Direct absorption of atmospheric lead by rapeseed siliques is the leading cause of seed lead pollution.

Rapeseed cultivation is a novel approach to safely utilizing lead (Pb) contaminated farmland. However, the mechanism of Pb absorption in seeds remains uncertain. A field experiment was conducted to explore this mechanism with two contrasting treatments: rapeseed exposed to atmospheric deposition and non-exposed treatment. Non-exposed treatment ultimately decreased Pb content in leaf, silique, and seed by 46.7%, 53.7%, and 53.6%, respectively. Sub-microstructure analysis further confirmed that rapeseed leaves and siliques could directly absorb atmospheric Pb. In addition, Pb isotope analysis indicates that atmospheric deposition is the primary source of silique and seed Pb. The root and silique organs had relative Pb contributions of 28.0% and 72.0%, respectively, to seed. Thus, the direct absorption of atmospheric Pb by siliques during the filling stage was found to be the leading cause of seed Pb pollution. [Display omitted] • Non-exposed treatment substantially decreased the seed Pb content by 53.6%. • Both of silique and leaf can directly absorb atmospheric Pb. • The Pb of siliques and seeds mainly comes from atmospheric deposition. • The siliques had a relative contribution of 72% to seed Pb. • Uptake of atmospheric Pb by siliques is the leading cause of seed Pb pollution. [ABSTRACT FROM AUTHOR]