Plant electrophysiological characteristics reveal the leaf intracellular nutrient metabolism and stress tolerance underlying Se(IV)-mediated alleviation of polyethylene stress in Plantago asiatica

Leaf intracellular nutrient metabolism plays a critical role in determining plant stress tolerance.Selenium(IV) supplied as sodium selenite (Na2SeO3; SeO3 2-) has been reported to enhance plant resistance to polyethylene (PE, microplastics), yet its effects on intracellular nutrient metabolism under PE stress remain unclear.Plantain (Plantago asiatica L.) was exposed to PE (1500 mg kg -1 ) and supplemented with Se(IV) at 0, 1.25, 2.5, 12.5, and 25 mg kg -1 (as Na2SeO3).Growth traits, photosynthetic performance, and leaf electrophysiological characteristics were measured, and the membership function method was used to comprehensively evaluate intracellular water-holding capacity (IWHC), nutrient transport capacity (NTC), and metabolic activity (MA).The Se(IV) dose 2.5 mg kg -1 produced the strongest overall mitigation of PE stress, increasing IWHC and MA by 173.95% and 24.70%, respectively, while maintaining a high NTC (129.69%above the PE-only treatment).When Se(IV) exceeded 2.5 mg kg -1 , mitigation weakened: At 12.5 and 25 mg kg -1 , IWHC, NTC, and MA increased by 77.01%, 105.01%, and 2.24%, and by 89.06%, 105.31%, and 16.22%, respectively, compared with the PE-only treatment, indicating that excess Se(IV) did not further improve plant performance.Overall, plant electrophysiological techniques provide a rapid and non-destructive approach to evaluate Se-mediated alleviation of microplastic stress and support the rational use of Se in agriculture.