Zinc Deficiency in Wheat in Turkey

Abstract

Zinc (Zn) deficiency in soils and crop plants occurs nearly in all countries, particularly in cereal-growing areas. Turkey is among the countries with the most severe Zn-deficient soils. Previously, wheat grown in Central Anatolia was low yielding over many years, but the reason was unclear. In 1991/1992 a field experiment was conducted to determine whether micronutrients were a possible cause of the problem. Only with Zn application there was an impressive increase in growth and yield of wheat (T. aestivum L.). Based on these initial observations, a multi-institutional, long-term project on Zn deficiency in crop production in Central Anatolia was prepared and supported by the NATO “Science for Stability” Program. There were spectacular increases in grain yield of wheat with Zn fertilisation. In certain areas with very low yields (0.25 t ha), Zn application enhanced grain yield by a factor of 6–8. The total amount of soil Zn was fairly high, between 40 and 80 mg kg, but the level of plant available Zn was extremely low (DTPAZn: around 0.1 mg kg soil). Field experiments at different locations revealed that in soils containing less than 0.4 mg kg DTPA-extractable Zn, wheat, particularly durum wheat, responded significantly to Zn applications. Compared to irrigated conditions, wheat was more sensitive to Zn deficiency under rainfed conditions. Plants emerging from seeds with very high Zn concentrations (up to 55 mg kg dry weight) had increased seedling vigour and pathogen resistance, as well as yield. In addition, enhancing Zn concentration in seeds reduced seeding rate, with consequent economic benefits. The impressive effects of Zn fertilisers on crop yield evoked considerable interest by fertiliser companies, which in 1995 started producing Zn-containing compound fertilisers. Today, 12 years after the Zn deficiency problem was diagnosed as a critical problem for wheat production in Turkey, the total amount of Zn-containing compound fertilisers applied in Turkey is at a record level of 300,000 t. Ministry of Agriculture estimates put annual economic benefits from Zn fertilisation at US$100 million. As Zn deficiency is an important micronutrient deficiency in humans in Turkey, increases in grain Zn concentration by Zn fertilisation have obvious implications for human health. B.J. Alloway (ed.), Micronutrient Deficiencies in Global Crop Production. 181 © Springer Science + Business Media B.V. 2008