AfricaRice books and book chapters
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Item Application of Genomics in Supporting Efficient Conservation and Utilization of Plant Genetic Resources(Book Chapter, 2024-05-29) Wambugu, P.W.; Ndjiondjop, M.N.; Rangan, P.; Henry, R. J.Many gene banks have adopted various genomic tools and have integrated them into their routine genebank operations. In this chapter, we review the actual and potential applications of genomics in advancing seed bank-based ex situ conservation and utilization of plant genetic resources. Genomic tools are supporting germplasm acquisition efforts through conservation gap analysis and enabling the identification of rare, threatened, and novel genetic resources that need to be prioritized for conservation. Analysis of germplasm from different environments using transcriptomic approaches assists in identifying the candidate genes associated with desirable traits and biologically important pathways. Identification of genetic redundancy is enabling collection rationalization thus enhancing cost efficiency in plant genetic resources conservation. Genomics is providing greater capacity on developing core collections and trait-specific subsets thus promoting utilization of plant genetic resource collections. Emerging genomic technologies are providing capacity to support in situ conservation and biodiversity restoration using ex situ conserved diversity. Analysis of genome environment associations is enabling the identification of germplasm that potentially possesses the necessary adaptive capacity and desired traits. The lack of a standardized approach on documenting and sharing big genomic data being generated from ex situ collections however remains a major challenge in enhancing genomics-assisted conservation.Item Farmer Risk Preferences and Willingness to Pay for African Rice Landrace Seed: An Experimental Choice Analysis(Book Chapter, 2023-10-02) Arouna, A.; Tyack, N.; Aboudou, R.Most literature that investigates the impact of farmer risk preferences on agricultural technology adoption has focused on how risk preferences impact the adoption of technologies that enhance productivity but that may be riskier than local technologies. In this work, we elicit the risk preferences of smallholder rice farmers and investigate how these preferences impact how they value having access to seed of farmers’ varieties of African rice (Oryza glaberrima) maintained in the gene bank of the Rice Biodiversity Center for Africa. These varieties may have lower yields, but they may be more consistent and less risky given their adaptation to the local climatic conditions. We use a Becker–DeGroot–Marschak (BDM) mechanism to elicit farmers’ willingness to pay for small amounts of landrace seed (35 g) in Côte d’Ivoire. We find that farmers generally value having access to African rice landraces (with a mean willingness to pay of ~US$0.50), and that this willingness to pay is influenced positively by loss-aversion preferences (but not risk aversion), along with several other factors. This finding is in contrast with past evidence suggesting that loss aversion is connected to slower adoption of novel technologies, and suggests that the impact of risk preferences on technology adoption may depend on the potential ability of technologies to guard against economic losses.Item Rice research in the development of livelihoods and sustainable food value chains in Africa(Book Chapter, 2023) Manneh, B.; Jalloh, A.; Arouna, A.Item Supporting Prosperity through Better Mobility and Rural Reinvigoration(Book Chapter, 2023-01-31) Zougmoré, Robert B.; Castellanos, Andrea; Dossou-Yovo, Elliott Ronald; Gonsalves, Julian Francis; Lamien, Niéyidouba; Segnon, Alcade C.Item Iron toxicity tolerance in rice: Roles of Auxins and Gibberellins(Book Chapter, 2022) Daramola, O.S.; Shaibu, A.A.; Semwal, V.K.Rice is subjected to high iron (Fe) levels in acidic lowland soils which results in disturbance of basic metabolism, several changes in physiological processes and as a consequence reduction in productivity. In response to Fe toxicity in soils, rice like other plants produce a number of hormones (also known as phytohormones), including auxins, gibberellic acids and cytokinins. These hormones are organic substances that regulates plant growth and development, and play important role in rice defence against Fe toxicity. These hormones are part of signal-transduction pathway that stimulates reactions for Fe toxicity responses. The biosynthesis, transport, redistribution and conjugation of these plant hormones in rice has been shown not only to reduce high Fe inside rice plant tissue, but also to alleviate the adverse effect of Fe toxicity. In the present review, we discuss the conditions that enhances Fe toxicity in rice, effects of Fe toxicity in rice and tolerance strategies to Fe toxicity in rice. A special attention has been paid on the role and mechanism of phytohormones in enhancing tolerance and overcoming Fe toxicity-induced adverse effectsItem Overview of Long Term Experiments in Africa(Book Chapter, 2012) Bationo, A.; Waswa, Boaz Shaban; Abdou, A.; Bado, B.V.; Bonzi, M.; Iwuafor, E.; Kibunja, C.; Kihara, Job Maguta; Mucheru, M.; Mugendi, D.; Mugwe, J.; Mwale, C.; Okeyo, J.; Olle, A.; Roing, K.; Sedogo, M.The prevailing low food production in sub-Saharan Africa is an issue of great concern especially since Africa south of the Sahara is the only remaining region of the world where per capita food production has remained stagnant. This chapter reviews long-term experiments in Africa in the context of shifting paradigms related to tropical soil fertility management from first external input paradigm right