Alterations of the rhizosphere soil microbial community composition and metabolite profiles of Zea mays by polyethylene-particles of different molecular weights.

Polyethylene film is the most widely used plastic film in agricultural production activities, and its depolymerization products are mainly polyethylene-particles (PE-particles) of different molecular weights. However, the impact of the molecular weights of the PE-particles on soil-crop microenvironment has not been elucidated. In this study, a potted microcosmic simulation system was used to evaluate the impact of low, medium and high molecular weight PE-particles on soil metabolism, microbial community structure, and crop growth. There were obvious differences in the shape and surface microstructure of PE-particles with different molecular weights. Soil sucrase and peroxidase had significant responses to PE-particles of different molecular weights. In the rhizosphere, the number of microorganisms and the microbial alpha diversity index increased with increasing PE-particles molecular weight. Rhizobacter, Nitrospira, and Sphingomonas were the dominant microorganisms induced by PE-particles to regulate the metabolism of elements. Carbohydrate and amino acid contents in rhizosphere soils were the key factors affecting the species abundance of Lysobacter, Polyclovorans, Rhizobacter, and Sphingomonas. In plants, PE-particles treatment reduced the plant biomass and photosynthetic rate and disrupted normal mineral nutrient metabolism. Different molecular weight PE-particles may therefore have adverse effects on the soil-plant system.