Spatial distributions and net deposition rates of Fe, Mn and Zn in the elongating leaves of wheat under saline soil conditions

In this study, we quantified the spatial distributions of Fe, Mn and Zn and their net deposition rates in the elongating and mature zones of leaf 4 on the main stem of spring wheat (Triticum aestivum L.) on a millimetre scale during its linear growth phase under saline soil conditions. Plants were grown in an illitic-chloritic silty loam with 0 and 120 mM NaCl in growth chambers. The sampling was conducted on the 3rd day after leaf 4 emerged during the photoperiod. The patterns of spatial distributions of Fe, Mn and Zn concentrations (mmol kg^-1 FW) in the growing leaves were distinct. Salinity affected the distribution pattern of Fe concentration on the FW basis, whereas it did not affect those of the Zn and Mn. The distribution patterns of Fe and Mn differed from those for N, P, K, Ca and Mg found in a previous study, whereas the distribution pattern of Zn was similar to those of Mg, P and N. The spatial distribution of the net deposition rates (mmol kg^-1 FW h^-1) in both treatments demonstrated the strongest sink for the micronutrients in the elongation zone, and their net deposition rates were enhanced by 120 mM NaCl at the middle of the elongation zone. From the results, we conclude that the inhibition of leaf growth of wheat is probably not due to the effect of salinity on Fe, Mn and Zn in leaves.