Foliar nano-selenium regulates Cardamine violifolia physiology and rhizosphere microenvironment for synergistic lead-contaminated soil remediation

Phytoremediation of lead (Pb)-contaminated soil exhibits advantages in ecological compatibility and sustainability. This study, using Cardamine violifolia as the experimental material, explored the changes in plant physiological indices and soil properties under Pb stress following foliar application of nano-selenium (SeNPs). Results indicated that under Pb stress, SeNPs application increased plant biomass by 2.38-fold (Pb+Se20), total chlorophyll content by 15.61% (Pb+Se10), and root Pb content by 2.72-fold (Pb+Se20); it decreased MDA content by 23.41% (Pb+Se5), increased underground flavonoid content by 34.57% (Pb+Se10), reduced the Pb translocation coefficient by 30.75% (Pb+Se10), and enhanced S-FDA activity by 26.86% (Pb+Se20). Foliar application of SeNPs affects the uptake and translocation of Pb in plants and enhances their capacity to accumulate Se and Pb. SeNPs improve rhizosphere soil nutrition by regulating plant rhizosphere secreted metabolites (such as carbohydrates, organic acids, and polyphenols). Meanwhile, Pb-tolerant microbial populations, such as Aquicella , Blastocatellaceae , Hirschia , and Ilumatobacter , are recruited around the rhizosphere, ultimately resulting in increased plant biomass and Pb accumulation. Foliar application of SeNPs re-integrated the soil-plant balance by improving plant physiological status and soil properties. • Nano-selenium promotes an increase in plant Pb content. • Se enhances plant biomass under lead stress. • Se improves the abundance of beneficial rhizosphere microorganisms. • Se application increases S-FDA activity in rhizosphere soil. • Se enhances the organic matter content in rhizosphere soil.