The Potential of Flax ( <i>Linum usitatissimum</i> L.) in Phytoremediation of Heavy Metal-Contaminated Farmland: A Review

Heavy metal contamination in farmland has become a major environmental issue threatening sustainable development of global agriculture and human health. Flax (Linum usitatissimum L.) shows great potential in the phytoremediation of farmland contaminated by heavy metals. This paper systematically summarizes that flax has strong tolerance and enrichment capacity for various heavy metals, and elaborates on the molecular and physiological mechanisms underlying heavy metal tolerance of flax, specifically including: cell wall cross-linking, protoplast detoxification, vacuolar compartmentalization, the response of enzyme systems to oxidative stress, and the activation of the phenylpropane pathway. It also summarizes the technical approaches to improve the remediation efficiency of flax through regulators, microorganisms, and water-fertilizer management. Meanwhile, it analyzes the remediation effect of flax on farmland with different pollution levels. This paper focuses on exploring the utilization directions of flax biomass resources harvested from contaminated farmland, covering fields such as composite materials, biochar, building materials, and sewage treatment materials, thereby providing solutions to avoid secondary pollution caused by biomass. Flax can realize the “synchronous remediation and utilization” of heavy metal-contaminated farmland and is a remediation crop with broad application prospects. In the future, its remediation efficiency will be further improved through variety breeding and new technologies development.