Plastic mulch debris in rhizosphere: Interactions with soil-microbe-plant systems

Large amounts of plastic mulch debris (PMD) accumulated in the soil can endanger agroecosystems. However, little is known about the interactions between PMD and soil-microbe-plant systems. In this study, a pot experiment (four replicates) in tropical greenhouse was conducted to investigate the effects of PMD (polyethylene) at different concentrations (0, 0.4,0.8,4.0,6.0 g kg(-1)) on soil nutrients, rhizosphere bacterial communities and rice growth. This study further explored the interactive mechanisms between PMD and environmental factors based on correlation analysis and previous studies. The results showed that PMD continuously reduced the soil capabilities to store nutrients (C, N, P, humic-like substances) and increased the proportion of P and biodegradable dissolved organic matter (DOM). At the full ripening stage of rice growth, total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) in all PMD treatments significantly decreased by 60.86, 52.51 and 34.83% respectively as compared to CK (p < 0.05). Furthermore, PMD increased the total abundance of bacteria but reduced the diversity and evenness of bacterial communities, which further affected microbial metabolic functions. Total OTUs and Shannon decreased 0.02-17.05% and 0.69-7.55% in treatments. At harvest-time, PMD reduced the bio-mass and yield of rice with 1134 and 1924% (all treatments on average) lower than CK. Under the influence of PMD, the order of correlation size between PMD and one environmental factor was PMD-soil > PMD-microbe > PMD-plant, and the order of correlation between two environmental factors was soil-microbe > microbe-plant > soil-plant. Over all, PMD had the most significant negative effects on soil nutrients storage, followed by the change of microbial community structure and microbial metabolic functions. The negative effects of PMD on crops were relatively weak. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the effects of PMD on soil nutrients, rhizosphere bacterial communities, and rice growth through a pot experiment. The results showed that PMD significantly reduced soil nutrient storage capacity, impacted microbial community structure, and metabolic functions. Additionally, PMD also reduced rice yield and biomass.