Manipulating source-sink relationships in food crops involves altering metabolic processes to optimize the allocation of carbohydrates and nutrients between growth and storage tissues to increase crop yields without additional farming inputs.
Favorable source-sink relations
The innovation of manipulating source-sink relationships in food crops builds on centuries of crop breeding aimed at optimizing how plants allocate carbohydrates and nutrients between their growth (source) and storage (sink) tissues. This approach focuses on breakthrough methods and technologies—such as genetic engineering, biotechnology, and advanced breeding techniques—that can accelerate and enhance this process. By improving photosynthetic efficiency and fine-tuning resource distribution, the innovation aims to boost the flow of energy to edible or economically valuable parts of the plant (such as grains or tubers), ultimately increasing crop yields without requiring additional farming inputs.
The innovation aims to address the challenge of low crop yields, particularly in regions where food insecurity is prevalent. By optimizing the source-sink relationship, it seeks to enhance the efficiency of resource allocation within plants, increasing edible yields without relying on additional inputs such as water, fertilizer, or land. Through reducing the need for external inputs, the innovation also addresses environmental problems caused by synthetic fertilizer production and application, such as greenhouse-gas emission, soil degradation and eutrophication.
What impact could it have?
Potential for transformative impact
high
This innovation is potentially a game changer because it addresses the fundamental problem of low crop yields through a biologically based intervention, which has the potential to significantly increase food production without requiring more land, water, or fertilizers.
Human health impact
medium
Improving favorable source-sink relationships in next generation crops is likely to have medium indirect benefits to human health. By increasing crop yields, it can improve food security and lower food prices, especially in regions where staple crops are essential. However, these impacts depend on crop selection and widespread adoption.
Environmental impact
medium - high
The environmental impacts are likely to be medium to high. By increasing crop yields without additional inputs, it can reduce the need for expanding agricultural land and reduce external inputs, tackling associated environmental consequences of fertilizer production.
Livelihood impact
medium
The impacts on livelihoods are likely to be medium. Increased crop yields can enhance food security, which may increase incomes for smallholders due to surplus sales. However, the benefits will depend on factors like access to markets, infrastructure, and support systems.
Socio-cultural impact
medium
The socio-cultural impacts of this innovation are likely to be medium. While the increased productivity from improved source-sink relationships could benefit smallholder farmers, there is a risk of power concentration in large agricultural corporations, particularly if the technology is patented or controlled by a few entities. Social acceptability may also be a barrier to uptake.
Equity impact
medium
The impact on equity is likely to be medium. Smallholder farmers, particularly in rural areas, stand to benefit from higher yields, which could improve food security and incomes. However, disparities in access to technology, resources, and education could mean that more empowered or wealthier farmers benefit disproportionately.
What factors influence scaling?
The innovation does not face any limitations in regards to bundling needs. However, bundling with other innovations focused on improving soil fertility and sustainable fertilization may allow for compounded positive impacts on the food system. It could also be bundled with biofortification to increase health benefits and food security.
The geographic scope of this innovation is global, with a primary focus on regions heavily dependent on staple crops like cassava, maize, rice, and wheat—particularly in sub-Saharan Africa, Southeast Asia, and South America.
The innovation is likely to be adopted by small-, medium-, and large-scale food system actors, although medium- and large-scale commercial producers may adopt the technology more readily due to greater resources and reduced risk.
The innovation is likely to be adopted by small-, medium-, and large-scale food system actors, although medium- and large-scale commercial producers may adopt the technology more readily due to greater resources and reduced risk.
The innovation is potentially medium to high in its disruptive impact. Input suppliers, particularly fertilizer value chains, may be disrupted due to decreased demand. It could additionally impact primary producers in changing their seed inputs, potentially requiring less external resources.
The Cassava Source-Sink Project (CASS)
The innovation may exacerbate inequalities if large-scale producers with better access to technology dominate its adoption, leaving smallholder farmers behind. Additionally, increased productivity could lead to market oversupply, potentially lowering commodity prices and impacting the income of vulnerable producers. Furthermore, reliance on biotechnology may create dependencies on specific input suppliers, shifting power dynamics in favor of large corporations.
Where is acceleration most needed?
Accelerator scores reflect the degree of action needed across eight key accelerators of change that can enable an innovation to scale. A higher score signals that greater effort and support are needed in that area to unlock uptake at scale. Click on each accelerator to see what’s been achieved and what still needs attention.
Building Trust
Building Trust
While building trust is crucial, many stakeholders already recognize the potential of this innovation. However, aligning all actors and adjusting regulatory frameworks may require significant coordination across various levels of governance.
Transforming Mindsets
Transforming Mindsets
Transforming mindsets is key, as this innovation involves genetic and biotechnological interventions that could face resistance, particularly among smallholder farmers, the public, and regulatory bodies.
Enabling Social License
Enabling Social License
Engaging stakeholders is important, and while this innovation has benefits for both large-scale and smallholder farmers, ensuring transparent communication and addressing concerns will be necessary for widespread adoption.
Ensuring Stable Finance
Ensuring Stable Finance
Stable financing exists in the form of international collaborations and government-backed research initiatives for certain projects, such as the Cassava Source-Sink project. However, greater investment could accelerate scaling.
Designing Market Incentives
Designing Market Incentives
Designing market incentives would help mitigate early-stage adoption risks, but this innovation is still nascent and may require tailored fiscal policies to incentivize uptake, particularly in developing regions.
Changing Policies and Regulations
Changing Policies and Regulations
Changing policies and regulations will be critical as gene-editing technologies are involved. Existing regulations may need revision to accommodate new crop varieties and ensure safe deployment.
Safeguarding Against Undesirable Effects
Safeguarding Against Undesirable Effects
While the innovation has a lower risk of adverse impacts, monitoring its long-term effects on ecosystems and food security, as well as developing independent oversight bodies, is recommended to address potential unintended consequences.
Developing Transition Pathways
Developing Transition Pathways
Developing transition pathways is essential for guiding the widespread adoption of source-sink modifications, ensuring equitable access to technologies, and addressing potential negative effects on smallholder farmers who may not be able to implement such innovations immediately.
Reference
The Cassava Source-Sink (CASS) project, https://cass-research.org/
Amarullah, A., Indradewa, D., Yudono, P., & Sunarminto, B. D. (2017). Effect of source-sink manipulation on yield and related yield components in cassava (Manihot esculenta Crantz). International Journal of Agricultural Research, Innovation and Technology, 6(2), 69–76. https://doi.org/10.3329/ijarit.v6i2.31708
Rosado-Souza, L., Yokoyama, R., Sonnewald, U., & Fernie, A. R. (2023). Understanding source–sink interactions: Progress in model plants and translational research to crops. Molecular Plant, 16(1), 96-121. https://doi.org/10.1016/j.molp.2022.11.015
Sonnewald, U., Fernie, A. R., Gruissem, W., Schläpfer, P., Anjanappa, R. B., Chang, S.-H., Ludewig, F., Rascher, U., Muller, O., van Doorn, A. M., Rabbi, I. Y., & Zierer, W. (2020). The Cassava Source–Sink project: Opportunities and challenges for crop improvement by metabolic engineering. The Plant Journal, 103(5), 1655–1665. https://doi.org/10.1111/tpj.14865
