| Abstract: | There is growing evidence that the phloem transport pathwayis leaky with passive unloading into the apoplast and activereloading from the apoplast. In this paper we report in vivomeasurements of unloading and reloading in immature stems ofbean expressed as a percentage per unit length of the photo-assimilateflow within the transport pathway. Gross unloading was up to6% cm-1 and net unloading up to 4% cm-1. Time constants of bulkflow through 10 cm of stem were about 4-6 min whereas thoseof net unloading were 8-13 min and of gross unloading, at themost, 7-8 min. Key words: Phloem transport, apoplast, bean stem |
