ABSTRACT
Zinc (Zn) is classified as a heavy metal among those micronutrients that are essential for plant growth and development. Zinc deficiency is more common than deficiency of other micronutrients, and it occurs mainly on highly weathered tropical soils, on soils low in organic matter content, and on sandy soils. Zinc deficiency is widespread in the world’s rice-growing regions. Graham (2008) reported that half of the world’s soils are intrinsically deficient in Zn. Similarly, Alloway (2008) also noted that Zn deficiency in crop production is found worldwide. Zinc deficiency in rice has been reported in South America (Fageria and Stone 2008; Fageria, Baligar, and Jones 2011), Asia (De Datta 1981; Singh 2008), Australia (Graham 2008), China (Zou et al. 2008), Turkey (Cakmak 2008), Europe (Sinclair and Edwards 2008), the United States (Brown 2008), and Africa (Waals and Laker 2008).
