Effect of Elevated Carbon Dioxide on the Growth and Development of C3 and C4 Functional Groups

Authors: KAUR, NAVNEET - Mississippi State University; THENVEETTIL, NAFLATH - Mississippi State University; SEHGAL, AKANKSHA - Mississippi State University; BHEEMANAHALLI, RAJU - Mississippi State University; Reddy, Krishna; GAO, WEI - Colorado State University; REDDY, RAJA - Mississippi State University

Submitted to: Frontiers of Earth Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2025
Publication Date: 12/15/2025
Citation: Kaur, N., Thenveettil, N., Sehgal, A., Bheemanahalli, R., Reddy, K.N., Gao, W., Reddy, R.K. 2025. Effect of Elevated Carbon Dioxide on the Growth and Development of C3 and C4 Functional Groups. Frontiers of Earth Science. https://doi.org/10.1007/s11707-025-1178-6.
DOI: https://doi.org/10.1007/s11707-025-1178-6

Interpretive Summary: The CO2 concentration in the atmosphere is rising and plant growth and developmental responses to an increase in CO2 may depend on plant functional groups such as C3 or C4 groups or monocots or dicots. Scientists from Mississippi State University, Mississippi Sate, Mississippi; USDA-ARS, Crop Production Systems Research Unit, Stoneville, Mississippi; and Colorado State University, Fort Collins, Colorado have investigated response of five crop species belonging to two functional groups represented by one plant species, C3 dicot (cotton), C3 monocot (wheat), nodule-forming and nitrogen-fixing C3 dicot (soybean), C4 monocot (sorghum), and a C4 dicot (Amaranthus). C3 species, mainly cotton and soybean, exhibited significant increases in leaf area, shoot dry weight, and total biomass under elevated CO2, while C4 species showed minimal response. The overall micro- and macro-nutrient composition of leaves decreased under elevated CO2, with notable exceptions in zinc for Amaranthus and copper for wheat. The results showed that C3 plants, mainly dicots, are more responsive to increases in CO2, likely due to their photosynthetic mechanism, while C4 plants showed limited or no response. The study highlights the varying responses of different functional groups to increasing CO2 and emphasizes potential challenges for the nutrient quality of crops in the future.

Technical Abstract: The concentration of CO2 ([CO2]) in the atmosphere has been rapidly increasing over recent decades and is projected to reach 1000 ppm by 2100. This rise in [CO2] has the potential to impact plant growth and development. Different functional groups of plants have been suggested to respond differently to increases in [CO2]. In this study, we investigated five crop species belonging to two functional groups represented by one plant species, C3 dicot (cotton), C3 monocot (wheat), nodule-forming and nitrogen-fixing C3 dicot (soybean), C4 monocot (sorghum), and a C4 dicot (Amaranthus). We hypothesized that the C4 functional groups will saturate at current CO2 levels while C3 plants will continuously respond positively to increased [CO2]. The five plant species were grown in sunlit plant growth chambers under six [CO2] ranging from 320 to 820 ppm in 100 ppm increments for 34 days. C3 species, mainly cotton and soybean, exhibited significant increases in leaf area (74%), shoot dry weight (87%), and total biomass under elevated CO2, while C4 species showed minimal response. Root weight and root-by-shoot ratio of all the crops except cotton (69% increase in root weight) were unaffected by increases in [CO2]. The overall micro- and macro-nutrient composition of leaves decreased under elevated [CO2], with notable exceptions in zinc for Amaranthus and copper for wheat. The results showed that C3 plants, mainly dicots, are more responsive to increases in [CO2], likely due to their photosynthetic mechanism, while C4 plants showed limited or no response. The study highlights the varying responses of different functional groups to increasing [CO2] and emphasizes potential challenges for the nutrient quality of crops in the future.