Rising CO2 levels: Impacts on crop nutrition and global food supplies

A recent study published in Engineering delves into the complex impacts of elevated CO2 levels on food security, plant growth, and crop quality. As the global atmospheric CO2 concentration continues to rise, understanding these effects is crucial for ensuring future food supplies.

On one hand, elevated CO2 can have some positive effects on plants. For C3 plants, it can stimulate photosynthesis, leading to increased dry matter yield and grain production. In legumes, it enhances N2 fixation, which is beneficial for reducing reliance on chemical fertilizers. Additionally, it can increase the water-use efficiency of plants by reducing stomatal conductance and transpiration.

However, the study also highlights numerous negative consequences. Elevated CO2 has been shown to decrease the nitrogen content in C3 crop species and C3 woody vegetation. This reduction in nitrogen affects the synthesis of proteins and amino acids in plants. For example, wheat grain protein has been found to decrease by 7.4% under elevated CO2, and the amino acid contents in various plant organs also decline.

Mineral nutrient contents in grains are also impacted. In rice and maize, the concentrations of phosphorus, sulfur, iron, zinc, copper, and manganese decrease under high CO2 levels. Overall, tissue mineral concentrations in C3 plants are predicted to drop by 8% while total non-structural carbohydrates increase.

These changes in crop composition pose significant threats to global food security. The decrease in grain protein, amino acids, and mineral nutrients could lead to a doubling of protein-calorie malnutrition and micronutrient deficiency, especially in regions like Africa where soils are nutrient-poor. Moreover, the increase in non-structural carbohydrates in cereal crops may elevate the incidence of diabetes due to high-starch diets.

To mitigate these negative effects, the researchers suggest several strategies. Selecting crop genotypes with superior biofortification traits for breeding programs could help alleviate nutrient deficiency. Planting more trees, especially N2-fixing C3 species, can sequester CO2 and improve soil fertility. Shifting to a more pulse-based diet can reduce methane emissions from livestock and also benefit from the high N2-fixing ability of legumes.

The study also points out the need for further research. Future studies should focus on the physiological and molecular responses of C3 plants to elevated CO2, analyze the metabolites involved in plant growth under such conditions, and assess the ecological impacts. Additionally, the application of artificial intelligence in plant breeding can help develop crop varieties more resilient to climate change and with improved nutritional quality.

The paper “Exploring the Impacts of Elevated CO2 on Food Security: Nutrient Assimilation, Plant Growth, and Crop Quality,” authored by Felix D. Dakora, Huihui Li, Jun Zhao. Full text of the open access paper: https://doi.org/10.1016/j.eng.2024.12.018. For more information about the Engineering, follow us on X (https://twitter.com/EngineeringJrnl) & like us on Facebook (https://www.facebook.com/EngineeringJrnl).

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