Iron toxicity in wetland rice and the role of other nutrients

Iron (Fe) toxicity is a widespread nutrient disorder of wetland rice grown on acid sulfate soils, Ultisols, and sandy soils with a low cation exchange capacity, moderate to high acidity, and active Fe (easily reducible Fe) and low to moderately high in organic matter. Iron toxicity reduces rice yields by 12-100%, depending on the Fe tolerance of the genotype, intensity of Fe toxicity stress, and soil fertility status. Iron toxicity can be reduced by using Fe-tolerant rice genotypes and through soil, water, and nutrient management practices. This article critically assesses the recent literature on Fe toxicity, with emphasis on the role of other plant nutrients, in the occurrence of and tolerance to Fe toxicity in lowland rice and puts this information in perspective for future research needs. The article emphasizes the need for research to provide knowledge that would be used for increasing rice production on Fe-toxic wetlands on a sustainable basis by integration of genetic tolerance to Fe toxicity with soil, water, and nutrient management.