Impact of Microplastics on the Growth and Physiological Response in Zea mays and Sorghum bicolor

The accumulation of microplastics (MPs) in agricultural soils poses a growing risk to terrestrial ecosystems, yet polymer-specific phytotoxic mechanisms remain only partially resolved. This study assessed the effects of 2% and 5% concentrations of low-density polyethylene (LDPE), polyvinyl chloride (PVC), and polypropylene (PP) MPs on Zea mays and Sorghum bicolor. Microplastic exposure induced reductions in plant growth parameters and photosynthetic pigments, accompanied by enhanced oxidative stress, depending on the concentrations. Soil enzymatic activities including dehydrogenase, acid and alkaline phosphatase were also significantly modulated, indicating alterations in biochemical processes and nutrient cycling in soil. Among the three types of MPs studied, the marked phytotoxic responses were witnessed in PVC, followed by LDPE, whereas PP exhibited comparatively lower toxicity. Consistently the highest MP concentrations (5%) led to more pronounced detrimental effects on both the plants. These findings shed light on polymer-specific and concentration-dependent impacts of MP on plants and emphasize the critical need for deeper understanding and more comprehensive regulatory mechanisms that could be beneficial in improving plant tolerance and various remedial measures to reduce the effects of the MPs on the agroecosystems.