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 human s in Turkey. About 14 Mha of cropped land in Turkey are known to be Zn defi cient, particularly cereal growing areas of Anatolia, In 1993, a joint rese arch project was started in Turkey with the financial support of the NATO-S cience 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 acid growth chamber experiments were carried to study mor phological, physiological and genetic factors determining the bases of geno typical differences in Zn efficiency among cereal species and within cultiv ars of wheat. Among the cereals, rye had particularly high Zn efficiency (h igh yield under Zn deficiency), There were large genotypical differences am ong wheat lines. High Zn efficiency was closely associated with enhanced ca pacity of some lines to take up Zn from soils, but not with increased Zn ac cumulation per unit dry weight of shoot or grain. Measurement of Zn-contain ing superoxide dismutase activity in leaves revealed that an efficient util ization 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 bioavailabilit y, were extremely high and ranged between 95 and 216 for crops grown severe ly on Zn-deficient soils of Central Anatolia. In the studies concerning det ermination of Zn nutritional status of school children in Southeastern Anat olia, most children were found to be of shorter stature and had very low le vels of Zn (<100 mg kg(-1)) in hair. (C) 1999 Published by Elsevier Science B.V. All rights reserved.