers fall.
Use of ash on young larvae
Tomato fruit worm
(TFW; Helicoverpa
armigera)
Young larvae feed on tender foliage, advanced stage/s
attack the pods and one larva may destroy many pods.
External symptoms appear in the form of a bored hole.
Use of insecticides, neem extract, Bacillus
thuringiensis; weed management; rotations
with non-host crops; trap crops e.g. pigeon
pea
Cotton seed bug
(Oxycarenus
hyalinipennis)
Feeds on okra seeds. Results in considerable reduction in
germination rate Removal of weed and malvaceous hosts near
okra fields
Red spider mites
Colonies of mites can be found feeding on ventral surface
of leaves, resulting in yellow spots on dorsal surface. Use of crop resistance; application of specific
acaricides; weed management
Root knot nematodes
(Meloidogyne spp.)
Plants wilt and appearance of root galls/knots of different
sizes and infected roots also become enlarged and
distorted.
Weed management; crop rotation and
intercropping; mix cropping or cover cropping
with non host crops
Abiotic stresses
Unlike most of the popular vegetables, okra is
traditionally cultivated as a rain-fed crop in the region.
However, during the initial one month after sowing,
optimum soil moisture is required for good crop
establishment. Okra, being a tropical crop, is also
sensitive to the mild winters of the Sudano-Sahel.
Drought and salinity are major abiotic factors adversely
affecting okra production in the region.
CONCLUSION
Although the region of WCA has diverse genetic
resources of indigenous crop species, these have not
received sufficient effort for genetic improvement. It is
evident that adaptations to climate change by rural
communities over the past three decades have combined
institutional supports as well as technical fixes like faster-
maturing crop species and cultivars (Vermuelen et al.,
2008). The availability of improved planting materials and
technology pertaining selected crop species like okra
would further enhance livelihoods of the poor. Dietary
portfolio studies to maximize reduction of low-density
lipoprotein cholesterol have indicated that plant-based
diets (rich in viscous fibers) may be an effective strategy
for the prevention of hyperlipidemia. Fortunately, okra
along with eggplant is considered by medical experts as
the most important vegetable sources of viscous fiber
(Kendall and Jenkins, 2004). With expanding research
and developmental programs, AVRDC – The World
Vegetable Center and its partners are poised to under-
take long-term research to unlock recognized potential of

okra for food, nutrition and income security not only in
WCA but also in East and North Africa, and several
regions of Asia. Okra’s potential as an industrial crop also
has been tested in the developed world (Camciuc et al.,
1998). The development and use of resistant/tolerant
cultivars against major pests and their promotion is often
a more rewarding and appropriate option for the
sustainability of smallholder. This is especially relevant in
the developing and underdeveloped world, where farmers
often do not have the capability to diagnose pests and
have limited access to good-quality pesticides. In
addition, pesticide abuse leads to adverse impacts on
human and environmental health, and there are
increasing reports on the development of pesticide
resistance in pests. Nevertheless, we fully recognize that
resistance breeding and other management tactics based
on agro-ecological approaches are complementary, and
should not be viewed or considered in isolation. It is not
possible to extend the list of pests chosen to be tackled
through resistance breeding and/or genetic engineering,
nor are all biotic stresses amenable to effective control
via genetic pathways.
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