Journal ofInternational Cooperation for
Agricultural Development

J Intl Cooper Agric Dev 2022; 20: 13–25

Study Text

Prospect of rice development in Africa
Jun-Ichi Sakagami
Faculty of Agriculture, Kagoshima University, Kagoshima 890-0065, Japan

Received: December 23, 2021
Abstract. Establishing sustainable food security in the midst of a natural environment that is changing on a global scale isone of the major challenges facing humanity. Particularly in tropical and subtropical regions, environmental problems such as
desertification, unstable crop production due to drought, and loss of forests, as well as social unrest due to rapid population
growth, are increasing. Many developing countries are located in these regions, and it is clear that urgent measures must
be taken to solve these problems. Among them, the sub-Saharan region of Africa tends to have stagnant economic growth
due to the economic burden of food imports to compensate for rapid population growth. We believe that we must do ourutmost to build a sustainable agricultural system that utilizes limited resources in order to contribute to the development ofagriculture in this harsh natural environment and economic crisis. The origin of rice cultivation in Africa dates back to 3500
years ago. Recently, the Africa Rice Center has developed interspecific hybrids, NERICAs, which are expected to contributeto food self-sufficiency in the region. The Japanese government and the Japan International Cooperation Agency have been
supporting and contributing to the development of rice production in Africa. The author has been conducting various research
projects on rice production with various international and domestic research institutes in the region for about 30 years. In
this chapter, the history of Japan’s technical cooperation for rice development in Africa and the characteristics of the rice
ecosystem will be explained. The functions and problems of interspecific hybrids, which have been developed recently andare being promoted throughout Africa, are also introduced. Furthermore, the characteristics and research results regarding
African rice, a genetic resource unique to Africa, will be described. Finally, the future direction of rice cultivation in Africa
is proposed by introducing examples of current efforts.
Key words: Africa rice, CARD, Farming system, NERICA, TICAD

Environment surrounding ricecultivation in Africa
It is important for the international community,
including Japan, to achieve sustainable economic growthand poverty reduction in Africa from a long-term perspective. It goes without saying that the development of agriculture is essential for economic development and poverty
reduction in African countries, where approximately 60 to
80% of the population is engaged in agriculture. However,agricultural development in Africa is hampered by various
problems such as the vulnerability of agricultural management due to poor environment and disasters, production
instability due to problematic soils and low fertility, andlow crop productivity due to underdeveloped cultivation technology (Fig. 1). Furthermore, as the population

Fig. 1. Small-scale paddy fields inflood-prone areas of Guinea

J Intl Cooper Agric Dev 2022 13

grows and the area of cultivable land per capita decreases,
reducing poverty requires increasing cropland productivity, introducing promising crop species and varieties, anddeveloping stable production technologies1).
In Africa, there has been high demand for rice inrecent years, and consumption has been increasing rapidly.
On the other hand, the increase in rice production has notbeen commensurate with the significant increase in riceconsumption; and imports from Asia, North America, andother regions have tended to expand year by year. The
demand for rice in Africa started to increase in the 1970’s;
at the same time, West African countries that had formed
rice-growing regions came together and established WARDA (West African Rice Development Association, now
the Africa Rice Center) with the support of the Food andAgriculture Organization (FAO) and other organizations.
Japan has been actively supporting WARDA’s researchand dissemination programs, including the improvementof rice varieties suitable for Africa, and in 2000, NERICA(New Rice for Africa) was developed for upland rice. On
the other hand, since farmers in Africa still lack experienceand knowledge of rice production, and the research andextension systems that support farming activities are notfully developed, the actual production of rice that meetsthe needs of farmers has not progressed significantly. We
are still waiting for the rice production in certain areas,
which is expanding slightly, to gradually spread to surrounding areas. Under these circumstances, at the fourthTokyo International Conference on African Development(TICAD IV) held in 2008, the Japan International Cooperation Agency (JICA) announced the establishment of the
Coalition for African Rice Development (CARD) as one of
the Japanese government’s agricultural sector partnerships
with Africa. This was the beginning of Japan’s full-scale
support for rice cultivation.

Japan’s support for rice cultivation in
AfricaAfrican countries achieved national independence
one after another around 1960. At that time, the focus ofagricultural research inherited from the colonial era was onlarge-scale farms. In the 1970s, Japan began full-scale cooperation for technology development and dissemination
for the agricultural sector, mainly through JICA, in model
areas in Africa where large-scale irrigated rice cultivation
was possible. Specifically, through grants and grants-inaid, JICA developed irrigated paddy fields, establishedtechnical training centers, and dispatched teams of experts
to support the transfer of technology. As a result of thetechnical cooperation, dramatic yield improvements havebeen achieved in model areas such as the Moshi Rural
14 J Intl Cooper Agric Dev 2021

District in Kilimanjaro in Tanzania and the Mwea Districtin Kenya. This rice cultivation technology introduced thetransplanting production system, one of the Asian-stylemethods of cultivation management, and established ahigh-input fertilizer system. In addition, the introductionof agricultural machinery to improve work efficiency was
also promoted. In the latter half of the 1980s, large-scale
irrigation facilities in many areas became obsolete, andthe number of government employees involved in facility
management was drastically reduced under the structuraladjustment policy. Subsequently, the focus of agriculturalresearch shifted to small- and medium-scale farms. As aresult, since the latter half of the 1990s, the trend of aid haschanged drastically to poverty reduction and food security;
thus, cooperation in small-scale irrigated rice cultivation
aimed at helping poor small-scale farmers plan, construct,and manage their own rice has become common. Since
2009, the National Crop Resources Research Institute in
Uganda, East Africa, has been conducting a project to promote rice cultivation and conducting training and researchin a wide range of fields with the aim of expanding riceproduction and transferring appropriate technology.

