Exploring the complexities of rice iron toxicity: Paradoxes, mechanisms, and strategic deliberations.

Iron (Fe) toxicity in rice presents a paradox: excessive soil Fe in tropical flooded soils reduces yields by 15-30 %, yet edible grains remain Fe-deficient, worsening global "hidden hunger", which affects 1.72 billion people. This paradox arises from inefficient Fe translocation from roots to grains and complex research landscapes: field, pot, and hydroponic studies yield conflicting tolerance rankings, hindering mechanistic insights. Potassium (K) mitigates Fe toxicity in some cultivars but shows inconsistent effects across fertilizer forms and growth stages. Biofortification efforts face trade-offs between enhancing grain Fe and avoiding toxicity. Key challenges include the lack of a unified research framework, incomplete identification of Fe-transporter genes, and limited microbial fertilizer applications. This review synthesizes mechanisms, evaluates methods, dissects K-Fe interactions, and proposes breeding strategies.