Rice In West Africa Research Articles

The search for new models for organizing regional agricultural research in the post-colonial era: Rice in West Africa

ABSTRACT The West African Rice Development Association (WARDA), created in 1971 as a regional network of rice research stations and governed by member countries, was unique within the system of international agricultural research centers that emerged in the post-colonial era. This paper reviews the actors, the actors, their motives, and the political and organizational debates involves in establishing WARDA. In particular, it traces the roles and interests of the former colonial powers, especially the French, the newly independent countries of the region, international organizations, and US foreign assistance and philanthropic agencies. Although all agreed that rice research was a priority for regional cooperation, the design of WARDA stimulated debates around centralization, governance, and funding of international research that continue until today.

Climate change-induced reduction in agricultural land suitability of West-Africa's inland valley landscapes

CONTEXTAlthough rice production has increased significantly in the last decade in West Africa, the region is far from being rice self-sufficient. Inland valleys (IVs) with their relatively higher water content and soil fertility compared to the surrounding uplands are the main rice-growing agroecosystem. They are being promoted by governments and development agencies as future food baskets of the region. However, West Africa's crop production is estimated to be negatively affected by climate change due to the strong dependence of its agriculture on rainfall. OBJECTIVEThe main objective of the study is to apply a set of machine learning models to quantify the extent of climate change impact on land suitability for rice using the presence of rice-only data in IVs along with bioclimatic indicators. METHODSWe used a spatially explicit modeling approach based on correlative Ecological Niche Modeling. We deployed 4 algorithms (Boosted Regression Trees, Generalized Linear Model, Maximum Entropy, and Random Forest) for 4-time periods (the 2030s, 2050s, 2070s, and 2080s) of the 4 Representative Concentration Pathways (RCP2.6, RCP4.5, RCP6.0, and RCP8) from an ensemble set of 32 spatially downscaled and bias-corrected Global Circulation Models climate data. RESULTS AND CONCLUSIONSThe overall trend showed a decrease in suitable areas compared to the baseline as a function of changes in temperature and precipitation by the order of 22–33% area loss under the lowest reduction scenarios and more than 50% in extreme cases. Isothermality or how large the day to night temperatures oscillate relative to the annual oscillations has a large impact on area losses while precipitation increase accounts for most of the areas with no change in suitability. Strong adaptation measures along with technological advancement and adoption will be needed to cope with the adverse effects of climate change on inland valley rice areas in the sub-region. SIGNIFICANCEThe demand for rice in West Africa is huge. For the rice self-sufficiency agenda of the region, “where” and “how much” land resources are available is key and requires long-term, informed planning. Farmers can only adapt when they switch to improved breeds, providing that they are suited for the new conditions. Our results stress the need for land use planning that considers potential climate change impacts to define the best areas and growing systems to produce rice under multiple future climate change uncertainties.

Changes in production, yields, and the cropped area of lowland rice over the last 20 years and factors affecting their variations in Côte d′Ivoire

To meet high demand for rice in West Africa, many governments and the regional and international donor community embarked on ambitious rice sector development. The questions are how much rice farmers have increased rice production in West Africa in the past two decades and what factors have contributed to the increase in rice production there. As a case study on lowland rice farming in central Côte d′Ivoire, we aim to describe changes in production, yields, the cropped area, and agronomic practices between 2000 and 2020, and to identify factors affecting rice yields and cropped area. Farm surveys were conducted in 2000 and 2020 around the city of Bouaké in Côte d′Ivoire to construct panel data, and descriptive and multiple regression analyses were performed. Rice production increased by an average of 89% over the 20 years, of which 26% and 63% increase in rice production were attributed to the increase in yields and the cropped area, respectively. Yield variation was 0.1–8.0 t/ha and 0.2–7.0 t/ha in 2000 and 2020, respectively, with medians of 1.6 and 2.4 t/ha. Farmers using low inputs relative to the land area tended to increase their cropped area. Changes in agronomic practices had limited impact on yield increase except for farmers’ adoption of a new variety and its impact on yields. These results indicate a need to understand the causes of poor adoption of agronomic practices such as fertilizer use and water management practices, and to identify the associations between yields and biophysical factors. These could help identify strategies for narrowing the yield gap through the diffusion of yield-enhancing agronomic practices. • Changes in rice production and agronomic practices were assessed over 20 years. • Production, yield, and cropped area increased by 150%, 30%, and 100%, respectively. • Yield and area contributed to increased production by 26% and 63%, respectively. • Farmers cultivating rice extensively tended to increase their cropped area. • Except for adopting new varieties, agronomic practices were not changed.