Establishment of CARD and Japan’s
efforts(1) Background of the establishment of CARD

Since the latter half of the 1990s, the consumptionof rice has increased rapidly in Africa, greatly exceeding
the production growth in the region, necessitating increasing imports; concurrently, consumption is predicted to
grow substantially in the future. Since rice is one of the
major crops consumed in Africa with high potential for
production expansion in various regions, focusing on riceand mobilizing international support will highly impact
development and contribute to the promotion of rural areas
and the reduction of poverty as well as mitigating foodproblems in the medium and long terms. In light of thissituation, JICA, in collaboration with the Alliance for a
Green Revolution in Africa (AGRA), announced the establishment of CARD to work with rice-producing countries
at TICAD IV, as mentioned above. The development goalof CARD was to double the region’s rice production from
14 million tons in 2007 to 28 million tons in 10 years by
2018.
(2) CARD’s approach by growing environment

At CARD, in phase 1, we tried to increase production
through three main approaches: the introduction of improved varieties, improvement of cultivation techniques,and development of infrastructure. In addition, it is said that
there are 20 million hectares of unused lowland wetlands

Evolution and cultivation of riceFig. 2. Maturity of NERICA3 in Cote d'Ivoire

suitable for rice paddies in the region; and by properly
developing these ecosystems, we can expect to increase
production in a sustainable manner. CARD selected appropriate varieties, improved cultivation techniques, andpromoted necessary inputs (facilities, fertilizers, etc.) for
each type of cultivation environment. For irrigated paddy
fields, the project focused on rehabilitating existing irrigation facilities and strengthening water user associations;for rainfed lowlands, the project focused on establishingand disseminating models of rice cultivation development;
and for rainfed fields, the project focused on disseminating
improved varieties such as NERICAs and developing lowcost cultivation methods (Fig. 2).
(3) Proposed post-CARD activity plan

At TICAD VII, held in Yokohama in 2019, a new
CARD phase 2 was launched with the goal of further doubling rice production (from 28 million tons to 56 million
tons) by 2030. This followed the successful completion of
CARD phase 1 in 2018, which reached its goal of doubling the rice production volume in each country. CARD
phase 2 has expanded the target countries from 23 to 32
and focuses on the path to doubling production throughthe RICE approach (Resilience, Industrialization, Competitiveness, and Empowerment) in order to enhance thecompetitiveness of domestic rice and to promote further
collaboration with the private sector. Specifically, the keys
are: improving rice quality by strengthening the value
chain, improving post-harvest processing technology, andpromoting the participation and utilization of the private
sector; developing and propagating the use of irrigationand introducing crop rotation such as alternating field
crops and horticultural crops to counter climate change;
and improving livelihoods by increasing yields, profits,
and nutrition. In addition, gender considerations, such as
reducing the workload of women, may also be important.

The species of rice cultivated are Oryza sativa L.
and O. glaberrima Steud. The former is called Asian ricebecause its cultivation originated in Asia, and the latteris similarly called African rice and is thought to have
evolved in different regions of Africa 2). Various theoriesof the origin of rice cultivation are related to the evolutionof wild rice to cultivated rice. It is also commonly said
that the wild types of cultivated species are genetically O.
rufipogon Griff. and O. barthii A. Chev. Sakagami et al.3)
defined the annual type as those that die within a year despite adequate growing conditions and the perennial typeas those that survive longer. O. sativa varies from annual
to perennial; the subspecies japonica has perennial characteristics, and indica was found to exhibit a wide range ofcharacteristics from annual to perennial types. On the other
hand, we conclude that O. glaberrima is a single-fruiting
annual with none of O. sativa’s major variations. There aremany theories as to how the species evolved during thisprocess of differentiation. For example, Vitte et al.4) compared the genomic behavior and sequence of transposons
and reported that japonica and indica may have diverged
about 200,000 years ago. There are various differences in
the growth of japonica and indica. As traits closely related
to cultivation, indica generally tends to shatter easily, andjaponica tends to shatter less easily; however, quantitative
trait locus (QTL) analysis using F2 of the japonica cultivar‘Nipponbare’ and the indica cultivar ‘Kasalath’ detected
shattering QTL on chromosomes 1, 2, 5, 11, and 12, and on
the long arm of chromosome 1. The QTL detected on thelong arm of chromosome 1 was reported to be the QTL withthe greatest power of action 5). In addition, archaeologicalanalysis related to the loss of degranulation in japonica
indicates that the cultivation of rice (paddy rice) occurredin the middle reaches of the Yangtze River in China about
7,000 to 10,000 years ago, and that rice (paddy rice) was
introduced to Japan about 3,000 years ago 6, 7). In general,
populations that retain genetic variation have high evolutionary potential, while homogeneous populations areprone to extinction when the environment changes and aresaid to be in an evolutionary cul-de-sac. In the case of wild
rice, the perennial type potentially contains a wide variety
of mutations and rarely reproduces by seed as long as the
habitat remains stable, so there is little opportunity for the
release of various mutant types 8). On the other hand, annuals are highly productive, but their genetic variation is so
low that they are unlikely to be able to generate cultivars
and differentiate further varieties. Therefore, it is possiblethat a primitive cultivar with considerable seed productivity and human-friendly characteristics will emerge from anintermediate population of both seed and vegetative propaJ Intl Cooper Agric Dev 2021 15

