Effects of different nitrogen forms and phloem-scalding on iron transport in phloem of maize plants

The effects of different nitrogen forms on iron transport in phloem and reutilization in maize plants were studied by phloemblocking technique with solution culture under controlled conditions. The results showed that the scalding of phloem led to a decrease in biomass of root and new leaves and increase in biomass of primary leaves and stem, an increase in reutilization of Fe in roots and a decrease of Fe in primary leaves, especially for plants without Fe supply, an increase of weight of xylem sap and a decrease of its Fe concentration, and also for deficient Fe plants. The remobilization of Fe in root was enhanced by scalding for maize plants with NO3--N or NH4+-N. Irrespective of NO3--N, NH4+-N supply favors the transport of Fe in xylem and phloem of maize plants whether the phloem is scalded or not. 