through to the current Integrated Soil Fertility Management (ISFM) approach, which is a culmination of the participatory methods developed along the paradigm shift. Long term experiments (LTE) are an important source of evidence for soil fertility decline and provide crucial datasets for the development of sustainable management practices for tropical land-use systems and the amelioration of global climatic and environmental change impacts. A survey was undertaken to identify some ongoing long-term trials distributed across east, south and western Africa and in different agro-ecological zones. A long-term Experiment was defined as that extending over a period of over 5 years and more. Results from these trials are discussed in detail. Inference has been drawn from these findings and includes the following key findings: a) All long term trials showed yield decline, often with a relatively rapid fall to a low level equilibrium; b) At all sites, there were positive yield responses to one or more nutrients added as mineral fertilizers, which were consistent for the duration of the experiments highlighting the effectiveness of mine-ral fertilizers in increasing yield in arable farming systems in Africa; c) Soil organic matter (SOM) also declines significantly when land is cultivated; d) Prolonged treatments using only inputs of organic matter also showed yield declines, although the positive impact were sustained longer than for inorganic fertilizers alone in most cases; e) Rotational treatments, including sequences with legume crops and fallow periods had lower yield declines than monocultures; f) The best results invariably were those treatments that combined inorganic and organic inputs.Item Smallholder participation in value chains: The case of domestic rice in Senegal(Book Chapter, 2013-11) Colen, L.; Demont, M.; Swinnen, JohanItem Participation des petits exploitants aux chaînes de valeur agricoles: Le cas de la production locale de riz au Sénégal(Book Chapter, 2013-11) Colen, L.; Demont, M.; Swinnen, JohanItem Promise and contradiction: Value chain participation and women's empowerment(Book Chapter, 2021-11) Ihalaine, Markus; Shaikh, Sumer; Mujawamariya, Gaudiose; Mayanja, Sarah; Adetonah, Sounkoura; Tavenner, Katie; Elias, MarlèneWith the expansion of agricultural production for the global market, interest among research and development actors in developing more “inclusive” value chains has grown (Stoian et al. 2018a). While mainstream value chain development (VCD) has focused on enhancing the efficiency of processes along the chain, policies increasingly endeavor to address poverty, emphasizing the inclusion of poor and marginalized people in global markets (Bolwig et al. 2010). In recent decades, scholars and development agencies have directed attention toward the “gender gap in agriculture” (Huyer 2016), encompassing, among other things, women’s lesser access to market opportunities and to the benefits from cash crops (Pyburn et al. 2015). As a consequence, agricultural development initiatives increasingly aim to support the engagement of women in agricultural value chains (Sachs 2019). However, while promoting the engagement of women in markets and value chains is becoming entrenched in the global agenda for gender equality (Stoian et al. 2018a), systematic evidence demonstrating causal linkages or laying out a clear theory of change between participation and empowerment remains limited (Said-Allsopp and Tallontire 2014, Johnson et al. 2018).Item New breeding directions at AfricaRice: Beyond NERICA(Book, 2010) Africa Rice CenterItem Rice interspecific hybridization project: Research highlight 1999(Book, 1999) Africa Rice CenterItem Lessons from the rice crisis: Policies for food security in Africa(Book, 2011) Africa Rice CenterItem Rice research for development in Africa: Experience from AfricaRice(Book Chapter, 2019) Roy-Macauley, HaroldItem Molecular breeding and biotechnology for rice improvement in the developing world(Book Chapter, 2019) Zenna, N.; Manneh, B.; Atnaf, M.; Worede, F.Item Managing Fertilizer Recommendations in Rice-Based Cropping Systems Challenges and Strategic Approaches(Book Chapter, 2018) Bado, V.B.; Djaman, K.; Valère, M.C.Improving agricultural productivity to facing the fast growing food demands is the huge challenge of Sub-Saharan Africa (SSA). Fertilizer is a powerful productivity-enhancing input, but farmers of SSA use only 5 to 9 kg ha−1 of fertilizer, ten time less than Latin America and Asia (50 and 80 kg ha−1, respectively). Rice (Oryza sativa) is one of the most important food crops of SSA and rice consumption is growing faster than the consumption of any other commodity in Africa. Rice-based systems have high potential for improving food production through an efficient management of fertilizers. The biophysical environment, cropping systems and, socio-economic environment of farmers including market opportunities are the main factors for development of appropriate fertilizer recommendations. This paper makes a critical review of rice-based systems in Africa and the main achievements on fertilizer recommendation, and further identifies the main challenges and opportunities to improve fertilizer use efficiency in rice-based systems. The opportunities offered by the new concepts, modeling and decision support tools that have been recently developed for better management of fertilizers in rice systems have been discussed. Beyond the traditional techniques of blanket fertilizer recommendations by country, some suggestions are proposed to improve the utilization of the new concepts and decisions support tools for better management of fertilizer in the rice-based systems.Item Assessing the