Single and Joint Effects of Imidacloprid and Microplastics on Lettuce Growth

Understanding the joint effects of microplastics (MPs) and pesticides in agricultural environments is important, as their co-existence may lead to plant responses distinct from those caused by single-contaminant exposure. This study investigated the individual and joint effects of low-density polyethylene (LDPE) MPs (0–3%) and imidacloprid (0–219 mg kg⁻¹) on lettuce to address current knowledge gaps. Growth parameters, chlorophyll content, and imidacloprid uptake in lettuce were evaluated following a 28-d exposure period. Co-exposure to LDPE MPs and imidacloprid led to a 68% reduction in total fresh weight, compared to a 49% reduction with imidacloprid alone. Combined treatment also significantly decreased root and shoot length, number of leaves, and chlorophyll content, and induced morphological changes such as leaf browning and stunted root development. However, LDPE MPs did not affect imidacloprid uptake, suggesting limited influence of MPs on the bioavailability of imidacloprid under the conditions studied. The results emphasize the intensified harmful effects resulting from co-exposure to pesticides and MPs, highlighting the need for further study on management strategies for these contaminants in agricultural land to ensure the sustainability of agricultural systems.