High-throughput phenotyping for drought tolerance in rice

Most lowland rice in West Africa depends mainly on rainfall for water supply. Drought is consequently one of the major constraints on rice production, drastically affecting both plant growth and development. The objective of this work was to study the impact of water deficit both on canopy temperature and on chlorophyll fluorescence level, used as indicators of transpiration and photosynthetic activity. Measurements using infrared thermography and fluorimetry were taken on both 17 lines resulting from the cross IR64 X B6144F-MR-6-0-0 and their two parents plus one tolerant (APO) controls. These 20 lines were phenotyped after applying a drought constraint in a controlled laboratory environment in Montpellier (France) in 2013 and - 2014 and in field in the lowlands of Banfora and Farako-ba (INERA Burkina Faso) in 2014. Results showed that the drought stress sustained by the plants increased canopy temperature in all lines, entailing differential disturbance of the photosynthetic process, markedly depressed in susceptible lines. A classification of the lines with respect to their sensitivity to stress could be established by using the Drought Factor Index (DFI), and Crop Water Stress Index (CWSI) as was established a correlation between the phenotyping methods by infrared thermography and fluorimetry. This article propose an efficient application of combined imaging as a rapid and accurate phenotyping tool for crop yield improvement, in particular by monitoring the efficiency of plant responses to the fluctuating of environmental conditions. This study proved the efficiency of the method combining IR thermographie and fluorimetry as a field phenotyping tools for drought resistance.

Evaluation and Breeding of Lowland Rice Varieties for their Yield and Tolerance to Biotic and Abiotic Stresses in Benin and Togo: Implication for Genetic Improvement of Rice in West Africa

Evaluation and Breeding of Lowland Rice Varieties for their Yield and Tolerance to Biotic and Abiotic Stresses in Benin and Togo: Implication for Genetic Improvement of Rice in West Africa

Pathogenic Variability of Bipolaris oryzae Causing Leaf Spot Disease of Rice in West Africa

An assessment of rice crop resistance to Bipolaris oryzae, a causal agent of rice brown leaf spot or helminthosporium disease was carried out. Ten (10) irrigated and upland rice varieties were used in this study. Seven (7) isolates of B. oryzae from Burkina Faso, seven (7) from Côte d’Ivoire and six (6) from Togo were used. The ten (10) varieties were inoculated with B. oryzae strains to assess their effect and determine the resistance level of these varieties to rice leaf spot (Helminthosporium). The varieties Bouaké- AM, FKR60N, NIL130, V10, FKR62N and CY2 showed a good level of resistance against all the isolates. The incidence of the disease on leaves reached 62.22% of severity index. Results revealed also that the strain effects are not linked to their country of origin. The investigation on the pathogenicity of Bipolaris oryzae isolates displayed the existence of a pathogenic variability among the fungus populations. These findings suggest that the tested varieties possess resistance genes that can be used in varietal selection.

Identification of novel major and minor QTLs associated with Xanthomonas oryzae pv. oryzae (African strains) resistance in rice (Oryza sativa L.).

BackgroundXanthomonas oryzae pv. oryzae (Xoo) is the causal agent of Bacterial Leaf Blight (BB), an emerging disease in rice in West-Africa which can induce up to 50 % of yield losses. So far, no specific resistance gene or QTL to African Xoo were mapped. The objectives of this study were to identify and map novels and specific resistance QTLs to African Xoo strains.ResultsThe reference recombinant inbred lines (RIL) mapping population derived from the cross between IR64 and Azucena was used to investigate Xoo resistance. Resistance to African and Philippine Xoo strains representing different races was assessed on the RIL population under greenhouse conditions. Five major quantitative trait loci (QTL) for resistance against African Xoo were located on different chromosomes. Loci on chromosomes 1, 7, 9, 10 and 11 explained as much as 13 %, 37 %, 13 %, 11 % and 15 % of resistance variation, respectively. A major novel QTL located on chromosome 7 explained 37 % of the phenotypic variance to the African Xoo corresponding to race A3 whereas that on chromosome 11 is effective to all African races tested. Together with genes and QTLs for resistance to bacterial blight previously described, the QTLs described here were mapped onto the reference O. sativa subs japonica (var. Nipponbare) physical map.ConclusionWe characterized new resistance QTLs. While some co-localize with known resistance genes/QTLs to Asian strains, others are specific to African strains. We result with new information on genes and QTLs for resistance to bacterial blight that will be useful for controlling the disease.