Impact of Collective Marketing of Paddy Rice in Innovation Platforms by Smallholder Producers in Benin(Book Chapter, 2018-01-01) Arouna, A.Market access is a major constraint of smallholder rice producers in sub-Saharan Africa (SSA). There is increasing evidence that acting collectively offers one way for smallholders to participate more efficiently in the market. This chapter aimed to identify the determinants of participation in collective marketing of rice in innovation platforms in Benin and quantify its impact on household income and food security. Unlike previous studies, we used the local average treatment effect parameter to assess the impact of collective marketing of rice. Data were collected from a random sample of 257 smallholder rice producers. Results showed that participation in collective marketing increased the income of rice farmers on average by USD 148/ha. Main determinants of participation in collective marketing of rice were membership in a farmer group, training, and agreement on price. This chapter concludes that better training and well-functioning farmer groups sustain the impact of collective marketing of rice on food security.Item Oryza longistaminata A. Chev. and Röhr(Book Chapter, 2018) Ndjiondjop M.N.; Wambugu P.; Dro T.; Mufumbo R.; Sangare J.; Gnikoua K.Oryza longistaminata is a distantly related wild rice relative found only in Africa. It is agronomically inferior to cultivated rice but possesses several latent useful traits that can be used to improve agronomically important traits in cultivated rice. These useful traits include strong rhizomes, a vigorous biomass, drought avoidance mechanisms, good weed suppression ability via allelopathy, and high nitrogen-use efficiency. It also possesses resistance to several biotic stresses such as brown plant hopper, nematodes, yellow stem borer, rice tungro bacilliform virus, blast, and bacterial blight. Recent studies have revealed that it is a good source of new alleles that can be used to improve yield-related traits in cultivated rice varieties. However, this potential is not well studied and is therefore not optimally exploited. Advances in genomics such as the release of whole genome reference sequence are offering opportunities for enhanced use of this species and its genetic resources. In this chapter, efforts were made to review current knowledge on O. longistaminata by addressing phenotypic and molecular studies conducted on this species. The use of advances in DNA sequencing in understanding the potential of this species and dissecting the molecular mechanism underlying various useful traits is highlighted.Item Oryza glaberrima Steud.(Book, 2018) Ndjiondjop M.N.; Wambugu P.; Sangare J.R.; Dro T.; Kpeki B.; Gnikoua K.Oryza glaberrima is the African cultivated rice species, domesticated from its wild ancestor by farmers living in Inland Delta of Niger River. Several studies indicated that it has extremely narrow genetic diversity compared to both its wild progenitor, Oryza barthii and the Asian rice, Oryza sativa which can mainly be attributed to a severe domestication bottleneck. Despite its scarcity in farmer's field due to its low yield potential, high shattering and lodging susceptibility, O. glaberrima is of great value not only to Africa but also globally. Perhaps its greatest contribution to regional and global food security is as a source of genes, as it possesses resistance/tolerance to various biotic and abiotic stresses. It also has unique starch-related traits which give it good cooking and eating properties. Advances in DNA sequencing have provided useful genomic resources for African rice, key among them being whole genome sequences. Genomic tools are enabling greater understanding of the useful functional diversity found in this species. These advances have potential of addressing some of the undesirable attributes found in this species which have led to its continued replacement by Asian rice. Development of new generation of rice varieties for African farmers will therefore require the adoption of advanced molecular breeding tools as these will allow efficient utilization of the wealth and resilience found in African rice in rice improvement.Item Evolutionary Relationships Among the Oryza Species(Book, 2018-02-16) Wambugu P.W.; Nyamongo D.; Ndjiondjop, M.N.; Henry R.J.Despite being highly studied, the evolutionary relationships in the Oryza genus have remained inconsistent and inconclusive. The origin and domestication history of Asian rice has particularly remained contentious. This chapter discusses the evolutionary relationships between various species in the Oryza genus, with a special focus on the application of current advances in genomics in understanding the various evolutionary dynamics. Advances in genomics are offering opportunities for resolving the origin of cultivated rice and clarifying phylogenetic and evolutionary relationships between the various Oryza species. Analysis of genomes of cultivated rice and their putative progenitors is providing useful information such as unusually diverged genomic regions, which provides vital insights into rice evolution, domestication and demographic history. However, with the increase in whole genome sequence data, it appears that data analysis and subsequent interpretation may now present the next challenge in efforts aimed at resolving this hot debate. The use of nuclear and whole chloroplast genome sequences is helping define the relationships between the recent newly discovered Australian taxa which are believed to be novel gene pools. In this chapter, we have also discussed the challenges faced in efforts aimed at resolving evolutionary relationships in the Oryza genus.