Microplastics in Agroecosystems: Pathways, Plant Uptake Mechanisms, and Advanced Scanning Techniques for Detection in Plant Tissues

The sustainability, crop production, and food safety of agriculture are increasingly challenged by microplastic pollution, as agricultural soils are the largest reservoirs and may serve as points of contact for plastic particles in the food chain. This review provides a comprehensive overview of plant materials, fate and uptake pathways, detection techniques, and the possible risks of microplastics in agriculture. Agroecosystems are also a source of microplastics, such as plastic mulch films, sewage sludge, compost and manure additives, wastewater irrigation, polymer-coated fertilizers, greenhouse materials, atmospheric deposition, and decomposition of discarded agricultural plastics. Their distribution and mobility in soil are controlled by polymer composition, particle size, morphology, density, surface ageing, soil texture, organic matter content, tillage practices, runoff, leaching, and soil biota. Recent data show that microplastics, especially smaller microplastics and nanoplastics, can attach to root surfaces, penetrate plants via cracks in roots, areas of lateral root development, and apoplastic pathways, and eventually move to tissues aboveground. Plant tissue detection is often accomplished by digestion of the sample, density separation, visual and fluorescence microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, pyrolysis–gas chromatography mass spectrometry, and electron microscopy, but standardization of these methods remains a significant challenge. Microplastics can disrupt seed germination, root structure, nutrient absorption, photosynthesis, oxidative homeostasis, biomass buildup, yield development, and quality. Further, their capacity to transport additives, plasticizers, heavy metals, and persistent organic pollutants raises concerns about the transfer of contaminants to edible plant parts and their potential transfer to human diets. Further studies are needed focusing on field-realistic exposure conditions, long-term crop–soil interactions, nanoplastics behaviour, standardised analysis procedures, uptake and translocation pathways, edible crop risk assessments, and sustainable mitigation approaches to reduce microplastics in agroecosystems.