Real-time analysis of nitrogen translocation in plants

Nitrogen absorbed by roots is transported to the leaves through xylem vessels and then retranslocated to the new leaves, such as root and storage organs through sieve tubes. It is very important to know how this nitrogen movement occurs in the plants and what mechanisms are involved in controlling this movement in order to increase the efficiency of fertilizer. In this experiments, 13N and 15N was used to detect the nitrogen circulation in plants, in combination with the technique for positron detection in real time and for collection of sap in sieve tubes and analysis of 15N in it. By using 13N, nitrogen movement from root to shoot was analyzed within 10 min after 13N was applied to the roots. On the other hand, nitrogen retranslocation through sieve tubes was detected by the analysis of 15N in the phloem sap over 6 hrs. All data suggest the dynamic translocation of nitrogen in rice plants. (author)