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Prospects for cereal self-sufficiency in sub-Saharan Africa
No full textSub-Saharan Africa (SSA) has the world’s largest projected increase in demand for food. Increased dependence on imports makes SSA vulnerable to geopolitical and economic risks, while further expansion of agricultural land is environmentally harmful. Cereals, in particular, maize, millet, rice, sorghum, and wheat, take nearly 50% of the cropland and 43% of the calories and proteins consumed in the region. Demand is projected to double until 2050. Here, we assess recent developments in cereal self-sufficiency and provide outlooks until 2050 under different intensification, area expansion, and climate change scenarios. We use detailed data for ten countries. Cereal self-sufficiency increased between 2010 and 2020 from 84 to 92% despite the 29% population increase. The production increase was achieved by increased yields per hectare (44%), area expansion (34%), and a shift from millet to the higher yielding maize (22%). Outlooks for 2050 are less pessimistic than earlier assessments because of the larger 2020 baseline area, higher shares of maize and somewhat less steep projected population increase. Yet, to halt further area expansion, a drastic trend change in annual yield increase from the present 20 to 58 kg ha−1 y−1 is needed to achieve cereal self-sufficiency. While such yield increases have been achieved elsewhere and are feasible given the yield potentials in SSA, they require structural changes and substantial agronomic, socioeconomic, and political investments. We estimate that amounts of added nitrogen need to at least triple to achieve such yield improvements, but it is essential that this comes with improved context-specific agronomy
Climate change vulnerability and drivers of low maize yields under smallholder farming systems in semi‑arid area of Marange in Zimbabwe
No full textIn semi-arid regions, smallholder farmers are vulnerable to the impacts of climate change due to naturally low rainfall. However, regardless of their vulnerability, farmers continue to grow maize (Zea mays L.) under rain-fed systems even though the chances of crop failures are very high, and their yields remain extremely low. This study used on-farm data to investigate how agronomic management practices chosen by farmers influence maize productivity in rain-fed smallholder farming systems in the semi-arid Marange area of Mutare district, Zimbabwe. A sample of 107 farmers were interviewed at household level. The collected information included socio-ecological data and maize yield data from small plots on each farm of an interviewed household. The results showed extremely low maize yields, ranging from 90 to 970 kg ha−1 and an average of 355 kg ha−1. Several agricultural practices, including the strategic choice for where to plant the maize, the use of planting basins, weed management, and mulching, contributed to differences in maize yields among households. Socio-economic factors including access to agricultural information (market- and production-related), weather information services, and exposure to extension officers and researchers, enabled farmers to learn and achieve better maize yields. We conclude that maize yields are still terribly low, requiring additional efforts to develop measures that improve the production in these vulnerable communities. While most of the selected agronomic practices showed significant differences, overall yields were still low. A comprehensive overhaul of agronomic practices, land management practices, extension services, and access to weather and climate information is needed to sustainably improve maize productivity in smallholder farming systems vulnerable to climate variability and change
A retrospective analysis of maize performance under low nitrogen stress conditions in sub-Saharan Africa
No full textIntroduction: Fertilizer use in sub-Saharan Africa (SSA) is the lowest in theworld and has stagnated. Consequently low nitrogen (N) stress is one of the principal constraints to maize yields in this region. Therefore improving nitrogen use efficiency of maize varieties will result in higher nitrogen recovery rates, leading to less leaching of nitrogen as well as loss through nitrification and ammonification. This study aimed to: 1) Investigate the relationship between grain yield under low N and optimal conditions; and 2) Establish the level of variability in low N tolerance among elite Eastern and Southern African (ESA) maize varieties. Methods: Fifty-eight paired trials, each consisting of 40 to 65 maize hybrids, were conducted under low N and optimal (i.e.,high N) conditions in five countries, in Eastern and Southern Africa during 2013-2015. Results and discussion: The level of yield reduction as a result of low N stress ranged from 8% to 91% across the 58 paired trails. Grain yield of hybrids ranged from1.69Mg ha-1 to 3.44 Mg ha-1 in the early maturity group and 1.71 Mg ha-1 to 3.35 Mg ha-1 in the intermediate to late maturity group, with heritability ranging from 0.25 to 0.53 and 0.29 to 0.76, in the respective two maturity groups. Under the low N stress. Pre-commercial hybrids that were bred for low N tolerance performed better than the old commercial hybrids and open pollinated varieties (OPVs). These results suggest that if more effort is devoted to selecting maize under low N conditions, significant yield gains can be realized with profound impact on maize productivity in SSA
