Rhizosphere nutrient dynamics and physiological responses of Oryza sativa L. under polyethylene terephthalate...

Polyethylene terephthalate microplastics (PET-MPs), as emerging environmental contaminants, pose growing threats to agricultural ecosystems. This study investigated the impacts of PET-MPs on key physiological traits of Oryza sativa L. and the abundance of functional genes involved in carbon (C), nitrogen (N), and phosphorus (P) cycling within rhizosphere soils. Results demonstrated that PET-MPs were absorbed by rice roots and translocated to aerial tissues, significantly inhibiting chlorophyll biosynthesis (p < 0.05). Exposure to PET-MPs induced oxidative stress, with the 2.5 g kg^-1 treatment elevating root malondialdehyde levels by 175.3 %, and reducing plant height and biomass by 15.8 % and 44.6 %, respectively. Metagenomic analysis revealed a marked increase in the denitrification gene narI, while genes associated with C fixation (korB, korA), methanogenesis (mch), organic N metabolism (glnA), and P transport (ugpC) were significantly suppressed, indicating disruptions to soil nutrient cycling. Actinomycetota and Pseudomonadota were identified as predominant microbial hosts of these functional genes. Pearson correlation analysis showed significant positive associations (p < 0.05) between plant growth parameters and the abundance of korA, korB, IDH1, mch, glnA, and ugpC. These findings advance our understanding of the ecological risks posed by PET-MPs in terrestrial environments and underscore their potential to compromise soil fertility and sustainable rice production.