© 1993 Heron Publishing—Victoria, Canada
Diurnal pattern of leaf extension in Salix viminalis relates to the difference in leaf turgor before and after stress relaxation
A. J. S. McDonald (1, 2) and I. Stadenberg (1)
1. Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences, Box 7072, S-750 07 Uppsala,
Sweden / 2. Author to whom correspondence should be addressed / Received July 9, 1992
Summary
Diurnal variations in leaf extension and turgor relaxation were measured in young willow leaves (Salix viminalis L.). Turgor relaxation was calculated from measurements of xylem water potential and osmotic potential of whole, detached
leaves that were incubated, without loss of water, under controlled conditions. There were clear diurnal variations in leaf
extension and in leaf turgor relaxation and the diurnal pattern of the difference in leaf turgor before and after relaxation
was in phase with that of leaf extension. The extent to which leaf turgor after relaxation may be related to threshold turgors
for growth and the possible importance of leaf turgor during leaf extension are discussed.
Keywords:
growth-effective turgor, turgor threshold for growth, willow.
