ABSTRACT
Essentiality of copper (Cu) for higher plants was discovered in 1931 by C. B. Lipman and G. MacKinney (Marschner, 1995; Fageria et al., 1997a). Since then, knowledge of its role in improving crop production has improved. Copper deficiency has been reported in cereals, vegetables, grasses, and forage legumes in various parts of the world (Clark, 1982; Baligar et al., 2001; Brady and Weil, 2002; Fageria et al., 2006). The main causes of micronutrients deficiency including copper are (1) intensive cultivation; (2) higher copper requirements of modern cultivars due to higher yields; (3) loss of topsoil layers by soil erosion which contain higher organic matter and copper; (4) use of liming in acid soils, which reduces copper concentration due to increases in soil pH and adsorption of this element; (5) low rates used by farmers, especially in developing countries; (6) increased use of high-analysis fertilizers with low amounts of micronutrients; (7) low rate of application or no use of organic manures; (8) involvement of natural and anthropogenic factors that limit adequate plant availability and create element imbalances; (9) sandy soils low in organic matter content, which may become deficient in Cu because of leaching losses; and (10) no recycling of crop residues (Fageria et al., 2002). High rates of N fertilizer have greatly accentuated Cu deficiency in Europe, Australia, and India (Gartrell, 1981). The application of inorganic N and P or livestock manure to increase the fertility of certain soil types has caused major yield and quality losses in Canadian cereal crops (Evans et al., 2007). Copper deficiency can also be induced by certain foliar-and soil-applied herbicides (Evans et al., 1990).
