Uptake, translocation, and interactions of zinc and manganese in crop plants

Zinc deficiency is the most widespread micronutrient disorder and it is becoming insreasingly important in crop production. In the tropics, it occurs in India, Pakistan, Philippines, and Colombia under lowland rice cultivation. But calcareous soils are particularly prone to ZN-deficiency and in these soils even upland crops are affected. Literature is full of such example. In India, more research efforts have gone into zinc fertilization than in all the remaining micronutriant deficiency disorders put together. For example, Katyal et al. (1980) reported that out of about 55 000 soil samples analyzed so far, nearly 50 percent fell into zinc deficient category, whereas the deficiency of remaining micronutrient cations was confined to less than 12% of the samples