Grain yield,zinc efficiency and zinc concentration of wheat cultivars grown in a zinc-deficient calcareous soil in field and greenhouse

Field experiments were carried out to study grain yield, zinc (Zn) efficiency and concentrations of Zn in shoot and grain of 37 bread wheat (Triticum aestivum) and three durum wheat (Triticum durum) cultivars grown in a Zn-deficient calcareous soil with (23 kg Zn ha⁻¹), and without, Zn fertilization in 1993–1994 and 1994–1995. The same Zn-deficient soil was used in greenhouse experiments to study shoot dry weight, Zn efficiency and shoot Zn concentrations of 21 bread and three durum wheat cultivars (same cultivars used in the field experiments). Zinc fertilization of cultivars in the field enhanced grain yield on average by 30% in both years. Increases in grain yield to Zn fertilization varied substantially between cultivars from 8% to 76%. Accordingly, there was large variability in Zn efficiency of cultivars, expressed as the ratio of grain yield or shoot dry-matter yield produced under Zn deficiency compared to that under Zn fertilization. On average, Zn efficiency values ranged from 57% to 92% for grain yield in field experiments and from 47% to 83% for shoot dry weight in greenhouse experiments. Most of the cultivars behaved similarly in their response to Zn deficiency in the field and greenhouse. The cultivars selected from local landraces had both, a high Zn efficiency and high yield under Zn-deficient conditions. The bread wheat cultivars, improved for irrigated conditions, had generally low Zn efficiency and low yield, both in the field and greenhouse. All durum wheat cultivars in this study also showed low levels of Zn efficiency, grain yield and shoot dry weight under Zn deficiency. Overall, there was no relation between Zn efficiency values and Zn concentrations in grain or shoot dry matter. The results presented here demonstrate the existence of substantial variation in Zn efficiency among wheat cultivars, particularly bread wheat cultivars, and suggest that wheat landrace populations are a valuable source of genes to improve high Zn efficiency of wheat for Zn-deficient soils.