ABSTRACT
Iron (Fe) is an essential micronutrient for the growth and development of crop plants. Iron deficiency is a complex disorder, and it occurs in response to multiple soil, environmental, and genetic factors (Wiersma 2005). Factors that can contribute to Fe deficiency in plants include low Fe supply from soil; high lime and P application; high levels of heavy metals such as Zn, Cu, and Mn; low and high temperatures; high levels of nitrate nitrogen; poor aeration; unbalanced cation ratios; and root infection by nematodes (Fageria, Baligar, and Wright 1990; Fageria 2009). Iron deficiency has been observed in Brazilian upland rice when it is grown in rotation with dry beans and soybeans on Oxisols and Ultisols (Fageria, Baligar, and Jones 2011). Oxisols and Ultisols are highly weathered soils that have low fertility and that are acidic in reaction (Fageria and Baligar 2008). Liming is an essential and predominant practice for correcting acidity of these soils. Therefore, iron deficiency observed in upland rice grown on these soils is due to increases in soil pH, rather than low levels of iron.
