Phloem boron mobility in diverse plant species

Recent evidence suggests that the production and translocation of polyols will influence the phloem mobility of B in higher plants. The patterns of B distribution in plants, the procedures used to determine plant B status and the approaches used to manage B fertilization are all fundamentally affected by phloem B mobility. Detailed information on the occurrence of polyols in various species is unavailable and hence the extent of B mobility cannot be adequately predicted. Here, the phloem mobility of B has been tested in a number of plants producing polyols. Two approaches have been used, the B concentration gradient along a shoot and foliar B-10 labelling. Results indicate that B exhibits significant phloem mobility in the species that produce polyols, but the extent of B retranslocation varies between species even within genera.