In a groundbreaking shift that revises fundamental biological paradigms, a research team led by Dr. Amiran Khabidovich Zanilov at the Center for Decarbonization of the Agro-Industrial Complex and Regional Economy, Kabardino-Balkarian State University, has uncovered a previously unrecognized mechanism of carbon dioxide (CO₂) exchange occurring in plant root systems. Challenging the conventional wisdom that roots merely respire CO₂ as a metabolic byproduct, this innovative experimental study demonstrates that roots can actively absorb CO₂ from the soil environment, a process intricately modulated by external factors such as light regimes, fertilizer application, and atmospheric CO₂ concentrations.
The investigation employed an advanced experimental setup featuring hermetically sealed chambers for both the aerial and subterranean parts of maize plants, integrated with high-precision CO₂ sensors capable of real-time monitoring of gas fluxes. By maintaining stringent environmental control and isolating CO₂ exchange dynamics within the soil–plant–atmosphere continuum, the study offers unprecedented insights into how carbon partitioning within plants is influenced by external stimuli over a 40-day observational period involving 19 plants.
Day-night cycles emerged as a crucial determinant in root behavior. Under the natural light-dark transitions of ‘Mode A’, researchers observed a compelling inverse relationship between CO₂ concentrations in leaf and root chambers (correlation coefficient r = -0.859). As photosynthesis dwindled with the onset of darkness, CO₂ levels in leaves increased due to halted carbon fixation, while the root chambers showed a sharp decline in CO₂ concentration. This phenomenon indicates that roots switch roles from being net emitters to active consumers of soil CO₂, particularly during daylight hours when atmospheric CO₂ hovers within a physiologically relevant range of 367 to 417 parts per million.
Such findings suggest an alternative carbon nutrition pathway that had previously been overlooked. Dr. Zanilov postulates that roots may act as supplemental carbon sinks, scavenging available CO₂ when photosynthetic activity in leaves diminishes, thereby contributing to overall plant carbon homeostasis. This nuanced carbon uptake by roots introduces a potentially vital mechanism for buffering plants against fluctuations in atmospheric CO₂—a factor that could be pivotal in adapting to climate variability.
The interplay between nutrient availability and carbon absorption was probed under ‘Mode B’ by administering ammonium nitrate fertilizer, a standard agricultural input. Contrary to expectations that nitrogen enrichment facilitates enhanced photosynthetic carbon fixation, the data revealed a complex response: the plants exhibited elevated nighttime leaf respiration rates alongside a notable decrease in daytime CO₂ uptake, with absorption dropping from baseline levels of 70.4 ppm to 92.3 ppm in fertilized specimens. This paradox highlights a metabolic trade-off where nitrogen-induced metabolic acceleration temporarily impairs carbon fixation capability.
This revelation holds profound implications for agronomic practices. Fertilizer regimes, while essential for crop productivity, may inadvertently disrupt the delicate carbon assimilation balance. Strategic adjustment of fertilizer timing and quantity could optimize photosynthetic efficiency and carbon uptake, ultimately bolstering yield resilience and ecological sustainability.
Light intensity further influenced carbon flux dynamics, addressed in the third experimental mode. Doubling illumination from 1750 to 3500 lux produced a delayed respiratory response post-photoperiod cessation. Specifically, CO₂ release in leaf chambers was postponed by approximately 80 minutes following lights-off, indicating that plants subjected to higher light intensities possess enhanced stores of energy-rich compounds or carbon intermediates. This metabolic reservoir appears to sustain cellular respiration beyond light availability, akin to an organic battery that prolongs physiological function after photosynthesis ends.
This delayed respiratory activation underscores plants’ ability to modulate internal carbon and energy fluxes in response to environmental lighting conditions, which could influence growth and stress responses under variable light environments—a consideration critical for controlled agricultural settings such as greenhouses.
Under conditions simulating elevated atmospheric CO₂ (‘Mode D’), root CO₂ uptake was completely inhibited when leaf chamber concentrations rose from 500 to 1500 ppm. The root-soil CO₂ concentration gradient, which drives passive diffusion and active uptake, was reversed, effectively halting root scavenging activities. This finding portends significant consequences in light of global climate change, where rising CO₂ levels could diminish the efficacy of root-mediated carbon assimilation pathways unless plants undergo adaptive physiological shifts.
Such a potential feedback mechanism could alter global carbon cycling models by reducing terrestrial carbon sinks’ efficiency. The study emphasizes the necessity to incorporate root-level CO₂ dynamics into climate models and carbon budget assessments to improve predictions of ecosystem responses to escalating atmospheric CO₂.
Beyond ecological and climatological ramifications, these results challenge textbook definitions of root metabolism. Historically, plant roots have been regarded primarily as heterotrophic organs that contribute CO₂ to the soil through respiration. This investigation compels a paradigm shift, recognizing roots as dynamic participants in both carbon emission and carbon sequestration, with their role contingent on environmental and physiological contexts.
The integration of soil, root, and atmospheric interactions revealed herein opens new research avenues into plant-soil carbon interchanges, especially concerning agricultural systems. By refining our understanding of how light intensity, nutrient supply, and atmospheric composition regulate plant carbon economy, scientists and agronomists can better tailor management practices to enhance carbon capture and improve crop resilience.
Kabardino-Balkarian State University’s Center for Decarbonization stands at the forefront of this emerging field, blending ecological theory with engineering advancements to solve pressing carbon cycle challenges. Dr. Zanilov’s team exemplifies how focused, regionally based research initiatives can yield insights with global significance, emphasizing the value of innovative experimentation on even the most well-studied organisms.
This discovery redefines roots not just as passive conduits at the base of plants, but as active, responsive organs integral to carbon cycling and global carbon management. As we deepen our investigation of belowground physiology, we unlock new dimensions of plant life previously obscured, enhancing our capacity to steward ecosystems in a rapidly changing world.
Next time you walk through a cornfield, consider that beneath the surface, a silent carbon exchange is underway — one that holds the promise to reshape our understanding of plant biology and the carbon cycle.
Article Title: Influence of external factors on the behavior of CO2 in the root system of plants in a model experiment
News Publication Date: 17-Oct-2025
Web References:
- Journal: Carbon Research
- DOI: 10.1007/s44246-025-00237-1
References:
Dudarov, Z.I., Zanilov, A.K., Altudov, Y.K., et al. Influence of external factors on the behavior of CO₂ in the root system of plants in a model experiment. Carbon Res. 4, 66 (2025).
Image Credits:
Credit: Zalim Islamovich Dudarov, Amiran Khabidovich Zanilov, Yuri Kambulatovich Altudov & Yuri Khasanovich Shogenov
Keywords:
Carbon dioxide; CO₂; Gas Analyzer; Photosynthesis; Root carbon nutrition of plants