A panel cointegration analysis and dynamic causality test of agricultural supply response to prices: The case of rice in West Africa

The paper provides a regional estimate of rice yield and acreage supply response to prices in West Africa. Using balanced panel data of seven countries covering 1991–2006, the study employs panel cointegration estimators, namely FMOLS and DOLS to estimate the long-run rice yield supply function and using one-step Blundell-Bond system GMM to estimate the short-run acreage supply function in the region. While the empirical findings from both estimators provide similar results, the estimates show that price of maize is a key determinant of rice yield and acreage and there is rice-maize substitutability in both the long-run and short-run in the study. The short-run Granger causality runs only from maize price to rice acreage, while long run causality of joint effect of the prices on the acreage supply is also evident in the study. Our results also show that the rice yield and acreage supply functions are unresponsive to own price in the short -run and long -run, respectively.

Assessing the Effect of Consumer Purchasing Criteria for Types of Rice in Togo: A Choice Modeling Approach

ABSTRACTThis study analyses rice consumer preferences in Togo and estimates consumers' willingness to pay (WTP) for the quality attributes of locally produced rice. For that purpose, a random utility model is applied to elicit the WTP for the most important rice purchase criteria. The model is estimated using a survey of consumers from 15 prefectures in Togo. The results show that imported rice is largely preferred to local rice, especially in urban areas. Cleanness and whiteness appear to be the most preferred attributes, especially for imported rice. Togolese consumers are willing to pay a premium of up to 46% of the actual price for cleanness and 53% for whiteness in locally produced rice. Also, taste and swelling capacity play an important role in the preference for locally produced rice. The results might be useful for breeders and policy makers in the ongoing effort to improve the competitiveness of local rice in West Africa both from quality and price perspectives.

Processes Underpinning Development and Maintenance of Diversity in Rice in West Africa: Evidence from Combining Morphological and Molecular Markers

We assessed the interplay of artificial and natural selection in rice adaptation in low-input farming systems in West Africa. Using 20 morphological traits and 176 molecular markers, 182 farmer varieties of rice (Oryza spp.) from 6 West African countries were characterized. Principal component analysis showed that the four botanical groups (Oryza sativa ssp. indica, O. sativa ssp. japonica, O. glaberrima, and interspecific farmer hybrids) exhibited different patterns of morphological diversity. Regarding O. glaberrima, morphological and molecular data were in greater conformity than for the other botanical groups. A clear difference in morphological features was observed between O. glaberrima rices from the Togo hills and those from the Upper Guinea Coast, and among O. glaberrima rices from the Upper Guinea Coast. For the other three groups such clear patterns were not observed. We argue that this is because genetic diversity is shaped by different environmental and socio-cultural selection pressures. For O. glaberrima, recent socio-cultural selection pressures seemed to restrict genetic diversity while this was not observed for the other botanical groups. We also show that O. glaberrima still plays an important role in the selection practices of farmers and resulting variety development pathways. This is particularly apparent in the case of interspecific farmer hybrids where a relationship was found between pericarp colour, panicle attitude and genetic diversity. Farmer varieties are the product of long and complex trajectories of selection governed by local human agency. In effect, rice varieties have emerged that are adapted to West African farming conditions through genotype × environment × society interactions. The diversity farmers maintain in their rice varieties is understood to be part of a risk-spreading strategy that also facilitates successful and often serendipitous variety innovations. We advocate, therefore, that farmers and farmer varieties should be more effectively involved in crop development.

