Abstract
The hydraulic acclimation of napiergrass (Pennisetum purpureum Schumach.) shoots to shading depends on that of stem. In this study, we measured the hydraulic and morphological properties of a stem segment (a node+an internode), node and internode of napiergrass and compared these properties among treatments to investigate the effect of shading on the hydraulic acclimation of stems. Plants were grown under shade conditions (30% of full sunlight) for 30 d (S plants), shade conditions for 24 d followed by full-sunlight conditions for 6 d (SF plants), or full sunlight for 30 d (control, C plants). The response of total hydraulic resistance (R) of stem segment was similar to that of internode, S plants showed the highest R and SF plants had an intermediate value between the other plants. Shading made internode long and narrow, resulting in the increase in R. In addition, normalizing internodal R by length and cross-sectional area (R sp) was co-related with cross-sectional area. While, there was no significant difference in R of node among the treatments, R sp was co-related with vascular bundle density. The response of R to light treatment in napiergrass stems depended on that of internode through the morphological changes.
