Drought stress severely limits soybean productivity by impairing plant growth, water relations and nutrient acquisition. Iron (Fe) is an essential micronutrient involved in metabolic process in plants; however, its role in alleviating drought-induced physiological disruption in soybean remains understood. This study investigated the influence of Fe supplementation on soybean plants exposed to drought stress under controlled growth room conditions. Soybean plants were cultivated for eight weeks under four treatment conditions: control, drought, drought + Fe, and Fe+. Drought stress markedly reduced chlorophyll score, relative water content, shoot height, shoot biomass, root growth, and Fe-chelate reductase activity compared with control plants. Fe supplementation partially mitigated drought-induced growth inhibition by improving chlorophyll content, water status, shoot growth, root development, and nitrogen accumulation. Rhizosphere siderophore levels were significantly elevated in drought + Fe-treated plants, suggesting enhanced rhizosphere-mediated Fe mobilization under stress conditions. In contrast, excessive Fe treatment alone reduced chlorophyll content, nitrogen accumulation, and root growth despite increased Fe-chelate reductase activity. The findings demonstrate that appropriate Fe supplementation can alleviate drought-associated physiological impairment in soybean by improving nutrient acquisition and maintaining photosynthetic performance. This study highlights the importance of Fe homeostasis in drought adaptation and provides insights into nutrient-assisted strategies for improving soybean resilience under water-limited conditions.
