A survey of root pressure in 53 Asian species of bamboo

Introduction Root pressure is a potentially important mechanism for dissolving embolisms in previously cavitated vessels, but the occurrence of root pressure is not a universal property in plants. Material and methods We suggest that root pressure might be more common in monocots than dicots because in dicots, cambial growth can replace embolized vessels but monocots have no secondary growth and hence need mechanisms for repair of embolized vessels. In this paper, bubble manometers were used to investigate 53 bamboo species from 10 genera. Results A survey of root pressure in 53 Asian species of bamboo revealed that all possessed root pressure and in some species root pressure was high enough to cause guttation of liquid from leaves at predawn. In contrast, in woody vines were we might expect root pressure to be common because of reduced cambial growth, root pressure is comparatively rare. Xylem exudate and guttation fluid had an osmotic pressure greater than root pressure and this can be explained in terms of a low reflection coefficient in context of how root pressure is generated according to the composite membrane model of roots. Conclusion We conclude that the next logical step is to survey bamboo species to determine how common cavitation evens are and to determine if refilling of vessels occurs by root pressure.