- 1Soil Science, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
- 2Ecological Microbiology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
- 3Root-Soil Interaction, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
- 4Agroecology, Bayreuth Center of Ecology and Environmental Research (BayCEER), University of Bayreuth, Bayreuth, Germany
- 5Institute of Ecology, Chair of Soil Science, Technische Universität Berlin, Berlin, Germany
- 6Department for Geoscience and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
- 7Soil Biology Group, Department of Environmental Sciences, Wageningen University, the Netherlands
The symbiosis with arbuscular mycorrhizal fungi (AMF) can enhance the drought resilience of associated crops, for example, by modifying the belowground morphology of host plants. Additionally, the fungal symbionts are key drivers of organic matter (OM) allocation at the root-soil interface: AMF can modify the quantity and composition of plant-derived carbon (C) inputs to the soil and change their fate through altered microbial processing, enhanced organo-mineral interactions, or changes in spatial soil arrangements. However, the effects of future drought events on the intricate linkages between fungal symbionts, host plants, and their feedback on plant-derived OM dynamics under water scarcity remain poorly understood. This study aims to understand (1) how AMF, in conjunction with the host plant´s morphological response, influence plant-derived C inputs and their allocation across OM pools, and (2) whether AMF-mediated changes in the fate of plant-derived C differ between well-watered and drought conditions.
Two maize genotypes, an AMF-resistant mutant and an AMF-receptive wildtype, were grown in a pot experiment under well-watered and drought conditions. 13CO2 pulse labeling was employed to trace the allocation of assimilated C throughout the plant-soil system and across functional soil OM pools, which were isolated via density fractionation.
Drought strongly reduced 13C fixation of maize plants, limiting overall plant-derived C inputs to the soil and causing its accumulation in readily water-extractable forms. The fate of plant-derived C under both well-watered and drought conditions was modified by the symbiosis of the host plant with AMF: The greater compensatory root length growth of AMF-deficient plants promoted the occlusion of particulate OM in aggregates under well-watered conditions, whereas this effect did not prevail under drought. In contrast, the greater net-rhizodeposition of AMF-receptive plants facilitated the incorporation of plant-derived C into mineral-associated OM under both watering regimes, partially mitigating the drought-induced accumulation of plant-derived C in water-extractable form.
Our findings underscore the significant impact future drought spells will impose on plant-derived OM inputs and composition at the root-soil interface in cropping systems. Notably, the symbiosis of crop plants with AMF has the potential to enhance the persistence of root-derived OM in agricultural soils, not only under sufficient water supply but also during periods of drought.
How to cite: Steiner, F., Tyborski, N., Veciana, J., Abdalla, M., Lüders, T., Pausch, J., Mueller, C. W., and Vidal, A.: Symbioses with arbuscular mycorrhizal fungi alter allocation of plant-derived carbon to soil organic matter pools under drought and well-watered conditions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19311, https://doi.org/10.5194/egusphere-egu25-19311, 2025.