gation breeding. However, as compared to japonica, which
has low genetic diversity, indica has greater diversity, i.e.,
it is better adapted to a variety of environments 9). Basedon these facts, it is reasonable to assume that indica andjaponica have evolved in the context of different genetic
variations. From this point of view, it is highly likely thatindica evolved from an intermediate-type wild species ina population that varied from annual to perennial, whilejaponica evolved from a wild species with strong perennial
characteristics. We also strongly support the theory that O.
glaberrima, which lacks monogenetic variation, evolved
from an annual wild species.

Study of the origin of rice cultivation
The geographic variation of many cultivated plants
was studied, and the location with the highest diversity
was assumed to be the origin of the crop, which was rice
(O. sativa) in the southwestern Himalayas 10). Although
this theory greatly influenced subsequent researchers, it
is now recognized that various factors are involved in theaccumulation of variation in a particular location, and thatthe center of diversity is not necessarily the origin of thecrop. In addition, there have been various theories of theorigin of rice cultivation, from isozyme analysis of rice totheories on the origin from Assam and Yunnan 11), to thetheory that the center of variation in cultivated rice is in
the region including Myanmar and Laos 12). In any case,the original site of rice cultivation must have had wild
rice in the past, and the ecological and genetic conditions
necessary for the differentiation of primitive cultivation
types must have been present. In order to approach theorigin of crops that have evolved in close association withhumans, it is essential to study not only biology but also
various other fields and integrate them. In addition, thegrowth of rice is not only influenced by genes, but also by
the environment, the so-called gene–environment (GxE)interaction, which may affect the expansion of rice cultivation. In these areas, a large number of QTLs obtainedby interspecific hybridization and natural hybridization
between wild and cultivated species have been identified 13). This suggests that some aspects of rice evolution
may have undergone a complex process. In Asia, it wascommonly believed that rice (O. sativa) originated from
Assam in India and Yunnan in China11). The genomes of1083 cultivated rice cultivars of O. sativa and 446 wild
rice lines of O. rufipogon collected from various parts of
the world have been sequenced to create a comprehensive
genome variation map. In addition, indica evolved fromcrosses between japonica and wild rice lines in Southeast
Asia and South Asia 14). Huang’s study was an extremely
valuable achievement, demonstrating the theory that rice
16 J Intl Cooper Agric Dev 2021

cultivation originated in South or Southeast Asia 2) using
genome analysis, an advanced modern technology. On theother hand, O. glaberrima, which evolved in Africa, has
never been the subject of modern breeding, and in recent
years it has been replaced by common rice, O. sativa originating from Asia. Its cultivation area is decreasing 15), andits genetic diversity and geographical conditions suggestthat it originated in the Niger River inland delta region ofpresent-day Mali.
In summary, based on the physiological, morphological, and genetic background of the different rice species,
it seems that O. sativa evolved from the wild species
O. rufipogon with annual to perennial variation, and theprocess of evolution is similar to that described by Huang
et al.14), where the subspecies O. sativa evolved fromthe wild species O. rufipogon in the middle reaches of
the Pearl River in China. This was followed by crosses
between O. rufipogon and japonica in Southeast Asia
and South Asia, which resulted in the annual to perennial
variation in indica. This allows us to explain the differentiation of the subspecies using ecological characteristics.
On the other hand, the lack of subspecies differentiation in
the monocarpic annual O. glaberrima and the very small
genetic variation as compared to O. sativa suggest that it
evolved from the wild annual O. barthii found in Africa.
Since O. glaberrima exhibits high flooding resistance 15),
this strongly supports the theory that it originated in theinland delta of the Niger River, a flood-prone region.

The beginning of rice cultivation in
AfricaThe history of rice cultivation in Africa dates backapproximately 3,500 years. At that time, rice native toAfrica was cultivated (Fig. 3). It is thought that the beginning of its cultivation was in the wetlands of the upper
reaches of the Niger River 16). Even today, more than 130

Fig. 3. Harvest of African rice in an
inundation area of Mali

varieties of African rice are known to have been plantedin the widespread river delta region, which is a treasure
trove of genetic resources 17). About 500 years after its
cultivation in the Niger River Delta, rice cultivation
began in the western Gulf of Guinea region (present-day
Senegal, Gambia, Guinea-Bissau, Sierra Leone, Guinea,
and Cote d’Ivoire)18). It is unclear when rice cultivation
began in earnest in African countries, but it was probably
after 1500, when Asian rice was introduced to the African
continent. When rice was first cultivated in Africa, it was
mainly grown by direct seeding, but by the time Asian rice
was introduced, some areas had already established row
cropping and transplanting techniques 18). Today, althoughsome areas have been mechanized and modern materials
such as pesticides and fertilizers have been applied, most
farmers in Africa are still engaged in rough rice cultivation,and their cultivation techniques are extremely immaturecompared to those in Asia.

