Background　and　aims　Although　the　role　of　microbial　iron　respiration　in　tidal　marshes　has　been　recognized　for　decades,　the　effect　of　rhizosphere　processes　on　dissimilatory　ferric　iron　reduction　(FeR)　is　poorly　known.　Herein,　we　examined　the　FeR　surrounding　the　root　zone　of　three　tidal　marsh　plants.　Methods　Using　in　situ　rhizoboxes,　we　accurately　separated　rhizobox　soil　as　one　rhizosphere　zone,　and　three　bulk　soil　zones.　Dissimilatory　and　sulfidic-mediated　FeR　were　quantified　by　accumulation　of　non-sulfidic　Fe(II)　and　Fe　sulfides　over　time,　respectively.　Results　The　rates　of　dissimilatory　FeR　attained　42.5　mu　mol　Fe　g(-1)　d(-1)　in　the　rhizosphere,　and　logarithmically　declined　by　up　to　19.1　mu　mol　Fe　g(-1)　d(-1)　in　the　outer　bulk　soil.　The　rates　of　sulfidic-mediated　FeR　were　less　than　2　mu　mol　Fe　g(-1)　d(-1)　among　all　zones.　Poorly　crystalline　Fe(III),　DOC　and　DON,　porewater　Fe2+,　and　SO42-　were　all　enriched　in　the　rhizosphere,　whereas　non-sulfidic　Fe(II)　and　Fe　sulfides　gradually　accumulated　away　from　the　roots.　Iron　reducers　(Geobacter,　Bacillus,　Shewanella,　and　Clostridium)　had　higher　populations　in　the　rhizosphere　than　in　the　bulk　soil.　Higher　rates　of　dissimilatory　FeR　were　observed　in　the　Phragmites　australis　and　Spartina　alterniflora　rhizoboxes　than　in　the　Cyperus　malaccensis　rhizoboxes.　Conclusions　The　radial　change　pattern　of　dissimilatory　FeR　rates　were　determined　by　allocation　of　poorly　crystalline　Fe(III)　and　dissolved　organic　carbon.　The　interspecies　difference　of　rhizosphere　dissimilatory　FeR　was　associated　with　the　root　porosity　and　aerenchyma　of　the　tidal　marsh　plants.