Zinc in Soil Environment for Plant Health and Management Strategy

Abstract

Zinc is an essential element for photosynthesis and its deficiency may play a role in the reduction of activity of rubisco and hence decreased rate of photosynthesis in higher plants. Zinc deficiency sometimes resembles Fe/Mn deficiencies. Under severe zinc deficiency the shoot apices die ('die-back') as is widely distributed. Zinc toxicity leads to chlorosis in young leaves. Induced manganese deficiency might also be of importance as high zinc supply strongly decreases the manganese content of plants. Most preventing measures for zinc deficiency are selection of Zn efficient variety that is tolerant to high level of bicarbonate as well as low zinc in soil. Curative measure for correcting are application of 20-25 kg/ha ZnSo4 in acid soil, 22 kg Zn/ha initially followed by 5-10 kg Zn in the later years or 50% gypsum + 10 t GM + 22 kg Zn once in 2-3 years in sodic soils, 1.0-1.5 kg/ha Zn as foliar spray at tillering stage and 2 times latter is very helpful for correct this deficiency. Zinc is very tightly bound to phytic acid and the formation of protein-zinc-phytic acid complexes increases the resistance to hydrolysis that leads to decrease in bioavailability of Zn to human and animals. Enrichment of cereal grains with Zn through both genetic (e.g., breeding) and agronomic (e.g., application of Zn fertilizers) biofortification is a high priority area of research, and will contribute to minimizing Zn-deficiency-related health problems in human populations.