Rice in West Africa: Dynamics, policies and trends

Rice is a staple in the African diet. The commodity accounts for 25% of overall cereal consumption, second only to maize. Over the past 20 years, West Africa has specifically experienced a large surge in rice consumption. Although local production has progressed, through the expansion of planted areas and improvement in yields, Africa's rice production remains insufficient to cover the rising needs that are driven by demographic growth, the increase in per capita consumption and urbanization. The continent, that was 80 per cent self-sufficient for rice in the 1960s, now covers only 60 per cent of its needs. Import volumes have boomed over the past 20 years, especially in West Africa. Due to its dependence on external supply sources, West Africa is exposed to instability on the international market. The 2008 price crisis constituted a significant shock, especially for the most deprived strata of the population. The crisis, however, led to positive reactions by private and public actors, including the adoption of new policies to support and develop domestic rice production. More or less ambitious initiatives were launched, and met with some initial success. However, the trend is weakening as rice imports have been increasing anew since 2010. Today, West Africa remains the major rice importing region, accounting for 20% of global imports.

Rice and irrigation in West Africa: Achieving food security with agricultural water management strategies

West Africa's rice imports currently satisfy 70% of the soaring local demand, worsening the food vulnerability of an increasingly urbanized population. Despite considerable rice-growing potential, lack of water control systems, access to improved seeds, agrochemicals and appropriate mechanization have resulted in modest production growth rates, unable to alter the region's dependency on imported rice. Governments aim to boost production with import duties and input subsidies. However, questions remain as to whether these policies enable the rice sector to respond to changing consumers preferences for high grade rice and to contribute to national economic growth. We present the results from a Policy Analysis Matrix (PAM) on rice production in Ghana, Burkina Faso and Niger and under three water management systems: irrigation (public scheme), supplemented rain-fed (rainfall aided by autonomously-sourced water supplies) and purely rain-fed. Our results show that policy interventions in these West African countries (i.e., input subsidies and import taxes) did not significantly enhance the profitability of rice production to farmers due to the effect of market failures (limited capital access and non-competitive market for rice) and the low quality of local milled rice. The PAM results point strongly to the importance of improving rice quality and yields through more efficient water management and post-harvest handling/processing and targeted breeding to match consumers' preferences.

Incidence of rice stripe necrosis virus in upland rice in West Africa

Rice stripe necrosis (RSNV) is caused by a virus transmitted by the soil-borne fungus Polymyxa graminis. The disease is characterized by seedling death, leaf stripes and necrosis, and plant malformation. The disease was reported by Louvel and Bidaux in 1977 in Cote d’Ivoire, West Africa, and the virus was isolated by Fauquet and Thouvenel in 1983.

Deep roots: rice farmers in West Africa and the African diaspora

List of Tables Orthography Introduction 1. The Rio Nunez Region: A Small Corner of West Africa's Rice Coast Region 2. The First-Comers and the Roots of Coastal Rice-growing Technology 3. The Newcomers and the Seeds of Tidal Rice-Growing Technology 4. Coastal Collaboration and Specialization: Flowering of Tidal Rice-Growing Technologies 5. The Strangers and the Branches of Coastal Rice-growing Technology, c.1500 to 1800 6. Feeding the Slave Trade: The Trade in Rice and Captives from West Africa's Rice Coast Conclusion Appendix I.1 Fieldwork Interviews Appendix I.2 Rice Terminology in Atlantic Languages Spoken in the Coastal Rio Nunez Region Notes Bibliography Index

Response of lowland rice to agronomic management under different hydrological regimes in an inland valley of Ivory Coast

A large proportion of the rice in West Africa is produced in rainfed lowland ecosystems, mainly in inland valleys. The hydrological conditions (duration and intensity of flooding) vary with the toposequence position between the fringe and the centre of the valley. Production methods tend to evolve from the currently predominant unbunded plots without external input use, to input-intensive production in bunded plots. Agronomic management interventions co-evolve and may include varietal choice, herbicide use, and mineral N fertilizer application. The response of rice and the associated weeds to such interventions is likely to vary with the prevailing hydrological regime. A 2-year field experiment was conducted in northern Ivory Coast to determine the impact of water regime (plot position in the valley, presence of bunds) and input use (mineral N fertilizer and herbicide) on the productivity (yield and N use efficiency) of traditional and modern rainfed lowland rice cultivars and the biomass and composition of the associated weeds. Installing field bunds reduced seasonal variations in ponded water depth and resulted in a mean increase in rice grain yield of 30–40% ( p < 0.005). This increase was associated with a 25% lower cumulative weed biomass and a several-fold increase in the agronomic use efficiency of applied mineral N in bunded than unbunded plots. Under low input management, traditional varieties tended to out-yield modern varieties in unbunded plots. Improved crop management such as herbicide and fertilizer application, and the construction of field bunds was more effective to increase the yield and N use efficiency in the flooded valley centre than in the drought-prone valley fringes. There is a need for site-specific targeting of modern cultivars, land development and improved production methods in the inland valleys of the West African savanna zone.

