Current impacts of elevated CO2 on crop nutritional quality: a review using wheat as a case study

Abstract

This review synthesises current research findings and modelling approaches to explore the impact of elevated atmospheric carbon dioxide (eCO₂) concentrations on crop productivity, water and nutrient use efficiency, plant nutritional quality, and the implications for global food security. Over recent decades, rising atmospheric CO₂ levels have sparked significant concern due to their role in driving climate change. While some studies highlight the potential benefits of eCO₂, such as increased crop yields and improved water-use efficiency, many recent investigations reveal a concerning decline in crop nutritional quality. eCO₂ has been shown to reduce concentrations of key nutrients, including nitrogen, minerals, vitamins, polyphenols, and other non-nutrient compounds, as well as alter gene expression. These changes are further complicated by interactions with heat stress and drought, presenting significant challenges in predicting sustainable future crop productivity. These nutritional declines exacerbate the global crisis of malnutrition and hidden hunger, threatening the achievement of Sustainable Development Goal 2 (SDG2), which aims to end hunger and ensure food security. Addressing these challenges requires further research, interdisciplinary collaboration, and innovative approaches to mitigate the adverse effects of eCO₂ on crop physiology and nutritional content while maximising agricultural sustainability. This review aims to provide insights into the complex mechanisms governing crop responses to eCO₂ using wheat as a model and proposes pathways for future research and agricultural practices. These strategies are critical for tackling the intricate dynamics of climate variability, ensuring nutrient-rich food production, and securing food security in the face of a rapidly changing climate.

Keywords: Climate change; Crop nutrients; Elevated carbon dioxide; Food security; Nutrition; Photosynthesis; Wheat; eCO2.

Fig. 1

Comparison of C3 and C4 photosynthetic pathway—in C3 plants, CO₂ fixation occurs directly via RuBisCO, forming a three-carbon compound in the Calvin cycle while C4 plants employ an initial CO₂ fixation step in mesophyll cells, producing a four-carbon compound that is transported to bundle sheath cells, and CO₂ is concentrated around RuBisCO to enhance photosynthetic efficiency and reduce photorespiration

Fig. 2

Bar plot showing global mean temperature difference from 1900 to 2020. Data culled from the National Oceanic and Atmospheric Administration (NOAA), NASA’s Goddard Institute for Space Studies (GISS) and the Berkeley Earth observation dataset (2023) (GISTEMP ; Lenssen et al. ; Rohde et al. ; Zhang et al. 2019)

Fig. 3

Summary of the effect of eCO2 on crops and its counter interactions with drought and heat stress

Fig. 4

Comparison of the number of experimental studies reporting the quantitative effect of eCO₂ on yield or nutritional compositions of wheat crop by the change in percentage (%) following a comprehensive literature inquiry conducted on Web of Science, Scopus and PubMed in February 2024. The sizes of the bubbles are equivalent to the number of studies, and the colour depicts the category of plant nutrients