Characteristics of African rice(1) ‌Morphological, physiological, and ecologicalcharacteristics

African rice is one of the cultivated species of therice genus, as mentioned above, and is mainly cultivated inWest Africa. During 30 years of research on rice cultivationin Africa, the author has confirmed the cultivation of African rice in farmer’s fields in Niger, Mali, Guinea, Senegal,
Sierra Leone, Ghana, Burkina Faso, and Benin. African
rice is known to be tolerant of environmental stresses andis adapted to the unique natural environment of Africa.
In the past, African rice was divided into deep-water andupland rice types; but in recent years, it has become clearthat these traits show continuous variation and are notclearly dichotomized 19). However, it is clear that the morphological, ecological, and physiological characteristicsof African and Asian rice are markedly different whencompared. Morphologically, African rice generally has avariation in brown rice color from light to dark red, withfewer bristles on the surface of the paddy and more often
a well-developed glume. The surface of the leaf blade also
has few hairs, as the species name—glabrous—implies.
The leaf ligule of the Asian rice plant is sharp and pointed,
while that of its African counterpart is rounded and small,an indicator that distinguishes the two. Another characteristic of African rice is that there are fewer secondary rachison the panicle than on Asian rice (Fig. 4). On the other
hand, ecologically, African rice is a monocarpic annual;
this is ecologically different from Asian rice, which canvary from annual to perennial 3). It also has a relatively
low number of tillers, but it has vigorous initial growth.
African rice has an extremely high shattering habit, which

Fig. 4. Plant of African rice mixed withpaddy fields in Guinea

is one reason for its low yield. Physiologically, the rate ofcarbohydrate translocation to the panicle after heading rice
is higher in African than in Asian rice, resulting in a shorter
ripening period 20). This growth trait is unique to annual
rice and may be advantageous for drought avoidance inpoor environments in Africa. With regard to drought
resistance, there have been reports that African rice has ahigher capacity to recover after drought than Asian rice.
It is also characterized by extremely high internode andleaf elongation under flooded conditions and by its ability
to avoid high-temperatures damage to flowers during theday, such as by early morning flowering 21). Furthermore,
it is highly resistant to African gall midge and rice yellow
mottle virus (RYMV) 22). Although there have been few reports on the difference in yield between African and Asianrice using experimental methods, African rice is generally
considered to have low fertilizer responsiveness and low
yield. This is because of its high degranulation during theripening stage, which results in yield losses 23). African
rice is a cultivated rice, but it seems to show some wild
characteristics as well. This may be related to the fact that
African rice has been selected less frequently by humans
than Asian rice in the history of rice cultivation.
(2) Characteristics of grain quality

From a grain quality analysis of a total of 27 Africanand Asian rice varieties (8 Asian and 19 African) collectedin West Africa (Guinea, Mali, Niger, and Senegal), two
Mali varieties were found to have particularly high white
rice protein content in African rice 17). Both of these aregrown in the inland delta of the Niger River. On the other
hand, no significant differences in amylose content andamylopectin short-chain ratio, which are representativeof starch characteristics, were observed between African
J Intl Cooper Agric Dev 2021 17

and Asian rice varieties. The high amylose and a low amylopectin short-chain ratio (L-type) characteristics of theAfrican rice are often seen in indica varieties of Asian rice.
It is known that rice with these characteristics generally
has a hard texture and is not sticky, both in cooked andcold rice. Therefore, it was thought that the texture of hardrice based on a high amylose and a low amylopectin shortchain ratio would suit the tastes of consumers who prefer
African rice. In the future, it is important to refer to thepreferences of local consumers when improving African
rice for local use.

Rice-harvested area, yield, andproduction in Africa and Asia
Figure 5-1 shows the harvested area of rice in Africa
and Asia from 1961 to 2020. From 1961 to 2020, the harvested area in Africa increased by a factor of 6.2 and in
Asia by a factor of 1.3. Also, in 1961, the rice-harvested
area of Asia was 39 times that of Africa, but in 2020, therice-harvested area of Africa decreased by 8.2 times toAsia. During this period, Africa’s production increased byabout 1,400 hectares and Asia’s increased by about 3,300
hectares.
In 1961, rice yields were about 1.6 t/ha in Africa and1.9 t/ha in Asia, but in 2020, rice yields in Africa increased
1.4 times to 2.2 t/ha and in Asia increased 2.6 times to
4.8 t/ha (Fig. 5-2). Rice yields in Asia increased from 1.2
times those in Africa in 1961 to 2.2 times those in Africa
in 2020.
In 2020, Africa produced about 38 million tons ofrice, while Asia produced about 680 million tons (Fig.
5-3). This represents an 8.8-fold increase in Africa and a
3.4-fold increase in Asia from 1981 to 2020. Meanwhile,the difference in rice production between Africa and Asia
increased from 190 million tons in 1961 to 640 million
tons in 2020.
From the changes in each parameter, it can be inferred that rice production in Africa progressed, since therate of increase in rice production during this period was
3.4 times that of Asia, while it was 8.8 times that of Africa
Thus, although the rate of production growth is high in
Africa, its production is still very low compared to Asia
today. This is related to the expansion of cultivated areas.
On the other hand, the level of rice yield in Africa hasremained stagnant, and therefore, in order to improve riceproduction in the future, it will be necessary to increase
cultivation area and yield as well.