Morphological and physiological responses of rice seedlings to complete submergence (flash flooding)

Reducing damage to rice seedlings caused by flash flooding will improve the productivity of rainfed lowland rice in West Africa. Accordingly, the morphological and physiological responses of different forms of rice to complete submergence were examined in field and pot experiments to identify primary causes of damage. To characterize the physiological responses, seedlings from a wide genetic base including Oryza sativa, O. glaberrima and interspecific hybrids were compared using principle component analysis. Important factors linked to flash-flood tolerance included minimal shoot elongation underwater, increase in dry matter weight during submergence and post-submergence resistance to lodging. In particular, fast shoot elongation during submergence negatively affected plant growth after de-submergence. Also shoot-elongating cultivars showed a strong negative correlation between dry matter weight of the leaves that developed before submergence and leaves developing during submergence. Enhancement of shoot elongation during submergence in water that is too deep to permit re-emergence by small seedlings represents a futile escape strategy that takes place at the expense of existing dry matter in circumstances where underwater photosynthetic carbon fixation is negligible. Consequently, it compromises survival or recovery growth once flood water levels recede and plants are re-exposed to the aerial environment. Tolerance is greater in cultivars where acceleration of elongation caused by submergence is minimal.

Spatial variability of indigenous supplies for N, P and K and its impact on fertilizer strategies for irrigated rice in West Africa

Present nutrient management recommendations for irrigated rice in West Africa are typically uniform for large regions. Even with optimal crop management, spatial variability of indigenous nutrient supplies may cause low fertilizer efficiency, low productivity of expensive inputs and high losses to the environment. Substantial efficiency increases were achieved with site- and season-specific nutrient management approaches, but the relative importance of different components (site or season) or of the precision level used (field, scheme, or region) remained unclear. We conducted a field trial in the Senegal River valley to investigate short-range variability of indigenous nutrient supplies of N (INS), P (IPS), and K (IKS) on a three hectare farm, and subsequently used the field data and simulation tools to study the agro-economic effects of fertilizer management options with different precision levels.

Nutrient Distribution in the Profile of Valley Bottom Soils Cultivated to Rice in Ghana

ABSTRACT The consumption of rice has increased in Ghana recently, but supply cannot meet demand; hence, there is a large annual importation to make up for the deficit. In Ghana, rice is cultivated under three main systems, namely rain-fed upland conditions, irrigated conditions, and rain-fed lowland conditions. Due to unpredictable rainfall, production under rain-fed conditions has been very unstable. Fortunately, inland valley systems (IVs), which have been cited by many authors as the environment best suited for efficient and sustainable rice production, abound in this country. This study was therefore undertaken to determine the soil nutrient status, and to document a plant species distribution that is useful for nutrient cycling in the IVs of the Ashanti region of Ghana. The goal is to develop a sustainable sawah-rice production system.** Valley bottom soil samples for laboratory analyses were collected from standard soil profiles in areas under use for rice cultivation or capable of supporting rice. Results showed these soils to be slightly acidic (topsoil mean pH = 5.7) with low exchangeable acidity [0.10 cmol(+)/kg]. Mean topsoil total carbon (C), nitrogen (N), and available phosphorus (P) (Bray 1) were 1.8%, 0.20%, and 4.4 mg/kg, respectively. Exchangeable cation [cmol (+)/kg] values of surface soils were 0.3 for potassium (K), 5.1 for calcium (Ca), 1.8 for magnesium (Mg), and 0.2 for sodium (Na), respectively. The concentrations of C, N, and most cations decreased down the profile. However, the overall fertility levels were well within the normal ranges for IVs of West Africa. The species dominating the valley bottoms were fairly similar in their carbon content. However, Manihot esculenta and Mallatus oppositifolium of the family Euphorbiaceae were higher than other species in N content. Species belonging to the family Euphorbiaceae were lower in P content (which ranged from 0.9 to 3.7 g/kg) while Physalis angulata and Manihot esculenta contained the highest (3.9 and 3.6 g/kg) P, respectively. The variable nutrient composition of these species has implications for nutrient cycling in the ecosystem. Knowledge of nutrient status of IVs will greatly assist in efforts at adopting the Asian type of sawah rice cultivation. If supported with appropriate farming practices that return crop residues to the soil and utilize inorganic fertilizer or organic manures, the inland valley ecology can contribute significantly to food security, especially of rice, and also conserve the environment. **The term sawah refers to bunded and leveled rice fields with both irrigation and drainage gates. It is of Malayo-Indonesia origin. The English term paddy originated from the Malayo-Indonesian word padi, meaning rice plant. It refers to unhusked rice in West Africa. Most of the paddy fields in the Asian countries fit the definition of sawah. However, the term paddy field refers only to a rice field, including upland rice fields in West Africa. To avoid any confusion between a rice plant paddy and the improved man made rice-growing environment, the authors use the term sawah.