Harnessing phosphocompost extracts to mitigate Meloidogyne javanica impacts on tomato
No full textThis study evaluated the chemical properties of phosphocompost extracts and their effectiveness in inducing tomato seedlings resistance to Meloidogyne javanica. Phosphocomposts: Sugar beet phosphocompost (PC-SB: CP2), green waste phosphocompost (PC-GW: CP3), and olive mill waste phosphocompost (PC-OMW: CP4), were utilized to produce compost water extracts at concentrations of 1:5, 1:10, 1:20, and 1:100 g:mL and then applied as soil drenches for tomato seedlings one-week post-inoculation. The CP2 extract applied at a 1:5 dilution led to marked improvements in growth parameters, with plant height increasing by over 52.2%, shoot fresh biomass rising by approximately 52.44%, and shoot dry biomass showing a gain of 62.21%. Root biomass also rose by 33%. Chlorophyll a increased with CP4 at 1:5 and 1:100 (41.05% and 37.32%), chlorophyll b increased with CP3 at 1:5 and 1:10 (22.34% and 7.59%), while carotenes showed no variation. Polyphenols rose by 86.45-91.01% with CP2 from 1:5 to 1:20, and flavonoids increased by 64.90% with CP4 at 1:10. CP2 diminished the ultimate M. javanica population and reproduction factor by 171.43%, while CP4 at 1:20 decreased egg masses by 151.94%. The root gall index showed no variation. The chemical composition of phosphocomposts revealed that the strategic incorporation of diverse organic improvers (10%) in phosphocomposts yielded distinct nutrient signatures, with sugar beet waste enhancing PO43- (12.91 mg/L) and secondary macronutrients, green waste optimizing NO3- (69.91 mg/L) and SO42- (62.70 mg/L) availability, and olive mill waste producing superior micronutrient concentrations alongside dominant Ca (24.21 mg/L), K (392.50 mg/L), and P (9.17 mg/L) levels. Overall, the results underscore the potential of phosphocompost extracts as a viable, low-cost, and eco-friendly alternative to synthetic nematicides, offering a sustainable and resilient approach to M. javanica control while enhancing tomato plant growth
Bridging the gap: Integrating crop pests and pathogens into agricultural foresight models for food security assessments
No full text979–98
Costing of the breeding operations for the national maize programs in Eastern and Southern Africa
No full textThe Genetic Innovation Initiative on Accelerated Breeding (ABI) of The Consultative Group on International Agricultural Research (CGIAR) has been supporting the costing of breeding operations for the CGIAR-National Agricultural Research and Extension Systems-Small to Medium Enterprises (CGIAR-NARES-SME's) crop breeding networks. The aim is to help these breeding programs to accurately estimate operational costs, develop precise budgets, set appropriate service fees, and choose the best technologies for increased genetic gains. Breeding programs are being guided in using the University of Queensland's open-source breeding costing tool (UQ-BPCT). This paper outlines the costing strategy and demonstrates the tool's utility using data from national breeding programs in Uganda (NARO), Zambia (ZARI), and Zimbabwe (DR&SS). Results show that the percentage of budgets allocated to germplasm development ranged from 25% (DR&SS) to 52% (NARO), with conventional methods costing 7 to 47 times more than doubled haploids. Costs for trials varied, with ZARI spending 14% and DR&SS spending 51%. In one breeding cycle, NARO released 5 hybrid varieties, ZARI 2, and DR&SS 1. The programs can be optimized by implementing several strategies: adopting an Enterprise Breeding System, incorporating digital technologies for disease screening and phenotyping, network-based procurement of consumables, using modern breeding techniques like doubled haploids, genomic selection, and speed breeding to shorten cycles, and training personnel for more efficient resource use
Modelling the climate change adaptation potential of no-tillage maize systems in southern Africa