18 J Intl Cooper Agric Dev 2021

Fig. 5-1. Change in rice harvested area

Fig. 5-2. Change in rice yields

Fig. 5-3. Change in rice production (Data from FAO)

Classification of rice farming systems
and issues in Africa
The agricultural systems in Africa can be broadlyclassified into wetland-adapted agriculture and drylandadapted agriculture based on differences in the water
environment. The former type is found in the GuineaSudan savannah climatic zone where there is abundantannual rainfall or in rice paddies where sufficient moisture
is available for crop growth during the cropping season;
the latter type is found in irrigated land in the Sahel region
where rainfall is limited or in fields that depend solely on
rainwater and not on groundwater for moisture. Rice iscultivated in paddy fields that are blessed with relatively
good moisture conditions and is classified into two types:
irrigated rice using river water or reservoirs, and rainfed
rice. There are also deep-water rice and floating rice.
Land-based rice is generally grown on highlands andslopes and requires sufficient rainfall during the growing
period, which limits the growing area.
In West Africa, especially in the Sahel region,
agriculture is facing many difficulties due to the harshnatural environment and the economic crisis. In the future,
it will be particularly important to establish a low-input,
recycling-oriented agricultural system that utilizes limited
resources. The challenge of maintaining stable yields must
be addressed now.

Rainfed lowland rice cultivation
Rainfed lowland rice accounts for about 52% of
all rice cultivation in Africa (2011). Irrigated rice fields
account for 16%, and rainfed rice fields 36%. In Asia, irrigated rice fields account for 59% of the total area of ricecultivation, while in Africa, rainfed rice fields are the main
form of cultivation (Fig. 6). The average yield of rainfed

Fig. 6. Rice growth in rainfed paddy fields in Guinea

rice in West Africa is 1.4 t/ha (2011). Asian rice is grownin most of the rainfed paddy fields, but African rice may
be grown in some cases, depending on water conditions.
The paddy fields are small in size, with a simple ridge orno ridge between rice fields, depending on the topography.
The paddy fields in the inland lowlands are fed by runoff
from valleys, groundwater, and rainfall. In recent years,
an increasing number of regions have adopted Asian-styletransplanting cultivation techniques; however, in someregions, direct seeding cultivation is being reevaluatedfor cost reduction. In this form of cultivation, it is often
reported that rice plants suffer from drought damage due toa shortage of water during the late stage of growth. Therefore, in some areas, early maturing varieties with a shortgrowing season have been introduced, but these varieties
often have low yields due to insufficient vegetative growth.
In such areas, rice varieties with different growing periods
are grown in the same area to avoid risk as an insurancecrop.

Upland rice cultivation
Upland rice is rice cultivated on flat land or on arable land slopes that are generally not flooded throughout
the crop season but rely only on rainwater. It may also begrown on mountain slopes or around wet forests (slash andburn). In both cases, yields are low at 1 t/ha (Fig. 7). In
addition to the monoculture of upland rice, maize is intercropped in Guinea, Niger, and Nigeria. In recent years, theintroduction of early maturing NERICA rice varieties has
been promoted, but the loss of genetic resources such as
local indigenous varieties has become a problem. Becauseof the dependence of upland rice on rainfall, the areas suitable for cultivation are limited. However, unstable rainfall
patterns contribute to the problem of water shortage, andadequate measures against water shortage are necessary to

Fig. 7. Seedling emergence in upland in Cameroon
J Intl Cooper Agric Dev 2021 19

increase yields. In addition, weed control and maintenanceof soil fertility are the major production-limiting factors
in cultivation. On the other hand, upland rice areas havesome cultivation advantages, such as the availability ofsolar radiation and temperatures sufficient for healthy rice
growth. Cultivation is carried out by direct sowing. Thereis a method of spreading the seed after plowing with atractor and then harrowing with the tractor over it. This isintended to avoid bird and drought damage by mixing thesown seeds with the soil. However, in many cases, the soil
is not sufficiently leveled, and differences in germinationand emergence conditions occur in the field due to differences in soil moisture conditions. There is a wide variety
of upland rice varieties, but in general, their panicle weightand number of tillers are lower than those of lowland
rice. Drought is a general problem in Africa. Therefore,
varieties that are drought tolerant or avoidant are needed.
NERICA varieties of upland rice are characterized by arelatively early growth period of 90–110 days in general,of which NERICA4 is said to be drought tolerant. In termsof improving weed-competitive ability, some African rice
varieties have excellent foliar development in the earlystage of growth.

