Cara Griffiths, 22 December 2025

• In a recent article with collaborators, our CTO, Dr Cara Griffiths, provided her take on what traits are most important for improving crop performance in a changing climate.
• Attempts to enhance photosynthesis without boosting sink capacity struggle to deliver significant yield gains.
• Coordinating source and sink pathways – particularly during growth or reproductive development – offers a promising route to improving both crop yield and quality.

During the 20th century, crop yields increased dramatically when the Green Revolution tripled yield potential for staple crops such as wheat and rice. In this time, most yield gains came from changes in plant architecture, such as shorter stems leading to greater allocation of carbon into developing spikes.

With yield gains now plateauing, there has been a major push in academia over the last two decades to increase photosynthesis as a means of improving crop production. The logic is intuitive – more photosynthesis should mean more carbon for yield production.

In a recent effort with collaborators from Rothamsted Research, CIMMYT, and Nottingham University, we reviewed a body of scientific papers from decades of photosynthesis research and provided our take on what traits we should be chasing to improve crop performance in a changing climate. You can download our article in the 30^th Anniversary Issue of Trends in Plant Science.

We concluded that after gearing heavily on one side of the plant’s carbon economy, photosynthesis, we see growing evidence in the literature that source-sink interactions constrain the impact of that approach on yield improvement. The need to unlock this bottleneck is particularly interesting for our work at SugaROx, which we explore further in this blog.

Source-sink balance

Yield is not determined solely by how efficiently plants produce carbon, but by how effectively they can utilise it. For example, photosynthesis (the source of carbon) and crop growth or grain filling processes (the sink) are tightly connected through feedback loops. When sink processes are unable to use carbon due to other resource constraints, such as water or nitrogen availability, photosynthesis is reduced. Put simply, plants will only photosynthesise at high rates when there is demand for carbon. This means that attempts to enhance photosynthesis without boosting sink capacity struggle to deliver significant yield gains.

Timing of intervention matters

Increasing photosynthetic rate increases demand for other resources – water being a good example. While yield gains can be demonstrated in academic studies conducted under controlled glasshouse conditions, these gains frequently fail to translate to real-world farming systems where higher transpiration rates require increasing water supply – a resource often limited in farming systems. For me, this shows that when photosynthesis is enhanced matters just as much as how. Sustained increases in photosynthesis throughout the crop lifecycle can exacerbate water loss. By contrast, targeting photosynthesis to key crop stages when sink processes are activated reinforces photosynthetic rates.

Yield quality is part of the same equation

For Triticum aestivum (bread wheat), yield increases are often accompanied by a dilution of grain protein content. The academic literature indicates that this trade-off arises when carbon supply and nitrogen assimilation become uncoupled. This implies that better source-sink balance might not only activate starch synthesis but also promote the synthesis of protein in the grain. This field of research is limited, and it’s one that I am particularly excited to explore at SugaROx. The first molecule in our pipeline of active ingredients for crop biostimulants can deliver a boost in protein content in wheat grains – this effect has been consistent across the field trials commissioned by us since launching the company.

Rethinking yield improvement

The key message from our review of the scientific literature on photosynthesis research is clear: coordinating source and sink pathways – particularly during growth or reproductive development – offers a promising route to improving both crop yield and quality. The first molecule in our pipeline is a proprietary version of trehalose-6-phosphate (T6P), a natural plant sugar that boosts sink processes through the inhibition of the famine-signalling enzyme SnRK1, a central regulator of plant metabolism. By modulating the enzyme’s activity, we can strengthen carbon sink and, in turn, boost source processes.

Interested in our approach? Join the SugaROx mission

At SugaROx, we’re committed to advancing the science of crop stimulation.

Through our B2B model, we collaborate with go-to-market partners who deeply understand farmers’ needs and practices, testing and delivering our solutions across key agricultural markets worldwide.

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