Retranslocation Of Boron In Broccoli And Lupin Plants During Reproductive Growth

Abstract

This study tested the hypothesis that xylem-borne boron (B) is retranslocated in phloem to reproductive sinks of plants Intact plants or detached transpiring shoots were supplied simultaneously with enriched l0B, strontium ( a xylem marker) and rubidium ( a xylem/phloem marker); the distribution of these compounds was determined as a function of time (i.e. up to 12 hours and 4 days for broccoli and lupin plants, respectively). The percent recovery of both l0B and rubidium in broccoli florets and lupin fruits was similar and markedly greater than that for strontium. Furthermore, the xylem-to-phloem transfer was rapid (within 2 h for broccoli and 1 day for lupin, the earliest harvest times), with the extent depending on B status of the plant.