Irrigated lowland rice cultivation
Rice cultivation in irrigated paddy fields requires thatfields be divided into sections by ridges and that water
management can be carried out freely (Fig. 8). Largescale irrigated paddy fields in Africa do not differ greatly
from those in Japan, but in most areas, rice is grown bytransplanting by hand. When irrigation water is available
and the pumping of water from rivers is possible, there
are two cropping seasons—wet and dry. In the dry season,
atmospheric humidity decreases and water consumption
through evapotranspiration increases; therefore, yields are

Fig. 8. Rice growth in irrigated paddy field in Guinea
20 J Intl Cooper Agric Dev 2021

usually higher than in the wet season due to sufficient solar
radiation. For example, in the paddy fields of the Niger
River Basin, irrigated rice cultivation using large-pumpwater intake has been widely practiced since the 1960s, andirrigation canals (0.3 to 2 m wide) have been constructedin paddy fields of 0.25 ha per plot. The average yield isover 4 t/ha. In particular, irrigated lowland rice areas are
spreading along rivers in Mali, Niger, and Nigeria, andthese areas have organized water user associations to contribute to large-scale rice cultivation. The varieties plantedin the irrigated paddy fields are diverse, but in general,they are modern varieties of semi-dwarf Asian rice. They
are often introduced mainly by the IRRI (International
Rice Research Institute), IITA (International Institute ofTropical Agriculture), and Africa Rice Center. In somecases, such as in Guinea, the National Research Institutes
have developed varieties through their own breeding programs. Irrigated rice fields in West Africa are often foundin rivers and coastal terrain in the Sahel region, making
them susceptible to salt damage and iron toxicity. For thisreason, salt-tolerant varieties are being introduced. In the
coastal mangrove areas of Guinea, seawater is pumped inand out of the paddy fields during the dry season by opening and closing the gates of the flume to reduce the salinityof the paddy soil, thereby making rice cultivation possible.
Among the irrigated rice NERICAs, some high-yielding
and flood-tolerant lines have been identified in the WAS(West Africa St-Louis) series grown at the Sahel branch of
the Africa Rice Center in Saint-Louis, Senegal24).

Deep-water rice cultivation
Deep-water rice cultivation is practiced in paddy
fields where the water table remains at 0.5 to 1 meter for
most of the growing period (Fig. 9). The morphologicaland physiological differences between floating rice andFig. 9. Rice growth in a deep-water field in Niger

deep-water rice are ambiguous, because floating rice isalso adapted to deep-water areas and is often treated as
deep-water rice. In addition, short-stemmed, high-yielding
varieties with the added elongation ability of floating rice,which can elongate internodes like floating rice when therice is flooded, are sometimes referred to as deep-water
rice. In Africa, the deep-water rice crop, like the floating
rice crop, is a mixture of African and Asian rice. The area
under deep-water rice cultivation in Africa is thought tobe about 10% of the total area of rice cultivation in Africa.
Deep-water rice is generally vigorous in its early stages,
and even when the water table is not rising due to flooding,the plants can grow to nearly 2 m in height25) In Guinea,
deep-water cultivation is relatively popular, with water
depths rising by up to 1 m, and some rice plants growing
more than 2 m in response. Deep-water rice has a relatively
long leaf blade, which allows it to avoid flooding andmaintain an aerobic metabolism by expanding its leaves
above the water surface. Deep-water-tolerant varieties
in Africa have been shown to have higher above-groundelongation during flooding and higher net assimilation
rates in leaf blades above the water surface17). Such aboveground-elongating varieties may be prone to collapse after
water withdrawal, so resistance to collapse is important26).
In deep-water areas of Africa, large seedlings with longgrasses are often transplanted to avoid the risk of flooding
during early growth. However, in this case, late transplanting often suppresses the increase in the number of shoots.
In the deep-water areas of the coastal regions of Guinea,
thick-stemmed indigenous rice varieties are often grown,
and modern improved semi-dwarf rice varieties are rarely
planted.

The challenge of selecting NERICA
rice(1) Upland NERICA

In 1992, 1130 lines of African rice were evaluatedfor characteristics related to short growing season, goodearly growth, and vigorous cropping; 8 lines were selected
for crossbreeding at the African Rice Center 27). Among
the resistance traits, they focused on weed competition,
trying to produce a rice plant with both the morphology ofAfrican rice with horizontally expanding leaves for earlyvegetative growth and the morphology of Asian rice withhigh-yielding plants with an excellent light-receiving system in the canopy for reproductive growth. Furthermore,
the breeding objective was to shorten the growing season
for drought avoidance as well. Interspecific hybridization
was started in 1992. As a result, promising lines were obtained from the WAB450 population that showed seed fertility in later generations. The parent variety WAB56-104

Fig. 10. Interspecific‌progeny cross between
O. sativa and O. glaberrima in Senegal