No full textSouthern Africa is a hotspot of climate change where smallholder farmers are particularly threatened because they largely depend on rainfed agriculture for their livelihoods. The objective of the study was to assess the potential of two main principles (no-tillage and crop residue retention) of conservation agriculture (CA) and nitrogen (N) fertilizer management to mitigate the negative effects of future climate (2021–2060) on maize (Zea mays L.) productivity using the Agricultural Production Systems Simulator (APSIM). Two tillage practices were considered in the simulations, i.e. the conventional practice of tillage with removal of crop residues (CP) and NT (no-tillage and crop residue mulching), as well as three rates of N input (0, 30, 90 kg ha−1) on mono-cropped continuous maize. Simulations were run for future climate generated by an ensemble of 17 global circulation models (GCMs) using two extreme emission scenarios based on Representative Concentration Pathways (RCP2.6 and RCP8.5) for southern Africa. Results from the simulations suggest that NT management is not more beneficial in the future (2051–2060) than in the current climate, and there is no evidence to support its ability to mitigate the climate change impacts at the study sites, because the effects are principally exerted through increased temperatures. Simulations further show that increased fertilizer N inputs could drastically increase maize productivity, but with increased vulnerability to climate change. Improved crop management practices such a NT need to be combined with improved crop genotypes tolerant to multiple stresses such as drought and heat to maximize resilience under future climatic conditions
A review of organic inputs to inform soil health advice for African smallholder farmers: localization matters
No full textAfrican smallholder farming systems are complex, diverse and locally adapted, but guidance is lacking on how farmers can make informed choices of the type of organic inputs to suit their farm conditions. In this review we aimed to provide a synthesis of actionable information on ex situ and in situ organic resources and decision support tools to facilitate evidence-based choices by smallholders in cereal production systems in sub-Saharan Africa
Fall armyworm (Spodoptera frugiperda) in Africa: insights into biology, ecology and impact on staple crops, food systems and management approaches
No full textThe fall armyworm (FAW), Spodoptera frugiperda, is a polyphagous pest native to the American continent that was first detected in Africa in 2016, where it has since become a major constraint to agriculture. This species severely damages staple crops like maize, sorghum, and rice, threatening food security and the livelihoods of millions of smallholder farmers. Maize, the most vulnerable crop in sub-Saharan Africa, suffers significant annual losses due to the destructive impact of FAW, which affects agricultural productivity and overall rural economies. The pest displays complex biological and ecological patterns that are highly dependent on environmental factors, host plant availability, and natural enemy diversity, making control efforts challenging. This review explores the traits driving FAW's invasive success in Africa, summarizing key findings on its biology and ecology while outlining current management strategies. It underscores the importance of Integrated Pest Management (IPM), which includes cultural practices, biological control, mechanical/physical methods, host plant resistance, and judicious application of chemicals. Regular crop monitoring and surveillance principles are also discussed as prevention and early detection measures to mitigate FAW damage. Future directions emphasize the need for collaboration among stakeholders, including international research organizations, to effectively control FAW invasion. Given the economic risks of the FAW outbreak in Africa, adopting IPM solutions is crucial for reducing pesticide reliance and ensuring stable agricultural production. This review offers valuable insights into achieving this goal
Global transcriptomic analysis of inbred lines reveal candidate genes for response to maize lethal necrosis
No full textMaize lethal necrosis (MLN) is a significant threat to food security in Sub-Saharan Africa (SSA), with limited commercial inbred lines displaying tolerance. This study analyzed the transcriptomes of four commercially used maize inbred lines and a non-adapted inbred line, all with varying response levels to MLN. RNA-Seq revealed differentially expressed genes in response to infection by maize chlorotic mottle virus (MCMV) and sugarcane mosaic virus (SCMV), the causative agents of MLN. Key findings included the identification of components of the plant innate immune system, such as differentially regulated R genes (mainly LRRs), and activation/deactivation of virus resistance pathways, including RNA interference (RNAi) via Argonaute (AGO), Dicer-like proteins, and the ubiquitin–proteasome system (UPS) via RING/U-box and ubiquitin ligases. Genes associated with redox signaling, WRKY transcription factors, and cell modification were also differentially expressed. Additionally, the expression of translation initiation and elongation factors, eIF4E and eIF4G, correlated with the presence of MLN viruses. These findings provide valuable insights into the molecular mechanisms of MLN resistance and highlight potential gene candidates for engineering or selecting MLN-resistant maize germplasm for SSA