Iron Toxicity

Content

Historical Information
  Determination of Essentiality
Functions in Plants
Forms and Sources of Iron in Soils
Diagnosis of Iron Status in Plants
  Iron Deficiency
  Iron Toxicity
Iron Concentration in Crops
  Plant Part and Growth Stage
  Iron Requirement of Some Crops
  Iron Levels in Plants
    - Iron Uptake
    - Movement of Iron within Plants
Factors Affecting Plant Uptake
  Soil Factors
  Plant Factors
Soil Testing for Iron
Fertilizers for Iron
References

Iron toxicity is not a common problem in the field, except in rice crops in Asia (29). It can also occur in pot experiments, and in cases of oversupply of iron salts to ornamental plants such as azaleas. The symptoms in rice, known as ‘Akagare I’ or ‘bronzing’ in Asia, include small reddish-brown spots on the leaves, which gradually extend to the older leaves. The whole leaf may turn brown, and the older leaves may die prematurely (29). In other species, leaves may become darker in color and roots may turn brown (29). In rice, iron toxicity seems to occur above 500 mg Fe kg-1 leaf dry weight (30) (Figure 11.5).



Symptoms of iron toxicity in lowland rice (Oryza sativa L.) in Sri Lanka as a consequence of decreased redox potential under submergence
FIGURE 11.5 Symptoms of iron toxicity in lowland rice (Oryza sativa L.) in Sri Lanka as a consequence of decreased redox potential under submergence.