Introductory Biology
Higher turgor pressure measured at sugar sources than at sugar sinks, creating a pressure gradient along the phloem.
Sugar loading into phloem at source tissues is accompanied by water entry, while sugar unloading at sink tissues is accompanied by water exit.
Disrupting phloem loading reduces the movement of sugars from source leaves to sink tissues.
Phloem sap moves from regions of higher hydrostatic pressure toward regions of lower hydrostatic pressure.