Substrate-mediated oxidative stress alleviation and rhizosphere microbiome modulation enable submerged macrophyte restoration in high-turbidity water

Introduction Ecological restoration of submerged macrophytes in highly turbid waters is severely hampered by light attenuation, which imposes significant oxidative stress on plants and disrupts their physiological homeostasis. While suspended planting technology offers a solution by optimizing light exposure, the critical role of planting substrates in modulating plant stress tolerance and rhizosphere resilience remains largely unexplored—a knowledge gap that this study addresses for the first time. This study is novel in systematically linking substrate physical properties to plant redox regulation and rhizosphere microbiome assembly under turbid-water stress, providing an integrated plant–microbe perspective previously unaddressed. Methods In this study, we cultivated Vallisneria spinulosa Yan using four suspended substrates (plastic mesh, palm mat, linen cloth, and bamboo woven strips) in outdoor flume experiments, aiming to evaluate their effects on plant physiology, water remediation, and associated microbial networks. Results Our results demonstrated that the linen cloth substrate most effectively alleviated oxidative damage, as evidenced by significantly enhanced root development, biomass accumulation, and leaf photosynthetic pigment content, alongside a marked reduction in physiological oxidative stress markers. Functionally, all treatments achieved over 90% turbidity removal; however, the linen cloth group exhibited superior purification efficiency, with the highest total nitrogen and total phosphorus removal loads (2.32 × 10 -4 and 2.70 × 10 -4 g·m -2 ·d -1 , respectively). Critically, microbial community analysis revealed that the linen cloth substrate fostered a more complex and interconnected rhizosphere network, with a notable enrichment of a denitrifying bacterial family ( Comamonadaceae ), indicating a synergistic enhancement of plant–microbe mutualism under stress. Discussion Collectively, our findings identify linen cloth as the optimal substrate for suspended planting, not merely as a physical support, but as a catalyst for reinforcing the plant’s antioxidant defense system and orchestrating a beneficial rhizosphere microbiome, thereby providing a robust theoretical framework for applying this redox-based ecological engineering strategy in turbid water restoration.