Urban consumer preferences and sensory evaluation of locally produced and imported rice in West Africa

Parboiled rice produced in Ghana is of poor quality and is being overtaken by imported rice. This study sought to investigate consumer preference and relate sensory attributes with consumer acceptability of rice. The majority of consumers preferred imported raw and parboiled rice to that produced locally. Acceptability was influenced by location and gender. Individual preferences of consumers varied and four different segments of consumers with similar liking of the rice samples were identified. The largest three segments (86% of consumers) preferred the imported rice but differed in their preferences for the local rice. A niche segment (14%) mostly preferred traditional local rice. Regression models to predict consumer preference from the sensory panel scores were based on either brown colour of the cooked rice or unshelled paddy in the uncooked form. The models were suitable for three of the consumer segments representing 86% of the consumers. This suggests that while a sensory panel could be used to rapidly monitor consumer acceptability in product development, it was not valid for all consumers. The implications of these findings are discussed.

Field screening of diverse rice genotypes for weed competitiveness in irrigated lowland ecosystems

Weeds cause considerable yield losses in irrigated rice in West Africa, particularly where sub-optimal crop management or limited resources hamper production. Because of the recent focus of regional breeding programs in West Africa on a wide diversity of interspecific (O. sativa indica×O. glaberrima) and intraspecific (O. sativa×O. sativa) crosses for lowland systems, new genotypes with promising yield potential and putatively improved weed competitiveness are now available. Our study intended to establish a screening methodology for weed competitiveness in irrigated lowlands, to evaluate weed competitive abilities of diverse rice genotypes, and to relate several morphological plant characteristics with competitive abilities. A selection of 25 cultivars and advanced breeding lines was grown under irrigated conditions during the 2000 wet season (WS) and the 2001 dry season (DS) at Ndiaye (Senegal), and their reaction to four different competition levels was assessed. Competition was greatest where the test lines were grown with a mixture of an improved O. sativa indica cultivar and natural weed growth. Average yield losses across rice lines were 36% in the WS and 31% in the DS, but differences between lines were highly significant in both seasons and yield losses ranged from 0 to 84%. Competitive abilities were not related to yields without competition. In the DS, several of the new lines combined high yield with good competitiveness and outperformed the currently widely used check variety. Height, tiller density, specific leaf area (SLA), leaf area index (LAI), and growth duration were mostly negatively related to yield loss. Plant characteristics measured in monoculture had no explanatory value for the competitive ability of tested lines, indicating that screening under conditions of competition with weeds is preferable. Competitive abilities of several lines were stable across sites, years, and seasons; in others, they were strongly influenced by season. The simplified experimental layout can be used to screen advanced breeding lines or established cultivars with moderate resources (e.g., space, seed, labour). Including such a screening in the breeding process would enable more weed competitive cultivars to be identified and would be likely to contribute to increased resource-use efficiency, reduced yield losses, lower costs, and less reliance on herbicides in rice-based lowland systems.