N enhanced-activities of transporter proteins contributing to xylem loading or nitrogenous compounds facilitating Zn transport in plants such as nicotianamine (NA) and deoxymugineic acid (DMA). Shi et al. (2012) provided the evidence that N supply significantly improved NA rather than DMA in old leaves of barley, irrespective of iron supply. Furthermore, Barunawati et al. (2013) showed that increasing N supply significantly enhanced NA concentrations in flag leaves and NA exudation rates from senescing flag leaves. The latter suggested more NA can be loaded into the phloem for long-distance transport. Aciksoz et al. (2011)