is a japonica of Asian rice, and CG 14 is an African ricecollected in the Casamance region of Senegal28). Several
hybrid lines were backcrossed, and promising populations
were selected from them (Fig. 10). In the first year, eachfarmer participated in evaluating the lines. Farmers visitedthe demonstration plots three different times during thegrowing season at the active tillering, heading, and harvesting stages and evaluated the lines regarding each of
the survey items. In the second and third years, farmers
took several lines of their choice to their own farms, cultivated them, and evaluated them. Seven varieties of upland
rice (NERICAs 1–7) were disseminated in 2000 and 11
varieties (NERICAs 8–18) in 2005. To date, the resultsof the pilot studies have revealed several characteristics
of NERICA varieties that are so-called high-yielding rice
varieties with good fertilizer tolerance and high inputs
that translate into higher yields. In addition, as mentioned
earlier, these varieties are characterized as early maturing
varieties with a growing period of about 90–110 days. On
the other hand, the weed-reduction effect is smaller thanthat of the African rice parent, and, in terms of drought
resistance, avoidance due to deep rooting differs among
varieties and is not sufficient. At the Africa Rice Center,
the number of rice grains per panicle was estimated to be
300–400, but it is unlikely that the number of rice grainsobtained can be replicated in the fields of actual farmers.
Since it is extremely difficult for African farmers, who
generally use low inputs, to obtain sufficient fertilizer forhigh yields, it is not easy to utilize the growth characteristics of NERICA varieties to achieve high yields for current
farmers, except those with fertile soil or who continuously
apply a certain amount of chemical fertilizer.
(2) Lowland NERICA

Since 2000, when NERICAs became incentive
J Intl Cooper Agric Dev 2021 21

Fig. 11. Growth‌of lowland type NERICA in Senegal

varieties, attention has been focused on the developmentof rainfed paddy fields in lowland areas with high yieldpotential in order to further increase yields. Since there arefew promising varieties in rainfed lowland fields in Africa
in general, the breeding of new varieties was expected. The
first objective of breeding rice NERICAs for lowlands was
to develop resistance to RYMV, a disease that is unique topaddy fields and for which there were no effective mitigation measures. Crosses were carried out at the Africa Rice
Center, mainly at the Sahel Branch (Fig. 11). Asian rice
indica type IR64 and African rice TOG5681 were usedas crosses. TOG5681 was selected as the parental line
for this cross because of its resistance to iron toxicity 29)
and RYMV. After two to four backcrosses with the Asianrice parent, selection continued in Burkina Faso, Mali,
and Togo, in addition to Saint-Louis, for genetic fixationof the lines. In the selection of lowland rice NERICAs,
farmer-participatory methods were used in the same way
as for upland rice: 60 varieties were produced in 2005,
and their yield potential of 6–7 t/ha effectively reduces
major environmental stresses in paddy fields 27). In 2006,
NERICA-L19 was registered in Cameroon; NERICA-L39
and 49 in Niger; NERICA-L19 and 20 in Sierra Leone;
NERICA-L19, 34, and 42 in Togo; and NERICA-L19, 41,
and 60 in Burkina Faso. In 2006, NERICA-L39 and 49
were registered in Niger, and NERICA-L19 and 20 wereregistered in Sierra Leone. In Gambia, WAS161-B-9-2,
WAS122-IDSA-15-WAS-6-1, and WAS127-B-5-2 wereregistered as varieties. Later, the variety was further promoted in East African countries.

Future prospects
We are already aware of the impact of climatechange on food production. The Sixth Report of the Intergovernmental Panel on Climate Change (2021) warned
that global warming will proceed faster than previously
22 J Intl Cooper Agric Dev 2021

assumed and that all regions will face increasing changes.
It proposed that “climate-resilient development” is a key
phrase in combating global warming, and it predicted thatclimate change will severely and negatively affect rainfed
agriculture in Africa. In rainfed agriculture, farmers haveto cope with year-to-year changes in weather even under
the current weather conditions; however, climate change
in Africa as part of global environmental change will makeit even more difficult for farmers to cope.
Rice cultivation is an agricultural practice that developed in Asia and has been established in regions that takeadvantage of abundant precipitation. In Africa, rice cultivation is vulnerable to climate change, and more-detailed
measures are needed. In this respect, the promotion ofrice cultivation in Africa needs to be considered differently from that in Asia. It is an important challenge for theinternational community to achieve sustainable economic
growth and poverty reduction in Africa from a long-term
perspective. It goes without saying that the developmentof agriculture is essential for economic development andpoverty reduction in Africa, where about 60 to 80% of the
population is engaged in agriculture. However, African
agriculture is hampered by various problems, such as thevulnerability of agricultural management due to disasters
and other unfavorable environments, production instability due to problematic soils and low fertility, and coarse
productivity due to underdeveloped cultivation techniques.
Furthermore, as the population increases and the area ofcultivable land per capita decreases, it is necessary to increase the land productivity of crops, introduce promisingcrop species and varieties, and develop stable production
technologies in order to reduce poverty; however, it is difficult to say that these goals are being achieved presently. On
the other hand, tropical Asian countries overcame a rapid
increase in population and decrease in cultivable land per
capita in the 1960s and increased food production throughthe “Green Revolution.” During Asia’s Green Revolution,
the productivity of rice increased dramatically due to the
spread of high-yielding varieties, the use of chemicalfertilizers, the installation of irrigation facilities, and thepromotion of mechanization. As a result, urbanites andchemical companies were enriched, but small-scale farmers did not benefit sufficiently, according to some reports;
however, there is no doubt that technological innovations
dramatically increased yields. In Africa, the Africa Rice
Center and the International Agricultural Research Organization have developed a high-yielding interspecific hybrid
variety of NERICA, which has been called a miracle rice.
This has contributed greatly to the increased rice production in Africa. However, rice production in the region has
not been able to keep up with the increase in consumption;
as a result, imports from other regions have increased tomeet consumption, worsening the region’s economy. Thissection explores reasons the Green Revolution of tropical
Asia has not been successful in Africa.
It is important to recognize that Africa is a different continent from Asia. The main differences between
Asia and Africa are the natural environment, population
density, educational level, religion, acceptance of foreigncultures, and infrastructure. In the agricultural sector, soil
fertility is generally lower in Africa than in Asia, which
is a major hindrance to improving crop productivity. In
Africa, rice cultivation is more susceptible to droughts
and other adverse environmental conditions. For example,
Africa has a higher percentage of upland rice cultivation
than Asia. This is due to the fact that African agriculture
has been influenced by European agriculture, which hasdeveloped mainly through fields or upland crops in thepast. In addition, Asian agriculture is relatively precise,
while African agriculture is characterized by coarsenessand generally low yields. The stagnation of African agriculture compared to that of Asia is due to a variety offactors, including the natural environment as well as thesocial and political background. On the other hand, there
are various agricultural technologies and traditional methods in Africa that are not seen in Asia, and since crops arecultivated according to the local conditions, it is possible
to make the best use of the agricultural environment andgenetic resources of each region. Therefore, it is desirable
to develop rural areas and agriculture that are suitable forthe agricultural environment of each region.
As mentioned above, the majority of people in Africa
are engaged in agriculture, and agriculture accounts for alarge proportion of income and GDP of the country. This is
why it is necessary to focus on poverty reduction in rural
areas in order to achieve economic development. Thisrequires support for agricultural and rural development
to improve agricultural productivity, increase agricultural
income, and improve living conditions. The African region contains about 25% of the world’s arable land but
produces only about 10% of the world’s food. In addition,it has about 60% of the world’s uncultivated arable land.
From this point of view, Africa’s agricultural development
potential is high. In West Africa, about 20 million hectaresof unused lowland wetlands have potential for rice cultivation30). In particular, in the delta region of the Niger River,
African rice, which is endemic to Africa, is grown, andtraditional farming methods are practiced. These methods
are characterized by the use of chemical-free fertilizers andpesticide-free cultivation management; since rice plants
exhibit floating rice characteristics that allow them to growin response to changes in the water table, we can conclude
that they are a cyclical agriculture crop suitable for poor
environments with extremely high flood avoidance17).

