Xylem cavitation, leaf growth and leaf water potential in Eucalyptus globulus clones under well-watered and drought conditions

摘要

Leaf growth, predawn leaf water potential (Psi(pd)), evapotranspiration, stem maximum permeability, and its percentage loss of hydraulic conductivity ( PLC) were measured in rooted cuttings of selected clones of Eucalyptus globulus Labill. subjected to well-watered and drought conditions. Drought significantly reduced evapotranspiration, leaf growth and maximum permeability. E. globulus clones lost up to 70% of conductivity at values of Psi(pd) less negative than -1 MPa. PLC values higher than 85% could not be measured without causing leaf shedding. The coefficient related to the slope of the vulnerability curves ranged from 1.52-2.23. The lowest value was measured in the most drought-resistant clone, as estimated from field trials. Plants from this clone displayed higher drought-induced reductions in maximum permeability than plants from other clones, had significantly smaller leaves and maintained higher values of predawn leaf water potential as soil water content (SWC) declined.