[Effect of Polyethylene Microplastics on Physiological Property and Vanadium Accumulation of Maize （Zea mays L.） Seedlings Under Vanadium Stress]

This study sought to elucidate the impact of polyethylene microplastics （PE） applied externally on the physiological traits, antioxidant activity, and vanadium （V） accumulation in maize （Zea mays L.） seedlings subjected to V stress. The maize variety used for this work was MY73, and V-stress was induced by cultivating seedlings in a soil culture setup with 150 mg·kg^-1 of V incorporated into each pot. The findings revealed that V-stress at 150 mg·kg^-1 considerably reduced chlorophyll levels, photosynthetic rates, and the biomass accumulation in maize seedlings. Furthermore, V-stress led to a decline in soluble protein content, an increase in MDA levels, and heightened cell membrane lipid peroxidation, along with augmented activities of antioxidant enzymes, including superoxide dismutase （SOD） and peroxidase （POD）. Exogenous polyethylene microplastics could promote the accumulation of soil organic matter and reduce the content of available V in the soil but had no obvious effect on soil pH value. It also decreased the V content in the aboveground and underground parts of maize by 3.89%-61.78% and 7.11%-18.04% and reduced V accumulation in maize seedling roots by 25.90%-46.29%. While exogenous PE reduced the MDA content in roots and aboveground parts of maize by 6.76%-35.11% and 5.85%-24.30%, it increased the soluble protein contents in roots and shoots by 8.21%-18.19% and 8.74%-19.20%, respectively. Compared with V stress alone, POD content in maize roots and shoots increased by 79.31% and 41.01%, respectively, and SOD content in maize shoots increased by 6.18% under the 0.1% PE treatment. Overall, exogenous PE could give rise to enhanced photosynthesis and augmented activities of antioxidant enzymes and decreased the content and accumulation of V in maize （Z. mays L.） seedlings, which may alleviate cell membrane lipid peroxidation. Additionally, the mitigation effect was best under the 0.1% PE treatment. All of these results can lay a certain data foundation for the study of the interaction effect between microplastics and heavy metals in the soil-plant system.