In the 1960s, African countries achieved national
independence one after another, and at that time, agricultural research inherited from the colonial era focused onlarge-scale farms. However, with the subsequent deterioration of the domestic economy and structural adjustments,
the budget for agricultural research and development
was drastically reduced, and the previous momentumof research and development was lost. For example, in
Kenya, the leader of East African countries, 12% of thegovernment budget was used for agricultural researchand development in 1965, but since 1990, only 3% of
the budget has been used for this purpose. In addition,
research and extension organizations now face a serious
shortage of human resources and equipment. On theother hand, the numbers of agricultural research institutes
and their researchers in African countries are relatively
high. This is due to the fact that each country or region
has its own agricultural research institute. It is not an
exaggeration to say that African agricultural production
today is mostly by small-scale farms, although there aredifferences among regions. From this point of view, it isnecessary to promote research and development according
to the type of management. In the future, it is necessary
to improve the quality of research in Africa’s agriculturalresearch institutes by promoting human resource development and to achieve synergy of research results by sharing
research among related institutes in neighboring countries.
On the other hand, it is extremely important to establish adissemination system that enables sufficient technologicaltransfer of research results with close cooperation between
the research and extension departments.
In order to realize an African version of the Green
Revolution, it is important to establish a sustainable andstable technological system, not only from the agronomic
perspective of improving yields. Therefore, it is necessary
to identify suitable crop species and varieties as well as
production technologies that can stably improve yields
under various unfavorable environmental conditions in the
African region. In addition, it is important to expand thearea available for cultivation. On the other hand, in the
African version of the Green Revolution, it is important todevelop and introduce high-value-added crops with highprotein and minerals to supply the nutrients necessary forhuman life, rather than just increase production throughconventional yield and area expansion. This new idea willcontribute to the development of high-value-added farming methods that make effective use of limited arable land.
In addition, we must (1) establish a production technology
system that is resistant to unfavorable environments, (2)develop generally adaptable crops and varieties that canmaintain stable yields, (3) develop and introduce highvalue-added crops, (4) develop human resources who can
J Intl Cooper Agric Dev 2021 23

lead research, and (5) build a feedback system for research
results.

SummaryWill Africa follow Asia in a Green Revolution inrice production? To develop African agriculture and rural
areas, which are still vulnerable despite medium- andlong-term technical cooperation and economic support
from international partners including Japan, it will benecessary to enhance the suitability of progressive agricultural technologies developed in Asia for Africa. However,the current hurdles are high, and it is not easy for African
agriculture, which is based on conditions different fromthose in Asia, to develop dramatically in a short period oftime. On the other hand, Africa has valuable plant genetic
resources and agricultural inputs that are not available inAsia, so it may be possible to develop them independently.
At the TICAD VI held in Kenya on August 27–28, 2016,
the Nairobi Implementation Plan was formulated. The planemphasizes the development of agricultural researchersand capacity building for women and youth. In order topromote Africa’s version of the Green Revolution, it is firstnecessary to develop excellent human resources. This isbecause the future and direction of Africa are largely in thehands of the African people themselves.
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