Effects of transverse movement of water in xylem on patterns of water transport within current‐year shoots of kudzu vine, Pueraria lobata

Abstract

Summary This study investigated the effects on water transport patterns of the transverse water movement in xylem, on a whole‐shoot scale, using current‐year shoots of kudzu vine (Pueraria lobata (Willd.) Ohwi). The connections between xylem vessels were detected by dye injection and were found to be distributed throughout the internode. This means that short internodes limit the connections between vessels. The hydraulic conductance of the internode‐to‐petiole path decreased with successive cutting of the internodes. To estimate hydraulic patterns at the whole‐shoot scale, the hydraulic conductance of the shoot base‐to‐petiole path (KBP) were measured. These were compared with two mathematical models representing extreme examples of connections between vessels – the interconnected model and the independent model. The former model assumes a high capacity for the transverse movement of water in xylem tissues. The KBP values measured were explained more accurately by the interconnected model than by the independent model. These results suggest that kudzu vine has a large capacity for the transverse movement of water in xylem, which contributes to the effective transport of water from internodes to leaves that offsets sectored transport at the whole‐shoot scale.