[Effects of Three Different Types of Microplastics on Cucumber Growth and Nitrogen Utilization]

Microplastics （MPs） are increasingly recognized for their detrimental effects on the environment. However， their influence on agricultural ecosystems， particularly on crops like cucumber （Cucumis sativus L.）， remains unclear. In this study， we conducted a greenhouse pot trial to examine how three types of microplastics - polyethylene （PE）， polyvinyl chloride （PVC）， and polyethylene terephthalate （PET）-affect the growth and nitrogen uptake of cucumber seedlings. The results showed that， on the whole， microplastic addition increased cucumber seedling biomass by ca. 9.5%. Specifically， the PE treatment significantly boosted leaf and root biomass by day 28， while PVC treatment notably enhanced leaf and stem biomass and total biomass by day 70. The PET treatment significantly increased leaf biomass at days 28 and 70. Furthermore， microplastic addition increased nitrogen uptake by 10.8%， and the PET treatment significantly enhanced nitrogen uptake at days 28 and 70. Additionally， all microplastic treatments significantly improved ¹⁵N utilization in cucumber roots by day 28， while PET notably enhanced leaf ¹⁵N utilization by days 56 and 70. In conclusion， microplastic addition promoted cucumber growth and nitrogen uptake， with variations depending on microplastic type. These results contribute to understanding microplastic effects on crop growth and nitrogen uptake， offering insights for evaluating their impact on agricultural ecosystems.