Seedling Zinc-Uptake in Wheat Cultivars of Varying Zinc-Use Efficiency.

Field screening of wheat (Triticum aestivumL.) lines for zinc (Zn)-use efficiency (ZUE) is a time consuming exercise. In the present experiment, we examined some important and early crop stage phenotypic and physiological trait(s), which could be used for a rapid screening of a large number of wheat lines for ZUE. Four wheat cultivars of varying ZUE (‘UP2628ʹ, ‘UP262ʹ, ‘PBW175ʹ, and ‘UP2554ʹ) were screened for dry matter accumulation, root characteristics, tissue partitioning of Zn, and kinetic parameters of Zn uptake under Zn-deficient (–Zn) and Zn-sufficient (+Zn) conditions in a sand culture. Under –Zn condition, ‘UP262ʹ (Zn-use inefficient) had maintained relatively higher pH (>6.6) around roots in contrast to ‘UP2628ʹ (Zn-use efficient) that maintained relatively lower pH (<6.2) and also produced relatively finer roots with higher number of forks and crossings and had higher cation exchange capacity as compared to other cultivars. Under –Zn, ‘UP262ʹ accumulated more dry matter and Zn in roots with poor translocation to shoots than under +Zn. Time-dependent uptake of Zn in the roots and shoots of all wheat cultivars conformed to the first-order kinetic equation and the computed intercepts and slopes were also related to their Zn uptake and translocation behavior. In contrast to ‘UP262ʹ cultivar, ‘UP2628ʹ showed higher translocation of Zn to the shoots under –Zn condition. In short-term sand cultures, Zn translocation index (Zn uptake in shoot/Zn uptake in roots) could be used as an important criterion for selection of Zn-use efficient wheat lines. [ABSTRACT FROM AUTHOR]