Physiological and absorption characteristics of sweet potato in response to polyethylene microplastic

Microplastics (MPs) pollution poses some serious problems in sweet potato farms. In this study, pot experiment, liquid adsorption experiment and fluorescence observation experiment were conducted to explore the effects of normal and aging MPs on physicochemical properties in soil, growth and phosphorus (P), potassium (K) absorption in sweet potato; P and K adsorption in liquid environment; and the distribution of normal MPs in sweet potato tissues respectively. The results showed that 5 μm normal polyethylene (PE) MPs significantly reduced pH and increased EC of soil compared to aging PE MPs. In addition, normal PE MPs can also significantly improved the biomass growth rates of sweet potato by adsorping more Olsen-P and Olsen-K in soil, and increasing K concentration in stems compared with aging PE MPs. Although there was no significant difference between normal and aging PE MPs on the degree of membrane lipid peroxidation in sweet potato leaves, the normal PE MPs made sweet potato exhibit the stronger oxidative stress. Fluorescent PE MPs spheres just appeared in the cortical tissues of roots and stems. Our study finds that the sweet potato will not be harmed by a single PE MPs contamination in a short period of time.