Does zinc uptake relate well with differential zinc efficiency of barley genotypes?

To some extent, differential zinc (Zn) efficiency of cereals, particularly differences between species may be attributed to phytosiderophores (PSs) release and inorganic Zn (Zn2+) uptake; however, the discrepancies within a given species are still under discussion. Moreover, studies on the explanations of differential Zn efficiencies of barleys are limited. That is why using two barley (Hordeum vulgare L.) cultivars (Zn-efficient, Tarm-92 and -inefficient, Hamidiye-79), two short-term uptake experiments were designed with two forms of Zn, free Zn (Zn2+) or PS chelated Zn (Zn-PS) labelled with radioactive Zn (65Zn) in nutrient solution culture. Similar to earlier studies, the Zn uptake by roots and its translocation to shoots of barley supplied as either free (Zn2+) or chelated (Zn-PS) was induced under Zn deficiency. Although according to results of previous works, a close relationship between Zn2+ uptake of roots and Zn efficiencies of the same barley cultivars might have existed, the outcomes of the present research showed the opposite. Neither the uptake of Zn2+ and Zn-PS from roots nor their translocation to shoot had any compatible connection with the Zn efficiencies of barley cultivars. So the reason for differential Zn efficiency within a given cereal species remained unclear including barley as well.   Key words: Barley, phytosiderophores, uptake, zinc, zinc efficiency.