Scientists quantify the impact of boosting photosynthesis on crop yield

Scientists have developed a new model to predict the impact of enhancing biological plant processes, such as photosynthesis, on large-scale crop yields. According to the new study, published on 8 April in Nature Plants, the effects varied from a reduction in crop yields of one per cent to an increase of 12 per cent, depending on environmental conditions ― for example, dry versus wet ― and different photosynthetic manipulations (1).

Thus, while boosting photosynthesis can potentially improve crop yields, the authors also show that increasing yields by enhancing a particular process is not so black and white. Other important drivers of plant growth such as water and carbon dioxide are also critical in predicting crop productivity.

Engineering photosynthesis to increase crop productivity

Various strategies have been proposed to bolster global food security and promote sustainable agriculture for the future. Boosting photosynthesis is one of the main approaches scientists are hoping to exploit by manipulating biological pathways involved in this essential process.

Photosynthesis occurs in all living plants. The process captures carbon dioxide from the atmosphere that is then used by the plant to grow. Several studies have shown that engineering this critical process can indeed increase plant growth. However, crop type and environment are also important factors, in particular, the availability of water resources.

Therefore, the ability to quantify the potential impacts of implementing new technologies on crop yields in various environments will be equally important.

Modelling the impact

To this end, the researchers from the University of Queensland in Brisbane and the National Australian University in Canberra used a so-called cross-scale model to associate leaf photosynthesis with field crop performance. They used data of crop biomass and yields from field experiments performed on wheat and sorghum.

The researchers examined three different way of manipulating photosynthesis:

• Increasing Rubisco, an important enzyme involved in photosynthesis;
• Enhancing electron transport in the leaf;
• Improving the flow of carbon dioxide (CO2) through the leaf.

The model can predict exactly which photosynthetic manipulations will boost crop yields the most in realistic crop environments. In other words, environments where light, nitrogen, and water availability are also important drivers affecting crop yield. In particular, they looked at well-irrigated versus dry croplands.

By integrating models of both photosynthesis and crops the comprehensive model can connect these biological processes to the larger-scale effects like overall crop yield across the entire growing season ― linking “cross-scale” effects. For example, they found that enhancing photosynthesis in sorghum crops can, in fact, decrease yields in scenarios where water is limited.

The model has successfully unravelled the complex relationship between photosynthesis and crop productivity. The model effectively “bridges the prediction gap” between leaf photosynthesis and crop yield by addressing connections with crop growth and development dynamics, and their interactions with the prevailing environment throughout the crop life cycle,” the authors write.

The analysis will also help guide future efforts to implement similar strategies. The authors hope the new predictive tool can be used to find new ways of improving yields of important staple crops worldwide.

(1) Wu, A. et al. Quantifying impacts of enhancing photosynthesis on crop yield. Nature Plants (2019). DOI: 10.1038/s41477-019-0398-8