Investigating the impact of elevated CO2 on biomass accumulation and mineral concentration in foliar and edible tissues in soybean

Authors: KAUR, RAVNEET - Auburn University; DURSTOCK, MARY - Auburn University; Prior, Stephen; Runion, George; Ainsworth, Elizabeth; BAXTER, IVAN - Donald Danforth Plant Science Center; SANZ-SAEZ, ALVARO - Auburn University; LEISNER, COURTNEY - Auburn University

Submitted to: Plant Cell and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2025
Publication Date: 9/4/2025
Citation: Kaur, R., Durstock, M., Prior, S.A., Runion, G.B., Ainsworth, E.A., Baxter, I., Sanz-Saez, A., Leisner, C.P. 2025. Investigating the impact of elevated CO2 on biomass accumulation and mineral concentration in foliar and edible tissues in soybean. Plant Cell and Environment. 48:8712–8726. https://doi.org/10.1111/pce.70141.
DOI: https://doi.org/10.1111/pce.70141

Interpretive Summary: Rising atmospheric CO2 will likely increase photosynthesis and seed yield in soybean [Glycine max (L.) Merr.]. But breeding could change C uptake by leaves and seed nutrient levels under high CO2. This study looked at three cultivars under ambient and high CO2 atmospheric conditions. High CO2 reduced seed micronutrient concentrations, which was influenced by cultivar variation. The gene-environment interaction played a significant role by decreasing Zn and other nutrients in a cultivar that was previously thought to be non-responsive to high CO2. We propose that increased number of seeds, rather than increased per seed weight, reduced seed nutrient concentration due to mineral dilution. Additionally, high CO2 increased CO2 assimilation and biomass of leaves, stems, and seeds with little impact on root biomass. Roots likely could not compensate for increased CO2 uptake by enhancing nutrient absorption and transport, leading to reduced nutrients in seeds. Future research is needed to improve our understanding of the contributions of nutrient transport and absorption by roots under high CO2 conditions.

Technical Abstract: Rising atmospheric CO2 levels, projected to reach ~650 ppm by 2050, threaten the nutritional value of food crops. This rise is expected to increase biomass yield in C3 plants through enhanced photosynthesis and water-use efficiency. However, elevated CO2 (eCO2) reduces protein, nitrogen, and essential minerals like zinc (Zn) and iron (Fe) in plant leaves and seeds, posing a global nutrition risk. We conducted an experiment using Open Top Chambers (OTC) at the USDA-ARS National Soil Dynamics Laboratory in 2021, examining three soybean cultivars (Clark, Flyer, and Loda) under ambient (~410 ppm) and elevated (~610 ppm) CO2 conditions. Measurements of physiological parameters, biomass, and nutrient content were taken at different growth stages. Our results showed that eCO2 significantly increased carbon assimilation, leading to higher aboveground biomass and increased seed yield, which was driven primarily by increased seed number per plant. eCO2 also reduced stomatal conductance and transpiration, while root biomass remained unchanged. There was also a significant decrease in seed nutrient content at maturity, particularly Zn, Fe, P, K, and Mg, in plants grown in eCO2. These findings suggest that increased yield, reduced transpiration, and a lack of increase in root biomass (compared to aboveground biomass and seed yield) may be the main drivers of nutrient dilution in seeds in plants grown in eCO2.