PubMed · 2026-06-30
Adding selenium to contaminated rice paddies cuts the amount of cadmium, arsenic, lead, and other toxic metals that rice grains absorb, by up to 54%. The mechanism turns out to be a chain reaction inside the root: selenium boosts a plant hormone that expands air channels in the root, which pumps oxygen into the soil, which triggers a rust-like iron coating on the root surface that traps the toxic metals before they can enter the plant.
Soil selenium amendment (1 mg/kg) reduced grain cadmium by 54%, arsenic by 34%, lead by 41%, chromium by 21%, nickel by 42%, and cobalt by 39% compared to untreated controls.
Selenium increased auxin (a plant growth hormone) levels by 2.74-fold, expanding root air-channel (aerenchyma) area from 34% to 65% of cortical cross-section.
Root surface iron plaque increased 5.64-fold under selenium treatment, with labile iron and manganese fluxes in the rhizosphere dropping by 54-89%, confirming that an oxidative iron barrier was responsible for blocking toxic metal uptake.
