Effects of microplastics and salt single or combined stresses on growth and physiological responses of maize seedlings

and MDA content, a disrupted chloroplast structure, and reduced chlorophyll content, ultimately leading to a decline in chlorophyll fluorescence parameters and photosynthetic efficiency. Single MPs or NaCl stress led to the accumulation of proline, soluble proteins, and soluble sugars, while the combined stresses further increased the content of these osmotic substances in plants. Moreover, single or combined stress increased the activity of CAT, POD, SOD and the content of AsA and GsH. Collectively, NaCl and MPs single or combined stress exert notable toxic effects on maize seedling growth. Although the combined stress inhibited seedling growth more than the single stress, the combined stress of MPs and NaCl showed antagonistic effects. These findings underscore the importance of assessing the ecological risks posed by the combined effects of MPs and salt stresses on maize plants.