© 1990 Heron Publishing—Victoria, Canada
Leaf growth of Eucalyptus globulus seedlings under water deficit
J. C. Metcalfe (1, 2), W. J. Davies (1) and J. S. Pereira (3)
1. Institute of Environmental and Biological Sciences, University of Lancaster, Lancaster LA1 4YQ, U.K. / 2. Author to whom correspondence should be addressed / 3. Department of Forestry, Instituto Superior de Agronomia, P-1399 Lisboa Codex, Portugal / Received May 12, 1989
Summary
Eucalyptus globulus Labill. seedlings grown under field conditions in Portugal were watered either daily (control) or every 6 days (drought-treated).
Relative to those of control plants, rates of leaf production and leaf biomass accumulation were reduced by almost half in
drought-treated plants. However, whereas
expansion of new leaves on control plants slowed toward the end of the 30 day experiment, expansion of leaves of the same
age on drought-treated plants accelerated as a change in weather conditions resulted in midday plant water potentials above
–3.0 MPa. In plants that were left unwatered until they wilted and were then watered daily, expansion of the fifth leaf pair
from the apex was slower than that of the same pair of leaves of plants watered daily throughout; but it continued for about
twice as long and resulted in the same final leaf area. Drought treatment also caused a substantial reduction in the rate
of leaf production, which, in part, accounted for the effect of drought on leaf biomass production. In a greenhouse study,
witholding water for 15 days had only a slight effect on the length or width of adaxial epidermal cells, and the effect was
quickly reversed on rewatering.
