【Objective】Carbon cycling in paddy soils is crucial for carbon sequestration and soil fertility enhancement. The rice root zone, being the most active site of this cycle, exhibits carbon turnover processes that are closely linked to soil redox conditions and iron phase transformations. However, the iron-mediated organic carbon mineralization process under redox gradients remains unclear, and the carbon-iron coupling mechanism requires systematic elucidation.【Method】In this study, it is established a simplified rhizosphere microcosm system by using soil columns equipped with artificial roots. Four redox potential gradients of the soil column were constructed by adjusting water conditions (60%, 80%, and 100% of soil water saturation capacity, plus 3 cm flooding), and ¹³C-labeled glucose was used as a model root exudate, for investigating the effects of iron phase transformation on total organic carbon mineralization and priming effect in the root zone under different redox states.【Result】The results showed that: (1) Both soil Eh reduction and exogenous glucose input significantly increased the cumulative emissions of CH₄ and CO₂. Under water-saturated conditions, the incremental emission of CH₄ was significantly higher than that of CO₂ in the glucose-amended treatments, and vice versa in the unsaturated water content. (2) In both glucose-amended and non-amended treatments, soil dissolved organic carbon (DOC) content generally decreased compared to pre-incubation levels, but the aromaticity of DOC increased under saturated conditions. Eh reduction and glucose input stimulated ferrous iron (Fe²⁺) reduction and iron-associated organic carbon (Fe-OC) release, with Fe-OC content variations showing significant correlations with iron speciation and CO₂ emission rates. (3) The activities of carbon cycle hydrolase and oxidase were significantly affected by the redox gradient and glucose input. Cellobiohydrolase (CBH) activity decreased with decreasing Eh and showed a negative correlation with CH₄+CO₂ emission rates. Moreover, phenol oxidase activity was higher in the saturated water treatments than in the unsaturated water treatments and was positively correlated with the rate of gas emission. Glucose addition significantly increased the activities of phenol oxidase and catalase oxidase. 【Conclusion】Both the “iron gate” and “enzyme latch” mechanisms synergistically regulated CH₄ and CO₂ emissions. The findings provide critical parameters and a scientific basis for predicting rhizodeposited carbon sequestration potential in subtropical iron-rich paddy soil, and optimizing water management strategies to enhance carbon storage and mitigate greenhouse gas emissions in rice cultivation systems.