Zinc deficiency as a practical problem in plant and human nutrition in Turkey: A NATO-science for stability project

Zinc (Zn) deficiency is a critical nutritional problem for plants and humans in Turkey. About 14 Mha of cropped land in Turkey are known to be Zn deficient, particularly cereal growing areas of Anatolia. In 1993, a joint research project was started in Turkey with the financial support of the NATO-Science for Stability Programme to select and characterize cereal genotypes with high yield and/or high Zn accumulation in grain under deficient supply of Zn.Field, greenhouse and growth chamber experiments were carried to study morphological, physiological and genetic factors determining the bases of genotypical differences in Zn efficiency among cereal species and within cultivars of wheat. Among the cereals, rye had particularly high Zn efficiency (high yield under Zn deficiency). There were large genotypical differences among wheat lines. High Zn efficiency was closely associated with enhanced capacity of some lines to take up Zn from soils, but not with increased Zn accumulation per unit dry weight of shoot or grain. Measurement of Zn-containing superoxide dismutase activity in leaves revealed that an efficient utilization of Zn at the tissue or cellular level is an additional major factor involved in Zn efficiency of cereals.Zinc present in grains from Anatolia seems to be not bioavailable. Phytate : Zn molar ratios in grains, a widely accepted predictor of Zn bioavailability, were extremely high and ranged between 95 and 216 for crops grown severely on Zn-deficient soils of Central Anatolia. In the studies concerning determination of Zn nutritional status of school children in Southeastern Anatolia, most children were found to be of shorter stature and had very low levels of Zn (<100 mg kg⁻¹) in hair.