Evaluating the Role of Tobacco Stalk Biochar in Wheat Growth Under Microplastic Exposure

Abstract

The accumulation of microplastics in agricultural soils poses a serious threat to both crop production and ecosystem health. To explore potential remediation strategies, we conducted a two-factor pot experiment (PE-MPs × TSB). This study was designed to systematically analyze the interactive effects of polyethylene microplastics (PE-MPs) and tobacco stalk-derived biochar (TSB) on soil properties, physiological characteristics, and growth indicators of wheat. Results indicated that TSB addition significantly increased soil pH, organic matter, and available potassium content, which was associated with a mitigation of the soil acidification and nutrient imbalance observed under PE-MPs. Physiologically, TSB was linked to higher activities of antioxidant enzymes (SOD and POD) and maintained leaf chlorophyll content and photosynthetic function, thereby consistent with a reduction in oxidative stress and better maintenance of growth in the presence of PE-MPs. Furthermore, partial least squares structural equation modeling (PLS-SEM) supported a hypothetical cascading pathway for TSB’s dominant influence: soil improvement → physiological mitigation → growth recovery. The total effect of TSB on biomass (0.71) was substantially greater than that of PE-MPs (0.01). This study proposes a conceptual model and provides correlative evidence that is consistent with multi-level processes through which TSB may alleviate PE-MPs stress, thereby providing theoretical support for the resource utilization of agricultural waste and the green remediation of microplastic-contaminated soil.